in Sri Lanka - Ministry of Environment

DistributionMany Marine species including the Crustacea reproduce through release of eggs and larvaeinto the water column. The duration of time the larvae spend drifting in the ocean as plankton,existing pattern of currents and the ability to find a suitable substrate for settlement will dictatethe rate of dispersal of the species. Under favourable conditions sedentary species may crossdeep oceans to settle on distant shores regularly. In addition to the demersal species, theCrustacea contain a large group of taxa that inhabit the Pelagic or open seas as part of thePlankton or Nekton throughout their lives and may inhabit and traverse large expanses ofOceanic waters and shores. Therefore, many marine species display wide distribution patternsoccupying similar habitats across the region. Further, dispersal strategies of most marinespecies and the lack of hard ecological barriers prevent the establishment of endemic speciesin the marine environment.The Palk Strait and the Gulf of Mannar represent a shallow and narrow stretch of sea betweenthe shores of Southern India and Sri Lanka. The general homogeneity of habitats across theshores of the two countries and their close proximity would make it highly probable that bothshores would harbour a similar species assemblage.ThreatsCrustacea include species of commercial interest both as local food species and exploited forthe export trade both as food and Ornamental species. While harvesting of Shrimps, Prawnsand Crabs for local consumption is high, the most severe exploitation of Crustaceans occurdue to the export industry. The spiny lobster fisheries take place around the shores of SriLanka and have a significant impact on the wild populations. The population densities onexploited reefs have depleted significantly and on occasion they have reached near-extinctionlevels on certain reefs. Though regulations are in place for some species the populationsare on the decline due to inadequate enforcement. The collection of high value ornamentalspecies is causing significant reduction of reef Shrimps, Crabs, Hermit crabs Mantis shripmsand Lobster species. The excessive collection of reef shrimp species that play an importantrole on the reef as cleaners of other species can result in a reduction of health of reef faunaand abandonment of sections of the reef by other animal species affecting the balance ofthe eco-system. However, habitat loss, including the degradation of coral reef environments,probably pose a greater threat to Marine Crustacean Diversity than that of direct extraction.ConservationSeveral species of Marine crustaceans are currently listed as Protected under the Fauna andFlora Protection Ordinance. These include the Painted/Harlequin/Orchid Shrimp (Hymenoceraelegans), Scarlet/Reef Lobsters in the genus Enoplometopus (E.ocedentalis ,E. debelliusand E.holthuisi) and the Hairy-red/ White-spotted Orange Hermit-Crab (Dardanus megistos).However, providing legal protection to many species has not had a significant impact as onsite enforcement is ineffective. Therefore, the unregulated harvest/extraction of many speciesof crustaceans tends to have significant impacts on their populations.397