Abstract

Background: Parental allocation and reproductive success are often strongly influenced by environmental factors. In

this respect, salinity is a key factor influencing species distributions and community structure in aquatic animals. Nevertheless,

the effects of salinity on reproductive behaviours are not well known. Here, we used the sand goby (Pomatoschistus

minutus), a small fish inhabiting a range of different salinities, to experimentally assess the effects of changes

in salinity on nesting behaviour, a key component of reproduction in sand gobies and many other taxa.

Results: We found that salinity levels influenced some aspects of male nesting behaviour (i.e. nest entrance size) but

not others (i.e. latency to build a nest, choice of nest site, sand on top of nest) and that small and large individuals

were differently affected. In particular, the importance of body size in adjustment of nest entrance depended on the

salinity level.

Conclusion: The results support the prediction that geographically widespread aquatic species, such as sand gobies,

are able to perform well under a range of salinity levels. The phenotype by environment interaction found between

male size and behavioural responses to salinity can, in turn, help to explain the notable variation observed in nestbuilding

(and other) behaviours closely linked to reproduction..