Feeding competition between two goby species, Pomatoschistus lozanoi (de Buen) and P. minutus (Pallas), in a macrotidal satmarsh.

Abstract

Two transient goby species (Pomatoschistus minutus and P. lozanoi) occurred in saltmarshes of the macrotidal Mont Saint Michel bay. They colonised the tidal creeks during each spring tide all along the study conducted in 1997. P. minutus swallowed a least 4% of its body weight. Its diet was dominated by the most abundant resident amphipod of the saltmarshes, Orchestia gammarellus. P. lozanoi ingested less food during their stay in the creek (2.4% of its body weight). O. gammarallus also occurred in its diet, but mysids were the main food items both during flood and ebb. In addition to this trophic segregation, a temporal segregation was observed. In fact, P. minutus stayed longer than P. lozanoi in the saltmarsh ; it colonised creeks first and returned to coastal waters the last. These two predatory and sympatric species had a different trophic behaviour that limited interspecific competition both from the trophic and temporal point of view.