UNTREATED SEWAGE AND THE FORAM INDEX: AN ASSESSMENT

Pollution from untreated human sewage is one of several environmental concerns in coastal waters of Belize. This study utilizes foraminiferal assemblage distribution in combination with fecal sterols to determine the presence of human sewage and its effects on a coral reef system off the coast of Caye Caulker, Belize. A total of 125 sediment samples were collected off the coast of Caye Caulker. Fecal sterol concentrations (coprostanol, cholestanol and cholesterol) and diagnostic ratios, grain analysis (mud percent), foraminiferal ecological indices (species richness, density, and diversity), foraminiferal assemblages, and the FORAM Index (FI) were assessed.

Coprostanol analysis showed higher concentrations nearest the eastern shore of Caye Caulker, with lower concentrations found in proximity to the reef; 20 samples had a concentration of greater than 100 ng/g. Cluster analysis and assemblage show that the east and west side are dominated by Quinqueloculina and Asterigerina and these clusters are characterized by relative medium species richness and diversity (28 and 2.66 respectively). The FI indicates that the water quality of the area is conducive to reef growth and recovery. However, 37 samples (out of 125) indicate that the area may be experiencing environmental change (per the FI), and points to the need for further evaluation. Pearson correlation analyses of all variables and samples on the east coast of Caye Caulker show a strong positive correlation between coprostanol-mud percent; and a strong negative correlation between coprostanol-FI, and mud percent-FI. This strongly suggests that raw human sewage does have an effect on foraminifers and on coral reefs.