TITLE:
Influence of Rainfall Pattern in the Seasonal Variation of Fish Abundance in a Tropical Estuary with Restricted Marine Communication
AUTHORS:
Manuel Castillo-Rivera
KEYWORDS:
Constrained Ordination; Delayed Effect; Salinity; Depth; Turbidity
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.5 No.3A,
March
28,
2013
ABSTRACT: Pueblo Viejo Lagoon is an estuary with restricted communication with the sea, so the freshwater influence tends to be more important. Therefore, the study focused on testing the hypothesis that the seasonal changes in species abundance would be mainly related to the local rainfall pattern. Monthly samplings were carried out over a one-year, using a seine net. A total of 9108 individuals were caught, corresponding to 66 species of fish, most of them with marine origin. Canonical correspondence analysis revealed that the rainfall-salinity gradient was revealed to be the most important driving force in the seasonal variation of fish composition. In this way, it was observed that seasonal fluctuations in total fish number were linked to preceding fluctuations (one month) in local rainfall. Similar pattern was exhibited by the abundance of Anchoa mitchilli (the most abundant species), Oreochromis mossambicus and Ariopsis felis, and this delayed effect was significant (cross-correlation analyses). In addition, the rainfall showed a direct influence (significant positive correlations) on abundance of D. auratus and M. martinica. The association between fish number and the rainfall regime seems to be related to lagoon productivity and the trophic responses of these species. By contrast, Brevoortia gunteri and Menidia beryllina showed an inverse correlation with rainfall. Other environmental variables (also influenced by rainfall regime) showed a significant relationship with A. hepsetus (salinity), B. chrysoura (depth) and M. curema (turbidity). Thus, at least 12 species showed some relationship with local rainfall, which accounted for 81.27% of the total number of fish collected. Although it is difficult to separate the relative importance of physiological tolerances and biological functions such as trophic responses, the results suggest that rainfall is a primary factor governing seasonal variation in fish species abundance of Pueblo Viejo lagoon.