EFFECTS OF HURRICANE JOAQUIN ON THE SEDIMENT, BIOTA, AND WATER CHEMISTRY OF INTERIOR PONDS OF SAN SALVADOR, BAHAMAS

Research conducted in March 2016 evaluated Hurricane Joaquin’s impact on marine and hypersaline interior ponds of San Salvador, Bahamas. Sediment cores and water samples were collected from six ponds (Osprey, Oyster, Moon Rock, Pain, Crescent and Reckley Hill) for analysis of water chemistry, sediment sizes and types, and mollusk distributions. While tempestites were predicted, none were identified in the sediment cores from the ponds, attributed to distance and physical barriers to the ocean. Alternatively, autochthonous shell-hash layers identified in almost every pond are attributed to the high energy generated during Joaquin. Sixteen species of gastropods and bivalves and two species of algae were encountered in the cores from ponds. Compared to previously published data for pH, salinity, and nutrients, our data show little change in water chemistry 6 months after the hurricane.

In Oyster Pond, with several conduits to the ocean, abundances of macroalgae and invertebrates on red mangrove (Rhizophora mangle) prop roots and pond outcroppings indicate that the dominant invertebrate species on prop roots is the black mangrove oyster (Isognonzen alatus), while previous studies report burnt mussels (Brachidontes exustus) as dominant. Dominant macroalgae on prop roots include Batophora oerstedii and Acetabularia crenulata and calyculus, while previous studies reported a greater variety of macroalgae more evenly distributed on prop roots. This study provides evidence that the red mangrove prop-root biota is recovering, and is currently less diverse and less abundant than pre-hurricane conditions. On pond outcroppings, many of the same invertebrate and oyster species cited in pre-hurricane studies were noted, but in different quantities. Macroalgae populations shifted after the hurricane due to the absence of previously observed red algae Dasya crovaniana, Polysiphonia subtilissima, and green algae Anadyomene stellata and Pedobesia lamourouxii.

Overall, this study documented thick shell-hash layers in most ponds, and a decrease in algal species richness in Oyster Pond, as well as an alteration of dominant mussel species as compared to pre-hurricane conditions.