المؤلفون: Beatrice S. Dewenter, Alisha A. Shah, Jane Hughes, N. LeRoy Poff, Ross Thompson, Ben J. Kefford

المصدر: Ecology and Evolution, Vol 14, Iss 2, Pp n/a-n/a (2024)

مصطلحات موضوعية: aquatic ectotherms, climate change, climate variability hypothesis, CTmax, CTmin, temperature variability, Ecology, QH540-549.5

الوصف: Abstract Climate change involves increases in mean temperature and changes in temperature variability at multiple temporal scales but research rarely considers these temporal scales. The climate variability hypothesis (CVH) provides a conceptual framework for exploring the potential effects of annual scale thermal variability across climatic zones. The CVH predicts ectotherms in temperate regions tolerate a wider range of temperatures than those in tropical regions in response to greater annual variability in temperate regions. However, various other aspects of thermal regimes (e.g. diel variability), organisms' size and taxonomic identity are also hypothesised to influence thermal tolerance. Indeed, high temperatures in the tropics have been proposed as constraining organisms' ability to tolerate a wide range of temperatures, implying that high annual maximum temperatures would be associated with tolerating a narrow range of temperatures. We measured thermal regimes and critical thermal limits (CTmax and CTmin) of freshwater insects in the orders Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies) along elevation gradients in streams in temperate and tropical regions of eastern Australia and tested the CVH by determining which variables were most correlated with thermal breadth (Tbr = CTmax − CTmin). Consistent with the CVH, Tbr tended to increase with increasing annual temperature range. Tbr also increased with body size and Tbr was generally wider in Plecoptera than in Ephemeroptera or Trichoptera. We also find some support for a related hypothesis, the climate extreme hypothesis (CEH), particularly for predicting upper thermal limits. We found no evidence that higher annual maximum temperature constrained individuals' abilities to tolerate a wide range of temperatures. The support for the CVH we document suggests that temperate organisms may be able to tolerate wider ranges of temperatures than tropical organisms. There is an urgent need to investigate other aspects of thermal regimes, such as diel temperature cycling and minimum temperature.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2045-7758Test

الوصول الحر: https://doaj.org/article/27f33f57d163497badde289af31649eaTest

المؤلفون: Ben J. Kefford, Ross V. Hyne, Andrew J. Brooks, Jonathan P. Bray, Mark Shenton, Kasey Hills, Susan J. Nichols

المصدر: Limnology and Oceanography Letters, Vol 8, Iss 1, Pp 181-189 (2023)

مصطلحات موضوعية: Oceanography, GC1-1581

الوصف: Abstract Human‐mediated salinity increases are occurring in freshwaters globally, with consequent negative effects on freshwater biodiversity. Salinity comprises multiple anions and cations. While total concentrations are typically used to infer effects, individual ion concentrations and ion ratios are critical in determining effects. Moreover, estimates of toxicity from single‐species laboratory tests, may not accurately predict relative effects on populations and communities. Here, we compared salinity increases from synthetic marine salts and sodium bicarbonate in an outdoor mesocosm experiment in southeastern Australia. We found different effects of salt types on stream macroinvertebrates at the population and community levels, where similar effects were predicted from single‐species laboratory tests. Our results caution against the use of single‐species laboratory‐derived toxicological data to predict both environmentally safe salinity levels and the relative effects of different salt sources on freshwater biodiversity.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2378-2242Test

الوصول الحر: https://doaj.org/article/d89b9d34618d4e34a8d3dd16563ab0ddTest

المؤلفون: Lloyd P. Werry, Mirco Bundschuh, Simon M. Mitrovic, Richard P. Lim, Ben J. Kefford

المصدر: Ecology and Evolution, Vol 12, Iss 10, Pp n/a-n/a (2022)

مصطلحات موضوعية: litter, macroinvertebrates, organic matter, water temperature, Ecology, QH540-549.5

الوصف: Abstract The breakdown of allochthonous organic matter, is a central step in nutrient cycling in stream ecosystems. There is concern that increased temperatures from climate change will alter the breakdown rate of organic matter, with important consequences for the ecosystem functioning of alpine streams. This study investigated the rate of leaf litter breakdown and how temperature and other factors such as microbial and invertebrate activities influenced this over elevational and temporal gradients. Dried leaves of Snow Gum (Eucalyptus pauciflora) and cotton strips were deployed in coarse (6 mm), and fine (50 μm) mesh size bags along an 820 m elevation gradient. Loss of mass in leaf litter and cotton tensile strength per day (k per day), fungal biomass measured as ergosterol concentration, invertebrate colonization of leaf litter, and benthic organic matter (mass and composition) were determined. Both microbial and macroinvertebrate activities were equally important in leaf litter breakdown with the abundance of shredder invertebrate taxa. The overall leaf litter breakdown rate and loss of tensile strength in cotton strips (both k per day) were greater during warmer deployment periods and at lower elevations, with significant positive relationships between mean water temperature and leaf breakdown and loss of tensile strength rate, but no differences between sites, after accounting for the effects of temperature. Despite considerably lower amounts of benthic organic matter in streams above the tree line relative to those below, shredders were present in coarse mesh bags at all sites. Ergosterol concentration was greater on leaves in coarse mesh bags than in fine mesh bags, implying differences in the microbial communities. The importance of water temperatures on the rate of leaf litter breakdown suggests the potential effects of climate change‐induced temperature increases on ecological processes in such streams.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2045-7758Test

الوصول الحر: https://doaj.org/article/907156bcd86146028cd50bd2c06f7860Test

المؤلفون: Renee Dowse, Carolyn G. Palmer, Kasey Hills, Fraser Torpy, Ben J. Kefford

المصدر: Royal Society Open Science, Vol 4, Iss 1 (2017)

مصطلحات موضوعية: ephemeroptera, mayfly, osmolality, osmoregulation, salinization, Science

الوصف: Osmoregulation is a key physiological function, critical for homeostasis. The basic physiological mechanisms of osmoregulation are thought to be well established. However, through a series of experiments exposing the freshwater mayfly nymph Austrophlebioides pusillus (Ephemeroptera) to increasing salinities, we present research that challenges the extent of current understanding of the relationship between osmoregulation and mortality. A. pusillus had modelled 96 h LC10, LC50 and LC99 of 2.4, 4.8 and 10 g l−1 added synthetic marine salt (SMS), respectively. They were strong osmoregulators. At aquarium water osmolality of 256 ± 3.12 mmol kg−1 (±s.e.; equivalent to 10 g l−1 added SMS), the haemolymph osmolality of A. pusillus was a much higher 401 ± 4.18 mmol kg−1 (±s.e.). The osmoregulatory capacity of A. pusillus did not break down, even at the salinity corresponding to their LC99, thus their mortality at this concentration is due to factors other than increased internal osmotic pressure. No freshwater invertebrate has been previously reported as suffering mortality from rises in salinity that are well below the iso-osmotic point. Recently, studies have reported reduced abundance/richness of Ephemeroptera with slightly elevated salinity. Given that salinization is an increasing global threat to freshwaters, there is an urgent need for studies into the osmophysiology of the Ephemeroptera to determine if their loss at locations with slightly elevated salinity is a direct result of external salinity or other, possibly physiological, causes.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2054-5703Test

الوصول الحر: https://doaj.org/article/3858a285587f4ec79b166f91bfc02993Test

المؤلفون: Maria João Feio, Robert M. Hughes, Sónia R. Q. Serra, Susan J. Nichols, Ben J. Kefford, Mark Lintermans, Wayne Robinson, Oghenekaro N. Odume, Marcos Callisto, Diego R. Macedo, Jon S. Harding, Adam G. Yates, Wendy Monk, Keigo Nakamura, Terutaka Mori, Masanao Sueyoshi, Norman Mercado‐Silva, Kai Chen, Min Jeong Baek, Yeon Jae Bae, Ram Devi Tachamo‐Shah, Deep Narayan Shah, Ian Campbell, Nabor Moya, Francis O. Arimoro, Unique N. Keke, Renato T. Martins, Carlos B. M. Alves, Paulo S. Pompeu, Subodh Sharma

المصدر: Global Change Biology. 29:355-374

مصطلحات موضوعية: Global and Planetary Change, Ecology, Environmental Chemistry, General Environmental Science

الوصف: Rivers suffer from multiple stressors acting simultaneously on their biota, but the consequences are poorly quantified at the global scale. We evaluated the biological condition of rivers globally, including the largest proportion of countries from the Global South published to date. We gathered macroinvertebrate- and fish-based assessments from 72,275 and 37,676 sites, respectively, from 64 study regions across six continents and 45 nations. Because assessments were based on differing methods, different systems were consolidated into a 3-class system: Good, Impaired, or Severely Impaired, following common guidelines. The proportion of sites in each class by study area was calculated and each region was assigned a Köppen-Geiger climate type, Human Footprint score (addressing landscape alterations), Human Development Index (HDI) score (addressing social welfare), % rivers with good ambient water quality, % protected freshwater key biodiversity areas; and % of forest area net change rate. We found that 50% of macroinvertebrate sites and 42% of fish sites were in Good condition, whereas 21% and 29% were Severely Impaired, respectively. The poorest biological conditions occurred in Arid and Equatorial climates and the best conditions occurred in Snow climates. Severely Impaired conditions were associated (Pearson correlation coefficient) with higher HDI scores, poorer physico-chemical water quality, and lower proportions of protected freshwater areas. Good biological conditions were associated with good water quality and increased forested areas. It is essential to implement statutory bioassessment programs in Asian, African, and South American countries, and continue them in Oceania, Europe, and North America. There is a need to invest in assessments based on fish, as there is less information globally and fish were strong indicators of degradation. Our study highlights a need to increase the extent and number of protected river catchments, preserve and restore natural forested areas in the catchments, treat wastewater discharges, and improve river connectivity.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b392ae1b69053fa24dd265c50f240ceeTest
https://doi.org/10.1111/gcb.16439Test

المؤلفون: Kasey A. Hills, Ross V. Hyne, Ben J. Kefford

المصدر: Ecotoxicology. 31:967-975

مصطلحات موضوعية: Ions, Bicarbonates, Coal, Health, Toxicology and Mutagenesis, Animals, Fresh Water, General Medicine, Sodium Chloride, Management, Monitoring, Policy and Law, Toxicology, Invertebrates, Ecosystem, Water Pollutants, Chemical

الوصف: Abstract Concentrations of major ions in coal mine discharge waters and unconventional hydrocarbon produced waters derived from coal bed methane (CBM) production, are potentially harmful to freshwater ecosystems. Bicarbonate is a major constituent of produced waters from CBM and coal mining. However, little is known about the relative toxicity of differing ionic proportions, especially bicarbonate, found in these CBM waters. As all freshwater invertebrates tested are more acutely sensitive to sodium bicarbonate (NaHCO3) than sodium chloride (NaCl) or synthetic sea water, we tested the hypotheses that toxicity of CBM waters are driven by bicarbonate concentration, and waters containing a higher proportion of bicarbonate are more toxic to freshwater invertebrates than those with less bicarbonate. We compared the acute (96 h) lethal toxicity to six freshwater invertebrate species of NaHCO3 and two synthetic CBM waters, with ionic proportions representative of water from CBM wells across New South Wales (NSW) and Queensland (Qld), in Australia. The ranking of LC50 values expressed as total salinity was consistent with the hypotheses. However, when toxicity was expressed as bicarbonate concentration, the hypothesis that the toxicity of coal bed waters would be explained by bicarbonate concentration was not well supported, and other ionic components were either ameliorating or exacerbating the NaHCO3 toxicity. Our findings showed NaHCO3 was more toxic than NaCl and that the NaHCO3 proportion of synthetic CBM waters drives toxicity, however other ions are altering the toxicity of bicarbonate.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2e443b7aba9864620df9f58cd5c31342Test
https://doi.org/10.1007/s10646-022-02552-4Test

المؤلفون: Benjamin J. G. Moulding, Guillaume Kon Kam King, Mark Shenton, Jon P. Bray, Susan J. Nichols, Ben J. Kefford

المصدر: Archives of Environmental Contamination and Toxicology. 82:281-293

مصطلحات موضوعية: Health, Toxicology and Mutagenesis, General Medicine, Toxicology, Pollution

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::fda43b71d6afdf04b1e1a3f0259ae837Test
https://doi.org/10.1007/s00244-021-00908-1Test

المؤلفون: J. Reich, Ross M. Thompson, Guillaume Kon Kam King, Jon P. Bray, Susan J. Nichols, Ben J. Kefford, Andrew O’Reilly-Nugent, Ralph Charles Mac Nally

المصدر: Marine and Freshwater Research. 73:140-146

مصطلحات موضوعية: Salinity, Ecology, Range (biology), Stressor, Ecosystem, Biota, Aquatic Science, Biology, Oceanography, Ecology, Evolution, Behavior and Systematics, Invertebrate

الوصف: Salinity is increasing in many naturally fresh waters because of human activities, and there are concerns about the ecological effects of these increases. Salinity, as with any stressor, can affect organisms both directly and indirectly. In a previous study (Bray et al. 2019), we evaluated the relative importance of direct and indirect effects of increased salinity on stream invertebrates. Chessman (2021) criticised that study, claiming that the biotic treatments were confounded and did not directly test the hypotheses. Chessman (2021) also conducted a reanalysis of the data. We show through the analysis of new data that our biotic treatments were not confounded and that the conclusions made by Chessman (2021) were probably a consequence of the low statistical power of his analysis. Consequently, we argue that Chessman’s (2021) comments do not substantively alter the conclusions of our study, and we provide more evidence to support the conclusions of our previous publication. The study of biota–stressor interactions is increasingly relevant to a wide range of global ecosystems. There is a need to develop tractable experimental and survey designs that address these problems, and we identify further avenues for study of these complex issues.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::4cc2390f22a691223bbad4f80176c9ecTest
https://doi.org/10.1071/mf21164Test

المؤلفون: Kasey A. Hills, Mark Shenton, Susan J. Nichols, Ross V. Hyne, Jonathan Bray, Andrew J. Brooks, Ben J. Kefford

المصدر: Limnology and Oceanography Letters. 8:181-189

مصطلحات موضوعية: Salinity, education.field_of_study, Single species, Population, Toxicity, Zoology, Aquatic Science, Biology, Oceanography, education

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::b5eece18e9b34ad38c57c61db63d74c2Test
https://doi.org/10.1002/lol2.10208Test

المؤلفون: Ben J. Kefford, Jon P. Bray, Susan J. Nichols, Jollene Reich, Ralph Mac Nally, Andrew O’Reilly-Nugent, Guillaume Kon Kam King, Ross Thompson

المصدر: Marine and Freshwater Research. 73:585-587

مصطلحات موضوعية: Ecology, Aquatic Science, Oceanography, Ecology, Evolution, Behavior and Systematics

الوصف: The most parsimonious interpretation of our experimental findings (Bray 2019; Kefford 2022) is that the effect of experimental increases in salinity on stream macroinvertebrate communities, was altered by organisms from a high-salinity site. This interpretation is consistent with long-established and widely accepted ecological and ecotoxicological theory. The suggestion (Chessman 2022) that the initial community was confounded, that it converged within the first week of the experiment and then diverged again, is neither parsimonious nor explicable by theory. All experiments are imperfect, yet we maintain that our experiment is informative, and we encourage other researchers to generate new data to inform on the degree to which abiotic and biotic effects of salinity, and other abiotic stressors, affect ecological communities.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::aac1401155f73a88eaf0bb82d295dd9aTest
https://doi.org/10.1071/mf22043Test