Inland blue holes of The Bahamas – chemistry and biology in a unique aquatic environment

While lake systems in temperate regions have been extensively studied, tropical and subtropical systems have received less attention. Here, we describe the water chemistry and biota of ten inland blue holes on Andros Island, The Bahamas, representative of the morphological, abiotic, and biotic variation among Androsian inland blue holes. The majority of the studied blue holes were vertically stratified with oxic freshwater overlying anoxic saline groundwater of marine origin. Water chemistry (e.g.total phosphorus and nitrogen) in shallow waters was similar among blue holes, while turbidity and water color varied. Presence of hydrogen sulfide and reduced iron in and below the halocline indicate reducing conditions in all stratified blue holes. The biota above the halocline was also similar among blue holes with a few taxa dominating the phytoplankton community, and the zooplankton community consisting of copepods and rotifers. The Bahamas mosquitofish (Gambusia hubbsi) was present in all investigated blue holes, often accompanied by other small planktivorous fish, while the piscivorous bigmouth sleeper (Gobiomorus dormitor) was only present in some of the blue holes. Our field study reinforces that inland blue holes are highly interesting for biogeochemical research, and provide naturally replicated systems for evolu- tionary studies.

Registro de larvas de Sebekia sp. (Pentastomida: Sebekidae) en peces de la cuenca media del río Usumacinta, Tabasco, México

Peces de importancia comercial en Tabasco, México, están siendo infestados de manera natural con parásitos de pentastómidos. En la presente investigación se dan a conocer la morfología, los índices ecológicos de infección de la larva en tres especies de valor comercial. Los peces bajo estudio son mojarras de interés alimenticio como Parachromis managuensis, Petenia splendida y Gobiomorus dormitor. Se registró un total de 30 larvas de pentastómidos. La mayor prevalencia registrada en estos fue en G. dormitor de 30% y 35%, durante los años 2005 y 2015, respectivamente. La prevalencia por larvas de pentastómido ha incrementado en las especies estudiadas. Por tanto, se recomienda evitar el consumo de ejemplares crudos en diferentes platillos, y se propone al sector salud tomar las medidas precautorias ante la sociedad para evitar infección a humanos por esta larva.

Fishes from Lachuá Lake, Upper Usumacinta Basin, Guatemala

Guatemala’s Maya Lowlands constitute one of the most biodiverse regions in Mesoamerica and include 35% of the total number of continental fish species estimated for the nation. From May 2000 through February 2001, we conducted the first long-term ichthyological survey of Lachuá Lake, a 4 km2, 195 m deep, karstic sinkhole located in the middle of Guatemala’s Laguna Lachuá National Park (LLNP), southern Maya Lowlands. Thirty-six native fish species were identified and Gobiomorus dormitor Lacepède, 1800 was collected for the first time in northern Guatemala. Greater number of species occurred in the rocky shore of the lake’s littoral zone, especially around the mouths of Lachuá’s tributary and effluent rivers, and close to the visitor center of LLNP. A hierarchical cluster analysis for classifying ichthyogeographically regional fish assemblages placed Lachuá Lake in the upper Usumacinta River drainage basin shared by Guatemala and Mexico, stressing the need for regional conservation and management strategies.