Biological rhythms in the marine environment: The Norway lobster as a case study

Abstract

The study of biological rhythms in marine invertebrates presents important methodological problems. Species diel movement up and down the three-dimensional environment of the water-column (i.e. mesopelagic migration), along the seabed (i.e. nektobenthic migration) or in and out of the sediment (i.e. endobenthic movements of buriers and burrowers) requires varied sampling procedures depending on the depth, location and time of day. The rhythmic behaviour of the Norway lobster (Nephrops norvegicus) was studied as an example of this, as it affects its commercial catchability at a diel and seasonal level. Animals dig burrows in muddy bottoms and can avoid trawl capture depending on the time of the day. Captures have therefore been used as proxy for activity rhythms of populations at different depths in relation to the day-night cycle. These behavioural features determine that Nephrops is a good model of reference for the study of biological rhythms in marine invertebrates in relation to their ecological context. In this review, we detail recent findings on behavioural and physiological rhythms of single individuals in the laboratory and of populations at different depths.