TRopical Oil Pollution Investigations in Coastal Systems [TROPICS]: A synopsis of impacts and recovery.

The TRopical Oil Pollution Investigations in Coastal Systems (TROPICS) experiment, conducted on the Caribbean coast of Panama, has become one of the most comprehensive field experiments examining the long-term impacts of oil and dispersed oil exposures in nearshore tropical marine environments. From the initial experiment through more than three decades of study and data collection visits, the intertidal and subtidal communities have exhibited significantly different impact and recovery regimes, depending on whether the sites were exposed to crude oil only or crude oil treated with a chemical dispersant. This review provides a synopsis of the original experiment and a cumulative summary of the results and observations, illustrating the environmental and ecosystem trade-offs of chemical dispersant use in mangrove, seagrass, and coral reef environments.

Acute and subacute toxicity of the polycyclic aromatic hydrocarbon 1-methylnaphthalene to the shallow-water coral Porites divaricata: Application of a novel exposure protocol.

Previous research evaluating hydrocarbon toxicity to corals and coral reefs has generally focused on community-level effects, and results often are not comparable between studies because of variability in hydrocarbon exposure characterization and evaluation of coral health and mortality during exposure. Toxicity of the polycyclic aromatic hydrocarbon 1-methylnaphthalene to the coral Porites divaricata was assessed in a constant exposure toxicity test utilizing a novel toxicity testing protocol uniquely applicable to shallow-water corals, which considered multiple assessment metrics and evaluated the potential for post-exposure mortality and/or recovery. Acute and subacute effects (gross morphological changes, photosynthetic efficiency, mortality, and histologic cellular changes) were evaluated during pre-exposure (4 wk), exposure (48 h), and post-exposure recovery (4 wk) periods. Coral condition scores were used to determine a 48-h median effective concentration of 7442 µg/L. Significant physical and histological changes resulted from exposure to 640 µg/L and 5427 µg/L 1-methylnaphthalene, with a 1-d to 3-d delay in photosynthetic efficiency effects (ΔF/Fm). Pigmented granular amoebocyte area was found to be a potentially useful sublethal endpoint for this species. Coral mortality was used to estimate a 48-h median lethal concentration of 12 123 µg/L. Environ Toxicol Chem 2017;36:212-219. © 2016 SETAC.

Growth rates of Florida corals from 1937 to 1996 and their response to climate change.

Ocean acidification causes declines in calcification rates of corals because of decreasing aragonite saturation states (Ω(arag)). Recent evidence also indicates that increasing sea surface temperatures may have already reduced growth and calcification rates because of the stenothermic threshold of localized coral populations. Density banding in coral skeletons provides a record of growth over the coral's lifespan. Here we present coral extension, bulk density and calcification master chronologies from seven subtropical corals (Montastraea faveolata) located in the Florida Keys, USA with a 60-year common period, 1937-1996. Linear trends indicate that extension increased, density decreased and calcification remained stable while the most recent decade was not significantly different than decadal averages over the preceding 50 years for extension and calcification. The results suggest that growth rates in this species of subtropical coral have been tolerant to recent climatic changes up to the time of collection (1996).

Coral reefs: threats and conservation in an era of global change.

Coral reefs are iconic, threatened ecosystems that have been in existence for approximately 500 million years, yet their continued ecological persistence seems doubtful at present. Anthropogenic modification of chemical and physical atmospheric dynamics that cause coral death by bleaching and newly emergent diseases due to increased heat and irradiation, as well as decline in calcification caused by ocean acidification due to increased CO(2), are the most important large-scale threats. On more local scales, overfishing and destructive fisheries, coastal construction, nutrient enrichment, increased runoff and sedimentation, and the introduction of nonindigenous invasive species have caused phase shifts away from corals. Already approximately 20% of the world's reefs are lost and approximately 26% are under imminent threat. Conservation science of coral reefs is well advanced, but its practical application has often been lagging. Societal priorites, economic pressures, and legal/administrative systems of many countries are more prone to destroy rather than conserve coral-reef ecosystems. Nevertheless, many examples of successful conservation exist from the national level to community-enforced local action. When effectively managed, protected areas have contributed to regeneration of coral reefs and stocks of associated marine resources. Local communities often support coral-reef conservation in order to raise income potential associated with tourism and/or improved resource levels. Coral reefs create an annual income in S-Florida alone of over $4 billion. Thus, no conflict between development, societal welfare, and coral-reef conservation needs to exist. Despite growing threats, it is not too late for decisive action to protect and save these economically and ecologically high-value ecosystems. Conservation science plays a critical role in designing effective strategies.

Cellular reactions to sedimentation and temperature stress in the Caribbean coral Montastraea cavernosa.

We present evidence of cellular responses to increased sedimentation and temperature in Montastraea cavernosa collected off Broward County, Florida. We sampled corals from six different sites approximately, 500-1000 m off shore, 10-15m depth. Six samples were collected from four sites adjacent to areas of underwater marine dredging (project sites), while the remaining two samples were obtained far away from the influence of the marine dredging (control sites). SSTs around collection time ranged 0.6-0.9 degrees C over the 40-year monthly mean. All specimens collected at project sites exhibited histopathological evidence of mild to moderate sedimentation stress including changes in size and number of mucocytes in epidermis and gastrodermis, attenuation of the epidermal and gastrodermal tissues, presence of cellular debris, and changes in number of zooxanthellae. These findings corroborate results of laboratory-based, sand-application experiments. In addition to the above-noted changes, one specimen exhibited multiple lesions consisting of unusual gastrodermal detachment with infiltration of amoebocytes into the adjacent mesoglea. Tissues surrounding detachment injuries exhibited marked to severe cellular changes. Accumulations of amoebocytes at lesion sites are seldom observed in wild corals. This response may be part of an organized reaction to injury and infection, as has been documented in sea anemones and gorgonians; however, further research is needed on the nature and role(s) of the scleractinian amoebocytes.

Assessing the accuracy of acoustic seabed classification for mapping coral reef environments in South Florida (Broward County, USA).

The Atlantic coast of Broward County, Florida (USA) is paralleled by a series of progressively deeper, shore-parallel coral reef communities. Two of these reef systems are drowned early Holocene coral reefs of 5 ky and 7 ky uncorrected radiocarbon age. Despite the case of access to these reefs, and their major contribution to the local economy, accurate benthic habitat maps of the area are not available. Ecological studies have shown that different benthic communities (i.e. communities composed of different biological taxa) exist along several spatial gradients on all reefs. Since these studies are limited by time and spatial extent, acoustic surveys with the QTCView V bottom classification system based on a 50 kHz transducer were used as an alternative method of producing habitat maps. From the acoustic data of a 3.1 km(2) survey area, spatial prediction maps were created for the area. These were compared with habitat maps interpreted from in situ data and Laser Airborne Depth Sounder (LADS) bathymetry, in order to ground-truth the remotely sensed data. An error matrix was used to quantitatively determine the accuracy of the acoustically derived spatial prediction model against the maps derived from the in situ and LADS data sets. Confusion analysis of 100 random points showed that the system was able to distinguish areas of reef from areas of rubble and sand with an overall accuracy of 61%. When asked to detect more subtle spatial differences, for example, those between distinct reef communities, the classification was only about 40% accurate. We discuss to what degree a synthesis of acoustic and in situ techniques can provide accurate habitat maps in coral reef environments, and conclude that acoustic methods were able to reflect the spatial extent and composition of at least three different biological communities.