Are nest sites a limiting resource for speleophilic nesting fishes in sand dominated temporarily open/closed estuaries?
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Southern African temporarily open/closed estuaries are often characterized by sand dominated mouth regions, a feature in contrast to many permanently open estuaries of the region which regularly have substantial rocky areas. Here we explore how habitat characteristics may reduce nesting opportunities and potentially explain population trends for a common estuarine fish species, the speckled sand goby Psammogobius knysnaensis, in many temporarily open/closed estuaries in South Africa. The present study is the first to document that P. knysnaensis is a speleophilic nester, utilizing the underside of rocks and other hard substrata for egg attachment. Furthermore, our results suggest that ideal nesting habitat for the speckled sand goby is potentially a limiting resource in sand-dominated temporarily open/closed estuaries. We postulate that this is a factor contributing to the relatively low numbers of adult P. knysnaensis found in sandy temporarily open/closed estuaries of the region, although the role of marine connectivity, food availability, predation pressure and other environmental factors in this regard still remain largely unassessed.
KeywordsAutecology Eggs Gobiidae Psammogobius knysnaensis Reproduction
This work was financially supported by the National Research Foundation of South Africa (NRF, UID: 88746). Tatenda Dalu was funded by a Claude Leon Post-Doctoral Research Fellowship.
Compliance with ethical standards
Conflict of interest
RJ Wasserman declares that he has no conflict of interest. AK Whitfield declares that he has no conflict of interest. RJ Welch declares that she has no conflict of interest. T Dalu declares that he has no conflict of interest.
All applicable institutional guidelines for the care of animals were followed. This article does not contain any studies with human participants performed by any of the authors.
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