Covadonga Orejas

First evidence for zooplankton feeding sustaining key physiological processes in a scleractinian cold-water coral

SUMMARY Scleractinian cold-water corals (CWC) represent key taxa controlling deep-sea reef ecosystem functioning by providing structurally complex habitats to a high associated biodiversity, and by fuelling biogeochemical cycles via the release of organic matter. Nevertheless, our current knowledge on basic CWC properties, such as feeding ecology and key physiological processes (i.e. respiration, calcification and organic matter release), is still very limited. Here, we show evidence for the trophic significance of zooplankton, essentially sustaining levels of the investigated key physiological processes in the cosmopolitan CWC Desmophyllum dianthus (Esper 1794). Our results from laboratory studies reveal that withdrawal (for up to 3 weeks) of zooplankton food (i.e. Artemia salina) caused a significant decline in respiration (51%) and calcification (69%) rates compared with zooplankton-fed specimens. Likewise, organic matter release, in terms of total organic carbon (TOC), decreased significantly and eventually indicated TOC net uptake after prolonged zooplankton exclusion. In fed corals, zooplankton provided 1.6 times the daily metabolic C demand, while TOC release represented 7% of zooplankton-derived organic C. These findings highlight zooplankton as a nutritional source for D. dianthus, importantly sustaining respiratory metabolism, growth and organic matter release, with further implications for the role of CWC as deep-sea reef ecosystem engineers.

Feeding strategies and diet composition of four Antarctic cnidarian species

Abstract. The diet of four species of Antarctic cnidarians, two hydroids and two anthozoans, was investigated. One hydroid, Tubularia ralphii, and one anthozoan, Anthomastus bathyproctus, seem to basically consume zooplankton whereas the other hydroid species, Oswaldella antarctica, has a diet mainly based on the fine fraction of seston. The last cnidarian investigated, the stoloniferan alcyonacean, Clavularia cf. frankliniana, feeds mainly on resuspended material. The wide range of diets of these Antarctic cnidarians indicates opportunistic behaviour by feeding on different sources and taking advantage of the available food sources. Data related to low C/N ratios in the sediment and high NO2 concentrations in areas with dense communities of benthic suspension feeders, along with data on capture rates, lead us to hypothesize that these organisms play an important role in the recycling processes of organic matter in Antarctic benthic ecosystems.

Prey capture by a benthic coral reef hydrozoan

Abstract The natural diet and prey abundance of the benthic coral reef hydrozoan Nemalecium lighti, a common tropical species, were studied by analysing the gastrovascular contents of polyps. Prey capture was estimated from 10 samples collected at 3-h intervals during a single diel cycle (1–2 September, 1995) in the San Blas Islands (Panamá). Prey size ranged from 5 to 550 μm, with invertebrate larvae being the main contributor to the diet of the species. Prey items were found in 56–88% of the polyps over the entire diel cycle. Gastrovascular contents varied between 0.93 and 2.13 prey items per polyp. These capture incidences are among the highest reported for cnidarian species. Such rates would allow for high production rates for Nemalecium lighti, consistent with reports of the species’ fast growth and high reproduction rates. The observations suggest that some hydrozoans may be active heterotrophic components in coral reef ecosystems.

Benthos in the Vicinity of Piles: FINO 1 (North Sea)

Changes in the macro-zoobenthic communities in the areas of offshore wind farms are the result of the cumulative effects of numerous piles on the marine fauna. The essential processes take place in the vicinity of these piles. An altered hydrographical regime leads to erosion and to changes in sediment composition in the direct surrounding area of the piles. In addition, the underwater structure provides an artificial hard substrate for many organisms which rarely occur in the typical soft bottom communities of the German Bight. These also influence the food supply for the fauna below and attract predators, which in turn may cause changes of the bottom communities by increasing the predatory pressure. Until very recently, the influence of wind farms on the marine environment could only be estimated theoretically on the basis of the results of investigations of other artificial hard substrates, such as wrecks or artificial reefs. These however represent different structures of different dimensions. Initial results from an offshore wind farm at Horns Rev Denmark, have been presented (ELSAM 2004a, 2004b), but are only partially transferable to the planned installations in the German Bight, since both the hydrographic and the sedimentological conditions are considerably different. The possibilities of investigating these processes directly at the planned wind energy plants are somewhat restricted, for technical and logistical reasons. Process-oriented studies are for these reasons not part of the standard monitoring programme during construction and operation of such installations. The research platform FINO 11 therefore provided an ideal possibility to study these processes in depth at the piles, prior to the actual construction of the wind farms. Within the framework of the BeoFINO2 research project, several studies addressed questions of the possible ecological effects of offshore wind farms (see also chapters 9 and 13). It is hoped that the results can help assure the environmentally compatible construction of the planned offshore wind farms.

The influence of flow velocity and suspended particulate concentration on net prey capture rates by the scleractinian coral Balanophyllia europaea (Scleractinia: Dendrophylliidae)

Balanophyllia europaea is an endemic Mediterranean sublittoral zooxanthellate solitary coral. Given the broad distribution of the species throughout many areas of the Mediterranean surprisingly little is known of preferred habitat niches or susceptibility of the species to environmental change. In this study we investigated in the laboratory the net prey capture rates of the coral achievable under a range of flow velocities (2.5, 5, 7.5 and 15 cm s) and under exposure to different suspended particulate concentrations (0, 7.3 and 170 mg l). In recirculation flumes we simulated both commonly occurring and the occasionally high flow velocities and various suspended particulate concentrations reported from the Gulf of Lions (north-west Mediterranean). We then delivered ca 500 A. salina nauplii l as food (Artemia salina nauplii) to the flumes and monitored net prey capture over time. We found net prey capture rates by the species to be highest under flow velocities of 5 cm s, with 230 mg C coral individual h achieved. The presence or absence of even environmentally high particulate concentrations (up to 170 mg l resuspended seabed material) did not significantly affect the net prey capture rates achieved by the coral polyps. We found that net prey capture in Balanophyllia europaea is not inhibited during periods of heavy particle exposure, as has been observed in other temperate scleractinian corals. Also, flow velocities of ca 5 s appear to be optimal for maximum net prey capture by the species.

Assessing the living and dead proportions of cold-water coral colonies: implications for deep-water Marine Protected Area monitoring in a changing ocean

Coral growth patterns result from an interplay of coral biology and environmental conditions. In this study colony size and proportion of live and dead skeletons in the cold-water coral (CWC) Lophelia pertusa (Linnaeus, 1758) were measured using video footage from Remotely Operated Vehicle (ROV) transects conducted at the inshore Mingulay Reef Complex (MRC) and at the offshore PISCES site (Rockall Bank) in the NE Atlantic. The main goal of this paper was to explore the development of a simple method to quantify coral growth and its potential application as an assessment tool of the health of these remote habitats. Eighteen colonies were selected and whole colony and dead/living layer size were measured. Live to dead layer ratios for each colony were then determined and analysed. The age of each colony was estimated using previously published data. Our paper shows that: (1) two distinct morphotypes can be described: at the MRC, colonies displayed a ‘cauliflower-shaped’ morphotype whereas at the PISCES site, colonies presented a more flattened ‘bush-shaped’ morphotype; (2) living layer size was positively correlated with whole colony size; (3) live to dead layer ratio was negatively correlated to whole colony size; (4) live to dead layer ratio never exceeded 0.27. These results suggest that as a colony develops and its growth rate slows down, the proportion of living polyps in the colony decreases. Furthermore, at least 73% of L. pertusa colonies are composed of exposed dead coral skeleton, vulnerable to ocean acidification and the associated shallowing of the aragonite saturation horizon, with significant implications for future deep-sea reef framework integrity. The clear visual contrast between white/pale living and grey/dark dead portions of the colonies also gives a new way by which they can be visually monitored over time. The increased use of marine autonomous survey vehicles offers an important new platform from which such a surveying technique could be applied to monitor deep-water marine protected areas in the future.

Ophichthids (Ophichthidae: Anguilliformes) within the body cavity of marine fishes: pseudoparasites?

w. isbert, f.e. montero, m. ferna’ ndez, a. lombarte, m. sacanell and c. orejas Instituto de Ciencias del Mar (CSIC), Pg. Maritim de la Barceloneta 37-49, 08003 Barcelona, Spain, Xarxa de Referència i Desenvolupament en Aquicultura (Generalitat de Catalunya), Department of Animal Biology, Plant Biology and Ecology, Autonomous University of Barcelona, Campus Universitari, 08193 Bellaterra, (Cerdanyola del Vallès) Barcelona, Spain, Unidad de Zoologı́a Marina, Instituto Cavanilles de Biodiversidad y Biologı́a Evolutiva, Universidad de Valencia, and Fundación General de la Universidad de Valencia, Confraria de Pescadors Artesanals de l’Estartit, Carrer Ter Vell 22, 17258 l’Estartit, Instituto Español de Oceanografı́a (IEO), Promontorio de San Martı́n s/n, 39004 Santander, Spain

Hydrozoan biology: the view from a workshop

The Hydrozoan Society was founded in 1985 with the aim of promoting all aspects of the study of hydrozoans, from taxonomy, ecology and physiology to molecular biology. Instead of holding meetings with a formal agenda of talks and lectures, the Society has carried out its objectives by organizing workshops, which encourage internal work groups and new collaboration. Conference sessions and round tables are nevertheless an important activity of the Society and are where the most recent research in the field of hydrozoan biology is presented. The 6th Workshop of the Hydrozoan Society was held in June 2007 at Plymouth in collaboration with the Marine Biological Association of the United Kingdom. It followed the same philosophy as before and as usual the working atmosphere was very open and enthusiastic, making it easy for young scientists to collaborate with more experienced researchers. This propitious environment has always been a key factor in the Society’s activities (Boero, 2007) and it has distilled into one of its best legacies. The Society does not have an official consolidated structure, since it is the work of researchers during and between the workshops that gives it direction and consistency. In addition, although the structure is not very rigid, this actually promotes collaboration and the participation of specialists in joint projects and other activities. Like previous meetings, the Plymouth Workshop hosted a wide range of themes related to the biology of hydrozoans (Mills et al., 2000). The diversity of the work presented, however, was even broader than hitherto. The scientific community has evolved to such an extent that, although basic research on taxonomy and ecology continues hydrozoans also offer a resource increasingly used for studies related to genetics and molecular biology. Papers from this meeting report a bright spectrum of discoveries but do not pretend to include all strands of contemporary research. Many of the authors work at only one remove from live material in the field. Indeed, the Society’s meetings are held within sight of the sea (and where freshwater forms such as hydra are rare). A group of papers on ecology and distribution is full of surprises. The exploration of new habitats, such as the mid-water ecosystems, has led not only to the discovery of new species but also to an understanding of the functions of mid-water habitats and of new aspects of the biology and ecology of their pelagic fauna (Lindsay et al., 2008). The capture of large amounts of phytoplankton and its digestion confirm the omnivorous and also herbivorous feeding of hydroids and hence their significant role in transferring energy from pelagic to benthic ecosystems (Gili et al., 2008). Detailed studies even of highly surveyed areas, such as the Mediterranean, provide unexpected observations concerning unknown species and their life cycles, which demonstrate that even in the best-known areas there is still much to discover (Gravili et al., 2008). This has been the case in the rediscovery of Protohydra leuckarti near Plymouth (Kilvington et al., 2008). The study of colonization processes in species with a patchy distribution has also given unforeseen results, such as asexual reproduction processes not being those which favour aggregation, whereas patchiness in some species is explained by the poor dispersion capacity of larvae with a sexual origin (Marfenin & Belorustseva, 2008). In epiphytic hydrozoan communities, the pattern of biodiversity is related to microhabitat characteristics associated with the algal host’s morphology, on a scale very different from that of environmental processes such as the physical drivers of glacial activities in Arctic communities (Ronowicz et al., 2008). A study of the morphological characteristics of different ecological strategies such as phalanx and guerilla phenotypes in Hydractinia suggests that the traditional view of guerilla growth as an adaptive strategy is no longer correct, and that in several species guerilla-like growth is better seen as poor adaptation (Ferrell, 2008). In populations of tropical hydroids, studies of seasonal variation show that seasonal trends are linked to rainfall and hence to abundant food availability (Di Camillo et al., 2008). Environmental differences in temperature and salinity influence the timing of asexual budding in a hydromedusa (Proboscidactyla) (Kawamura & Kubota, 2008). In bivalve-inhabiting hydroids, the liberation of medusae occurs regularly, and although they are all released at sunset this is not related to a decrease in light intensity (Kubota, 2008a). Hydrozoans which form large colonies, such as the genus Eudendrium, host rich epibiontic organisms that show a highly heterogeneous distribution over the colony as well as some unexpected seasonal patterns (Bavestrello et al., 2008). One of the most complex tasks in the taxonomic study of a phylum such as the Cnidaria is not only to reorganize existing information and situate species correctly according to their

Parasite communities of the white seabream Diplodus sargus sargus in the marine protected area of Medes Islands, north-west Mediterranean Sea

Marine protected areas are considered a useful tool to preserve and recover the biodiversity of ecosystems. It is suggested that fisheries not only affect populations of target and bycatch species but also their parasite communities. Parasites can indicate fishery effects on host species and also on the whole local community, but the effects of fisheries and protection measures on parasite communities are relatively unknown. This study analyses parasite communities of the white seabream Diplodus sargus sargus in order to assess potential effects exerted by protection measures within and by fisheries outside a reserve in the western Mediterranean Sea. This small scale analysis offered the opportunity to study different degrees of fishery effects on parasite infracommunities, without considering climatic effects as an additional factor. Parasite infracommunities of fishes from the no-take zone (NTZ) differed in their composition and structure compared with areas completely or partially open to fisheries. The detected spatial differences in the infracommunities derived from generalist parasites and varied slightly between transmission strategies. Monoxenous parasites were richer and more diverse in both fished areas, but more abundant in the no-take, whereas richness and abundance of heteroxenous parasites were higher for the NTZ. In addition to host body size as one factor explaining these spatial variations, differences within parasite infracommunities between the areas may also be linked to increased host densities and habitat quality since the implementation of the NTZ and its protection measures.

The Builders of the Oceans – Part I: Coral Architecture from the Tropics to the Poles, from the Shallow to the Deep

At any scale, corals are live buildings. Their carbonate skeletons constitute threedimensional frameworks allowing the delicate coral polyp to emerge from the sea bottom and populate vast areas of the ocean. These constructions, reminders of the structural complexity found in the forest, are found everywhere in the Earth’s oceans, from the polar regions to the tropics and from the tidal pools to the dark abyssal plains. They can be found as solitary or in modest aggregations of a few centimeters in size or gargantuan colonies of mythological proportions; when many, they can create the largest nonhuman structures built by organisms. Life and death of the coral “trees” are influenced by the mineral architecture and the presence of bioeroders. Shape and size facilitate or restrict their access to food and C. Orejas (*) Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Baleares, Palma de Mallorca, Spain e-mail: cova.orejas@ba.ieo.es C. Jiménez Energy, Environment and Water Research Center (EEWRC), The Cyprus Institute (CyI), Nicosia, Cyprus Enalia Physis Environmental Research Centre, Nicosia, Cyprus e-mail: c.jimenez@cyi.ac.cy; c.jimenez@enaliaphysis.org.cy # Springer International Publishing AG 2017 S. Rossi (ed.), Marine Animal Forests, DOI 10.1007/978-3-319-17001-5_10-2 1 light and influence structural strength tested by currents and swells. The role that corals play in the oceans defies any attempt at simplification since it transcends the life span of the small polyp, geological time, and ecological space. Long after the polyps are gone, coral skeletons continue to harbor numerous organisms of disparate nature by overgrowing, drilling, and dissolving the carbonates. These chapters are a personal journey into the coral forest of the world’s oceans, with stations along singular aspects of their present and past. Our point of departure is the ecosystem engineering of the coral polyp through the construction of its skeleton, followed by selected examples of human interactions with the “stone from the sea” ( see Chapter “The Builders of the Oceans – Part II: Corals from the Past to the Present (The Stone from the Sea)”