Award: DEB-1350146

This award focused on the changes affecting coral reefs in the US Virgin Islands, and it supported five years of research extending the analysis to 33 years. Coral reefs have long been renowned for their beauty, but in the last few decades they have become the poster child for environmental degradation. While the study reefs along the shore of St. John are protected within the VI National Park, they have not been immune to declines in coral abundance. These declines contribute to the ?coral reef crisis?, and it is studies like the one supported here that provide the data necessary to inform the discussion of this critical phenomenon. Long-term studies are the only means to record the losses of coral that are taking place, to forecast the form in which coral reefs will persist, and to support conservation promoting effective resource management.

When this project began, its intellectual merits focused on ensuring the longevity of the monitoring by extending measurements of coral abundance to 33 years. This task generated the pattern-oriented aspect of the study, and has revealed how the losses of coral have stabilized at ~ 4% cover close to the shore, and ~ 26% in deeper water. Throughout the study, baby corals have settled through the region, but they generally fail to endure the ?settlement gauntlet? and do not become adults. The stringency of this ?gauntlet? has been intensified by the arrival of a new encrusting alga (abbreviated to ?PAC?) that is dominating hard surfaces in shallow water and is beginning to invade deeper regions. In the middle of the award (September 2017), these reefs were impacted by the two biggest hurricanes to occur in the region within human memory, and St. John was devastated by strong winds and waves. Underwater damage attributed to these storms was modest, however, because the reefs were so degraded when the storm arrived. After > 30 years, these reefs have attained resilience through adversity, which underscores the highly degraded state of modern ecosystems, as well as the limited ability of historic studies to inform understanding of present-day disturbances. One striking example of the changing community structure of these reefs is the rising dominance of soft corals that currently provide much of the three-dimensional structure of the reef. Soft corals are emerging as ecological ?placeholder? that are likely to function as the ?new normal? for years to come.

Having ensured the longevity of the time series, the research focused on process-oriented analyses to explore mechanisms driving the changes in coral abundance. This effort focused on the population biology of corals to quantify the arrival of baby corals (i.e., ?recruitment?), and to forecast population sizes in the future. The population analyses reveal how coral colonies have declined in size though partial death, but in this depleted state, forecasts reveal that the populations are likely to persist over the next few decades. Accompanying these changes, coral recruitment has remained relatively high, yet most recruits fail to survive to an adult size. Variation in temperature is associated with changes in coral recruitment, with recruitment elevated under high and low seawater temperature. One reason why coral recruits do not contribute to adult size classes is that they appear to be unable to ?predict? future conditions, so that corals that growing rapidly under present conditions are unable to continue rapid growth in future years. This outcome could arise from the high speed with which environmental conditions are changing, or because the growth of corals has been depressed to such a large extent that they have lost their ability to predict future performance.

In pursuit of the intellectual merits of this award, broader impacts were achieved through a program engaging students in science, and by providing opportunities for research to stakeholders at multiple stages of career development. Undergraduate and graduate students have been embedded in field expeditions to St. John, where they have learned about the biology of the Caribbean, completed research, and integrated with eco-camps providing instruction to children from Caribbean nations. Together, these opportunities provide unique exposure to inspiring and diverse biological systems that have served as the crucible of scientific creativity for centuries. These experiences facilitate the training of a globally aware, and empirically trained, STEM workforce. This goal has been further advanced by partnerships with schools in California to support marine biology clubs, provide opportunities for research using photographs of Caribbean reefs, and to staff field expeditions in California and in St. John. Finally, the data arising from this project have been archived and made freely available to the public and professional community as a resource to better understand the state of coral reef resources in US waters. The images supporting these analyses are archived on-line to provide an international resource to further the analysis and conservation of coral reefs.

Last Modified: 05/06/2020
Modified by: Peter J Edmunds