Habitat use by seahorses and pipefishes (family Syngnathidae) in Biscayne National Park, a marine protected area in southeastern Florida, USA.

Seahorses and their relatives, the pipefishes, (family Syngnathidae) are a group of charismatic marine fishes found in coastal habitats including estuaries, mangroves, seagrasses and coral reefs. Knowledge of habitat use by species of conservation concern is important when evaluating the relative contribution of a marine protected area to recovery efforts.

This study presents the results of underwater visual surveys of broadly-defined habitats (continuous Submerged Rooted Vegetation (SRV), discontinuous SRV, and reefs) conducted in Biscayne National Park (BNP), a 720 kmĀ² marine protected area in Florida, USA. Syngnathids were more likely to be found inside the sheltered waters of Biscayne Bay at sites characterized by fine sediment, reduced horizonal visibility, 30-70% seagrass cover (predominantly Thalassia testudinum) and lower % coverage of reef-associated benthic invertebrates (sponges, corals, gorgonians) and turf algae.

The most abundant syngnathids in BNP were the Dwarf Seahorse (Hippocampus zosterae), the Gulf Pipefish (Syngnathus scovelli), and the Dusky Pipefish (S. floridae). Large seahorses (Hippocampus erectus and H. reidi) were poorly represented in my surveys.

Syngnathid species assemblage varied by major habitat type, however only Syngnathus floridae was significantly more likely to be found in continuous SRV habitats. Discriminant function analysis (DFA) revealed that relative to habitats occupied by H. zosterae and S. scovelli, those occupied by S. floridae had higher % coverage Thalassia, and higher salinity.

The analysis further revealed that habitats occupied by H. zosterae are associated with relatively deeper sediments, lower % coverage of sponges, and higher % cover drift algae compared to habitats used by S. scovelli. Sediment type emerged as the most important predictor of occurrence for H. zosterae, S. scovelli, and syngnathids generally and is an important parameter to consider for conservation and management of syngnathid habitat.

It is likely that the sheltered waters of Biscayne Bay provide important habitat for syngnathids within BNP, but also that Biscayne Bay is exposed to greater environmental stressors resulting from its proximity to the mainland and the effects commercial bait-shrimp trawling. Implementation of the no-trawl-zone proposed in the 2014 Fisheries Management Plan for Biscayne National Park and improving water quality would benefit syngnathid habitat.

Stump, E. 2018. Habitat use by seahorses and pipefishes (family Syngnathidae) in Biscayne National Park, a marine protected area in southeastern Florida, USA. Master dissertation. The University of British Columbia. http://hdl.handle.net/2429/67731