[Show abstract][Hide abstract] ABSTRACT: Temperate reefs are superb tractable systems for testing hypotheses in ecology and evolutionary biology.
Accordingly there is a rich history of research stretching back over 100 years, which has made major contributions to general ecological and evolutionary theory as well as providing better understanding of how littoral systems work by linking pattern with process. A brief resume´ of the history of temperate reef ecology is provided to celebrate this rich heritage. As a community, temperate reef ecologists generally do well designed experiments and test well formulated hypotheses. Increasingly large datasets are being collected, collated and subjected to complex meta-analyses and used for modelling. These datasets do not happen spontaneously – the burgeoning subject of macroecology is possible only because of the efforts of dedicated natural historians whether it be observing birds, butterflies, or barnacles. High-quality natural history and old-fashioned field craft enable surveys or experiments to be stratified (i.e. replicates are replicates and not a random bit of rock) and lead to the generation of more insightful hypotheses. Modern molecular approaches have led to the discovery of cryptic species and provided phylogeographical insights, but natural history is still required to identify species
in the field. We advocate a blend of modern approaches with old school skills and a fondness for temperate reefs in all their splendour.
Full-text · Article · Aug 2015 · Marine and Freshwater Research
[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.
Full-text · Article · May 2014 · Coastal Engineering
[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.
Full-text · Article · Jan 2014 · Journal of Sea Research
[Show abstract][Hide abstract] ABSTRACT: Existing coastal management and defense approaches are not well suited to meet the challenges of climate change and related uncertanities. Professionals in this field need a more dynamic, systematic and multidisciplinary approach. Written by an international group of experts, Coastal Risk Management in a Changing Climate provides innovative, multidisciplinary best practices for mitigating the effects of climate change on coastal structures. Based on the Theseus program, the book includes eight study sites across Europe, with specific attention to the most vulnerable coastal environments such as deltas, estuaries and wetlands, where many large cities and industrial areas are located. Integrated risk assessment tools for considering the effects of climate change and related uncertainties. Presents latest insights on coastal engineering defenses. Provides integrated guidelines for setting up optimal mitigation measures. Provides directly applicable tools for the design of mitigation measures. Highlights socio-economic perspectives in coastal mitigation.
[Show abstract][Hide abstract] ABSTRACT: Supra-tidal plant communities fulfil a vital role in coastal protection and conservation but despite an increased likelihood of salt-water inundation from storm surges, we understand remarkably little on how salinity affects habitats like coastal grasslands or their component species. We quantified the survival and growth of a common coastal grassland plant, Plantago lanceolata when exposed to short-duration (1-, 2-, 4-, or 8-h) immersion in sea water. We also calculated root:shoot ratios (R:SR) and specific leaf area (SLA) to examine how salinity stress affects above- and below-ground resource allocation patterns and likely interactions with other trophic levels. Immersion in sea water reduced Plantago survival particularly at longer durations of 4- and 8 h, and for surviving plants, growth was also much reduced. Contrary to studies with crop plants however, we found reduced allocation to root biomass (R:SR) and increased SLA. The fact that Plantago displayed opposite ecophysiological responses to those consistently reported in the literature highlights that the response of coastal grassland plants to storm surge events cannot be assumed from conventional wisdom. In order to better protect and conserve these internationally important ecosystems from the effects of anthropogenically induced sea-level rise, a systematic exploration of the effects of sea water flooding on coastal grasslands is required.
No preview · Article · Dec 2013 · Journal of Coastal Conservation
[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.
No preview · Article · Nov 2013 · Coastal Engineering
[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.
Full-text · Article · Jan 2013 · Coastal Engineering
[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.
Full-text · Article · Jan 2013 · Coastal Engineering
[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.
Full-text · Article · Dec 2012 · Marine Pollution Bulletin
[Show abstract][Hide abstract] ABSTRACT: 1. Harvesting green crabs Carcinus maenas for bait is a popular fishery in south-west UK estuaries, which 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.
2. By observing foraging birds in tiled and non-tiled sites we tested the general model that this fishery modified shorebird diversity, distribution and behaviour. We found no evidence for a relationship between shorebird species richness, abundance or assemblage composition and the presence of tiles.
3. To measure distributional and behavioural changes of shorebirds to crab-tiles, we focused 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.
4. 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.
5. 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 to conspecifics in a non-tiled site, though this was dependent on time.
6. We suggest 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 only 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.
[Show abstract][Hide abstract] ABSTRACT: Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal meta-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects-both positive and negative.
Full-text · Article · Jan 2012 · Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences
[Show abstract][Hide abstract] ABSTRACT: Microorganisms are a ubiquitous feature of most hard substrata on Earth and their role in the geomorphological alteration of rock and stone is widely recognized. The role of microorganisms in the modification of engineering materials introduced into the intertidal zone through the construction of hard coastal defences is less well understood. Here we use scanning electron microscopy (SEM) to examine microbial colonization and micro-scale geomorphological features on experimental blocks of limestone, granite and marine concrete after eight months' exposure in the intertidal zone in Cornwall, UK.
Significant differences in the occurrence of microbial growth features, and micro-scale weathering and erosion features were observed between material types (ANOVA p < 0·000). Exposed limestone blocks were characterized by euendolithic borehole erosion (99% occurrence) within the upper 34·0 ± 12·3 µm of the surface. Beneath the zone of boring, inorganic weathering (chemical dissolution and salt action) had occurred to a depth of 125·0 ± 39·0 µm. Boring at the surface of concrete was less common (27% occurrence), while bio-chemical crusting was abundant (94% occurrence, mean thickness 45·1 ± 27·7 µm). Crusts consisted of biological cells, salts and other chemical precipitates. Evidence of cryptoendolithic growth was also observed in limestone and concrete, beneath the upper zone of weathering. On granite, biological activity was restricted to thin epilithic films (<10 µm thickness) with some limited evidence of mechanical breakdown.
Results presented here demonstrate the influence of substratum lithology, hardness and texture on the nature of early micro-scale colonization, and the susceptibility of different engineering materials to organic weathering and erosion processes in the intertidal zone. The implications of differences in initial biogeomorphic responses of materials for long-term rock weathering, ecology and engineering durability are discussed. Copyright
No preview · Article · May 2011 · Earth Surface Processes and Landforms
[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.
No preview · Article · Jan 2011 · Marine Biodiversity Records
[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.
Full-text · Article · Oct 2010 · Marine Ecology Progress Series
[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.
Full-text · Article · Aug 2010 · Journal of Experimental Marine Biology and Ecology
[Show abstract][Hide abstract] ABSTRACT: Harvesting of intertidal invertebrates for use as fishing bait is a global problem for estuary 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 during 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 experimentally 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 proportion 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.
[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.
Full-text · Article · May 2010 · Marine Ecology Progress Series