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Plastic pollution has been reported in the North Atlantic Ocean since the 1970s, yet limited data over subsequent decades pose challenges when assessing spatio-temporal trends in relation to global leakages and intervention strategies. This study quantified microplastics within the upper ocean along a longitudinal transect of the North Atlantic and its subtropical gyre. Microplastics were sampled from surface and subsurface (-25 m) water using a manta trawl and NIKSIN bottle respectively. The surface water polymer community varied significantly between geographic positions ('inshore', 'gyre', 'open ocean'), and was significantly influenced by fragment quantity. Compared to other positions, the North Atlantic gyre was associated with high concentrations of polyethylene, polypropylene, acrylic and polyamide fragments. Subsurface water was dominated by polyamide and polyester fibres. Backtracked 2-year Lagrangian simulations illustrated connectivity patterns. Continued monitoring of microplastics throughout the water column of the North Atlantic Ocean is required to address knowledge gaps and assess spatio-temporal trends.

Mechanical interventions are increasingly suggested as a means of removing plastic litter from aquatic environments; their performance is rarely evaluated, but such information is critical to inform policy interventions such as those required to facilitate UNEA 5.2. The Seabin, a fixed-point device designed to remove floating litter in sheltered waters was examined in an urban tidal marina (Southwest UK). It captured on average 58 litter items/day; chiefly plastic pellets, polystyrene balls and plastic fragments. It also captured one marine organism for every 3.6 items of litter, or 13 organisms/day, half of which were dead upon retrieval. The rate of litter capture was inferior to manual cleaning conducted with nets from pontoons or vessels. Hence, in this location the Seabin was of minimal benefit in terms of marine litter removal and resulted in mortality of marine organisms. The presence of such devices could also precipitate false optimism and reliance on technological solutions, rather than systemic changes in our production, use, and disposal of plastics.

Limpets and barnacles are important components of intertidal assemblages worldwide. This study examines the effects of barnacles on the foraging behaviour of the limpetPatella vulgata, which is the main algal grazer in the North-west Atlantic. The behaviour of limpets on a vertical seawall on the Isle of Man (UK) was investigated using autonomous radio-telemetry, comparing their activity patterns on plots characterized by dense barnacle cover and plots from which the barnacles had been removed. Limpet behaviour was investigated at mid-shore level, but two different elevations were considered. This experiment revealed a significant effect of barnacle cover on the activity ofP. vulgata. Limpets on smooth surfaces spent a greater proportion of total time active than did limpets on barnacles. Movement activity was also greater in areas that were lower down in the tidal range. In general, limpets were either predominantly active during diurnal high or nocturnal low tides and always avoided nocturnal high tides. Individuals on barnacles at the higher elevation concentrated their activity during nocturnal low water. All the other groups of limpets (smooth surfaces on the upper level and all individuals on the lower shore) had more excursions centred around daylight hours with an equal distribution of activity between periods of low and high water. Inter-individual variability was, however, pronounced.

In situ studies of plastic deterioration can help us understand the longevity of macroplastic as well as the generation of microplastics in the environment. Photo-oxidation contributing to the generation of microplastics in the marine environment was explored using four types of plastic (polyethene, polystyrene, poly(ethylene terephthalate) and Biothene® exposed in light and in shade, in both air and sea water. Metrics for deterioration were tensile extensibility and oxidation rate. Measurements were conducted at intervals between 7 and 600 days' exposure. Deterioration was faster in air than in sea water and was further accelerated in direct light compared to shade. Extensibility and oxidation were significantly inversely correlated in samples exposed in air. Samples in sea water lost extensibility at a slower rate. Polystyrene, which enters the waste stream rapidly due to its wide application in packaging, deteriorated fastest and is, therefore, likely to form microplastics more rapidly than other materials, especially when exposed to high levels of irradiation, for example when stranded on the shore.

Habitat modification coupled with the spread of non-native species (NNS) are among the top threats to marine biodiversity globally. Species are known to be transported to new locations via international shipping and secondarily spread via regional vessels and artificial structures. Rapid Assessment Surveys (RAS) combining quantitative and semi-quantitative methods compared NNS richness and assemblage composition on intertidal natural rocky shores and artificial structures in harbours in different regions along the south coast of England. Quantitative data showed that artificial habitats supported higher richness than natural habitats, while semi-quantitative data found no difference in richness among habitat types. This result was attributed to additional species found in rock pools during searches of complex microhabitats in natural habitats. Assemblages on artificial structures differed among regions, with regions and harbours with greater numbers of vessels supporting greater richness. Results highlight the importance of shipping and artificial structures for NNS introduction and spread.

Urbanization of coastal habitats is increasing worldwide. However, most man‐made structures are poor surrogates for the habitats they replace and can strongly impact the diversity and functioning of coastal habitats. The value of coastal engineering can be enhanced by the provision of microhabitats that facilitate colonization by marine life. One step forward is moved in this research by combining species coexistence theory, resource patchiness and applied ecology in order to find ways that maximize the biological diversity of coastal defence structures. Featureless areas of a seawall were modified by the addition of microhabitats (resource) that were distributed in different configurations of patchiness. Gastropod diversity peaked at intermediate levels of microhabitat patchiness. This appeared to be driven by different patterns of resource use among species. Gastropods dispersed longer distances on unmodified seawalls than on natural rocky shores, but when microhabitats were added the dispersal decreased. The ability to find microhabitats differed among species. Our results confirm that patchiness in microhabitat distribution affects biodiversity. The extent of microhabitat patchiness could potentially be tailored by coastal engineers to meet specific conservation priorities: increasing diversity versus increasing number of individuals.

Polar oceans, though remote in location, are not immune to the accumulation of plastic debris. The present study, investigated for the first time, the abundance, distribution and composition of microplastics in sub-surface waters of the Arctic Central Basin. Microplastic sampling was carried out using the bow water system of icebreaker Oden (single depth: 8.5 m) and CTD rosette sampler (multiple depths: 8–4369 m). Potential microplastics were isolated and analysed using Fourier Transform Infrared Spectroscopy (FT-IR). Bow water sampling revealed that the median microplastic abundance in near surface waters of the Polar Mixed Layer (PML) was 0.7 particles m−3. Regarding the vertical distribution of microplastics in the ACB, microplastic abundance (particles m−3) in the different water masses was as follows: Polar Mixed Layer (0–375) > Deep and bottom waters (0–104) > Atlantic water (0–95) > Halocline i.e. Atlantic or Pacific (0–83).

While land-based sources of marine plastic pollution have gained widespread attention, marine-based sources are less extensively investigated. Here, we provide the first in-depth description of abandoned, lost or otherwise discarded fishing gear (ALDFG) on northern and southern beaches of the English Southwest Peninsula, Great Britain's region of highest ALDFG density. Three distinct categories were recorded: twisted rope (0.28 ± 0.14 m−1, 17%), braided rope (0.56 ± 0.28 m−1, 33%) and filament (0.84 ± 0.41 m−1, 50%), which likely correspond to fishing rope, net and line. Estimating the disintegration of ALDFG from length and filament number suggests that it has the potential to generate 1277 ± 431 microplastic pieces m−1, with fishing rope (44%) and net (49%) as the largest emitters. Importantly, ALDFG was over five times more abundant on the south coast, which is likely attributable to the three times higher fishing intensity in that area.

Inappropriate disposal of plastic debris has led to the contamination of marine habitats worldwide. This debris can be ingested by organisms; however, the extent to which chewing and gut transit modifies plastic debris is unclear. Detritivores, such as amphipods, ingest and shred natural organic matter and are fundamental to its breakdown. Here we examine ingestion and shredding of plastic carrier bags by Orchestia gammarellus. A laboratory experiment showed these amphipods shredded plastic carrier bags, generating numerous microplastic fragments (average diameter 488.59μm). The presence of a biofilm significantly increased the amount of shredding, but plastic type (conventional, degradable and biodegradable) had no effect. Subsequent field observations confirmed similar shredding occurred on the strandline. Rates of shredding will vary according to amphipod density; however, our data indicates that shredding by organisms could substantially accelerate the formation microplastics in the environment.

Desk-based studies have suggested tyre wear particles contribute a substantial portion of microplastic emissions to the environment, yet few empirical studies report finding tyre wear. Samples were collected from three pathways to the marine environment: atmospheric deposition, treated wastewater effluent, and untreated surface runoff. Pyrolysis coupled to gas chromatography-mass spectrometry was used to detect benzothiazole, a molecular marker for tyres. Benzothiazole was detected in each pathway, emitting tyre wear in addition to other sources of microplastics. Release via surface water drainage was the principle pathway in the regions examined. Laboratory tests indicated larger particles likely settle close to their entry points, whereas smaller particles have potential for longer-range transport and dispersal. The previous lack of reports are likely a consequence of inadequate methods of detection, rather than a low environmental presence. Further work is required to establish distribution, transport potential, and potential impacts once within the marine environment.

Macroalgal canopies are important ecosystem engineers, contributing to coastal productivity and supporting a rich assemblage of associated flora and fauna. However, they are often absent from infrastructures such as coastal defences and there has been a worldwide decline in their distribution in urbanised coastal areas. The macroalga Fucus spiralis is the only high-shore canopy forming species present in the Azores. It is widely distributed in the archipelago but is never found on coastal infrastructures. Here we evaluate factors that may potentially limit its establishment on artificial structures. A number of observational and manipulative experiments were used to test the hypotheses that: (i) limited-dispersal ability limits the colonisation of new plants onto artificial structures, (ii) vertical substratum slope negatively influences the survivorship of recruits, and (iii) vertical substratum slope also negatively influences the survivorship and fitness of adults. Results showed that the limited dispersal from adult plants may be a more important factor than slope in limiting the species ability to colonise coastal infrastructures, since the vertical substratum slope does not affect its fitness or survivorship. European Regional Development Fund (ERDF); COMPETE - Operational Competitiveness Programme; FCT - Foundation for Science and Technology; cE3c funding. GMM was supported by a postdoctoral grant awarded by FCT (SFRH/BDP/63040/2009). ACLP was funded by a FRCT research grant M3.1.5/F/098/2012. Support was also provided by CIRN/UAc (Centre of Natural Resources of University of the Azores). info:eu-repo/semantics/publishedVersion

Plymouth Sound and adjacent estuaries, UK has been used as a working harbour throughout the ages and has a place in maritime history as the port from where the Pilgrim Fathers left for North America in 1620 on the Mayflower and Charles Darwin departed from on the HMS Beagle on his trip to Galapagos in 1831. Today, it remains a working harbour, home to the largest naval base in Western Europe, the host of numerous cruise ships and recreational boats, yet its complex of estuaries (Tamar, Plym, Lynher) and creeks is nationally and internationally recognised as of conservation importance due to its physical characteristics and flora and fauna. Here, we briefly recount the history and importance of Plymouth through the ages in terms of its historic use as a harbour, its marine science heritage and importance on the international stage. We also briefly describe its ecology.

On a global scale, urbanization has resulted in substantial proportions of coasts being replaced by artificial structures such as marinas, breakwaters and seawalls. There is broad consensus that coastal defense structures are poor surrogates of the natural habitats that they replace. Here we investigated the effects of the type and roughness of materials used for the construction of artificial structures on the surrounding biota by comparing abundances and distribution of key inter-tidal taxa between natural shores and coastal defenses. Lower abundances of gastropods and barnacles were found on artificial coastal defense structures (regardless of the material type). At small spatial scales, abundances of key taxa increased with increasing roughness. Our results suggest that the choice of materials used for the construction of coastal defense structures has little effect on community structure per se, but that enhanced roughness could make coastal defenses better surrogates of natural habitats by supporting assemblages that are more similar to those found on natural shores.

Marine litter is a global environmental problem, and working with educators and school students has much potential to facilitate greater public understanding of the solutions and to enable action. This research examined two new educational activities designed to empower European educators and school students to engage with the topic of marine litter, particularly focusing on behavior and on known determinants of behavior rather than knowledge alone. In Study 1, 120 educators participated in an online training course on marine litter, and completed a pre- and post-course questionnaire to assess change. After participating in the course, educators felt significantly more skillful and confident to incorporate marine litter education into their future teaching. In Study 2, 341 school students (7–18 years old) participated in an educational video competition on marine litter, and completed a pre-post questionnaire to assess change. Following the educational activity, students were more concerned about marine litter, had a better understanding of the issue, causes and impacts, and reported performing more waste-reduction behaviors. This research brings together educational and behavioral literatures and demonstrates how educational activities can be documented and evaluated systematically in the quest of tackling marine litter.

There is growing evidence of extensive pollution of the environment by microplastic, with microfibres representing a large proportion of the microplastics seen in marine sediments. Since microfibres are ubiquitous in the environment, present in the laboratory air and water, evaluating microplastic pollution is difficult. Incidental contamination is highly likely unless strict control measures are employed. Here we describe methods developed to minimize the amount of incidental post-sampling contamination when quantifying marine microfibre pollution. We show that our protocol, adapted from the field of forensic fibre examination, reduces fibre abundance by 90% and enables the quick screening of fibre populations. These methods therefore allow an accurate estimate of microplastics polluting marine sediments. In a case study from a series of samples collected on a research vessel, we use these methods to highlight the prevalence of microfibres as marine microplastics.

Marine debris is listed among the major perceived threats to biodiversity, and is cause for particular concern due to its abundance, durability and persistence in the marine environment. An extensive literature search reviewed the current state of knowledge on the effects of marine debris on marine organisms. 340 original publications reported encounters between organisms and marine debris and 693 species. Plastic debris accounted for 92% of encounters between debris and individuals. Numerous direct and indirect consequences were recorded, with the potential for sublethal effects of ingestion an area of considerable uncertainty and concern. Comparison to the IUCN Red List highlighted that at least 17% of species affected by entanglement and ingestion were listed as threatened or near threatened. Hence where marine debris combines with other anthropogenic stressors it may affect populations, trophic interactions and assemblages.

Marine litter is a significant environmental problem inherently linked to individuals’ purchasing, use and disposal behaviour. This research examined 176 British schoolchildren’s (aged 8–13 years) baseline marine litter understanding and self-reported actions, and tested the impact of an educational intervention. All children participated in the educational intervention and completed a pre- and post-intervention questionnaire. At baseline, children were quite concerned about marine litter and recognised some of the causes and impacts of the problem. Children also reported taking a number of actions to help solve the problem. After the intervention, children were significantly more concerned, had a better understanding of the causes and negative impacts, and reported engaging in more actions to reduce the potential causes of marine litter. Understanding the perceptions and behaviours of children is crucial as they represent current and future actors and a potentially important source of social influence among their peers, parents and community.

Antarctica and surrounding waters are often considered pristine, but may be subject to local pollution from tourism, fishing and governmental research programme activities. In particular, the quantification of microplastic pollution within the Antarctic Treaty area (south of latitude 60°S) has received little attention. We examined microplastic particle concentrations in sediment samples from 20 locations up to 7 km from Rothera Research Station. The highest concentrations of microplastic (5 particles 10 ml

Marine litter is a global challenge and society plays an important role via lifestyles and behaviour, including policy support. We analysed public perceptions of marine litter and contributing factors, using data from 1133 respondents across 16 European countries. People reported high levels of concern about marine litter, and the vast majority (95%) reported seeing litter when visiting the coast. The problem was attributed to product and packaging design and behaviour rather than lack of facilities or accidental loss of items. Retailers, industry and government were perceived as most responsible, but also least motivated and competent to reduce marine litter, whereas scientists and environmental groups were perceived as least responsible but most motivated and competent. Regression analyses demonstrated the importance of psychological factors such as values and social norms above socio-demographic variables. These findings are important for communications and interventions to reduce inputs of marine litter to the natural environment.

The acorn barnacle Chthamalus montagui can present strong variation in shell morphology, ranging from flat conic to a highly bent form, caused by a substantial overgrowth of the rostrum plate. Shell shape distribution was investigated between January and May 2004 from geographical to microhabitat spatial scales along the western coast of Britain. Populations studied in the north (Scotland and Isle of Man) showed a higher degree of shell variation compared to those in the south (Wales and south-west England). In the north, C. montagui living at lower tidal levels and in proximity to the predatory dogwhelk, Nucella lapillus, were more bent in profile. Laboratory experiments were conducted to examine behavioural responses, and vulnerability of bent and conic barnacles to predation by N. lapillus. Dogwhelks did not attack one morphotype more than the other, but only 15 % of attacks on bent forms were successful compared to 75 % in conic forms. Dogwhelk effluent reduced the time spent feeding by C. montagui (11 %), but there was no significant difference between conic and bent forms. Examination of barnacle morphology indicated a trade-off in investment in shell structure and feeding appendages associated with being bent, but none with egg or somatic tissue mass. These results are consistent with C. montagui showing an induced defence comparable to that found in its congeners Chthamalus anisopoma and Chthamalus fissus on the Pacific coast of North America, but further work to demonstrate inducibility is required.

The majority of plastic debris found in the marine environment has land based sources and rivers are considered an important medium for transfer of this debris. Here we report on the quantity and composition of floating plastic debris collected from surface waters of the Tamar Estuary. This represents the first study of riverine transport of floating plastic debris into European waters during different tidal regimes. Plastics were found in a variety of forms and sizes and microplastics (

Microplastics represent an increasing source of anthropogenic contamination in aquatic environments, where they may also act as scavengers and transporters of persistent organic pollutants. As estuaries are amongst the most productive aquatic systems, it is important to understand sorption behaviour and transport of persistent organic pollutants (POPs) by microplastics along estuarine gradients. The effects of salinity sorption equilibrium kinetics on the distribution coefficients (Kd) of phenanthrene (Phe) and 4,4′-DDT, onto polyvinyl chloride (PVC) and onto polyethylene (PE) were therefore investigated. A salinity gradient representing freshwater, estuarine and marine conditions, with salinities corresponding to 0 (MilliQ water, 690 μS/cm), 8.8, 17.5, 26.3 and 35 was used. Salinity had no significant effect on the time required to reach equilibrium onto PVC or PE and neither did it affect desorption rates of contaminants from plastics. Although salinity had no effect on sorption capacity of Phe onto plastics, a slight decrease in sorption capacity was observed for DDT with salinity. Salinity had little effect on sorption behaviour and POP/plastic combination was shown to be a more important factor. Transport of Phe and DDT from riverine to brackish and marine waters by plastic is therefore likely to be much more dependent on the aqueous POP concentration than on salinity. The physical characteristics of the polymer and local environmental conditions (e.g. plastic density, particle residence time in estuaries) will affect the physical transport of contaminated plastics. A transport model of POPs by microplastics under estuarine conditions is proposed. Transport of Phe and DDT by PVC and PE from fresh and brackish water toward fully marine conditions was the most likely net direction for contaminant transport and followed the order: Phe-PE >> DDT-PVC = DDT-PE >> Phe-PVC.

Marine environments provide a range of important ecosystem goods and services. To ensure the sustainability of this environment, we require an integrated understanding of the activities taking place in coastal environments that takes into account the benefits to human visitors but also the risks to the environment. This paper presents two studies on the perceived risks and benefits associated with recreational visits to rocky shores in the UK and internationally. Marine experts and recreational users of the coast responded to questionnaires that explored the marine awareness and wellbeing effects of different activities on the visitor and, in turn, the perceived harmfulness of these activities to the environment. Two studies found that a visit to a rocky shore was seen to improve visitors' awareness regarding the marine environment as well as their wellbeing (with some activities being calming such as sunbathing and relaxing, and others exciting such as rock pooling). However, this was perceived to be at a cost to the environment, as some activities were noted to have detrimental effects on the habitat. Marine experts and coastal users gave very similar answers, as did British (Study 1) and international respondents (Study 2). Using an integrative approach, the perceived impacts on both the environment and visitor were then explored together. Walking and rock pooling were seen to provide considerable wellbeing benefits but had high negative impacts on the environment. In contrast, resource focussed activities such as fishing, bait collecting and crabbing were perceived as less important for visitor wellbeing yet also had negative environmental impacts. Using this integrative approach, this analysis begins to suggest priorities for management that benefits both the environment and the recreational users.

Highly mobile predators such as fish and crabs are known to migrate from the subtidal zone to forage in the intertidal zone at high-tide. The extent and variation of these habitat linking movements along the vertical shore gradient have not been examined before for several species simultaneously, hence not accounting for species interactions. Here, the foraging excursions of Carcinus maenas (L.), Necora puber (Linnaeus, 1767) and Cancer pagurus (Linnaeus, 1758) were assessed in a one-year mark-recapture study on two replicated rocky shores in southwest U.K. A comparison between the abundance of individuals present on the shore at high-tide with those present in refuges exposed at low-tide indicated considerable intertidal migration by all species, showing strong linkage between subtidal and intertidal habitats. Estimates of population size based on recapture of marked individuals indicated that an average of ~ 4000 individuals combined for the three crab species, can be present on the shore during one tidal cycle. There was also a high fidelity of individuals and species to particular shore levels. Underlying mechanisms for these spatial patterns such as prey availability and agonistic interactions are discussed. Survival rates were estimated using the Cormack-Jolly-Seber model from multi-recapture analysis and found to be considerably high with a minimum of 30% for all species. Growth rates were found to vary intraspecifically with size and between seasons. Understanding the temporal and spatial variations in predation pressure by crabs on rocky shores is dependent on knowing who, when and how many of these commercially important crab species depend on intertidal foraging. Previous studies have shown that the diet of these species is strongly based on intertidal prey including key species such as limpets; hence intertidal crab migration could be associated with considerable impacts on intertidal assemblages.

Information on past trends is essential to inform future predictions and underpin attribution needed to drive policy responses. It has long been recognised that sustained observations are essential for disentangling climate-driven change from other regional and local-scale anthropogenic impacts and environmental fluctuations or cycles in natural systems. This paper highlights how data rescue and re-use have contributed to the debate on climate change responses of marine biodiversity and ecosystems. It also illustrates via two case studies the re-use of old data to address new policy concerns. The case studies focus on (1) plankton, fish and benthos from the Western English Channel and (2) broad-scale and long-term studies of intertidal species around the British Isles. Case study 1 using the Marine Biological Association of the UK's English Channel data has shown the influence of climatic fluctuations on phenology (migration and breeding patterns) and has also helped to disentangle responses to fishing pressure from those driven by climate, and provided insights into ecosystem-level change in the English Channel. Case study 2 has shown recent range extensions, increases of abundance and changes in phenology (breeding patterns) of southern, warm-water intertidal species in relation to recent rapid climate change and fluctuations in northern and southern barnacle species, enabling modelling and prediction of future states. The case is made for continuing targeted sustained observations and their importance for marine management and policy development.

Microplastics (MPs) are prevalent in marine ecosystems. Because toxicants (termed here “co-contaminants”) can sorb to MPs, there is potential for MPs to alter co-contaminant bioavailability. Our objective was to demonstrate sorption of two co-contaminants with different physicochemistries [phenanthrene (Phe), log10Kow = 4.57; and 17α-ethinylestradiol (EE2), log10Kow = 3.67] to MPs; and assess whether co-contaminant bioavailability was increased after MP settlement. Bioavailability was indicated by gene expression in larval zebrafish. Both Phe and EE2 sorbed to MPs, which reduced bioavailability by a maximum of 33% and 48% respectively. Sorption occurred, but was not consistent with predictions based on co-contaminant physicochemistry (Phe having higher log10Kow was expected to have higher sorption). Contaminated MPs settled to the bottom of the exposures did not lead to increased bioavailability of Phe or EE2. Phe was 48% more bioavailable than predicted by a linear sorption model, organism-based measurements therefore contribute unique insight into MP co-contaminant bioavailability.

Microplastic litter is a pervasive pollutant present in marine systems across the globe. The legacy of microplastics pollution in the marine environment today may remain for years to come due to the persistence of these materials. Microplastics are emerging contaminants of potential concern and as yet there are few recognised approaches for monitoring. In 2008, the EU Marine Strategy Framework Directive (MSFD, 2008/56/EC) included microplastics as an aspect to be measured. Here we outline the approach as discussed by the European Union expert group on marine litter, the technical Subgroup on Marine litter (TSG-ML), with a focus on the implementation of monitoring microplastics in seawater in European seas. It is concluded that harmonization and coherence is needed to achieve reliable monitoring.

Microplastics in the world's oceans are a global concern due to the potential threat they pose to marine organisms. This study investigated microplastic abundance, distribution and composition in the Atlantic Ocean on a transect from the Bay of Biscay to Cape Town, South Africa. Microplastics were sampled from sub-surface waters using the underway system of the RV Polarstern. Potential microplastics were isolated from samples and FT-IR spectroscopy was used to identify polymer types. Of the particles analysed, 63% were rayon and 37% were synthetic polymers. The majority of microplastics were identified as polyesters (49%) and blends of polyamide or acrylic/polyester (43%). Overall, fibres (94%) were predominant. Average microplastic abundance in the Atlantic Ocean was 1.15±1.45particlesm-3. Of the 76 samples, 14 were from the Benguela upwelling and there was no statistically significant difference in microplastic abundance between upwelled and non-upwelled sites.

Microplastics enter the environment as a result of larger plastic items breaking down (‘secondary’) and from particles originally manufactured at that size (‘primary’). Personal care products are an important contributor of secondary microplastics (typically referred to as ‘microbeads’), for example in toothpaste, facial scrubs and soaps. Consumers play an important role in influencing the demand for these products and therefore any associated environmental consequences. Hence we need to understand public perceptions in order to help reduce emissions of microplastics. This study explored awareness of plastic microbeads in personal care products in three groups: environmental activists, trainee beauticians and university students in South West England. Focus groups were run, where participants were shown the quantity of microbeads found in individual high-street personal care products. Qualitative analysis showed that while the environmentalists were originally aware of the issue, it lacked visibility and immediacy for the beauticians and students. Yet when shown the amount of plastic in a range of familiar everyday personal care products, all participants expressed considerable surprise and concern at the quantities and potential impact. Regardless of any perceived level of harm in the environment, the consensus was that their use was unnatural and unnecessary. This research could inform future communications with the public and industry as well as policy initiatives to phase out the use of microbeads.

Washing clothes made from synthetic materials has been identified as a potentially important source of microscopic fibres to the environment. This study examined the release of fibres from polyester, polyester-cotton blend and acrylic fabrics. These fabrics were laundered under various conditions of temperature, detergent and conditioner. Fibres from waste effluent were examined and the mass, abundance and fibre size compared between treatments. Average fibre size ranged between 11.9 and 17.7μm in diameter, and 5.0 and 7.8mm in length. Polyester-cotton fabric consistently shed significantly fewer fibres than either polyester or acrylic. However, fibre release varied according to wash treatment with various complex interactions. We estimate over 700,000 fibres could be released from an average 6kg wash load of acrylic fabric. As fibres have been reported in effluent from sewage treatment plants, our data indicates fibres released by washing of clothing could be an important source of microplastics to aquatic habitats.

Harvesting green crabs Carcinus maenas for bait is a popular fishery in south-west UK estuaries that are important habitats for shorebirds. The fishery involves laying roof tiles or PVC guttering into sediments; crabs seeking refuge bury beneath the tiles and are collected by fishers during low tide. By observing foraging birds in tiled and non-tiled sites the general model that this fishery modified shorebird diversity, distribution, and behaviour was tested. No evidence was found for a relationship between shorebird species richness, abundance or assemblage composition and the presence of tiles. To measure distributional and behavioural changes of shorebirds to crab-tiles, the focus was on two shorebird species: curlew Numenius arquata and redshank Tringa totanus. The crab-tiles affected the shorebird distribution and feeding patterns but this was dependent on species, time, and scale of observation. Redshank spent more time next to tiles than away and dedicated similar feeding effort between treatments. Curlew did not spend proportionally more time next to tiles but did spend more time feeding when they were next to tiles than away from tiles. Curlew and redshank spent proportionally more time probing than pecking when they were next to crab-tiles, but overall spent similar times exhibiting the two feeding behaviours compared with conspecifics in a non-tiled site, although this was dependent on time. It is suggested that crab-tiles may influence the spatial distribution of potential prey, thereby aggregating the birds and relieving predation pressure elsewhere. As both species (curlew and redshank) were observed ‘standing not feeding’, i.e. resting or preening, when next to tiles we also suggest that the structure created by the tiles provides some shelter to reduce negative effects of wind on thermoregulation. Copyright © 2012 John Wiley & Sons, Ltd.

International audience; A key challenge in research linking biodiversity and ecosystem functioning is to incorporate the trophic interactions that characterise natural systems. There is a particular shortage of studies investigating consumer species richness and composition (identity) effects in the context of ecosystem development (or succession). We manipulated the richness and composition of an assemblage of molluscan grazers (Patella ulyssiponensis, Gibbula umbilicalis and Littorina littorea) added to rock pools denuded of existing biota. We created monocultures and all possible multispecies combinations in a substitutive design, and ran a field experiment for 13 mo. We used 2 separate nested analyses to isolate the roles of species richness, species composition nested within levels of species richness and the specific effect of the limpet P. ulyssiponensis, a putative key species. We found no evidence that the biomass or productivity of the developing macroalgal assemblage was affected by grazer richness or species composition nested within richness levels. Rather, the presence of P. ulyssiponensis, irrespective of the presence of other grazer species, acted to suppress mean values of these response variables. Biomass and productivity were not strongly related, showing that they provide unique information on ecosystem functioning in this system. Macroalgal species richness was also reduced by P. ulyssiponensis, and correlated positively with macroalgal biomass, indicating a link between these response variables. Macroalgal species composition was largely insensitive to either species richness or the presence of P. ulyssiponensis, but responded to particular combinations of species within levels of these factors. The key role of P. ulyssiponensis in determining ecosystem functioning is apparent from our results, but we note that consumer species richness may play an important role under more heterogeneous conditions.

There is considerable concern about the hazards that plastic debris presents to wildlife. Use of polymers that degrade more quickly than conventional plastics presents a possible solution to this problem. Here we investigate breakdown of two oxo-biodegradable plastics, compostable plastic and standard polyethylene in the marine environment. Tensile strength of all materials decreased during exposure, but at different rates. Compostable plastic disappeared from our test rig between 16 and 24 weeks whereas approximately 98% of the other plastics remained after 40 weeks. Some plastics require UV light to degrade. Transmittance of UV through oxo-biodegradable and standard polyethylene decreased as a consequence of fouling such that these materials received ∼ 90% less UV light after 40 weeks. Our data indicate that compostable plastics may degrade relatively quickly compared to oxo-biodegradable and conventional plastics. While degradable polymers offer waste management solutions, there are limitations to their effectiveness in reducing hazards associated with plastic debris.

Understanding the effects of predator–prey interactions at a community level requires robust information on the mechanisms determining these interactions at the individual level. Here we use the intertidal crab Eriphia verrucosa (Forskal) as a model species to examine patterns of association between functional morphology (cheliped size and form) and patterns of prey consumption on shores of differing exposure to wave action. The size and form of the cheliped of crabs are known to be related to feeding performance and thus influence the outcomes for prey assemblages. Multivariate analyses showed that the claw size and shape of E. verrucosa varied between shores of differing exposure to wave action. Individuals from exposed locations had larger claws than those from sheltered locations. This shift in size was accompanied by differences in the composition of stomach contents between locations. Crabs from exposed shores had not, vert, similar 55% more hard shell prey (mussels and limpets) in their diet than those from sheltered shores. Crabs were more abundant on sheltered shores, but those from exposed locations were larger in carapace width. The relative abundance of prey varied between shores of differing exposure. Patterns of claw functional morphology provided a mechanistic explanation for the differences in prey consumption along the wave exposure gradient, although it remains to be tested whether there is a phenotypic plasticity response of crab claw to patterns of prey consumption. The interaction between prey abundance and morphology of the cheliped will likely shape the diet of this crab species, and this may have implications for the relative impact of this predator between shores of differing exposure.

Harvesting of intertidal invertebrates for use as fishing bait is a global problem for estu- ary and coastal managers, with significant effects on sediments and associated infauna. Crab-tiling is a method of collection for the shore crab Carcinus maenas, which is then used as angling bait. This fishery operates in estuarine mudflats at a commercial scale, yet its impact on infaunal assemblages has not been quantified. The fishery involves laying hard man-made structures, known as 'crab-tiles', to attract pre-ecdysis C. maenas. Moulting shore crabs are harvested from underneath the tiles dur- ing low tide. Infauna surrounding these tiles, which are important prey for over-wintering wading birds and estuarine fishes, are therefore subjected to disturbance from crab-tiling activity. We exper- imentally manipulated sites on mudflats in 3 previously non-tiled estuaries to determine the impact of crab-tiling on macro-infaunal diversity. In addition to crab-tiled and control plots, treatments were incorporated in order to discriminate between the effects of the tiles and trampling disturbance. Response variables used were sediment penetrability, grain size and organic content as habitat- related variables, and number of taxa and abundance of individual animals as diversity estimators. The effects of crab-tiling on the sediment were contingent on the estuary; those with a greater pro- portion of fine particles were most affected. Simultaneously, crab-tiling reduced diversity (number of taxa and abundance of macro-infauna) and altered assemblage structure. The trampling aspect of crab-tiling was found to have the most impact on the sediment and infauna, and so crab-tiling could be managed via control of access and approaches to minimise sediment disturbance.

Linkages between predators and their prey across the subtidal-intertidal boundary remain relatively unexplored. The influence of tidal phase, tidal height and wave exposure on the abundance, population structure and stomach contents of mobile predatory crabs was examined on rocky shores in southwest Britain. Crabs were sampled both during the day and at night using traps deployed at high tide and by direct observation during low tide. Carcinus maenas (L.), Necora puber (L.) and Cancer pagurus (L.) were the most abundant species, being mainly active during nocturnal high tides. C. maenas was the only species that was active during nocturnal low tides, when it was observed mainly on the lower shore feeding on limpets. Individuals of all 3 species sampled during high tide were considerably larger than those sampled during low tide. Thus, sampling crab popula- tions at low tide is likely to underestimate abundance and the extent of predation by crabs on rocky- shore assemblages. During immersion, the relative abundance of each species was influenced by exposure to wave action and tidal elevation. All species were more abundant on the lower shore; C. maenas and N. puber were more abundant in sheltered locations, while C. pagurus was more abundant in exposed locations. Analyses of stomach contents from individuals captured at high tide revealed that chitons and limpets were the most common hard-shell prey taxa in the diet of these predators. The relative abundance of prey in gut contents was, however, not correlated with patterns of prey abundance. Our study indicates the importance of crabs as key intertidal predators and illus- trates the strong trophic linkages between the subtidal and intertidal zones, which is likely to be a key factor influencing community structure on European shores.

Laying artificial materials on the shore to create refugia that attract crustaceans is a ‘fishing’ technique known mainly from South America and the UK. In the UK, this method of fishing is known as ‘crab-tiling’, which involves laying of roof tiles, pieces of guttering or car tyres (‘crab-tiles’) intertidally in estuaries to provide habitat for Carcinus maenas. Crabs are then harvested for use as angling bait. C. maenas are known to reside under crab-tiles during low tide, however the extent to which crab-tiles influence the distribution and behaviour of crabs and other estuarine fauna during high tide is not clear. To investigate this, fixed underwater video cameras were deployed on a mudflat over two separate occasions in control (non-tiled) and tiled sites. Crabs were significantly more abundant in crab-tiled sites than control sites, and they remained relatively stationary, travelling less in tiled sites than those in control sites. The abundance of mobile fauna (e.g. benthic gobies, mysids, crabs and pelagic fishes) was greater in control sites than in tiled sites during July. The same trend was observed in March but was not significant. Diversity (number of taxa) tended to be greater in control sites than tiled sites on both occasions, but the trend was not significant. The faunal assemblage was not different between control and tiled treatments in either March or July. Crabs occupied crab-tiles throughout high tide immersion, and qualitative observations indicated a tendency to aggressively defend particular tiles. It also seems likely that the tiles provided some protection for the crabs from fish and diving birds.

Little is known about the long-term consequences of grazing effects on microphytes. This study tested for density-dependent responses to grazer removal on the biomass (Chlorophyll a: ‘Chla’) and composition of natural high rocky-shore biofilms over a 7-month period. Gastropod snails Melarhaphe neritoides graze entirely within circular halos generated in biofilms surrounding their refuges. The experiment crossed 3 levels of original snail density per halo with 3 levels of grazing intensity (generated by 100%, 50% and 0% snail removal). Areas inside halos from which all snails had been removed sustained significantly higher Chla than never-grazed control areas outside the halos. This effect of grazing history was still present after 7 months, suggesting that past grazing had an enduring positive influence on biofilm biomass. Against expectation, Chla-biomass was not increased by removing snails, regardless of original grazer density. Half- and fully-grazed halos peaked to a higher Chla than ungrazed halos in spring. Grazing did not affect the presence of major biofilm taxonomic groups, although it did alter their relative contributions. Never-grazed areas were covered by thick biofilm detritus and had proportionally more filamentous cyanobacteria than grazed areas, which sustained abundant clusters of coccoid cyanobacteria and lichen within micro-pits inaccessible to snail radulae. The study shows that effects of grazing history are not exclusive to macrophytic systems. Grazers boosted the concentration of micro-autotrophs relative to non-Chla biofilm constituents, probably by removing an unproductive biofilm canopy and facilitating light and nutrient penetration for new growth.

We review how intertidal biodiversity is responding to globally driven climate change,\ud focusing on long-term data from rocky shores in the British Isles. Physical evidence of warming\ud around the British Isles is presented and, whilst there has been considerable fluctuation, sea surface\ud temperatures are at the highest levels recorded, surpassing previous warm periods (i.e. late 1950s).\ud Examples are given of species that have been advancing or retreating polewards over the last 50 to\ud 100 yr. On rocky shores, the extent of poleward movement is idiosyncratic and dependent upon life\ud history characteristics, dispersal capabilities and habitat requirements. More southern, warm water\ud species have been recorded advancing than northern, cold water species retreating. Models have\ud been developed to predict likely assemblage composition based on future environmental scenarios.\ud We present qualitative and quantitative forecasts to explore the functional consequences of changes\ud in the identity, abundance and species richness of gastropod grazers and foundation species such as\ud barnacles and canopy-forming algae. We forecast that the balance of primary producers and secondary\ud consumers is likely to change along wave exposure gradients matching changes occurring\ud with latitude, thereby shifting the balance between export and import of primary production.\ud Increases in grazer and sessile invertebrate diversity are likely to be accompanied by decreasing\ud primary production by large canopy-forming fucoids. The reasons for such changes are discussed in\ud the context of emerging theory on the relationship between biodiversity and ecosystem functioning.\ud KEY WORDS: Climate change · Intertidal · Range shifts · Biodiversity · Ecosystem functioning ·\ud Northeast Atlantic

Wave action is known to influence the abundance and distribution of intertidal organisms. Wave action will also determine the duration and suitability of various foraging windows (high-tide and low-tide, day and night) for predation and can also affect predator behaviour, both directly by impeding prey handling and indirectly by influencing prey abundance. It remains uncertain whether semi-terrestrial mobile predators such as crabs which can access intertidal prey during emersion when the effects of wave action are minimal, are influenced by exposure. Here, we assessed the effect of wave action on the abundance and population structure (size and gender) of the semi-terrestrial intertidal crab Pachygrapsus marmoratus on rocky shores in Portugal. The activity of P. marmoratus with the tidal cycle on sheltered and exposed shores was established using baited pots at high-tide to examine whether there was activity during intertidal immersion and by low-tide searches. Because prey abundance varies along a wave exposure gradient on most Portuguese shores and because morphology of crab chelipeds are known to be related to diet composition, we further tested the hypothesis that predator stomach contents reflected differences in prey abundance along the horizontal gradient in wave exposure and that this would be correlated with the crab cheliped morphology. Thus, we examined phenotypic variation in P. marmoratus chelipeds across shores of differing exposure to wave action. P. marmoratus was only active during low-tide. Patterns of abundance and population structure of crabs did not vary with exposure to wave action. Stomach contents, however, varied significantly between shores of differing exposure with a higher consumption of hard-shelled prey (mussels) on exposed locations, where this type of prey is more abundant, and a higher consumption of barnacles on sheltered shores. Multivariate geometric analysis of crab claws showed that claws were significantly larger on exposed shores. There was a significant correlation between animals with larger claws and the abundance of mussels in their stomach. Variation in cheliped size may have resulted from differing food availability on sheltered and exposed shores.

The efficiency by which communities capture limiting resources may be related to the number of species or functional types competing therein. This is because species use different resources (i.e. complementarity effect) or because species-rich communities include species with extreme functional traits (positive selection effect). We conducted two manipulative studies to separate the effects of functional richness and functional identity on the feeding efficiency (i.e. filtration rate) of suspension-feeding invertebrates growing on vertical surfaces. In addition, one experiment tested whether the density of organisms influences the effect of functional diversity. Monocultures and complete mixtures of functional types were fed with a solution of microalgae of different sizes (6 μm–40 μm). Experiments conducted at two locations, Helgoland and Plymouth, showed that functional identity had far larger effects on filtration rate than richness. Mixtures did not outperform the average monoculture or the best-performing monoculture and this pattern was independent on density. The high efficiency of one of the functional types in consuming most microalgae could have minimised the resource complementarity. The loss or gain of particular species may therefore have a stronger impact on the functioning of epibenthic communities than richness per se.

Differences between rockpool and emergent rock communities are often attributed to their contrasting physical conditions. However, differences in grazing pressure between rockpools and open rock could also exert an important structuring role. Greater densities and/or the lack of tidal constraints on foraging may allow grazing intensity to be greater in rockpools. Here, wax discs were deployed to compare grazing intensity between rockpool and emergent rock habitats at each of three tidal heights on a moderately exposed shore in SW England. Grazing intensity was then examined in relation to herbivore density. Grazing intensity in pools was twice that on emergent rock, despite a lower density of herbivores in the rockpools. Of these herbivores, patellid limpets are the dominant grazers on rocky shores throughout the NE Atlantic and are recognised to have a major role in structuring intertidal communities. Thus, subsequent experiments focussed on the influence of limpets in determining the differences in consumer pressure between rockpools and emergent rock. Three alternative explanations were considered: (1) the effect of continuous immersion on grazing intensity in rockpools; (2) differences in limpet species abundance between the two habitats; (3) movement of limpets from emergent rock into pools to feed. The level of grazing pressure exerted by Patella ulyssiponensis (Gmelin), the predominant species living constantly immersed in rockpools, was similar to that of P. vulgata (Linnaeus) which is predominantly found on emergent rock. P. vulgata were observed moving from emergent rock into rockpools during high tide. Manipulative experiments confirmed that these foraging excursions resulted in a 2-fold increase in grazing intensity in the pools. Grazing activity of P. vulgata in rockpools was not consistent between sites and may be influenced by differences in wave exposure and/or the abundance of microbial resources. Elevated consumer pressure in rockpools may be an important factor influencing algal assemblages and probably explains the predominance of grazer resistant-species in these pools.

Highly mobile aquatic predators are known to forage in the intertidal during periods of immersion. There is limited quantitative information, however, on the extent to which these predators influence the abundance of grazing molluscs which are known to have a key role in structuring intertidal assemblages. Our preliminary video observations revealed that crabs and small fish were abundant on shores in southwest England during high-tide. We then used manipulative experiments to quantify the effect of small mobile aquatic predators on the abundance of limpets (Patella vulgata L.). On the lower shore at two moderately sheltered rocky shores three treatments were established: complete cage, partial cage (cage control) and uncaged (natural condition). The complete cages excluded all predators. The partial cage treatment allowed full access to small predators and the uncaged treatment allowed access to all predators. After two months, limpet abundance in uncaged and partial cage treatments had declined by around 50% compared to the complete cage treatment. Population structure also changed with survival of larger individuals being greater than smaller individuals in the open and partial cage treatments compared to the complete cage treatment. The effects of excluding predators were consistent at small (meters) and large spatial scales (kilometres) and hence, it would appear that the outcomes of our research are generally applicable to similar shores in the region. To explore the mechanism behind the differential effects of predators according to prey size, we compared the detachment force required to remove limpets of differing sizes from the shore. This was around four times greater for larger individuals than for smaller ones indicating that smaller limpets were more vulnerable to predation. These effects were also consistent between locations. Subsequent laboratory observations showed that the crabs Carcinus maenas (L.), Necora puber (L.) and Cancer pagurus (L.) which are locally abundant predators of limpets, had differing handling behaviour but were all highly efficient at removing limpets from substratum. Hence, shell width and attachment force appeared to be critical factors influencing the vulnerability of limpets to predation by these crabs. Limpets are known to control the abundance of macroalgae on shores in the North-east Atlantic and so our conclusions about the role of mobile predators in regulating the abundance of these grazers are important to our broader understanding of the ecology of these shores.

Collection of marine invertebrates for use as fishing bait is a substantial activity in many parts of the world, often with unknown ecological consequences. As new fisheries develop, it is critical for environmental managers to have high quality ecological information regarding the potential impacts, in order to develop sound management strategies. Crab-tiling is a largely unregulated and un-researched fishery, which operates commercially in the south-west UK. The target species is the green crab Carcinus maenas . Those crabs which are pre-ecdysis and have a carapace width greater than 40 mm are collected to be sold to recreational anglers as bait. Collection involves laying artificial structures on intertidal sandflats and mudflats in estuaries. Crabs use these structures as refugia and are collected during low tide. However, the effect that this fishery has on populations of C. maenas is not known. The impact of crab-tiling on C. maenas population structure was determined by sampling crabs from tiled estuaries and non-tiled estuaries using baited drop-nets. A spatially and temporarily replicated, balanced design was used to compare crab abundance, sizes and sex ratios between estuaries. Typically, fisheries are associated with a reduction in the abundance of the target species. Crab-tiling, however, significantly increased C. maenas abundance. This was thought to be a result of the extra habitat in tiled estuaries, which probably provides protection from natural predators, such as birds and fish. Although crabs were more abundant in tiled estuaries than non-tiled estuaries, the overall percentage of reproductively active crabs in non-tiled estuaries was greater than in tiled estuaries. As with most exploited fisheries stocks, crabs in exploited (tiled) estuaries tended to be smaller, with a modal carapace width of 20–29 mm rather than 30–39 mm in non-tiled estuaries. The sex ratio of crabs however; was not significantly different between tiled and non-tiled estuaries. These results illustrate the potential to manage fished populations using habitat provision to mitigate the effects of fishing pressure.

Increasing levels of eutrophication in coastal waters and recognition of natural variation in supply of nutrients, through for example variations in upwelling intensity, have led to an increasing demand to understand the role of bottom up forcing in coastal communities. Rocky intertidal habitats are highly disturbed and are composed of a patchy mosaic of assemblages in different successional stages. The role of consumer control of algae in such habitats is well recognised but the way consumer control interacts with variation in resource supply is still debated. We examined, using a factorial manipulative experiment, the way top down control by molluscan grazers interacts with nutrient supply to determine the community composition and productivity of early successional communities in intertidal rockpools. The experiment was run over a six-month period, through the summer months, when nutrients were potentially limiting. Rockpools were cleared of biota and nutrient supply enhanced using slow release fertiliser, while the level of molluscan grazing was reduced through regular removals. Macroalgal colonisation was rapid. Positive effects of nutrient enrichment on macroalgal cover were generally lower than the negative effects of grazer control, although at the peak of algal cover, nutrient effects were apparent irrespective of grazer treatment. There were distinct differences in the identity of dominant species among nutrient treatments with green Ulva spp. dominating under enhanced nutrient conditions and red Ceramium spp. dominating under ambient conditions. These differences contributed to a mismatch between effect estimates based on cover and those based on direct measures of productivity. The use of percentage cover as a surrogate of biomass in intertidal studies is discussed. The results indicate that in a disturbed environment enhanced nutrient supply can stimulate macroalgal blooms despite strong top down control by intertidal grazers.

All habitats are modified to some extent by the species that live within them. Kelp is known to have a very strong influence on the surrounding environment providing a habitat for a wide range of organisms including marine mammals, fish and invertebrates. Here we examine the consequences of a subtle shift in the relative abundance of two species of kelp, Laminaria digitata and Laminaria ochroleuca, and compare the holdfast epibiont assemblages on both. These species are morphologically very similar and both provide important biologically generated habitats. The distribution of these kelp species is predicted to alter as a consequence of climate change with L. ochroleuca extending its range northward and potentially outcompeting L. digitata in the north-eastern Atlantic. The epibiont fauna common to both species of kelp were predominantly made up of annelids, molluscs and bryozoans. Most of the epibiont flora we found on the holdfasts was from the class Rhodophyceae. Multivariate analysis showed that the richness of epibiont species associated with L. ochroleuca was significantly lower, a mean of 0.62 species per cm3, when compared to the northern species, L. digitata which had a mean of 1.13 species per cm3. Laminaria digitata also had more unique epibiont species indicating that species richness of holdfast assemblages is likely to decline if L. digitata is replaced by L. ochroleuca. These data illustrate the importance of studying biologically generated habitats when considering the potential consequences of climate change on marine assemblages.

Bioerosion increases the topographic complexity of soft rock habitats, thereby increasingspecies diversity. This increase in species diversity may either be associated with an increase incomplexity or may simply be a consequence of the increase in available surface area for colonisation.The influence of habitat modification by piddocks on intertidal species richness was investigatedthrough field survey using fractal geometry to assess topographical complexity. The relationshipbetween topographical complexity and species diversity was examined using the species spacingtechnique, which uses fractal dimensions to normalise the species richness data in relation to topographicalcomplexity. Six sites were chosen, comprising either clay or chalk substratum, which had arange of rock hardness. Through their rock-boring activities, piddocks significantly increased thetopographical complexity of the shore. Associated with this increase was an increase in species richnessat all sites. Using species spacing, at 5 of the 6 sites, the increased species richness was found tobe area-independent, with more species being observed than would be expected for a simpleincrease in surface area alone. However, piddocks are also known to significantly increase the erosionof soft rock habitats, many of which are regarded as being of particular conservation importancebecause of their rarity within Europe. Piddocks thus increase intertidal biodiversity while at the sametime significantly contributing to erosion of the substratum.

Marine litter is a pervasive and complex societal problem but has no simple solution. Inadequate practices at all levels of production–use–disposal contribute to accumulation of waste on land and at sea. Enhanced societal awareness but also co-responsibility across different sectors and improved interactions between stakeholders are necessary.\ud \ud MARLISCO was a European initiative, which developed and implemented activities across 15 countries. It worked towards raising societal awareness and engagement on marine litter, through a combination of approaches: public exhibitions in over 80 locations; a video competition involving 2100 students; and a legacy of educational and decision-supporting tools. 12 national participatory events designed to facilitate dialogue on solutions brought together 1500 stakeholders and revealed support for cross-cutting, preventive measures. Evaluation during implementation shows that these activities are effective in improving individuals' perceptions about the problem but also commitment in being part of the solution. This paper summarises MARLISCO's approach and highlights a selection of outcomes.

Through their grazing activities limpets have an important role in controlling macroalgal abundance and as a result the structure and dynamics of rocky shore assemblages. Using two congeneric limpet species, with different biogeographic distributions, and whose ranges are expected to alter with climatic warming, we separated the magnitude of their grazing activity over time and the subsequent consequence for macroalgal growth. The northern/boreal limpet, Patella vulgata (L.), consistently grazed more than the southern/lusitanian limpet, P depressa (Pennant), particularly during spring and summer when P depressa was reproductively active. Individuals of Fucus vesiculosus (L.) that settled during this time were able to grow to a size where they escaped the grazing activities of P. depressa, resulting in mature F vesiculosus being present in all P. depressa treatments. In contrast, P vulgata, which was not reproductively active during this period, exhibited no reduction in its grazing activity and prevented macroalgae from growing in experimental treatments. It therefore appears that P. vulgata has a stronger role, than P depressa, in controlling macroalgal abundance on shores of southwest Britain. We present a conceptual model highlighting the direct and indirect interactions between these two limpet species and F. vesiculosis. If as predicted, under current warming scenarios, P depressa becomes the dominant limpet on shores of southwest Britain there will be subsequent changes in rocky shore community structure and ecosystem functioning. Our research emphasises that even closely related species with similar ecological niches can exhibit different behaviours that fundamentally alter their biological interactions with other organisms leading to idiosyncratic responses to predicted changes in climate. (C) 2007 Elsevier B.V All rights reserved.

The distribution of most species is expected to alter in response to climate change. Pre- dictions for the extent of these range shifts are frequently based on 'climate envelope' approaches, which often oversimplify species responses because many do not consider interactions between physical and biological factors. The local persistence of some species, however, is likely to be strongly modulated by microhabitat-forming organisms. Using congeneric patellid gastropods with northern/ boreal and southern/lusitanian distributions, we have demonstrated how the loss of habitat-forming macroalgal species could modify species responses to climate change. The northern limpet Patella vulgata preferentially aggregates beneath Fucus spp. When Fucus vesiculosus was experimentally removed, to simulate a decline in macroalgal abundance in response to climatic warming, P. vulgata suffered increased mortality or relocated home scars, often to nearby Fucus spp. patches. In contrast, the southern limpet P. depressa did not aggregate beneath Fucus spp. and showed no response in terms of movement or mortality to the loss of F. vesiculosus. Based on these results, we predict that the loss of Fucus spp. will influence the relative abundance of these 2 limpet species, particularly at the distributional limit of Fucus spp. In addition, differences in the aggregative behaviour of these limpet species will result in changes in the spatial distribution of grazing in the intertidal, with likely consequences for community dynamics. These outcomes could not be anticipated from predictions based on direct responses to temperature alone, highlighting the need for biotic and abiotic factors to be incorporated into predictions of species responses to climate change.