Macroinvertebrate Community Composition in a Constructed Treatment Wetland

M.E. Brown1*, J.W. Lieuw1, C.N. Bonilla1, I.P. Swift1

(1) Natural Treatment Systems, Irvine Ranch Water District, Irvine, CA

Introduction:

o Treatment wetlands are an effective, low-cost water treatment strategy for treating polluted urban runoff prior to entering receiving waters, such as bays and estuaries• They provide habitat since many wetlands have been lost or impaired• Long-term monitoring is important for accomplishing these goals

o Macroinvertebrate (MI) communities have been used to assess water quality• Sensitive to changes not reflected by water chemistry • Respond to impairment1,4

• Base of wetland food web

o Long-term monitoring can be difficult for managers because of time and expertise required• MI usually identified to family level or higher taxonomic resolution• Most metrics were developed for stream systems

Objectives

1. To compare water quality parameters between inlet and outlet

2. To evaluate MI community differences between inlet and outlet

3. To assess whether community differences can be detected at low taxonomic resolution

Results:

Water Quality

Higher DO (P = 0.028; T = 2.5212) and lower TSS (P = 0.0001; T = 7.4116) were noted at the inlet, while lower nitrate/nitrite (P = 0.0033, T = 3.7377), TIN (P = 0.0001; T = 7.8514), and TN (P = 0.0004; T = 5.4686) indicated improved water quality near the outlet (Fig. 1). SPC, ammonia, TKN, and TP were not significantly different for the July-June 2016-2017 period based on dry weather sampling.

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Other InsectaOtherTurbellariaOstracodaAmphipodaOdonataDipteraGastropodaClitellataAcari

Figure 4. Community composition (%) of HD samplers and Active samplers at the inlet and outlet of San Joaquin Marsh in June 2017.

Figure 3. Non-metric multidimensional scaling plot (nMDS) of invertebrate community (4th root transformation; Bray-Curtis similarity) for HD samples (squares) and active samples (triangles) from the inlet (brown) and outlet (blue) of San Joaquin Marsh with taxa (correlation >80%) as axes to separate groups (two-way PERMANOVA).

P = 0.044

Pseudo-F = 3.2929

Figure 2. Abundance, taxa richness, Pielou’s evenness, Shannon diversity, and Average Tolerance Value (TV) in the inlet and outlet of San Joaquin Marsh in June 2017 (two-tailed, unpaired Student’s T-Test). Grey bars represent averages (± 1 SEM; n = 3) from Hester-Dendy samplers, and black points represent values from active samples (n = 1).

Evenness and diversity were higher in the inlet, while average tolerance value (TV) was lower in the outlet. Abundance and richness were not significantly different (Fig. 2).

Community composition was different between the inlet and outlet (Fig. 3, 4).

The inlet was dominated by oligochaetes (55%), and the outlet was dominated by chironomids (82.8%; Fig. 4).

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Figure 1. Average monthly Dissolved Oxygen (DO), Total Suspended Solids (TSS), Total Inorganic Nitrogen (TIN), and Total Nitrogen (TN) at the inlet and outlet of San Joaquin Marsh from July 2016 to June 2017.

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Methods:

o Site: San Joaquin Marsh (SJM), Irvine, CA Pond A = Inlet; Pond 6 = Outlet

• Tributary to the Newport Bay

o Water quality (dry weather flows only)

• Temp., DO, pH, SPC measured weekly using YSI EXO1 sonde

• Monthly 24-hr composites for TSS, ammonia, nitrate/nitrite, TKN, TIN, TN, and TP

o June 2017 – four samples from each inlet and outlet

• 3 “passive” samples: 4 Hester-Dendy colonization plates attached to cinderblock

• 1 “active” sample: 3 one-minute D-frame net (500 µm) sweeps

• Macroinvertebrates (>500 µm) sorted and identified to class, order, or family

Discussion:

Acknowledgements:

Andrew Castillo, Vander Ferrer-Le, Dr. Jason Keller, Michael Mroczek, Sheryl Parsons, Allison Scavo, Stephanie Stragier, Dr. Christine Whitcraft, Noemi Wyss

References:1. Briers RA. 2014. Invertebrate communities and environmental conditions in a series of urban

drainage ponds in eastern Scotland: implications for biodiversity and conservation value of SUDS. Clean. 42(2):193-200.

2. Henriques-Oliveira AL, Nessimian JL, Dorville LFM. 2003. Feeding habits of chironomid larvae (Insecta: Diptera) from a stream in the Floresta da Tijuca, Rio de Janeiro, Brazil. Braz. J. Biol. 63(2):269-281.

3. Pankratz S, Young T, Cuevas-Arellano H, Kumar R, Ambrose RF, Suffet IH. 2007. The ecological value of constructed wetlands for treating urban runoff. Wat. Sci. Tech. 55(3):63-69.

4. Spieles DJ, Mitsch WJ. Macroinvertebrate community structure in high- and low- nutrient constructed wetlands. Wetlands 20(4):716-729.

5. Weston Solutions, Inc. 2008. Stream Bioassessment of the San Joaquin Marsh June 2008 Survey. Prepared for the Irvine Ranch Water District, Irvine, California. June, 2008.

Inlet Outlet

↑DO ↓Nitrate/Nitrite

↓TSS ↓TIN

↑Diversity ↓TN

↑Oligochaeta ↑Chironomidae

o DO is one of the most important predictors of invertebrate community4

• Inlet: higher diversity and taxa richness with lowest TV found (TV = 4)

o Differences in MI community (and in average TV) driven by Oligochaetes (TV = 8) at inletChironomids (TV = 6) at outlet

• Not surprising for urban runoff treatment system3

• Both tolerant of low DO, can be found in slow flowing, organically polluted waters, feed on fine particulate detritus

• Increased chironomids in outlet could be influenced by increased plant matter observed in Pond 6 since they have been shown to eat algae, wood, and leaf fragments2

o Low taxonomic resolution still revealed overall community differences

• 2008 SJM bioassessment found “Very Poor” conditions5

• Not likely that present study would find a different conclusion using similar taxonomic resolution and IBI

Continuing Research

o Comparing macroinvertebrate communities at the inlets and outlets of five Natural Treatment System (NTS) sites

• In situ water quality measurements at each MI sampling location for fine-scale comparison with MI community

• Three 1-minute active sweeps at each inlet and outlet

o Routine MI identifications

• Testing feasibility of horizontal activity traps (HATs)

Carlson Mitigation Area

San Diego Creek

Pond A

Pond BPond 1

Pond 2

Pond 3 Pond 4

Pond 5Pond 6