Massive Colonies Research Articles

Recovery of the algae and macroinvertebrate benthic community after Didymosphenia geminata mass growths in Spanish rivers

This study aims to assess the ecological profile of the invasive alga Didymosphenia geminata in NW Spain, analysing the biotic and abiotic factors related to the presence of massive colonies and their effect on river benthos. Physical and chemical parameters were measured in three infested rivers during 2009 and 2010, and biological samples of benthic community were taken according to standard protocols. Collected data was compared with that of control stations located in the same rivers but presenting no evident infestations. The autoecology shown by D. geminata in this study supports former observations reporting the expansion of its ecological niche, with current velocity and nutrients concentrations the environmental variables that best explain the establishment and development of mats in the studied rivers. Regarding its impact, it was observed that the mass growths of this diatom produced a dramatic change in the composition of the algae and macroinvertebrate benthic community which persisted after their disappearance. These results led to the development of a geostatistical predictive model to identify potential risk of dispersion of this diatom in Spanish rivers. The expected distribution of this algae according to this model agreed in general with the actual observed infestations, thus validating it as a tool to prevent and manage future infestations.

Adaptive Radiation in Socially Advanced Stem-Group Ants from the Cretaceous

Across terrestrial ecosystems, modern ants are ubiquitous. As many as 94 out of every 100 individual arthropods in rainforests are ants, and they constitute up to 15% of animal biomass in the Amazon. Moreover, ants are pervasive agents of natural selection as over 10,000 arthropod species are specialized inquilines or myrmecomorphs living among ants or defending themselves through mimicry. Such impact is traditionally explained by sociality: ants are the first major group of ground-dwelling predatory insects to become eusocial, increasing efficiency of tasks and establishing competitive superiority over solitary species. A wealth of specimens from rich deposits of 99 million-year-old Burmese amber resolves ambiguity regarding sociality and diversity in the earliest ants. The stem-group genus Gerontoformica maintained distinct reproductive castes including morphotypes unknown in solitary aculeate (stinging) wasps, providing insight into early behavior. We present rare aggregations of workers, indicating group recruitment as well as an instance of interspecific combat; such aggression is a social feature of modern ants. Two species and an unusual new genus are described, further expanding the remarkable diversity of early ants. Stem-group ants are recovered as a paraphyletic assemblage at the base of modern lineages varying greatly in size, form, and mouthpart structure, interpreted here as an adaptive radiation. Though Cretaceous stem-group ants were eusocial and adaptively diverse, we hypothesize that their extinction resulted from the rise of competitively superior crown-group taxa that today form massive colonies, consistent with Wilson and Hölldobler's concept of "dynastic succession."

CORAL REEFS OF GORGONA ISLAND, COLOMBIA, WITH SPECIAL REFERENCE TO CORALLIVORES AND THEIR INFLUENCE ON COMMUNITY STRUCTURE AND REEF DEVELOPMENT

This study offers an overview of the distribution and structure of coral reefs and coral communities at Gorgona Island, off the Pacific coast of Colombia. Biotic interactions, mainly the effects of corallivores, are examined and compared with coral communities elsewhere in the eastern Pacific in order to provide a basis for understanding regional differences in community structure. Located at the south end of the Panamá Bight and ca. 30 km offshore, Gorgona is largely removed from the influence of upwelling and freshwater dilution. The key corallivore Acanthaster, which is widely distributed in the tropical eastern Pacific, is absent from Gorgona, probably a result of unfavorable physical conditions (low temperatures and low salinites) for larval development in the Panamá Bight area. True fringing coral reefs are present at Gorgona and are best developed on the eastern or leeward side, but they also occur in one area on the western and exposed side of the island. The La Azufrada reef, the largest of the fringing reefs, was about 1 km long and 150 m wide, had a minimum thickness of 8 m and supported live corals to a depth of 15 m. Pocilloporid corals predominated on the reef crest and upper to mid forereef slope, and massive and small species increased in relative abundance in the deep forereef and sand plain zones. A corallivorous pufferfish and ovulid gastropod were abundant, but other known corallivores (e. g., Acanthaster, hermit crabs and Eucidaris) were either absent, uncommon or not feeding on live coral. Damage inflicted on live massive colonies by a damselfish, in order to "farm" algae, could play an important role in altering the relative abundances of corals in shallow reef zones. A comparison of coral reefs at Gorgona and Panamá, in areas with and without Acanthaster, show that nonpocilloporid corals, which are preferred prey items, have a higher relative abundance on reefs where the predatory sea star is absent.

Contrasting Lesion Dynamics of White Syndrome among the scleractinian corals Porites spp.

White syndrome (WS) is currently the most prevalent disease of scleractinian corals in the Indo-Pacific region, with an ability to exist in both epizootic and enzootic states. Here, we present results of an examination of WS lesion dynamics and show that potentially associated traits of host morphology (i.e., branching vs. massive), lesion size, and tissue deposition rate influence disease severity and recovery. Lesion healing rate was positively correlated with initial lesion size in both morphologies, but the rate at which lesions healed differed between morphologies. New lesions in branching Porites cylindrica appeared less frequently, were smaller and healed more quickly, but were more abundant than in closely-related massive Porites sp(p). The positive association between lesion size and healing rate was partly explained by geometry; branching limited lesion maximum size, and larger lesion margins contained more polyps producing new tissue, resulting in faster healing. However, massive colonies deposited tissue more slowly than branching colonies, resulting in slower recovery and more persistent lesions. Corallite size and density did not differ between species and did not, therefore, influence healing rate. We demonstrated multiple modes of pathogen transmission, which may be influenced by the greater potential for pathogen entrainment in branching vs. massive morphologies. We suggest that attributes such as colony morphology and species-specific growth rates require consideration as we expand our understanding of disease dynamics in colonial organisms such as coral.

Low calcification rates and calcium carbonate production in Porites panamensis at its northernmost geographic distribution

AbstractPorites panamensis is a hermatypic coral present in the eastern Pacific Ocean. Skeletal growth parameters have been reported, but studies of the relationship between annual calcification rates and environmental controls are scarce. In this study, we investigated three aspects of the annual calcification rates of P. panamensis: growth parameters among three P. panamensis populations; the sea surface temperature as a calcification rate control spanning a latitudinal gradient; and calcium carbonate production among three sites. Growth parameters varied among the sites due to the colony growth form. Massive colonies in the north showed a higher calcification rate than encrusting colonies in the south (mean: 1.22–0.49 g CaCO3 · cm−2 · yr−1), where variations in calcification rates were related to growth rate (0.91–0.38 cm · yr−1) rather than to skeletal density differences (overall mean ± SD, 1.31 ± 0.04 g CaCO3 · cm−3). Our results showed a positive linear relationship between annual calcification rates and sea surface temperatures within these P. panamensis populations. Differences were related to distinct oceanographic environments (within and at the entrance of the Gulf of California) with different sea surface temperature regimes and other chemical properties. Different populations calcified under different environmental conditions. Calcium carbonate production was dependent upon the calcification rate and coral cover and so carbonate production was higher in the north (coral cover 12%) than in the south (coral cover 3.5). Thus, the studied sites showed low calcium carbonate production (0.25–0.43 kg CaCO3 · m−2 · yr−1). Our results showed reduced calcification rates, regional temperature regime control over calcification rates, different growth forms, low coral cover and low calcium carbonate production rates in P. panamensis.

Clustered parrotfish feeding scars trigger partial coral mortality of massive Porites colonies on the inshore Great Barrier Reef

Coral predation by parrotfishes can cause damage to coral colonies, but research into the dynamics of their feeding scars on Indo-Pacific corals is limited. We monitored feeding scars of the parrotfish Chlorurus microrhinos on massive Porites colonies at Orpheus Island (inshore Great Barrier Reef) over 4 months. Of the 30 marks monitored, 11 were single feeding scars, which all healed completely. The remaining 19 feeding marks consisted of clusters of scars. Eight began to recover, while 11 increased in size by 1,576 ± 252 % (mean ± SE). A logistic regression predicted that a single feeding scar on a Porites colony had a 97 % probability of healing; however, where more than three feeding scars were present, this dropped below 50 %. As excavating parrotfishes in the Indo-Pacific often take multiple focused bites, they may have a significant impact on the growth and mortality of massive Porites colonies at Orpheus Island.

Paleobathymetry and paleoecology of colonial corals from the Oligocene–early Miocene (?) Qom Formation (Dizlu area, central Iran)

The scleractinian corals from the carbonate facies of the Oligocene–early Miocene (?) Qom Formation in Dizlu area (northern Isfahan), central Iran were described in three separate coral intervals. From the base to the top of the study carbonate sequence, the coral assemblages of the intervals include 1—Madracis, 2—Leptoseris–Stylophora and 3—Poritidae–Faviidae–Siderastreidae. The species identified within the carbonates are dominated by: Goniopora sp., Pachyseris sp., Madracis cf. ornate, Madracis sp., Montastraea parva, Solenastrea cf. desmoulinsi, Tarbellastraea reussiana, Stylophora sp., Siderastrea crenulata and Leptoseris sp. The identified colonial coral species were not colonizing through a strong carbonate reefal structure. Instead, they were distributed as sparse patches or building coral biostromal frameworks. The thin branching colonies of Madracis species and the second coral assemblage (Leptoseris–Stylophora) that is dominated by thin branching and thin platy colonial growth forms reflect deeper depths of a carbonate ramp with low light intensity within the lower photic zone in a depth range of 19–35 m and a maximum flooding surface. The coral associations of the Poritidae–Faviidae–Siderastreidae assemblage are mainly composed of massive colonies indicating the upper photic zone with depth of less than 20 m and a higher energy water regime. The three coral assemblages reflect marine paleotemperature of 19–20° C, respectively.

Molecular genetic and chemotaxonomic characterization of the terrestrial cyanobacterium Nostoc commune and its neighboring species

The phylogeny of the terrestrial cyanobacterium Nostoc commune and its neighboring Nostoc species was studied using molecular genetic and chemotaxonomic approaches. At least eight genotypes of N. commune were characterized by the differences among 16S rRNA gene sequences and the petH gene encoding ferredoxin-NADP⁺ oxidoreductase and by random amplified polymorphic DNA analysis. The genotypes of N. commune were distributed in Japan without regional specificity. The nrtP gene encoding NrtP-type nitrate/nitrite permease was widely distributed in the genus Nostoc, suggesting that the occurrence of the nrtP gene can be one of the characteristic features that separate cyanobacteria into two groups. The wspA gene encoding a 36-kDa water stress protein was only found in N. commune and Nostoc verrucosum, suggesting that these Nostoc species that form massive colonies with extracellular polysaccharides can be exclusively characterized by the occurrence of the wspA gene. Fifteen species of Nostoc and Anabaena were investigated by comparing their carotenoid composition. Three groups with distinct patterns of carotenoids were related to the phylogenic tree constructed on the basis of 16S rRNA sequences. Nostoc commune and Nostoc punctiforme were clustered in one monophyletic group and characterized by the occurrence of nostoxanthin, canthaxanthin, and myxol glycosides.

Patterns of distribution of calcite crystals in soft corals sclerites

The gross morphology of soft coral surface sclerites has been studied for taxonomic purposes for over a century. In contrast, sclerites located deep in the core of colonies have not received attention. Some soft coral groups develop massive colonies, in these organisms tissue depth can limit light penetration and circulation of internal fluids affecting the physiology of coral tissues and their symbiotic algae; such conditions have the potential to create contrasting calcifying conditions. To test this idea, we analyzed the crystal structure of sclerites extracted from different colony regions in selected specimens of zooxanthellate and azooxanthellate soft corals with different colony morphologies, these were: Sarcophyton mililatensis, Sinularia capillosa, Sinularia flexibilis, Dendronephthya sp. and Ceeceenus levis. We found that the crystals that constitute polyp sclerites differ from those forming stalk sclerites. We also observed different crystals in sclerites located at various depths in the stalk including signs of sclerite breakdown in the stalk core region. These results indicate different modes of calcification within each colonial organism analyzed and illustrate the complexity of organisms usually regarded as repetitive morphological and functional units. Our study indicates that soft corals are ideal material to study natural gradients of calcification conditions.

The genome sequence of the leaf-cutter ant Atta cephalotes reveals insights into its obligate symbiotic lifestyle.

Leaf-cutter ants are one of the most important herbivorous insects in the Neotropics, harvesting vast quantities of fresh leaf material. The ants use leaves to cultivate a fungus that serves as the colony's primary food source. This obligate ant-fungus mutualism is one of the few occurrences of farming by non-humans and likely facilitated the formation of their massive colonies. Mature leaf-cutter ant colonies contain millions of workers ranging in size from small garden tenders to large soldiers, resulting in one of the most complex polymorphic caste systems within ants. To begin uncovering the genomic underpinnings of this system, we sequenced the genome of Atta cephalotes using 454 pyrosequencing. One prediction from this ant's lifestyle is that it has undergone genetic modifications that reflect its obligate dependence on the fungus for nutrients. Analysis of this genome sequence is consistent with this hypothesis, as we find evidence for reductions in genes related to nutrient acquisition. These include extensive reductions in serine proteases (which are likely unnecessary because proteolysis is not a primary mechanism used to process nutrients obtained from the fungus), a loss of genes involved in arginine biosynthesis (suggesting that this amino acid is obtained from the fungus), and the absence of a hexamerin (which sequesters amino acids during larval development in other insects). Following recent reports of genome sequences from other insects that engage in symbioses with beneficial microbes, the A. cephalotes genome provides new insights into the symbiotic lifestyle of this ant and advances our understanding of host–microbe symbioses.

Distribution pattern, reproductive traits, and molecular analysis of two coexisting vermetid gastropods of the genus Petaloconchus: a Caribbean endemic and a potential invasive species

Vermetid gastropods are characterized by complex taxonomy and unusual ecology. A survey of the fouling community in the intake channel at the Planta Centro Power Plan in Puerto Cabello, Venezuela, found massive colonies of vermetid gastropods of the genus Petaloconchus. We arbitrarily named two prevalent varieties as black and brown-orange morphs, distinguishing based on the color of their soft bodies. Spatial distribution was different for the morphs. The black morph was present along the jetty, with higher average densities in the shallower intertidal area (410 vs. 143 ind m−2), while the brown-orange morph was only present at the initial part of the channel (μ = 83 ind m−2). Both produced small eggs (142 vs. 180 μm diameter on average), with the orange-brown eggs being slightly larger, but the morphs differed in other reproductive aspects. The brown-orange morph produced significantly fewer capsules (up to nine simultaneously per female) with fewer embryos (average of 27 viable embryos/capsule) that hatched at a larger size (577 μm on average), allocating about 17.64% of the initial egg production to nurse eggs. In contrast, the black morph produced up to 14 capsules simultaneously, hatched an average of 178 veligers of 212 μm, and produced no nurse eggs. The intra-capsular development reached a more advanced stage in the brown-orange morph than in the black one. Several cytochrome subunit I (COI) and 16S rRNA (16S) haplotypes were found for the black morph, when compared to only one haplotype for both genes present for the brown-orange morph. Preliminary phylogenetic analyses separated the morphs into different clades, supported by robust bootstrap values and posterior probabilities (>98). Our results indicate that the morphs are two different species: the black morph was identified as Petaloconchus cf. varians and the brown-orange morph as a non-described species, Petaloconchus sp. (orange). The first is endemic to the Caribbean, while the second is potentially an introduced species.

Evolution of the colonial growth habit in the ordovician bryozoans of the class stenolaemata: Feeding adaptations (Leningrad Region, Russia)

Based on the study of the growth habits and the relief of the colony surface in bryozoans of the class Stenolaemata from the Lower (Latorp horizon) and Middle (Volchov and Kunda horizons) Ordovician of the Leningrad Region, these bryozoans are shown to develop from the simple, unilaminate colonies (BIβ) to the massive colonies with a nodular surface and smooth columnar colonies (BIIα), which subsequently evolved into the columnar-spiral (BIIβ) and more complex erect branching and fenestrate constructions (BIIγ), and subsequently into the branching, articulate colonies (BIIIα). The apertures of autozooecia and the character of their arrangement on the colony surface changed correlatively from the circular (BIβ) to polygonal and roundedpolygonal, randomly arranged apertures, and subsequently to the oval apertures (BIIIα) arranged in strictly regular longitudinal or longitudinal-diagonal rows or in a quincuncial pattern. Thus, the development of growth habits in the bryozoans under consideration has a progressive character. It is expressed in the progressive increase in the complexity of growth habits of colonies and in the more regular arrangement of apertures and other structures on the colony surface. The directionality of morphological changes in the growth habits of colonies of Ordovician bryozoans was apparently closely associated with the development of more complex environmental interactions of these bryozoans, especially with water currents supplying food particles. It is suggested that the high competitive ability of bryozoans of the class Stenolaemata at early stages of its development in the basin of Baltoscandia was apparently due to the better use of food resources.

Mediterranean climate variability documented in oxygen isotope records from northern Red Sea corals—A review

Annually banded reef corals from the northern Red Sea provide a high-resolution archive of past climate variations at the southeastern rim of the Mediterranean basin. Subseasonally resolved oxygen isotope records derived from the carbonate skeletons of these massive colonies robustly document seasonality and interannual to decadal climate variability. These proxy records of climate, supported by analyses of instrumental data and model simulations, reveal the prominent role of the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) in controlling eastern Mediterranean/Middle East climate on seasonal, interannual to decadal and orbital timescales, most pronounced during winter. Variability at interannual periods of 5–6 yr evident in the coral records is indicative of AO/NAO-like atmospheric variability over the Northern Hemisphere and its influence on eastern Mediterranean/Middle East climate during the last centuries, the late Holocene and the last interglacial period. The coral oxygen isotope records, which are recording temperature and surface evaporation in the northern Red Sea, are linked via AO/NAO-controlled atmospheric circulation changes to variations in temperature and precipitation throughout the Mediterranean and Middle East region. Whereas the entire eastern Mediterranean/Middle East region experiences colder winters during the high-index state of the AO/NAO, the resulting changes in hydrologic balance have a more complex spatial pattern. More arid conditions in the northern Red Sea are accompanied by drier winters in the northeastern Mediterranean but by wetter winters along the southeastern rim of the Mediterranean Sea. This observation may raise difficulties for proxy-based reconstructions of eastern Mediterranean precipitation from the Levant, which is located in the transition zone between positive and negative precipitation anomalies. Compared to the AO/NAO, the atmospheric teleconnections of the El Niño-Southern Oscillation (ENSO) on eastern Mediterranean/Middle East climate, which are modulated by higher-latitude atmospheric circulation over the North Pacific-North Atlantic region, are weaker and non-stationary.

Modern microbialites and their environmental significance, Meiji reef atoll, Nansha (Spratly) Islands, South China Sea

Meiji (Mischief) coral atoll, in Nansha (Spratly) Islands, South China Sea, consists of an annular reef rim surrounding a central lagoon. On the atoll rim there are either protuberant ‘motu’ (small coral patch reefs on the rim of atoll) islets or lower sandy cays that contain modern microbialite deposits on the corals in pinnacles and surrounding bottoms of the atoll. Microbialites, including villiform, hairy, and thin spine growth forms, as well as gelatinous masses, mats and encrustation, developed on coral colonies and atoll rim sediments between 0 and 15 m deep-water settings. The microbialites were produced by natural populations of filamentous cyanobacteria and grew on (1) bulbous corals together with Acropora sp., (2) on massive colonies of Galaxea fascicularis, (3) on dead Montipora digitata, and (4) on dead Acropora teres, some hairy microbialite growing around broken coral branches. This study demonstrates that microbial carbonates are developed in coral reefs of South China Sea and indicates that microbial processes may be important in the construction of modern reef systems. The results have significance in the determination of nature and composition in microorganisms implied in the formation ancient microbialites, and permit evaluation of the importance of microbial deposits in modern coral reefs and of ‘microbialites’ in biogeochemical cycles of modern coral reef systems. The results also provide evidence of modern analogues for ancient microbialites in shallow-water settings, and combine with sedimentological studies of ancient microbialites to understand their controls.

High resolution stable isotope records of sclreractinian corals near Ishigaki Island: Their implication as a potential paleoclimatic recorder in middle latitude regions

We propose skeletal δ18O of Platygyra, a hermatypic reef building massive coral, as a potential paleo-SST proxy in midlatitude regions, where the commonly used massive Porites corals are rare. Skeletal δ18O ratio (δ18Oc) of a Platygyra and Porites corals collected from Ishigaki Island, Japan, shows a clear seasonality corresponding to SST variation. The temperature dependence of the Platygyra coral was estimated, for the first time with appropriate sampling resolution, at −0.219‰/°C (T = −4.57δ18Oc + 2.65, r2=0.96). Massive Platygyra colonies show a wide distribution from the tropics to mid-latitudes further northwards than Porites. Platygyra’s adaptation to colder water temperatures and strong temperature dependence of δ18Oc suggest its application as a potential paleo-SST proxy for mid-latitude regions, where high resolution SST proxies are not available, as well as in tropical to subtropical regions.

Benthic community associated with coral reefs in the coastal area of Gulf of Aqaba, Red Scs, Egypt

Benthic community associated with coral reefs was investigated at four sites along the coastline of Gulf of Aqaba, Red Sea Egypt. The four sites (Taba, Nuweiba, Dahab and Shann El-Sheikh) are important popular spots for recreational activities and the reefs of these sites are of fringing type. Drupella cornus and Trochus maculatus were the most important gastropods associated with coral reefs. Taba and Sharm El-Sheikh showed high occurrence of worm shells (Gastropoda) Dendropdma maximum (up to 30 individuals / colony). Concerning the abundance of bivalves (Mollusca), Taba showed greater abundance of Spondylus varium and Pteria penguin ^ whereas Sharm El-Sheikh had the greatest abundance of Tridacna maxima (up to 40 individuals/lOm). The studied sites exhibited high density of Echinoderms, particularly the sea urchins Diadema setosvm, Tripneitstes gratilla and Heterocentrotus mammillatus. The study revealed selective associations between mollusc species and coral growth forms. The bivalve Pteriapenguin was found to be attached with plate-like coral Mellipora platyphylla and the branching coral Millepora dichotoma. The vennetid gastropod Dendropoma maximum was also found to be inserted into the Melliporid coral colonies. Aggregates of Drupella cornus were observed attached with branching corals, especially Acropora spp. and Stylophora spp. In contrast to the Drupella cornus, the corallivore gastropod CoralUphila neritoidea and the bivalve Tridacna maxima were predominantly preying on the massive corals of Poriies spp. The distribution of coral growth forms was compared. In general, massive, branched and plate-like colonies were the dominant growth forms of corals in the area of study. Massive colonies were dominant in the reef flat area, reef margin and the deep parts of the outer reef slope. Branching coral colonies were flourishing on the fringing reef flat, the barrier reef flat and the outer reef slope until 10m depth (upper layers of outer reef slope), their importance declined with depth. All plate-like coral colonies in the area of study belong to Hydrocorals (Milleporidae); Millepora platyphyla. They are abundant in the reef edge and upper zone of outer reef slope (the reef zone exposed to high wave action). The considerable abundance of macroalgae in the coral communities of the sampling sites were probably resulting from increased levels of nutrients caused by enhanced terrestrial runoff of sewage and sediments concomitant with increased human pressure in the area and coastal

Three stages of injuries regeneration on scleractinian corals

Regeneration of artificial injuries on scleractinian corals of massive colonies Porites lutea and branching Porites cylindrica and algal/coral competition on newly formed substrate are the subject of investigation. It was shown that the injured coral areas recovered at three stages (1) coral tissue recovery with the formation of a border between the regenerating live tissue and dead area, (2) growth and expansion of the live tissue on the substrate, and (3) new polyps development on the healed area. At the first stage of the regeneration, the rate of lesion healing was highest; it varied in respect to injury type and averaged 0.2-0.05 and 0.1-0.02mm day-1 for P. lutea and P. cylindrica, respectively. The regeneration rate mostly depended on morphology of corals and injury type. Coral entombed spores and thalli fragments of algae settled onto partially damaged live tissue and skeleton. At the second stage, the rate of lesion healing sharply decreased and varied from 0.1 to 0.03mm day-1 for P. lutea and from 0.05 to 0.02mm day-1 for P. cylindrica. Position of the injuries within the colony, light intensity, as well as the composition and abundance of algae and animals settled onto the damaged areas had a significant effect on the rate and duration of the recovery process. The algae growing on dead areas of the injuries acted as a physical and in rare cases as a chemical impediment for expansion of live tissue on the available substrate. At the second stage of healing, the live tissue overgrew twenty two algal species settled onto the lesions at winter and spring seasons. At the third stage of the regeneration, the recovery depended on external and internal conditions promoting the growth of coral polyps.

Las enfermedades en corales escleractinidos: ¿un nuevo problema en el arrecife de Cayo Sombrero, Parque Nacional Morrocoy, Venezuela?

At the beginning of 1996 coral reefs in Morrocoy National Park, Venezuela, suffered an unprecedented mass mortality event. As a consequence, live coral cover dropped to 2-10%. One of the few reefs that kept live coral cover over 35% was Cayo Sombrero; nonetheless, the presence of some coral diseases has been detected within the past 2 years, representing a new source of coral mortality. Due to this situation, this study started a monitoring pro- gram on the incidence of coral diseases and syndromes in the reef of Cayo Sombrero. The CARICOMP protocol was used in order to evaluate reef health. Ten parallel band-transects (20 x 2m) where established at two depth intervals: Five between 3-8 m and five between 8-12 m, and the frequency of both, healthy and unhealthy colonies of each coral species was recorded along each band transect. In addition to other sources of coral damage (predation, silta- tion, etc), significant differences in disease incidence between the two depths intervals were tested with a Kruskall- Wallis test. The main problems observed were coral diseases such as yellow band (4,2%), dark spots (1.61%) and white plague-II (1.4%), mainly affecting Montastraea faveolata, M. annularis and Siderastrea siderea. Siltation, af- fecting massive colonies, such as Colpophyllia natans and Diploria strigosa; algae overgrowth, predation, anchor damage, and bleaching. Significant differences were found in the incidence of unhealthy (Kruskall-Wallis, p<0.05) bleached (Kruskall-Wallis, p < 0.05) and colonies affected by siltation (Kruskall-Wallis, p<0.05). More than 60% of the 585 coral colonies surveyed at both depths were found to be healthy, indicating that the Cayo Sombrero reef is still in good conditions compared to other localities in the Park. This study stresses the need to conduct early moni- toring programs that survey coral disease incidence as a source of mortality for this coral reef.

Distribution patterns of the sublittoral epibenthic assemblages on a rocky shoal in the Ligurian Sea (NW Mediterranean)

Acquiring baseline data on highly diverse communities such as coralligenous ones is very valuable in order to determine possible shifts in communities and define strategies for their preservation. Distribution of sciaphilic epibenthic communities belonging to the `coralligene de la roche littorale´ was investigated at 30 photostations from 17 to 24 m depth on a rocky shoal off the island complex in the Gulf of La Spezia (Ligurian Sea, NW Mediterranean). Four communities displayed a sharp zonation: Paramuricea clavata characterised deeper, vertical surfaces, whereas on horizontal and medium inclination, sediment-covered substrata, Leptogorgia sarmentosa , together with Eunicella singularis and Eunicella verrucosa , characterised the upper stratum of the deeper community. Shallow vertical walls were characterised by a facies with sponges and zoantharians, whereas community dominated by large, massive colonies of Pentapora fascialis with a basal stratum of sciaphilic algal species patched with sediment on shallow rocky slopes of medium inclination. Bathymetric distribution of assemblages is influenced by high seawater turbidity (mean annual transparency: 11.9 ± 5.7 m at the western site, 6.2 ± 1.6 m at the eastern site), which induces a shift of the upper limit of distribution of these facies to unusually shallow depths. Quantitative data provide a baseline on the study site that will be useful to understand the influence of not only biotic and abiotic factors, but also mass-mortality events, particularly on these communities characterised by high resilience.

Specific detection of Pasteurella multocida in chickens with fowl cholera and in pig lung tissues using fluorescent rRNA in situ hybridization.

A Pasteurella multocida species-specific oligonucleotide probe, pmhyb449, targeting 16S rRNA was designed and evaluated by whole-cell hybridization against 22 selected reference strains in animal tissues. It differentiated P. multocida from other bacterial species of the families Pasteurellaceae and Enterobacteriaceae and also from divergent species of the order Cytophagales (except biovar 2 strains of Pasteurella avium and Pasteurella canis, which have high 16S rRNA similarity to P. multocida). The potential of the probe for specific identification and differentiation of P. multocida was further detected in formalin-fixed paraffin-embedded lung tissues from experimental fowl cholera in chickens and infections in pigs. In chicken lung tissues P. multocida cells were detected singly, in pairs, as microcolonies, and as massive colonies within air capillaries (septa and lumen), parabronchial septa, and blood vessels (wall and lumen). In pig lung, postmortem-injected P. multocida was detected in the alveoli (lumen and wall), and in both animals the bacterial cells were seen in the bronchi. The results showed that with the oligonucleotide probe pmhyb449, fluorescent in situ hybridization is a suitable and fast method for specific detection of P. multocida in histological formalin-fixed tissues. The test was replicable and reproducible and is recommended as a supplementary test for diagnosis and as a tool in pathogenesis studies of fowl cholera and respiratory tract infections in pigs due to P. multocida.