Resumen de Foraminifers of Guayanilla Bay and their Use as Environmental Indicators
Samples were taken at thirty-two stations in Guayanilla Bay to study the living and dead microfauna. Foraminiferal populations were compared with populations of Mayagüez, Jobos and San Juan Bays, the sound east of Ponce Bay, and Mar Negro, La Torrecilla, Piñones and Cabezas de San Juan Lagoons. The ratios of the number of nematodes to living formanifers are lower in Guayanilla Bay than in Mayagüez and Jobos Bays. This is probably related to chemical pollution in Guayanilla Bay.
Fursenkoina punctata is dominant in the deepest part of Guayanilla Bay. Compared with populations from other areas of Puerto Rico, three different forms are described, one of them related to pollution. The mean length against the mean ratio of length to width of individuals is plotted on a scatter diagram. The dimensions plotted in the upper left part of the diagram correspond to foraminiferal populations in unpolluted areas while the dimension plotted in the lower right corresponds to populations in polluted areas.
Ammonia catesbyana is the most abundant foraminifer in the study areas. Three forms are found in Puerto Rican waters: forma typica, forma tepida and a high-spire form. Some populations of forma tepida are related to chemical and thermal pollution. A small percentage (5%) of populations under chemical and thermal pollution are deformed. The high-spire form occurs in environments under stress conditions with abundant organic matter. All or most specimens of this form are megalospheric and under extreme conditions of organic pollution have a giant protrunding proloculus. A. catesbyana is the species most resistant to pollution.
Quinqueloculina rhodiensis develops two abnormal forms, one under thermal pollution and another under organic pollution. Ammobaculites salsus has deformed chambers under thermal pollution.
Florilus grateloupii and Cribroelphidium poeyanum have low resistance to pollution. A core taken at warm water lagoon (Guayanilla Bay) shows populations prior to thermal pollution where C. poeyanum is the dominant form. It has practically disappeared at present on account of thermal pollution.
Through the study of the vertical microfaunal change in a core the environmental history of a bay or a lagoon may be reconstructed and under some circumstances the future development may be predicted.
