ImportanceCurrent treatments manage symptoms of Parkinson disease (PD), but no known treatment sl... more ImportanceCurrent treatments manage symptoms of Parkinson disease (PD), but no known treatment slows disease progression. Preclinical and epidemiological studies support the potential use of statins as disease-modifying therapy.ObjectiveTo determine whether simvastatin has potential as a disease-modifying treatment for patients with moderate PD.Design, Setting, and ParticipantsThis randomized clinical trial, a double-blind, parallel-group, placebo-controlled futility trial, was conducted between March 2016 and May 2020 within 23 National Health Service Trusts in England. Participants aged 40 to 90 years with a diagnosis of idiopathic PD, with a modified Hoehn and Yahr stage of 3.0 or less while taking medication, and taking dopaminergic medication with wearing-off phenomenon were included. Data were analyzed from May 2020 to September 2020, with additional analysis in February 2021.InterventionsParticipants were allocated 1:1 to simvastatin or matched placebo via a computer-generate...
Biological invasions constitute a pervasive and growing threat to the biodiversity and functionin... more Biological invasions constitute a pervasive and growing threat to the biodiversity and functioning of freshwater ecosystems. Macrophytes are key primary producers and ecosystem engineers in freshwaters, meaning that alien macrophyte invasions have the capacity to alter the structure and function of recipient aquatic ecosystems profoundly. Although prevailing wisdom holds that alien macrophyte invasions tend to compromise freshwater ecosystem structure and function, the ecological impacts of alien macrophyte invasion have not been quantitatively reviewed to date. Here we present a global meta‐analysis of 202 cases from 53 research articles, exploring the impacts of alien macrophyte invasion on the abundance and diversity of three ubiquitous and ecologically important focal groups, which together comprise the bulk of non‐microbial freshwater biodiversity: resident macrophytes, macroinvertebrates and fish. Our synthesis includes data from all continents except Antarctica and Asia, covering 25 alien macrophyte species, but reveals considerable taxonomic and geographical biases in knowledge. Meta‐analysis results reveal that invasion by alien macrophytes has an overall negative impact on taxonomic diversity of the three focal groups, but no consistent effect on abundance. At a finer resolution, we detect a strong negative effect of alien macrophyte invasion on resident macrophyte abundance and diversity, and a significant but smaller positive effect of submerged alien macrophyte invasion on macroinvertebrates. Effects on fish appear inconsistent. Our findings emphasise the importance of context‐ and taxon‐specific ecological research in informing appropriate and proportionate management of alien macrophyte invasions, since alien macrophyte impacts are not consistently negative. We also identify significant geographical and taxonomic limitations in existing studies, quantitative data being lacking for many alien taxa.
1. Nestedness is a composite property of many suites of biotas. Such patterns may be driven by di... more 1. Nestedness is a composite property of many suites of biotas. Such patterns may be driven by dispersal limitation, species-area relationships, hierarchical niche requirements, or occur as an artefact of passive sampling. Despite its widespread occurrence, few studies have explored the factors underlying nested subset structure, and ecological distinctions between nested and non-nested (idiosyncratic) taxa within a region have been largely ignored. 2. Macroinvertebrate assemblages from 45 heathland ponds in southwest England are used to (i) unravel the relative importance of processes driving nested subset structure and (ii) test spatially explicit hypotheses concerning the response of nested and idiosyncratic taxa to parameters shown to structure assemblage-level nestedness. 3. Despite being dominated by taxa with good powers of inter-site dispersal, pond macroinvertebrate assemblages were found to be significantly nested. This nesting was not due to passive sampling, and was best explained by pond area, with habitat parameters and isolation being of secondary importance. 4. The spatial responses of nested and idiosyncratic taxa matched predictions; nested taxa showed strong spatial structure, which was reduced when the effects of pond area and habitat were removed. In contrast, a greater proportion of idiosyncratic taxa were completely spatially random and exhibited weaker responses to factors that structure assemblage level nestedness. 5. Nested and idiosyncratic species tend to differ ecologically: idiosyncratic taxa generally possess broad ecological tolerance and good dispersal capacity, whilst nested species are more likely to have narrow tolerances or limited powers of dispersal. 6. Factors structuring nestedness in ponds can be viewed as probabilistic filters which act to limit the spatial distribution of species with narrow ecological tolerance or low dispersal tendency. Nestedness analysis alone fails to elucidate processes that structure assemblage composition. The additional use of spatially explicit analyses is important if processes that generate nested pattern across a region are to be understood.
Ash dieback is a chronic condition affecting a high percentage of mature pre‐senescent individual... more Ash dieback is a chronic condition affecting a high percentage of mature pre‐senescent individuals of Fraxinus excelsior L. growing in hedgerows in mainland Britain. The ash bud moth has been mooted as a possible causal agent of dieback through attacking terminal buds of twigs and curbing tree growth: dieback is characterised by failure of terminal buds to flush. Patterns of winter bud utilisation by larvae of the ash bud moth Prays fraxinella were determined by examination of samples gathered during a field survey in 1989. Further twigs gathered in 1993 were used to determine mean values for various characteristics of buds which might influence bud choice by larvae. These bud characteristics were used to generate expected patterns of larval utilisation of buds at different positions on the twig; observed and expected distributions were compared by G‐tests. P. fraxinella larvae display a complex preference for buds situated at different points on the twigs, with preference for buds being strongly affected by bud size, and with preference for buds in the middle of the twigs being higher than that for either apical or basal buds possibly due to interactions between bud size, scales thicknesses, and availability of food within the buds. These findings suggest that failure of terminal buds to flush in instances of ash dieback are not likely to be due to bud moth attack. Size based preference for buds may have deleterious consequences for young trees, however, in which lateral buds are often too small to provide adequate resources for P. fraxinella larvae.
Damage to the buds of the common ash (Fraxinus excelsior L.) by larvae of the ash bud moth Prays ... more Damage to the buds of the common ash (Fraxinus excelsior L.) by larvae of the ash bud moth Prays fraxinella Bjerk. was investigated in trees growing in the presence, or absence, of an adjacent ditch. The presence of a ditch was correlated with increased damage levels due to bud moth. Saplings were used in an experiment to compare the effects of artificial drought and root damage with those of ditches. Both root damage and drought elicited analogous responses to those observed in trees growing near a ditch, being associated with ele, vated levels of bud moth exploitation and reduced growth of shoots. There exists a documented link between ditches, root disturbance, and the dieback of hedgerow ash trees in Great Britain; the response of P. fraxinella to environmental disturbances associated with dieback is hypothesised to be evidence of the possible role Of moth damage as a causal factor in dieback.
Summary1. Cross‐species macroecological comparisons in freshwater invertebrates have been restric... more Summary1. Cross‐species macroecological comparisons in freshwater invertebrates have been restricted by a lack of large‐scale distributional data, and robust phylogenies. Here, we use data from the OdonataCentral database to explore body length–range size and wing length–range size relationships in damselflies from the genus Enallagma; the recent publication of a phylogeny for this group meant that, as well as a cross‐species analysis, we were able to assess relationships in a phylogenetically controlled manner.2. For cross‐species comparisons, only wing length showed significant (positive) regression relationships with range size and occupancy, although the inclusion of body length in multiple regressions increased the fit of the models. Damselflies with larger wings relative to their body length had larger distributions, a result confirmed by a significant positive relationship between range size and residuals from the regression of wing size on body size.3. For the phylogenetically controlled analyses, only wing length contrast scores were significantly related to distribution patterns and entered into regression models; the significant positive relationships between wing length contrasts and both range size and occupancy contrasts suggested that evolutionary increases in wing length had occurred alongside range expansions.4. Together these results suggest that species of Enallagma with larger wings (both absolute and relative to body length) tend to be more widely distributed in North America and that the evolution of wing size may have played a role in range expansion. No such relationships were evident for body size. We discuss the potential importance of wing morphometrics for studying the evolutionary ecology of freshwater insects.
The pattern of terminal bud and shoot attack of 100 common ash saplings by the ash bud moth Prays... more The pattern of terminal bud and shoot attack of 100 common ash saplings by the ash bud moth Prays jiminella was studied over a winter season. Buds and shoots were heavily attacked by the moth, overall 25% were damaged by the moth at some stage, and of these 71% were killed either directly or indirectly as a result of attack. The majority of attacks were mined buds, and this form of attack resulted in the highest subsequent bud death. Mined shoots were less common, and also had less deleterious consequences. Leader buds and shoots were more likely to be attacked, and to die, than those lower down the trees; terminal buds at the bottom of the trees were significantly less heavily attacked than those at the leader. Shoot elongation within a tree was correlated with the proportion of its terminal buds attacked by the moth, and more significantly with the proportion of the tree's buds surviving attacks. The mean shoot elongation from buds surviving moth attack was greater than that of unattacked buds, and whilst it is possible that damage has a short-term stimulatory effect upon growth, effects of bud size and height within the tree may also explain this trend. P. fraxinelfu attack has been shown to retard the growth of ash, and also to cause growth deformities as a result of the death of attacked terminal buds. It is concluded that the extent and consequences of P. fiaxinella attack have serious consequences for the silviculture of ash, and that more research is required into possible control of the moth in future silviculture of the species.
<p>Note:</p><p>* indicates that the random nested season effect is analysed as ... more <p>Note:</p><p>* indicates that the random nested season effect is analysed as a fixed effect in the simplified model. In both models all factor * covariate interactions were non-significant.</p><p>Type I SS PERMANCOVA+ results for epibiota assemblage data from 2007–2010; n = 564 for the <i>Sargassum</i> treatment and n = 571 for the Control treatment over 4 years with 3 seasons per year. <i>P</i><sub><i>disp</i></sub> gives <i>P</i> values for homogeneity of dispersion (PERMDISP) tests for main effects, <i>P</i><sub><i>simp</i></sub> gives the <i>P</i> values for a simplified model excluding the non-significant effect of Year and its interactions with other main effects.</p
pinnatifida and Sargassum muticum in the United Kingdom. We conducted choice and no choice experi... more pinnatifida and Sargassum muticum in the United Kingdom. We conducted choice and no choice experiments to determine herbivore preference on these invaders relative to six functionally-similar native species. We also measured and compared species traits associated with defence against herbivory (carbon to nitrogen ratio, polyphenolic concentration, tensile strength, and compensatory growth). There were no differences in the biomass consumed between invasive and native species for either choice or no choice tests. The carbon to nitrogen ratio (a measure of nutritional quality) was significantly lower for S. muticum compared to the three native fucoid species, but measures of the other three defence traits were similar or even greater for invasive species compared with native species. Taken together, it is unlikely that Abstract Invasive species are a global threat to biodiversity and there is a pressing need to better understand why some species become invasive outside of their native range, and others do not. One explanation for invasive species success is their release from concurrent natural enemies upon introduction to the nonnative range. The so-called enemy release hypothesis (ERH) has conflicting support, depending upon the ecosystem and species investigated. To date, most studies testing the generality of the ERH have focused on terrestrial ecosystems. Here, we tested whether enemy release might contribute to the success of the invasive non-native brown seaweeds Undaria
Journal of Experimental Marine Biology and Ecology, 2021
Handling the heat: Responses of two congeneric limpet species to environmental temperature differ... more Handling the heat: Responses of two congeneric limpet species to environmental temperature differences Redfern, JC
File contains data on biomass accumulation and loss, grazer abundance (Patella pellucida and Gibb... more File contains data on biomass accumulation and loss, grazer abundance (Patella pellucida and Gibbula cineraria), degradation rates and detritivore abundance in the mesh bags
While research on ocean acidification (OA) impacts on coral reefs has focused on calcification, r... more While research on ocean acidification (OA) impacts on coral reefs has focused on calcification, relatively little is known about effects on coral photosynthesis and respiration, despite these being among the most plastic metabolic processes corals may use to acclimatize to adverse conditions. Here, we present data collected between 2016 and 2018 at three natural CO<sub>2</sub> seeps in Papua New Guinea where we measured the metabolic flexibility (i.e. <i>in hospite</i> photosynthesis and dark respiration) of 12 coral species. Despite some species-specific variability, metabolic rates as measured by net oxygen flux tended to be higher at high <i>p</i>CO<sub>2</sub> (<i>ca</i> 1200 µatm), with increases in photosynthesis exceeding those of respiration, suggesting greater productivity of <i>Symbiodiniacea</i> photosynthesis <i>in hospite</i>, and indicating the potential for metabolic flexibility that may enable these species to thrive in environments with high <i>p</i>CO<sub>2</sub>. However, laboratory and field observations of coral mortality under high CO<sub>2</sub> conditions associated with coral bleaching suggests that this metabolic subsidy does not result in coral higher resistance to extreme thermal stress. Therefore, the combined effects of OA and global warming may lead to a strong decrease in coral diversity despite the stimulating effect on coral productivity of OA alone.
Fish exhibit impaired sensory function and altered behaviour at levels of ocean acidification exp... more Fish exhibit impaired sensory function and altered behaviour at levels of ocean acidification expected to occur owing to anthropogenic carbon dioxide emissions during this century. We provide the first evidence of the effects of ocean acidification on reproductive behaviour of fish in the wild. Satellite and sneaker male ocellated wrasse (Symphodus ocellatus) compete to fertilize eggs guarded by dominant nesting males. Key mating behaviours such as dominant male courtship and nest defence did not differ between sites with ambient versus elevated CO2 concentrations. Dominant males did, however, experience significantly lower rates of pair spawning at elevated CO2 levels. Despite the higher risk of sperm competition found at elevated CO2, we also found a trend of lower satellite and sneaker male paternity at elevated CO2. Given the importance of fish for food security and ecosystem stability, this study highlights the need for targeted research into the effects of rising CO2 levels on patterns of reproduction in wild fish
Publisher's PDF, also known as Final Published Version Link to published version (if availab... more Publisher's PDF, also known as Final Published Version Link to published version (if available):
1. Climate change is driving a redistribution of species and reconfiguration of ecological commun... more 1. Climate change is driving a redistribution of species and reconfiguration of ecological communities at a global scale. Persistent warming in many regions has caused species to extend their geographical ranges into new habitats, with thermally-tolerant species often becoming competitively dominant over species with colder affinities. Although these climatedriven changes in species abundance and diversity are well documented, their ecosystemlevel implications are poorly understood, and resolving whether reconfigured communities can maintain fundamental ecosystem functions represents a pressing challenge in an increasingly warmer world. 2. Here, we investigated how climate-driven substitutions of foundation species influence processes associated with carbon and nutrient cycling (biomass production, detritus flow, herbivory, decomposition) by comparing two habitat-forming kelp species with contrasting thermal affinities. We examined the wider ecosystem consequences of such shifts for the observed (and predicted) emergence of novel marine forest communities in the NE Atlantic, which are expected to become more dominated by range-expanding, warm-temperate kelp species. 3. Warm-temperate kelps both accumulated and released 80% more biomass than the coldtemperate species despite being taxonomically closely-related and morphologically similar. Furthermore, the warm-temperate species accumulated biomass and released detritus yearround, whereas the cold-temperate species did so during short, discrete periods. The warmtemperate kelps supported higher densities of invertebrate grazers and were a preferred food source. Finally, their detritus decomposed 6.5 times faster, despite supporting comparable numbers of detritivores. Overall, our results indicate an important shift in the cycling of organic matter along large sections of NE Atlantic coastline following the climatedriven expansion of a warm-affinity kelp, with novel forests supplying large amounts of temporally-continuous-yet highly labile-organic matter. 4 4. Synthesis. Collectively, our results show that, like species invasions, climate-driven range expansions and consequent shifts in the identity of dominant species can modify a wide range of important ecosystem processes. However, alterations in overall ecosystem functioning may be relatively limited where foundation species share similar ecological and functional traits.
ImportanceCurrent treatments manage symptoms of Parkinson disease (PD), but no known treatment sl... more ImportanceCurrent treatments manage symptoms of Parkinson disease (PD), but no known treatment slows disease progression. Preclinical and epidemiological studies support the potential use of statins as disease-modifying therapy.ObjectiveTo determine whether simvastatin has potential as a disease-modifying treatment for patients with moderate PD.Design, Setting, and ParticipantsThis randomized clinical trial, a double-blind, parallel-group, placebo-controlled futility trial, was conducted between March 2016 and May 2020 within 23 National Health Service Trusts in England. Participants aged 40 to 90 years with a diagnosis of idiopathic PD, with a modified Hoehn and Yahr stage of 3.0 or less while taking medication, and taking dopaminergic medication with wearing-off phenomenon were included. Data were analyzed from May 2020 to September 2020, with additional analysis in February 2021.InterventionsParticipants were allocated 1:1 to simvastatin or matched placebo via a computer-generate...
Biological invasions constitute a pervasive and growing threat to the biodiversity and functionin... more Biological invasions constitute a pervasive and growing threat to the biodiversity and functioning of freshwater ecosystems. Macrophytes are key primary producers and ecosystem engineers in freshwaters, meaning that alien macrophyte invasions have the capacity to alter the structure and function of recipient aquatic ecosystems profoundly. Although prevailing wisdom holds that alien macrophyte invasions tend to compromise freshwater ecosystem structure and function, the ecological impacts of alien macrophyte invasion have not been quantitatively reviewed to date. Here we present a global meta‐analysis of 202 cases from 53 research articles, exploring the impacts of alien macrophyte invasion on the abundance and diversity of three ubiquitous and ecologically important focal groups, which together comprise the bulk of non‐microbial freshwater biodiversity: resident macrophytes, macroinvertebrates and fish. Our synthesis includes data from all continents except Antarctica and Asia, covering 25 alien macrophyte species, but reveals considerable taxonomic and geographical biases in knowledge. Meta‐analysis results reveal that invasion by alien macrophytes has an overall negative impact on taxonomic diversity of the three focal groups, but no consistent effect on abundance. At a finer resolution, we detect a strong negative effect of alien macrophyte invasion on resident macrophyte abundance and diversity, and a significant but smaller positive effect of submerged alien macrophyte invasion on macroinvertebrates. Effects on fish appear inconsistent. Our findings emphasise the importance of context‐ and taxon‐specific ecological research in informing appropriate and proportionate management of alien macrophyte invasions, since alien macrophyte impacts are not consistently negative. We also identify significant geographical and taxonomic limitations in existing studies, quantitative data being lacking for many alien taxa.
1. Nestedness is a composite property of many suites of biotas. Such patterns may be driven by di... more 1. Nestedness is a composite property of many suites of biotas. Such patterns may be driven by dispersal limitation, species-area relationships, hierarchical niche requirements, or occur as an artefact of passive sampling. Despite its widespread occurrence, few studies have explored the factors underlying nested subset structure, and ecological distinctions between nested and non-nested (idiosyncratic) taxa within a region have been largely ignored. 2. Macroinvertebrate assemblages from 45 heathland ponds in southwest England are used to (i) unravel the relative importance of processes driving nested subset structure and (ii) test spatially explicit hypotheses concerning the response of nested and idiosyncratic taxa to parameters shown to structure assemblage-level nestedness. 3. Despite being dominated by taxa with good powers of inter-site dispersal, pond macroinvertebrate assemblages were found to be significantly nested. This nesting was not due to passive sampling, and was best explained by pond area, with habitat parameters and isolation being of secondary importance. 4. The spatial responses of nested and idiosyncratic taxa matched predictions; nested taxa showed strong spatial structure, which was reduced when the effects of pond area and habitat were removed. In contrast, a greater proportion of idiosyncratic taxa were completely spatially random and exhibited weaker responses to factors that structure assemblage level nestedness. 5. Nested and idiosyncratic species tend to differ ecologically: idiosyncratic taxa generally possess broad ecological tolerance and good dispersal capacity, whilst nested species are more likely to have narrow tolerances or limited powers of dispersal. 6. Factors structuring nestedness in ponds can be viewed as probabilistic filters which act to limit the spatial distribution of species with narrow ecological tolerance or low dispersal tendency. Nestedness analysis alone fails to elucidate processes that structure assemblage composition. The additional use of spatially explicit analyses is important if processes that generate nested pattern across a region are to be understood.
Ash dieback is a chronic condition affecting a high percentage of mature pre‐senescent individual... more Ash dieback is a chronic condition affecting a high percentage of mature pre‐senescent individuals of Fraxinus excelsior L. growing in hedgerows in mainland Britain. The ash bud moth has been mooted as a possible causal agent of dieback through attacking terminal buds of twigs and curbing tree growth: dieback is characterised by failure of terminal buds to flush. Patterns of winter bud utilisation by larvae of the ash bud moth Prays fraxinella were determined by examination of samples gathered during a field survey in 1989. Further twigs gathered in 1993 were used to determine mean values for various characteristics of buds which might influence bud choice by larvae. These bud characteristics were used to generate expected patterns of larval utilisation of buds at different positions on the twig; observed and expected distributions were compared by G‐tests. P. fraxinella larvae display a complex preference for buds situated at different points on the twigs, with preference for buds being strongly affected by bud size, and with preference for buds in the middle of the twigs being higher than that for either apical or basal buds possibly due to interactions between bud size, scales thicknesses, and availability of food within the buds. These findings suggest that failure of terminal buds to flush in instances of ash dieback are not likely to be due to bud moth attack. Size based preference for buds may have deleterious consequences for young trees, however, in which lateral buds are often too small to provide adequate resources for P. fraxinella larvae.
Damage to the buds of the common ash (Fraxinus excelsior L.) by larvae of the ash bud moth Prays ... more Damage to the buds of the common ash (Fraxinus excelsior L.) by larvae of the ash bud moth Prays fraxinella Bjerk. was investigated in trees growing in the presence, or absence, of an adjacent ditch. The presence of a ditch was correlated with increased damage levels due to bud moth. Saplings were used in an experiment to compare the effects of artificial drought and root damage with those of ditches. Both root damage and drought elicited analogous responses to those observed in trees growing near a ditch, being associated with ele, vated levels of bud moth exploitation and reduced growth of shoots. There exists a documented link between ditches, root disturbance, and the dieback of hedgerow ash trees in Great Britain; the response of P. fraxinella to environmental disturbances associated with dieback is hypothesised to be evidence of the possible role Of moth damage as a causal factor in dieback.
Summary1. Cross‐species macroecological comparisons in freshwater invertebrates have been restric... more Summary1. Cross‐species macroecological comparisons in freshwater invertebrates have been restricted by a lack of large‐scale distributional data, and robust phylogenies. Here, we use data from the OdonataCentral database to explore body length–range size and wing length–range size relationships in damselflies from the genus Enallagma; the recent publication of a phylogeny for this group meant that, as well as a cross‐species analysis, we were able to assess relationships in a phylogenetically controlled manner.2. For cross‐species comparisons, only wing length showed significant (positive) regression relationships with range size and occupancy, although the inclusion of body length in multiple regressions increased the fit of the models. Damselflies with larger wings relative to their body length had larger distributions, a result confirmed by a significant positive relationship between range size and residuals from the regression of wing size on body size.3. For the phylogenetically controlled analyses, only wing length contrast scores were significantly related to distribution patterns and entered into regression models; the significant positive relationships between wing length contrasts and both range size and occupancy contrasts suggested that evolutionary increases in wing length had occurred alongside range expansions.4. Together these results suggest that species of Enallagma with larger wings (both absolute and relative to body length) tend to be more widely distributed in North America and that the evolution of wing size may have played a role in range expansion. No such relationships were evident for body size. We discuss the potential importance of wing morphometrics for studying the evolutionary ecology of freshwater insects.
The pattern of terminal bud and shoot attack of 100 common ash saplings by the ash bud moth Prays... more The pattern of terminal bud and shoot attack of 100 common ash saplings by the ash bud moth Prays jiminella was studied over a winter season. Buds and shoots were heavily attacked by the moth, overall 25% were damaged by the moth at some stage, and of these 71% were killed either directly or indirectly as a result of attack. The majority of attacks were mined buds, and this form of attack resulted in the highest subsequent bud death. Mined shoots were less common, and also had less deleterious consequences. Leader buds and shoots were more likely to be attacked, and to die, than those lower down the trees; terminal buds at the bottom of the trees were significantly less heavily attacked than those at the leader. Shoot elongation within a tree was correlated with the proportion of its terminal buds attacked by the moth, and more significantly with the proportion of the tree's buds surviving attacks. The mean shoot elongation from buds surviving moth attack was greater than that of unattacked buds, and whilst it is possible that damage has a short-term stimulatory effect upon growth, effects of bud size and height within the tree may also explain this trend. P. fraxinelfu attack has been shown to retard the growth of ash, and also to cause growth deformities as a result of the death of attacked terminal buds. It is concluded that the extent and consequences of P. fiaxinella attack have serious consequences for the silviculture of ash, and that more research is required into possible control of the moth in future silviculture of the species.
<p>Note:</p><p>* indicates that the random nested season effect is analysed as ... more <p>Note:</p><p>* indicates that the random nested season effect is analysed as a fixed effect in the simplified model. In both models all factor * covariate interactions were non-significant.</p><p>Type I SS PERMANCOVA+ results for epibiota assemblage data from 2007–2010; n = 564 for the <i>Sargassum</i> treatment and n = 571 for the Control treatment over 4 years with 3 seasons per year. <i>P</i><sub><i>disp</i></sub> gives <i>P</i> values for homogeneity of dispersion (PERMDISP) tests for main effects, <i>P</i><sub><i>simp</i></sub> gives the <i>P</i> values for a simplified model excluding the non-significant effect of Year and its interactions with other main effects.</p
pinnatifida and Sargassum muticum in the United Kingdom. We conducted choice and no choice experi... more pinnatifida and Sargassum muticum in the United Kingdom. We conducted choice and no choice experiments to determine herbivore preference on these invaders relative to six functionally-similar native species. We also measured and compared species traits associated with defence against herbivory (carbon to nitrogen ratio, polyphenolic concentration, tensile strength, and compensatory growth). There were no differences in the biomass consumed between invasive and native species for either choice or no choice tests. The carbon to nitrogen ratio (a measure of nutritional quality) was significantly lower for S. muticum compared to the three native fucoid species, but measures of the other three defence traits were similar or even greater for invasive species compared with native species. Taken together, it is unlikely that Abstract Invasive species are a global threat to biodiversity and there is a pressing need to better understand why some species become invasive outside of their native range, and others do not. One explanation for invasive species success is their release from concurrent natural enemies upon introduction to the nonnative range. The so-called enemy release hypothesis (ERH) has conflicting support, depending upon the ecosystem and species investigated. To date, most studies testing the generality of the ERH have focused on terrestrial ecosystems. Here, we tested whether enemy release might contribute to the success of the invasive non-native brown seaweeds Undaria
Journal of Experimental Marine Biology and Ecology, 2021
Handling the heat: Responses of two congeneric limpet species to environmental temperature differ... more Handling the heat: Responses of two congeneric limpet species to environmental temperature differences Redfern, JC
File contains data on biomass accumulation and loss, grazer abundance (Patella pellucida and Gibb... more File contains data on biomass accumulation and loss, grazer abundance (Patella pellucida and Gibbula cineraria), degradation rates and detritivore abundance in the mesh bags
While research on ocean acidification (OA) impacts on coral reefs has focused on calcification, r... more While research on ocean acidification (OA) impacts on coral reefs has focused on calcification, relatively little is known about effects on coral photosynthesis and respiration, despite these being among the most plastic metabolic processes corals may use to acclimatize to adverse conditions. Here, we present data collected between 2016 and 2018 at three natural CO<sub>2</sub> seeps in Papua New Guinea where we measured the metabolic flexibility (i.e. <i>in hospite</i> photosynthesis and dark respiration) of 12 coral species. Despite some species-specific variability, metabolic rates as measured by net oxygen flux tended to be higher at high <i>p</i>CO<sub>2</sub> (<i>ca</i> 1200 µatm), with increases in photosynthesis exceeding those of respiration, suggesting greater productivity of <i>Symbiodiniacea</i> photosynthesis <i>in hospite</i>, and indicating the potential for metabolic flexibility that may enable these species to thrive in environments with high <i>p</i>CO<sub>2</sub>. However, laboratory and field observations of coral mortality under high CO<sub>2</sub> conditions associated with coral bleaching suggests that this metabolic subsidy does not result in coral higher resistance to extreme thermal stress. Therefore, the combined effects of OA and global warming may lead to a strong decrease in coral diversity despite the stimulating effect on coral productivity of OA alone.
Fish exhibit impaired sensory function and altered behaviour at levels of ocean acidification exp... more Fish exhibit impaired sensory function and altered behaviour at levels of ocean acidification expected to occur owing to anthropogenic carbon dioxide emissions during this century. We provide the first evidence of the effects of ocean acidification on reproductive behaviour of fish in the wild. Satellite and sneaker male ocellated wrasse (Symphodus ocellatus) compete to fertilize eggs guarded by dominant nesting males. Key mating behaviours such as dominant male courtship and nest defence did not differ between sites with ambient versus elevated CO2 concentrations. Dominant males did, however, experience significantly lower rates of pair spawning at elevated CO2 levels. Despite the higher risk of sperm competition found at elevated CO2, we also found a trend of lower satellite and sneaker male paternity at elevated CO2. Given the importance of fish for food security and ecosystem stability, this study highlights the need for targeted research into the effects of rising CO2 levels on patterns of reproduction in wild fish
Publisher's PDF, also known as Final Published Version Link to published version (if availab... more Publisher's PDF, also known as Final Published Version Link to published version (if available):
1. Climate change is driving a redistribution of species and reconfiguration of ecological commun... more 1. Climate change is driving a redistribution of species and reconfiguration of ecological communities at a global scale. Persistent warming in many regions has caused species to extend their geographical ranges into new habitats, with thermally-tolerant species often becoming competitively dominant over species with colder affinities. Although these climatedriven changes in species abundance and diversity are well documented, their ecosystemlevel implications are poorly understood, and resolving whether reconfigured communities can maintain fundamental ecosystem functions represents a pressing challenge in an increasingly warmer world. 2. Here, we investigated how climate-driven substitutions of foundation species influence processes associated with carbon and nutrient cycling (biomass production, detritus flow, herbivory, decomposition) by comparing two habitat-forming kelp species with contrasting thermal affinities. We examined the wider ecosystem consequences of such shifts for the observed (and predicted) emergence of novel marine forest communities in the NE Atlantic, which are expected to become more dominated by range-expanding, warm-temperate kelp species. 3. Warm-temperate kelps both accumulated and released 80% more biomass than the coldtemperate species despite being taxonomically closely-related and morphologically similar. Furthermore, the warm-temperate species accumulated biomass and released detritus yearround, whereas the cold-temperate species did so during short, discrete periods. The warmtemperate kelps supported higher densities of invertebrate grazers and were a preferred food source. Finally, their detritus decomposed 6.5 times faster, despite supporting comparable numbers of detritivores. Overall, our results indicate an important shift in the cycling of organic matter along large sections of NE Atlantic coastline following the climatedriven expansion of a warm-affinity kelp, with novel forests supplying large amounts of temporally-continuous-yet highly labile-organic matter. 4 4. Synthesis. Collectively, our results show that, like species invasions, climate-driven range expansions and consequent shifts in the identity of dominant species can modify a wide range of important ecosystem processes. However, alterations in overall ecosystem functioning may be relatively limited where foundation species share similar ecological and functional traits.
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Papers by Andrew Foggo