An investigation on the effects of mine tailings on the coral reef ecosystem of Calancan Bay in Sta. Cruz, Marinduque, was to establish the veracity of local fishermen’s complaint about the decreasing fish productivity.
Physico-chemical and biological analysis of seawater, fish, benthic, and plankton samples were carried out. The results indicated a deteriorating environment. Sample of the tissues were also subjected to analysis by atomic-absorption spectrophotometer at the National Pollution Control Commission laboratory. Concentrations of heavy metal ions in fish flesh were found to be within permissible limits.
Underwater survey of coral reef formations by SCUBA divers disclosed the presence of dead colonies of soft corals and invertebrates in all sampling stations.
The adverse effects of mine tailings on the fishery resources of Calancan Bay were confirmed by the decreased number of fish population and diversity in the area. Only 108 species of fish were confirmed to be present in the reefs.
The one flourishing anchovy fishery was replaced by glassfish. These shifts in species composition and structure in the coral reef ecosystem suggest a stressed environment.