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

Habitat characteristics preferred by Penaeus shrimp inhabiting positive estuaries (freshwater-dominated) in North America have been little 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 and submerged aquatic vegetation biomass on shrimp populations. A total of 1,069 shrimp belonging to four penaeid species (Penaeus aztecus, P. duorarum, P. brasiliensis, and P. setiferus) were collected. For most species, except P. setiferus, the highest shrimp abundance was noted 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 penaeid spatial preferences along the estuary, showing significant positive relationships with shrimp abundance in most 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 significantly lower salinities (ca. 22 ppt) than those recorded near the river mouth (ca. 28–32 ppt). Differences in osmotic capacity among species, the protective function of seagrasses against currents, and their role as feeding and refuge habitats could explain the observed spatial distribution along the estuary.