Marine Research Findings of the VECTORS Project

This website provides access to the research results of the VECTORS project, which can be used to support marine management decisions, policies and governance as well as future research and investment. VECTORS was a large scale project that brought together more than 200 expert researchers from 16 different countries. It examined the significant changes taking place in European seas, their causes, and the impacts they will have on society.


All of the publications created as part of the VECTORS project are listed below (latest first).
Please use the search box below to find a publication by title, author(s), year or keyword; the most relevant results will be displayed at the top of the page.

  • Boyes, S.J. and M. Elliott. (2014). Marine legislation – The ultimate ‘horrendogram’: International law, European directives; national implementation. Marine Pollution Bulletin 86(1–2), 39-47. doi:10.1016/j.marpolbul.2014.06.055
    View abstract The EU is a pre-eminent player in sustainable development, adopting more than 200 pieces of legislation that have direct repercussions for marine environmental policy and management. Over five decades, measures have aimed to protect the marine environment by tackling the impact of human activities, but maritime affairs have been dealt with by separate sectoral policies without fully integrating all relevant sectors. Such compartmentalisation has resulted in a patchwork of EU legislation and resultant national legislation leading to a piecemeal approach to marine protection. These are superimposed on international obligations emanating from UN and other bodies and are presented here as complex ‘horrendograms’ showing the complexity across vertical governance. These horrendograms have surprised marine experts despite them acknowledging the many uses and users of the marine environment. Encouragingly since 2000, the evolution in EU policy has progressed to more holistic directives and here we give an overview of this change.
  • Piraino, S., G. Aglieri and L. Martell. (2014). Pelagia benovici sp. nov. (Cnidaria, Scyphozoa): a new jellyfish in the Mediterranean Sea. Zootaxa 7(3794), 455 - 468. doi:10.11646/zootaxa.3794.3.7
    View abstract A bloom of an unknown semaestome jellyfish species was recorded in the North Adriatic Sea from September 2013 to early 2014. Morphological analysis of several specimens showed distinct differences from other known semaestome species in the Mediterranean Sea and unquestionably identified them as belonging to a new pelagiid species within genus Pelagia. The new species is morphologically distinct from P. noctiluca, currently the only recognized valid species in the genus, and from other doubtful Pelagia species recorded from other areas of the world. Molecular analyses of mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S ribosomal DNA genes corroborate its specific distinction from P. noctiluca and other pelagiid taxa, supporting the monophyly of Pelagiidae. Thus, we describe Pelagia benovici sp. nov. Piraino, Aglieri, Scorrano & Boero.
  • Aglieri, G., C. Papetti, L. Zane, G. Milisenda, F. Boero and S. Piraino. (2014). First evidence of inbreeding, relatedness and chaotic genetic patchiness in the holoplanktonic jellyfish Pelagia noctiluca (Scyphozoa, Cnidaria). PLOS ONE 9(6), e99647. doi:10.1371/journal.pone.0099647
    View abstract Genetic drift and non-random mating seldom influence species with large breeding populations and high dispersal potential, characterized by unstructured gene pool and panmixia at a scale lower than the minimum dispersal range of individuals. In the present study, a set of nine microsatellite markers was developed and used to investigate the spatio-temporal genetic patterns of the holoplanktonic jellyfish Pelagia noctiluca (Scyphozoa) in the Southern Tyrrhenian Sea. Homozygote excess was detected at eight loci, and individuals exhibited intra-population relatedness higher than expected by chance in at least three samples. This result was supported by the presence of siblings in at least 5 out 8 samples, 4 of which contained full-sib in addition to half-sib dyads. Having tested and ruled out alternative explanations as null alleles, our results suggest the influence of reproductive and behavioural features in shaping the genetic structure of P. noctiluca, as outcomes of population genetics analyses pointed out. Indeed, the genetic differentiation among populations was globally small but highlighted: a) a spatial genetic patchiness uncorrelated with distance between sampling locations, and b) a significant genetic heterogeneity between samples collected in the same locations in different years. Therefore, despite its extreme dispersal potential, P. noctiluca does not maintain a single homogenous population, but rather these jellyfish appear to have intra-bloom localized recruitment and/or individual cohesiveness, whereby siblings more likely swarm together as a single group and remain close after spawning events. These findings provide the first evidence of family structures and consequent genetic patchiness in a species with highly dispersive potential throughout its whole life cycle, contributing to understanding the patterns of dispersal and connectivity in marine environments.
  • Gloaguen, P., S. Mahévas, E. Rivot, M. Woillez, J. Guitton, Y. Vermard and M.P. Etienne. (2014). An autoregressive model to describe fishing vessel movement and activity. Environmetrics 26, 17-28. doi:10.1002/env.2319;jsessionid=E57C119AF4567CD584489E7E5F916FFC.f02t01
    View abstract The understanding of the dynamics of fishing vessels is of great interest to characterize the spatial distribution of the fishing effort and to define sustainable fishing strategies. It is also a prerequisite for anticipating changes in fishermen's activity in reaction to management rules, economic context, or evolution of exploited resources. Analyzing the trajectories of individual vessels offers promising perspectives to describe the activity during fishing trips. A hidden Markov model with two behavioral states (steaming and fishing) is developed to infer the sequence of non-observed fishing vessel behavior along the vessel trajectory based on Global Positioning System (GPS) records. Conditionally to the behavior, vessel velocity is modeled with an autoregressive process. The model parameters and the sequence of hidden behavioral states are estimated using an expectation–maximization algorithm, coupled with the Viterbi algorithm that captures the most credible joint sequence of hidden states. A simulation approach was performed to assess the influence of contrast between the model parameters and of the path length on the estimation performances. The model was then fitted to four original GPS tracks recorded with a time step of 15 min derived from volunteer fishing vessels operating in the Channel within the IFREMER RECOPESCA project. Results showed that the fishing activity performed influenced the estimates of the velocity process parameters. Results also suggested future inclusion of variables such as tide currents within the ecosystem approach of fisheries. 
  • Nicolas, D., S. Rochette, M. Llope and P. Licandro. (2014). Spatio-temporal variability of the North Sea cod recruitment in relation to temperature and zooplankton. PLOS ONE 9(2), e88447. doi:10.1371/journal.pone.0088447
    View abstract The North Sea cod (Gadus morhua, L.) stock has continuously declined over the past four decades linked with overfishing and climate change. Changes in stock structure due to overfishing have made the stock largely dependent on its recruitment success, which greatly relies on environmental conditions. Here we focus on the spatio-temporal variability of cod recruitment in an effort to detect changes during the critical early life stages. Using International Bottom Trawl Survey (IBTS) data from 1974 to 2011, a major spatio-temporal change in the distribution of cod recruits was identified in the late 1990s, characterized by a pronounced decrease in the central and southeastern North Sea stock. Other minor spatial changes were also recorded in the mid-1980s and early 1990s. We tested whether the observed changes in recruits distribution could be related with direct (i.e. temperature) and/or indirect (i.e. changes in the quantity and quality of zooplankton prey) effects of climate variability. The analyses were based on spatially-resolved time series, i.e. sea surface temperature (SST) from the Hadley Center and zooplankton records from the Continuous Plankton Recorder Survey. We showed that spring SST increase was the main driver for the most recent decrease in cod recruitment. The late 1990s were also characterized by relatively low total zooplankton biomass, particularly of energy-rich zooplankton such as the copepod Calanus finmarchicus, which have further contributed to the decline of North Sea cod recruitment. Long-term spatially-resolved observations were used to produce regional distribution models that could further be used to predict the abundance of North Sea cod recruits based on temperature and zooplankton food availability.
  • Elliott, M., N.D. Cutts and A. Trono. (2014). A typology of marine and estuarine hazards and risks as vectors of change: A review for vulnerable coasts and their management. Ocean and Coastal Management 93, 88-99. doi:10.1016/j.ocecoaman.2014.03.014
    View abstract This paper illustrates a typology of 14 natural and anthropogenic hazards, the evidence for their causes and consequences for society and their role as vectors of change in estuaries, vulnerable coasts and marine areas. It uses hazard as the potential that there will be damage to the natural or human system and so is the product of an event which could occur and the probability of it occurring whereas the degree of risk then relates to the amount of assets, natural or societal, which may be affected. We give long- and short-term and large- and small-scale perspectives showing that the hazards leading to disasters for society will include flooding, erosion and tsunamis. Global examples include the effects of wetland loss and the exacerbation of problems by building on vulnerable coasts. Hence we emphasise the importance of considering hazard and risk on such coasts and consider the tools for assessing and managing the impacts of risk and hazard. These allow policy-makers to determine the consequences for natural and human systems. We separate locally-derived problems from large-scale effects (e.g. climate change, sea-level rise and isostatic rebound); we emphasise that the latter unmanaged exogenic pressures require a response to the consequences rather than the causes whereas within a management area there are endogenic managed pressures in which we address both to causes and consequences. The problems are put into context by assessing hazards and the conflicts between different uses and users and hence the management responses needed. We emphasise that integrated and sustainable management of the hazards and risk requires 10-tenets to be fulfilled.
  • Arula, T., J. Gröger, H. Ojaveer and M. Simm. (2014). Shifts in the spring herring (Clupea harengus membras) larvae and related environment in the eastern Baltic Sea over the past 50 years. PLOS ONE 9(3), e91304. doi:10.1371/journal.pone.0091304
    View abstract Because of the high management relevance, commercial fish related aspects have often been central in marine ecosystem investigations. The iterative shiftogram method was applied to detect occurrence, type and timing of shifts in the single and multivariate time series linked to the spring spawning herring larvae in the Gulf of Riga (Baltic Sea). Altogether nineteen larval herring and related environmental variables were utilized during the period of 1957–2010. All the time series investigated, either single or multivariate, exhibited one or more shifts with variable type and timing. Multivariate shiftogram based on all time series identified two distinct states (1957–1983 and 1992–2010) in studied variables, separated by a smooth transition period lasting almost ten years. The observed shift was mainly related to hydroclimate and not to phenology or biota. Significantly increased variability was found in larval herring and recruitment abundances after the shift. While the shift in hydroclimate (1985–1991) was followed by the shift in phenology (1991–1997), the shift in biota occurred remarkably later (2003). It is likely that the dynamics in biota were affected by other drivers than those investigated in the current paper.
  • Minchin, D. (2014). The invasive brown alga Undaria pinnatifida (Harvey) Suringar, 1873 (Laminariales: Alariaceae), spreads northwards in Europe. BioInvasions Records 3(2), 57-63. doi:10.3391/bir.2014.3.2.01
    View abstract The Asian kelp Undaria pinnatifida (Harvey) Suringar 1873 was found for the first time in Belfast Lough, Northern Ireland during 2012 and was probably established in 2013. This currently is the most northern locality in Europe. The recent expansion around Britain is likely to continue with further colonisation in Ireland and extension to Scotland. Conditions are suitable for colonisation of Celtic, North and perhaps Norwegian Sea coasts, where it is likely to become an important fouling organism on marinas, aquaculture equipment, and other structures. Its preponderance on marina and other pontoons suggests artificial structures are its preferred initial sites of colonisation.
  • Simons, S.L., H. Bartelings, K.G. Hamon, A.J. Kempf, R. Döring and A. Temming. (2014). Integrating stochastic age-structured population dynamics into complex fisheries economic models for management evaluations: the North Sea saithe fishery as a case study. ICES Journal of Marine Science 71(7), 1638-1652. doi:doi:10.1093/icesjms/fsu049
    View abstract There is growing interest in bioeconomic models as tools for understanding pathways of fishery behaviour in order to assess the impact of alternative policies on natural resources. A model system is presented that combines stochastic age-structured population dynamics with complex fisheries economics. Explicitly, the economic response of fleet segments to changes in stock development is analysed by applying observed values and stochastic recruitment. The optimization of net profits determines the fishing effort and the investment and disinvestment behaviour of fleet segments, which, in turn, affect the level of catch rates and discards. This tool was applied to the North Sea saithe fishery, where ICES reevaluated the existing EU-Norway management plan, focusing on biological reference points only. Two scenarios were tested with alternative harvest control rules and then contrasted with one unregulated scenario with no quotas and driven by optimizing the net profit of the whole fleet. The model showed the success of both harvest control rules in rebuilding the stock and the associated costs to the fleets in terms of maximal 21% reduction in net profits, 21% reduction in crew wages and 11% reduction in fleet size in the midterm (2007-2015). In the long term (2022), successful stock recovery coincided with net profits almost equalling that of the unrestricted fishery. The model is highly sensitive to the parameter values but can be used strategically, providing a qualitative understanding of the anticipated relative changes.
  • Tamburello, L., F. Bulleri, D. Balata, L. Benedetti-Cecchi and C. Frid. (2014). The role of overgrazing and anthropogenic disturbance in shaping spatial patterns of distribution of an invasive seaweed. Journal of Applied Ecology, 406-414. doi:10.1111/1365-2664.12199
    View abstract Natural and human-generated disturbances are widely acknowledged as key drivers of biological invasions. Understanding the role of spatial patterns of compounded disturbances in determining invader establishment and spread can enhance the effectiveness of control strategies. Using the framework of 1/f noise models and by means of a field experiment, we evaluated how the simultaneous exposure of Posidonia oceanica meadows to disturbances (namely overgrazing and rhizome uprooting from vessel anchoring) differing in spatial extent and degree of autocorrelation influenced the establishment and spread of the invasive seaweed, Caulerpa racemosa. Effects on invader establishment and spread were evaluated by means of mixed-effect models relating spatial patterns of disturbance and presence or abundance of C. racemosa, quantified through spectral coefficients. The spatial distribution of C. racemosa mimicked that of overgrazing, both variables showing positive autocorrelation. Yet, C. racemosa was unable to disperse from disturbed patches into adjacent intact areas. The uprooting of rhizomes did not promote the establishment of C. racemosa, but magnified (18 times) the proliferation of the exotic seaweed when coupled with overgrazing. Synthesis and applications: Fish overgrazing of Posidonia oceanica lessens the resistance of seagrass beds to invasion by Caulerpa racemosa. Thus, conservation strategies (e.g. marine protected areas) aiming to restore over-exploited fish populations may indirectly enhance the susceptibility of P. oceanica meadows to invasion by C. racemosa. Uprooting of P. oceanica rhizomes, such as that caused by boat anchoring, exacerbates the effects of overgrazing. The anchoring of recreational vessels should be, therefore, strictly regulated in areas characterized by intense grazing of P. oceanica leaves. More generally, our study shows that native herbivores may indirectly facilitate invasion by reducing the resistance of resident plant communities and suggests that sounded strategies for controlling the establishment and spread of invasive species require taking into account the interactive effects of natural and anthropogenic disturbances.
  • Marchal, P., M. Desprez, Y. Vermard and A. Tidd. (2014). How do demersal fishing fleets interact with aggregate extraction in a congested sea? Estuarine, Coastal and Shelf Science 149, 168-177.
    View abstract The effects of the aggregate extraction intensity and the distance to extraction sites on the distribution of fishing effort were investigated for a broad selection of French and English demersal fleets operating in the Eastern English Channel. The most prominent result was that most fleets fishing near to aggregate extraction sites were not deterred by extraction activities. The fishing effort of dredgers and potters could be greater adjacent to marine aggregates sites than elsewhere, and also positively correlated to extraction intensity with a lag of 0-9 months. The distribution of fishing effort of French netters remained consistent over the study period. However, it is of note that the fishing effort of netters has increased substantially in the impacted area of the Dieppe site (where it is correlated to extraction intensity with a lag of 6 months), while slightly decreasing in the intermediate and reference areas. The attraction of fishing fleets is likely due to a local temporary concentration of their main target species. However, knowledge of their life-history characteristics and habitat preferences suggests that some of these species could be particularly vulnerable to aggregate extractions in the longer term.
  • Marchini, A., J.-C. Sorbe, F. Torelli, A. Lodola and A. Occipinti-Ambrogi. (2014). The non-indigenous Paranthura japonica Richardson, 1909 in the Mediterranean Sea: travelling with shellfish? Mediterranean Marine Science 15(3), 545-553.
    View abstract An anthurid isopod, new to the Mediterranean Sea, has recently been observed in samples from three localities along the Italian coast: the Lagoon of Venice (North Adriatic Sea), La Spezia (Ligurian Sea) and Olbia (Sardinia, Tyrrhenian Sea). The specimens collected showed strong affinity to a species originally described from the NW Pacific Ocean: Paranthura japonica Richardson, 1909. The comparison with specimens from the Bay of Arcachon (Atlantic coast of France), where P. japonica had recently been reported as non-indigenous, confirmed the identity of the species. This paper reports on the most relevant morphological details of the Italian specimens, data on the current distribution of the species and a discussion on the pathways responsible for its introduction. The available data suggest that the presence of this Pacific isopod in several regions of coastal Europe might be due to a series of aquaculture-mediated introduction events that occurred during the last decades of the 1900s. Since then, established populations of P. japonica, probably misidentified, remained unnoticed for a long time.
  • Milisenda, G., S. Rosa, V.L. Fuentes, F. Boero, L. Guglielmo, J.E. Purcell and S. Piraino. (2014). Jellyfish as prey: frequency of predation and selective foraging of Boops boops (Vertebrata, Actinopterygii) on the mauve stinger Pelagia noctiluca (Cnidaria, Scyphozoa). PLOS ONE 9(4), e94600. doi:doi:10.1371/journal.pone.0094600
    View abstract In recent years, jellyfish blooms have attracted considerable scientific interest for their potential impacts on human activities and ecosystem functioning, with much attention paid to jellyfish as predators and to gelatinous biomass as a carbon sink. Other than qualitative data and observations, few studies have quantified direct predation of fish on jellyfish to clarify whether they may represent a seasonally abundant food source. Here we estimate predation frequency by the commercially valuable Mediterranean bogue, Boops boops on the mauve stinger jellyfish, Pelagia noctiluca, in the Strait of Messina NE Sicily). A total of 1054 jellyfish were sampled throughout one year to quantify predation by B. boops from bite marks on partially eaten jellyfish and energy density of the jellyfish. Predation by B. boops in summer was almost twice that in winter, and they selectively fed according to medusa gender and body part. Calorimetric analysis and biochemical composition showed that female jellyfish gonads had significantly higher energy content than male gonads due to more lipids and that gonads had six-fold higher energy content than the somatic tissues due to higher lipid and protein concentrations. Energetically, jellyfish gonads represent a highly rewarding food source, largely available to B. boops throughout spring and summer. During the remainder of the year, when gonads were not very evident, fish predation switched towards lessselective foraging on the somatic gelatinous biomass. P. noctiluca, the most abundant jellyfish species in the Mediterranean Sea and a key planktonic predator, may represent not only a nuisance for human leisure activities and a source of mortality for fish eggs and larvae, but also an important resource for fish species of commercial value, such as B. boops.
  • Neumann, V., F.W. Köster, M. Schaber and M. Eero. (2014). Recovery in eastern Baltic cod: is increased recruitment caused by decreased predation on early life stages? ICES Journal of Marine Science 71(6), 1382-1392.
    View abstract Cod (Gadus morhua) recruitment in the eastern Baltic Sea is influenced by predation on early life stages by sprat (Sprattus sprattus) and herring (Clupea harengus), which is considered as one of the mechanisms preventing cod recovery in the 1990s. In the light of improved cod recruitment in the second half of the 2000s, new analyses of stomach content of sprat and herring were conducted, to elucidate the contribution of changes in predation pressure on cod recruitment. Comparison of stomach contents of sprat and herring in 2004-2008 with data from the 1990s showed a similar diet composition in the two periods; however, changes were found in the ichthyoplankton abundance and composition in the diet, indicating reduced predation pressure on cod eggs in the most recent period. The abundance of cod eggs in the field, availability of other prey, and horizontal and vertical overlap between predator and prey were investigated as potential factors influencing cod egg predation.
  • Ojaveer, H., B.S. Galil, S. Gollasch, A. Marchini, D. Minchin, A. Occhipinti Ambrogi and S. Olenin. (2014). Identifying the top issues of marine invasive alien species in Europe. Management of Biological Invasions 5(2), 81-84.
    View abstract Stemming from a recent freshwater invasives conference, Caffrey et al. (2014) identified "the top 20 issues" that relate to invasive alien species (IAS) management in Europe. With a view to complement and balance the issues highlighted in their account, we offer six important additions that relate to the marine environment. These are: preventive measures, concerns of loss of taxonomic expertise and species identity, gaps in the knowledge of certain taxa and regions, inconsistencies of terminology, need for validation of data and the importance of concentrating on pathways, and their vectors, and levels of certainty associated with these routes.
  • Ojaveer, H., B.S. Galil, D. Minchin, S. Olenin, A. Amorim, J. Canning-Clode, P. Chainho, G.H. Copp, S. Gollasch, A. Jelmert, M. Lehtiniemi, C. McKenzie, J. Mikuš, L. Miossec, A. Occhipinti-Ambrogi, M. Pecarevic, J. Pederson, G. Quilez-Badia, J.W.M. Wijsman and A. Zenetos. (2014). Ten recommendations for advancing the assessment and management of non-indigenous species in marine ecosystems. Marine Policy 44, 160-165. doi:10.1016/j.marpol.2013.08.019i
    View abstract The main objective of recent international legislative measures and policies concerning marine ecosystems is to ensure sustainable environmental management to maintain a good status for marine waters, habitats and resources, with the ultimate target of achieving an integrated ecosystem-based approach to management. Because bioinvasions pose significant threats to marine ecosystems and the goods and services these provide, non-indigenous species (NIS) are included in the more recent legislative documents. A major challenge for the scientific community is to translate the principles of the legislative directives into a realistic, integrated ecosystem-based approach and at the same time provide stakeholders with best practices for managing NIS. The aim of this paper, prepared by members of the Working Group on Introductions and Transfers of Marine Organisms (WGITMO) of the International Council for the Exploration of the Sea (ICES), is to provide guidance for the application of NIS related management in the European Union Marine Strategy Framework Directive (MSFD). Ten recommendations, including NIS identification, standardization of sampling and data, indicators, propagule pressure and management issues are considered in this paper. While most of these suggestions were developed to improve the implementation of the MSFD, several may be more widely applicable.
  • Somerfield, P.J., M. Burton and H. Sanderson. (2014). Analyses of sublittoral macrobenthic community change in a marine nature reserve using similarity profiles (SIMPROF). Marine Environmental Research 102, 51-58.
    View abstract Sublittoral macrobenthic communities in the Skomer Marine Nature Reserve (SMNR), Pembrokeshire, Wales, were sampled at 10 stations in 1993, 1996, 1998, 2003, 2007 and 2009 using a Day grab and a 0.5 mm mesh. The time series is analysed using Similarities Profiles (SIMPROF) tests and associated methods. Q-mode analysis using clustering with Type 1 SIMPROF addresses multivariate structure among samples, showing that there is clear structure associated with differences among years. Inverse (rmode) analysis using Type 2 SIMPROF decisively rejects a hypothesis that species are not associated with each other. Clustering of the variables (species) with Type 3 SIMPROF identifies groups of species which covary coherently through the time-series. The time-series is characterised by a dramatic decline in abundances and diversity between the 1993 and 1996 surveys. By 1998 there had been a shift in community composition from the 1993 situation, with different species dominating. Communities had recovered in terms of abundance and species richness, but different species dominated the community. No single factor could be identified which unequivocally explained the dramatic changes observed in the SMNR. Possible causes were the effects of dispersed oil and dispersants from the Sea Empress oil spill in February 1996 and the cessation of dredge-spoil disposal off St Annes Head in 1995, but the most likely cause was severe weather. With many species, and a demonstrable recovery from an impact, communities within the SMNR appear to be diverse and resilient. If attributable to natural storms, the changes observed here indicate that natural variability may be much more important than is generally taken into account in the design of monitoring programmes.
  • Pinnegar, J.K., M.T. Tomczak and J.S. Link. (2014). How to determine the likely indirect food-web consequences of a newly introduced non-native species: A worked example. Ecological Modelling 272(0), 379-387. doi:
    View abstract In this paper we demonstrate through a worked case-study that it is possible to make an assessment of the indirect food-web consequences that might occur as a result of the arrival of a hither-to not observed non-native species. We also explore implications for commercial fisheries catches, through the application of a suite of complimentary ecosystem modelling tools. Fistularia commersonii is a lessepsian migrant (introduced via the Suez Canal) that was first recorded in the Mediterranean in January 2000. It has since spread throughout the basin and has been described as the fastest and farthest spreading lessepsian fish migrant ever recorded'. We have used a Rank Proportion Algorithm (RPA) model to predict the theoretical diet composition of F. commersonii in the Bay of Calvi, Corsica. We did so based on potential prey abundances, as well as morphological and behavioural characteristics of both the prey and this novel predator. The 'predicted' diet composition of F. commersonii derived from the RPA analysis was then used as input to an Ecopath with Ecosim (EwE) model. This model was used to simulate possible consequences of introducing this invasive species, assuming different rates of expansion of F. commersonii populations in the region. Increases in the F. commersonii population resulted in a marked decline in certain prey types (notably planktivorous fish, Mullus surmuletus and Symphodus tinca). By contrast, seabirds and piscivorous fish were suggested as possible beneficiaries, although this depended heavily on model and scenario assumptions. Overall fisheries catches were projected to increase, and this reflected an anticipated 'bottom up' increase in piscivorous fish that are the main target of the commercial fishery in the Bay of Calvi region.
  • Rivetti, I., S. Fraschetti, P. Lionello, E. Zambianchi and F. Boero. (2014). Global warming and mass mortalities of benthic invertebrates in the Mediterranean Sea. Plos One 9(12), e115655. doi:10.1371/journal.pone.0115655
    View abstract Satellite data show a steady increase, in the last decades, of the surface temperature (upper few millimetres of the water surface) of the Mediterranean Sea. Reports of mass mortalities of benthic marine invertebrates increased in the same period. Some local studies interpreted the two phenomena in a cause-effect fashion. However, a basin-wide picture of temperature changes combined with a systematic assessment on invertebrate mass mortalities was still lacking. Both the thermal structure of the water column in the Mediterranean Sea over the period 1945-2011 and all documented invertebrate mass mortality events in the basin are analysed to ascertain if: 1- documented mass mortalities occurred under conditions of positive temperature trends at basin scale, and 2- atypical thermal conditions were registered at the smaller spatial and temporal scale of mass mortality events. The thermal structure of the shallow water column over the last 67 years was reconstructed using data from three public sources: MEDAR-MEDATLAS, World Ocean Database, MFS-VOS programme. A review of the mass mortality events of benthic invertebrates at Mediterranean scale was also carried out. The analysis of in situ temperature profiles shows that the Mediterranean Sea changed in a nonhomogeneous fashion. The frequency of mass mortalities is increasing. The areas subjected to these events correspond to positive thermal anomalies. Statistically significant temperature trends in the upper layers of the Mediterranean Sea show an increase of up to 0.07°C/yr for a large fraction of the basin. Mass mortalities are consistent with both the temperature increase at basin scale and the thermal changes at local scale, up to 5.2°C. Our research supports the existence of a causal link between positive thermal anomalies and observed invertebrate mass mortalities in the Mediterranean Sea, invoking focused mitigation initiatives in sensitive areas.
  • Pearce, B., J.M. Fariñas-Franco, C. Wilson, J. Pitts, A. deBurgh and P.J. Somerfield. (2014). Repeated mapping of reefs constructed by Sabellaria spinulosa Leuckart 1849 at an offshore wind farm site. Continental Shelf Research 83, 3-13.
    View abstract Sabellaria spinulosa reefs are considered to be sensitive and of high conservation status. This article evaluates the feasibility of using remote sensing technology to delineate S. spinulosa reefs. S. spinulosa reef habitats associated with the Thanet Offshore Windfarm site were mapped using high resolution sidescan sonar (410 kHz) and multibeam echo sounder (<1 m2) data in 2005 (baseline), 2007 (pre-construction baseline) and 2012 (post-construction). The S. spinulosa reefs were identified in the acoustic data as areas of distinct irregular texturing. Maps created using acoustic data were validated using quantitative measures of reef quality, namely tube density (as a proxy for the density of live S. spinulosa), percentage cover of S. spinulosa structures (both living and dead) and associated macrofauna derived from seabed images taken across the development site. Statistically significant differences were observed in all physical measures of S. spinulosa as well the number (S) and diversity (H') of associated species, derived from seabed images classified according to the presence or absence of reef, validating the use of high resolution sidescan sonar to map these important biogenic habitats. High precision mapping in the early stages allowed for the micro-siting of wind turbines in a way that caused minimal damage to S. spinulosa reefs during construction. These habitats have since recovered and expanded in extent. The surveys undertaken at the Thanet Offshore Windfarm site demonstrate the importance of repeat mapping for this emerging industry, allowing habitat enhancement to be attributed to the development whilst preventing background habitat degradation from being wrongly attributed to the development.
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