t~, William F. ~e r r n k i n d~, Michael J. childress3, Rodney ~e r t e l s e n~, William sharp2, Thomas ~a t t h e w s~, J e n n i f e r M. Field4, Harold G. ~a r s h a l l ' is experiencing an unprecedented series of ecological disturbances. In 1991, following reports of other ecosystem perturbations, we observed widespread and persistent blooms of cyanobacteria that coincided with the decimation of sponge communities over hundreds of square kilometers. Juvenile Caribbean spiny lobsters Panulirus argus, among other animals, rely on sponges for shelter; the impact of sponge loss on the abundance of lobsters and their use of shelter, in particular, has been dramatic. The loss of sponges on 27 experimental sites in hard bottom habitat in central Florida Bay resulted in the redistribution of juvenile lobsters among the remaining shelters, an influx of lobsters into sites where artificial shelters were present, and a decline in lobster abundances on sites without artificial shelters. Diver surveys of sponge damage at additional sites in central Florida Bay confirmed that the sponge die-off was widespread and its occurrence coincided with areas that had been exposed to the cyanobacteria bloom. This cascade of disturbances has dramatically altered the community structure of affected hard bottom areas and demonstrates the coupled dynamics of this shallow marine ecosystem.

No abstract

Incorporating ecological processes into restoration planning is increasingly recognized as a fundamental component of successful restoration strategies. We outline a scientific framework to advance the emerging field of coral restoration. We advocate for harnessing ecological processes that drive community dynamics on coral reefs in a way that facilitates the establishment and growth of restored corals. Drawing on decades of coral reef ecology research and lessons learned from the restoration of other ecosystems, we posit that restoration practitioners can control factors such as the density, diversity, and identity of transplanted corals; site selection; and transplant design to restore positive feedback processes – or to disrupt negative feedback processes – in order to improve restoration success. Ultimately, we argue that coral restoration should explicitly incorporate key natural processes to exploit dynamic ecological forces and drive recovery of coral reef ecosystems.

Unusually dense aggregations of the sea urchin Lytechinus variegatus overgrazed at least 0.81 kmz of seagrass habitat in Outer Florida Bay (USA) between August 1997 and I\,Iay 1998. Initially, sea-urchin densities were as high as 364 sea urchins m-', but they steadily declined to within a range of 20 to 50 sea urchins m-2 by December 1998. Prior to this event, sea-urchin densities were <1 sea urchin m-2 in this area of Outer Florida Bay. Seagrasses in Outer Florida Bay consist primarily of manatee grass Syringodium filiforme. of which 82% or 390 g dry weight rn-2 of total seagrass biornass and >95% of the short-shoot apical menstems were removed by sea-urchin grazing in our study area. Such extensive loss may severely limit recovery of this seagrass comrnunity by vegetative reproduction. Effects of the removal of seagrass biomass have already resulted in the depletion of epifaunal-infaunal mollusk assemblages and resuspension of fine-grained (<64 pm) surface sediments-which have caused significant changes in cornrnunity structure and in the physical properties of the Sediments. These changes, coupled with the loss of essential fishery habitat, reductions in primary and secondary production, and degradation of water quality, may lead to additional, longer-term, indirect effects that may extend beyond the boundaries of the grazed areas and into adjacent coastal ecosystems.

Along the Florida reef tract, stony-coral-tissue-loss disease (SCTLD) has caused extensive mortality of more than 20 scleractinian coral species. The pathogen is unknown, but its epizoology indicates that the disease, facilitated by water currents, has progressed linearly along the tract, affecting reefs at the scale of hundreds of kilometers. To inform ongoing disease mitigation efforts, we examined the small-scale spatial and temporal epidemiology of SCTLD. We established a series of sites in the middle Florida Keys at offshore and inshore locations that had not yet shown signs of SCTLD. We then conducted high-frequency monitoring from February 2018 through September 2019 and documented the onset of SCTLD and its progression through the sites. SCTLD was first observed at one site during early February 2018 and by early March 2018 all sites showed signs of the disease. A dynamic multistate model suggested that disease transmission was independent of coral density and found little evidence of a positive association between a colony showing signs of SCTLD and the condition or distance to its neighboring colonies. The model did, however, indicate that the probability of a colony showing signs of SCTLD increased with increasing colony surface area. These results are consistent with the water-borne transmission of a pathogen that progressed rapidly through the survey area. However, by the end of our survey the progression of SCTLD had slowed, particularly at inshore sites. Many affected colonies no longer exhibited progressive tissue mortality typical of the disease, suggesting the existence of differentially resilient colonies or coral communities, meriting their use for future coral rescue and propagation and disease research. These results are useful for refining ongoing SCTLD mitigation strategies, particularly by determining when disease rates are sufficiently low for direct intervention efforts designed to arrest disease progression on individual coral colonies will be most effective.