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Dive into the research topics where Steve Widdicombe is active.

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Featured researches published by Steve Widdicombe.


Biology Letters | 2007

Ocean acidification disrupts induced defences in the intertidal gastropod Littorina littorea

Ruth Bibby; Polly Cleall-Harding; Simon D. Rundle; Steve Widdicombe; John I. Spicer

Carbon dioxide-induced ocean acidification is predicted to have major implications for marine life, but the research focus to date has been on direct effects. We demonstrate that acidified seawater can have indirect biological effects by disrupting the capability of organisms to express induced defences, hence, increasing their vulnerability to predation. The intertidal gastropod Littorina littorea produced thicker shells in the presence of predation (crab) cues but this response was disrupted at low seawater pH. This response was accompanied by a marked depression in metabolic rate (hypometabolism) under the joint stress of high predation risk and reduced pH. However, snails in this treatment apparently compensated for a lack of morphological defence, by increasing their avoidance behaviour, which, in turn, could affect their interactions with other organisms. Together, these findings suggest that biological effects from ocean acidification may be complex and extend beyond simple direct effects.


Fish & Shellfish Immunology | 2011

Immunological function in marine invertebrates: Responses to environmental perturbation

Rob Ellis; Helen Parry; John I. Spicer; Thomas H. Hutchinson; Rk Pipe; Steve Widdicombe

The inception of ecological immunology has led to an increase in the number of studies investigating the impact of environmental stressors on host immune defence mechanisms. This in turn has led to an increased understanding of the importance of invertebrate groups for immunological research. This review discusses the advances made within marine invertebrate ecological immunology over the past decade. By demonstrating the environmental stressors tested, the immune parameters typically investigated, and the species that have received the greatest level of investigation, this review provides a critical assessment of the field of marine invertebrate ecological immunology. In highlighting the methodologies employed within this field, our current inability to understand the true ecological significance of any immune dysfunction caused by environmental stressors is outlined. Additionally, a number of examples are provided in which studies successfully demonstrate a measure of immunocompetence through alterations in disease resistance and organism survival to a realized pathogenic threat. Consequently, this review highlights the potential to advance our current understanding of the ecological and evolutionary significance of environmental stressor related immune dysfunction. Furthermore, the potential for the advancement of our understanding of the immune system of marine invertebrates, through the incorporation of newly emerging and novel molecular techniques, is emphasized.


Journal of Experimental Marine Biology and Ecology | 1999

Small scale patterns in the structure of macrofaunal assemblages of shallow soft sediments

M. A. Kendall; Steve Widdicombe

The spatial scale of local patterns in the fauna of two contrasting shallow water sediment assemblages has been investigated using hierarchical sampling. Replicate samples were taken at separations of 50 cm, 5 m, 50 m and 500 m. No significant differences between samples could be detected on any of these scales in a fine sand assemblage. However, in a heavily bioturbated sandy mud, samples separated by more than 50 m were significantly different from each other. This separation was largely a result of changes in the pattern of dominance among the most abundant species, particularly annelids. In a complimentary set of analyses, animals were regrouped either by higher taxa or by body size. The numerically important annelids and crustaceans showed a pattern of spatial similarity close to the full data set, but that shown by molluscs was clearly distinct. Large bodied animals were also independent of the main pattern while smaller species conformed to it. In the case of the latter, separation of sites at the 50 m scale could be related to patterns of species richness as well as dominance.


Biochemical Society Transactions | 2011

Bioturbation: impact on the marine nitrogen cycle.

Bonnie Laverock; Jack A. Gilbert; Karen Tait; A. Mark Osborn; Steve Widdicombe

Sediments play a key role in the marine nitrogen cycle and can act either as a source or a sink of biologically available (fixed) nitrogen. This cycling is driven by a number of microbial remineralization reactions, many of which occur across the oxic/anoxic interface near the sediment surface. The presence and activity of large burrowing macrofauna (bioturbators) in the sediment can significantly affect these microbial processes by altering the physicochemical properties of the sediment. For example, the building and irrigation of burrows by bioturbators introduces fresh oxygenated water into deeper sediment layers and allows the exchange of solutes between the sediment and water column. Burrows can effectively extend the oxic/anoxic interface into deeper sediment layers, thus providing a unique environment for nitrogen-cycling microbial communities. Recent studies have shown that the abundance and diversity of micro-organisms can be far greater in burrow wall sediment than in the surrounding surface or subsurface sediment; meanwhile, bioturbated sediment supports higher rates of coupled nitrification-denitrification reactions and increased fluxes of ammonium to the water column. In the present paper we discuss the potential for bioturbation to significantly affect marine nitrogen cycling, as well as the molecular techniques used to study microbial nitrogen cycling communities and directions for future study.


The ISME Journal | 2010

Bioturbating shrimp alter the structure and diversity of bacterial communities in coastal marine sediments

Bonnie Laverock; Cindy J. Smith; Karen Tait; A. Mark Osborn; Steve Widdicombe; Jack A. Gilbert

Bioturbation is a key process in coastal sediments, influencing microbially driven cycling of nutrients as well as the physical characteristics of the sediment. However, little is known about the distribution, diversity and function of the microbial communities that inhabit the burrows of infaunal macroorganisms. In this study, terminal-restriction fragment length polymorphism analysis was used to investigate variation in the structure of bacterial communities in sediment bioturbated by the burrowing shrimp Upogebia deltaura or Callianassa subterranea. Analyses of 229 sediment samples revealed significant differences between bacterial communities inhabiting shrimp burrows and those inhabiting ambient surface and subsurface sediments. Bacterial communities in burrows from both shrimp species were more similar to those in surface-ambient than subsurface-ambient sediment (R=0.258, P<0.001). The presence of shrimp was also associated with changes in bacterial community structure in surrounding surface sediment, when compared with sediments uninhabited by shrimp. Bacterial community structure varied with burrow depth, and also between individual burrows, suggesting that the shrimps burrow construction, irrigation and maintenance behaviour affect the distribution of bacteria within shrimp burrows. Subsequent sequence analysis of bacterial 16S rRNA genes from surface sediments revealed differences in the relative abundance of bacterial taxa between shrimp-inhabited and uninhabited sediments; shrimp-inhabited sediment contained a higher proportion of proteobacterial sequences, including in particular a twofold increase in Gammaproteobacteria. Chao1 and ACE diversity estimates showed that taxon richness within surface bacterial communities in shrimp-inhabited sediment was at least threefold higher than that in uninhabited sediment. This study shows that bioturbation can result in significant structural and compositional changes in sediment bacterial communities, increasing bacterial diversity in surface sediments and resulting in distinct bacterial communities even at depth within the burrow. In an area of high macrofaunal abundance, this could lead to alterations in the microbial transformations of important nutrients at the sediment–water interface.


Animal Behaviour | 2011

Reduced sea water pH disrupts resource assessment and decision making in the hermit crab Pagurus bernhardus

K.L. de la Haye; John I. Spicer; Steve Widdicombe; Mark Briffa

The decisions that animals make are based on information gathered from their environment, and can have consequences for their fitness and survival. Such processes can be disrupted by environmental change. Hermit crabs find and select the gastropod shells they inhabit using chemical and visual cues, and tactile assessment. The choice of an optimal shell is important since it provides shelter against environmental extremes and protection against predators; inhabiting a suboptimal shell can also reduce fecundity. Hermit crabs are subject to cyclical reductions in the pH of the water in the intertidal rock pools that they inhabit, and such reductions may be further exacerbated by climate change. Reduced sea water pH, a consequence of ocean acidification and leaks from geological storage sites, has already been shown to disrupt the behaviour of marine animals. We investigated the effects of reduced sea water pH on the shell assessment and selection behaviour of the hermit crab Pagurus bernhardus. Under highly reduced pH conditions (pH 6.8) crabs were less likely to change from a suboptimal to an optimal shell than those in untreated sea water; those that did change shells took longer to do so. Crabs in the reduced pH treatment also showed significantly lower antennular flicking rates (the ‘sniffing’ response in decapods) and reduced movement. Thus, a reduction in sea water pH disrupts the resource assessment and decision-making processes of these crabs, indicating that the ability to acquire a vital resource may be influenced by both naturally occurring environmental cycles and anthropogenically induced environmental change.


Environmental Science & Technology | 2014

1H NMR Metabolomics Reveals Contrasting Response by Male and Female Mussels Exposed to Reduced Seawater pH, Increased Temperature, and a Pathogen

Rob Ellis; John I. Spicer; Jonathan J. Byrne; Ulf Sommer; Mark R. Viant; Daniel White; Steve Widdicombe

Human activities are fundamentally altering the chemistry of the worlds oceans. Ocean acidification (OA) is occurring against a background of warming and an increasing occurrence of disease outbreaks, posing a significant threat to marine organisms, communities, and ecosystems. In the current study, (1)H NMR spectroscopy was used to investigate the response of the blue mussel, Mytilus edulis, to a 90-day exposure to reduced seawater pH and increased temperature, followed by a subsequent pathogenic challenge. Analysis of the metabolome revealed significant differences between male and female organisms. Furthermore, males and females are shown to respond differently to environmental stress. While males were significantly affected by reduced seawater pH, increased temperature, and a bacterial challenge, it was only a reduction in seawater pH that impacted females. Despite impacting males and females differently, stressors seem to act via a generalized stress response impacting both energy metabolism and osmotic balance in both sexes. This study therefore has important implications for the interpretation of metabolomic data in mussels, as well as the impact of environmental stress in marine invertebrates in general.


Polar Biology | 2011

Ocean warming and acidification; implications for the Arctic brittlestar Ophiocten sericeum

Hannah L. Wood; John I. Spicer; M. A. Kendall; D. M. Lowe; Steve Widdicombe

The Arctic Ocean currently has the highest global average pH. However, due to increasing atmospheric CO2 levels, it will become a region with one of the lowest global pH levels. In addition, Arctic waters will also increase in temperature as a result of global warming. These environmental changes can pose a significant threat for marine species, and in particular true Arctic species that are adapted to the historically cold and relatively stable abiotic conditions of the region. Consequently, we investigated some key physiological responses of brittlestar Ophiocten sericeum, a polar endemic which can dominate benthic infauna, to a temperature increase of 3.5°C (ambient, 5–8.5°C) and CO2 induced reduction in pH of 0.6 units (pH 7.7) and 1 unit (pH 7.3) below ambient (pH 8.3). Metabolism was upregulated at low pH. Faster arm regeneration stimulated by increased temperature was counteracted by low pH; at pH 7.3 in the high-temperature treatment, the maintenance of calcium carbonate structures in undersaturated conditions resulted in reduction in the rate of arm regeneration, possibly due to accelerated the use of energy reserves. If so, this could result in an energy deficit at times of increased energetic costs associated with responding to the combined factors of high temperature and low pH.


Philosophical Transactions of the Royal Society B | 2013

Bioturbation determines the response of benthic ammonia-oxidizing microorganisms to ocean acidification

Bonnie Laverock; Vassilis Kitidis; Karen Tait; Jack A. Gilbert; A.M. Osborn; Steve Widdicombe

Ocean acidification (OA), caused by the dissolution of increasing concentrations of atmospheric carbon dioxide (CO2) in seawater, is projected to cause significant changes to marine ecology and biogeochemistry. Potential impacts on the microbially driven cycling of nitrogen are of particular concern. Specifically, under seawater pH levels approximating future OA scenarios, rates of ammonia oxidation (the rate-limiting first step of the nitrification pathway) have been shown to dramatically decrease in seawater, but not in underlying sediments. However, no prior study has considered the interactive effects of microbial ammonia oxidation and macrofaunal bioturbation activity, which can enhance nitrogen transformation rates. Using experimental mesocosms, we investigated the responses to OA of ammonia oxidizing microorganisms inhabiting surface sediments and sediments within burrow walls of the mud shrimp Upogebia deltaura. Seawater was acidified to one of four target pH values (pHT 7.90, 7.70, 7.35 and 6.80) in comparison with a control (pHT 8.10). At pHT 8.10, ammonia oxidation rates in burrow wall sediments were, on average, fivefold greater than in surface sediments. However, at all acidified pH values (pH ≤ 7.90), ammonia oxidation rates in burrow sediments were significantly inhibited (by 79–97%; p < 0.01), whereas rates in surface sediments were unaffected. Both bacterial and archaeal abundances increased significantly as pHT declined; by contrast, relative abundances of bacterial and archaeal ammonia oxidation (amoA) genes did not vary. This research suggests that OA could cause substantial reductions in total benthic ammonia oxidation rates in coastal bioturbated sediments, leading to corresponding changes in coupled nitrogen cycling between the benthic and pelagic realms.


Nature Ecology and Evolution | 2017

Species-specific responses to ocean acidification should account for local adaptation and adaptive plasticity

Cristian A. Vargas; Nelson A. Lagos; Marco A. Lardies; Cristian Duarte; Patricio H. Manríquez; Victor M. Aguilera; Bernardo R. Broitman; Steve Widdicombe; Sam Dupont

Global stressors, such as ocean acidification, constitute a rapidly emerging and significant problem for marine organisms, ecosystem functioning and services. The coastal ecosystems of the Humboldt Current System (HCS) off Chile harbour a broad physical–chemical latitudinal and temporal gradient with considerable patchiness in local oceanographic conditions. This heterogeneity may, in turn, modulate the specific tolerances of organisms to climate stress in species with populations distributed along this environmental gradient. Negative response ratios are observed in species models (mussels, gastropods and planktonic copepods) exposed to changes in the partial pressure of CO2 (pCO2) far from the average and extreme pCO2 levels experienced in their native habitats. This variability in response between populations reveals the potential role of local adaptation and/or adaptive phenotypic plasticity in increasing resilience of species to environmental change. The growing use of standard ocean acidification scenarios and treatment levels in experimental protocols brings with it a danger that inter-population differences are confounded by the varying environmental conditions naturally experienced by different populations. Here, we propose the use of a simple index taking into account the natural pCO2 variability, for a better interpretation of the potential consequences of ocean acidification on species inhabiting variable coastal ecosystems. Using scenarios that take into account the natural variability will allow understanding of the limits to plasticity across organismal traits, populations and species.

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John I. Spicer

Plymouth State University

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Karen Tait

Plymouth Marine Laboratory

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Jerry Blackford

Plymouth Marine Laboratory

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Bonnie Laverock

Plymouth Marine Laboratory

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M. A. Kendall

Plymouth Marine Laboratory

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Piero Calosi

Université du Québec à Rimouski

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Hannah L. Wood

University of Gothenburg

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Baixin Chen

Heriot-Watt University

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Ana M. Queirós

Plymouth Marine Laboratory

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