Ecological assessment of the marine ecosystems of Barbuda, West Indies: Using rapid scientific assessment to inform ocean zoning and fisheries management

Morphometric Relationships between Length and Weight of 109 Fish Species in the Caribbean Sea (French West Indies)

In total, 109 fish species (24,996 individuals) were sampled around Guadeloupe and Martinique Islands from October 2021 to September 2022 to estimate the morphometric relationships between total length and weight (Length Weight Relationship: LWR) of each fish species according to potential spatial, temporal and sex differences. Of these species, this is the first time that the LWR was estimated in the Atlantic Ocean for 16 species. There is a significant relationship between length and weight for all tested species. For 83 tested species, the sex effect on the LWR showed significant sexual dimorphism for 24 species. Additionally, a link between the temporal effect and the reproduction period was tested for 68 species, of which 35 presented significant differences relative to the annual quarter of sampling. Finally, the geographical effect (i.e., the difference between samples from around Guadeloupe Island and those from Martinique Island) was significant for 60 species. This island effect was significant for 25 species.

Size and density of upside-down jellyfish, Cassiopea sp., and their impact on benthic fluxes in a Caribbean lagoon

Anthropogenic disturbances may be increasing jellyfish populations globally. Epibenthic jellyfish are ideal organisms for studying this phenomenon due to their sessile lifestyle, broad geographic distribution, and prevalence in near-shore coastal environments. There are few studies, however, that have documented epibenthic jellyfish abundance and measured their impact on ecological processes in tropical ecosystems. In this study, the density and size of the upside-down jellyfish (Cassiopea spp.) were measured in Codrington Lagoon, Barbuda. A sediment core incubation study, with and without Cassiopea, also was performed to determine their impact on benthic oxygen and nutrient fluxes. Densities of Cassiopea were 24-168 m^-2, among the highest reported values in the literature. Under illuminated conditions, Cassiopea increased oxygen production >300% compared to sediment alone, and they changed sediments from net heterotrophy to net autotrophy. Cassiopea increased benthic ammonium uptake, but reduced nitrate uptake, suggesting they can significantly alter nitrogen cycling. Future studies should quantify the abundance of Cassiopea and measure their impacts on ecosystem processes, in order to further determine how anthropogenic-related changes may be altering the function of tropical coastal ecosystems.