Occasional utilization of crustacean burrows by the estuarine goby Mugilogobius abei

Abstract

Many species of gobies live in close association with various burrowing crustaceans. Mugilogobius abei is a common species distributed in a variety of estuarine environments from tidal pools in mudflats to tidal channels, even in polluted areas. This goby is usually found resting under pebbles, but gobies have been reported to use the burrows of upogebiid shrimp and brachyuran crabs as a shelter. This study aimed to describe the crustacean burrow use pattern of M. abei through both aquarium and field observations. In aquaria, we observed the behavior of the goby in the presence of burrowing mud shrimp Upogebia yokoyai or the crab Macrophthalmus banzai. A total of 19 out of 20 experimental individuals used shrimp burrows in the presence of the shrimp when the mud surface was covered with water. The goby entered and exited the burrows with bout durations of several seconds to over 10 s, and the goby spent 1–3% of the observation period in shrimp burrows. The goby used artificial crab burrows in much the same way in aquaria. In the field, we compared the shelters used by M. abei at two study sites where the availability of surface structures was different. The results showed that M. abei used crustacean burrows more often as a shelter in the habitat in which fewer surface structures were available. In summary, crustacean burrows are one of the items that can be used as shelters by goby, and their utilization patterns may vary depending on the characteristics of their habitat.