CORAL REEF RESEARCH
The US Virgin Islands has a long history of local stress to coral reefs, including the escalating use of land and sea resources with little planning and regulation. Concurrently, rapid land development has increased soil erosion and subsequent sedimentation in the marine environment to levels greatly above normal, increasing the susceptibility of coral colonies to bleaching, disease and mortality.
Recently, external drivers are becoming more important and are threatening to overwhelm much of the intrinsic capacity for resilience in these systems. Significantly, the invasive Indo-Pacific lionfish (Pterois volitans), is now fully established throughout most of the greater Caribbean region. The rapid increase in lionfish populations and their voracious diet of juvenile reef fish has the potential to negatively impact small island economies through the decline of commercial fisheries and loss of ecologically important species.
The coral reef research program studies the interactions between physical, biological and human factors to understand coral reef composition and its ecosystems from shallow waters to deeper offshore reefs. This research area is divided into three sub-areas: Dynamics, Disease, and Demographics.
Global warming and the reduction of plant-eating fish are emerging as factors central to the degradation of coral reefs.
VI-EPSCoR funded research is investigating the effect of increasing ocean temperatures on coral reef systems both on- and offshore. Coral reefs may experience temperature differences as great as 3˚C, sometimes in the course of one day. What impact that has on the health and resilience of the reefs is a focal point of investigation.
Herbivory is another important dynamic process within coral reef ecosystems. The loss of major plant grazers, such as the parrotfish, to fishing and disease has allowed an increase of algal growth among corals. We are testing the general hypothesis that diversity in herbivore reef communities helps control the growth. Anticipated results will be to understand how the coral reef community maintains its core processes despite the indicated stresses and depending on their location (nearshore, offshore, shallow-deep and north-south).
Coral disease outbreaks on Caribbean coral reefs have caused some of the worst regional declines of living coral in recent times and have had significant effects on the diversity and structure of reef systems. The susceptibility of corals to disease and bleaching may be linked to and magnified by the exposure to terrestrial pollutants and sediments. Understanding how these factors, and others, affect the incidence and transmissibility of diseases and ultimately coral demographics is key to determining long-term trajectories of coral reef communities. Anticipated results will be to define the greatest stressors and thereby understand which factors most significantly promote the spread and impact of diseases in the Caribbean.
This research focuses on three key elements of coral reef ecosystems that affect the demographic rates and distribution of important species groups, including reef fishes, marine algae, and corals.
(A) We are testing the general hypothesis that increasing sea temperatures will disrupt the temporal coupling of sensitive biological processes like reproduction.
(B) We are testing the general hypothesis that changes in fish demographics have direct and indirect effects on coral reef community structure, coral demographics and reef resilience.
(C) We are testing the influences of marine algal growth and nutrient supplies on coral communities.