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This volume presents a representative sample of contributions to the 41st European Marine Biology Symposium held in September 2005 in Cork, Ireland. The theme of the symposium was 'Challenges to Marine Ecosystems' and this was divided into four sub themes, Genetics, Marine Protected Areas, Global Climate Change and Marine Ecosystems, Sustainable Fisheries and Agriculture. The world's marine ecosystems face multiple challenges, some natural, but many resulting from humankind's activities. Global climate change, driven by influences of energy usage and industrial practices, is a reality now accepted by most of the world's scientists, media and political establishments. Warming seas and rising sea levels are regarded as threats, while visionaries consider deep ocean carbon disposal as a technological opportunity. Exploitation of the seas continues apace, with repeated concerns over the impact of over-fishing, plus reservations about the environmental effects of marine aquaculture. We need to understand how resilient organisms and ecosystems are to these challenges, while responding by protecting biologically-meaningful areas of the oceans. The subthemes of the 41st European Marine Biology Symposium address all of these matters.

The recently proposed "Real-Time Incentive (RTI)" fisheries-management approach replaces catch orlandings quotas and days-at-sea limitations with a single allowance of fishing-impact credits ("RTIs"). According to this concept, fishing mortality rates of multiple species and impacts on the ecosystem are regulated through a single "currency". Fishers can fish where and when they want and spend their allocated RTIs according to spatiotemporally varying tariffs. Managers set the tariffs based on agreed target mortality rates of multiple species, using knowledge of the spatiotemporally varying catchabilities of the various species caught or impacted in a mixed fishery. We explore algorithms for combining real-time CPUE data of up to four different species in a conceptual simulation model. The simulations indicate that RTI may perform better than several traditional management systems, such as broad-brush effort restrictions, Total Allowable Catches and Total Allowable Landings, in terms of controlling harvest rates of several species in a mixed fishery with differing catchabilities, while at the same time limiting impact on a vulnerable species or ecosystem elements. Performance weakens with greater spatial overlap of the 'choke' and other species, and also when fish migrate. Real-time updating requires that local CPUE levels in a given time step are predictive of catchabilities in the following time step. Historical information may be more accurate than real-time information if migration patterns are similar year-on-year. RTI allows the fishers to derive the balance between limiting mortality on choke and vulnerable species and optimally exploiting others because it internalises the cost of undesirable outcomes. In the light of the Ecosystem Based Approach to Fisheries Management, and in particular in the context of the European Union landings obligation, the integrated RTI fisheries management approach could offer a practical solution that addresses some of the problems inherent in a multi-objective fishery system. RTI is ready for case-specific testing.

M.N. was funded by a Crawford‐Hayes studentship and National Parks and Wildlife Service (NPWS), Department of Culture, Heritage and Gaeltacht, Ireland. E.D. was supported by the Beaufort Marine Research Award in Fish Population Genetics funded by the Irish Government under the Sea Change Programme. Financial support for A.D.F. was provided by the Welsh Government and Higher Education Funding Council for Wales through the Sêr Cymru National Research Network for Low Carbon, Energy and Environment, and from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska‐Curie grant agreement No. 663830. ; The functioning of marine protected areas (MPAs) designated for marine megafauna has been criticized due to the high mobility and dispersal potential of these taxa. However, dispersal within a network of small MPAs can be beneficial as connectivity can result in increased effective population size, maintain genetic diversity, and increase robustness to ecological and environmental changes making populations less susceptible to stochastic genetic and demographic effects (i.e., Allee effect). Here, we use both genetic and photo-identification methods to quantify gene flow and demographic dispersal between MPAs of a highly mobile marine mammal, the bottlenose dolphin Tursiops truncatus. We identify three populations in the waters of western Ireland, two of which have largely nonoverlapping core coastal home ranges and are each strongly spatially associated with specific MPAs. We find high site fidelity of individuals within each of these two coastal populations to their respective MPA. We also find low levels of demographic dispersal between the populations, but it remains unclear whether any new gametes are exchanged between populations through these migrants (genetic dispersal). The population sampled in the Shannon Estuary has a low estimated effective population size and appears to be genetically isolated. The second coastal population, sampled outside of the Shannon, may be demographically and genetically connected to other coastal subpopulations around the coastal waters of the UK. We therefore recommend that the methods applied here should be used on a broader geographically sampled dataset to better assess this connectivity. ; Publisher PDF ; Peer reviewed