Herbivore diversity improves benthic community resilience to ocean acidification

Ocean acidification is expected to alter a wide range of marine systems, but there is great uncertainty about the outcome because indirect effects are often crucial in ecology. Work at volcanic seeps has shown that major ecological shifts occur due to chronic exposure to acidified seawater. Changes in herbivore densities are often seen and this may interact with direct CO2 effects to determine benthic community structure. Here, an exclusion experiment was used to test effects of herbivory in benthic communities along a pCO2 gradient off Methana (Greece). A manipulative experiment was used to examine how large herbivores affected sublittoral algal communities as seawater carbon dioxide levels increased. Sea urchins and herbivorous fish dramatically reduced macroalgal biomass at background carbon dioxide levels; this effect was not hampered by increased pCO2 despite lower sea urchin densities near the seeps, since herbivorous fish abundances increased concurrently. We found that carbon dioxide levels up to about 2000μatm are unlikely to reduce the role of herbivory in structuring benthic communities if tolerant species are able to replace those that are vulnerable. A shift from sea urchins to fish as main grazers highlights that ocean acidification may cause unexpected responses at the community level, and that maintaining high functional redundancy in marine ecosystems is key to improving their resilience

Dendrophyllia in Greek waters, Mediterranean Sea, with the first record of D. ramea (Cnidaria, Scleractinia) from the area

no abstrac

ECOfast – An integrative ecological evaluation index for an ecosystem-based assessment of shallow rocky reefs

The degradation of marine ecosystems is a growing concern worldwide, emphasizing the need for efficient tools to assess their ecological status. Herein, a novel ecosystem-based ecological evaluation index of shallow rocky reefs is introduced and tested in the Aegean and Ionian Seas (NE Mediterranean). The index focuses on a specific set of pre-selected species, including habitat-forming, key, commercially important, and non-indigenous species, across a wide range of trophic levels (1.00–4.53). Data acquisition is conducted through rapid non-destructive SCUBA diving surveys to assess all macroscopic food web components (macroalgae, invertebrates, and fish). Two versions of the index, ECOfast and ECOfast-NIS, were developed, each applying a different approach to account for the impact of non-indigenous species. In our case study, the correlations between the two versions of the index and sea surface temperature, protection status, occurrence of carnivorous fish, and non-indigenous herbivores were assessed through generalized additive models (GAMs). The assessment assigned 93% (ECOfast) or 96% (ECOfast-NIS) of the sites to a moderate to bad ecological status, indicating an alarming situation in the shallow rocky reefs of the NE Mediterranean. Sites evaluated as poor or bad were characterized by extensive coverage of ephemeral macroalgae, absence or minimal presence of large indigenous carnivorous fish, and complete absence of one to three out of five invertebrate functional trophic groups. The community composition of macroalgae, herbivorous species, and carnivorous fishes differed between the 5 m and 15 m depth zones. Surface temperature and carnivorous fish occurrence were the most important tested predictors of the ecological status of shallow rocky reefs. The best GAMs showed that the ECOfast score declined with sea surface temperature and increased with the occurrence of carnivorous fish; ECOfast-NIS declined with sea surface temperature and the occurrence of non-indigenous fish and increased with the occurrence of carnivorous fish. The non-destructive and integrative nature of this approach, its speed of data acquisition and analysis, and its capacity to account for highly mobile predatory fish and non-indigenous species render the ECOfast index a novel, robust, and valuable tool for assessing the ecological status of shallow rocky reefs

Seasonality affects macroalgal community response to increases in pCO2.

Ocean acidification is expected to alter marine systems, but there is uncertainty about its effects due to the logistical difficulties of testing its large-scale and long-term effects. Responses of biological communities to increases in carbon dioxide can be assessed at CO2 seeps that cause chronic exposure to lower seawater pH over localised areas of seabed. Shifts in macroalgal communities have been described at temperate and tropical pCO2 seeps, but temporal and spatial replication of these observations is needed to strengthen confidence our predictions, especially because very few studies have been replicated between seasons. Here we describe the seawater chemistry and seasonal variability of macroalgal communities at CO2 seeps off Methana (Aegean Sea). Monitoring from 2011 to 2013 showed that seawater pH decreased to levels predicted for the end of this century at the seep site with no confounding gradients in Total Alkalinity, salinity, temperature or wave exposure. Most nutrient levels were similar along the pH gradient; silicate increased significantly with decreasing pH, but it was not limiting for algal growth at all sites. Metal concentrations in seaweed tissues varied between sites but did not consistently increase with pCO2. Our data on the flora are consistent with results from laboratory experiments and observations at Mediterranean CO2 seep sites in that benthic communities decreased in calcifying algal cover and increased in brown algal cover with increasing pCO2. This differs from the typical macroalgal community response to stress, which is a decrease in perennial brown algae and proliferation of opportunistic green algae. Cystoseira corniculata was more abundant in autumn and Sargassum vulgare in spring, whereas the articulated coralline alga Jania rubens was more abundant at reference sites in autumn. Diversity decreased with increasing CO2 regardless of season. Our results show that benthic community responses to ocean acidification are strongly affected by season

Macroalgal vegetation on a north European artificial reef (Loch Linnhe, Scotland) : biodiversity, community types and role of abiotic factors

Open Access via the Springer Compact Agreement Acknowledgements: We would like to thank the dive team of the UK National Facility for Scientific Diving (NFSD), namely Elaine Azzopardi and Hugh Brown, as well as Norman Smith, skipper of the RV Seol Mara, for their diving and logistics support during the fieldwork for this study in July 2014. Funding information: This study received support from the European Community research infrastructure action under the FP7 ‘capacities’specific program ASSEMBLE (grant no. 227788). Also, the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland, funded by the Scottish Funding Council and contributing institutions; grant reference HR09011) supported FCK and the UK Natural Environment Research Council (NERC) funded NFSD. Funding for the construction of the artificial reefs was provided kindly by Foster Yeoman Limited.Peer reviewedPublisher PD

Assessment of goods and services, vulnerability, and conservation status of European seabed biotopes: a stepping stone towards ecosystem-based marine spatial management

The goal of ecosystem-based marine spatial management is to maintain marine ecosystems in a healthy, productive and resilient condition; hence, they can sustainably provide the needed goods and services for human welfare. However, the increasing pressures upon the marine realm threaten marine ecosystems, especially seabed biotopes, and thus a well-planned approach of managing use of marine space is essential to achieve sustainability. The relative value of seabed biotopes, evaluated on the basis of goods and services, is an important starting point for the spatial management of marine areas. Herein, 56 types of European seabed biotopes and their related goods, services, sensitivity issues, and conservation status were compiled, the latter referring to management and protection tools which currently apply for these biotopes at European or international level. Fishing activities, especially by benthic trawls, and marine pollution are the main threats to European seabed biotopes. Increased seawater turbidity, dredged sediment disposal, coastal constructions, biological invasions, mining, extraction of raw materials, shipping-related activities, tourism, hydrocarbon exploration, and even some practices of scientific research, also exert substantial pressure. Although some first steps have been taken to protect the European sea beds through international agreements and European and national legislation, a finer scale of classification and assessment of marine biotopes is considered crucial in shaping sound priorities and management guidelines towards the effective conservation and sustainability of European marine resources

New records of the rare deep-water alga Sebdenia monnardiana (Rhodophyta) and the alien Dictyota cyanoloma (Phaeophyceae ) and the unresolved case of deep-water kelp in the Ionian and Aegean Seas (Greece)

Parts of the macroalgal flora of the eastern Mediterranean remain incompletely known. This applies in particular to the circalittoral communities. This study, based upon 2 cruises in the Ionian and Aegean Seas, surveyed benthic communities from 40 to 150 m depth by remotely-operated vehicle (ROV) with a special focus on detecting communities of the Mediterranean deep-water kelp Laminaria rodriguezii. These were complemented by shallow-water surveys on adjacent coastlines by snorkelling and scuba diving. While no kelp could be detected at any of the sites surveyed, ROV surveys of northern Euboia Island revealed the first east Mediterranean record of Sebdenia monnardiana (Sebdeniales, Rhodophyta). Snorkelling surveys on the coast of southeast Kefalonia yielded the first record of the alien alga Dictyota cyanoloma in Greece. This paper reports rbcL and SSU sequences for Sebdenia monnardiana, and COI for Dictyota cyanoloma.Peer reviewe

MAREA PROJECT : MEDISEH (Mediterranean Sensitive Habitats) specific contract no 2 (SI2.600741)

Based on the following Terms of Reference (TOR) of the content of the European Commission DG MARE request Ares (2011)665688: “Compile information supporting the identification and location of nursery areas (juveniles in their first and, if appropriate, second year of life) and spawning aggregations. This information, which is to be collated and archived in formats adequate for GIS rendering, shall refer to all the demersal and small pelagic species in the Mediterranean included in Appendix VII of Council Regulation (EC) No 199/2008 as well as for the species subject to minimum size (Council Regulation (EC) No 1967/2006-Annex III). In addition, ecological characterisation of these areas, both in terms of biological community (assemblage) and habitats therein, must be provided.” The technical tender form of the Specific Contract 2 (MEDISEH) defined the following objectives: Review of historical and current data on the locations and the status of seagrass beds, coralligenous and mäerl beds in different GSAs (Geographical Sub-Areas amending amending the Resolution GFCM/31/2007/2) all over the Mediterranean basin. Transform the information into a digitilized format within the framework of a geodatabase Review and map of all existing specific Marine Protected Areas (MPAs) in the Mediterranean area as well as areas that are under any form of national or international regulation. Identify and map suitable areas for Posidonia, coralligenous and mäerl communities by developing habitat distribution models at different spatial scales. Review and map all existing information on historical and current data of nurseries and spawning grounds of certain small pelagic (i.e., Engraulis encrasicolus, Sardina pilchardus, Scomber spp., Trachurus spp.) and demersal species (i.e., Aristaeomorpha foliacea, Aristeus antennatus, Merluccius merluccius, Mullus barbatus, Mullus surmuletus, Nephrops norvegicus, Parapenaeus longirostris, Pagellus erythrinus, Galeus melastomus, Raja clavata, Illex coindetti, Eledone cirrosa) that are included in the Data Collection Framework for the Mediterranean and subjected to minimum landing size based on Council Regulation No 1967/2006-Annex II. Analyze existing survey data and apply spatial analysis techniques in order to identify locations that are more likely to be density hot spot areas or are being more suitable for fish nurseries and spawning grounds for Engraulis encrasicolus, Sardina pilchardus, Scomber spp., Trachurus trachurus, Aristaeomorpha foliacea, Aristeus antennatus, Merluccius merluccius, Mullus barbatus, Mullus surmuletus, Nephrops norvegicus, Parapenaeus longirostris, Pagellus erythrinus, Galeus melastomus, Raja clavata, Illex coindetti, Eledone cirrosa These areas will also be characterized from an environmental and ecological perspective upon data availability. Integrate and present the aforementioned information through a Web-based GIS viewer with an associated geo-referenced database that will operate as a consulting tool for spatial management and conservation planning. Following the revision of the knowledge base, to identify gaps and suggest future research priorities. In order to meet these objectives, an expert team was composed within the MAREA Consortium from scientists with established expertise in the different topics required, and working in different areas of the Mediterranean basin. The team formed to execute the project includes the main Institutes of EU countries in the Mediterranean, all having solid reputations in the fields covered. The participating Institutes/Entities operate in the Western, Central and Eastern parts of the Mediterranean basin, and this ensures familiarity with the geographical areas that are related to the specific tendering. Moreover, a large number of scientists outside of the MAREA Consortium collaborated on a volunteer basis with data and other input. Details on the list of experts and external collaborators can be found in each Work Package in the present report. For CV details, check the MAREA expert web-site http://www.mareaproject.net/.peer-reviewe

Seagrass meadows (Posidonia oceanica) distribution and trajectories of change.

Posidonia oceanica meadows are declining at alarming rates due to climate change and human activities. Although P. oceanica is considered the most important and well-studied seagrass species of the Mediterranean Sea, to date there has been a limited effort to combine all the spatial information available and provide a complete distribution of meadows across the basin. The aim of this work is to provide a fine-scale assessment of (i) the current and historical known distribution of P. oceanica, (ii) the total area of meadows and (iii) the magnitude of regressive phenomena in the last decades. The outcomes showed the current spatial distribution of P. oceanica, covering a known area of 1,224,707 ha, and highlighted the lack of relevant data in part of the basin (21,471 linear km of coastline). The estimated regression of meadows amounted to 34% in the last 50 years, showing that this generalised phenomenon had to be mainly ascribed to cumulative effects of multiple local stressors. Our results highlighted the importance of enforcing surveys to assess the status and prioritize areas where cost-effective schemes for threats reduction, capable of reversing present patterns of change and ensuring P. oceanica persistence at Mediterranean scale, could be implemented.This study was supported and financed by the Commission of the European Union (DG MARE) within the MAREA Framework contract (Call for tenders MARE/2009/05_Lot1) through the Specific Project MEDISEH (SI2.600741): Mediterranean Sensitive Habitats, that received 568.996 euro. The opinions expressed are those of the authors of the study only and do not represent the Commission’s official position. The European Commission is thankfully acknowledged.This is the final version of the article. It first appeared from NPG via http://dx.doi.org/10.1038/srep1250