Professor Dale Webber

Publication/source: Frontiers in Environmental Science 14, 1950286, 2026

Snippet: Mangroves are among the most carbon-rich tropical forests, with much of their carbon stock located in underlying sediments. They play a vital role in climate mitigation and adaptation by offsetting carbon dioxide emissions linked to global warming. Despite their importance, blue carbon ecosystems remain poorly represented in climate policy across the Caribbean, with Jamaica and Belize being the only Caribbean countries to incorporate blue carbon stock values into their Nationally Determined Contributions (NDCs). Limited standardized information on mangrove carbon stocks across representative forest types in the region, further constrains the development of national baselines and their integration into climate policies. We conducted comprehensive mangrove carbon assessments across seven sites within four forest ecotypes: riverine, fringing, cay and lake to establish a national carbon baseline. The national mean total ecosystem carbon stock was determined to be 387.8 ± 18.6 Mg C ha-1. Recent island-wide mapping of mangrove forests determined Jamaica’s total mangrove extent to be 11,978 ha. Using these values, a total national carbon stock of 4.7 ± 0.2 Tg C was determined for Jamaican mangrove forests, with 3.5 Tg C stored as sediment stocks, 1.1 Tg C as above and below-ground tree biomass and 0.08 Tg C as standing dead tree biomass. Results indicate that forests within freshwater systems had the greatest carbon stored as living biomass (79.5 ± 15.7 Mg C ha-1), while forests on small mangrove cays, had the highest sediment carbon (344.6 ± 13.1 Mg C ha-1) despite influences from tidal flows. The random forest regression predictor identified sediment pH as important predictors across all carbon components, while forest type was important for standing dead and sediment carbon. Water salinity was a strong predictor of standing dead carbon and a weak and negative predictor for biomass carbon. This study provides valuable insight on the variability of mangrove carbon in different forest types potentially supporting sustainable management and conservation strategies necessary to inform policy. It represents the most extensive mangrove carbon assessment done in Jamaica with results informing the 2025 update of the island’s NDCs, a commitment under the Paris Agreement.

Publication/source: OOS2025, 2025

Snippet: Microplastic pollution is a growing environmental concern in the Caribbean, threatening both marine biodiversity and human health. In response, regional efforts have been intensifying to monitor and mitigate the impact of microplastics on the region's ecosystems. A significant initiative in this regard is the International Atomic Energy Agency (IAEA) NUTEC Plastics project, which aims to enhance the capacity of Caribbean countries to monitor microplastics and harmonize protocols for data collection and analysis. The NUTEC Plastics project, launched in 2020, is part of a broader international effort to combat plastic pollution using nuclear technology and isotopic techniques. By incorporating innovative nuclear and analytical techniques, the project enables more precise monitoring of microplastic sources, pathways, and accumulation in marine ecosystems. Prior to the initiative, a lack of standardized methodologies made it difficult to compare data across countries, hampering efforts to assess the true extent of microplastic contamination. Progress in the harmonization of protocols has been notable. Workshops, training programs, and collaborative research efforts have been organized to build capacity and foster knowledge sharing among Caribbean countries. At a recent Technical Cooperation Regional Meeting for the Harmonization of Operational Protocols for the Collection, Identification and Counting of Microplastics in Beach Sands and Seawater in Monaco, from 14 to 18 October 2024, nine countries (Antigua & Barbuda, Bahamas, Belize, Dominica, Jamaica, St. Kitts & Nevis, St. Lucia, St. Vincent & the Grenadines and Trinidad & Tobago) gathered to discuss and standardize the methodologies for determining the abundance of MPs in beach sand and marine waters with a size range from 300 μm to 5 mm. Training in sample collection, field protocols and laboratory processing exercises was conducted for beach sands and coastal waters. As a result, several nations now have improved technical expertise in microplastics sampling, laboratory analysis, and data interpretation. Additionally, the IAEA has facilitated the procurement of standardized microplastics detection kit for each country and the creation of a regional database for microplastics, which will allow for real-time data sharing and informed decision-making in environmental management. Continued training is planned at the Centre for Marine Sciences of the University of the West Indies Mona Campus for July 2025 where increased numbers of countries and participants are anticipated. Overall, the IAEA NUTEC Plastics project has played a crucial role in strengthening the Caribbean's ability to monitor microplastic pollution. Through the harmonization of monitoring protocols and capacity-building initiatives, the project is enhancing regional cooperation and enabling a more coordinated response to the growing challenge of plastic pollution in the Caribbean.

Publication/source: Phycology 5 (3), 44, 2025

Snippet: Pelagic Sargassum impacts the Caribbean and West Africa since 2011, disrupting economies and bringing major environmental, social, and health concerns. Avenues explored to valorise this biomass include the production of liquid biofertilisers and biostimulants. There has been less emphasis on the production of compost and mulch, and on their impact on plant growth. Therefore, the effects of compost and mulch prepared from rinsed and unrinsed Sargassum on corn, tomato, and pepper were investigated in this study. The elemental composition of soil, compost, mulch, and plant samples was also assessed to investigate the potential transfer of metals and metalloids from the compost and mulch to different parts of the plants (roots, leaves, and fruits). Sargassum-derived composts exhibited less effects on seed germination compared to mulch. Significant differences (p ≤ 0.05) between treatments were observed for seedling growth parameters (height, shoot diameter, and number of leaves). Post-harvest parameters were mixed with the leaf area index and the root-to-shoot ratios varied significantly between treatments but not moisture content. Variations in elemental concentrations were observed between the different parts of the plants and evaluated against established nutritional recommendations and toxicity thresholds. This study provides foundational insights for optimising pelagic Sargassum-based compost and mulch preparation to support plant growth.

Publication/source: Proceedings of the National Academy of Sciences 121 (23), e2312173121, 2024

Snippet: The year 2021 marked a decade of holopelagic sargassum (morphotypes Sargassum natans I and VIII, and Sargassum fluitans III) stranding on the Caribbean and West African coasts. Beaching of millions of tons of sargassum negatively impacts coastal ecosystems, economies, and human health. Additionally, the La Soufrière volcano erupted in St. Vincent in April 2021, at the start of the sargassum season. We investigated potential monthly variations in morphotype abundance and biomass composition of sargassum harvested in Jamaica and assessed the influence of processing methods (shade-drying vs. frozen samples) and of volcanic ash exposure on biochemical and elemental components. S. fluitans III was the most abundant morphotype across the year. Limited monthly variations were observed for key brown algal components (phlorotannins, fucoxanthin, and alginate). Shade-drying did not significantly alter the contents of proteins but affected levels of phlorotannins, fucoxanthin, mannitol, and alginate. Simulation of sargassum and volcanic ash drift combined with age statistics suggested that sargassum potentially shared the surface layer with ash for ~50 d, approximately 100 d before stranding in Jamaica. Integrated elemental analysis of volcanic ash, ambient seawater, and sargassum biomass showed that algae harvested from August had accumulated P, Al, Fe, Mn, Zn, and Ni, probably from the ash, and contained less As. This ash fingerprint confirmed the geographical origin and drift timescale of sargassum. Since environmental conditions and processing methods influence biomass composition, efforts should continue to improve understanding, forecasting, monitoring, and valorizing sargassum, particularly as strandings of sargassum show no sign of abating.

Publication/source: Proceedings of the National Academy of Sciences 121 (34), e2412718121, 2024

Snippet: Gobert et al.(1) present new data on three elements, Fe, Al, and Mn, in sargassum harvested in June 2021 near the French Caribbean Islands Guadeloupe and Martinique (FCIs). They also analyzed the content of these elements in sargassum incubated for 21 d in the coastal area of Baie du Robert (Martinique). Using this information, they challenged our suggestion that exposure of sargassum to ash after La Soufrière volcanic eruption (April 2021) may have contributed to increasing the content of these three metals in biomass harvested in Jamaica from August 2021 (2). Previously, Gobert et al.(3) suggested that coastal waters received terrigenous inputs, including Al, Fe, and Mn, increasing the content of these elements in sargassum harvested in coastal areas. Considering the high Fe, Al, and Mn content in La Soufrière volcanic ash, together with the potential exposure of sargassum to ash for 50 d, it made sense to us to suggest that this unusual condition could alter the elemental composition of sargassum biomass arriving in late summer in Jamaica (2). Compared to Jamaica, FCIs are much closer to the sargassum potentially affected by volcanic ash, so sargassum arriving offshore of these islands will have had less time (2 mo, by June) to assimilate elements than the sargassum reaching Jamaica (after 4 mo). Additionally, there is still uncertainty in how long, and along which pathways, the sargassum was sharing ash-enriched surface water (2). A further caveat with the June samples is that the potentially ash-affected sargassum arrived more quickly in FCIs than Gobert et al.(1) supposed, probably in May. Downstream at Jamaica, months later, dispersal along the transport pathway and during extended time may have more clearly impacted sargassum elemental composition. Moreover, much of the sargassum arriving in FCIs, the northern sector of the Lesser Antilles, is likely to come from outside the area downwind of La Soufrière (4), so a sampled mix of sargassum may be largely unaffected by ash deposition. Particle tracking data presented in Machado et al.(2) suggested that in 2021 a high proportion of sargassum reached Jamaica via the western boundary current after potential exposure to volcanic ash. Finally, considering the trajectory of sargassum reaching Jamaica, it is unlikely this biomass spent up to 21 d confined and growing in a coastal zone environment similar to the Baie du Robert (1). At the Jamaican collection site, sargassum beaches “directly” on each tide after short residence time in coastal waters, with therefore little opportunity to accumulate terrigenous metals. To conclude, we suggest that more coordinated and interdisciplinary research is needed to investigate the biology and the ecology of pelagic sargassum during its advection. This could involve GPS tracking of algae rafts during a full season of sargassum to inform regular sampling and then investigation of morphotype abundance, fauna, and microbiota associated with the rafts and of (bio) chemical composition of the algae. Integrating such information will advance the understanding and prediction of new pelagic sargassum ecosystems under changing environmental conditions. 1. T. Gobert et al., La Soufrière volcanic eruption in 2021 was not responsible for the high Fe, Al or Mn concentrations found in stranded Sargassum spp. Proc. Natl. Acad. Sci. USA. 121, e2411350121 (2024). 2. CB Machado et al., Changes in holopelagic Sargassum spp. biomass composition across an unusual year. Proc. Natl. Acad. Sci. USA 121, e2312173121 (2024). 3. T. Gobert et al., Trace metal content from holopelagic Sargassum spp. sampled in the tropical North Atlantic Ocean: Emphasis …