Patterns of behaviour of four shrimp species in a laboratory experiment

This study assessed the behaviour patterns of four shrimp species in a laboratory experiment that was repeated on 8 separate occasions throughout 1978. The experiment was set up in aquariums with sediment and eelgrass densities that reflected field conditions in Western Port Bay, Victoria. There were 1 to 3 replicate aquarium per run of the experiment. The shrimps species used in the experiment were the abundant species in eelgrass beds in Western Port Bay, Macrobrachium.intermedium, Pontophilus intermedius and Hippolyte caradina. Chlorotocella leptorhyncus. All shrimp species were present in each aquarium with a maximum of 4 individuals of each of the larger species (M.intermedium and P.intermedius), to avoid behavioral artifacts due to overcrowding. The behaviour activities and vertical distribution of each species relative to the substrate was assessed by making repeated observations on the instantaneous activity and location of individuals over a 4 day period. Observations were made in the night and day and were classified into 4 categories; inactive, grooming, feeding, or walking/swimming.

P.intermedius was always inactive during the day, and remained partially buried in surface sediments until night when it emerged to move up into the eelgrass. The relative time devoted to feeding was fairly constant between the other 3 species. Levels of inactivity and grooming behaviour were higher during daylight whereas feeding and walking/swimming was more common at night.