An analysis of arsenic concentrations associated with sargassum influx events in Barbados.

Tropical Atlantic blooms of pelagic Sargassum spp. present major socioeconomic and ecological challenges for Caribbean and West African nations. Valorisation of sargassum provides an opportunity to ameliorate some of the damage to national economies; however, the active uptake of arsenic by pelagic sargassum creates significant barriers to its use. When defining valorisation pathways, it is important to understand arsenic speciation in pelagic sargassum, given the different levels of toxicity associated with different arsenic species. In this study, we assess the temporal variability of total arsenic and inorganic arsenic in pelagic sargassum arriving in Barbados; and test whether arsenic concentrations are linked to oceanic sub-origins. Results indicate that inorganic arsenic, the most toxic form, represents a consistent and substantial percentage of the total arsenic present in pelagic sargassum, and that variability in arsenic concentration does not appear to be driven by sample months, years or oceanic sub-origins/transport pathways.

Seasonal variation in morphotype composition of pelagic Sargassum influx events is linked to oceanic origin.

The recent proliferation of pelagic Sargassum spp. in the Tropical Atlantic causes major ecological and socioeconomic impacts to the wider Caribbean when it washes ashore, with regional fisheries and tourism industries particularly affected. The Caribbean influxes have been tracked to a new bloom region known as the North Equatorial Recirculation Region (NERR) encompassing the area between the South Equatorial Current and the North Equatorial Counter Current and extending from Africa to South America. The vast biomass of Sargassum presents serious problems when it washes ashore but also represents significant commercial opportunities, especially with biofuel and fertilizer. The floating Sargassum mats are themselves diverse ecosystems that vary both in their biodiversity and biochemical attributes. Two major species (Sargassum fluitans and S. natans) have been identified as well as several distinguishable morphotypes of each. Oceanic mixing tends to blend the morphotypes together making it difficult to determine if there are regions of the NERR that favour bloom and growth of the distinct types. In this study, we quantify the species and morphotype composition of Sargassum strandings in Barbados and test if this is related to separate oceanic origins and routes travelled using a backtracking algorithm based on ocean drifter data. We found significant seasonal variation in the relative abundance of three morphotypes and this could be traced to two distinct easterly sub-origins and/or transport pathways; one area around 15° N that travels directly E-W across the Atlantic, and another area generally south of 10° N that takes a more meandering route coming close the coast of South America. These findings contribute towards our understanding of why the Tropical Atlantic bloom is presently occurring as well as towards addressing valorisation constraints surrounding variation in the supply of the three commonly occurring morphotypes.

Parachute science through a regional lens: Marine litter research in the Caribbean Small Island Developing States and the challenge of extra-regional research.

The Wider Caribbean (WC) comprises numerous diverse developing states and territories including Small Island Developing States (SIDS). In particular, the Eastern part of the WC with its 16 SIDS receives a disproportionate amount of marine litter. Addressing this serious and urgent environmental problem requires scientific evidence to support and inform policy formation and decision making. Yet, as this study demonstrates, marine scientific research on the issue of marine litter in the Caribbean SIDS is predominantly undertaken by extra-regional scientists and organisations which might weaken the science-policy transfer to develop suitable and tailor-made solutions. The view point paper highlights issues and the problems associated with parachute science for the Caribbean SIDS before offering a series of potential policy-ready response options to address the identified challenges.