Tracking a century of change in trophic structure and dynamics in a floodplain wetland: Integrating palaeoecological and palaeoisotopic evidence
- Kattel, Giri, Gell, Peter, Perga, Marie-Elodie, Jeppesen, Erik, Grundell, Rosie, Weller, Sandra, Zawadzki, Atun, Barry, Linda
- Authors: Kattel, Giri , Gell, Peter , Perga, Marie-Elodie , Jeppesen, Erik , Grundell, Rosie , Weller, Sandra , Zawadzki, Atun , Barry, Linda
- Date: 2015
- Type: Text , Journal article
- Relation: Freshwater Biology Vol. 60, no. 4 (2015), p. 711-723
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- Description: The palaeoecological assessment, and the use of stable isotopes of carbon in subfossils of herbivores and omnivores, represents a novel approach to understand transitions in past food-web structure and the dynamics of lake ecosystems in response to natural perturbations and human impacts. Combined with records of subfossil assemblages of cladocerans and chironomids, it may be possible to decipher whether changes are attributable to external forces or internally derived system shifts. A sediment record taken from the shallow (2.3 m depth) Kings Billabong in the River Murray floodplain (Australia) was analysed to explore changes in trophic dynamics over the past century. The palaeoecological assessment revealed that littoral assemblages of cladocerans and benthic diatoms were gradually replaced by planktonic (planktonic and facultative planktonic) assemblages after river regulation in the 1920s. The stable isotopic composition of carbon (
- Authors: Kattel, Giri , Gell, Peter , Perga, Marie-Elodie , Jeppesen, Erik , Grundell, Rosie , Weller, Sandra , Zawadzki, Atun , Barry, Linda
- Date: 2015
- Type: Text , Journal article
- Relation: Freshwater Biology Vol. 60, no. 4 (2015), p. 711-723
- Full Text:
- Reviewed:
- Description: The palaeoecological assessment, and the use of stable isotopes of carbon in subfossils of herbivores and omnivores, represents a novel approach to understand transitions in past food-web structure and the dynamics of lake ecosystems in response to natural perturbations and human impacts. Combined with records of subfossil assemblages of cladocerans and chironomids, it may be possible to decipher whether changes are attributable to external forces or internally derived system shifts. A sediment record taken from the shallow (2.3 m depth) Kings Billabong in the River Murray floodplain (Australia) was analysed to explore changes in trophic dynamics over the past century. The palaeoecological assessment revealed that littoral assemblages of cladocerans and benthic diatoms were gradually replaced by planktonic (planktonic and facultative planktonic) assemblages after river regulation in the 1920s. The stable isotopic composition of carbon (
Emerging threats and persistent conservation challenges for freshwater biodiversity
- Reid, Andrea, Carlson, Andrew, Creed, Irena, Eliason, Erika, Gell, Peter, Johnson, Pieter, Kidd, Karen, MacCormack, Tyson, Olden, Julian, Ormerod, Steve, Smol, John, Taylor, William, Tockner, Klement, Vermaire, Jesse, Dudgeon, David, Cooke, Steven
- Authors: Reid, Andrea , Carlson, Andrew , Creed, Irena , Eliason, Erika , Gell, Peter , Johnson, Pieter , Kidd, Karen , MacCormack, Tyson , Olden, Julian , Ormerod, Steve , Smol, John , Taylor, William , Tockner, Klement , Vermaire, Jesse , Dudgeon, David , Cooke, Steven
- Date: 2019
- Type: Text , Journal article
- Relation: Biological Reviews Vol. 94, no. 3 (2019), p. 849-873
- Full Text: false
- Reviewed:
- Description: In the 12 years since Dudgeon et al. (2006) reviewed major pressures on freshwater ecosystems, the biodiversity crisis in the world's lakes, reservoirs, rivers, streams and wetlands has deepened. While lakes, reservoirs and rivers cover only 2.3% of the Earth's surface, these ecosystems host at least 9.5% of the Earth's described animal species. Furthermore, using the World Wide Fund for Nature's Living Planet Index, freshwater population declines (83% between 1970 and 2014) continue to outpace contemporaneous declines in marine or terrestrial systems. The Anthropocene has brought multiple new and varied threats that disproportionately impact freshwater systems. We document 12 emerging threats to freshwater biodiversity that are either entirely new since 2006 or have since intensified: (i) changing climates; (ii) e-commerce and invasions; (iii) infectious diseases; (iv) harmful algal blooms; (v) expanding hydropower; (vi) emerging contaminants; (vii) engineered nanomaterials; (viii) microplastic pollution; (ix) light and noise; (x) freshwater salinisation; (xi) declining calcium; and (xii) cumulative stressors. Effects are evidenced for amphibians, fishes, invertebrates, microbes, plants, turtles and waterbirds, with potential for ecosystem-level changes through bottom-up and top-down processes. In our highly uncertain future, the net effects of these threats raise serious concerns for freshwater ecosystems. However, we also highlight opportunities for conservation gains as a result of novel management tools (e.g. environmental flows, environmental DNA) and specific conservation-oriented actions (e.g. dam removal, habitat protection policies, managed relocation of species) that have been met with varying levels of success. Moving forward, we advocate hybrid approaches that manage fresh waters as crucial ecosystems for human life support as well as essential hotspots of biodiversity and ecological function. Efforts to reverse global trends in freshwater degradation now depend on bridging an immense gap between the aspirations of conservation biologists and the accelerating rate of species endangerment.
Accounting for cryptic population substructure enhances detection of inbreeding depression with genomic inbreeding coefficients: an example from a critically endangered marsupial
- Zilko, Joseph, Harley, Dan, Hansen, Birgita, Pavlova, Alexandra, Sunnucks, Paul
- Authors: Zilko, Joseph , Harley, Dan , Hansen, Birgita , Pavlova, Alexandra , Sunnucks, Paul
- Date: 2020
- Type: Text , Journal article
- Relation: Molecular Ecology Vol. 29, no. 16 (2020), p. 2978-2993
- Full Text:
- Reviewed:
- Description: Characterizing inbreeding depression in wildlife populations can be critical to their conservation. Coefficients of individual inbreeding can be estimated from genome-wide marker data. The degree to which sensitivity of inbreeding coefficients to population genetic substructure alters estimates of inbreeding depression in wild populations is not well understood. Using generalized linear models, we tested the power of two frequently used inbreeding coefficients that are calculated from genome-wide SNP markers, FH and F^III, to predict four fitness traits estimated over two decades in an isolated population of the critically endangered Leadbeater's possum. FH estimates inbreeding as excess observed homozygotes relative to equilibrium expectations, whereas F^III quantifies allelic similarity between the gametes that formed an individual, and upweights rare homozygotes. We estimated FH and F^III from 1,575 genome-wide SNP loci in individuals with fitness trait data (N = 179–237 per trait), and computed revised coefficients, FHby group and F^IIIby group, adjusted for population genetic substructure by calculating them separately within two different genetic groups of individuals identified in the population. Using FH or F^III in the models, inbreeding depression was detected for survival to sexual maturity, longevity and whether individuals bred during their lifetime. F^IIIby group (but not FHby group) additionally revealed significant inbreeding depression for lifetime reproductive output (total offspring assigned to each individual). Estimates of numbers of lethal equivalents indicated substantial inbreeding load, but differing between inbreeding estimators. Inbreeding depression, declining population size, and low and declining genetic diversity suggest that genetic rescue may assist in preventing extinction of this unique Leadbeater's possum population. © 2020 John Wiley & Sons Ltd
- Authors: Zilko, Joseph , Harley, Dan , Hansen, Birgita , Pavlova, Alexandra , Sunnucks, Paul
- Date: 2020
- Type: Text , Journal article
- Relation: Molecular Ecology Vol. 29, no. 16 (2020), p. 2978-2993
- Full Text:
- Reviewed:
- Description: Characterizing inbreeding depression in wildlife populations can be critical to their conservation. Coefficients of individual inbreeding can be estimated from genome-wide marker data. The degree to which sensitivity of inbreeding coefficients to population genetic substructure alters estimates of inbreeding depression in wild populations is not well understood. Using generalized linear models, we tested the power of two frequently used inbreeding coefficients that are calculated from genome-wide SNP markers, FH and F^III, to predict four fitness traits estimated over two decades in an isolated population of the critically endangered Leadbeater's possum. FH estimates inbreeding as excess observed homozygotes relative to equilibrium expectations, whereas F^III quantifies allelic similarity between the gametes that formed an individual, and upweights rare homozygotes. We estimated FH and F^III from 1,575 genome-wide SNP loci in individuals with fitness trait data (N = 179–237 per trait), and computed revised coefficients, FHby group and F^IIIby group, adjusted for population genetic substructure by calculating them separately within two different genetic groups of individuals identified in the population. Using FH or F^III in the models, inbreeding depression was detected for survival to sexual maturity, longevity and whether individuals bred during their lifetime. F^IIIby group (but not FHby group) additionally revealed significant inbreeding depression for lifetime reproductive output (total offspring assigned to each individual). Estimates of numbers of lethal equivalents indicated substantial inbreeding load, but differing between inbreeding estimators. Inbreeding depression, declining population size, and low and declining genetic diversity suggest that genetic rescue may assist in preventing extinction of this unique Leadbeater's possum population. © 2020 John Wiley & Sons Ltd
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