Dead Coral Fragments Research Articles

Density and Distribution Pattern of Lola Snail (Trocus niloticus) in the Coastal Waters of Malaku Village, Central Maluku

The lola snail (Trochus niloticus) is a species of sea snail that has important economic value. This research aims to determine the density and distribution patterns of lola snails in the coastal waters of Malaku Village, Central Maluku. Sampling used a stratified random sampling method with line transects, the research location was divided into 3 stations. Stations I and III have plank coral substrates and dead coral fragments, while station II has rocky substrates and coral flats. The results of the research found that the total number of lola snail individuals found at the research location was 110 individuals spread across 3 research stations. The maximum size of lola snails found was 99.41 mm in diameter and the minimum size found was 47.18 mm in diameter. The highest density of Lola snails at each research station was 0.08 ind/m2 and the lowest was 0.05 ind/m2. The distribution pattern of Lola snails at the research location is a clustered pattern.

Cover Picture and Issue Information

Journal of Animal EcologyVolume 91, Issue 11 p. 2151-2153 COVER PICTURE AND ISSUE INFORMATIONFree Access Cover Picture and Issue Information First published: 02 November 2022 https://doi.org/10.1111/1365-2656.13529AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract Cover image: Coral reef biodiversity is best supported through an assortment of microhabitat types, including coral species of differing morphologies, as well as dead coral. Interestingly, the greatest density and diversity of animals on coral reefs is found in coral rubble – broken dead coral fragments that scatter the seafloor. Stella et al. highlight this overlooked biodiversity in coral reefs across a range of microhabitats with links to water quality and reef fish biomass. See Pp. 2203–2219. Photo: Kennedy Wolfe. Volume91, Issue11November 2022Pages 2151-2153 RelatedInformation

RADIOCARBON DATING OF PRECIOUS CORALS OFF THE SOUTHWEST COAST OF KOCHI PREFECTURE, SOUTHWEST JAPAN

ABSTRACTRadiocarbon (14C) dating was performed for various types of precious coral colony fragments collected from the Ashizuri fishing field, around 100–200 m deep, off the southwest coast of Kochi Prefecture, Japan, to understand the historical background of one of the largest precious coral fishing fields in Japan. The 14C ages of the 55 specimens range from ~7500 years ago to the modern. Most of the measured samples were older than 1871, when fishing activities of precious corals began in Kochi Prefecture. These results suggest that most of the deaths of the precious coral colonies were due to natural causes, such as natural mortality, predation, or various forms of environmental degradation, and not strictly related to destructive fishing practices. Additionally, precious corals started inhabiting the study area at least ~7500 years ago, when the marine condition became similar to that of today after the Last Glacial Period. This study is the first to focus on the age of dead precious coral fragments and has revealed that they might be an important fossil resource that could lengthen the timespan of precious coral fishery. This additional time may enable us to establish reasonable and effective regulations for sustainable fishery.

Eunicida and Amphinomida polychaetes (Annelida) inhabiting dead coral fragments in the Chinchorro Bank Biosphere Reserve, Mexican Caribbean

ABSTRACT. Introduction: The polychaete fauna inhabiting Chinchorro Bank has been poorly studied and only 35 species have been previously reported. Objective: To examine the taxonomic composition of the Eunicida and Amphinomida associated to dead coral substrates from this coral reef atoll, a Biosphere Reserve located in the southern Mexican Caribbean. Methods: In April 2008, dead coral fragments of the genus Porites were manually collected by SCUBA diving at eight stations between 4-16.2 m depth. Results: A total of 714 individuals belonging to 17 genera and 48 species of the families Amphinomidae, Dorvilleidae, Eunicidae, Lumbrineridae, Oenonidae and Onuphidae were identified. Eunicidae was clearly the more diverse (29 species; 60.4 %) and abundant family (479 individuals; 67.1 %), while the Oenonidae and Onuphidae were represented by only one individual-species each. Thirty-eight species (79.2 %) were new records for Chinchorro Bank, of which 23 species (47.9 %) were newly reported for the Western Caribbean ecoregion. Conclusions: The polychaete fauna recorded showed that the Chinchorro Bank reef is a species-rich habitat that deserves further study; the 48 species from six families identified were similar or even greater than the number of species reported from dead coral environments of other Caribbean Sea regions.

Composition and diversity patterns of Eunicida and Amphinomida (Annelida) associated to dead coral in the Chinchorro Bank Biosphere Reserve, Caribbean Sea

AbstractThe present study is the first attempt to describe beta-diversity patterns in polychaetes of the Caribbean Sea, analysing depth changes in species composition of the Eunicida and Amphinomida inhabiting dead coral in Chinchorro Bank, southern Mexican Caribbean. In April 2008, dead coral fragments were collected by scuba diving in eight stations along two bathymetric gradients (4–9 m and 7–16.2 m depth); 755 individuals from 53 species of the families Amphinomidae, Dorvilleidae, Eunicidae, Lumbrineridae, Oenonidae and Onuphidae were identified. The highest number of species (32) and individuals (514) were found in the family Eunicidae. The Northern transect harboured 36 species, on average 18.75 ind. L−1, which decreased linearly with depth; the Central transect had 43 species, on average 19.01 ind. L−1, which increased at middle depths. The species inhabiting both these zones were moderately different (βsor = 0.603): 49.06% of the fauna occurred on both transects, but the components of beta-diversity, turnover and nestedness, displayed distinct patterns: in the Northern one replacement was the dominant factor (βsim = 0.3–1; βnes = 0–0.091), practically representing all faunal differences (βsor = 0.391–1); in the Central, dissimilarity due to nestedness increased (βnes = 0.031–0.829), mainly at the shallowest stations, but from 5 m depth, beta-diversity was almost completely explained by species replacement (βsim = 0.417–0.5; βnes = 0.031–0.318). Faunal differences were mostly related to higher abundances ofLysidice caribensis,Eunice goodeiandLumbrineris floridanain the Northern zone, andLumbrineris perkinsi,Nicidion obtusa,Lysidice caribensis,Lumbrineris floridana,Lysidice unicornisandEunice mutilatain the Central zone.

Intruder identity alters the response of territorial damselfish protecting algal farms

Herbivorous damselfish that cultivate algal farms frequently exhibit aggressive territorial behaviour to defend their investment from intruders, particularly against other herbivorous fish and invertebrates. On a coastal coral reef in New Caledonia, the response of the damselfish Hemiglyphidodon plagiometopon to intruders of varying type and level of threat to their algal farm was tested. Responses to live and dead coral fragments, carnivorous whelks, shells, and rocks varied from no response to biting and extrusion from farms. Damselfish elicited the strongest defensive response to the herbivorous sea urchin Echinometra mathaei, rapidly attacking the urchin by biting and lifting it from farms, before extruding it up to 3.5 m away. H. plagiometopon responded in a similar manner to dead urchins (no threat of herbivory) as to live urchins, but typically did not extrude them as far. Ultimately, damselfish responded to intruders in a manner largely consistent with the level of threat posed to their algal farm, with the similar response between live and dead urchins suggesting such strong defensive behaviours may be combination of ‘hard-wired’ and learned behaviours in reaction to the level of realised threat.

Species Inventory of Brittel Stars (Ophiuroidea) at Bilik Beach, Baluran National Park, East Java

The Brittle stars is a member of the Phylum Echinodermata that lives in habitats in the intertidal, subtidal, and deep sea zones. Brittle stars can be found in areas of coral reefs, sand, seagrass, macroalgae (seaweed), and dead coral fragments. One of the many intertidal areas of the brittle stars habitat is in the Bilik Beach, Baluran National Park. Ophiuroidea is important to be studied in the conservation area, Baluran National Park, because it is a natural conservation area that has native ecosystems and is managed with a zonation system and utilized for natural tourism, research, science and education purposes. This study aims to determine the type of brittle stars found on the Baluran National Park. The method used in this research is descriptive method with road sampling technique in the Bilik Beach area. The brittle stars species found and described are 8 species, namely Ophiomastix annulosa, Ophiocoma scolopendrina, O. brevipes, Ophioplocus imbricatus, Ophiolepis cardioplax, O. superba, Ophiarachna parvispina, and Macrophiothrix longipeda.

Correlation between pollution and decline of Scleractinian Cladocora caespitosa (Linnaeus, 1758) in the Gulf of Gabes.

During an expedition in 2014 in the Gulf of Gabes that aimed to evaluate the impact of the pollution of the phosphate industry on the marine environment, numerous dead coral fragments were retrieved from several stations along a 18 km long transect in front of the industry complex of Gabes. Detailed taxonomy of these coral fragments shows clearly that all fragments belong to the species Cladocora caespitosa (Linnaeus, 1758). Quantitative analysis of the coral fragments indicates a positive correlation with stations characterized by positive bathymetric anomalies. We suggest the presence of probable small-scaled (up to 4 m high) biogenic (palaeo-) build-ups composed mainly of coral colonies and bryozoans. Radiocarbon dating of three coral fragments show ages as old as 1897, 1985 and 1986 AD and suggests the presence of living C. caespitosa as close as 6 km to the phosphate treatment industry of Gabes at least until 1986 AD. This latter age coincides with the construction of the ammonium phosphate production plant, in 1979, in the Gulf of Gabes with an increase of the natural phosphate production. The higher impact of pollution on the marine environment in the inner part of the Gulf of Gabes likely induced the decline of C. caespitosa. This is well in agreement with enhanced siltation processes suggested by the sedimentary facies and grain-size analyses presently characterizing the Gulf of Gabes nowadays.

Non-colonial coral macro-borers as indicators of coral reef status in the south Pacific of Costa Rica

Coral reef status was surveyed in three south Pacific coral reefs of Costa Rica, one in Caño Island and two in Golfo Dulce, and the density, richness and distribution of non-colonial macro borers (> 1 mm) was determined in dead and live coral fragments from these reefs. Based upon traditional indicators of degradation such as high particulate suspended matter and low live coral cover, the reefs at Caño Island are in better condition than those at Golfo Dulce. Reef degradation in Golfo Dulce is mainly due to high loads of terrestrial sediments as a consequence of watersheds deforestation. In this study, 36 coral boring species are reported for the eastern Pacific. At the family level, there is high endemism (10%) and greater affinity with the Indo-Pacific (34%), as compared with the eastern Atlantic and Mediterranean (29%) and western Atlantic and Caribbean (27%). The dominant non-colonial macro boring families at the study reefs are mytilid bivalves, eunicid polychaetes and aspidosiphonid sipunculans, with the bivalves considered the main internal bioeroders due to their greater body size and abundances. The level of mortality of the coral colonies and the general level of reef degradation influenced the composition of non-colonial macro-borers. Diversity and total macro-borer density, especially aspidosiphonid density, is higher in corals with greates dead than live cover. In the healthiest coral colonies (less than 50% of partial mortality), mytilids domination, macro-borer diversity and total density, is higher in Golfo Dulce, where reefs are more degraded. In the most affected coral colonies (more than 50% dead), macro-borers total density, especially aspidosiphonids density, is higher, of the healthiest reef of this study, Platanillo. Bivalve relative abundance increases and sipunculan relative abundance decreases with increasing site degradation. In conclusion bioeroder variables can also be used as reef health indicators.

Evidence for the bioerosion of deep-water corals by echinoids in the Northeast Atlantic

In situ video observations of echinoids interacting with deep-sea coral are common in the deep-sea, but paradoxically the deep-sea literature is devoid of reports of bioerosion by extant echinoids. Here we present evidence of contemporary bioerosion of cold-water coral by four species of deep-sea echinoids, Gracilechinus elegans, Gracilechinus alexandri, Cidaris cidaris, and Araeosoma fenestratum, showing that they actively predate on the living framework of reef building corals, Lophelia pertusa and Madrepora oculata, in the NE Atlantic. Echinoid specimens were collected in six canyons located in the Bay of Biscay, France and two canyons on the north side of the Porcupine Bank and Goban Spur, Ireland. A total of 44 live specimens from the four taxa (9 of G. elegans, 4 of G. alexandri, 21 of C. cidaris and 10 of A. fenestratum) showed recent ingestion of the coral infrastructure. Upon dissection, live coral skeleton was observed encased in a thick mucus layer within the gastrointestinal tract of G. elegans and G. alexandri while both live and dead coral fragments were found in C. cidaris and A. fenestratum. Echinoid bioerosion limits the growth of shallow-water reefs. Our observations suggest that echinoids may also play an important role in the ecology of deep-water coral reefs.

Cryptofaunal Polychaetes from Oceanic and Continental Reefs in Venezuela

Here we report on the biological diversity of the cryptofauna associated with dead coral fragments of Montastraea annularis (Ellis and Solander, 1786), comparing these between coral reefs from continental and oceanic regions. Dead fragments were taken from coral colonies at two depths at each locality, and the associated fauna were extracted and identified to taxonomic group. Polychaetes were separated by family, and by species for the most common family (Eunicidae) identified. The cryptofauna from both regions were mainly composed of polychaetes, sipunculids, and crustaceans. Polychaetes were the most abundant at the continental sites and sipunculids at the oceanic sites. A significantly higher diversity and density of cryptofauna were found at the continental region. Likewise, at the level of polychaete family, results also showed a clear spatial pattern: higher abundance and diversity at continental reefs. In total, 26 families of polychaetes were distinguished: 14 were common to both regions, three were exclusive to the oceanic reefs, and nine were exclusive to the continental regions. Eunicidae was the family with the highest percentage of individuals at both regions. Other important families were Sabellidae, Syllidae, and Nereididae. From the 17 eunicid species reported, eight belonged to the oceanic region, with Lysidice ninetta Audouin and Milne-Edwards, 1833 the most abundant, and 11 to the continental region, with Eunice cariboea Grube, 1856, Marphysa longula Ehlers, 1887, Marphysa cf longula, and L. ninetta as dominants. Significantly higher densities in continental reefs relative to oceanic reefs regardless of the level of taxonomic resolution may reflect reduced coral density or higher substrata availability at continental reefs.

Harpacticoid copepod colonization of coral fragments in a tropical reef lagoon (Zanzibar, Tanzania)

Colonization experiments were conducted in a tropical lagoon (Zanzibar Island, off the coast of Tanzania) to investigate the temporal dynamics and mode of colonization of the harpacticoid copepods community on dead coral fragments. There was fast colonization of the coral fragments attaining a substantial diversity after only two days. The ability to colonize dead coral fragments is thought to be related to the morphology and life style of different harpacticoid species. Phytal taxa (e.g. Tisbidae) were fast colonizers, reaching high abundances during the initial colonization phase. Sediment-associated and eurytopic taxa (e.g. Ameiridae, Miraciidae and Ectinosomatidae) showed lower colonization rates and became the dominant group during the later colonization phase. Most species are able to colonize the coral fragments through the water column. However, colonization along the substrate surface is also considered to be an important colonization mode, especially for sediment-associated taxa, which showed lower colonization rates when migration through the sediment was hindered.

Cold-water coral habitats in the Penmarc'h and Guilvinec Canyons (Bay of Biscay): Deep-water versus shallow-water settings

In 1948, Le Danois reported for the first time the occurrence of living cold-water coral reefs, the so-called “massifs coralliens”, along the European Atlantic continental margin. In 2008, a cruise with R/V Belgica was set out to re-investigate these cold-water corals in the Penmarc'h and Guilvinec Canyons along the Gascogne margin of the Bay of Biscay. During this cruise, an area of 560km2 was studied using multibeam swath bathymetry, CTD casts, ROV observations and USBL-guided boxcoring.Based on the multibeam data and the ROV video imagery, two different cold-water coral reef settings were distinguished. In water depths ranging from 260 to 350m, mini mounds up to 5m high, covered by dead cold-water coral rubble, were observed. In between these mounds, soft sediment with a patchy distribution of gravel was recognised. The second setting (350–950m) features hard substrates with cracks, spurs, cliffs and overhangs. In water depths of 700 to 950m, both living and dead cold-water corals occur. Occasionally, they form dense coral patches with a diameter of about 10–60m, characterised by mostly stacked dead coral rubble and a few living specimens. U/Th datings indicate a shift in cold-water coral growth after the Late Glacial Maximum (about 11.5ka BP) from shallow to deep-water settings.The living cold-water corals from the deeper area occur in a water density (sigma–theta) of 27.35–27.55kgm−3, suggested to be a prerequisite for the growth and distribution of cold-water coral reefs along the northern Atlantic margin. In contrast, the dead cold-water coral fragments in the shallow area occur in a density range of 27.15–27.20kgm−3 which is slightly outside the density range where living cold-water corals normally occur. The presented data suggest that this prerequisite is also valid for coral growth in the deeper canyons (>350m) in the Bay of Biscay.

Discovery of Novocriniidae (Copepoda, Harpacticoida) from cold-water corals in the Porcupine Seabight (NE Atlantic), with description of a new species of Atergopedia

The female of Atergopedia longicaudata sp. n. is described from dead cold-water coral fragments collected from the Porcupine Seabight (NE Atlantic). The new species is the fourth representative of the family Novocriniidae (Copepoda, Harpacticoida); it can be distinguished from its congeners by the elongate caudal rami and the ancestral armature on enp-3 of P1. Rediscovery of Atergopedia vetusta Martínez Arbizu & Moura, 1998, originally described from the Arctic Barents Sea, results in corrections to the species description. Archaeotisbe confluenta Kornev & Chertoprud, 2008 is transferred to the genus Atergopedia Martínez Arbizu & Moura, 1998, and Archaeotisbe Kornev & Chertoprud, 2008 is newly treated as a junior synonym of Atergopedia. Diagnoses (as ground patterns) for the two novocriniid genera ( Atergopedia and Novocrinia Huys & Iliffe, 1998) are provided, and autapomorphies are indicated.

Walking with worms: coral‐associated epifaunal nematodes

AbstractAims To study the community structure and habitat preferences of the Epsilonematidae and Draconematidae in coral degradation zones. To assess the contribution of different localities and microhabitats to meiobenthic diversity in such ecosystems. To discuss dispersive capacities and the occurrence of cryptic species in meiobenthic organisms.Location Porcupine Seabight (north‐east Atlantic Ocean; continental slope) and a transect along the Kenyan coast (Indian Ocean; shallow lagoon).Methods In the north‐east Atlantic, dead coral fragments, sponge skeletons and sediment were collected with a boxcorer. Along the Kenyan coast, dead coral fragments and coral gravel were collected during snorkelling and skin diving. Only nematodes belonging to the families Epsilonematidae and Draconematidae were considered. Community structure was analysed using multivariate techniques. Biodiversity was represented via rarefaction curves. Additive partitioning of species diversity was conducted. Turnover between microhabitats within locations and between locations within microhabitats were compared in a ternary plot.Results Twelve epsilonematid and five draconematid species were found in the Porcupine Seabight. In Kenya, 39 epsilonematid and 20 draconematid species were distinguished. Three species were found at both sampling locations. A table with the known distribution of all currently described species encountered in our study area is provided. At both sampling locations, the communities on coral fragments were significantly different from those in the other microhabitats, and were most diverse. In Kenya, species richness was mainly determined by local diversity and by turnover between localities. The contribution of β‐diversity decreased when abundance data were analysed. Turnover between microhabitats and between coral samples from different localities was higher than turnover between locations for gravel samples.Main conclusions Coral fragments were recognized as favourable substrata for typically epifaunal nematodes. Species‐specific habitat preferences were explained by finely tuned morphological adaptations. Our results suggest that cosmopolitan species could well be cryptic species, and this explanation for the existence of morphologically identical nematodes in geographically distant areas is weighed up against other plausible explanations. Coral degradation zones are an important source for new species of Epsilonematidae and Draconematidae. The addition of sampling locations contributed to the total number of species, although the added species were generally rare.

Dynamics and patterns of algal colonization on mechanically damaged and dead colonies of the coral Porites lutea

Abstract We studied (1) the dynamics of colonization by epilithic algae on mechanically damaged colonies of the coral Porites lutea, (2) the dynamics of algal colonization on dead coral fragments (coral pebbles), (3) and regeneration rates of the damaged corals under a broad range of natural light conditions on the fringing reef of Sesoko Island (Okinawa, Japan). After 1 month (of the experiment), 26 algal species occupied damaged coral areas with a projected areal cover of 1–7%. Colonizers were mainly diatoms, Cyanobacteria, filamentous green, brown and red algae. During this period, the algal settlers were not an impediment to coral polyp recovery. The recovery rate of damaged coral tissue was highest after the first month, amounting to approximately 0.15 mm day-1 under bright light (70–90% of incident surface photosynthetically active radiation, PAR0), 0.14 mm day-1 under moderate light (20–30% PAR0) and 0.07 mm day-1 under low light (2–5% PAR0). After 3 months, 58 algal species had settled onto lesions and 43 species onto coral pebbles. Projected areal cover of the algae was 30–90%. After the second month of the experiment, the recovery rates of corals declined sharply to 0.02–0.04 mm day-1. Under high and moderate light intensities, the measured parameters were similar (with the exception of the number of algal settlers). Under low light, the number, the density of algal settlers and the regeneration rate of polyps on damaged corals were significantly reduced. The algal turf community was formed under light intensities from 20% to 90% PAR0, but was not formed under low light.

Community structure and microhabitat preferences of harpacticoid copepods in a tropical reef lagoon (Zanzibar Island, Tanzania)

Three microhabitat types (dead coral fragments, coral gravel and coral sand) were distinguished and sampled at two locations (Matemwe and Makunduchi) in a tropical lagoon (Zanzibar Island, Tanzania), and the community structure, habitat preferences and biodiversity of the associated harpacticoid copepod fauna was investigated. The harpacticoid fauna is affected by sediment granulometry and by the structural differences between coral and both gravel and sediment. The coral fragments contained a specific assemblage composed of typical ‘phytal’ taxa(Tisbe,ParadactylopodiaandDactylopusia)along with other eurytopic and sediment-dwelling forms (Ameira,EctinosomaandAmphiascus), which may be attracted by the sediment retained between the coral branches. The assemblages of coral gravel and upper sediment layer did not differ significantly from each other and had mostly the same dominant genera. The sediment from Matemwe was dominated by the interstitial Paramesochridae and the sediment from Makunduchi by Tetragonicipitidae. The coral fragments from Makunduchi sustained a more diverse assemblage than gravel and the different sediment layers. It was assumed that coral form and complexity, with implications for habitable space, nutritional resources and level of predation, are important in structuring diversity of the associated assemblage.

A new species of Halophytophilus Brian, 1919 (Copepoda: Harpacticoida: Ectinosomatidae) from cold-water corals in the Porcupine Seabight (NE Atlantic)

The first deep-sea representative of Halophytophilus Brian, 1919 is described from samples of dead cold-water coral fragments, glass sponge skeletons and underlying sediment collected from the Porcupine Seabight (NE Atlantic). Halophytophilus lopheliae sp. nov. can be distinguished from its congeners by the dimensions of the P1 endopod and the position of the inner seta on its proximal segment. Moreover, we present the first description of a male in this genus. The occurrence of Halophytophilus and three other ectinosomatid genera with prehensile first legs is remarkable in the deep sea and an indication that the hard substrates of the coral degradation zone may provide an exceptional habitat. A key to the five species of Halophytophilus is included.

Seasonal changes of benthic and epiphytic dinoflagellates in the Veracruz reef zone, Gulf of Mexico

Benthic/epiphytic dinoflagellates were monitored every 2 wk from May to December 2005 in the Veracruz reef zone, Gulf of Mexico. This assemblage was characterized by low species diversity (at least 17 species from 11 genera) and high abundance: Amphidinium cf. carterae (41 172 cells g -1 substrate wet weight), Prorocentrum lima (29 756 cells g -1 ), Coolia monotis (2724 cells g -1 ), Ostreopsis heptagona (1202 cells g -1 ); P. lima was the dominant species. Clear sea- sonal population dynamics occurred, with the highest abundance in May-June, and the dynamics differed at 2 neighbouring sampling sites. In August to December dinoflagellate abundance de- creased considerably. Most of the epiphytic dinoflagellates did not show any significant preference for a macrophyte substrate (23 macroalgal and 2 seagrass species) or for any species or major algal group, although the seagrass Thalassia testudinum appeared to be the most abundant and perma- nent host species. The highest abundance of P. lima occurred on the chlorophyte Ulva fasciata (30 879 cells g -1 ) and T. testudinum (31 467). Dinoflagellates were usually scarce on dead coral (Acro- pora sp. and Millepora alcicornis) fragments (0 to 5039 cells g -1 ) and surface bottom sediments (2 to 84), and were slightly more abundant on living Diploria strigosa (329 to 1830) and more numerous in a fringing reef zone compared to a reef lagoon near an offshore island. Dinoflagellate abundance was not correlated with any measured physical or chemical parameter (temperature, salinity, pH, dis- solved oxygen, nitrates, nitrites, ammonium, phosphates, precipitation or wind speed and direction). There is a high potential for outbreaks of ciguatera in the studied area.

Microhabitat type determines the composition of nematode communities associated with sediment-clogged cold-water coral framework in the Porcupine Seabight (NE Atlantic)

The nematofauna associated with a cold-water coral degradation zone in the Porcupine Seabight (NE Atlantic) was investigated. This is the first comprehensive study of nematodes associated with cold-water corals. This research mainly aimed to investigate the influence of microhabitat type on nematode community structure. Three distinct microhabitats for nematodes were distinguished: dead coral fragments, glass sponge skeletons and the underlying sediment. The nematode assemblages associated with these three microhabitats were significantly different from each other. Coral and sponge substrata lie relatively unprotected on the seafloor and are consequently more subjected to strong currents than the underlying sediment. As a result, both large biogenic substrata were characterized by higher abundances of taxa that are less vulnerable and more adapted to physical disturbance, whereas the underlying sediment yielded more slender, sediment-dwelling taxa. Typically epifaunal taxa, such as Epsilonematidae and Draconematidae, were especially abundant on dead coral fragments, where they are thought to feed on the microbial biofilm which covers the coral surface. Several epifaunal genera showed significant preferences for this microhabitat, and Epsilonema (Epsilonematidae) was dominant here. Sponge skeletons are thought to act as efficient sediment traps, resulting in a lower abundance of epifaunal taxa compared to coral fragments. The underlying sediment was dominated by taxa typical for slope sediments. The considerable degree of overlap between the communities of each microhabitat is attributed to sediment infill between the coral branches and sponge spicules. It is assumed that the nematofauna associated with large biogenic substrata is composed of a typical sediment-dwelling background community, supplemented with taxa adapted to an epifaunal life strategy. The extent to which these taxa contribute to the community depends on the type of the substratum. Selective deposit feeders were dominant on sponge skeletons and in the underlying sediment, whereas coral fragments were dominated by epistratum feeders. The presence of a microbial biofilm on the coral fragments is proposed as an explanation for the significant preference of epistratum feeders for this microhabitat. Densities in the underlying sediment were low in comparison with other studies, but biodiversity was higher here than on the coral and sponge fragments, a difference which is attributed to lower disturbance. Nevertheless, the large biogenic substrata provide a microhabitat for rare, epifaunal taxa, and fragments of both substrata within the sediment increase habitat complexity and hence biodiversity.