Regional-scale patterns of habitat preference for the seahorse Hippocampus reidi in the tropical estuarine environment

Abstract

When dealing with species where local information on distribution and habitat preferences is insufficient or lacking (data poor), it is challenging for managers to determine effective measures for conservation. The purpose of this paper was to identify trends in habitat preference for a data-deficient seahorse species, Hippocampus reidi in northeastern Brazil. This is also the first study to use mixed-effect models to compare multiple datasets at a regional level for any seahorse species. Generalized linear mixed-effects models determined that shallow depths, warm temperatures and the number of holdfasts were the most important habitat variables in predicting seahorse presence in tropical estuaries. A log-likelihood ratio *G test found no difference between the proportion of adults and juveniles using various holdfasts, although adults used a greater diversity of holdfasts. The lack of difference in adult and juvenile habitat suggests either that H. reidi may not experience ontogenetic shifts in habitat or that habitat is not determining the distribution patterns of adults and juveniles within estuaries. Alternatively, habitat preference may be coupled with other factors to drive seahorse distribution within estuaries. Due to estuary importance in providing holdfast diversity and other conditions to seahorse use, conservation and management for H. reidi should also consider appropriate protection of estuarine areas, thus safeguarding habitat for both juveniles and adults.