Natanya Epstein - The Effects Of Fishing On The Sea Urchin Population Along The Coral Reef In Eilat
Independent Study
Echinodermata echinoidea, commonly known as sea urchins, live on hard bottomed surfaces like coral and feed off of algae and detritus. When settling themselves on the coral reef they bio-erode it often breaking off and killing young coral in the process.
In a balanced coral reef environment the number of sea urchins doesn't supercede the ability of the coral to successfully regenerate but when humans join the picture, organisms from this food chain often get thrown out of balance. In order to look at the impact of fishing on the coral reef of Eilat I snorkeled at two different beaches (one allows fishing and one does not as it is a nature reserve). For five weeks I calculated % cover of live coral, young coral, dead coral, and the absolute density of the sea urchins using a quadrat and underwater clipboard.
Echinodermata are defensive organisms that will paralyze most attackers with a poison kept within their test. This highly evolved defense mechanism limits predation upon them and in the Bay of Eilat their predators consist mainly of Humphead and Broomtail Wrasses and Picasso Triggerfish. Due to the fact that these Wrasses are some of the biggest fish in the area and are very brightly colored the probability of them getting caught by fisher people is higher.
On Tur Yam, the beach that was regularly fished by locals, there were fewer Wrasses, more sea urchins, and less developed coral reef. After undergoing the larval stage sea urchins settle to the sea floor or coral reef and latch on to it scraping off any coral (including young and particularly fragile types). The amount of bio-erosion occurring limits the regeneration rate of the coral reef. The effect of Echinodermata in excess on the reef is to slowly kill it preventing the young coral from ever reaching the reproductive stage which can take anywhere from 2-5 years.
Abstract
Echinodermata echinoidea, commonly known as sea urchins, live on hard bottomed surfaces like coral and feed off of algae and detritus. When settling themselves on the coral reef they bio-erode it often breaking off and killing young coral in the process.
In a balanced coral reef environment the number of sea urchins doesn't supercede the ability of the coral to successfully regenerate but when humans join the picture, organisms from this food chain often get thrown out of balance. In order to look at the impact of fishing on the coral reef of Eilat I snorkeled at two different beaches (one allows fishing and one does not as it is a nature reserve). For five weeks I calculated % cover of live coral, young coral, dead coral, and the absolute density of the sea urchins using a quadrat and underwater clipboard.
Echinodermata are defensive organisms that will paralyze most attackers with a poison kept within their test. This highly evolved defense mechanism limits predation upon them and in the Bay of Eilat their predators consist mainly of Humphead and Broomtail Wrasses and Picasso Triggerfish. Due to the fact that these Wrasses are some of the biggest fish in the area and are very brightly colored the probability of them getting caught by fisher people is higher.
On Tur Yam, the beach that was regularly fished by locals, there were fewer Wrasses, more sea urchins, and less developed coral reef. After undergoing the larval stage sea urchins settle to the sea floor or coral reef and latch on to it scraping off any coral (including young and particularly fragile types). The amount of bio-erosion occurring limits the regeneration rate of the coral reef. The effect of Echinodermata in excess on the reef is to slowly kill it preventing the young coral from ever reaching the reproductive stage which can take anywhere from 2-5 years.
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