Bruce Jermaine O. Trabado, Jessri Paul A. Arguelles Sony T. Sambo (March 2007)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Aside from their intrinsic beauty, mangrove forests are also considered as one of the most productive ecosystems in the world because of the numerous services they provide for many marine and terrestrial organisms. These services include: shelters for spawning, hatching and feeding of many marine organisms such as crabs.
The relationship of a crab and mangrove is mutual. Crabs can eat alien weeds that enter the mangrove community and they feed on the unwanted microorganisms and plankton that live in their water supply. The most common types of crabs that dwell in mangrove ecosystems are hermit crabs, mud crabs and edible true crabs.
Crabs can be generally divided into two separate groups: the hermit crabs and the allies (1400+ species) and true crabs (4500+ species). Hermit crabs are those that have modified nippers for survival, while true crabs seldom get out of the water due to their marine diet.
For the past decades, not only have crabs been common members of the mangrove ecosystem but they’ve also played vital roles in the natural food chain. Without crabs, the natural food chain is altered which may also cause the disappearance of other organisms dependent on crabs for food.
Based on the above facts, the aim of this study are the following: (1) To determine the community structure of crabs in a natural and a rehabilitated mangrove area in Nogas Island, (2) To compare the community structure of crabs in a natural mangrove area against a rehabilitated mangrove area in Nogas Island, and (3) To determine the habitat conditions in a natural and a rehabilitated mangrove area in Nogas Island.
The study was conducted in Nogas Island, Anini-y, Antique, Philippines. A total of two set ups were placed on both areas. A 100m transect line was placed along each area and five 10x10m quadrants were placed along each line 5m apart of each other on alternate sides of the line. Crabs were collected from each quadrant and were classified, then returned to their respective quadrants. Statistical analysis was then applied to the data to produce results.
Overall results showed that there was no significant difference on the community structure of crabs in a rehabilitated and no-rehabilitated site despite of the difference on the environmental factors on both areas.