Reef and seashores island of Lakshadweep Biodiversity and different ecosystems of Lakshadweep Lakshadweep Islands Lakshadweep is group of islands- coral atol island – western coast of india- 400 km from kochi -30 to 32 islands – submergered and emergered coral atoll islands- 10 island is inhabitats 32 square kilometer As of 2011 the population of the union territory of Lakshadweep is 65000 people Lakswadeep Mostly consist of Long and narrow islands which are Oriented in the north to south axis. The Strong annual southwest monsoon causes the western side of Lakshadweep atolls to form large shallow lagoon with average depth of 2 meters and eastern side of the atoll accumulates sand and forms terrestrial land. The western shores of Lakshadweep atoll has white sand beach where as the eastern shore of the Lakshadweep atoll mainly consist of rubbles which are mostly broken exoskeleton of corals made of calcium carbonate. Lakshadweep island dominated by coconut trees- one of the densest concentration of coconut per unit area tree s in world Wildlife Mostly introduced- cats, rats, barn owls, Black shouldered kites Resident bird- plover, whimbrels, sandpiper, gulls, Carbs- red eye crabs, ghost crab, Lagoon- western side- large shallow coastal water- enclosed with in outer reef ring- 3-4 meter deep in Lakshadweep Lagoon – has corals – serves refuge or nursery habitat for fish Corals- provide physical structure -attracts fishes – protection from predatorsOuter reef- ring of coral- protects the island and coast from wavesOuter reef is more diverse than patch reef inside the lagoon Western reef has a smooth slope – eastern reef form cliffs after 10 m from the shore Coral atoll Coral atoll is a ring of coral reef and generally has shallow lagoon in the middle. Coral atolls are formed by long extinct volcanos, as the volcano goes dormant, corals starts growing around the volcano and over time the coral reef grows larger and the volcano starts to sink beneath the water surface, and this forms a lagoon in place of the volcano and a ring of coral around it. Remains of extinct underwater volcanos- starts to grow corals around it- sand collects within the ring of coral and forms island In Lakshadweep there are 2 major order of coral, that is Alcyonacea and Scleractinia. 2 major order of coral1.AlcyonaceaThey are soft corals. Unlike hard corals they don’t secrete calcium carbonate and they don’t have hard exoskeleton. Sea fans and sea whips are some of the coral species in the order Alcyonacea 2.Scleractinia Scleractinia are hard corals, consisting of many coral polyp. They secrete calcium carbonate and form a hard exoskeleton. The coral polyps Settles on reef substrate- divide and clone Symbiotic-with unicellular algae-zooxanthale- gives their color Secretes caco2-base for growth of more corals- structure and protection for reef fish ecosystem- dead exoskeleton eroded into sand – form the island within atoll Corals starts- thin crust or flim on the surface(some stays that way)Coral structures Table coral- table shaped coral Foliar or leaf like coral Arborescent or tree like coral Boulder shape coral Fungi like coral Most species- change the growth form depending on the environmental conditions- can be any of these shapes Growth form varies by the amount of caco2, fagility, and micro habitat Branching from provides higher more area or structural complexity for juvenile fishes to hide- more suseptable to bleaching Boulder coral- don’t provide structural complexity- more resistant to bleaching Threats- natural n manmade Natural-competition for space with algae n other corals -attacked by polychaete worm- Christmas tree worn-drill into the coral- these holes provide shelter for some fishdiseases- pink spot-spread by butterfly fish vector mammade- climate change- too warm for too long- expel zooxanthale- survive for a few months-if the zooxanthale isn’t taken back the coral dies- too long – mass bleaching event- whole reef can die mass bleaching even- 1998- catastrophic for Lakshadweep- lost over 90% of its reef fish diversity in Lakshadweep: -due to less human interaction, reef fishes of Lakshadweep are more fearless of humans -fish population in Lakshadweep has remained stable as of now high diversity- clear water-no sediment- higher visibility than other reefs in india categories of fish planktivore -feed on plankton- by filtering water- fusiliers, anthias, unicorn fish Herbivore - sergeant fish, rabbit fish -eats macroalgae n turf algae, ingest -parrot fish- take chucks of dead coral, scraped the turf algae in the surface- crush the coral in their gut- digest the algae- excretes the powdered caco2 as sand- important in sediment production- 80% sand in Lakshadweep is parrot fish excretion-estimation -without herbivore reef will get dominated by algae- allow junvanile algae to settle on the ground Micro invertebrate feeders -damsel, butterfly n angle fish -damsel fish are also called as famers of reef ecosystem as they aggressively defend patches of reef from herbivores, these patches get dominated by turf algae. they farm the algae so that they can eat the invertebrates feeding on the algae- larval stage of crustaceans and arthropods -butterflyfish- has pointer snout- feeds on individual coral polyps Predator -grouper, lion fish, black snapper, shark, moray eel, -the adult individuals are apex predator, other stages lies in the middle -sharks aren’t common- historic fishing pressure- give birth to live young, limits the no of offsprings Overtime many Corals form complex relation with other reef fished and crustaceans- shrimp Pocillopora- many bumbs on the coral – even animals living in the coral has bumps (crab)- has skin pattern similar to the coral(hawk fish)-Yellow spotted scorpion fish- only found in pocilliopora Sea anemone grows on coral - stonefish- well camouflaged -honey comb morae eel- look like the coral- camofleged -mimics more dangerous species, sea cucumber mimicking more poisonous sea slug - snake eel mimics yellow lip sea krait -fish change colour to match colour of other fish- forms large mix species shoals - helps them escape predators Cleaner wrasse- feeds on exoparasites - fish comes to cleaning station to get claned from exoparasite- they also take bites of flesh from the fish as they clean, this is their main source of food -some fish change to a lighter colour so that its easier to spot the exoparasite and changes back to their darker colour once done. Fishing in Lakshadweep -reef fishing isn’t common in Lakshadweep -tuna is the most fished in Lakshadweep, as they have a circumtropical distribution, short life cycle and faster growth, it is more sustainable than catching reef fishes. tuna are schooling fish and they swim with their mouths open and feeds on everything that they catch -local fishermen- by dumping many small bait fish and they have a sprinkler in the back of their boat which triggers the tuna to start feeding, the fishermen then use a fishing line with no bait, it only has a hook to catch the tuna, the tuna grabs the hook and is pulled out. This form of fishing has no bycatch and only targeted to tuna.
