Freshwater Biodiversity of Sri Lanka

Submitted To:

Mr. Abdul Qadir

Submitted By:

ShamimMukhtar 13

BS (Hons) IV (E)

College of Earth and Environmental Sciences

University of the Punjab

ContentsSri Lanka......................................................................................................................................................4

Freshwater biome.......................................................................................................................................4

Biodiversity..................................................................................................................................................5

The Freshwater Fishes in Sri Lanka..............................................................................................................6

Turtles and Tortoises of Sri Lanka................................................................................................................7

Freshwater crabs.........................................................................................................................................8

Common commercial fish............................................................................................................................8

Crustaceans.................................................................................................................................................9

Molluscs......................................................................................................................................................9

Echinoderms................................................................................................................................................9

Vegetation in Fresh water bodies/swamps.................................................................................................9

Why a freshwater biodiversity network?....................................................................................................9

Why Freshwater biodiversity matters.......................................................................................................10

Recommendations.....................................................................................................................................10

References.................................................................................................................................................13

Sri LankaSri Lanka is an island located in the tropical belt close to the

equator between 5°.55’- 9°.50’ and 79°.42’- 81°- 52’. Sri Lanka is an island with a land area of 6,570,134 ha and a coastline of 1,600 km. The island consists of a broad coastal plain and a central mountainous area rising to elevations of 2,500 m. This altitudinal change has caused thermal zones and the variation in rainfall and altitude has resulted in a wide variety of terrestrial ecosystems. Additionally, there is yet another multitude of ecosystems in the coastal and marine areas.

The population of Sri Lanka is 20.48 million (2013), with a density of 292 persons per km2. The population growth rate is 1.1 per cent/year; adult literacy rate is 89 per cent and average life expectancy at birth is 72 years (males) and 76 years (females).

In terms of species, genes and ecosystems, Sri Lanka has a very high biodiversity and is one of the 34 hot spots in the world.

The fauna and flora of Sri Lanka have generally been considered an extension of that of southern India, especially the southern Western Ghats, the range of mountains that borders the western littoral of the Indian peninsula (Myers et al., 2000). It has been widely recognized that the Western Ghats and Sri Lanka are “strikingly similar in their geology, climate, evolutionary history, and biodiversity” (Mittermeier et al., 2000: 353). The western Ghats-Sri Lanka region is now treated as a Global Biodiversity Hotspot, given that it has lost more than 70% of its original habitat and contains the required minimum 0.5% of Earth’s vascular-plant species endemic to it (Myers et al., 2000; Mittermeier et al., 2004).

Freshwater biome

Freshwater is defined as having a low salt concentration — usually less than 1%. Plants and animals in freshwater regions are adjusted to the low salt content and would not be able to survive in areas of high salt concentration (i.e., ocean). There are different types of freshwater regions:

Ponds and lakes Streams and rivers Wetlands Floodplains

There are no natural lakes in Sri Lanka; instead many reservoirs and tanks are located in the dry zone, highest numbers reporting in Anuradhapura and Kurunegala districts. However there are over 12,000 manmade lakes in the island. Some of these water resources are perennial while others are seasonal, however many are interconnected since they have been developed according to a cascade system. Among 10,000 reservoirs and tanks identified 3500 are significant. There are 103 perennial rivers (9 major and 94 minor) radiating from the central highlands, covering an area of 59,217 hectares.

BiodiversityBiodiversity is the variety of different types of life found on earth. It is a measure of the variety of

organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation (number of species) within an area, biome, or planet.

Sri Lanka has one of the highest rates of biological endemism (16% of the fauna and 23% of flowering plants are endemic) in the world even though it is relatively small. Sri Lanka’s freshwater biodiversity contains

91 species of freshwater fish, and 50 of which are endemic to the country 8 species of brackish water fish that also come to freshwater 24 introduced exotic fish species 246 land gastropods 28 species of Cetaceans Freshwater snails 7 species of tarantulas 16 species of Poecilotheria 100+ species of common commercial fish Molluscs Echinoderms 3 species of freshwater turtles and one terrestrial tortoise 51 species of freshwater crabs Freshwater bivalves 88 percent of the flowering plants, and 95 percent of country's flowering plant endemics 39 Amphibians 1 Crocodilians

The Freshwater Fishes in Sri Lanka

The fish in this country fall into three main categories.

1. Indigenous fresh water species – these are fish that live in freshwater right through their life. This category has 44 endemic species.

2. Those species that live in brackish water lagoons and deltas in the coastal areas. They also, in some instances, live in fresh water habitats. For example, some eels are born in the sea but soon after come and spend most of their lives in fresh water. They go back to the sea later, where they breed and later die.

3. The species that live in marine water throughout. However, in rare instances some of these species have been recorded in fresh water as well. They may be brought in by the influence of the tides. (Jayawardene, 2015)

IntroductionSri Lanka supports a rich freshwater fish assemblage that comprises of 91 species including 50

endemics (Bailey and Gans, 1998; Goonatialke, 2007; Silva et al., 2008; Meegaskumbura, et al., 2008; Pethiyagoda, 1991; Pethiyagoda et al., 2008; Pethiyagoda et al., 2008a; Pethiyagoda et al., 2008b; Pethiyagoda et al., 2008c; Silva et al., 2011; Pethiyagoda et al., 2012; Watson, 1998). Other than these indigenous species, 24 exotic species have been introduced to the island, mainly to boost the inland fishery (Goonatilake, 2007). Senanayake and Moyle (1982) have identified four major Ichthyological zones (Southwestern, Mahaweli, Dry and Transition) according to the distribution patterns of freshwater fish in Sri Lanka. Out of these four zones, Southwestern and Mahaweli zones bear the highest freshwater fish diversity in the island.

DistributionSenanayake and Moyle (1982) have proposed four major Ichtyological zones (Southwestern, Mahaweli, Dry and Transition) based the on distribution pattern of freshwater fishes. Of these the South Western and Mahaweli zones support the highest diversity in freshwater fish while the Dry Zone species have a higher affinity with the freshwater fish in the Indian peninsula. Number of species such as Pethia bandula (Minipura at Kegalle District) and Stiphodon martenstyni (Atweltota near Matugama) and Rasboroides nigromaginata are only known from a single location (point endemics). Further, some species such as Dawkinsia srilankensis, Laubuca insularis, Systomus martenstyni, Labeo fisheri and Labeo lankae are only known from a single river basin. However, species such as Lepidocephalichthys jonklaasi, Devario pathirana, Rasbora wilpita which were also thought to be restricted to a single river basin, namely the Nilwala basin, have been shown to occur also in the Kelani river basin.There are 174 species of freshwater fish included native, endemic, introduced and not established. Few of the orders are:

Order Family Species Status FB name Name

Cypriniformes Balitoridae Acanthocobitis urophthalmus

endemic  Banded mountain loach 

Vairan ehirava 

Perciformes Sparidae Acanthopagrus berda

native  Picnic seabream 

Thiraliya 

Anguilliformes Anguillidae Anguilla nebulosa

native  Mottled eel  Pol mal aandha 

Cyprinodontiformes

Aplocheilidae Aplocheilus panchax

native  Blue panchax  Hande titteya 

Siluriformes Ariidae Arius subrostratus

native  Shovelnose sea catfish 

Ura anguluva 

Clupeiformes Engraulidae Coilia reynaldi native  Reynald's grenadier anchovy 

 

Beloniformes Hemiramphidae

Hyporhamphus limbatus

native  Congaturi halfbeak 

Marandha 

Syngnathiformes Syngnathidae Ichthyocampus carce

native     

Elopiformes Megalopidae Megalops native  Indo-Pacific Illeya 

cyprinoides tarpon 

Salmoniformes Salmonidae Salmo trutta trutta

introduced  Sea trout   

Tetraodontiformes Tetraodontidae Tetraodon nigroviridis

native  Spotted green pufferfish 

 

41% of all known species of fish of Sri Lanka are found in freshwater. There are about 70% of endemism of those fish. Most of them are listed into IUCN categories:

Freshwater eels Carps and allies River loaches True Loaches Naked catfishes

 Sheat catfishes  Airbreathing catfishes

 Airsac catfishes Swamp eels  Rivulines

 Ricefish Cichlids Climbing perches Gourami Snakeheads

 Garfishes Sleeper gobies Spiny eels Gobies

Turtles and Tortoises of Sri Lanka

DIFFERENT SPECIES: Today there are 250 species of turtles on earth. Seven of these live in the ocean and are called sea turtles. The remaining 243 species live on land or in freshwater ponds and marshes. The terrestrial turtles, those that live solely on land, are called tortoises.

Five of the seven species of sea turtles in the world visit the shores of Sri Lanka to breed. They are the Green Turtle (Chelonia mydas), Hawksbill Turtle (Eretmochelys imbricata), Olive Ridley (Lepidochelys olivacea), Loggerhead (Caretta caretta) and Leatherback (Dermochelys coriacea). The sea turtles are called Kesbawa in Sinhala and Amai in Tamil.

There are three species of freshwater turtles and one terrestrial tortoise in Sri Lanka. The freshwater turtles are Parker’s Black Turtle (Melanochelys trijuga pakeri) Sri Lanka Black Turtle (Melanochelys trijuga thermalis) and the Soft or Flapshell turtle (Lissemys punctata punctata). The terrestrial tortoise is the Star tortoise (Geochelone elegans). (Jayawardene, 2015)

Galapagos tortoisesphoto licensed under CC BY 2.0 by Dallas Krentzel

Freshwater crabsSri Lanka supports a rich freshwater crab

assemblage in comparison with other similar, well studied tropical Asian countries such as Peninsular Malaysia and Singapore, which together have a territory about twice the extent of Sri Lanka, and yet about the same number of freshwater crab species (Ng, 1988), while Taiwan which is about little over half the size of Sri Lanka (36,000 km2) has 34 species (Ng et al., 2001). Another unique feature of Sri Lankan freshwater crabs is that they show 98.04% endemicity which has not been observed in any other faunal group in Sri Lanka.

Sri Lanka's freshwater crab fauna is extremely important to the island, due to its endemism. All recorded 51 species, along with five genera, are totally endemic to Sri Lanka. 98% of those crabs are IUCN categorized as threatened, endangered or critically endangered animals.

Phylum: ArthropodaSubphylum: Crustacea 

Order: Decapoda.

All the Sri Lankan freshwater crabs belong to a single family, Gecarcinucidae.

Common commercial fish

Marine fish are strictly different from freshwater counterparts due to high salinity of sea water, which they live. Also, they are larger than most freshwater species and rich in proteins.

There are about 100+ species of common commercial fish around the country. 

Crustaceans   Crustaceans such as, crabs, lobsters, prawns, and squids, cuttlefish, and sea cucumbers also added

to this list instead of fish types due to their high value commercially.

MolluscsClass: Cephalopoda

Order: Teuthida

Family: Loliginidae

Echinoderms

Class: HolothuroideaOrder: Aspidochirotida

Hawksbill Turtle (Eretmochelys imbricata)photo licensed under CC BY-NC-SA 2.0 by Kevin Bryant

Family: Holothuriidae

Vegetation in Fresh water bodies/swamps

The coastal and freshwater wetlands are characterised by young and unstable soils. In the northern and southern dry zones/ Hambantota, Jaffna/ Mannar and Puttalam areas/ are found solodized solonetz and solonchanks (saline soils). These soils/ found along the coast/ tidal flats and flood plains inassociation with other soil types/ are rather brownish or yellowish, saline and alkaline.

In the coastal areas mangroves and salt marshes colonize inundated bays/ inlets and river estuaries with scrub vegetation invading sandy shores and dunes. Inland areas inundated by fresh water have swamp and floodplain forests. Mostof these have been converted to paddy land.

Why a freshwater biodiversity network? Fresh waters reflect all of the ecological and human-related processes that take place within their

catchments. They are highly vulnerable to land use (e.g. erosion and sedimentation), and their condition provides early warning of landscape degradation. As the arteries and kidneys of the landscape, they carry water, nutrients and sediments; they drain and purify wastes, as well as produce a plethora of resources used by human societies. Of all the world's global ecosystems, freshwaters are under most pressure. Freshwater ecosystems are declining globally in extent and number, some at dramatic rates; as a result, threats to freshwater biodiversity are particularly severe.

Freshwater ecosystems support one of the highest levels of species richness. For example, fish species living in fresh water represent one quarter of global vertebrate diversity.

The role and relevance of freshwater biodiversity to ecosystem functioning and for the provision of services have not been adequately assessed (Naiman, R.J. et al., 2006)

Why Freshwater biodiversity matters1. According to Naiman, R.J. et al., (2006) Fresh water – and the biodiversity it supports - is of vital

importance to all life and to nearly any kind of human activity, including industrial production, navigation, domestic water requirements, waste assimilation, health, and especially food production.

2. Many serious human diseases are water-borne or spread through aquatic vectors (e.g. malaria, schistosomiasis, onchocerciasis, cholera, dysentery). The incidence of water-borne diseases is increasing as disease agents are easily dispersed through poor water management and pollution -- being directly or indirectly a consequence of biodiversity modification. Anthropogenic modifications of freshwater systems reduce natural biodiversity and favour one or a few species that can often become, according to the geographic area, pest species (e.g. Simulium spp, biting blackflies) or disease vectors (e.g. mosquitoes, snails).

3. Clean fresh water is a limiting resource for development in many regions of the world. Therefore, the role of biodiversity in freshwater processes (e.g. self-purification) is of crucial importance for sustaining goods and services for human populations.

4. Freshwater biodiversity and ecosystems provide aesthetic, cultural and spiritual values. Traditional spiritual values and sacred places (e.g. in South Africa, India, Cambodia, Sri Lanka, Australia) are strongly associated with natural freshwater sites and their inherent biota. Finally, the psychological and recreational values of natural freshwater systems such as fishing, swimming, hiking, boating, and rafting, as well as the creativity associated with music, painting and poetry, are paramount.

5. Freshwater biodiversity supplies essential goods and services to human populations. They include:

a. Commercial, recreational and subsistence fisheries, and wildlife hunting; .Wood, reeds and medicinal plants for construction, weaving and health care; .Supplies of nutrients and carbon sources to sustain terrestrial and marine productivity (e.g. near-shore finfish, salmon and prawn fisheries, coastal aquaculture, floodplain agriculture and grazing systems).

6. Freshwater faunas show a high degree of endemicity as shown, for example, by the outstanding examples of species flocks of fishes in ancient African lakes. In general, strictly aquatic taxa, such as fish and bivalves, are usually isolated within river or lake catchments providing opportunities for radiative adaptation and speciation. However, such endemicity makes them vulnerable to changing conditions and their disappearance is more likely to lead to disappearance of ecosystem goods and services.

Recommendations1. A conservation assessment of the freshwater fauna is overdue, but for most species up to date

information on populations and trends simply does not exist to facilitate one. A comprehensive assessment of the populations of all freshwater fish species based on fresh sampling is therefore an urgent necessity.

2. While fisheries managers maintain detailed catch records at several stations in Sri Lanka, taxonomic data are not acquired. The maintenance of records of the catch of each species, especially the indigenous-species by-catch, could provide a means to make trend analyses that could inform future conservation decisions.

3. All pesticides approved for release in Sri Lanka should be assessed for impact on non-target organisms and the environment in general, and the labelling of such products should include information on environmental safeguards.

4. All future releases of exotic fishes should be preceded by an environmental impact assessment involving specific safeguards against invasiveness.

5. A positive list of organisms that may be imported by the ornamental fish industry needs to be developed and enforced.The necessary legal provisions for this already exist in the Fauna and Flora Protection Ordinance.

6. Legal and institutional reforms need to be made to engage local communities in the in situ conservation of point-endemic freshwater fishes; and to engage the ornamental fish industry in ex situ conservation, especially the development of methodologies to breed “difficult” threatened species (e.g. Puntius asoka) in captivity.

7. International agencies, particularly the FAO and ADB should be informed of the negative consequences of their fisheries development projects in Sri Lanka and urged to engage in supporting the research and capacity-building necessary to manage the fishery sustainably into the future.

8. Incentives and regulatory measures need to be introduced to phase out, over a defined time scale (say 2-3 years), the harvesting of fishes from the wild by the ornamental fishery, while encouraging the culture of such species as for which there is commercial demand.

9. Finally, although its consequences will have minimal conservation benefit at this stage, the Department of Wildlife Conservation should take steps to eradicate the last population of rainbow trout in Sri Lanka.

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