Sea Fan Research Articles

New taxa and revisionary systematics of alcyonacean octocorals from the Pacific coast of North America (Cnidaria, Anthozoa)

A taxonomic assessment of four species of octocorals from the northeastern Pacific Ocean (British Columbia to California) is provided. Included here are a new species of clavulariid stolonifieran Cryptophyton, a new species of the nephtheid soft coral Gersemia, an undetermined species of soft coral in the genus Alcyonium that has been referred in the literature by several other names, and a new genus is named for a plexaurid sea fan originally described in the Indo-Pacific genus Euplexaura. Discussions are included that compare the species to related taxa, or provide revisionary assessments.

Patterns of egg deposition and egg development in the catsharks Poroderma pantherinum and Haploblepharus pictus

Patterns of egg deposition and rates of egg development were examined for two endemic South African scyliorhinid shark species: Poroderma pantherinum, the leopard catshark, and Haploblepharus pictus, the dark shy shark. P. pantherinum laid their eggs at an average depth of 18.95 m (min: 7.4 m; max: : 26.8 m) preferentially attaching their eggs singly onto sea fans Leptogorgia palma, Eunicella papillosa and Eunicella tricoronata. H. pictus laid their eggs at an average depth 3m(min: 1m; max: 30.7 m) and attached their eggs, predominantly in pairs, to the seaweed Bifurcariopis capensis. The average temperature at which eggs were found were similar (15°C) and eggs were laid year-round. Embryo development was observed in the laboratory under constant controlled environmental conditions of 14 and 17°C. Embryo length-age relationships were linear for both species and there were significant differences in growth rate at the two temperatures. For P. pantherinum average growth rate was 0.37 mm/day at 14°C and 0.79 mm/day at 17°C. The average incubation period was 266 days at 14°C and 125 days at 17°C. Embryos thus grew two times faster and development time was 53% shorter when the temperature was raised by only 3°C. For H. pictus, the average growth rate was 0.49 mm/day at 14°C and 0.78 mm/day at 17°C. The incubation period was 242 days at 14°C and 190 days at 17°C. The embryos thus grew 1.6 times faster and incubation time was 21.5% shorter when temperature was raised by only 3°C.

Patterns of Egg Deposition and Egg Development in the CatsharksPoroderma pantherinumandHaploblepharus pictus

Patterns of egg deposition and rates of egg development were examined for two endemic South African scyliorhinid shark species: Poroderma pantherinum, the leopard catshark, and Haploblepharus pictus, the dark shy shark. P. pantherinum laid their eggs at an average depth of 18.95 m (min: 7.4 m; max: : 26.8 m) preferentially attaching their eggs singly onto sea fans Leptogorgia palma, Eunicella papillosa and Eunicella tricoronata. H. pictus laid their eggs at an average depth 3 m (min: 1 m; max: 30.7 m) and attached their eggs, predominantly in pairs, to the seaweed Bifurcariopis capensis. The average temperature at which eggs were found were similar (15°C) and eggs were laid year-round. Embryo development was observed in the laboratory under constant controlled environmental conditions of 14 and 17°C. Embryo length-age relationships were linear for both species and there were significant differences in growth rate at the two temperatures. For P. pantherinum average growth rate was 0.37 mm/day at 14°C and 0.79 mm/day at 17°C. The average incubation period was 266 days at 14°C and 125 days at 17°C. Embryos thus grew two times faster and development time was 53% shorter when the temperature was raised by only 3°C. For H. pictus, the average growth rate was 0.49 mm/day at 14°C and 0.78 mm/day at 17°C. The incubation period was 242 days at 14°C and 190 days at 17°C. The embryos thus grew 1.6 times faster and incubation time was 21.5% shorter when temperature was raised by only 3°C.

Diet and consumption rates of common dolphinfish, Coryphaena hippurus, in the eastern Arabian Sea

Summary The aim of the study was to identify the diet composition, feeding preferences, size and sex related diet changes, and to calculate the consumption rates of common dolphinfish, Coryphaena hippurus, in the eastern Arabian Sea. Fish were caught using longline gear during the years 2006–2009. Stomachs of 238 specimens with fork lengths ranging from 324 to 1250 mm were analysed; 72 (30.25%) of the stomachs were empty. Epipelagic finfishes were the predominant prey followed by cephalopods and crustaceans. Occurrence of items such as sargassum, sea fans, corals, plastics and pieces of wood in the stomachs indicate an opportunistic and voracious feeding nature. Flyingfishes (family Exocoetidae), especially Exocoetus monocirrhus (%IRI 16.92), dominated the diet. Unidentified filefishes (family Monacanthidae), Sthenoteuthis oualaniensis, Euthynnus affinis, Cheilopogon furcatus and Cubiceps pauciradiatus were other important food items. The diet varied between sexes and different size classes. Juveniles and adults (size classes 115 cm) fed preferentially on cephalopods. Food consumption rate was higher in females (6.37% BW day−1) compared to males (4.04% BW day−1), and increased with their increase in size up to 75–95 cm length classes, thereafter decreasing. The daily meal and daily ration was 332.63 g day−1 and 5.25% BW day−1, respectively, and average annual food consumption was 121.41 kg.

Special issue Oceans and Humans Health: the ecology of marine opportunists.

Opportunistic marine pathogens, like opportunistic terrestrial pathogens, are ubiquitous in the environment (waters, sediments, and organisms) and only cause disease in immune-compromised or stressed hosts. In this review, we discuss four host-pathogen interactions within the marine environment that are typically considered opportunistic: sea fan coral-fungus, eelgrass-Labyrinthula zosterae, sea fan-Labyrinthulomycetes, and hard clam-Quahog Parasite Unknown with particular focus on disease ecology, parasite pathology, host response, and known associated environmental conditions. Disease is a natural part of all ecosystems; however, in some cases, a shift in the balance between the host, pathogen, and the environment may lead to epizootics in natural or cultured populations. In marine systems, host-microbe interactions are less understood than their terrestrial counterparts. The biological and physical changes to the world's oceans, coupled with other anthropogenic influences, will likely lead to more opportunistic diseases in the marine environment.

Immune response of the Caribbean sea fan, Gorgonia ventalina, exposed to an Aplanochytrium parasite as revealed by transcriptome sequencing.

Coral reef communities are undergoing marked declines due to a variety of stressors including disease. The sea fan coral, Gorgonia ventalina, is a tractable study system to investigate mechanisms of immunity to a naturally occurring pathogen. Functional studies in Gorgonia ventalina immunity indicate that several key pathways and cellular components are involved in response to natural microbial invaders, although to date the functional and regulatory pathways remain largely un-described. This study used short-read sequencing (Illumina GAIIx) to identify genes involved in the response of G. ventalina to a naturally occurring Aplanochytrium spp. parasite. De novo assembly of the G. ventalina transcriptome yielded 90,230 contigs of which 40,142 were annotated. RNA-Seq analysis revealed 210 differentially expressed genes in sea fans exposed to the Aplanochytrium parasite. Differentially expressed genes involved in immunity include pattern recognition molecules, anti-microbial peptides, and genes involved in wound repair and reactive oxygen species formation. Gene enrichment analysis indicated eight biological processes were enriched representing 36 genes, largely involved with protein translation and energy production. This is the first report using high-throughput sequencing to characterize the host response of a coral to a natural pathogen. Furthermore, we have generated the first transcriptome for a soft (octocoral or non-scleractinian) coral species. Expression analysis revealed genes important in invertebrate innate immune pathways, as well as those whose role is previously un-described in cnidarians. This resource will be valuable in characterizing G. ventalina immune response to infection and co-infection of pathogens in the context of environmental change.

Bilateral proliferative retinopathy as the initial presentation of chronic myeloid leukemia

The authors report a rare case of a 48-year-old male with chronic myeloid leukemia (CML) who initially presented with a bilateral proliferative retinopathy. The patient complained of recent visual loss and floaters in both eyes (BE). Ophthalmologic evaluation revealed a best corrected visual acuity (BCVA) of 20/50 in the right eye and 20/200 in the left eye (LE). Fundoscopy showed the presence of bilateral peripheral capillary dropout with multiple retinal sea fan neovascularisations, which were confirmed on fluorescein angiography. Full blood count revealed hyperleukocytosis, thrombocytosis, anemia, and hyperuricemia. Bone marrow aspiration and biopsy showed the reciprocal chromosomal translocation t (9;22), diagnostic of CML. The patient was started on hydroxyurea, allopurinol and imatinib mesylate. He received bilateral panretinal laser photocoagulation and a vitrectomy was performed in the LE. The patient has been in complete hematologic, cytogenetic, and major molecular remission while on imatinib and his BCVA is 20/25 in BE.

When aspergillosis hits the fan: Disease transmission and fungal biomass in diseased versus healthy sea fans (Gorgonia ventalina)

Abstract Sea fan aspergillosis, first reported in the Caribbean in the 1990s, is one of the best-characterized coral diseases. The disease is named after Aspergillus sydowii , which was proposed as the sole pathogen. Here, inoculation of healthy fans in aquaria with A. sydowii failed to induce purpling and tissue necrosis, the characteristic signs of aspergillosis. Grafting experiments in situ , using diseased and healthy tissues, failed to induce permanent purpling in most cases, suggesting that fans have developed resistance to aspergillosis. The temporary purpling is likely a non-self-recognition response and not an exclusive criterion to diagnose aspergillosis. For the first time, we quantified fungal biomass in fans demonstrating that ergosterol concentration in healthy tissues was generally higher than that in the diseased tissues, contrary to our expectations for a fungal-induced disease. These results suggest that there are still considerable gaps in our understanding of aspergillosis, coral-associated fungal communities and coral non-self-recognition responses.

Spatial variability of disease incidence and mortality in the sea fan <i>Gorgonia ventalina</i> in Puerto Rico (Alcyonacea: Goorgoniidae)

Populations of the common sea fan (Gorgonia ventalina) were decimated by an aspergillosis outbreak throughout the Caribbean two decades ago. Since then, aspergillosis has been considered as the principal cause of mortality in sea fans. However, prevalence and presumably incidence of this disease have been declining in the Caribbean since the mid 1990s. Incidence indicates new cases of disease in previously healthy colonies, while prevalence indicates percent of diseased colonies at a given sample. Most coral disease studies use prevalence rather than incidence to assess the temporal dynamics of diseases. Nevertheless, conclusions based only on prevalence should be handled carefully to avoid misinterpretation. This study was carried out at six reefs in Eastern Puerto Rico. We monitored a total of 448 colonies to (1) obtain estimates of incidence and prevalence of disease and other types of lesions, and (2) to determine causes of sea fan mortality plus their spatial and temporal variation. Three transects (10x1m) were haphazardly placed at each study site. At each transect, every colony was numbered and photographed and its height measured to the nearest cm. Transects were monitored at six months intervals and health status of the colonies was recorded. Also, the colonies were divided into height classes (small, medium and large) for incidence, prevalence and mortality analyses. Incidence and prevalence of disease were low in all reefs, suggesting that disease currently plays a minor role in the regulation of sea fans populations. Detachment was the main cause of mortality, and size structure data suggest that recruitment may compensate for mortality rates in two of the reefs. Spatial differences in size structure and density may be related to environmental and physical characteristics at the reef scale that allow sea fans to reach a safe colony size.

Isolation of potential fungal pathogens in gorgonian corals at the Tropical Eastern Pacific

A major environmental problem in the ocean is the alarming increase in diseases affecting diverse marine organisms including corals. Environmental factors such as the rising seawater temperatures and terrestrial microbial input to the ocean have contributed to the increase in dis- eased organisms. We isolated and identified the fungal agents that may be leading to a disease in the Pacific sea fan Pacifigorgia eximia (Gorgoniidae, Octocorallia) in the Tropical Eastern Pacific. We isolated thirteen fungal gen- era in healthy and diseased colonies including Aspergillus sydowii. Aspergillus has been previously identified as responsible for the mortality of gorgonian corals in the Caribbean. This disease was observed in the Eastern Pacific affecting a completely different set of species nearly 30 years after the Caribbean outbreak, which concur with rising seawater temperatures and thermal anomalies that have been observed in the last 4 years.

Friend or foe: the association of Labyrinthulomycetes with the Caribbean sea fan Gorgonia ventalina

A new syndrome in sea fans Gorgonia ventalina consisting of multifocal purple spots (MFPS) has been observed in the Caribbean Sea. Surveys of MFPS on sea fans were conducted from 2006 to 2010 at a shallow and deep site in La Parguera, Puerto Rico (PR). At the shallow site, MFPS increased between 2006 and 2010 (site average ranged from 8 to 23%), with differences found at depths over time using an analysis of covariance (ANCOVA, p < 0.0001). As a potential causative agent we examined a Labyrinthulomycota-like ovoid parasite that was observed to be abundant in MFPS lesions in light micrographs. Labyrinhylomycetes were successfully isolated, cultured and characterized in sea fans from Florida and PR. Sequence information obtained from the small subunit (SSU) rRNA gene indicated that Labyrinthulomycetes in most sea fans (healthy and MFPS sea fans from Florida; MFPS from PR) and the cultured microorganism are in the genus Aplanochytrium, although some healthy sea fans from PR contained members of the genus Thraustochytrium. Both genera fall within the family Thraustochytriidae. Histology confirmed observations of thraustochytrids within apparently healthy and MFPS sea fans from PR, and specific staining indicated a host melanization response only in colonies containing Labyrinthulomycetes or fungal infections. Growth trials indicate that the temperature-growth optima for the cultured microorganism is ~30°C. In inoculation experiments, the cultured Aplanochytrium did not induce purple spots, and histology revealed that many of the apparently healthy recipients contained Labyrinthulomycetes prior to inoculation. Taken together, these results indicate that the Labyrinthulomycetes associated with sea fans is likely an opportunistic pathogen. Further studies are needed to understand the pathogenesis of this microorganism in sea fans and its relationship with MFPS.

Impact of hot fluid advection on hydrocarbon gas production and seepage in mud volcano sediments of thick Cenozoic deltas

Hydrocarbon seeps are ubiquitous at gas-prone Cenozoic deltas such as the Nile Deep Sea Fan (NDSF22NDSF:Nile Deep Sea Fan.) where seepage into the bottom water has been observed at several mud volcanoes (MVs33MV: mud volcano.) including North Alex MV (NAMV44NAMV: North Alex mud volcano.). Here we investigated the sources of hydrocarbon gases and sedimentary organic matter together with biomarkers of microbial activity at four locations of NAMV to constrain how venting at the seafloor relates to the generation of hydrocarbon gases in deeper sediments. At the centre, high upward flux of hot (70°C) hydrocarbon-rich fluids is indicated by an absence of biomarkers of Anaerobic Oxidation of Methane (AOM) and nearly constant methane (CH4) concentration depth-profile. The presence of lipids of incompatible thermal maturities points to mixing between early-mature petroleum and immature organic matter, indicating that shallow mud has been mobilized by the influx of deep-sourced hydrocarbon-rich fluids. Methane is enriched in the heavier isotopes, with values of δ13C∼−46.6‰VPDB and δD ∼−228‰VSMOW, and is associated with high amounts of heavier homologues (C2+) suggesting a co-genetic origin with the petroleum.On the contrary at the periphery, a lower but sustained CH4 flux is indicated by deeper sulphate–methane transition zones and the presence of 13C-depleted biomarkers of AOM, consistent with predominantly immature organic matter. Values of δ13C-CH4∼−60‰VPDB and decreased concentrations of 13C-enriched C2+ are typical of mixed microbial CH4 and biodegraded thermogenic gas from Plio-Pleistocene reservoirs of the region. The maturity of gas condensate migrated from pre-Miocene sources into Miocene reservoirs of the Western NDSF is higher than that of the gas vented at the centre of NAMV, supporting the hypothesis that it is rather released from the degradation of oil in Neogene reservoirs. Combined with the finding of hot pore water and petroleum at the centre, our results suggest that clay mineral dehydration of Neogene sediments, which takes place posterior to reservoir filling, may contribute to intense gas generation at high sedimentation rate deltas.

Late Quaternary deep-sea sedimentation in the western Black Sea: New insights from recent coring and seismic data in the deep basin

The Danube River Basin–Black Sea area represents a unique natural laboratory for studying the interplay between lithosphere and surface as well as source to sink relationships and their impact on global change. This paper addresses some information on the “active sink” of the system; i.e. the Danube deep sea fan and the Black Sea basin. The present study focuses on the distal sedimentary processes and the evolution of sedimentation since the Last Glacial Maximum. This is investigated through recently acquired long piston coring and shallow seismic data recovered at the boundary of influence of the distal part of the Danube turbidite system (to the north-west) and the Turkish margin (to the south). This dataset provides a good record of the recent changes in the sedimentary supply and climato-eustasy in the Black Sea region during the last 25ka. This study demonstrates that the deep basin deposits bear the record of the Late Quaternary paleoenvironmental changes and that the western Black Sea constitutes an asymmetric subsident basin bordered by a northern passive margin with confined, mid-size, mud-rich turbidite systems mainly controlled by sea-level, and a southern turbidite ramp margin, tectonically active.

Gulf spill two years out

Summary Two years on, the national spotlight seems to have turned away from the Gulf oil spill, but a massive assessment of the environmental impacts is quietly under way. As Cyrus Martin reports, several recent observations, and a study of deepwater coral communities, suggest we may not be out of the woods yet.

Development of a new standardised method for sustainable monitoring of the vulnerable pink sea fan Eunicella verrucosa

The aim of this survey was to test a standardised method to follow the demographic evolution of a dense aggregative ‘forest’ population of the temperate gorgonian Eunicella verrucosa (Octocorallia, Gorgoniidae) using in situ photographic recordings. Distribution, density, growth and demographic evolution of the colonies was compared along two parallel transects. Computer treatment allowed the estimation of the total branch fan surface area, and the individual growth of tagged colonies was determined by measuring the increase in this surface area, using consecutive photographs taken at two-year intervals. To integrate the potential bias of branch overlapping, we proposed a correction factor between the in situ photographic surface area and the surface area of the gorgonian calculated from ex situ photographic surface area with all branches deployed. The surface-frequency distribution of colonies was converted to estimated-age-frequency distribution using an estimated growth curve based on the net growth rate. The technique used revealed significant differences in population structure and the dynamics of gorgonian colonies, as the two transects appeared to be influenced by different environmental conditions. The recruitment also seemed to vary according to year and transect, resulting in different densities. Our work showed clear results in characterising the variations of gorgonian demographic evolution at a small spatial scale; thus, it is assumed that this method could be a sustainable tool for coastal environmental managers.

The spatial pattern and drainage cell characteristics of a pockmark field, Nile Deep Sea Fan

Over 25,300 seabed pockmarks were mapped from the Rosetta Channel region of the Western Nile Deep Sea Fan (NDSF) using concurrent High Resolution 2D, Chirp profiler and multibeam bathymetry data which spans the Holocene–Pleistocene period. Within the region, a pockmark field containing >13,800 pockmarks was analysed using spatial statistics to determine the distribution of pockmarks within the field. Pockmarks within the field are small (∼16 m diameter), shallow (∼0.5 m deep) circular depressions which formed within the last ∼ 6500 years. The fluid source for the field is identified as an accumulation/generation of gas beneath a hemipelagic seal c. 20–40 ms beneath the seabed. The position of the pockmarks is shown to be unrelated to the depth to the fluid source and an irregular high amplitude acoustic anomaly which is tentatively interpreted as a possible carbonate precipitate of biogenic microbial activity. Statistical spatial analysis of the field confirms the distribution of pockmarks is not random. An exclusion zone surrounding each individual pockmark is identified. The exclusion zone is a unique minimum radius around each pockmark which is not penetrated by any other pockmark. The exclusion zone works in unison with Self-Organised Criticality (SOC) in determining the spatial distribution of pockmarks within the field. The exclusion zone is interpreted as a pockmark “drainage cell”. A conceptual model for a pockmark drainage cell is proposed whereby pockmark formation dissipates a radius/area of fluid and overpressure, thereby preventing the formation of another pockmark within that cell. Consequently, pockmarks are observed to separate or produce anti-clustering tendencies within the field.

Evidence for fluid migration following pockmark formation: Examples from the Nile Deep Sea Fan

A large number of pockmarks have been identified in the Rosetta Region of the Western Nile Deep Sea Fan. Co-located high resolution 2D and Chirp datasets have been used to identify seabed and buried pockmarks which are interpreted to span the Holocene to Pleistocene period. The pockmarks range in size and stratigraphic position from large buried pockmarks to small unit seabed pockmarks. Clusters of small unit pockmarks are stratigraphically positioned above the centre of large buried Pleistocene pockmarks and are used to infer: 1) rejuvenation of the larger pockmark conduit once burial has occurred, and 2) a change in the frequency and magnitude of pockmark formation events.

Quaternary denudation of southern Fennoscandia – evidence from the marine realm

Throughout the last 1.1 million years repeated glaciations have modified the southern Fennoscandian landscape and the neighbouring continental shelf into their present form. The glacigenic erosion products derived from the Fennoscandian landmasses were transported to the northern North Sea and the SE Nordic Seas continental margin. The prominent sub‐marine Norwegian Channel trough, along the south coast of Norway, was the main transport route for the erosion products between 1.1 and 0.0 Ma. Most of these erosion products were deposited in the North Sea Fan, which reaches a maximum thickness of 1500 m and has nearly 40 000 km3 of sediments. About 90% of the North Sea Fan sediments have been deposited during the last 500 000 years, in a time period when fast‐moving ice streams occupied the Norwegian Channel during each glacial stage. Back‐stripping the sediment volumes in the northern North Sea and SE Nordic Seas sink areas, including the North Sea Fan, to their assumed Fennoscandian source area gives an average vertical erosion of 164 m for the 1.1–0.0 Ma time period. The average 1.1–0.0 Ma erosion rate in the Fennoscandian source area is estimated to be 0.15 mm a−1. We suggest, however, that large variations in erosion rates have existed through time and that the most intense Fennoscandian landscape denudation occurred during the time period of repeated shelf edge ice advances, namely from Marine Isotope Stage 12 (c. 0.5 Ma) onwards.

An in vivo morphologic comparison of retinal neovascularization in sickle cell and diabetic retinopathy.

To analyze the in vivo morphology of the sea fan in proliferative sickle cell retinopathy and compare it with the neovascularization in proliferative diabetic retinopathy. Brief case report of spectral-domain optical coherence tomography imaging of a sea fan in a patient with sickle cell anemia and newly diagnosed proliferative sickle cell retinopathy, and morphologic comparison with spectral-domain optical coherence tomography imaging of a neovascular membrane in a diabetic patient with proliferative diabetic retinopathy. Spectral-domain optical coherence tomography imaging revealed that the sea fan is a thicker caliber preretinal fibrovascular membrane involving primarily the retinal nerve fiber and ganglion cell layers. The diabetic membrane has more vitreous adhesions, and it is more closely intertwined with the retina, involving all the retinal layers down to the outer plexiform layer. Spectral-domain optical coherence tomography imaging identified important in vivo morphologic differences between neovascularization in proliferative sickle cell retinopathy and proliferative diabetic retinopathy. These differences were consistent with previous histological studies and may explain the increased risk of tractional retinal detachment in patients with diabetes.

Bioactive Peptides from Epibiotic Pseudoalteromonas Strain P1

An epibiotic bacterial strain designated as P1 with characteristic colony morphology was isolated from five random samplings of the sea fan coral Junceella juncea (Pallas, 1766). Phylogenetic identification based on comparative sequence analysis of 16Ss rRNA gene indicated that the stain P1 fell under the genera Pseudoalteromonas. In the initial screening using agar overlay method the Pseudoalteromonas strain P1 was found to exhibit broad spectral activity inhibiting 7 out of 10 test strains. A highest zone of 25mm was noted against two bacterial strains, B. subtilis and S. typhi. The strain P1 formed a distinct biofilm layer over the marine broth (air-liquid interface) in static culture at room temperature. The active component was also found to be adsorbed on the biofilm layer. Protease digestion of the crude extract resulted in the loss of activity indicating the protenacious nature of the active molecules. Bioassay guided purification using anion exchange chromatography and RP-HPLC yielded a molecule with antimicrobial activity. Mass spectrophotometry analysis has shown that this molecule has a mass of 1115Da. In cation exchange purification, two molecules of masses 1520 and 1542Da were found in the active fraction. Morphological and physiological characterization of the Pseudolateromonas strain P1 shown it to be a pigmented, motile, catalase and oxidase positive rod. Studies regarding epibotic bacteria in Indian waters have been few. This study highlights the importance of epibiotic bacteria associated with corals as a potential source for the discovery of novel antimicrobial and other natural products.