[Show abstract][Hide abstract] ABSTRACT: Sea level rise and an increased frequency and severity of storm surge events due to climate change are likely to increase the susceptibility of low lying coastal areas to seawater flooding. An integral part of any coastal management strategy throughout European countries is the “do nothing” scenario; this is the benchmark against which putative intervention strategies are evaluated. While the prime concern of a flood defense scheme appraisal often focuses on the sustained financial “benefits” of an intervention, intrinsic to a complete multicriteria analysis is a comprehensive evaluation of the ecological and social consequences of coastal flooding, reflecting the needs of end users and satisfying relevant national and international policies.
An ecological perspective may be usefully employed to examine the impact of the do nothing option on coastal environments (e.g. estuaries, sand dunes and grasslands) and businesses. Although at first sight coastal environmental and business systems appear quite different, they have similarities in that both are vulnerable and susceptible to flood damage or loss and both may be analyzed by employing ecological, adaptive, resilience frameworks. From an ecological perspective many coastal environments are of international conservation importance and provide important ecosystem services including coastal protection, nutrient cycling, carbon sequestration, food production and recreation. Nonetheless, despite their potential vulnerability to coastal flooding, our understanding of the effects of salinity on the biological response of many coastal plants and animals is extremely limited. We show here how plant physiology and patterns of plant and invertebrate distribution are impacted by sea water flooding. We also present responses of model plants to sea water inundation based on the Intergovernmental Panel on Climate Change (IPCC) (2007) predictions of sea level rise and storm surge events. Results showed that coastal habitats surveyed are relatively resilient to flooding due to their species rich nature and their ability to adapt to flooding. However specific groups of plants such as grasses are more affected by flooding and less able to recover.
The socio-economic dimensions of doing nothing are addressed in relation to the impacts of coastal flooding specifically on business activity, which has received little attention to date. Here the focus is on the presence or absence of business disruption and recovery plans as a means of increasing a business's adaptation and resilience to flooding. Results show that some businesses, particularly small ones, are more likely to fail to recover from flooding due to lack of forward planning. Therefore from an ecological perspective business recovery post flooding is likely to be dependent upon ability to adapt, which itself depends upon the construction of resilient business environments.
[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of Sea Research 01/2014; 85:343-348. · 1.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Coastal environments are complex systems undergoing continuous evolution at a range of spatial and temporal scales. In this context, geomorphological and ecological features can be strongly related. We propose a synoptic remote sensing approach to monitor the temporal dynamics of both biotic and abiotic factors in estuarine and coastal ecosystems. Through the combination of spaceborne optical and SAR imagery, we derived both ecological and morphological parameters, to be integrated for a multi-temporal analysis of the dominant processes and trends in coastal landscapes. These dynamics were studied at three locations: Bevano (IT), the Scheldt (B-NL) and Erme (UK). The objectives were to detect and analyze interannual variations of processes and environmental dynamics.
The results highlight that over time, the morphology of different subsystems represents a balance between inputs (forcing agents like tidal range) and natural responses (related responses of the vegetation evolution). As a final remark the calculation of the uncertainties (subsidence rates) using new monitoring techniques such as satellite remote sensing has a specific added value that could be used for simulations over varying time scales and it should be considered as a potential ‘add in’ for an integrated management approach to coastal monitoring and control.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: Abstract Coastal defence structures are proliferating as a result of rising sea levels and stormier seas. With the realisation that most coastal infrastructure cannot be lost or removed, research is required into ways that coastal defence structures can be built to meet engineering requirements, whilst also providing relevant ecosystem services - so-called ecological engineering. This approach requires an understanding of the types of assemblages and their functional roles that are desirable and feasible in these novel ecosystems. We review the major impacts coastal defence structures have on surrounding environments and recent experiments informing building coastal defences in a more ecologically sustainable manner. We summarise research carried out during the THESEUS project (2009-2014) which optimised the design of coastal defence structures with the aim to conserve or restore native species diversity. Native biodiversity could be manipulated on defence structures through various interventions: we created artificial rock pools, pits and crevices on breakwaters; we deployed a precast habitat enhancement unit in a coastal defence scheme; we tested the use of a mixture of stone sizes in gabion baskets; and we gardened native habitat-forming species, such as threatened canopy-forming algae on coastal defence structures. Finally, we outline guidelines and recommendations to provide multiple ecosystem services while maintaining engineering efficacy. This work demonstrated that simple enhancement methods can be cost-effective measures to manage local biodiversity. Care is required, however, in the wholesale implementation of these recommendations without full consideration of the desired effects and overall management goals.
[Show abstract][Hide abstract] ABSTRACT: In a closely integrated system, (sub-) littoral sandy sediments, sandy beaches, and sand dunes offer natural coastal protection for a host of environmentally and economically important areas and activities inland. Flooding and coastal erosion pose a serious threat to these environments, a situation likely to be exacerbated by factors associated with climate change. Despite their importance, these sandy ‘soft’ defences have been lost from many European coasts through the proliferation of coastal development and associated hard-engineering and face further losses due to sea-level rise, subsidence, storm surge events, and coastal squeeze. As part of the EU-funded THESEUS project we investigated the critical drivers that determine the persistence and maintenance of sandy coastal habitats around Europe's coastline, taking particular interest in their close link with the biological communities that inhabit them. The successful management of sandy beaches to restore and sustain sand budgets (e.g. via nourishment), depends on the kind of mitigation undertaken, local beach characteristics, and on the source of ‘borrowed’ sediment. We found that inter-tidal invertebrates were good indicators of changes linked to different mitigation options. For sand dunes, field observations and manipulative experiments investigated different approaches to create new dune systems, in addition to measures employed to improve dune stabilisation. THESEUS provides a ‘toolbox’ of management strategies to aid the management, restoration, and creation of sandy habitats along our coastlines, but we note that future management must consider the connectivity of sub-littoral and supra-littoral sandy habitats in order to use this natural shoreline defence more effectively.
[Show abstract][Hide abstract] ABSTRACT: Microplastics are present in marine habitats worldwide and laboratory studies show this material can be ingested, yet data on abundance in natural populations is limited. This study documents microplastics in 10 species of fish from the English Channel. 504 Fish were examined and plastics found in the gastrointestinal tracts of 36.5%. All five pelagic species and all five demersal species had ingested plastic. Of the 184 fish that had ingested plastic the average number of pieces per fish was 1.90±0.10. A total of 351 pieces of plastic were identified using FT-IR Spectroscopy; polyamide (35.6%) and the semi-synthetic cellulosic material, rayon (57.8%) were most common. There was no significant difference between the abundance of plastic ingested by pelagic and demersal fish. Hence, microplastic ingestion appears to be common, in relatively small quantities, across a range of fish species irrespective of feeding habitat. Further work is needed to establish the potential consequences.
[Show abstract][Hide abstract] ABSTRACT: Estuaries often show clearly recognizable changes in the distribution of organisms along environmental gradients from riverine to fully marine conditions. Surveys performed along the horizontal axis of the Plym and the Yealm Estuaries identified patterns of distribution and abundance of intertidal barnacles and provided a new assessment on the dominance exhibited by the non-native species Elminius modestus in these estuaries. Elminius modestus occurred furthest up in estuaries and was dominant along most of their length, with the exception of few sites closest to the sea; Chthamalus montagui had the most restricted degree of penetration up-estuary; and Semibalanus balanoides occurred at low abundances, with limits of penetration located between those of C. montagui and E. modestus. At many sites, E. modestus was the only barnacle species found. There were changes in the relative abundances of these three species in several particular locations within the Plym and the Yealm in comparison to previous accounts made in the last decades, which, in most cases led to increased dominance of E. modestus. This was mainly due to reductions in the abundances of S. balanoides. Physico-chemical conditions experienced after settlement, especially deposition of silt, exposure and salinity regime contribute to the patterns described here.
[Show abstract][Hide abstract] ABSTRACT: 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 (Forskål) 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 ∼ 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.
Journal of Experimental Marine Biology and Ecology 08/2010; · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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 populations 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 illustrates the strong trophic linkages between the subtidal and intertidal zones, which is likely to be a key factor influencing community structure on European shores.
Marine Ecology Progress Series 01/2010; 406:197-210. · 2.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The crab Necora puber L. is a common predator of limpets, the major grazer on rocky shores in Northern Europe. Information on interactions between crabs and their limpet prey is limited, extending mainly to limpet defensive and predator offensive tactics, while the importance of prey size on the outcome of such interactions remains largely unknown. Here, a laboratory approach was used to test for preference in feeding habits. Predation by N. puber with cheliped height 3 to 27 mm (carapace width [CW]: 16 to 77 mm) was examined on Patella vulgata with shell length 5 to 60 mm. Predator size (10, 11–15, 16–20 and 21–25 mm cheliped height) and prey size (5–10, 15–20, 25–30 and 35–40 mm shell length) were examined, with 2 replicate tests for each predator-prey size combination. Crabs >10 mm in cheliped height (35 mm CW) predominantly crushed the shell of limpets <10 mm, while in the remaining combinations of predator and prey sizes, crabs prised limpets from the substratum. Size of limpet shell (vulnerability to crushing force) and resistance to leverage force were both important factors influencing the outcomes of crab-limpet interactions. For the largest crab tested (27 mm cheliped height; 77 mm CW), there was a size refuge for limpets >41 mm in shell length. Field observations showed that the majority (94%) of limpets present in the intertidal zone are of a size that is vulnerable to predation by N. puber. For all sizes of crab examined, there were clear preferences for limpets smaller than the maximum size that the crabs were actually able to consume. Intriguingly, however, the preference experiment showed that, when given a choice, crabs consistently consumed proportionately more limpets of a larger size-class than when presented only with a single size-class at a time. Although further in situ studies are necessary, the present study indicates that size-selective predation by N. puber and other crabs may have an important influence on limpet population structure.
Marine Ecology Progress Series 01/2010; 416:179-188. · 2.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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 mu m-40 mu m). 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. (C) 2008 Elsevier B.V. All rights reserved.
Journal of Sea Research 04/2009; 61(4):216-221. · 1.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We review how intertidal biodiversity is responding to globally driven climate change, focusing on long-term data from rocky shores in the British Isles. Physical evidence of warming around the British Isles is presented and, whilst there has been considerable fluctuation, sea surface temperatures are at the highest levels recorded, surpassing previous warm periods (i.e. late 1950s). Examples are given of species that have been advancing or retreating polewards over the last 50 to 100 yr. On rocky shores, the extent of poleward movement is idiosyncratic and dependent upon life history characteristics, dispersal capabilities and habitat requirements. More Southern, warm water species have been recorded advancing than northern, cold water species retreating. Models have been developed to predict likely assemblage composition based on future environmental scenarios. We present qualitative and quantitative forecasts to explore the functional consequences of changes in the identity, abundance and species richness of gastropod grazers and foundation species such as barnacles and canopy-forming algae. We forecast. that the balance of primary producers and secondary consumers is likely to change along wave exposure gradients matching changes Occurring with latitude, thereby shifting the balance between export and import of primary production. Increases in grazer and sessile invertebrate diversity are likely to be accompanied by decreasing primary production by large canopy-forming fucoids. The reasons for Such changes are discussed in the context of emerging theory on the relationship between biodiversity and ecosystem functioning.
Marine Ecology Progress Series 01/2009; 396:245-259. · 2.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of Experimental Marine Biology and Ecology 12/2008; · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Journal of Experimental Marine Biology and Ecology. 01/2008;