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Consultancy

Final report: Environmental pressures impacting riverfly populations. Aquascience Consultancy: Nov. 2013 AQC22/Salmon & Trout Association.

1

Completed on the 21st November 2013

Dr. Nick Everall MIFM C Env ℡ (01246) 239344

� [email protected]

ENVIRONMENTAL PRESSURES IMPACTING

RIVERFLY POPULATIONS IN UK RIVERS

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Executive Summary

� Studies of aquatic ecological condition across 4 limestone and 3 chalk rivers of ‘good ecological quality’ highlighted variable ecological and riverfly population condition when quantitative species resolution monitoring of aquatic invertebrate communities was applied.

� In general, as sediment, organic and nutrient impact signatures decreased across all of the 7 studied rivers there was a strong association with increasing overall aquatic invertebrate abundance and species richness. In turn these improvements in the general ecological condition of the study watercourses were supported by a rise in both general riverfly and specific up-winged fly richness. Many of the aforementioned bioquality measures showed statistically significant increases amongst the various river case studies where sediment, organic and nutrient impact fingerprints were reduced. Conversely on rivers where these stresses increased above reference or un-polluted conditions then general riverfly and up-winged fly biodiversity declined. It was also important to note that iconic Biodiversity Action Plan riverfly species like the Southern Iron Blue (Baetis niger) and the Red Data Base Scarce Purple Dun (Paraleptophlebia werneri) were only found at a few survey sites throughout these study rivers where the organic, sediment and nutrient signatures corresponded to clean ‘reference’ watercourse conditions.

� In 3 out of the 7 river studies, flow had a variable, and in all probability,

diluting influence upon the sediment, organic and total reactive phosphorous impact signatures detected. Conversely, by inference it should therefore be noted that over abstraction would both compound the impacts of the key identified stresses associated with riverfly demise and although there was little evidence from these studies, flow was known to directly influence the invertebrate community composition by itself.

� From the initial river studies, Total Reactive Phosphorous Index values ≤80%

were considered to indicate macroinvertebrate communities with more TRP invertebrate indicator species than would be expected from a clean water ‘reference’ community. In the Upper River Itchen in 2013 this TRPI threshold

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associated with chemical TRP levels ≥ 0.04 mg TRP/l. However, these results were tentative based upon the relatively small independent chemical and EA GQA biological datasets from 2013 in the River Itchen. A large chemical and biological database analysis of TRP and TRPI from UK GQA sites was in progress but needed to be completed to get a better handle on this relationship.

� It should also be remembered that nutrient [TRP] level was not the only identified key stressor responsible for riverfly demise or improvement across the case study watercourses in this report. Such findings were in agreement with other workers who state that it is not unusual to encounter a range of stresses impacting UK watercourses and only by tackling all of them can the ecological integrity of river habitats be secured.

� Of the pollutant stresses associated with riverfly and up-winged fly loss, the following safety thresholds were identified from the study rivers containing reference sites with good fly diversity and numbers.

Stress Biometric threshold ~Mean chemical threshold in mg/l

Organic enrichment Saprobic index ≤1.8 BOD ≤3, <0.3 ammonia and ≥ 6 dissolved oxygen

*Nutrient enrichment (Total Reactive Phosphorous)

TRPI ≥80 Tentatively 0.04 in chalk

rivers but needs national

study results - in progress *Sedimentation PSI ≥60 (preferably ≥80) No direct equivalent Flow velocity LIFE ≥8 No direct equivalent

* N.B. Normally TRPI and PSI are reverse scales i.e. a low %score = high stress

� There was also growing evidence that river water temperature is changing in response to climate change and that aquatic organisms respond to changing thermal conditions in complex ways. Given the dependence of phenology on heat accumulation, the emergence of insects is particularly susceptible to changing temperature and can have adverse effects on freshwater insects populations Such additional thermal pressures only make it more important to identify and protect sensitive riverfly rich watercourses from other pressures, such as organic, nutrient, suspended sediment loads or hydrological changes.

� The highly resolved biological data in the case studies in this report was important in identifying fine scale shifts in ecosystem structure that served as benchmark evidence of both current subtle improvements or impacts and an ‘early warning’ system for the detection of further improvement or deterioration in ecological condition across UK rivers. The current case studies re-iterated the investigational need for the collection of quantitative species-level data wherever it is possible to provide a ‘complete’ picture when addressing management decisions about highly ecologically sensitive areas like the rivers in the case studies examined in this report.

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Contents Page no.

1. Background 5

2. Case studies 6

2.1 Limestone rivers 7

2.1.1 The River Dove in Staffordshire (2009-2013) 7

2.1.2 The River Manifold in Staffordshire (2009-2013) 10

2.1.3 The River Hamps in Staffordshire (2009-2013) 12

2.1.4 The River Wye in Derbyshire (2013) 15

2.2 Chalk rivers 17

2.2.1 The Bourne Rivulet in Hampshire (1989-2013) 18

2.2.2 The River Test in Hampshire (1995-2013) 23

2.2.3 The River Itchen in Hampshire (1995-2013) 27

2.2.4 Historic perspectives and wider pressures for riverfly populations 28

Acknowledgements

References

Appendices

Appendix 1 - Details of biometric testing used on the species macroinvertebrate community data across the various river case studies highlighted in this report.

Study Limitations

This report was prepared by Dr. Everall of Aquascience Consultancy at the request of Paul Knight of the Salmon & Trout Association. This report has been produced by Aquascience Consultancy within the terms of the contract with the client and taking account of the resources devoted to it by agreement with the client. We disclaim any responsibility to the client and others in respect of any matters outside of the specific scoping of this report. This report is confidential to the client, and we accept no responsibilities to third parties to whom this report, or any part thereof, is made known. Any such party relies on the contents of the report at their own risk. Any changes to any current UK and international ecotoxicological standards outlined in this report may cause the opinion, advice and conclusions set out in this report to become inappropriate or incorrect.

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1. Background

While there have been great strides in improving the ecological quality of many UK rivers over the last 50 years, relentless population expansion is putting more pressure upon finite aquatic resources through e.g. the direct abstraction of water for drinking water, the disposal of human waste and associated intensity of agricultural operations impinging upon our wetlands. Indeed, many of these issues are variably responsible for why, in the UK, fewer than 40% of surface waters were in good ecological status in 2009, at an early stage of the Water Framework Directive and river basin management plans with only 5% more expected to reach good ecological status by 2015. Under pinning robust ‘good ecological status’ are the aquatic macroinvertebrates which form a fundamental component of watercourse ecosystems such that increasing the invertebrate abundance and diversity strengthens the ecological integrity of watercourses (Spänhoff and Arle, 2007). Amongst these integral invertebrate components of the aquatic ecosystem are the riverfly groups of the Ephemeroptera mayflies (Ephemeroptera), stoneflies (Plecoptera) and caddis flies (Trichoptera). These species-rich orders represent a significant proportion of aquatic invertebrate biodiversity (Chadd and Extence, 2004 and Hering et al., 2009) and an important food-chain resource for other organisms; especially fish (Dineen et al., 2007). Amongst these riverfly groups, the most pollutant sensitive and economically important riverflies identified for many salmon, trout and grayling fly fishing rivers are the up-winged flies or mayflies (Wright et. al., 1996 & Bennett and Gilchrist, 2010). Any aquatic entomologist, angler or non-angler over the age of 50 will tell you that a trip down the local river 50 years ago involved having to clear the windscreen of all the collected riverflies. Many automobiles at that time were actually fitted with insect deflector’s designed to reduce this then commonplace problem. Such observations can easily be dismissed as hearsay evidence of the past quantum of riverfly populations but they are supported by more recent scientific facts of a decline in species rich riverfly groups across a number of UK watercourses in recent decades (Frake and Hayes, 2001, Bennett and Gilchrist, 2010 and Everall, 2013b). To understand potential riverfly loss and to provide facts for evidence based policies or practical in-stream management to deliver solutions then aquatic biological monitoring data bases are required that reverse the trend in UK Regulatory biomonitoring practices across our rivers in recent decades. Regulatory biomonitoring of watercourses in the UK over the last 30 years has progressively moved towards more broad brush semi-quantitative family level analysis of our aquatic invertebrate communities but this has insufficient taxonomic and abundance resolution to enable the assessment of either spatial or temporal trends in e.g. riverfly species biodiversity. Over the last decade it has been more widely accepted that aquatic faunal data often needs to be resolved to species level to adequately fulfil operational and legislative obligations for river management and conservation purposes (Arscott et al., 2006, Everall, 2010, Monk et. al., 2011 and Mainstone, 2012). Combined with the collection of more detailed aquatic invertebrate community data across a number of UK rivers there has been the recent advances in biometric

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fingerprinting which provide causal stress signatures responsible for any detected impacts or improvements in aquatic ecological quality. For example, municipal and agricultural impacts in receiving watercourses often manifest themselves through the impacts of organic pollution, nutrient enrichment and siltation (Hellawell, 1986, Extence et. al., 2010 and Everall, 2010). Siltation can now be biologically assessed using a sediment-sensitive macroinvertebrate metric, PSI (Proportion of Sediment-sensitive Invertebrates) at family or species level (Extence et. al., 2010) and this acts as a proxy to describe temporal and spatial impacts of sediment inputs to watercourses. Organic enrichment has been assessed using species level Saprobic indexing with macroinvertebrates for over 50 years in the rest of Europe (Pantle and Buck, 1955, Zelinka and Marvan, 1966 and Hellawell, 1986) but was not widely utilised in the UK because routine Regulatory biological monitoring moved progressively away from species level work in this country, until very recent years. Many studies have compared the results of different benthic macroinvertebrate metrics used to assess the impact of organic pollution (Hellawell, 1986, Calow & Petts, 1993 and Hauer & Lamberti, 1996). The Saprobic Index was found to work better than the Average Score Per Taxon or ASPT (Armitage et. al., 1983), utilised in the Regulatory UK RIVPACS based monitoring, as a measure of watercourse stress gradients in those European countries where macro-invertebrates were subject to a species as opposed to a lower family level of macroinvertebrate community profiling (Sandin and Hering, 2004). Phosphorous impacts upon the receiving ecology can now be assessed from aquatic invertebrate community composition using the Total Reactive Phosphorous or TRP Index (Everall, 2005, Everall, 2010, Everall and Farmer, 2012 and Everall, 2013b & c) which was developed in collaboration with Paisley et. al. (2003 and 2011) from phosphorous indicator work in UK watercourses using macroinvertebrates. Initial trials of the macroinvertebrate TRP Index have produced statistically comparable results with the Trophic Diatom Index (TDI) which, along with the higher plant (macrophyte) based Mean Trophic Rank, remained the key regulatory e.g. Water Framework Directive (WFD) biometrics used to assess nutrient enrichment in watercourses. The evidence for both riverfly population demise and the causative pressure sensitive stresses are provided in this report across a number of varied aquatic ecological investigations of UK rivers where the rarer quantitative species level aquatic faunal data was available and multi-biometric analyses had been undertaken. It is not, and because of the relative lack of species invertebrate community data, cannot be a definitive study at this point but it starts to provide the much needed resolution of study that highlights a number of causes of riverfly population gain and decline in some UK rivers in recent decades. Any field identified stresses exhibiting a mechanistic link with riverfly population impacts, as with all good ecological studies, will need to be followed up by controlled ecotoxicological laboratory testing to evaluate the quantum of potential cause and effect relationships.

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2. Case studies

Longer-term and even ‘snap-shot’ species datasets on UK rivers are relatively rare but they are what is required to attempt to tease out both where wider aquatic ecological condition and in the case of this study, up-winged fly populations may or may not be depauperate and what environmental stresses associate with such conditions. The majority of background and backbone Regulatory biomonitoring sites on our rivers in England and Wales are referred to by the Environment Agency as General Quality Assessment (GQA) sites for aquatic macroinvertebrate assessments or other biological and chemical sampling. To date the biological macroinvertebrate community data that has been collected has not been routinely taken to a species level of analysis for the purposes of e.g. WFD assessment and so it is fundamentally unsuitable to try and assess mayfly or few other species richness and abundance from such a dataset. It should be stressed that the Regulatory monitoring philosophy has changed in recent years with a move back to more species level data collection but alas this did not currently provide a large a spatial and temporal national GQA dataset to interrogate for this study. The relatively new Angler’s Riverfly Monitoring scheme is equally data limited in this respect because it was designed as a simple pollution sentinel on our rivers by analysing a bespoke group of mayfly, caddis and stoneflies to group or family level. These monitoring data synopses were not a criticism of historic routine biological quality or riverfly monitoring in the UK because these monitoring tools were fit for the purposes that they were designed for at that time. However, family level analysis of mayfly or any other riverfly populations would at best be crude and at worst, potentially misleading. The difference in the resolution of ecological condition assessment and the associated pressure-sensitive trait analysis between family and species level macroinvertebrate data can be large (Everall and Farmer, 2012). Furthermore, river SSSI (and SAC) networks are designated for their river habitat by including their characteristic biological communities (Mainstone and Hatton-Ellis, 2011). On this basis it appeared outwardly counter-intuitive to consider any general or pressure specific ecological indicators that operate at less than species level if the indicators are to be sufficiently sensitive to loss of fishery and conservation value resulting from anthropogenic impacts. The following are the findings from a number of species level macroinvertebrate case studies in SAC and non-SAC rivers throughout the UK in recent years. 2.1 Limestone rivers

2.1.1 The River Dove in Staffordshire (2009-2013)

All the sampling techniques, raw data and analytical methodologies employed in studying riverfly populations through the Upper River Dove catchment in 2009-2013 can be found in Everall (2010). A large spatial study of the Upper River Dove catchment in Derbyshire-Staffordshire was undertaken in 2009 by Natural England (Everall, 2010) as a benchmark of aquatic ecological and pollutant condition to both target Catchment Sensitive Farming investment and measure post-investment watercourse condition respectively. The graph overleaf is typical of the sort of detail on mayfly population status through the River Dove in 2009 that is available through the benchmark report (Everall, 2010).

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Mayfly profiles in River Dove in Autumn 2009

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Site 1

Site 3

Site 5

Site 7

Site 1

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Site 1

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Site 1

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ep

sam

ple

The Mayfly

Blue-winged Olive

Ditch Dun

Turkey Brown

Olive Upright

Brook Dun

Other flat bodied

Yellow May Dun

The mayfly (Ephemera danica) and the blue-winged olive (Serratella ignita) were dominant in only modest numbers through the River Dove in May 2009 and they were replaced in dominance by the olive upright (Rhithrogena semicolorata) in the upper reaches of the river with some nymphs shown below.

Ephemera danica Serratella ignita Rhithrogena semicolorata

There are also a number of Environment Agency reports documenting the details of the ongoing study and findings (Everall, 2013d) from which the following findings relating to the longer-term riverfly population status have been taken. The graph overleaf shows a synopsis of the general aquatic faunal condition (R and abundance) with the more specific riverfly (No. of EPT) and up-winged fly or mayfly (No. of UWF) plus associated patterns of pressure sensitive stresses in the watercourse e.g. siltation (PSI) and flow velocity (LIFE) fingerprints in the invertebrate communities.

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R (

specie

s r

ichness)

EP

T (

no. m

ay-c

addis

-sto

nefly)

UW

F (

no. m

ayflie

s)

S (

org

anic

pollu

tion)

LIF

E (

flow

)

*PS

I (s

ilt)

*TR

PI ([

P] enrichm

ent)

A (

faunal abundance x

103 m

-2)

2009

2011

2013

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Biometric quality and stress

gradient ↑

Measure

Year (Spring)

Aquatic ecological condition and key watercourse stresses in the River Dove near Hartington 2009-

2013

2009

2010

2011

2012

2013

*Please note that both Percentage Sedimentation (PSI) and Total Reactive Phosphorous indices have been inverted because low percentage values traditionally represent high sediment and total reactive phosphorous signatures in the ecology but this was considered counter-intuitive to the reader. High percentage values now represent high biometric stress gradients in the graphs throughout this report unless stated otherwise.

The key findings from this ~5 year study was that as flow velocity slightly increased, sediment and nutrient [P] levels dissipated between 2009-2013 in association with a marked increase in overall riverine invertebrate abundance and species richness which was under pinned by a rise in both general riverfly and specific up-winged fly richness. Many of the aforementioned biometrics showed statistically significant (P≤ 0.05) increases over the study period from 2009 to 2013 (Everall, 2013d) as shown in the graph below.

Ecological quality in upper River Dove at Beresford Dale from 2009 to 2013

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R. Dove Spring

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R. Dove Autumn

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R. Dove Autumn

2011

R. Dove Spring

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2012

R. Dove Spring

2013

BM

WP

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. m

-2 (9

5%

C.L

)

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Sp

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R)

m-2

(95%

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.)

BMWP

Faunal abundance no. m-2

R (species richness)

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The previous results for the River Dove are temporal patterns over a fixed spatial point but the same temporal associations were evident amongst the other sample sites in the River Dove long-term CSF study (Everall, 2013d). The new Total Reactive Phosphorous Index (TRPI) using macroinvertebrate community signatures and developed by Everall (2005) from indicator taxa highlighted in Paisley et. al. (2003 and 2011) will be mentioned throughout this report. In light of this it appeared prudent to highlight the results of an interpolation of Trophic Diatom Index (TDI) and TRPI results for all of the Upper River Dove sites studied in 2009-2010 in the graph below.

Trophic Diatom Index (TDI - diatoms) versus Total Reactive Phosphorous Index (TRPI -

macroinvertebrates) at sites through the Upper River Dove in 2009-2010

R2 = 0.4379

R2 = 0.3606

R2 = 0.406

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d/s junc

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ank

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1A

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u/s Har

tingt

on C

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ry

Und

er W

hittle

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r Brid

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n fo

otpa

th fr

om H

ollin

scloug

h

Site 2

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Brook

from

Ten

terh

ill

u/s Bra

ndside

and

oth

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rook

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Site 2

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Axe E

dge

Sample site for diatoms and macroinvertebrates

TD

I% a

nd

TR

PI% TDI

TRPI Spring

TRPI Autumn

Linear (TDI)

Linear (TRPI Spring )

Linear (TRPI Autumn)

Higher TDI values represent higher nutrient enrichment but lower TRPI values counter-intuitively represent higher [TRP] enrichment and unlike the other graphs in this report they have been left in their original formatting in the graph above. TDI and TRPI in this test therefore produced highly comparable nutrient signatures in terms of sensitivity and slope across the chosen study sites.

2.1.2 The River Manifold in Staffordshire (2009-2013)

All the sampling techniques, raw data and analytical methodologies employed in studying riverfly populations through the Upper River Dove catchment in 2009-2013 can be found in Everall (2010). The graph overleaf is typical of the sort of detail on mayfly population status through the River Manifold in 2009 that is available through the benchmark report (Everall, 2010).

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Mayfly profile in the River Manifold in Spring 2009

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Site 1

Site 2

Site 3

Site 4

A

Site 4

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A

Site 5

Site 6

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Site 1

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Nu

mb

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per

3 m

in k

ick-s

weep

sam

ple

Mayfly

Blue-winged Olive

Ditch Dun

Turkey Brown

Olive Upright

Large Brook Dun

Other flat bodied

Yellow May Dun

Flat bodied mayflies (Ecdyonurus and Rhithrogena semicolorata) were dominant in modest numbers through the River Manifold in May 2009 and were complimented in dominance by the blue-winged olive (Serratella ignita) towards the upper reaches of the river with some nymphs shown below.

Ecydonorus venosus/dispar/torrentis Rhithrogena semicolorata Serratella ignita There are also a number of Environment Agency reports documenting the details of the ongoing study and findings (Everall, 2013d) from which the following findings relating to the longer-term riverfly population status have been taken. The graph overleaf shows a synopsis of the general aquatic faunal condition (R and abundance) with the more specific riverfly (No. of EPT) and up-winged fly or mayfly (No. of UWF) plus associated patterns of pressure sensitive stresses in the watercourse e.g. siltation (PSI) and flow velocity (LIFE) fingerprints in the invertebrate communities.

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2009

20120

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B io met r ic qualit y and

st ress grad ient ↑

M easure

Y ear ( Sp ring)

Aquatic ecological condition and key watercourse stresses in the River Manifold

near Longnor 2009-2013

2009

2011

2012

2013


The key findings from this ~5 year study was that as flow velocity slightly increased, sediment and nutrient [P] levels dissipated between 2009-2013 along with a marked increase in overall riverine invertebrate abundance and species richness which was under pinned by a rise in both general riverfly and specific up-winged fly richness. Many of the aforementioned biometrics showed statistically significant (P≤ 0.05) increases over the study period from 2009 to 2013 (Everall, 2013d). The previous results for the River Manifold are temporal patterns over a fixed spatial point but the same temporal associations were evident amongst the other sample sites in the River Manifold long-term CSF study (Everall, 2013d). 2.1.3 The River Hamps in Staffordshire (2009-2013)

All the sampling techniques, raw data and analytical methodologies employed in studying riverfly populations through the Upper River Dove catchment in 2009-2013 can be found in Everall (2010). The graph overleaf is typical of the sort of detail on mayfly population status through the River Hamps in 2009 that is available through the report (Everall, 2010).

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Mayfly profiles in the River Hamps in Spring 2009

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200

250

Site 1 Site 2 Site 3 Site 4 Site

4A

Site

5A

Site 6 Site 7 Site 8 Site 9 Site

10

Site

11

11A 11B Site

11C

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Site

14

Nu

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per

3 m

in k

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weep

sam

ple

Mayfly

Blue-winged Olive

Ditch Dun

Turkey Brown

Olive Upright

Large Brook Dun

Other flat bodied

Yellow May Dun

The R. Hamps had comparable mayfly numbers to the River Manifold but dominated by the blue-winged olive (Seratella ignita) and the olive upright (Rhithrogena

semicolorata) plus a marked presence of the Ditch Dun (Haprophlebia fusca) at various main river sites in May (September) 2009.

There are also a number of Environment Agency reports documenting the details of the ongoing study and findings (Everall, 2013d) from which the following findings relating to riverfly population status have been taken. The graph overleaf shows a synopsis of the general aquatic faunal condition (R and abundance) with the more specific riverfly (No. of EPT) and up-winged fly or mayfly (No. of UWF) plus associated patterns of pressure sensitive stresses in the watercourse e.g. siltation (PSI) and flow velocity (LIFE) fingerprints in the invertebrate communities.

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R (

sp

ecie

s r

ich

ne

ss)

EP

T (

no

. m

ay-c

ad

dis

-sto

ne

fly)

UW

F (

no

. m

ayflie

s)

S (

org

an

ic p

ollu

tio

n)

LIF

E (

flo

w)

*PS

I (s

ilt)

*TR

PI

([P

] e

nrich

me

nt)

A (

fau

na

l a

bu

nd

an

ce

x 1

03

m-2

)

2009

20120

10

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90


gradient ↑

Measure

Year (Spring)

Aquatic ecological condition and key watercourse stresses in the River Hamps near

Onecote 2009-2013

2009

2011

2012

2013


Many of the overall increases in riverfly and specific mayfly species richness in response to reduced organic, nutrient and sediment loads across the River Dove, Manifold and Hamps between 2009 and 2013 also contained specific increase in the abundance of riverflies as shown in the example graph below for the River Hamps.

Relative abundance of mayfly nymphs in Mixon Hay Brook below farms between 2009 and 2013

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Spring 2009 Autumn 2009 Autumn 2011 Spring 2012 Autumn 2012 Spring 2013

Year/season

Nu

mb

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hs 3

min

-1 k

ick

/sw

eep

sam

ple

B. scambus

Ecdyonorus sp.

Rhithrogena sp.

Baetis scambus Ecdyonorus sp. Rhithrogena sp.

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The key findings from this ~5 year study was that, irrespective of flow regime, as sediment and nutrient [P] levels dissipated between 2009-2013 there was a marked increase in overall riverine invertebrate abundance and species richness which was under pinned by a rise in both general riverfly and specific up-winged fly richness. Many of the aforementioned biometrics showed statistically significant (P≤ 0.05) increases over the study period from 2009 to 2013 (Everall, 2013d). The previous results for the River Manifold are temporal patterns over a fixed spatial point but the same temporal associations were evident amongst the other sample sites in the River Hamps long-term CSF study (Everall, 2013d). It should also be noted that now rare and Biodiversity Action Plan (BAP) riverfly species like the Southern Iron Blue (Baetis niger) and iconic upland species like the Large Stonefly Dinocras

cephalotes were only found at the upper survey sites in this studies of the River Dove, River manifold and River Hamps where organic, sediment and nutrient signatures corresponded to clean reference watercourse conditions (Everall, 2010). 2.1.4 The River Wye in Derbyshire (2013)

All the sampling techniques, raw data and analytical methodologies employed in studying riverfly populations through the Upper River Wye catchment in 2013 can be found in Everall (2013b). The graph below was typical of the sort of detail on mayfly population status through the River Wye in 2013 that was available through the report (Everall, 2013b).

Ecdyonuru

s s

p.

Rhithro

gena s

p.

Ephem

era

danic

a

Para

lepto

phle

bia

subm

arg

inata

Serr

ate

lla ignita

Caenis

riv

ulo

rum

or

Caenis

luctu

em

Baetis s

cam

bus

Baetis r

hodani

Baetis m

uticus

Baetis fuscatu

s

BA

P B

aetis n

iger

Site 8 d/s Buxton - Spring 2013

Site 7 Below Topley Pike - Spring 2013

Site 6 d/s Blackwell cottages - Spring 2013

Site 5 u/s Monksdale - Spring 2013

Site 4 d/s Monksdale - Spring 2013

Site 3 d/s Tideswell Brook - Spring 2013

Site 2 d/s Litton Mill - Spring 2013

Site 1 d/s Cressbrook Mill - Spring 2013

d/s R. Lathkill - Spring 2013

Mayfly species

River Wye survey site

Biodiversity of up-winged flies through River Wye (through SSSI reaches 70 & 71) in Spring of 2013

The key findings from the 2013 study in the River Wye was that, irrespective of flow regime, as sediment and nutrient [P] levels dissipated down the river corridor there was a marked increase in overall riverine invertebrate abundance and species richness which was under pinned by a rise in both general riverfly and specific up-winged fly richness as shown in the graph overleaf.

Flow �

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Sediment (PSI) and phosphorous (TRPI) enrichment with up-winged fly species richness (UWF

Species) through the River Wye below Buxton in the Spring of 2013

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8 d/s Buxton 7 Below

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cottages

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Monksdale

4 d/s

Monksdale

3 d/s

Tideswell

Brook

2 d/s Litton

Mill

1 d/s

Cressbrook

Mill

d/s

confluence

with R.

Lathkill

To

tal R

eacti

ve P

ho

sp

ho

rou

s I

nd

ex (

TR

PI)

an

d P

erc

en

tag

e

Sed

imen

tati

on

In

dex (

PS

I) (

±95%

C.L

.)

0

2

4

6

8

10

12

No

. U

p-w

ing

ed

Fly

Sp

ecie

s

TRPI

PSI

UWFSpecies

The spatial pattern for an increasing signature of [P] moulding of the receiving invertebrate communities in the River Wye in 2013 was very similar to the pattern for mild organic enrichment (S for species Saprobic index) in the graph below.

Organic (S) and phosphorous (TRPI) enrichment with total aquatic fauanl species richness (R)

through the River Wye below Buxton in the Spring of 2013

0

10

20

30

40

50

60

70

80

90

100

8 d/s Buxton 7 Below

Topley Pike

6 d/s

Blackwell

cottages

5 u/s

Monksdale

4 d/s

Monksdale

3 d/s

Tideswell

Brook

2 d/s Litton

Mill

1 d/s

Cressbrook

Mill

d/s

confluence

with R.

Lathkill

To

tal R

eacti

ve P

ho

sp

ho

rou

s In

dex (

TR

PI)

an

d a

qu

ati

c f

au

nal

sp

ecie

s r

ich

ness (

R)

(±95%

C.L

.)

0

0.5

1

1.5

2

2.5

Sa

pro

bic

in

dex (

S)

(±95%

C.L

.)

TRPI

R

S

It is important to start to understand that while we are not talking about marked pollution impacts in most of these studies we are starting to unravel the impacts of relatively mild organic (ammonia, BOD ..), inorganic (reactive phosphorous ..) and sediment upon riverfly richness and abundance in UK rivers. Small increases or reductions in organic, nutrient and sediment load, under the marked pollution radar, associated respectively with both loss and gain of aquatic riverfly species richness and abundance in the River Dove, Manifold, Hamps and Wye studies from 2009-2013. The biometric, chemically measured and inferred BOD levels in the study reaches of the River Dove, Manifold and Hamps all showed a reduction in BOD from ~1-6 mg/l

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17

to 1-2 mg/l from 2009 to 2013 (Everall, 2013d). This data was very interesting because increased abundances of taxa sensitive to organic pollution were also correlated with reductions in mean BOD from around 1.6 mg/l to 1.3 mg/l in river studies by Durance and Ormerod (2009). Similarly, in an analysis of environmental change in the Wye catchment, Herefordshire, Clews and Ormerod (2009) found that observed improvements in the macroinvertebrate community over the period 1989-2000 were best explained by reductions in the level of organic pollution, from around 1.5mg/l mean BOD to around 0.7 mg/l. In a recent study of nearly 600 Danish streams over an 11-year period, Friberg and others (2010) also observed strong relationships between the abundance of certain pollution-sensitive invertebrate taxa and mild levels of organic enrichment, which were not explicable through inter-correlation with key habitat variables. The stonefly genus Leuctra showed the highest sensitivity, with occurrence declining sharply at BOD levels above 1.6 mgl-1. Further study of the 2009 species macroinvertebrate community data from the River Dove indicated that ~13 macroinvertebrate species were lost in moving up one ‘band of organic load’ under mild (nutrient enriched) to critical (mildly organically polluted) field conditions with the bands of organic load highlighted below from Everall and Farmer (2012).

Saprobic Index Degree of organic load Usual mean BOD in mg/l

2.7 - 3.2 Strongly polluted 7-13 2.3 - <2.7 Critical 5-10 1.8 - <2.3 Mild 2-6 1.5 - <1.8 Small 1-2

Such correlative analyses do not provide absolute proof of cause and effect, but the lack of clear relationships with other possible environmental influences from other workers and the findings of our current studies in the upper River Dove, Manifold, Hamps and Wye strongly suggested a mechanistic link between riverfly loss or gain with combined organic (BOD ..), nutrient ([TRP] and sediment levels in these watercourses. The next step would be to test the field observations and hypotheses about the lesser understood stresses of sediment and nutrient in the laboratory under controlled conditions e.g. the impacts of varied independent fine (inert) sediment, TRP and combined sediment/TRP upon up-winged fly egg survival. A costed research proposal was submitted by the author to the Environment Agency via the Angling Trust in 2012 but there has been no funding found to enable such studies to date. It should also be noted that the now rare and Biodiversity Action Plan (BAP) riverfly species of the Southern Iron Blue (Baetis niger) was only found at the survey sites in the River Wye where organic, sediment and nutrient signatures corresponded to clean reference watercourse conditions (Everall, 2013b). 2.2 Chalk rivers

It should be noted that there was less species and fully quantitative level data on macroinvertebrate communities of the chalk rivers than that for the limestone river’s at present but this is starting to be addressed by the Environment Agency and numerous independent riparian Stakeholders in recent years.

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18

2.2.1 The Bourne Rivulet in Hampshire (1989-2013)

All the sampling techniques, raw data and analytical methodologies employed in studying riverfly populations through the Bourne Rivulet catchment from 1989-2013 can be found in Everall (2013b). A large temporal and spatial desk top study of essentially family level data of the Bourne Rivulet was undertaken in 2013 by the Bright Waters Trust (Everall, 2013c) as a hind cast understanding of aquatic ecological and pollutant condition of the watercourse to date. In the Bourne Rivulet, family level biometric data indicated that mild organic pollution, nutrient and sediment had all spatially and temporally had a hand in moulding the ecological condition of the watercourse over the last ~25 years as shown in the graphs overleaf which examine just the organic and sediment signatures in the two upper rivulets.

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19

Bourne West Rivulet ‘reference’ site 1989-2013

Organic enrichment and siltation in Bourne West Rivulet 200m downstream SMB cress farm and

factory (EA data 1989-*2013) *EA/Aquascience Consultancy joint data

0

10

20

30

40

50

60

70

80

90

100

8.11

.89

17.1

.90

24.4

.90

10.7

.90

2.10

.90

7.1.

9129

.4.9

124

.7.9

1

23.1

0.91

15.1

.92

28.4

.92

6.7.

925.

10.9

226

.1.9

321

.4.9

36.

7.93

6.10

.93

6.4.

9429

.9.9

421

.4.9

520

.6.9

5

30.1

0.95

22.5

.96

13.7

.96

16.9

.96

30.1

0.97

13.5

.98

19.1

0.98

25.1

.99

10.4

.99

6.6.

9925

.6.0

316

.1.0

411

.5.0

4

20.1

0.04

16.9

.05

7.3.

0621

.4.0

6

16.1

1.06

29.4

.07

2.11

.07

28.5

.08

29.1

1.08

30.1

1.09

4.6.

13

Sample date

Sil

tati

on

(P

SI)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Org

an

ic e

nri

ch

me

nt

(Sa

pro

bic

in

de

x)

PSI

Saprobic index

The Bourne West Rivulet was long regarded by the Environment Agency and predecessor organisations (Soulsby, 1985) as a surrogate reference i.e. un-impacted site for this headwater reach of the Bourne Rivulet. However, in organic enrichment terms this was clearly not the case and subject as it has been to some degree of discharge-seepage from the St. Mary Bourne cress farm and upstream CSO’s this watercourse should not be organic enrichment benchmarked using West Rivulet Saprobic data. The Bourne West Rivulet had clearly long been subject to organic enrichment with a receiving watercourse fauna indicating a predominance of fauna tolerant of organic enrichment (betamesosaprobic) from 1989-2005. Post-2005, following EA instigated operational and discharge changes at St. Mary Bourne cress farm, there was a period of gradual recovery in the organic moulding of the aquatic fauna until 2006 when organic enrichment started to return to pre-2005 levels on what appeared to be a potentially worrying upward trend.

Un-silted

/naturally silted

Slightly silted

Moderately

silted

Silted

Heavily silted

Betamesosaprobic - moderate

organic enrichment

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20

Bourne East Rivulet site 1989-2013

Organic enrichment and siltation in Bourne East Rivulet 200m downstream SMB cress farm and

factory (EA data 1989-*2013) *EA/Aquascience Consultancy joint data

0

10

20

30

40

50

60

70

80

90

100

8.11

.89

17.1

.90

24.4

.90

10.7

.90

2.10

.90

7.1.

9129

.4.9

124

.7.9

1

23.1

0.91

15.1

.92

28.4

.92

6.7.

925.

10.9

226

.1.9

321

.4.9

36.

7.93

6.10

.93

6.4.

9429

.9.9

421

.4.9

520

.6.9

5

30.1

0.95

22.5

.96

13.7

.96

16.9

.96

13.5

.98

19.1

0.98

25.1

.99

10.4

.99

25.6

.03

16.1

.04

11.5

.04

20.1

0.04

16.9

.05

7.3.

0621

.4.0

6

16.1

1.06

29.4

.07

25.5

.07

2.11

.07

28.5

.08

29.1

1.08

30.1

1.09

5.5.

1223

.5.1

24.

6.13

Sample date

Silta

tio

n (

PS

I)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Org

an

ic e

nri

ch

men

t (S

ap

rob

ic i

nd

ex)

PSI

Saprobic index

The Bourne East Rivulet had clearly long been subject to more marked organic enrichment than the West Rivulet, with a receiving watercourse fauna indicating a predominance of fauna highly tolerant of organic enrichment (alpha-betamesosaprobic) from 1989-2005. Post-2005, at the time of EA instigated operational and discharge changes at St. Mary Bourne cress farm, there was a period of gradual recovery in the organic moulding of the aquatic fauna until 2012 when organic enrichment started to return to pre-2005 levels with what appeared to be a sudden upturn between 2012 and 2013.

Un-silted

/naturally silted

Slightly silted

Moderately

silted

Silted

Highly silted

Betamesosaprobic -

moderate organic

enrichment

↑ Alpha-

betamesosaprobic -

marked organic

enrichment

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Dr. Nick Everall MIFM C Env �� [email protected] ℡℡℡℡ 01246 239344 21

The Bourne Report (Everall, 2013c) holds a great deal more detail of all of the environmental stresses associated with changes in ecological condition of the chalk river between 1989 and 2013 but much of this is on historic Environment Agency data at a family invertebrate community level. More recent species level studies have started to provide some insight into factors affecting riverfly populations in the Bourne Rivulet. Recent species level evidence suggested that organic enrichment (~Saprobic index) from a source between Stoke and Derrydown Farm, with further organic augmentation via the Bourne East Rivulet, associated with a pervasive fingerprint of reduced aquatic faunal abundance, overall species and more specific mayfly-stonefly-caddis (EPT) richness through the Bourne Rivulet as shown in part in the previous graphs and the figure below.

Organic enrichment (Saprobicity) and aquatic ecological condition through the Bourne Rivulet -

Spring 2013

0

5

10

15

20

25

30

35

40

Bourne Rivulet

Upstream over-

pumping at

Stoke

Bourne Rivulet

Upstream

Vitacress @

Derrydown

Farm

Bourne Rivulet

(West) 200m

d/s SMB Cress

Farm

Bourne Rivulet

(East) 200m d/s

SMB Cress

Farm

Site 5Bourne

Rivulet The

Island 1100m

d/s SMB Cress

Farm

Bourne Rivulet

Ironbridge

1800m d/s SMB

Cress Farm

Sample Site Flow

Aq

uati

c f

au

nal ab

un

dan

ce x

10

2 a

nd

no

. o

f

sp

ecie

s (

bio

div

ers

ity)

0

2

4

6

8

10

12

14

16

18

20

EP

T(S

) an

d S

ap

rob

ic in

dex

Abundance 3 min-1 kick-sweep


EPT(S)

Saprobic index

Similarly, the spatial pattern for sediment impacts in 2013 identified sediment (~PSI) incursion from a source between Stoke and Derrydown Farm, with further marked sediment augmentation via the Bourne East Rivulet, associated with a signature of reduced aquatic faunal abundance, overall species and more specific mayfly-stonefly-caddis (EPT) richness through the Bourne Rivulet as shown in the previous graphs and the figure overleaf.

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Siltation (PSI) and aquatic ecological condition through the Bourne Rivulet - Spring 2013

0

5

10

15

20

25

30

35

40

Bourne Rivulet

Upstream over-

pumping at

Stoke

Bourne Rivulet

Upstream

Vitacress @

Derrydown

Farm

Bourne Rivulet

(West) 200m

d/s SMB Cress

Farm

Bourne Rivulet

(East) 200m d/s

SMB Cress

Farm

Site 5Bourne

Rivulet The

Island 1100m

d/s SMB Cress

Farm

Bourne Rivulet

Ironbridge

1800m d/s SMB

Cress Farm

Sample Site Flow

Aq

uati

c f

au

nal ab

un

dan

ce x

102 a

nd

no

. o

f sp

ecie

s

(bio

div

ers

ity)

0

10

20

30

40

50

60

70

80

90

100

EP

T(S

) an

d P

SI

Abundance 3 min-1 kick-sweep


EPT(S)

PSI(S)

The graph below shows a synopsis of the general aquatic faunal condition (R and abundance) with the more specific riverfly (No. of EPT) and up-winged fly or mayfly (No. of UWF) plus associated patterns of pressure sensitive stresses in the watercourse e.g. siltation (PSI) and flow velocity (LIFE) fingerprints in the invertebrate communities of the upper West Rivulet in 2005 and 2013.

R (

specie

s r

ichness)

EP

T (

no. m

ay-c

addis

-sto

nefly)

UW

F (

no. m

ayflie

s)

*PS

I (s

ilt)

S (

org

anic

pollu

tion)

LIF

E (

flow

)

*TR

PI ([

P] enrichm

ent)

A (

faunal ab

undance

x 1

03 m

-2)

2005

2013

0

5

10

15

20

25

30

35

40

45

50


gradient ↑

Measure

Year (Spring)

Aquatic ecological condition and key watercourse stresses in the Bourne (West) Rivulet near St.

Mary Bourne 2005 and 2013

2005

2013


The graph overleaf shows a synopsis of the general aquatic faunal condition (R and abundance) with the more specific riverfly (No. of EPT) and up-winged fly or mayfly (No. of UWF) plus associated patterns of pressure sensitive stresses in the

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watercourse e.g. siltation (PSI) and flow velocity (LIFE) fingerprints in the invertebrate communities of the upper East Rivulet in 2005 and 2013.

R (

specie

s r

ichness)

EP

T (

no. m

ay-c

addis

-sto

nefly)

UW

F (

no. m

ayflie

s)

*PS

I (s

ilt)

S (

org

anic

pollu

tion)

LIF

E (

flow

)

*TR

PI ([

P] enrichm

ent)

A (

faunal ab

undance

x 1

03 m

-2)

2005

2013

0

10

20

30

40

50

60

70


gradient ↑

Measure

Year (Spring)

Aquatic ecological condition and key watercourse stresses in the Bourne (East) Rivulet near St.

Mary Bourne 2005 and 2013

2005

2013

*Please note that both Percentage Sedimentation (PSI) and Total Reactive Phosphorous indices have been inverted because low percentage values traditionally represent high sediment and total reactive phosphorous signatures in the ecology but this was considered counter-intuitive to the reader.

The key findings from these studies in the Bourne Rivulet were that, independent to flow velocity, as organic, sediment and nutrient [P] levels dissipated spatially in 2013 and temporally between 2005 and 2013 there was a marked increase in overall riverine invertebrate abundance and species richness which was under pinned by a rise in both general riverfly and specific up-winged fly richness. It should also be noted that now rare and Biodiversity Action Plan (BAP) riverfly species like the Southern Iron Blue (Baetis niger) and the Red Data Base (RDB) Scarce Purple Dun (Paraleptophlebia werneri) were only found at the upper survey sites in this study of the Bourne Rivulet where organic, sediment and nutrient signatures corresponded to clean reference watercourse conditions. 2.2.2 The River Test in Hampshire (1995-2013)

As yet there has been no hind cast analysis of historic family macroinvertebrate datasets on the River Test with the recently developed full suite of biometric tests for sediment, flow, nutrient and organic signatures of aquatic ecological condition but work is in progress to address this matter pending funding. Prior to 2013, the only comprehensive fully quantitative and species level analyses pertinent to riverfly population status in the River Test was undertaken by Dr. Cyril Bennett at Leckford upon Blue Winged Olive (Serratella ignita) populations (Bennett and Gilchrist, 2010) and the data is shown overleaf.

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The decline in the Blue Winged Olive (Seratella ignita) on the River Test at Leckford which has been reproduced with kind permission by the author from Bennett and Gilchrist (2010).

Blue Winged Olive (Serratella ignita) abundances at Leckford in River Test

The nymph data from Bennett and Gilchrist (2010) suggested a decline in the population size of the Blue Winged Olive mayfly at Leckford in the River Test post-1995 but monitoring ceased in 2004 and there was sadly no more data to assess the longer-term trend at this study site. However, the author is aware that there has been some recent species level and quantitative invertebrate community surveying undertaken in the River Test at Leckford in 2013 but due process relating to a Ph D submission and associated publications must be respected before this information can be made available in the public domain. Thanks to the forward thinking of several independent riparian owners a spatial spread of appropriate species community and fully quantitative sampling commenced through parts of the River Test in 2013. Initial studies in 2013 showed that fully quantitative replicate Surber net sampling produced bio-quality (BMWP, ASPT, NTAXA, R, EPT …) and biometric (PSI, S, LIFE, TRPI …) site results for the River Test that were not significantly different from semi-quantitative 3 minute kick-sweep net sample findings. To provide robust quantification of results in numbers of invertebrates m-2 the quantitative species invertebrate community data has been used in the graph overleaf from the same season and day of sampling in 2013 (Everall, 2013f).

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R (

sp

ecie

s r

ich

ne

ss)

UW

F (

no

. m

ayflie

s)

LIF

E (

flo

w)

*TR

PI ([

P]

en

rich

me

nt)

1st d/sLongparish

Ist main carrier u/s Stockbridge

d/s Stockbridge

0

10

20

30

40

50

60


gradient ↑

Measure

Site & Flow ↑

Aquatic ecological condition and key watercourse stresses in the River Test in Hampshire

from Long Parish → Stockbridge in Autumn 2013

1st d/sLongparish

2nd d/s Longparish

Ist main carrier u/s Stockbridge

2nd main carrier u/s Stockbridge

d/s Stockbridge


As siltation (PSI), organic (S) and nutrient TRP (TRPI) enrichment increased with decreasing flow velocity from Longparish down to below Stockbridge in the River Test in the Autumn of 2013 there was an associated loss of general riverfly → up-winged fly species richness and faunal abundance. The details of these individual stress impacts are highlighted in the graphs below and overleaf.

Species richness of riverflies and up-winged flies with mild organic enrichment through the River

Test from Long Parish to Stockbridge → Autumn 2013

0

5

10

15

20

25

30

1st d/sLongparish 2nd d/s Longparish Ist main carrier u/s

Stockbridge

2nd main carrier u/s

Stockbridge

d/s Stockbridge

Site and Flow →

No

. ri

verf

ly s

pecie

s m

-2 (±

95%

C.L

.)

0

0.5

1

1.5

2

2.5

Sap

rob

ic in

dex (

org

an

ic e

nri

ch

men

t)

EPT (no. may-caddis-stonefly)

UWF (no. mayflies)

S (organic pollution)

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There was a generally statistically significant (P<0.05) reduction in riverfly and up-winged fly species richness from Longparish → Stockbridge which appeared to inversely mirror the trend in rising organic enrichment through these reaches of the river.

Species richness of riverflies and up-winged flies with flow velocity through the River Test from

Long Parish to Stockbridge → Autumn 2013

0

5

10

15

20

25

30


Stockbridge


Stockbridge

d/s Stockbridge

Site and Flow →

No

. ri

verf

ly s

pec

ies m

-2 (

± 9

5%

C.L

.)

6.8

7

7.2

7.4

7.6

7.8

8

8.2

8.4

8.6

LIF

E (

Flo

w v

elo

cit

y)


UWF (no. mayflies)

LIFE (flow)

There was a generally statistically significant (P<0.05) reduction in riverfly and up-winged fly species richness from Longparish → Stockbridge which appeared to inversely mirror the trend in decreasing flow velocities through these reaches of the river.

Species richness of riverflies and up-winged flies with siltation through the River Test from Long

Parish to Stockbridge → Autumn 2013

0

5

10

15

20

25

30


Stockbridge


Stockbridge

d/s Stockbridge

Site and Flow →

No

. ri

verf

ly s

pecie

s m

-2 (±

95%

C.L

.)

0

10

20

30

40

50

60

70

80

90

100

Silta

tio

n (

PS

I)


UWF (no. mayflies)

*PSI (silt)

There was a generally statistically significant (P<0.05) reduction in riverfly and up-winged fly species richness from Longparish → Stockbridge which appeared to

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inversely mirror the trend in increasing sedimentation through these reaches of the river.

Species richness of riverflies and up-winged flies with nutrient (TRP) enrichment through the River

Test from Long Parish to Stockbridge → Autumn 2013

0

5

10

15

20

25

30


Stockbridge


Stockbridge

d/s Stockbridge

Site and Flow →

No

. ri

verf

ly s

pecie

s m

-2 (±

95%

C.L

.)

0

10

20

30

40

50

60

70

80

90

100

TR

P e

nri

ch

men

t (T

RP

I)


UWF (no. mayflies)

*TRPI ([P] enrichment)

There was a generally statistically significant (P<0.05) reduction in riverfly and up-winged fly species richness from Longparish → Stockbridge which appeared to inversely mirror the trend in increasing nutrient (TRP) enrichment through these reaches of the river. The key findings were that, unlike some of the finding from other watercourse case studies in this report the evident stress signatures of organic, sediment and nutrient impacts upon the ecology in the River Test in 2013 were potentially exacerbated by decreasing flow velocity with distance downstream which would, in all probability, associate with decreased flow (volume) dilution of point-source discharges and more diffuse pollution through this river corridor. It should also be noted that now rare and Biodiversity Action Plan (BAP) riverfly species like the Southern Iron Blue (Baetis

niger) and the Red Data Base (RDB) Scarce Purple Dun (Paraleptophlebia werneri) were only found at the upper survey sites in this study of the River Test where organic, sediment and nutrient signatures corresponded to clean reference watercourse conditions. 2.2.3 The River Itchen in Hampshire (1995-2013)

As yet there has been no hind cast analysis of historic family macroinvertebrate datasets on the River Test with the recently developed full suite of biometric tests for sediment, flow, nutrient and organic signatures of aquatic ecological condition but work is in planned with respect to this matter in 2014. At present, in the absence of any funding for hind cast family invertebrate analysis and collation of fully quantitative species level community invertebrate data we have taken a look at some of the environmental biometric stresses evident from EA GQA data in the area of the Upper River Itchen around Alresford. The biological ‘snap shot’ of pollutant stresses in the Upper River Itchen around Alresford in 2010-2013 was undertaken to compliment some current 2013 chemical nutrient investigations of

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phosphorous levels being undertaken by The Salmon & Trout Association in collaboration with Dr. P. Shaw at Southampton University. The graph below showed that in this reach of the Upper River Itchen the aquatic faunal signatures of nutrient (TRPI) impact declined downstream from Alreford to Itchen Stoke as the ‘summer’ (July-August 2013) chemical total reactive phosphorous levels dropped in the river and this was set against a backdrop of a moderate but declining sediment moulding of the watercourse ecology through this reach of the watercourse.

Siltation (PSI) and nutrient (TRP & TRPI) signatures in Upper → River Itchen from Alresford Itchen

Stoke 2010-2013

0

10

20

30

40

50

60

70

80

90

100

Alresfor

d

21.3

.13

Arle

1.7.

11

21.3

.13

8.4.

10

28.9

.10

24.3

.11

22.9

.11

26.3

.12

10.1

0.12

21.3

.13

d/s Can

dove

r Bro

ok

20.4

.10

28.9

.10

18.1

1.10

24.3

.11

22.9

.11

20.1

0.11

26.3

.12

21.3

.13

Itche

n Sto

ke

8.4.

10

28.9

.10

26.3

.12

14.9

.12

3.5.

13

Site, sample date and flow →

PS

I (s

ilta

tio

n)

an

d T

RP

I (T

RP

) %

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

Mean

To

tal R

eacti

ve P

ho

sp

ho

rou

s (

TR

P)

in m

g/l

Ju

ly-S

ep

tem

ber

2013 (

95%

C.L

.)

TRPI

PSI

[TRP]


Of interest to the River Itchen and the wider debate about [P] chemical standards for watercourses was the fact that as for PSI, TRPI values ≥ 20% are considered to indicate invertebrate macroinvertebrate communities with more TRP indicator species than would be expected from a clean water ‘reference’ community. In the Upper River Itchen this associated with chemical TRP levels ≥ 0.04 mg TRP/l. At present, without the accompanying resolution of species level macroinvertebrate community analysis it was not possible at present to determine what specific impacts this sediment and phosphorous moulding of the fauna was having on e.g. the receiving riverfly aspects of ecological condition in the River Itchen. 2.2.4 Historic perspectives and wider pressures for riverfly populations

There is an inherent contextual problem for all 21st Century biologists or water catchment managers trying to manage the ecological state of our rivers and that is that ‘reference’ sites are becoming increasingly rare because human modification of river systems is so pervasive that sites with a representative suite of minimally disturbed watercourse conditions have become increasingly scarce (Everall and Farmer, 2012). This is highlighted by e.g. the current state of siltation across rivers in England and

Tentative threshold

TRPI for ecological

moulding above

reference condition

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Wales as highlighted in the 2012 map below where the yellow, red and black dots represent moderate, poor and bad levels of watercourse sedimentation using the Percentage Siltation Index (Extence et. al., 2010 and Extence et. al., 2011).

Graph reproduced with the kind permission of Ian Humpheryes at the Environment Agency

The author and colleagues at Staffordshire University are currently working on a matching map for the biological signature of total reactive phosphorous (TRP) across UK watercourses using the new macroinvertebrate based TRP model but this is a voluntary exercise and effort limited at present by the lack of any funding. While we still may soon be able to produce a fairly comprehensive ‘current state of play’ for environmental stresses that may prove to be associated with riverfly demise, where that occurs, the detailed historic (pre-1970’s) macroinvertebrate community data required to make longer-term comparisons remains fairly elusive and compounded by later changes in the level of taxonomic analysis used on biological samples. Also, many of the watercourses where there is now evidence or riverfly and up-winged fly demise were not historically extensively biologically surveyed because many were regarded as clean, if not pristine and were not deemed to warrant investigational resources. However, if it exists, then any such distant historic biological data would be contextually very informative when analysed and referenced against environmental stress patterns like that shown e.g. for chemical nitrogen and phosphorous nutrient enrichment in the lower River Avon overleaf.

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Reproduced by the kind permission of Chris Mainstone at Natural England from Mainstone

(2010)

In conclusion, it should be remembered that this investigation was driven from evidence based case studies and long-term field observations of suspected riverfly demise. What was interesting was that a number of once regarded or measured ‘pristine’ UK rivers of current ‘good ecological status’ were showing evidence of riverfly demise in recent decades in association with relatively mild increases in sediment, nutrient, organic and occasionally reduced flow regimes. Conversely, a number of northern limestone rivers historically listed as of ‘good ecological status’ that received species level biomonitoring targeting of CSF investment went on to show significant improvement in riverfly population status and were clearly not at the optimum that previous river classification had implied. A number of historically degraded UK rivers have also shown massive improvements in ecological quality e.g. the River Trent and the River Erewash following multi-million pound investments in tackling pollutant inputs as shown for the River Trent overleaf.

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So the reader should not go away with the impression that all rivers in the UK are experiencing ecological and riverfly demise because it is a mixed bag of results. However, fewer than 40% of surface waters were in broad brush ‘good ecological status’ in 2009, at an early stage of the Water Framework Directive and river basin management plans with only 5% more expected to reach good ecological status by 2015. This report highlights that a number of ‘good ecological status’ were not or are not as good as they could be and hide more subtle ecological impacts because of the current resolution of analysis employed for Regulatory monitoring. Furthermore, there was a common thread of marked and often combined sediment, nutrient and organic signatures in the aquatic ecology of rivers experiencing loss of riverfly species richness and abundance but these factors were not the only stresses responsible for all cases of riverfly demise. It is not unusual to encounter a range of stresses impacting UK watercourses and only by tackling all of them can the ecological integrity of river habitats be secured (Mainstone and Clarke 2008). Although not burning in these studies, the wider picture needs to consider that over abstraction will both compound the impacts of the key identified stresses associated with riverfly demise and flow or lack of flow will influence the invertebrate community composition in itself. Similarly, other pollutants can occasionally dramatically decimate riverfly populations like the pesticide chlorpyrifos incursions into the South Wey in 2002-2003 (Everall, 2003) and the River Kennett in 2013 (Everall, 2013g) but these are usually readily differentiated from other stresses. There is also growing evidence that river water temperature is changing in response to climate change (Kaushal et al., 2010; van Vliet et al., 2011; Lough & Hobday et al., 2011; Isaak et al., 2012). Aquatic organisms respond to changing thermal conditions in complex ways (Ward & Stanford, 1982). Given the dependence of phenology on heat accumulation, emergence of insects is particularly susceptible to changing temperature and can have adverse effects on freshwater insects populations (Harper & Peckarsky, 2006; Durance and Ormerod, 2007; Thackeray et al., 2010 and Everall, 2013h). Such additional thermal pressures on the immediate horizon only make it more important to currently identify and protect sensitive riverfly rich watercourses

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from other pressures, such as agricultural pollution, suspended sediment loads or hydrological changes. So, while it is important to add to any growing evidence base of a documented quantum loss in some riverfly populations on any impacted rivers, there is a greater need to understand the root causes of these declines and thus to provide some solutions. The species level invertebrate community studies highlighted in this report have started to provide the necessary evidence on riverfly populations for impacted and un-impacted watercourses in the UK but there is much more work required to get a wider local and regional perspective upon this matter. The more riparian owners prepared to fund benchmarking their own waters using these techniques and the recent Environment Agency move towards collecting more species resolution biometric data will enable stress pinch points of riverfly demise to be more readily pin pointed and for targeted remedial measures to be applied in watercourses.

Acknowledgements

The author would like to thank Dr. Chris Mainstone at Natural England for helping to progress species level condition assessment on UK rivers. Similar thanks are also due to Dr. Chris Extence, Richard Chadd, Juliette Hall, Phil Smith, Dave Ottewell and Shirley Medgett at the Environment Agency for forward thinking in both development of biometric fingerprinting and application to field studies. Thanks to my colleagues Dr’s. Martin Paisley, Bill Walley and Dave Trigg at Staffs University in the development of the macroinvertebrate TRPI model to date.

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Details of biometric testing used on the species macroinvertebrate community data across the various river case studies highlighted in this report.

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Appendix 1 - Details of biometric testing used on the species macroinvertebrate

community data across the various river case studies highlighted in this report.

A number of pressure-sensitive biometrics are now available to determine fingerprints for siltation (Proportion of Sediment Sensitive Invertebrates or PSI), flow velocity conditions (Lotic Invertebrate Flow Evaluation or LIFE), organic enrichment (Saprobic index) and phosphate enrichment (Total Reactive Phosphorous Index or TRPI) from family and species level sample macroinvertebrate community data. These pressure-sensitive biometric tests were applied to both, where available, the historic EA GQA and the current 2013 macroinvertebrate sample data for all of the survey sites in the Bourne Rivulet catchment. Siltation from Proportion of Sediment-sensitive Invertebrates or PSI Physical assessment methods have traditionally been used to quantify riverine sedimentation, but Extence et. al. (2010) have proposed an alternative approach, the use of a sediment-sensitive macro-invertebrate metric, PSI (Proportion of Sediment-sensitive Invertebrates) which can act as a proxy to describe temporal and spatial impacts. Such techniques have also been used successfully at a large catchment scale to assess the spatial and temporal patterns of siltation in a watershed (Extence et. al., 2010, Everall, 2010 and Extence et. al., 2011). The PSI score describes the percentage of sediment-sensitive taxa (Table 1 overleaf) present in a sample and the metric is calculated using the matrix shown in Table 2 overleaf and then applying the following formula:

ε Sediment Scores for Sensitivity Groups A & B PSI (Ψ) = X 100

ε Sediment Scores for all Sensitivity Groups A, B, C & D

Table 1 Group Silt Tolerance Definition

A Taxa highly sensitive to sedimentation B Taxa moderately sensitive to sedimentation C Taxa moderately insensitive to sedimentation D Taxa highly insensitive to sedimentation E Taxa indifferent to sedimentation or excluded from the method for other

reasons.

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Table 2 Group Sediment Sensitivity Log Abundance. Rating (SSR) 1-9 10-99 100-999 1000+ A Highly Sensitive 2 3 4 5

B Moderately Sensitive 1 2 3 4 C Moderately

Insensitive 1 2 3 4

D Highly Insensitive 2 3 4 5 E Excluded - - - -

From the literature review in Extence et. al. (2010), appropriate abundance and affinity weightings have been incorporated into Table 2 to give the final PSI metric better definition. PSI scores range from 0 (entirely silted river bed) to 100 (entirely silt-free river bed). Extence et. al. (2010) suggested that when applied to species and family data respectively, the terms PSI (S) and PSI (F) are used. A provisional interpretation scheme for the data is shown in Table 3 below (Extence et. al., 2010). Table 3 PSI River Bed Condition

81 -100 Naturally sedimented/Unsedimented 61 - 80 Slightly sedimented 41 - 60 Moderately sedimented 21 - 40 Sedimented 0 - 20 Heavily sedimented

In the current study of the Bourne Rivulet catchment the macroinvertebrate results for siltation expressed as PSI are in fact PSI(S) as there was sufficient resolution at species level across the biological data sets (Appendix 2) to facilitate PSI(S) analysis. For EA GQA dataset evaluations this was not the case and here the macroinvertebrate results for siltation expressed as PSI are in fact PSI(F). Flow velocity conditions from Lotic Invertebrate Flow Evaluation or LIFE Many freshwater invertebrates have precise requirements for particular current velocities or flow ranges (Chutter, 1969; Hynes, 1970; Statzner et al., 1988; Brooks, 1990), and certain taxa are ideal indicators of prevailing flow conditions. As well as qualitative responses to flow changes, site specific studies also show that most taxa associated with slow flow tend to increase in abundance as flows decline, whereas most species associated with faster flows exhibit the opposite response (Moth Iversen et al., 1978; Extence, 1981; Cowx et al., 1984; Wright and Berrie, 1987; Boulton and Lake, 1992 and Wright, 1992). Alterations in community structure may occur as a direct consequence of varying flow patterns, or indirectly through associated habitat change (Petts and Maddock, 1994 and Petts and Bickerton, 1997).

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The Lotic-invertebrate Index for Flow Evaluation (LIFE) technique is based on data derived from established 3 minute kick-sweep net sampling of macroinvertebrates in order to assess the impact of variable flows on benthic populations (Extence et. al., 1999). The method links qualitative and semi-quantitative change in riverine benthic macroinvertebrate communities to prevailing flow regimes. The higher the LIFE score in comparable flow-habitat sections of watercourse the higher the prevailing flow conditions and vice versa. A close correlation anticipated by Extence et al., (2011) ‘in many instances’ was between LIFE and PSI. Extence et al., (2011) devised PSI and Extence et al., (1999) devised LIFE, but the relationship in the field has not been tested until recently. There was a clear correlation (r=0.91, p<0.01) between PSI and Life in the Everall (2010) study as recently highlighted in Farmer (2010). It may seem logical that affinity for high flows and low siltation are related, but this was not the complete picture in all preliminary studies to date. Extence et. al. (1999) suggested that when applied to species and family data respectively, the terms LIFE (S) and LIFE (F) are used. Organic pollution and enrichment from Saprobic index Many studies have compared the results of different benthic macroinvertebrate metrics used to assess the impact of organic pollution (Hellawell, 1987, Calow & Petts, 1993, Hauer & Lamberti, 1996 and Eurolimpacs, 2004,). The Average Score Per Taxon (ASPT) used by the Environment Agency with the computer model RIVPACS in the UK has been well correlated with the stress gradient in most stream types but the Saprobic Index worked better than ASPT in those countries (e.g. Germany, Austria and the Czech Republic) where macroinvertebrates were generally identified to a lower (species) as opposed to a higher (genus or family) level of identification (Leonard and Daniel, 2004). Saprobic indexing at the species and family level allowed a greater insight into the nature and quantum of organic pollution in watercourses than other methods since it accounted for species differences in tolerance to organic pollutants (e.g. elevated ammonia and lowering dissolved oxygen regimes) as opposed to generic estimates of whole family responses. The link between biological water quality and the saprobic system of watercourse classification was because benthic invertebrates are important within the stream community as a fundamental link in the food web between organic matter resources and ecosystem fishery health. A standardised method to assess the biological water quality in European watercourses is the saprobic classification system (saprobity = amount of degradable organic material). This classification system is based upon selected index organisms (indicators), whose appearance is related to the impact of degradable organic material. The saprobic value (s) is a number from 1,0 to 4,0. The category groups of the saprobic values are shown in Table 5 overleaf:

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Classification s

oligosaprobic 1,0 - <1,5

oligosaprobic – ß-mesosaprobic 1,5 - <1,8 ß-mesosaprobic 1,8 - <2,3

ß-mesosaprobic – α-mesosaprobic 2,3 - <2,7 α-mesosaprobic 2,7 - <3,2

α-mesosaprobic – polysaprobic 3,2 - <3,5 polysaprobic 3,5 – 4,0

In the calculation of the saprobic classification there are two values that are dedicated to each species: 1. the saprobic value (s) and 2. the indicator value (G) The saprobic value shows the appearance of the species in a specific range of water quality. Some species have a narrow tolerance range, this means that they are good indicators. The specific tolerance of the species is expressed by the indication value. The third term to calculate the saprobic classification is: 3. the frequency (A) of a particular species. Formula for the saprobic index:: S = ∑A*s*G ∑A*G S = saprobic index A = frequency s = saprobic value G = indicator value The latest Saprobic values (s) and indicator values (G) used throughout Europe were obtained by formal permission in writing from and Dr. Everall was granted (password) access to the EUROLIMPACS database (via www.freshwaterecology.info). Interpretation of Saprobic indices for levels of organic pollution and inferred chemical status was provided by Laenderarbeitsgemeinschaft Wasser (LAWA), Mainz, Germany, 1976 shown in Table 6 overleaf:

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Quality class Degree

of

organic

load

Saprobic state Saprobic

index

Usual

BOD5

in mg/L

Usual

NH4-

N in

mg/L

Usual

O2-

minima

in mg/L

I no or

minimal oligosaprobic 1,0-<1,5 1 <0,1 8

I-II small oligo-betamesosaprobic 1,5-<1,8 1-2 ~0,1 8

II mild betamesosaprob 1,8-<2,3 2-6 <0,3 6

II-III critical beta-alphamesosaprobic 2,3-<2,7 5-10 <1 4

III strongly polluted alphamesosaprobic 2,7-<3,2 7-13

0,5- several mg/L

2

III-IV very

strongly polluted

alphamesosaprobic transition zone 3,2-<3,5 10-20 several

mg/L <2

IV extremely

polluted polysaprobic 3,5-<4,0 15 several

mg/L <2

For EA GQA dataset the macroinvertebrate results for organic enrichment expressed as Saprobic index are in fact the best mix of family with species resolution data when and where available. Inorganic (Phosphorous) enrichment from Total Reactive Phosphorous Index or TRPI Eutrophication, defined as the enrichment of waters by nutrients resulting in an array of biological changes, is widespread in the lakes and rivers of industrialised countries (Schindler, 2006 and Lampert and Sommer, 2007). Typical symptoms include increased algae production (Walling andWebb, 1992) and sometimes enhanced growth of higher aquatic plants (Dodds, 2006). Traditionally Water Framework Directive (WFD) biological assessment of nutrient enrichment in watercourses has utilised both plant (macrophyte) and benthic algal (phytobenthos) assessments but these have latterly been found to have some flaws for some watercourse types. It has long been recognised that nutrient enrichment causes complexation of ecosystems through changes in primary producers (algae and plants) with studies variably recording e.g. a reduction in faunal (consumer) biodiversity following changes in species composition (Smith, 2003 and Hilton et. al., 2006) and measurable stress to macroinvertebrate communities (Weitjers et. al., 2009 and Miltner, 2010). During the last decade workers have been developing a diagnostic model based upon a Bayesian belief network to detect total reactive phosphorous (TRP) fingerprints from macroinvertebrate community data in receiving watercourses over a wide geographic area of England and Wales (Paisley et. al., 2003, Everall, 2004, Everall, 2005, Everall, 2010 and Paisley et. al., 2011). Eutrophication often occurs in combination with other anthropogenic stresses in rivers in a way that was historically difficult to disentangle, further disrupting simple relationships between nutrient availability and biological response. In the latest TRP diagnostic model developed by the author with Dr. Martin Paisley at Staffs University the benchmark datasets in the model were screened to minimise the confounding effects of organic pollution and split according to site type and season. This is a new biometric developed by Dr. Everall (Aquascience Consultancy) and Dr. Martin Paisley (University of

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Staffordshire) which is based upon the phosphate and macroinvertebrate studies of Paisley et. al. (2003 and 2011) and Everall (2005 and 2006). The Total Reactive Phosphorous Index or TRPI describes the TRP-sensitive taxa groupings in Table 7 overleaf present in a sample and the metric is calculated from the formula below using the ‘look up’ matrix shown in Table 8 overleaf:

ε Nutrient Scores for A & B TRPI = X 100 ε Nutrient Scores A&B&C&D

The TRPI, unlike some previous biometrics e.g. PSI (Extence et. al., 2011) has to allow for both positive and negative changes in the abundance of TRP indicator macroinvertebrate families associated with the findings from large field datasets upon the impacts of TRP in watercourses (Paisley et. al., 2011). Table 7 - Nutrient (TRP) tolerance bandings Group TRP Tolerance Definition

A Taxa very sensitive to [TRP] B Taxa sensitive to [TRP] C Taxa tolerant to [TRP] D Taxa very tolerant to [TRP] E Taxa indifferent to [TRP] at P>0.05 or excluded from the method for

other reasons.

Table 8 - Nutrient scores based on tolerance bandings and abundance Group TRP Sensitivity Log Abundance. Rating (PSR) 1-9 10-99 100-999 1000+ A Very Sensitive 2 3 4 5 B Sensitive 1 2 3 4 C Tolerant 1 2 3 4 D Very Tolerant 2 3 4 5 E Excluded

A tabular ‘look-up’ matrix is then used for TRP indicator macroinvertebrate families from Paisley et. al. (2011) associated with river site Types, season and alkalinity. For example, Type 1-3 are generally associated with upland rivers and Type 3-5 with increasingly lowland rivers respectively. The model calculation formula then generates the season and river type weighted phosphate-sensitive macro-invertebrate metric, the TRPI and a provisional interpretation scheme for the data is shown in Table 9 below. Effectively, the more TRP sensitive families present the lower the

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TRPI% and the less chemical TRP present in the watercourse at that site at that time but recording fingerprint from previous temporal exposure as with and other biometric index. Table 9 - Look up formula results TRPI Nutrient Condition

81 -100 Very low [TRP] 61 - 80 Low [TRP] 41 - 60 Moderate [TRP] 21 - 40 High [TRP] 0 - 20 Very high [TRP]

Biometric section references only

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