Bioaccumulation of run-off pollutants: An evaluation of marine sponges as bioindicators

Runoff and sewage discharge present serious consequences if left unchecked in coral reef ecosystems. Eutrophication and the introduction of harmful chemicals to the environment can lead to the destruction of coral reefs. Phosphates and polycyclic aromatic hydrocarbons (PAHs) are well known components of runoff that are detrimental to the reef ecosystem. As such, the ability to monitor the concentration and spatial distribution of these chemicals is of great interest. These pollutants may be detected using bioindicators. Bioindicators are organisms that can be used to monitor the health of an ecosystem. In this study, sponges were assessed as bioindicators for phosphate and PAHs in coral reef environments. Holopsamma helwigi, Ircinia strobilina, and Pseudoceratina crassa are common Leuconoid sponges that were tested for pollutant contaminations using fluorometric analysis. The sponges were collected along a transect spanning the northern coast of Kralendijk, Bonaire. A known runoff site at ‘Kas di Arte’ (12° 9' 19.9362" N, 68° 16' 44.5434" W) was selected as the starting point for the transect. The sponges bioaccumulated both phosphates and PAH compounds. Concentrations of the pollutants were not found to decrease as the distance from the runoff site increased suggesting that sponges assessed here are not capable of showing short-term variation in spatial trends of pollutant concentration. In order to better understand how the sponges accumulate pollutants, a thorough exploration of the kinetics of pollution bioaccumulation should be pursued in future studies.

This student research was retrieved from Physis: Journal of Marine Science XV (Spring 2014)19: 45-51 from CIEE Bonaire.