With the support of a near US$1 million grant from the National Science Foundation, researchers are in Trinidad to collect samples of the blue sea crab found in the Gulf of Paria for further analysis and testing. This forms part of on-going research to determine how variation in life history and connectivity drive pathogen-host dynamics and genetic structure in a trans-hemispheric pathosystem.
While the geographic sampling area spans across the greater Atlantic from Maine in northern USA to Argentina in the south; the findings will be of interest to the smallest economic participants in the local fishery as well as the national population of Trinidad and Tobago.
Dr Donald Behringer, marine and disease ecologist, associate professor and project lead from the University of Florida, explained that marine invertebrates display a staggering variety of life cycle characteristics, many of which vary across space and time. These include different strategies for dispersing offspring such as long pelagic larval stages, or strategies for surviving unfavourable environmental conditions such as winter dormancy.
While we understand much about these life cycle characteristics for important fishery species such as the blue crab (Callinectes sapidus), we understand little about how variations in these characteristics interact with large-scale movement of individuals in the oceans to shape connections between populations.
Similarly, we are aware of the emergence and impact of diseases on marine organisms such as crustaceans, corals, and echinoderms, but are only beginning to understand how they spread between distant host populations.
However, recent advancements in oceanographic modelling, genetic techniques, and animal tracking technologies have greatly increased our ability to measure and model population connectivity in the ocean.
The blue crab is an ecologically important benthic crustacean with a remarkable range that spans the Atlantic coast of both North and South America. In its temperate range, the species exhibits an annual cycle of summer activity and winter dormancy with a truncated growth and reproduction period at the northern and southern ends of its range. In the center of its range, activity and reproduction is year-round.
However, across all sites studied, C. sapidus is infected by the same pathogenic virus (CsRV1). This project will use acoustic tracking and laboratory studies to reveal how crab life history and pathogen dynamics interact and adapt at the extremes of their range.
The project will produce genomic data to define population structure for the crab and virus and test for patterns of gene flow driven by expected oceanographic barriers, adult movement, larval connectivity, and host life history. Movement and genomic data will be integrated with oceanographic and benthic population models that cover the full trans-hemispheric range of the crab and virus.
The convergence of these techniques operating on different spatiotemporal scales will give us a novel and multi-dimensional understanding of how life history, oceanography, and latitude interact with disease to dictate the ecology and genetic structure of the pathogen-host system.
In Trinidad and Tobago the blue sea crab has certain socioeconomic value and its heavily depleted stocks and landings remains a delicacy similar to other jurisdictions. While there has been significant advocacy focused on the integrity and sustainability the Gulf of Paria and its inherent fishery for many years; the outstanding issues remain largely unaddressed.
The focal points have been the damage inflicted by energy and industrial interests, unsustainable fishing practices, and general environmental interactions from climate change through flooding and effluent on the fishery especially juveniles, breeding grounds and vulnerable species. In this instance, further pressure on food and nutrition security as well as livelihoods is possible through viruses and genetic changes.
Any move towards sustainable development requires a strategy based on instilling resilience in economic, environmental, social and political systems but more so by building the human assets needed for sustained development. International cooperation can support small island developing states, including Trinidad and Tobago, to build resilience and encourage stakeholder participation in a number of areas.
We are of the shared view that more must be done within the fisheries sector and towards all actions, voluntarily or involuntarily, that lead to its detriment. This includes, but not limited to, fishing techniques and regulations, measures to protect habitat and breeding grounds, enforcement, adopting proper equipment and procedures at sea and at landing sites, and related public awareness and education concerning the sector.
Ultimately, Trinidad and Tobago would benefit from the knowledge generated in this project; resource managers who need to manage fisheries, including the artisanal soft shell crab industry, sustainably. Simple best practices to avoid disease mortality and curtail spread of the virus are being developed and could be communicated to fisherfolk through direct collaboration and public workshops.
The project also includes formal and informal educational programs integrated with the research program. We, as a people, must commit to supporting activities which put value into the hands of the people who need them the most but also those that claw at development.
The team expressed their gratitude for the support and assistance provided by the Claxton Bay Fishing Association, Felicity Charlieville Fishing Association, Otaheite Fishing Association, Fisheries Division and the Department of Agricultural Economics and Extension, University of the West Indies. They leave for Grenada tomorrow.