1,721,051 research outputs found
Data set supporting Thesis: Species' resilience, plasticity, and adaptation to environmental change
No full text.csv files for all raw data collected and used in the thesis Species' Resilience, Plasticity, and Adaptation to Environmental Change (2025). Data provided for all 3 data chapters: Please see accompanying ReadMe files providing information on data files for each chapter.</span
Relative importance of biodiversity and the environment in mediating ecosystem process
No full textWhilst there is a wealth of empirical studies that indicate negative ecosystem consequences of biodiversity loss, much debate remains over the existence, strength and importance of the same patterns in natural systems. We used a gradient of organic enrichment as a means of defining non-random species loss in the marine benthos and, using partial linear regression, determined the relative importance of macrofaunal biodiversity and the abiotic environment in affecting a benthic ecosystem process (bioturbation intensity; indicated by sediment mixing depth), that is important in mediating benthic functioning. Of the abiotic and biotic variables tested (n = 8), species richness and sediment total organic carbon (TOC) content together explained 65%, of the variability in this ecosystem process, with more than half of this variability explained solely by species richness. Importantly, the relative importance of biodiversity decreased at low levels of species richness and/or high levels of TOC. These results have profound implications for manipulative field experiments, where environmental factors are likely to dominate ecosystem processes, because the extent and importance of biological mediation could be underestimated. Our results also revealed that a large proportion of the explained variability in the ecosystem process is explained by the underlying reciprocal relationship (shared variability) between biodiversity and sediment TOC, highlighting the importance of species-environment interactions. If we are to fully appreciate the role of biodiversity in natural systems, Our findings suggest that the intimate relationship between species and their environment. needs to be more prominently featured in future studies that consider the ecosystem consequences of biodiversity los
Trait-mediated processes and per capita contributions to ecosystem functioning depend on conspecific density and climate conditions
No full textThe ecological consequences of environmental change are highly dependent on the functional contributions of the surviving community, but categorical descriptors commonly used to project ecosystem futures fail to capture context dependant response variability. Here, we show that intraspecific variability for a range of sediment-dwelling marine invertebrates is moderated by changes in the density of conspecifics and/or climatic conditions. Although these trait-mediated changes result in modifications to ecosystem properties, we find that the contributions of individuals to functioning are not necessarily additive but, instead, are a result of alterations to per capita performance. Our findings also indicate that trait variation within species can exert a greater influence on functioning than that of trait variation between species. Hence, projections of likely functional outcomes that scale from mean trait values are unlikely to be robust, highlighting a need to account for how and when intraspecific variability results in context-dependent community responses to change
Intraspecific variability across seasons and geographically distinct populations can modify species contributions to ecosystems
No full text1. Environmental change profoundly alters biodiversity and, by extension, species contributions to ecosystem functioning. While it is well-established that these impacts can be geographically and temporally nuanced, most assessments of species contributions to ecosystems assume that species traits are temporally and spatially fixed, and those that do acknowledge intraspecific variability have failed to fully determine its relevance to ecosystem functioning. 2. Here, using three geographically distinct populations of sediment-dwelling invertebrates, we combined a laboratory experiment with Bayesian hierarchical modelling to empirically quantify the prevalence of intraspecific trait variability in relation to geographic locality and seasonal conditions. Furthermore, we assessed the role of intraspecific trait variability in mediating sediment particle mixing, nutrient generation and benthic oxygen uptake. 3. We found that geographic and seasonal variability in body size and sediment particle reworking modified macrofaunal contributions to sediment total oxygen uptake and nutrient generation. These associations, however, were not consistent across all measured traits and ecosystem functions. 4. Our findings highlight asymmetries in both the absolute magnitude and/or direction of species responses to changing seasonal conditions, indicating that the relative functional contributions species make to ecosystems can be temporally or spatially transient and may, therefore, diverge from expectations based on contemporary functional group typologies. 5. These findings highlight a critical knowledge gap in our understanding of the key sources of variability affecting functionally important aspects of species behaviour and physiology and call for the development of dynamic ecological assessment and management approaches that account for individual, as well as species, responses to changing environments.<br/
Specific arrangements of species dominance can be more influential than evenness in maintaining ecosystem process and function
No full textThe ecological consequences of species loss are widely studied, but represent an end point of environmental forcing that is not always realised. Changes in species evenness and the rank order of dominant species are more widespread responses to directional forcing. However, despite the repercussions for ecosystem functioning such changes have received little attention. Here, we experimentally assess how the rearrangement of species dominance structure within specific levels of evenness, rather than changes in species richness and composition, affect invertebrate particle reworking and burrow ventilation behaviour - important moderators of microbial-mediated remineralisation processes in benthic environments - and associated levels of sediment nutrient release. We find that the most dominant species exert a disproportionate influence on functioning at low levels of evenness, but that changes in biomass distribution and a change in emphasis in species-environmental interactions become more important in governing system functionality as evenness increases. Our study highlights the need to consider the functional significance of alterations to community attributes, rather than to solely focus on the attainment of particular levels of diversity when safeguarding biodiversity and ecosystems that provide essential services to society
Consumer species richness and identity effects on marine macroalgal decomposition
No full textFew manipulative experiments that explicitly test the relationship between biodiversity and ecosystem function have focussed on regenerative processes such as decomposition and nutrient cycling. Of the studies that have taken place, most have concentrated on the effects of leaf litter diversity rather than the effects of consumer diversity on decomposition. In the present study, we established an in-situ mesocosm experiment on an intertidal mudflat in the Ythan Estuary, Scotland, to investigate the interactive effects of consumer diversity, resource diversity and microbial activity on algal consumption and decomposition. We assembled communities of three commonly occurring macrofaunal species (Hediste diversicolor, Hydrobia ulvae and Littorina littorea) in monoculture and all possible combinations of two and three species mixtures and supplied them with single vs two-species mixtures of the algae Fucus spiralis and Ulva intestinalis. Further, we also investigated whether algal decomposition changes nutrient remineralisation within the sediment by determining the C:N ratio of the surficial sediment. Data were analysed using extended linear regression with generalized least squares estimation to characterise the variance structure. We found that consumer species diversity effects are best explained by compositional effects and that species richness per se may not be the single most important determinant of resource use and decomposition in this community. Algal identity and invertebrate identity effects underpin the observed response and reflect species-specific traits associated with algal consumption and processing. The role of the microbial community is comparatively weak, but strongly linked to faunal activities and behaviour. The C:N ratio of the sediment increased with consumer species richness, indicating increased mineralisation in more diverse communities. Overall, our results suggest that although consumer species richness effects per se are weak, decomposition and subsequent incorporation of resources is nevertheless dependent on the composition of the decomposer community, which, in turn, has important implications for biogeochemical nutrient cycling in marine coastal habitats
Invariant Gametogenic Response of Dominant Infaunal Bivalves From the Arctic Under Ambient and Near-Future Climate Change Conditions
Full text linkArctic marine ecosystems are undergoing a series of major rapid adjustments to the regional amplification of climate change, but there is a paucity of knowledge about how changing environmental conditions might affect reproductive cycles of seafloor organisms. Shifts in species reproductive ecology may influence their entire life-cycle, and, ultimately, determine the persistence and distribution of taxa. Here, we investigate whether the combined effects of warming and ocean acidification based on near-future climate change projections affects the reproductive processes in benthic bivalves (Astarte crenata and Bathyarca glacialis) from the Barents Sea. Both species present large oocytes indicative of lecithotrophic or direct larval development after ∼4 months exposure to ambient [<2°C, ∼400 ppm (CO2)] and near-future [3–5°C, ∼550 ppm (CO2)] conditions, but we find no evidence that the combined effects of acidification and warming affect the size frequency distribution of oocytes. Whilst our observations are indicative of resilience of this reproductive stage to global changes, we also highlight that the successful progression of gametogenesis under standard laboratory conditions does not necessarily mean that successful development and recruitment will occur in the natural environment. This is because the metabolic costs of changing environmental conditions are likely to be offset by, as is common practice in laboratory experiments, feeding ad libitum. We discuss our findings in the context of changing food availability in the Arctic and conclude that, if we are to establish the vulnerability of species and ecosystems, there is a need for holistic approaches that incorporate multiple system responses to change
Macrofaunal contributions to benthic nutrient fluxes revealed by radium disequilibrium
No full textThe benthic flux of nutrients underpins marine food webs, influences conditions for life in the oceans, and contributes to climatic feedback. Estimates of these fluxes’ contributions to macro- and micronutrient cycles are, however, highly variable, generating significant uncertainty in biogeochemical models. Traditional benthic flux methodologies have potentially significant limitations, and in geochemically framed studies there is a notable omission of contributions from macrofaunal activity. 224Ra/228Th disequilibrium is a cutting-edge geochemical technique for quantifying benthic flux, however its capacity to incorporate the influence of benthic fauna has not been assessed. Here we present first results using 224Ra/228Th disequilibrium to examine the influence of four macrobenthic infaunal invertebrate species on the flux of macronutrients (NH4+, NO3-, NO2-, PO43-) between the sediment and water column. Overall, estimates from 224Ra/228Th disequilibrium were up to 15 times greater than those derived from commonly used methods, and both 224Ra and nutrient fluxes differed in the presence of different macrofauna. Greatest efflux (NH4+, PO43-) and influx (NO2-, NO3-) occurred in the presence of the burrowing actinarian Edwardsia claparedii, and 224Ra flux patterns suggested different mechanisms of influence between species. Notable variability in flux enhancement was also present between individuals of the same species, highlighting the complex relationship between biodiversity and ecosystem functioning. We conclude that 224Ra/228Th disequilibrium is a powerful tool for interdisciplinary biogeochemical and ecological studies, and if applied widely enough may more holistically represent benthic flux dynamics in the natural environment than standard approaches
Co-extinctions and co-compensatory species responses to climate change moderate ecosystem futures
No full textConsensus has been reached that the sequential loss of biodiversity leads to a non-linear and accelerating decline in ecosystem properties. The form of this relationship, however, is based on theory and empirically derived observations that do not include species co-extinctions. Here, we use data from marine benthic invertebrate communities to parameterise trait-based extinction models that adjust the probability of species extirpation and compensation by including the dependencies between different spe- cies across a gradient of climate-driven environmental change. Our simulations reveal that the inclusion of static co-extinctions leads to more pronounced declines in the trajectories of sediment bioturbation—a process of great importance to the functioning of marine ecosystems—than those observed with sequential losses of single species. Compensatory mechanisms and the allow- ance of the formation of new interactions derived from local and regional species pools moderate the compounding influence of co-extinction but introduce additional variability in community response depending on the composition and functional role of incoming and outgoing species. Our observations emphasise the importance of accounting for local and regional community dynamics, especially in highly connected systems that are prone to extinction cascades when projecting the ecosystem conse- quences of altered biodiversity
Species contributions to ecosystem process and function can be population dependent and modified by biotic and abiotic setting
No full textThere is unequivocal evidence that altered biodiversity, through changes in the expression and distribution of functional traits, can have large impacts on ecosystem properties. However, trait-based summaries of how organisms affect ecosystem properties often assume that traits show constancy within and between populations and that species contributions to ecosystem functioning are not overly affected by the presence of other species or variations in abiotic conditions. Here, we evaluate the validity of these assumptions using an experiment in which three geographically distinct populations of intertidal sediment-dwelling invertebrates are reciprocally substituted. We find that the mediation of macronutrient generation by these species can vary between different populations and show that changes in biotic and/or abiotic conditions can further modify functionally important aspects of the behaviour of individuals within a population. Our results demonstrate the importance of knowing how, when, and why traits are expressed and suggest that these dimensions of species functionality are not sufficiently well-constrained to facilitate the accurate projection of the functional consequences of change. Information regarding the ecological role of key species and assumptions about the form of species–environment interactions needs urgent refinement
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