Threats to Coastal Biodiversity:

1. Resources utilization

2. Developmental activities

3. Natural calamities

4. Global Climatic change

Anthropogenic

Natural

?

Case study on a resource utilization in Gulf of Mannar

Seacucumber Fishery

• Important source of income for fishing communities in South Asia.

• Export commodity in India, generating considerable foreign exchange

• Depletion of stock sizes due to unlimited harvesting, reflecting in the Industry

Government Actions

• from size restrictions on harvest to complete closure of this industry

• In India, size restrictions on harvest was enforced in 1982.

• All species of seacucumber were placed under schedule I of the wildlife Act in 2001,

Current Issue

• There is heavy dependency for this fishery in GOM and Palk Bay

• The issues of the ban got focused to this region

• stock assessments were made in Gulf of Mannar and Palk Bay from 2003 – 2007, reporting low population sizes

Average biomass of each fishery category for the Gulf

Trawl surveys (ZSI)

• Swept area method. A total swept area of 258.8 km2 in a total of 27 trawl tracks, were covered.

• Trawl contents were sorted on-board in-to edible fishes, Trash fishes, molluscs, sponges & soft corals, other Echinoderms, and sea cucumber species. Each category was weighed and noted.

Source of Variation SS df MS F P-value F crit

Total Biomass & Edible fishes 113.05 1 113.05 54.29 0.000 4.03

Total biomass & seacucumber biomass 112.73 1 112.73 46.51 0.000 4.03

Total biomass & trash fishes 88.35 1 88.35 38.38 0.000 4.03

Total Biomass & Echinoderms 66.54 1 66.54 22.57 0.000 4.03

Total biomass & (sponges + soft corals) 130.01 1 130.01 57.24 0.000 4.03431

Total Biomass & molluscs 152.39 1 152.39 75.94 0.000 4.03431

Edible fishes & seacucumber biomass 0.00 1 0.00 0.00 0.983 4.03

Edible fishes & trash fishes 1.52 1 1.52 3.77 0.058 4.03431

Edible fishes & Echinoderms 6.13 1 6.13 5.84 0.019 4.03431

Seacucumbers and trash fishes 1.48 1 1.48 1.99 0.164 4.03431

Seacucumbers and other echinoderms 6.05 1 6.05 4.35 0.042 4.03431

Trash fishes & Echinoderms 1.54 1 1.54 1.22 0.275 4.03431

No relation between total biomass and any of the sorted categories (P ≤ 0.000),

However, significant relation has been observed between edible biomass and seacucumber biomass (P≥ 0.98), and between trash and other echinoderm biomass (P≥ 0.2)

Which indicated that there is severe depletion of valuable fisheries due to excessive demand, causing the non-target biomass dominating the total catch.

Problems Identified

• Methods / Means of Resource utilization

- use of illegal or banned gears

- not adhering to regulations – size restrictions, closure areas etc.,

- enormous by-catch

• Quantity

- over exploitation (no restrictions in no. of trawlers or no. of fishers in a fishing area)

- catching juveniles (no size restrictions

Fishing within RF area of Sundarbans:

• 1,028 motorized crafts and 6,046 non-motorized crafts (CMFRI, 2008)

• 12 + types of nets are used

• Regulations – 1. BLC 2. Annual closed season of 90 days.

Decline in fishery since 1989-90

Depleted stocks of Tenualosa ilisha, Pangasius pangasius, Plotossus canius, and Scylla serrata & PL 20 stages of Penaeus monodon.

Problems Identified

• Methods / Means of Resource utilization

- indiscriminate fishing (non sustainable)

- use of fine nets – wastage of fin-fish seeds

- enormous by-catch

• Quantity

- over exploitation of species such as Tenualosa ilisha, Pangasius pangasius, Plotossus canius, and Scylla serrata & PL 20 stages of Penaeus monodon.

- catching juveniles (no size restrictions)

Extent of utilization

• Gulf of Mannar: 50,000+ people involve about 850 trawlers, 7400

small-scale fishing vessels (SFV), and 300 catamarans for fishing and allied fisheries (Gopakumar, et al., 2011). About 5000 women are involved in harvesting seaweeds, ~4500 divers are collecting sea cucumbers, of which ~1000 are also involved in chank (Turbinella pyrum) collection (Rajagopalan, 2011).

• Sunderbans: The marine fisherfolk (population of 2,69,565), with an

active fisher population of 70,750, located in 237 villages operate 6,205 mechanized crafts 1,028 motorized crafts and 6,046 non-motorized crafts.

• As the case of indiscriminate exploitation, corals had been heavily quarried for limestone, beginning in the early sixties (Pillai, 1996) and continued clandestinely until recently as 2002. During 60’s an estimated 3000 to 4000 turtles were caught annually in GOM and Palk Bay (Rajagopalan, 1984). 106 Tons of gorgonians had been exported from 1975-1992 (Venkataraman et al., 2002). In addition, large numbers of sea urchins, brittle stars, sea lilies, sea anemones and 60 species of ornamental fishes as aquarium animals are also known to be exploited (Venkataraman et al., 2002).

Measures:

• Existing resource utilization practices need to be converted into sustainable fishing practices

• Sundarbans – Identifying practices of lesser impacts on biodiversity – included in the guidelines

• Gulf of Mannar – awareness among fisher-folk to complying no-take-zones.

– collaborative initiative to the enforcement of MFRA, 1983 & 2000.

• General Applicability – Periodical monitoring of stock sizes and population structures for decision making and resource utilization

Impact of Developmental activities vis-à-vis localized stressors

CRZ Violations - Garbage dumping, untreated sewage and industrial waste disposals

Agricultural runoff - leading to nutrient enrichment and thus algal dominated reefs

Sedimentation through land based activities

Mangrove felling - increased sedimentation into marine systems, shore erosion, loss of dependent species

Indicators

• Reduction in species abundance

• Increase in biomass / dominance of stress tolerators

• Reduction in biomass of key species /valuable species

• Reduction in ecosystem functions /services

Dominance of stress tolerant species of corals in Gulf of mannar reefs shown by their percent cover

Natural calamities

• Cyclones-

• Earthquakes – uplift of mangroves and coral reefs in Andamans due to

landmass uplift – shore erosion due to land subcedence

• Floods – debris and sedimentation into coral reefs and mangroves

Assessment of Reef Area Loss and Implications on Scleractinian sp. Diversity on Coral Reefs Affected by Terrace- Uplift; Aftermath of the December 26th 2004 Earthquake, in Andaman Islands, India. Rajkumar Rajan1, Satyanarayana Chowdula2, Rajan Ponnamkulam1 1Zoological Survey of India, National Coral Reef Institute, Port Blair, Andaman Nicobar Islands, 2Zoological Survey of India, General Non-Chordata Section, F. P. S Building, Indian Museum Complex, Kolkata

Eleven fringing reefs in North Andaman Islands, devastated due to landmass uplift (~ 1

m) following the Earthquake on 26 December 2004 . off southern Sumatra coast, were

surveyed for: (i) estimate of reef area loss (ii) Scleractinian sp. mortality, and (iii)

diversity and percent cover on the existing reef slope and within the depth of 10 m.

The uplift caused the reef crest and part of reef slope in

these reefs to be totally exposed, with the estimated loss of

30% of reef area. Loss of reef area was found to be varied between reefs,

arbitrated by the uplift and characteristic of reef morphology, and not in proportion to

the total reef area (pre-earthquake) in each reef. LIT surveys revealed that exposed

reef areas possessed high coral cover i.e., 89.8 ± 2.62%, (killed Scleractinians only), as

against the 37.92 ± 21.83% in the unexposed/existing reef zones. The high variation in

percent cover in the existing zones attributes to the variation inpercentage of loss of

area in each reef: reefs heavily impacted exhibited lowerpercent cover in the existing

reef zones. Exposed areas showed higher diversity (Simpson 1/D = 2.33), in the

heavily impacted reefs only; other exposed areas showed only species dominance.

Existing reef zones obtained slightly lower indices (1/D = 1.75 ± 0.19), however with

relatively high evenness (E = 0.53 ± 0.13). These analyses point out that, the reef

cover lost - in proportion to the percentage of loss -

manipulated overall species diversity and dominance in

these reefs. Loss of dominant species cover (via the exposed areas) will be

discernible in the restoration processes as existing reef zones do not exhibit similar

species structure. Monitoring studies may, in this case, indicate the influence of other

external stressors consequent to the uplift.

Climatic impacts

• Loss of species - Bleaching loss of coral cover

• Stunted growth of mangroves

• Frequent natural calamities

• Physiology of animals due to local rise in temperatures – life cycles, low fecundity etc.,

Climatically induced rise in SST caused bleaching in Lakshadweep corals

Average of live and bleached coral % covers in the 8 zones in Andaman Nicobar Islands during the bleaching event in May 2010

Managing coastal ecosystems and conservation of

biodiversity depends on knowledge on impact on biodiversity and its inclusion in the management guidelines

1. Identifying as well as quantifying pressures due to developmental and social activities is the first part.

2. Devoted long-term monitoring of the biodiversity of critical coastal habitats for interpreting the impact of unexpected events

3. Address social problems by understanding the availability of resources and the long-term sustenance of resources.

4. Facing global threats should evolve from the understanding of resilience of coastal ecosystems to frequent and persistent global threats.

• Thank you