Disadvantages Of Sea Urchins

The sea urchin (Class Echinoidea, Phylum Echinoderm), is the member of a large group of marine invertebrates, including sea stars, sea cucumber, sea lily and brittle star. Globally, there are approximately 940 species of sea urchins found in all climates, from warm seas to polar oceans. This bottom-dwelling invertebrate occurs in a wide range of a wide range of habitats, including coral reef and seagrass beds.

Sea urchin populations are keystone species in coral reefs and seagrass meadows. They encourage coral recruitment by feeding on algae and opening new reef substrate which is then available for coral spat settlement. For example, in Puerto Rico reefs, those with higher sea urchin populations (> 4 per m²) are associated with higher juvenile

For example, an experiment involved the removal of Diadema populations from a patch of reef carried out by J. C. Ogden in 1972 had showed that species diversity of algae within the reef decreased significantly within 3 months and after 6 months, all coral colonies are killed. However, at high densities, sea urchins will also lead to disadvantages as they appear to be significant bioeroders of coral reef communities by weakening the reef structure by scraping off the coral recruits on hard substrate, as well as prey on living coral tissue. Similarly, in seagrass meadows in the Caribbean Sea, individuals of >20 m² have been shown to cause the denudation of those meadows through overgrazing. Because urchin density reflects the health of marine ecosystem, it is important to study their abundance and monitor population changes to predict and prevent the potential destructive

However, there are no distribution maps of sea urchins, except for the East Coast of Borneo. While many studies have been conducted on sea urchins and their importance in influencing marine ecosystems in other parts of the world, we have very little understanding on sea urchin distribution in Malaysia. Hence, the first objective of this study is to determine the distribution and abundance of sea urchins in Malaysia, as the first step to understand their role in Malaysia marine ecosystem. After all, the next step would be further exploration on the behaviour of these invertebrate as this will provide us a better understanding on how sea urchins interact with marine environment. Sea urchin behaviour is not well-studied in Malaysia, Although the migratory behaviour of a common sea urchins in Malaysia waters, Diadema setosum, has been studied but the home range and movement pattern were not identified, whereas other studies had proved urchins from genera Diadema possess nocturnal movement and feeding occurs only at night. Whilst Diedema setosum is nocturnally active, the movement pattern of Toxopneustes pileolus, from diurnally active genera Toxopneustes, is a widespread and commonly encountered species of venomous sea urchin from the Indo-West Pacific, also remains unknown. The viscera of this species can attract crown-of-thorns sea star (COTS) and could be used to augment population