5 research outputs found
Evaluating the performance of taxonomic and trait-based biomonitoring approaches for fine sediment in the UK
Fine sediment is a leading cause for the decline of aquatic biodiversity globally. There is an urgent need for
targeted monitoring to identify where management methods are required in order to reduce the delivery of fine
sediment to aquatic environments. Existing sediment-specific biomonitoring indices and indices for general
ecological health (taxonomic and trait-based) developed for use in the UK were tested in a representative set of
lowland rivers in England that consisted of a gradient of fine sediment pressures (deposited and suspended,
organic and inorganic). Index performance was modelled against environmental variables collected during
sampling and hydrological and antecedent flow variables calculated from daily flow data. Sediment-specific
indices were indicative of surface sediment deposits, whereas indices for general ecological health were more
closely associated with the organic content of fine sediment. The performance of biotic indices along fine
sediment gradients was predominantly dependent on hydrological variability. Functional diversity indices were
poorly related to different measures of fine sediment, and further development of traits-based indices and trait
databases are recommended. In summary, the results suggest that sediment-specific biomonitoring tools are
suitable for evaluating fine sediment stress in UK rivers when index scores are viewed within the context of local
hydrolog
Abiotic predictors of fine sediment accumulation in lowland rivers
The delivery of excessive fine sediment (particles
<2 mm in diameter) to rivers can cause serious deleterious effects to
aquatic ecosystems and is widely acknowledged to be one of the leading
contributors to the degradation of rivers globally. Despite advances in using
biological methods as a proxy, physical measures remain an important method
through which fine sediment can be quantified. The aim of this study was to
provide further insights into the environmental variables controlling sediment
accumulation in lowland gravel bed rivers. We sampled 21 sites, during spring
and autumn, selected to cover a gradient of excess fine sediment. Fine sediment
was sampled using a range of methods including visual assessments, the disturbance
method and suspended sediment concentrations. A range of abiotic predictors were
measured during sampling, and hydrological and antecedent flow indices were
derived from local flow gauging station data. The results show reach scale
visual estimates of fine sediment to be significantly and highly correlated
with fully quantitative estimates of total surface sediment. Multivariate
regression analysis showed that flow variables (regime, antecedent and local
flow characteristics) were strong predictors of deposited sediment metrics but
poor predictors of suspended sediment. Organic content was shown to be relatively
independent of total sediment quantity and is likely driven by other factors
which influence the supply and breakdown of organic matte
Freshwater invertebrate responses to fine sediment stress: a multi‐continent perspective
Excessive fine sediment (particles <2 mm) deposition in freshwater systems is a pervasive stressor worldwide. However, understanding of ecological response to excess fine sediment in river systems at the global scale is limited. Here, we aim to address whether there is a consistent response to increasing levels of deposited fine sediment by freshwater invertebrates across multiple geographic regions (Australia, Brazil, New Zealand and the UK). Results indicate ecological responses are not globally consistent and are instead dependent on both the region and the facet of invertebrate diversity considered, that is, taxonomic or functional trait structure. Invertebrate communities of Australia were most sensitive to deposited fine sediment, with the greatest rate of change in communities occurring when fine sediment cover was low (below 25% of the reach). Communities in the UK displayed a greater tolerance with most compositional change occurring between 30% and 60% cover. In both New Zealand and Brazil, which included the most heavily sedimented sampled streams, the communities were more tolerant or demonstrated ambiguous responses, likely due to historic environmental filtering of invertebrate communities. We conclude that ecological responses to fine sediment are not generalisable globally and are dependent on landscape filters with regional context and historic land management playing important roles.</p
Freshwater invertebrate responses to fine sediment stress: a multi‐continent perspective
Excessive fine sediment (particles <2 mm) deposition in freshwater systems is a pervasive stressor worldwide. However, understanding of ecological response to excess fine sediment in river systems at the global scale is limited. Here, we aim to address whether there is a consistent response to increasing levels of deposited fine sediment by freshwater invertebrates across multiple geographic regions (Australia, Brazil, New Zealand and the UK). Results indicate ecological responses are not globally consistent and are instead dependent on both the region and the facet of invertebrate diversity considered, that is, taxonomic or functional trait structure. Invertebrate communities of Australia were most sensitive to deposited fine sediment, with the greatest rate of change in communities occurring when fine sediment cover was low (below 25% of the reach). Communities in the UK displayed a greater tolerance with most compositional change occurring between 30% and 60% cover. In both New Zealand and Brazil, which included the most heavily sedimented sampled streams, the communities were more tolerant or demonstrated ambiguous responses, likely due to historic environmental filtering of invertebrate communities. We conclude that ecological responses to fine sediment are not generalisable globally and are dependent on landscape filters with regional context and historic land management playing important roles.</p
Supplementary information files for Freshwater invertebrate responses to fine sediment stress: a multi‐continent perspective
© the authors, CC-BY 4.0Supplemental files for article Freshwater invertebrate responses to fine sediment stress: a multi‐continent perspectiveExcessive fine sediment (particles <2 mm) deposition in freshwater systems is a pervasive stressor worldwide. However, understanding of ecological response to excess fine sediment in river systems at the global scale is limited. Here, we aim to address whether there is a consistent response to increasing levels of deposited fine sediment by freshwater invertebrates across multiple geographic regions (Australia, Brazil, New Zealand and the UK). Results indicate ecological responses are not globally consistent and are instead dependent on both the region and the facet of invertebrate diversity considered, that is, taxonomic or functional trait structure. Invertebrate communities of Australia were most sensitive to deposited fine sediment, with the greatest rate of change in communities occurring when fine sediment cover was low (below 25% of the reach). Communities in the UK displayed a greater tolerance with most compositional change occurring between 30% and 60% cover. In both New Zealand and Brazil, which included the most heavily sedimented sampled streams, the communities were more tolerant or demonstrated ambiguous responses, likely due to historic environmental filtering of invertebrate communities. We conclude that ecological responses to fine sediment are not generalisable globally and are dependent on landscape filters with regional context and historic land management playing important roles.</p