Habitat Use, Distribution, and Density of Dwarf Seahorse (Hippocampus zosterae) Populations along the Texas Gulf Coast

The Dwarf Seahorse (Hippocampus zosterae) is one of the smallest species of seahorse and resides in shallow waters throughout the Gulf of Mexico, Atlantic Coast of Florida, and Caribbean. They rely on seagrass beds for feeding, spawning, and refuge, rarely traveling far from the bed in which they were spawned. Information on density, distribution, and habitat associations in Texas are needed to address knowledge gaps and inform future management initiatives. We evaluated seagrass beds along the Texas Coast (from Galveston Bay to the Lower Laguna Madre) to determine what factors correlated with Dwarf Seahorse presence and density. Dwarf Seahorse (n=79) were captured at 30 of 80 (36.3%) sites. They were detected in all sampled bay systems except Galveston Bay. Dwarf Seahorse were found in association with all seagrass species found in Texas. Variables significantly correlated with Dwarf Seahorse presence included average seagrass biomass, turtle grass (Thalassia testudinum) percent cover, and nekton species abundance, evenness, and richness. Variables significantly correlated with Dwarf Seahorse density included number of seagrass species present, the presence of turtle grass, and nekton species evenness, and richness. Nekton species associated with the presence of Dwarf Seahorse included grass shrimp (Palaemonetes spp.), Penaeid shrimp, Code Goby (Gobiosoma robustum), and Rainwater Killifish (Lucania parva). There were an estimated 1,116,356 Dwarf Seahorse in Aransas Bay, 2,769,686 in Upper Laguna Madre, and 7,899,652 in Lower Laguna Madre throughout the sampling time frame. Results from this study will inform continued monitoring, development of a habitat suitability index, and management of this species and their essential habitat.