Alfonso A. Ramos-Esplá

Thermally tolerant corals have limited capacity to acclimatize to future warming

Thermal stress affects organism performance differently depending on the ambient temperature to which they are acclimatized, which varies along latitudinal gradients. This study investigated whether differences in physiological responses to temperature are consistent with regional differences in temperature regimes for the stony coral Oculina patagonica. To resolve this question, we experimentally assessed how colonies originating from four different locations characterized by >3 °C variation in mean maximum annual temperature responded to warming from 20 to 32 °C. We assessed plasticity in symbiont identity, density, and photosynthetic properties, together with changes in host tissue biomass. Results show that, without changes in the type of symbiont hosted by coral colonies, O. patagonica has limited capacity to acclimatize to future warming. We found little evidence of variation in overall thermal tolerance, or in thermal optima, in response to spatial variation in ambient temperature. Given that the invader O. patagonica is a relatively new member of the Mediterranean coral fauna, our results also suggest that coral populations may need to remain isolated for a long period of time for thermal adaptation to potentially take place. Our study indicates that for O. patagonica, mortality associated with thermal stress manifests primarily through tissue breakdown under moderate but prolonged warming (which does not impair symbiont photosynthesis and, therefore, does not lead to bleaching). Consequently, projected global warming is likely to cause repeat incidents of partial and whole colony mortality and might drive a gradual range contraction of Mediterranean corals.

Daily vertical migrations in the epifauna associated with Posidonia oceanica meadows

To estimate the importance of the vertical daily migrations in the structure of the community of the epifauna associated with the leaf stratum of Posidonia oceanica , we compared to the vagil epifauna abundance in respect to the period of the day and the height of the sediment. The study was developed in the P. oceanica meadow of El Campello (Alicante, south-east Spain), during May of 1996, to a depth of 12 m, repeating the samplings in four sites to obtain a correct spatial interpretation. Three main behaviours were detected. Decapods, amphipods, isopods, mysids, ostracods and polychaetes showed a nocturnal increase in the leaf stratum of P. oceanica. By contrast, copepods showed a nocturnal decrease in the leaves and gastropods did not show any temporal change. Chaetognaths and acari did not show statistical differences because of the considerable spatial heterogeneity. These vertical migrations have an extreme importance in the configuration of the structure of the epifauna associated to P. oceanica , in addition to the diverse response of the different taxa.

Artificial Anti-trawling Reefs off Alicante, South- Eastern Iberian Peninsula: Evolution of Reef Block and Set Designs

Many authors and organizations believe that to achieve effective regulation and management of the Mediterranean coastal zone, not only do physical and biological factors have to be considered but also the socio-economic circumstances of the different communities in the area. Doumenge (1981) pointed out that one of the main objectives of such regulation is to preserve fish stocks and so ensure that long-established coastal fishing communities are able to enjoy a sustainable level of catches:‘…it is becoming increasingly difficult to maintain natural fish stocks at a sufficiently high level to ensure a stable base for their future exploitation… these living resources are now in danger of being over- exploited because of an uncontrolled increase in catching-performance as a result of the increase in the number of boats being used, many of which have enormous catch-capacities’. He also pointed out that some effective measures to ensure a future sustainable development of the coastal zone are: ‘…statutory and physical controls to protect the coastal seabed from illegal bottom-trawling which is an environmentally destructive activity comparable to deforestation on land’.

Ammonia-oxidizing Crenarchaeota and nitrification inside the tissue of a colonial ascidian

Marine Crenarchaeota represent an abundant component of the oceanic microbiota that play an important role in the global nitrogen cycle. Here we report the association of the colonial ascidian Cystodytes dellechiajei with putative ammonia-oxidizing Crenarchaeota that could actively be involved in nitrification inside the animal tissue. As shown by 16S rRNA gene analysis, the ascidian-associated Crenarchaeota were phylogenetically related to Nitrosopumilus maritimus, the first marine archaeon isolated in pure culture that grows chemolithoautotrophically oxidizing ammonia to nitrite aerobically. Catalysed reporter deposition (CARD)-FISH revealed that the Crenarchaeota were specifically located inside the tunic tissue of the colony, where moreover the expression of amoA gene was detected. The amoA gene encodes the alpha-subunit of ammonia monooxygenase, which is involved in the first step of nitrification, the oxidation of ammonia to nitrite. Sequencing of amoA gene showed that they were phylogenetically related to amoA genes of N. maritimus and other putative ammonia-oxidizing marine Crenarchaeota. In order to track the suspected nitrification activity inside the ascidian colony under in vivo conditions, microsensor profiles were measured through the tunic tissue. Net NO(x) production was detected in the tunic layer 1200-1800 microm with rates of 58-90 nmol cm(-3) h(-1). Oxygen and pH microsensor profiles showed that the layer of net NO(x) production coincided with O(2) concentrations of 103-116 microM and pH value of 5.2. Together, molecular and microsensor data indicate that Crenarchaeota could oxidize ammonia to nitrite aerobically, and thus be involved in nitrification inside the ascidian tissue.

New insights into Oculina patagonica coral diseases and their associated Vibrio spp. communities

Bleaching of Oculina patagonica has been extensively studied in the Eastern Mediterranean Sea, although no studies have been carried out in the Western basin. In 1996 Vibrio mediterranei was reported as the causative agent of bleaching in O. patagonica but it has not been related to bleached or healthy corals since 2003, suggesting that it was no longer involved in bleaching of O. patagonica. In an attempt to clarify the relationship between Vibrio spp., seawater temperature and coral diseases, as well as to investigate the putative differences between Eastern and Western Mediterranean basins, we have analysed the seasonal patterns of the culturable Vibrio spp. assemblages associated with healthy and diseased O. patagonica colonies. Two sampling points located in the Spanish Mediterranean coast were chosen for this study: Alicante Harbour and the Marine Reserve of Tabarca. A complex and dynamic assemblage of Vibrio spp. was present in O. patagonica along the whole year and under different environmental conditions and coral health status. While some Vibrio spp. were detected all year around in corals, the known pathogens V. mediteranei and V. coralliilyticus were only present in diseased specimens. The pathogenic potential of these bacteria was studied by experimental infection under laboratory conditions. Both vibrios caused diseased signs from 24 °C, being higher and faster at 28 °C. Unexpectedly, the co-inoculation of these two Vibrio species seemed to have a synergistic pathogenic effect over O. patagonica, as disease signs were readily observed at temperatures at which bleaching is not normally observed.

Microcosmus exasperatus (Ascidiacea: Pyuridae), current distribution in the Mediterranean Sea

This work was partly supported by the Scientific Research Projects of Ege University (Project number: 03 SUF 005).

Changes in Fish Assemblages Associated with the Deployment of an Antitrawling Reef in Seagrass Meadows

Abstract Posidonia oceanica seagrass meadows have been degraded in the Mediterranean Sea by trawling. To reduce this impact, antitrawling artificial reefs have been deployed. The introduction of artificial structures on seagrass meadows, however, could potentially change the composition of fishes. Using visual techniques, we examined changes in fish assemblage and density of key species by comparing fish abundances at four seagrass sites with and without artificial reef blocks in El Campello (Alicante), southeastern Spain, between October 1992 and August 1995. The fish assemblage on plots with artificial reefs changed substantially a year after their installation in October 1992. Differences in fish abundance (total counts of 6,692 fish on artificial reefs and 3,565 fish on Posidonia) and in species richness (41 species on artificial reefs and 29 on Posidonia) were found. The abundance of key species were quite different between habitats. Diplodus vulgaris and Chromis chromis were most abundant in all sam...

Structure and temporal dynamics of the bacterial communities associated to microhabitats of the coral Oculina patagonica

Corals are known to contain a diverse microbiota that plays a paramount role in the physiology and health of holobiont. However, few studies have addressed the variability of bacterial communities within the coral host. In this study, bacterial community composition from the mucus, tissue and skeleton of the scleractinian coral Oculina patagonica were investigated seasonally at two locations in the Western Mediterranean Sea, to further understand how environmental conditions and the coral microbiome structure are related. We used denaturing gradient gel electrophoresis in combination with next-generation sequencing and electron microscopy to characterize the bacterial community. The bacterial communities were significantly different among coral compartments, and coral tissue displayed the greatest changes related to environmental conditions and coral health status. Species belonging to the Rhodobacteraceae and Vibrionaceae families form part of O. patagonica tissues core microbiome and may play significant roles in the nitrogen cycle. Furthermore, sequences related to the coral pathogens, Vibrio mediterranei and Vibrio coralliilyticus, were detected not only in bleached corals but also in healthy ones, even during cold months. This fact opens a new view onto unveiling the role of pathogens in the development of coral diseases in the future.

New report of the Antarctic ascidian Corella eumyota (Tunicata: Ascidiacea) on the Galician coast (north-west Spain)

The first record of the non-indigenous Corella eumyota in the Galicia coast (north-west Spain) is reported. One hundred and forty-one specimens of this solitary ascidian were found on soft bottoms at 12 m depth in the inner part of the Ria de Vigo. This is a species from cooler waters of the southern hemisphere and was recorded for the first time in the northern hemisphere in 2002, in France (Lambert, 2004). The specimens have been compared with Antarctic and South American museum samples. Some intraspecific variability was noted.

A massive update of non-indigenous species records in Mediterranean marinas

The Mediterranean Sea is home to over 2/3 of the world’s charter boat traffic and hosts an estimated 1.5 million recreational boats. Studies elsewhere have demonstrated marinas as important hubs for the stepping-stone transfer of non-indigenous species (NIS), but these unique anthropogenic, and typically artificial habitats have largely gone overlooked in the Mediterranean as sources of NIS hot-spots. From April 2015 to November 2016, 34 marinas were sampled across the following Mediterranean countries: Spain, France, Italy, Malta, Greece, Turkey and Cyprus to investigate the NIS presence and richness in the specialized hard substrate material of these marina habitats. All macroinvertebrate taxa were collected and identified. Additionally, fouling samples were collected from approximately 600 boat-hulls from 25 of these marinas to determine if boats host diverse NIS not present in the marina. Here, we present data revealing that Mediterranean marinas indeed act as major hubs for the transfer of marine NIS, and we also provide evidence that recreational boats act as effective vectors of spread. From this wide-ranging geographical study, we report here numerous new NIS records at the basin, subregional, country and locality level. At the basin level, we report three NIS new to the Mediterranean Sea (Achelia sawayai sensu lato, Aorides longimerus, Cymodoce aff. fuscina), and the re-appearance of two NIS previously known but currently considered extinct in the Mediterranean (Bemlos leptocheirus, Saccostrea glomerata). We also compellingly update the distributions of many NIS in the Mediterranean Sea showing some recent spreading; we provide details for 11 new subregional records for NIS (Watersipora arcuata, Hydroides brachyacantha sensu lato and Saccostrea glomerata now present in the Western Mediterranean; Symplegma brakenhielmi, Stenothoe georgiana, Spirobranchus tertaceros sensu lato, Dendostrea folium sensu lato and Parasmittina egyptiaca now present in the Central Mediterranean, and W. arcuata, Bemlos leptocheirus and Dyspanopeus sayi in the Eastern Mediterranean). We also report 51 new NIS country records from recreational marinas: 12 for Malta, 10 for Cyprus, nine for Greece, six for Spain and France, five for Turkey and three for Italy, representing 32 species. Finally, we report 20 new NIS records (representing 17 species) found on recreational boat-hulls (mobile habitats), not yet found in the same marina, or in most cases, even the country. For each new NIS record, their native origin and global and Mediterranean distributions are provided, along with details of the new record. Additionally, taxonomic characters used for identification and photos of the specimens are also provided. These new NIS records should now be added to the relevant NIS databases compiled by several entities. Records of uncertain identity are also discussed, to assess the probability of valid non-indigenous status.