Diet and isotopic niche dimensions of predatory fish in two estuaries with different degrees of anthropogenic disturbances: a case study of Wami and Pangani Tanzanian coastal estuaries

Diverse anthropogenic activities including alteration of hydrological regime and agricultural development in the upstream river catchments modify structural components ecological roles species estuarine ecosystems. The present study compared diet, carbon (?13C) nitrogen (?15N) isotopic signals, trophic niches metrics redundancy predatory fish their potential phytodetritivore prey-fish between two estuaries with different degrees disturbances. ?13C ?15N Bayesian mixing models stomach content analyses were adopted. It was revealed that diet among predators Arius africanus, Epinephelus coioides, Sillago sihama Pomadasys argenteus signals phytodetritivore-prey, Valamugil buchanani significantly Wami Pangani (PERMANOVA, Pseudo –F ? 3.1, p = 0.05). total niche area accounted by comparable standard ellipse (SEAb) smaller than (t-test, t 4.3, < .001). ANOVA test further confirmed significant variation SEAb populations (F 27.84, 0.001). Layman metric indices diversity estuary substantially those observed at estuary. These findings mean despite being under conservation status, extent disturbances is high enough to induce changes base food web, subsequently cascading its effect up higher-order consumers ecosystem. As a result, ecosystem complexity somewhat compromised relative Therefore, degree affect differently hence overall web structures,