Hermatypic Research Articles

Spatio-temporal variation in rate of carbonate deposition by encrusting organisms in different reef microhabitats from Eastern Pacific coral reefs

AbstractReef encrusting calcifiers (non-scleractinian species) constitute assemblages that participate in the carbon cycle at coral reefs. Despite their apparent secondary role in building the reef framework, they contribute to the reef consolidation binding sediments and inducing larval recruitment from other epilithic invertebrates. The contribution of encrusting calcifiers on reef accretion was examined by the assessment of their rate of carbonate deposition on four different simulated reef microhabitats using calcification accretion units (CAUs) during 12 months at Playa Las Gatas and Islote Zacatoso, two coral communities from the coast of the Mexican Pacific. Encrusting calcifiers from Playa Las Gatas, the most impacted site, showed a rate of carbonate deposition (mean ± SD) four times higher than at Islote Zacatoso (10.02 ± 3.22 g CaCO3m−2d−1vs2.48 ± 1.01 g CaCO3m−2d−1). Overall, the rate of carbonate deposition on surfaces protected from sedimentation and light was up to 1.8 times higher than on exposed ones (11.40 ± 4.35 g CaCO3m−2d−1vs6.18 ± 3.13 g CaCO3m−2d−1). Carbonate deposition by calcareous algae was higher on the well-lit exposed surfaces while filter-feeding invertebrates showed the major contribution on the shaded cryptic surfaces. Although rate of carbonate deposition by encrusting calcifiers seems to be lower than hermatypic corals, it seems to be relevant on coral reefs affected by anthropogenic impacts where coral calcification is low. Under global demise of coral reefs by environmental degradation and climate change, encrusting calcifiers may become relevant for the process of carbonate deposition.

Living on the edge: Assessing the diversity of South African Pocillopora on the margins of the Southwestern Indian Ocean.

Scleractinia of the Maputaland reef complex (MRC) in South Africa exist at the margins of the Western Indian Ocean (WIO) coral distribution and are the only substantial hermatypic coral communities in South Africa. Pocillopora species occupy a conspicuous component of the MRC, and previous investigations identified three species of Pocillopora utilizing conventional taxonomy. Thus, our aims were four-fold: to elucidate Pocillopora species diversity using genetic techniques, primarily using species delimitation methods based on the ORF gene; to test for the presence of hybridisation within the Pocillopora community on the South-West margin of distribution in the Indian Ocean using two nuclear and two mitochondrial markers; to test the presence of cryptic species, using 13 microsatellite markers, finally, to elucidate the degree of genetic diversity within each Pocillopora species found and compare this to communities in lower latitudes. We illustrate taxonomic inconsistencies between these inventories and our phylogenetic data. The MRC harbours unique populations of Pocillopora, consisting of three species hypothetically co-occurring throughout the south WIO, namely: P. meandrina/P. eydouxi, commonly misidentified as P. verrucosa, P. verrucosa, sometimes correctly identified, but also commonly misidentified as P. damicornis sensu lato, and P. villosa, almost always misidentified as P. eydouxi. The hypothesis that hybrid swarms of Pocillopora occur in marginal environments such as the MRC was not supported, with low levels of introgressive hybridization reported instead. Analyses illustrate low genetic diversity at the species and population resolutions, suggesting a small founder population for each species. Nevertheless, these populations are demographically unique, exhibiting high levels of ITS2 haplotype endemism compared to higher latitude populations and the rest of the WIO. Pocillopora diversity on the MRC represents a unique assemblage and warrants further protection.

Experimental Approaches for the Evaluation of Allelopathic Interactions Between Hermatypic Corals and Marine Benthic Cyanobacteria in the Colombian Caribbean

Blooms of marine benthic cyanobacteria are recurrent in several locations at the Colombian Caribbean. In these events, cyanobacteria grow over the substrate and benthic organisms although their effect has not been fully assessed. This study evaluated interactions between cyanobacteria and hermatypic corals, in order to identify any deleterious effects that could be related to allelopathic mechanisms. Organic extracts from cyanobacteria collected in San Andres, Old Providence and Rosario islands were tested against embryos of the reef-building coral Orbicella annularis. The indirect effect of cyanobacterial extracts was also assessed by resuspending the extracts in seawater and monitoring polyp retraction and recovery of the coral Madracis mirabilis (=auretenra). Additionally, the effect of direct contact between cyanobacterial extracts and the coral Porites porites was assessed by incorporating cyanobacterial extracts into PhytagelTM gels and placed in direct contact with the coral. After 24, 48 and 72 h of exposure, chromatographic profiles of associated zooxanthellae was evaluated by HPLC. A deleterious effect on the zooxanthellae was evidenced by an increase in pheophytin, a degradation product from chlorophyll. The competitive abilities of algae and cyanobacteria should be considered as a constraint to reef restoration initiatives. Cyanobacteria have the ability to compete with corals due to their growth rates, defenses against herbivory and potentially allelopathic mechanisms.

Electrophysiological evidence for light-activated cation transport in calcifying corals.

Light has been demonstrated to enhance calcification rates in hermatypic coral species. To date, it remains unresolved whether calcifying epithelia change their ion transport activity during illumination, and whether such a process is mediated by the endosymbiotic algae or can be controlled by the coral host itself. Using a modified Ussing chamber in combination with H+ sensitive microelectrode measurements, the present work demonstrates that light triggers the generation of a skeleton positive potential of up to 0.9 mV in the hermatypic coral Stylophora pistillata. This potential is generated by a net flux of cations towards the skeleton and reaches its maximum at blue (450 nm) light. The effects of pharmacological inhibitors targeting photosynthesis 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and anion transport 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) were investigated by pH microelectrode measurements in coral tissues demonstrating a rapid decrease in tissue pH under illumination. However, these inhibitors showed no effect on the electrophysiological light response of the coral host. By contrast, metabolic inhibition by cyanide and deoxyglucose reversibly inhibited the light-induced cation flux towards the skeleton. These results suggest that ion transport across coral epithelia is directly triggered by blue light, independent of photosynthetic activity of algal endosymbionts. Measurements of this very specific and quantifiable physiological response can provide parameters to identify photoreception mechanisms and will help to broaden our understanding of the mechanistic link between light stimulation and epithelial ion transport, potentially relevant for calcification in hermatypic corals.

Usage of UV-curable oligomer-based adhesive agent in hermatypic coral experimental research

The global decline of the tropical and subtropical coral reefs requires urgent completion of various experiments that will reveal the factors influencing coral health. We describe the procedure of a new inexpensive, easy, and fast method for attaching fragments of the hermatypic coral Acropora spp. to small polycarbonate hexagon head bolts using Bondic®, an ultraviolet (UV)-curable oligomer-based adhesive agent made by Laser Bonding Tech, Inc. (Aurora, ON, Canada). The attachment was hardened within 10 s after applying the adhesive to the cut surface of the coral fragment. The corals attached to polycarbonate bolt were tolerant to long-distance aerial transport 3 days after the attachment. In addition to its implementation in various experiments using hermatypic corals, this method will contribute to aquaculture of hermatypic corals, exhibition of corals in aquariums, and coral reef restoration.The advantages of this new method are summarized below:•A new UV-curable oligomer-based adhesive agent is used as an artificial substrate for coral.•This method is inexpensive, easy to use, and coral attaches quickly to the artificial substrate.•Corals attached to the artificial substrate can withstand long periods of transportation.

Early Miocene shallow-water corals from La Guajira, Colombia: Part II, Mussidae–Siderastreidae and Milleporidae

AbstractIn this contribution we describe and illustrate 14 coral morphospecies collected from the early Miocene Siamaná (Aquitanian–Burdigalian) and Jimol (late Burdigalian) formations of the Cocinetas Basin in La Guajira Peninsula, northern Colombia. Eleven were identified as already established species including seven genera belonging to the families Mussidae, Pocilloporidae, Poritidae, Siderastreidae, and Milleporidae; the other three remain in open nomenclature. Nine of the 11 species identified (81%) are extinct. The remaining two living species,Siderastrea sidereaandMillepora alcicornis, are common on modern Caribbean reefs. Their presence in the Siamaná Formation extends their temporal range in the Caribbean region to the early Miocene. Most of the taxa described here were hermatypic and zooxanthellate corals of the order Scleractinia, with the exception of the fire coralMillepora alcicornis, of the order Anthothecata, family Milleporidae. The coral fauna recorded in the Siamaná and Jimol formations is typical of shallow and calm waters of the Oligocene–Miocene transition.

Ferromagnetic Resonance Spectroscopy and Rock Magnetic Characterization of Fossil Coral Skeletons in Ishigaki Islands, Japan

Skeletons of hermatypic corals (e.g., Porites) might have enormous potential as a high-resolution paleomagnetic recorder owing to their rapid and continuous growth over hundreds of years at a rate of up to 2 cm/year, although typical corals show an extremely weak intensity of remanence and low stability. We found that coral tsunami boulders with negligible amounts of calcite on Ishigaki Island show a measurable intensity of remanence; thus, we attempted to characterize the magnetic assemblages in this coral skeleton to determine whether it is of biogenic or detrital magnetite using first-order reversal curve (FORC) measurements, ferromagnetic resonance (FMR) spectroscopy, and petrological observations through field-emission type scanning electron microscope (FE-SEM) with an acid treatment. The FMR derivative spectra of coral skeleton samples represent multiple derivative maxima and extended low-field absorption, indicating the presence of intact biogenic magnetite chains. FORC diagrams represent a “central ridge” signature with a vertical spread. These FMR and FORC features indicate the magnetization of these coral skeletons that are mainly created using intact biogenic magnetites and mixtures of grains from collapsed biogenic magnetites, pseudo-single domain grains, and multi-domain grains such as detrital magnetite. FE-SEM observations confirm the presence of a chain-like structure of iron oxides corresponding to the features of biogenic magnetite. Therefore, the magnetic mineral assemblage in coralline boulders from Ishigaki Island consists of dominant biogenic-origin single-domain magnetite and a trace amount of detrital component, indicating that fossil coral skeletons in Ishigaki Island have potential for utilization in paleomagnetic studies.

Five new coexisting species of copepod crustaceans of the genus Spaniomolgus (Poecilostomatoida: Rhynchomolgidae), symbionts of the stony coral Stylophorapistillata (Scleractinia).

Spaniomolgus is a symbiotic genus of copepods of the poecilostomatoid family Rhynchomolgidae and is known to be associated with shallow-water reef-building hermatypic corals. Three species of this genus were previously found only in washings of Acropora and Stylophora in northern Madagascar. Four coral morphotypes of Stylophorapistillata (Pocilloporidae) were collected by SCUBA at 1 to 28 m depth in five sites in the Saudi Arabian Red Sea in 2013. Copepods found on these colonies were studied using light, confocal and scanning electron microscopy. Five new, and one known, species of the genus Spaniomolgus were discovered in washings and inside the galls of the hermatypic coral S.pistillata. The description of these new species (Spaniomolgusglobussp. n., S.stylophorussp. n., S.dentatussp. n., S.maculatussp. n., and S.acutussp. n.) and a key for the identification of all of its congeners is provided herein.

Assessing coral stress responses using microarray

Storms inflict damage to corals resulting in fragments that have the potential to regenerate thus contributing to the asexual reproduction of the parental colony. Extreme climatic events like these are predicted to increase in the future due to ocean warming, which is also the primary cause of coral reef bleaching and consequent coral mortality in the tropical and subtropical seas. This way it is urgent to investigate the differential effect of warming over post-fragmentation and regeneration processes among the scleractinian hermatypic coral species. This study investigated the mortality, growth and regeneration capacity of nine reef-forming coral species of the Indo-Pacific. Fragments were exposed to 26 °C, 30 °C, and 32 °C for 60 days. Half of these fragments was inflicted with one injury and the other half was used as control. Mortality, partial mortality, bleaching level, growth and regeneration of artificial injuries were assessed. Mortality increased with temperature, reaching 100% for most species after 60 days, at 32 °C, but Psammocora contigua which showed remarkably lower mortality (40%) and all coral fragments of Turbinaria reniformis and Galaxea fascicularis survived the experiment. Partial mortality was lowest for P. contigua, T. reniformis, and G. fascicularis even at 32 °C. These three coral species were also the most resistant to bleaching. Growth rates decreased with temperature, with the exception of G. fascicularis that maintained similar growth rates at 26 °C and 30 °C. Regeneration rates generally increased with temperature. It was concluded that P. contigua, T. reniformis, and G. fascicularis fragments show higher capacity to withstand higher temperatures.

Reconstruction of anthropogenic 129I temporal variation in the Japan Sea using a coral core sample

The anthropogenic long-lived radionuclide 129I is receiving increased attraction as a new oceanic tracer in addition to usage as a fingerprint of radionuclide contamination of the marine environment. To demonstrate the robustness of 129I as an oceanic tracer in the Northwest Pacific area, specifically in the Japan Sea, the input history of 129I to surface seawater was reconstructed using a hermatypic coral core sample from Iki Island in the Tsushima strait. Iodine isotopes in each annual band were measured using AMS and ICP-MS after appropriate pre-treatments of small amounts of coral powder. The 129I/127I ratios in the 1940s were almost at background levels (<1 × 10−11) and increased abruptly in the early 1950s. Thereafter, the ratios continuously increased with some fluctuations; the maximum ratio, 7.13 ± 0.72 × 10−11, being found in the late 1990s. After that period, the ratios remained nearly constant until the present time (2011). The 129I originated mainly from the nuclear weapons testings of the 1950s and the early 1960s, and from airborne releasing by nuclear reprocessing facilities. The dataset obtained here was used to construct a simple model to estimate the diffusion coefficient of 129I in the Japan Sea. The 129I/236U ratios over the observation period were also reconstructed to help constraining sources of 129I to the marine environment. Based on the results, the 129I/236U ratio obtained here could be an endmember of the water mass in the Kuroshio Current area of the Northwest Pacific Ocean.

Facilitation of Australia’s southernmost reef-building coral by sea urchin herbivory

Competition for space between corals and macroalgae represents a key threatening process for coral reefs, yet the influence of climate change on this competitive interaction is poorly understood, particularly at the poleward margins of coral distribution. Here we describe the discovery of Australia’s southernmost hermatypic corals and explore novel dynamics facilitating the presence and extent of high-latitude coral communities. Examination of 607 shallow reef sites across temperate Australia revealed hard corals to be negatively associated with increasing kelp bed cover, but positively associated with increasing sea surface temperature, herbivorous fishes, grazing sea urchins, and increasing cover of turf algae, which proliferates in the absence of kelp. However, the nature of these effects varied across different regions of temperate Australia consistent with regional variability in the presence/absence of key functional groups for temperate reefs, such as guilds of subtropical herbivorous fishes and/or prevalence of overgrazing sea urchins. For the southernmost coral communities, in eastern Bass Strait Tasmania, the dominant reef-building coral Plesiastrea versipora was negatively associated with kelp and positively associated with the southward range-extending diadematid sea urchin Centrostephanus rodgersii, which has caused extensive kelp bed overgrazing since first locally reported in 1974. Facilitation of coral establishment was strongest on overgrazed barrens where urchin density was relatively low, but sufficient to maintain the reef kelp-free, while corals were less frequent at high urchin densities and completely absent from barrens colonised by intensively grazing limpets. In contrast to tropical Australian coral reefs and other temperate regions (e.g. Western Australia), assays of herbivory confirmed sea urchin grazing, not herbivorous fishes, as chiefly responsible for kelp consumption within this high-latitude system. Size structure of P. versipora in eastern Bass Strait was dominated by small colonies (~ 20 cm2), suggesting an expanding population at the poleward edge of the species’ range. Nevertheless, colonies up to a maximum area of 500 cm2 were observed, which are likely > 40 yrs old based on growth rates established in warmer waters. This research highlights novel patterns and processes structuring the interface between subtropical and temperate reef communities under climate change and specifically highlights the role of herbivores in releasing corals from competition with kelp under warming ocean regimes.

Water chemistry reveals a significant decline in coral calcification rates in the southern Red Sea

Experimental and field evidence support the assumption that global warming and ocean acidification is decreasing rates of calcification in the oceans. Local measurements of coral growth rates in reefs from various locations have suggested a decline of ~6–10% per decade since the late 1990's. Here, by measuring open water strontium-to-alkalinity ratios along the Red Sea, we show that the net contribution of hermatypic corals to the CaCO3 budget of the southern and central Red Sea declined by ~100% between 1998 and 2015 and remained low between 2015 and 2018. Measured differences in total alkalinity of the Red Sea surface water indicate a 26 ± 16% decline in total CaCO3 deposition rates along the basin. These findings suggest that coral reefs of the southern Red Sea are under severe stress and demonstrate the strength of geochemical measurements as cost-effective indicators for calcification trends on regional scales.

Mortality, growth and regeneration following fragmentation of reef-forming corals under thermal stress

Storms inflict damage to corals resulting in fragments that have the potential to regenerate thus contributing to the asexual reproduction of the parental colony. Extreme climatic events like these are predicted to increase in the future due to ocean warming, which is also the primary cause of coral reef bleaching and consequent coral mortality in the tropical and subtropical seas. This way it is urgent to investigate the differential effect of warming over post-fragmentation and regeneration processes among the scleractinian hermatypic coral species. This study investigated the mortality, growth and regeneration capacity of nine reef-forming coral species of the Indo-Pacific. Fragments were exposed to 26 °C, 30 °C, and 32 °C for 60 days. Half of these fragments was inflicted with one injury and the other half was used as control. Mortality, partial mortality, bleaching level, growth and regeneration of artificial injuries were assessed. Mortality increased with temperature, reaching 100% for most species after 60 days, at 32 °C, but Psammocora contigua which showed remarkably lower mortality (40%) and all coral fragments of Turbinaria reniformis and Galaxea fascicularis survived the experiment. Partial mortality was lowest for P. contigua, T. reniformis, and G. fascicularis even at 32 °C. These three coral species were also the most resistant to bleaching. Growth rates decreased with temperature, with the exception of G. fascicularis that maintained similar growth rates at 26 °C and 30 °C. Regeneration rates generally increased with temperature. It was concluded that P. contigua, T. reniformis, and G. fascicularis fragments show higher capacity to withstand higher temperatures.

Uncertainty and variability of extension rate, density and calcification rate of a hermatypic coral (Orbicella faveolata)

Skeleton growth variables of hermatypic corals, such as extension rate, density and calcification rate, are widely used to study coral response to environmental stressors, establish chronological age models and reconstruct the evolution of key climate variables. In this work, we addressed methodological aspects of the measurement of coral growth variables and the implications of their variability. A core of Orbicella faveolata was collected from the Puerto Morelos coral reef, in the Mexican Caribbean, and we measured and analysed 10 parallel transects of a core slab, covering 30 years. Density calibration was performed by measuring a high-quality and well-characterised wedge of Tridacna maxima, and the interval of interest was adjusted to the measured coral optical densities. The measurement uncertainties of extension rate, density and calcification rate were 0.011%, 1.1% and 1.6%, respectively. However, for density and calcification rate, overall variability was 29% and 33%, respectively, of which about half was attributed to intra-band growth variability. The intra-band variability of extension rate was only 0.68%, indicating the suitability of extension rate as a precise environmental proxy. These results likely differ by coral species, environments and experimental conditions, such as the exact location of the core within the colony and the method used to determine density. Uncertainties of coral growth variables should be carefully considered when reconstructing past environmental conditions.

Critical Information Gaps Impeding Understanding of the Role of Larval Connectivity Among Coral Reef Islands in an Era of Global Change

Populations of marine organisms on coral reef islands (CRI) are connected in space and time by seawater that transports propagules of plants, animals, and algae. Yet, despite this reality, it is often assumed that routine replenishment of populations of marine organisms on CRI is supported by locally-sourced propagules (hereafter, larvae). Following large disturbances, however, distantly-sourced larvae from less disturbed CRI within a regional meta-population are likely to be important for local population recovery, but evaluating the roles of locally- versus distantly- sourced larvae remains difficult. While larval sources are relatively well known for many fishes, they remain virtually unknown for most taxa, particularly those associated with the benthos, including hermatypic corals. We make the case that CRI provide natural laboratories in which studies of connectivity can enhance understanding of community dynamics under future disturbance regimes, especially where ongoing changes have created novel systems that are functioning in ways differing from the recent past. However, this potential cannot be realized due to the limited breadth, detail, and spatio-temporal concordance of exiting research. Targeted research on the role of connectivity in mediating ecosystem resilience of CRI is required to understand how populations of marine organisms will change in a future affected by large-scale disturbances of anthropogenic origin. Using the coral reefs of Mo’orea (French Polynesia), Okinawa (Japan), and St. John (US Virgin Islands) as examples, we describe the data required to achieve this objective, and discuss why provision of these data will require new modes of multidisciplinary and collaborative research.

Spongivory by Fishes on Southwestern Atlantic Coral Reefs: No Evidence of Top-Down Control on Sponge Assemblages

Predator-prey dynamics can affect assemblage structure and ecosystem processes representing a central theory in ecology. In coral reef ecosystems, recent evidences have suggested that sponge assemblages in regions with high diversity, like the Caribbean, are controlled by reef fishes (i.e. top-down control); however, this has been poorly studied in low diversity coral reefs. This study investigated the influence of fish predators on sponge assemblage structure in South Atlantic coral reefs, systems with high endemism and relatively low hermatypic coral diversity. We investigates (i) whether sponge cover is negatively correlated to spongivorous fish density, (ii) potential spongivory effects on competitive interactions between sponges and hermatypic corals and (iii) foraging preferences of spongivorous fishes. Benthic cover and spongivorous fish density were assessed by photo samplingt and visual census, respectively. We did not observe a negative correlation of the total density of sponge fish with total sponge cover . However, a significant negative correlation between density of fish species Pomacanthus arcuatus and cover of sponge species Scopalina ruetzleri was found. Spongivorous fish consumed preferentially the sponges Desmapsamma anchorata, Niphates erecta, Aplysina cauliformis and Scopalina ruetzleri, the first two species considered palatable and the second two with chemically defense mechanism. An increase to angelfish density was not related with the number of coral-sponge encounters. Thus, the effects of spongivorous fishes on sponges cover and competitive interactions with hermatypic corals is weaker in Southwestern Atlantic than previously reported in Caribbean coral reefs. We discuss how local human impacts (e.g. fishing and nutrients input) can influence the observed patterns.

Neurotransmitters in hermatypic coral, Acropora spp., and its contribution to synchronous spawning during reproductive event

Synchronous spawning as mass reproduction is well known to occur in many hermatypic corals, which is one of the mysterious life birth events. However, its contributing mechanism has not yet been clarified. This study placed focus on elucidating a neurotransmitter as endocrine signals that contribute to the synchronous spawning. First, the determination method of the neurotransmitters in coral was established by LC/MS in the selective ion mode together with a solid phase extraction method. As a result, the similar contents of the neurotransmitters for dopamine (DA), adrenaline (AD) and noradrenaline (NR) were detected in both the hermatypic corals of Acropora intermedia and Acropora digitifera. More interestingly, these neurotransmitters increased through the reproductive event during the synchronous spawning of A. intermedia, particularly, remarkable changes in the NR and DA were observed. In addition, hydrogen peroxide is known as the spawning stimulant and the metabolic by-product of the neurotransmitters, which was exposed to A. digitifera, then the neurotransmitters increased as well as those of the synchronization of spawning. All of the results suggested that the neurotransmitters contribute to the synchronous spawning in the hermatypic corals.

Continuous recordings of the coral bleaching process on Sesoko Island, Okinawa, Japan, over about 50 days using an underwater camera equipped with a lens wiper

The colours of the hermatypic corals Porites sp. and Acropora cytherea at Sesoko Island, Okinawa, Japan, were photographed continuously, from 19 July to 6 September 2016, by an underwater camera equipped with a lens wiper. The average seawater temperature during the study period was 29.9 °C. The daily average seawater temperature (DAST) was >30.0 °C until 23 August 2016, and a maximum value of 31.2 °C was recorded on 2 August 2016. Red, green, and blue (RGB) values of these corals were analysed based on photographs taken at 14:00. The RGB values of Porites sp. were stable throughout the observation period, while those of A. cytherea gradually increased (i.e. moved toward the “white” end of the spectrum) until the beginning of September. The present study demonstrated the usefulness of RGB analysis of photographs taken by an underwater camera equipped with a lens wiper for monitoring coral beaching.

First report of bioaccumulation and bioconcentration of aliphatic hydrocarbons (AHs) and persistent organic pollutants (PAHs, PCBs and PCNs) and their effects on alcyonacea and scleractinian corals and their endosymbiotic algae from the Persian Gulf, Iran: Inter and intra-species differences

The coral reefs of the Persian Gulf are the most diverse systems of life in the marine environment of the Middle East. Unfortunately, they are highly threatened by local and global stressors, particularly oil pollutants. This is the first quantitative and qualitative study aimed at assessing the concentration and sources of n-alkanes and POPs (PAHs, PCBs and PCNs) in coral tissues, symbiotic algae (zooxanthellae), reef sediments and seawaters in coral reefs of Lark and Kharg in the Persian Gulf, Iran. This work was conducted on eight species of six genera and three families of hard corals and one family of soft coral. A significant variation in the concentration of ∑30n-alkanes and POPs (∑40PAHs, ∑22PCBs and 20PCNs) was found in the decreasing order: zooxanthellae > coral tissue > skeleton > reef sediment > seawater. The bioaccumulation of these compounds was 2-times higher in ahermatypic than in hermatypic corals, among which significant variations were observed in both sites. In Kharg, Porites lutea had the highest mean concentration of ∑30n-alkanes and ∑40PAHs in soft tissue, whereas the lowest values were in Platygyra daedalea. A contrasting trend was documented for ∑22PCBs and 20PCNs, with the highest level reported in soft tissue of P. daedalea and the lowest in P. lutea at Kharg. Compositional pattern of AHs and PAHs demonstrated the predominance of LMW-PAHs and n-alkanes. In skeleton and reef sediments, tetra, penta and tri-CBs were the most abundant PCBs congeners followed by di-CB > hexa-CB > hepta-CB > octa-CB,whiletri-CB > di-CB > tetra-CB > penta-CB > hexa-CB > hepta-CB > octa-CB was observed for soft tissue, zooxanthellae and seawater. The results of RAD test indicated significantly negative correlation between total concentration of these compounds with zooxanthellae density, the chlorophyll-a and C2 in corals at both reefs. This is the first report on levels, health assessment and source apportionments of POPs in zooxanthellae and a first step in the implementation of specific coral reef management measures.

Preliminary Multivariate Comparison of Coral Assemblages on Carbonate Banks in the Western Gulf of Mexico

Hermatypic corals flourished on reefs in the Gulf of Mexico (GOM) in the late Pleistocene and early Holocene. Today, many of these relict reefs are mesophotic banks that have unique coral assemblages and provide critical habitat; however, the South Texas Banks (STB) lack quantitative surveys. Therefore, we used a remotely operated vehicle to conduct quantitative surveys of 5 banks: Baker, Aransas, Dream, Blackfish Ridge, and Harte. Coral communities, based on estimated coral densities (colonies/m2), significantly differed among banks for terraces, slopes, and overall (combined terrace and slope) communities for most banks examined. Within banks, terrace and slope communities significantly differed for all banks except Harte. Sea whips were the most abundant group on slopes and terraces of most banks and frequently contributed >50% to community similarities and dissimilarities, whereas sea fans and Antipathes frequently contributed >20%. Total coral abundance was twice as high and sea fans were 7 times more abundant on terraces than slopes. Among—bank differences in coral communities were highly correlated to geographic and geomorphic features, especially to bank area, rugosity, longitude, and number of site components. The drivers of these differences, their effects on ecosystem diversity and function, and the connectivity pathways within and among STB and other GOM banks require further investigation. Nevertheless, the observed diversity in community structure within and among banks should be considered in the development of monitoring, conservation, and management plans of these critical habitats.