Differential molecular biomarker expression in corals over a gradient of water quality stressors in Maunalua Bay, Hawaii

Coral reefs globally face unprecedented challenges from anthropogenic stressors, necessitating innovative approaches for effective assessment and management. Molecular biomarkers, particularly those related to protein expressions, provide a promising avenue for diagnosing coral health at the cellular level. This study employed enzyme-linked immunosorbent assays to evaluate stress responses in the coral Porites lobata along an environmental gradient in Maunalua Bay, Hawaii. The results revealed distinct protein expression patterns correlating with anthropogenic stressor levels across the bay. Some proteins, such as ubiquitin and Hsp70, emerged as sensitive biomarkers, displaying a linear decrease in response along the environmental gradient, emphasizing their potential as indicators of stress. Our findings highlighted the feasibility of using protein biomarkers for real-time assessment of coral health and the identification of stressors. The identified biomarkers can aid in establishing stress thresholds and evaluating the efficacy of management interventions. Additionally, we assessed sediment and water quality from the inshore areas in the bay and identified organic contaminants, including polycyclic aromatic hydrocarbons and pesticides, in bay sediments and waters.

Characterizing transcriptomic responses to sediment stress across location and morphology in reef-building corals

Anthropogenic activities increase sediment suspended in the water column and deposition on reefs can be largely dependent on colony morphology. Massive and plating corals have a high capacity to trap sediments, and active removal mechanisms can be energetically costly. Branching corals trap less sediment but are more susceptible to light limitation caused by suspended sediment. Despite deleterious effects of sediments on corals, few studies have examined the molecular response of corals with different morphological characteristics to sediment stress. To address this knowledge gap, this study assessed the transcriptomic responses of branching and massive corals in Florida and Hawai'i to varying levels of sediment exposure. Gene expression analysis revealed a molecular responsiveness to sediments across species and sites. Differential Gene Expression followed by Gene Ontology (GO) enrichment analysis identified that branching corals had the largest transcriptomic response to sediments, in developmental processes and metabolism, while significantly enriched GO terms were highly variable between massive corals, despite similar morphologies. Comparison of DEGs within orthogroups revealed that while all corals had DEGs in response to sediment, there was not a concerted gene set response by morphology or location. These findings illuminate the species specificity and genetic basis underlying coral susceptibility to sediments.

The effects of brodifacoum cereal bait pellets on early life stages of the rice coral Montipora capitata

Midway Atoll in the Northwestern Hawaiian Islands is home to ground nesting birds that are threatened by invasive mice. Planned rodent eradication efforts for the island involve aerial application of cereal bait pellets containing the chemical rodenticide brodifacoum. Given the nature of the application method, drift of cereal bait pellets into the coastal waters surrounding Midway Atoll is unavoidable. To understand whether cereal bait pellets impact marine invertebrates, gametes and larvae of the reef-building coral Montipora capitata were exposed to brodifacoum, cereal bait pellets containing brodifacoum, and inert cereal bait pellets without the rodenticide. Fertilization success and larval survival were assessed at nominal brodifacoum concentrations of 1, 10, and 100 ppb. Fertilization success decreased by 15% after exposure to 100 ppb brodifacoum solutions. Larval survival was not reduced by exposure to brodifacoum solutions. Cereal bait pellets containing brodifacoum reduced fertilization success at 10 ppb brodifacoum in 0.4 g per L pellet solutions by 34.84%, and inhibited fertilization at 100 ppb brodifacoum in 4 g of pellet per L solution. Inert cereal bait pellets had similar effects, reducing fertilization success at 0.4 g of pellet per L by 40.50%, and inhibiting fertilization at 4 g per L pellet solutions. Larval survival was reduced by >43% after prolonged exposure to 4 g per L pellet solutions. The highest concentration used in this study was meant to represent an extreme and unlikely condition resulting from an accidental spill. Our findings indicate large amounts of cereal bait pellets entering the coastal environment of Midway Atoll, if occurring during a coral spawning event, would reduce coral reproduction by decreasing fertilization success. It is difficult to know the ecologically relevant concentrations of cereal bait pellets in coastal environments due to unavoidable bait drift after land applications, but results indicate small amounts of pellet drifting into coastal environments would not severely reduce coral reproductive capacity. Best management practices should consider known coral reproductive periods when scheduling applications of pellets on tropical islands to reduce the risk of negative impacts of large-scale accidents on corals.

Water quality thresholds for coastal contaminant impacts on corals: A systematic review and meta-analysis

Reduced water quality degrades coral reefs, resulting in compromised ecosystem function and services to coastal communities. Increasing management capacity on reefs requires prioritization of the development of data-based water-quality thresholds and tipping points. To meet this urgent need of marine resource managers, we conducted a systematic review and meta-analysis that quantified the effects on scleractinian corals of chemical pollutants from land-based and atmospheric sources. We compiled a global dataset addressing the effects of these pollutants on coral growth, mortality, reproduction, physiology, and behavior. The resulting quantitative review of 55 articles includes information about industrial sources, modes of action, experimentally tested concentrations, and previously identified tolerance thresholds of corals to 13 metals, 18 pesticides, 5 polycyclic aromatic hydrocarbons (PAHs), a polychlorinated biphenyl (PCB), and a pharmaceutical. For data-rich contaminants, we make more robust threshold estimates by adapting models for Bayesian hierarchical meta-analysis that were originally developed for biopharmaceutical application. These models use information from multiple studies to characterize the dose-response relationships (i.e., E_max curves) between a pollutant's concentration and various measures of coral health. Metals used in antifouling paints, especially copper, have received a great deal of attention to-date, thus enabling us to estimate the cumulative impact of copper across coral's early life-history. The effects of other land-based pollutants on corals are comparatively understudied, which precludes more quantitative analysis. We discuss opportunities to improve future research so that it can be better integrated into quantitative assessments of the effects of more pollutant types on sublethal coral stress-responses. We also recommend that managers use this information to establish more conservative water quality thresholds that account for the synergistic effects of multiple pollutants on coral reefs. Ultimately, active remediation of local stressors will improve the resistance, resilience, and recovery of individual reefs and reef ecosystems facing the global threat of climate change.

Chronic Exposure to 4-Nonylphenol Alters UDP-Glycosyltransferase and Sulfotransferase Clearance of Steroids in the Hard Coral, Pocillopora damicornis

The effects of the xenoestrogen 4-nonylphenol (4NP) on endocrine and metabolic homeostasis in the reef building coral, Pocillopora damicornis were investigated. The aim was to understand if ubiquitous nonylphenol ethoxylate contaminants in the marine environment result in altered homeostatic function. Coral colonies were chronically exposed (6 weeks) to a sublethal concentration (1 ppb) of 4NP and sampled over the coral's lunar reproductive cycle. Although activity of steroidogenic enzymes [cytochrome P450 (CYP) 17, CYP 19, and 3-β-Hydroxysteroid dehydrogenase] and the conjugation enzyme glutathione-S-transferase was not altered, significant increases in the activity of the steroid clearing enzyme UDP-glycosyltransferase (UGT) were observed. The natural fluctuation of UGT activity with the lunar cycle was replaced with consistently high UGT activity throughout the reproductive cycle during 4NP exposure. No effect of 4NP on the reverse reaction, mediated by β-glucuronidase, was observed. Thus, 4NP shifts the UGT:β-glucuronidase ratio toward greater clearance at points in the lunar cycle where retention of compounds is typically favored. Additionally, 4NP reduced activity of the steroid regeneration enzyme steroid sulfatase, further shifting the system toward clearance rather than regeneration. These data imply that environmentally relevant levels of 4NP may be impacting the reproductive health of corals and threatening the persistence of coral reefs.

Genetic structure is stronger across human-impacted habitats than among islands in the coral Porites lobata

We examined genetic structure in the lobe coral Porites lobata among pairs of highly variable and high-stress nearshore sites and adjacent less variable and less impacted offshore sites on the islands of Oahu and Maui, Hawaii. Using an analysis of molecular variance framework, we tested whether populations were more structured by geographic distance or environmental extremes. The genetic patterns we observed followed isolation by environment, where nearshore and adjacent offshore populations showed significant genetic structure at both locations (AMOVA F ST = 0.04∼0.19, P < 0.001), but no significant isolation by distance between islands. Strikingly, corals from the two nearshore sites with higher levels of environmental stressors on different islands over 100 km apart with similar environmentally stressful conditions were genetically closer (FST = 0.0, P = 0.73) than those within a single location less than 2 km apart (FST = 0.04∼0.08, P < 0.01). In contrast, a third site with a less impacted nearshore site (i.e., less pronounced environmental gradient) showed no significant structure from the offshore comparison. Our results show much stronger support for environment than distance separating these populations. Our finding suggests that ecological boundaries from human impacts may play a role in forming genetic structure in the coastal environment, and that genetic divergence in the absence of geographical barriers to gene flow might be explained by selective pressure across contrasting habitats.

Antioxidant enzyme cycling over reproductive lunar cycles in Pocillopora damicornis

The impacts of continued degradation of watersheds on coastal coral reefs world-wide is alarming, and action addressing anthropogenic stressors and subsequent rehabilitation of watersheds and adjacent reefs is an urgent priority. The aim of this study is to develop and improve the use of antioxidant enzymes as bioindicators of stress in coral species. In order to fully develop such tools, it is necessary to first understand baseline cycling of these enzymes within coral tissues. Due to inherent links between reproduction and oxidative stress, these aims may be facilitated by sampling coral tissues over reproductively-linked lunar cycles to determine variations from baseline. By developing a greater understanding of biochemical markers of stress in corals, specifically antioxidant defense enzymes catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and superoxide dismutase (SOD) in Hawaiian Pocillopora damicornis, we have provided molecular tools that identify thresholds of stress on coral reefs. Our results suggest that the coral reproductive state is a significant factor affecting the activity of antioxidant enzymes. Specifically, CAT and GR display maximum activity during peak reproductive state. Whereas significant maximal Se-independent GPx and SOD activity was measured during off-peak reproductive cycles. Such insight into the cyclical variation of the activity of these enzymes should be applied towards differentiating the influence of natural biological activity cycling in diagnostic tests identifying the effects of different physical environmental factors and chemical pollutants on coral health. Through the development and application of these molecular biomarkers of stress, we look to improve our ability to identify problems at the sub-lethal level, when action can be taken to mitigate a/biotic impacts.

Addressing Criticisms of Large-Scale Marine Protected Areas

Designated large-scale marine protected areas (LSMPAs, 100,000 or more square kilometers) constitute over two-thirds of the approximately 6.6% of the ocean and approximately 14.5% of the exclusive economic zones within marine protected areas. Although LSMPAs have received support among scientists and conservation bodies for wilderness protection, regional ecological connectivity, and improving resilience to climate change, there are also concerns. We identified 10 common criticisms of LSMPAs along three themes: (1) placement, governance, and management; (2) political expediency; and (3) social-ecological value and cost. Through critical evaluation of scientific evidence, we discuss the value, achievements, challenges, and potential of LSMPAs in these arenas. We conclude that although some criticisms are valid and need addressing, none pertain exclusively to LSMPAs, and many involve challenges ubiquitous in management. We argue that LSMPAs are an important component of a diversified management portfolio that tempers potential losses, hedges against uncertainty, and enhances the probability of achieving sustainably managed oceans.

Changes to coral health and metabolic activity under oxygen deprivation

On Hawaiian reefs, the fast-growing, invasive algae Gracilaria salicornia overgrows coral heads, restricting water flow and light, thereby smothering corals. Field data shows hypoxic conditions (dissolved oxygen (DO₂) < 2 mg/L) occurring underneath algal mats at night, and concurrent bleaching and partial tissue loss of shaded corals. To analyze the impact of nighttime oxygen-deprivation on coral health, this study evaluated changes in coral metabolism through the exposure of corals to chronic hypoxic conditions and subsequent analyses of lactate, octopine, alanopine, and strombine dehydrogenase activities, critical enzymes employed through anaerobic respiration. Following treatments, lactate and octopine dehydrogenase activities were found to have no significant response in activities with treatment and time. However, corals subjected to chronic nighttime hypoxia were found to exhibit significant increases in alanopine dehydrogenase activity after three days of exposure and strombine dehydrogenase activity starting after one overnight exposure cycle. These findings provide new insights into coral metabolic shifts in extremely low-oxygen environments and point to ADH and SDH assays as tools for quantifying the impact of hypoxia on coral health.

Predicting dredging-associated effects to coral reefs in Apra Harbor, Guam - Part 2: Potential coral effects

Coral reefs are in decline worldwide due to anthropogenic stressors including reductions in water and substratum quality. Dredging results in the mobilization of sediments, which can stress and kill corals via increasing turbidity, tissue damage and burial. The Particle Tracking Model (PTM) was applied to predict the potential impacts of dredging-associated sediment exposure on the coral reef ecosystems of Apra Harbor, Guam. The data were interpreted using maps of bathymetry and coral abundance and distribution in conjunction with impact parameters of suspended sediment concentration (turbidity) and sedimentation using defined coral response thresholds. The results are presented using a "stoplight" model of negligible or limited impacts to coral reefs (green), moderate stress from which some corals would be expected to recover while others would not (yellow) and severe stress resulting in mortality (red). The red conditions for sediment deposition rate and suspended sediment concentration (SSC) were defined as values exceeding 25 mg cm(-2) d(-1) over any 30 day window and >20 mg/l for any 18 days in any 90 day period over a column of water greater than 2 m, respectively. The yellow conditions were defined as values >10 mg cm(-2) d(-1) and <25 mg cm(-2) d(-1) over any 30 day period, and as 20% of 3 months' concentration exceeding 10 mg/l for the deposition and SSC, respectively. The model also incorporates the potential for cumulative effects on the assumption that even sub-lethal stress levels can ultimately lead to mortality in a multi-stressor system. This modeling approach can be applied by resource managers and regulatory agencies to support management decisions related to planning, site selection, damage reduction, and compensatory mitigation.

Molecular reproductive characteristics of the reef coral Pocillopora damicornis

Coral reefs are an indispensible worldwide resource, accounting for billions of dollars in cultural, economic, and ecological services. An understanding of coral reproduction is essential to determining the effects of environmental stressors on coral reef ecosystems and their persistence into the future. Here, we describe the presence of and changes in steroidal hormones along with associated steroidogenic and steroid removal enzymes during the reproductive cycle of the brooding, pan-Pacific, hermaphroditic coral, Pocillopora damicornis. Detectable levels of 17β-estradiol, estrone, progesterone and testosterone were consistently detected over two consecutive lunar reproductive cycles in coral tissue. Intra-colony variation in steroid hormone levels ranged between 1.5- and 2.2-fold and were not statistically different. Activities of the steroidogenic enzymes 3β-hydroxysteroid dehydrogenase and cytochrome P450 (CYP) 17 dehydrogenase were detectable and did not fluctuate over the reproductive cycle. Aromatase-like activity was detected during the lunar reproductive cycle with no significant fluctuations. Activities of regeneration enzymes did not fluctuate over the lunar cycle; however, activity of the clearance enzyme UDP-glucuronosyl transferases increased significantly (ANOVA, post hoc p<0.01) during the two weeks before and after peak larval release (planulation), suggesting that the activity of this enzyme family may be linked to the reproductive state of the coral. Sulfotransferase enzymes could not be detected. Our findings provide the first data defining normal physiological and lunar/reproductive variability in steroidal enzymes in a coral species with respect to their potential role in coral reproduction.

Heat-stress and light-stress induce different cellular pathologies in the symbiotic dinoflagellate during coral bleaching

Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m⁻² s⁻¹ PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching.

Predicting coral recruitment in Palau's complex reef archipelago

Reproduction and recruitment are key processes that replenish marine populations. Here we use the Palau archipelago, in the western Pacific Ocean, as a case study to examine scales of connectivity and to determine whether an oceanographic model, incorporating the complex reef architecture, is a useful predictor of coral recruitment. We tested the hypothesis that the reefs with the highest retention also had the highest densities of juvenile coral density from 80 field sites. Field comparisons showed a significant correlation between the densities of juvenile Acropora colonies and total larval recruitment derived from the model (i.e., calculated as the sum of the densities of larvae that self-seeded and recruited from the other reefs in the archipelago). Long-distance larval imports may be too infrequent to sustain coral populations, but are critical for recovery in times of extreme local stress.

The preparation of the rice coral Montipora capitata nubbins for application in coral-reef ecotoxicology

Securing adequate and appropriate source material for coral-reef ecotoxicology studies is a significant impediment to conducting various experiments supporting the goal of conserving coral-reef ecosystems. Collecting colonies from wild stocks may be counter to protecting coral reef populations. To address this issue the rice coral Montipora capitata was used to generate sufficient genetically identical nubbins for research purposes. Growth and survival rates of these laboratory-prepared M. capitata nubbins were studied over a period of 90 days. The resulting data support the conclusion that the laboratory-prepared M. capitata nubbins showed successful growth and survival rates and are the best solution to solve the source material issue for lab experimentation. This paper describes the laboratory method used for the preparation and maintenance of these M. capitata nubbins and discusses the benefits and difficulties of using these nubbins in ecotoxicity studies.

The use of cellular diagnostics for identifying sub-lethal stress in reef corals

Coral reefs throughout the world are exhibiting documented declines in coral cover and species diversity, which have been linked to anthropogenic stressors including land-based sources of pollution. Reductions in coastal water and substratum quality are affecting coral survivorship, reproduction and recruitment, and hence, the persistence of coral reefs. One major obstacle in effectively addressing these declines is the lack of tools that can identify cause-and-effect relationships between stressors and specific coral reef losses, while a second problem is the inability to measure the efficacy of mitigation efforts in a timely fashion. We examined corals from six coral reefs on Guam, Mariana Islands, which were being affected by different environmental stressors (e.g. PAH's, pesticides, PCB's and sedimentation). Cellular diagnostic analysis differentiated the cellular-physiological condition of these corals. Examination of protein expression provided insight into their homeostatic responses to chemical and physical stressors in exposed corals prior to outright mortality, providing improved opportunities for developing locally-based management responses. This approach adds critically needed tools for addressing the effects of multiple stressors on corals and will allow researchers to move beyond present assessment and monitoring techniques that simply document the loss of coral abundance and diversity.

Oxidative DNA damage induced by iron chloride in the larvae of the lace coral Pocillopora damicornis

Biochemical and molecular biomarkers tools are utilized as early warning signatures of contaminant exposure to target and non-target organisms. The objective of this study was to investigate the sublethal effects of iron chloride to the larvae of the lace coral Pocillopora damicornis by measuring a suit of oxidative-stress biomarkers. The larvae were exposed to a range of sublethal concentrations of iron chloride (0.01, 0.1, 1, 10, and 100 ppm) for seven days. With reference to oxidative stress biomarkers, the no-observed effect concentration (NOEC) and the lowest observed effect concentration (LOEC) of iron chloride were observed to be 0.01 and 100 ppm respectively. At the end of the seventh day the antioxidant status of the larvae was evaluated by the levels of glutathione (GSH), glutathione peroxidase (GPX), glutathione reductase (GR), and glutathione-S-transferase (GST), in both experimental and control groups. For the quantification of cellular oxidative damage, lipid peroxidation (LPO) activity was determined in the same and the extent of DNA damage was assessed by the expression of DNA apurinic/apyrimidinic (AP) sites. Iron chloride exhibited a concentration-dependent inhibition of GSH and GPX and induction of GR, GST, LPO, and DNA-AP sites in the P. damicornis larvae when compared to the control group. The oxidative stress biomarkers of the larvae exposed to 0.1, 1, and 10 ppm of iron chloride did not show any significant overall differences when compared to the control group. However the activities of LPO, GSH, GPX, GR, GST and DNA-AP in the larval group exposed to 100 ppm of iron chloride exhibited statistically significant (P=0.002, 0.003, 0.002, 0.002, 0.005 and 0.007) differences when compared to the control group. The research results indicated that iron chloride in concentrations at the 100 ppm level caused oxidative stress in the P. damicornis larvae.

Concentrations of Irgarol in selected marinas of Oahu, Hawaii and effects on settlement of coral larval

This study examined concentrations of Irgarol 1051(®) in selected marinas on the island of Oahu, Hawaii and used laboratory bioassays to assess effects of Irgarol on coral larval settlement. Field surveys of small boat marinas performed in 2006-2007 revealed low concentrations of Irgarol 1051(®), an antifouling paint additive, ranging from non-detected (<17 ng/l) to 283 ng/l. The highest concentrations of Irgarol 1051(®) were found in marinas with low flushing rates and a high density of moored boats and boat traffic. The potential effect of Irgarol 1051(®) on coral larval settlement was evaluated in the laboratory using planulae from Porites hawaiiensis, a zooxanthellate shade-dwelling coral found in Hawaiian waters. Exposure to Irgarol 1051(®) at 100 ng/l resulted in a statistically significant reduction in settlement of coral larvae. This was within the range of Irgarol 1051(®) concentrations found in some of the marinas surveyed on the island of Oahu but Irgarol was not detected in seawater samples at offshore reefs.

River discharge reduces reef coral diversity in Palau

Coral community structure is often governed by a suite of processes that are becoming increasingly influenced by land-use changes and related terrestrial discharges. We studied sites along a watershed gradient to examine both the physical environment and the associated biological communities. Transplanted corals showed no differences in growth rates and mortality along the watershed gradient. However, coral cover, coral richness, and coral colony density increased with increasing distance from the mouth of the bay. There was a negative relationship between coral cover and mean suspended solids concentration. Negative relationships were also found between terrigenous sedimentation rates and the richness of adult and juvenile corals. These results have major implications not only for Pacific islands but for all countries with reef systems downstream of rivers. Land development very often leads to increases in river runoff and suspended solids concentrations that reduce coral cover and coral diversity on adjacent reefs.

Establishment, characterization, and viral susceptibility of two cell lines derived from goldfish Carassius auratus muscle and swim bladder

Goldfish Carassius auratus are common aquarium fish and have a significant economic and research value, having considerable worth to fisheries as a baitfish and the ability to adapt to a range of habitats. Two cell lines were established from goldfish muscle and swim bladder tissue, in order to create a biological monitoring tool for viral diseases. Cell lines were optimally maintained at 30 degrees C in Leibovitz-15 medium supplemented with 20% fetal bovine serum. Propagation of goldfish cells was serum dependent, with a low plating efficiency (>16%). Karyotyping analysis indicated that both cell lines remained diploid, with a mean chromosomal count of 104. Results of viral challenge assays revealed that both cell lines shared similar patterns of viral susceptibility and production to infectious hematopoietic necrosis virus, infectious pancreatic necrosis virus, snakehead rhabdovirus, and spring viremia carp virus. Both cell lines demonstrated a higher sensitivity and significantly larger viral production than control brown bullhead cells for channel catfish virus. These newly established cell lines will be used as a diagnostic tool for viral diseases in this fish species and also for the isolation and study of goldfish viruses in the future.

Cellular physiological effects of the MV Kyowa violet fuel-oil spill on the hard coral, Porites lobata

The grounding of the Merchant Vessel (MV) Kyowa Violet on a coral reef near Yap, Federated States of Micronesia, in December 2002 resulted in the release of an estimated 55,000 to 80,000 gallons of intermediate fuel oil grade 180. The immediate impact was the widespread coating of mangroves and the intertidal zone along more than 8 km of coastline. Of greater concern, however, was the partitioning of the fuel oil in the water column, leading to chronic exposure of organisms in the ecosystem for a considerable period after the initial event. Herein, we report on our examination of one coral species, Porites lobata, nearly three months after the initial exposure. We investigated whether changes in cellular physiology were consistent with the pathological profile that results from the interaction of corals with polycyclic aromatic hydrocarbons, the principal constituent of fuel oil. Specifically, we document, to our knowledge for the first time, changes in the cellular physiological condition of an exposed coral population affected by a fuel-oil spill. We also provide evidence that the observed changes are consistent with a recent exposure to fuel oil, as evidenced by the presence of characteristic cellular lesions attributed to polycyclic aromatic hydrocarbons. Finally, our data support a model for a mechanistic relationship between the cellular pathological profile of the coral and a recent petroleum exposure, such as the MV Kyowa Violet fuel oil spill.

Alteration of normal cellular profiles in the Scleractinian coral (Pocillopora damicornis) following laboratory exposure to fuel oil

Petroleum contamination from oil spills is a continuing threat to our ocean's fragile ecosystems. Herein, we explored the effects of the water-soluble fraction of crude oil on a stony coral, Pocillopora damicornis (Linneaeus 1758). We developed methods for exposing corals to various concentrations of crude oil and for assessing the potential molecular responses of the corals. Corals were exposed to water-accommodated fraction solutions, and appropriate cellular biomarkers were quantified. When compared to the "healthy" control specimens, exposed corals exhibited shifts in biomarker concentrations that were indicative of a shift from homeostasis. Significant changes were seen in cytochrome P450 1-class, cytochrome P450 2-class, glutathione-S-transferase-pi, and cnidarian multixenobiotic resistance protein- biomarkers, which are involved the cellular response to, and manipulation and excretion of, toxic compounds, including polycyclic aromatic hydrocarbons. A shift in biomarkers necessary for porphyrin production (e.g., protoporphyrinogen oxidase IX and ferrochelatase) and porphyrin destruction (e.g., heme oxygenase-1 and invertebrate neuroglobin homologue) illustrates only one of the cellular protective mechanisms. The response to oxidative stress was evaluated through measurements of copper/zinc superoxide dismutase-1 and DNA glycosylase MutY homologue-1 concentrations. Likewise, changes in heat shock protein 70 and small heat shock proteins indicated an adjustment in the cellular production of proteins. Finally, the results of this laboratory study were nearly identical to what we observed previously among corals of a different species, Porites lobata, exposed to an oil spill in the field after the grounding of the Merchant Vessel Kyowa Violet.

Characterization of the telomere regions of scleractinian coral, Acropora surculosa

Terminal ends of vertebrate chromosomes are protected by tandem repeats of the sequence (TTAGGG). First thought to be vertebrate specific, (TTAGGG)( n ) has recently been identified in several aquatic invertebrates including sea urchin (Strongylocentrotus purpuratus), bay scallop (Argopecten irradians), and wedgeshell clam (Donax trunculus). We analyzed genomic DNA from scleractinian corals, Acropora surculosa, Favia pallida, Leptoria phrygia, and Goniastrea retiformis to determine the telomere sequence. Southern blot analysis suggests the presence of the vertebrate telomere repeats in all four species. Treatment of A. surculosa sperm DNA with Bal31 exonuclease revealed progressive shortening of the DNA fragments positive for the (TTAGGG)(22) sequence, supporting location of the repeats at the chromosome ends. The presence of the vertebrate telomere repeats in corals is evidence that the (TTAGGG)( n ) sequence is highly conserved among a divergent group of vertebrate and invertebrate species. Corals are members of the Lower Metazoans, the group of organisms that span the gap between the fungi and higher metazoans. Corals are the most basal organism reported to have the (TTAGGG)( n ) sequence to date, which suggests that the vertebrate telomere sequence may be much older than previously thought and that corals may share a number of genes with their higher relatives.

Shifting the paradigm of coral-reef 'health' assessment

Coral reefs are in crisis. Globally, our reefs are degrading at an accelerating rate and present methodologies for coral-reef 'health' assessment, although providing important information in describing these global declines, have been unable to halt these declines. These assessments are usually employed with no clear purpose and using uncorrelated methods resulting in a failure to prevent or mitigate coral reef deterioration. If we are to ever successfully intervene, we must move beyond the current paradigm, where assessments and intervention decisions are based primarily on descriptive science and embrace a paradigm that promotes both descriptive and mechanistic science to recognize a problem, and recognize it before it becomes a crisis. The primary methodology in this alternative paradigm is analogous to the clinical and diagnostic methodologies of evidence-based medicine. Adopting this new paradigm can provide the evidence to target management actions on those stressors currently impacting reef ecosystems as well as providing a means for proactive management actions to avert irreversible habitat decline.