Browsing by Author "Stubbington, Rachel"

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    Disentangling responses to natural stressor and human impact gradients in river ecosystems across Europe
    (Wiley, 2021-11-01) Stubbington, Rachel; Sarremejane, Romain; Laini, Alex; Cid, Núria; Csabai, Zoltán; England, Judy; Munné, Antoni; Aspin, Thomas; Bonada, Núria; Bruno, Daniel; Cauvy-Fraunie, Sophie; Chadd, Richard; Dienstl, Claudia; Fortuño Estrada, Pau; Graf, Wolfram; Gutiérrez-Cánovas, Cayetano; House, Andy; Karaouzas, Ioannis; Kazila, Eleana; Millán, Andrés; Morais, Manuela; Pařil, Petr; Pickwell, Alex; Polášek, Marek; Sánchez-Fernández, David; Tziortzis, Iakovos; Várbíró, Gábor; Voreadou, Catherina; Walker-Holden, Emma; White, James C.; Datry, Thibault
    1. Rivers are dynamic ecosystems in which both human impacts and climate-driven drying events are increasingly common. These anthropogenic and natural stressors interact to influence the biodiversity and functioning of river ecosystems. Disentangling ecological responses to these interacting stressors is necessary to guide management actions that support ecosystems adapting to global change. 2. We analysed the independent and interactive effects of human impacts and natural drying on aquatic invertebrate communities—a key biotic group used to assess the health of European freshwaters. We calculated biological response metrics representing communities from 406 rivers in eight European countries: taxonomic richness, functional richness and redundancy, and biomonitoring indices that indicate ecological status. We analysed metrics based on the whole community and on a group of taxa with traits promoting resistance and/or resilience (‘high RR’) to drying. We also examined how responses vary across Europe in relation to climatic aridity. 3. Most community metrics decreased independently in response to impacts and drying. A richness-independent biomonitoring index (the average score per taxon; ASPT) showed particular potential for use in biomonitoring, and should be considered alongside new metrics representing high RR diversity, to promote accurate assessment of ecological status. 4. High RR taxonomic richness responded only to impacts, not drying. However, these predictors explained little variance in richness and other high RR metrics, potentially due to low taxonomic richness. Metric responsiveness could thus be enhanced by developing region-specific high RR groups comprising sufficient taxa with sufficiently variable impact sensitivities to indicate ecological status. 5. Synthesis and applications. Metrics are needed to assess the ecological status of dynamic river ecosystems—including those that sometimes dry—and thus to identify priority sites requiring action to tackle the causes of environmental degradation. Our results inform recommendations guiding the development of such metrics. We propose concurrent use of richness-independent ‘average score per taxon’ indices and metrics that characterize the richness of resistant and resilient taxa. We observed interactions between aridity, impacts and drying, highlighting that these new metrics should be region specific, river type specific and adaptable, promoting their ability to inform management actions that protect biodiversity in river ecosystems responding to climate change.
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    Human impacts mediate freshwater invertebrate community responses to and recovery from drought
    (Wiley, 2024-11) Sarremejane, Romain; England, Judy; Dunbar, Mike; Brown, Rosalind; Naura, Marc; Stubbington, Rachel
    Drought is an increasing risk to the biodiversity within rivers—ecosystems which are already impacted by human activities. However, the long‐term spatially replicated studies needed to generate understanding of how anthropogenic stressors alter ecological responses to drought are lacking. We studied aquatic invertebrate communities in 2500 samples collected from 179 sites on rivers emerging from England's chalk aquifer over three decades. We tested two sets of alternative hypotheses describing responses to and recovery from drought in interaction with human impacts affecting water quality, fine sediment, water temperature, channel morphology, flow and temporal change in land use. We summarized communities using taxa richness, an index indicating tolerance of anthropogenic degradation (average score per taxon, ASPT) and deviation from the average composition. Responses to drought were altered by interactions with human impacts. Poor water quality exacerbated drought‐driven reductions in taxa richness. Drought‐driven deviations from the average community composition were reduced and enhanced at sites impacted by flow augmentation (e.g. effluent releases) and flow reduction (e.g. abstraction), respectively. Human impacts altered post‐drought recovery. Increases in richness were lower at sites impacted by water abstraction and higher at sites with augmented flows, in particular as recovery trajectories extended beyond 3 years. ASPT recovered faster at sites that gained woodland compared to urban land, due to their greater recovery potential, that is, their lower drought‐driven minimum values and higher post‐drought maximum values. Synthesis and applications. We show that communities in river ecosystems exposed to human impacts—in particular poor water quality, altered flow volumes and land use change—are particularly vulnerable to drought. These results provide evidence that management actions taken to enhance water quality, regulate abstraction and restore riparian land use could promote ecological resilience to drought in groundwater‐dominated rivers such as globally rare chalk streams and other rivers of the Anthropocene, as they adapt to a future characterized by increasing climatic extremity.
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    The riverine bioreactor: an integrative perspective on biological decomposition of organic matter across riverine habitats
    (Elsevier, 2021-02-01) Peralta-Maraver, Ignacio; Stubbington, Rachel; Arnon, Shai; Kratina, Pavel; Krause, Stefan; Mello Cionek, Vivian de; Leite, Nei Kavaguichi; Lemes da Silva, Aurea Luiza; Thomazi, Sidinei Magela; Posselt, Malte; Milner, Victoria Susan; Momblanch, Andrea; Moretti, Marcelo S.; Nóbrega, Rodolfo L. B.; Perkins, Daniel M.; Petrucio, Mauricio M.; Reche, Isabel; Saito, Victor; Sarmento, Hugo; Strange, Emily; Taniwaki, Ricardo Hideo; White, James C.; Alves, Gustavo Henrique Zaia; Robertson, Anne L.
    Riverine ecosystems can be conceptualized as ‘bioreactors’ (the riverine bioreactor) which retain and decompose a wide range of organic substrates. The metabolic performance of the riverine bioreactor is linked to their community structure, the efficiency of energy transfer along food chains, and complex interactions among biotic and abiotic environmental factors. However, our understanding of the mechanistic functioning and capacity of the riverine bioreactor remains limited. We review the state of knowledge and outline major gaps in the understanding of biotic drivers of organic matter decomposition processes that occur in riverine ecosystems, across habitats, temporal dimensions, and latitudes influenced by climate change. We propose a novel, integrative analytical perspective to assess and predict decomposition processes in riverine ecosystems. We then use this model to analyse data to demonstrate that the size-spectra of a community can be used to predict decomposition rates by analysing an illustrative dataset. This modelling methodology allows comparison of the riverine bioreactor’s performance across habitats and at a global scale. Our integrative analytical approach can be applied to advance understanding of the functioning and efficiency of the riverine bioreactor as hotspots of metabolic activity. Application of insights gained from such analyses could inform the development of strategies that promote the functioning of the riverine bioreactor across global ecosystems