Environmental Variables Influencing the Distribution of Penaeus Shrimp (Decapoda: Dendrobranchiata: Penaeidae) in a Subtropical Estuary of the Gulf of Mexico

The habitat characteristics preferred by Penaeus shrimp inhabiting positive (freshwater-dominated) estuaries in North America have been scarcely investigated. Identifying the main environmental factors within the estuary that affect shrimp abundance is relevant to understanding habitat utilization within this particular nursery habitat. This study aimed to evaluate the distribution of penaeid shrimp species along the Soto La Marina River estuary (Northeastern Mexico), analyzing the influence of abiotic factors (water temperature, salinity, and dissolved oxygen) and submerged aquatic vegetation biomass on shrimp populations. A total of 1069 shrimp belonging to four penaeid species (Penaeus aztecus, P. duorarum, P. brasiliensis, and P. setiferus) were collected. Except for P. setiferus, the highest shrimp abundance was near the mouth of the estuary, where the highest salinity and seagrass biomass (Halodule wrightii) were recorded. Salinity and seagrass biomass were the main factors influencing penaeids’ spatial preferences along the estuary, showing significant positive relationships with shrimp abundance in most of the cases examined. Penaeus setiferus was the only species exhibiting peak abundance in an estuarine area devoid of aquatic vegetation (without seagrass or macroalgae) and with a significantly lower salinity level (ca. 22 ppt) than the levels recorded near the river mouth (ca. 28–32 ppt). Differences in osmotic capacity between the species, the protective function of seagrasses against currents, and their role as feeding and refuge habitats could explain the observed spatial distribution in the estuary.