Freshwater Science最新文献

{"title":"Quantifying spatial and temporal relationships between diatoms and nutrients in streams strengthens evidence of nutrient effects from monitoring data.","authors":"Lester L Yuan,&nbsp;Nathan J Smucker,&nbsp;Christopher T Nietch,&nbsp;Erik M Pilgrim","doi":"10.1086/718631","DOIUrl":"https://doi.org/10.1086/718631","url":null,"abstract":"<p><p>Observational data are frequently used to better understand the effects of changes in P and N on stream biota, but nutrient gradients in streams are usually associated with gradients in other environmental factors, a phenomenon that complicates efforts to accurately estimate the effects of nutrients. Here, we propose a new approach for analyzing observational data in which we compare the effects of changes in nutrient concentrations in time within individual sites and in space among many sites. Covarying relationships between other, potentially confounding environmental factors and nutrient concentrations are unlikely to be the same in both time and space, and, therefore, estimated effects of nutrients that are similar in time and space are more likely to be accurate. We applied this approach to diatom <i>rbcL</i> metabarcoding data collected from streams in the East Fork of the Little Miami River watershed, Ohio, USA. Changes in diatom assemblage composition were consistently associated with changes in the concentration of total reactive P in both time and space. In contrast, despite being associated with spatial differences in ammonia and urea concentrations, diatom assemblage composition was not associated with temporal changes in these nitrogen species. We suggest that the results of this analysis provide evidence of a causal effect of increased P on diatom assemblage composition. We further analyzed the effects of temporal variability in measurements of total reactive P and found that averaging periods greater than ~1 wk prior to sampling best represented the effects of P on the diatom assemblage. Comparisons of biological responses in space and time can sharpen insights beyond those that are based on analyses conducted on only 1 of the 2 dimensions.</p>","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9132200/pdf/nihms-1805451.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10600687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lessons learned from 20 y of monitoring suburban development with distributed stormwater management in Clarksburg, Maryland, USA","authors":"K. Hopkins, S. Woznicki, B. Williams, Charles C. Stillwell, Eric Naibert, M. Metes, Daniel K. Jones, D. Hogan, Natalie C. Hall, R. Fanelli, A. Bhaskar","doi":"10.1086/719360","DOIUrl":"https://doi.org/10.1086/719360","url":null,"abstract":"Urban development is a well-known stressor for stream ecosystems, presenting a challenge to managers tasked with mitigating its effects. For the past 20 y, streamflow, water quality, geomorphology, and benthic communities were monitored in 5 watersheds in Montgomery County, Maryland, USA. This study presents a synthesis of multiple studies of monitoring efforts in the study area and new analysis of more recent monitoring data to document the primary lessons learned from monitoring. The monitored watersheds include a forested control, an urban control with centralized stormwater management, and 3 suburban treatment watersheds featuring low-impact development and a high density of infiltration-focused stormwater facilities distributed across the watershed. Treatment watersheds were monitored before development, during construction, and after development. Monitoring was initiated to inform adaptive management of stormwater and impervious cover limits within the study area, with a focus on the impacts of distributed stormwater management. Results from our synthesis indicate that distributed stormwater management is advantageous compared with centralized stormwater management in numerous ways. Hydrologic benefits were greater with distributed stormwater infrastructure, demonstrating the ability to mitigate runoff volumes and peak flows and, for small storms, replicate predevelopment conditions. Baseflow temporarily increased during the construction phase in the treatment watersheds. Water-quality benefits were mixed, with declines in baseflow nitrate concentrations but limited changes to nitrate export and increases in specific conductance after development. Substantial topographic changes occurred during construction in the treatment watersheds, including changes within the riparian zone, despite riparian buffer protections. Ecological monitoring indicated that even though index of biotic integrity scores rebounded in some cases, sensitive benthic macroinvertebrate families did not fully recover in the treatment watersheds. Lessons learned from this synthesis highlight the importance of tracking multiple indicators of stream health and considering past land use and that more stormwater facilities distributed across the watershed is beneficial but cannot mitigate the effects of all urban stressors on aquatic ecosystems.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44188825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Periphyton C and N stable isotopes detect agricultural stressors in low-order streams","authors":"Sarah B. Whorley, J. Wehr","doi":"10.1086/719187","DOIUrl":"https://doi.org/10.1086/719187","url":null,"abstract":"Shifts in the stable isotope signatures of C and N in ecological materials have the potential to indicate environmental disturbances. This study examined the δ13C‰ and δ15N‰ ratios of stream water and periphyton from low-order streams in a landscape influenced by agricultural activities. Our key purpose was to assess the influence of best management practice (BMP) presence and age on C and N isotope values as a potential water-quality assessment. We collected stream water and periphyton from 19 streams within the Upper Delaware River watershed in New York, USA, in each of 4 management categories: 1) recently applied BMP treatments, 2) long-standing BMPs, 3) streams lacking BMPs, and 4) minimally disturbed reference streams. We sampled and analyzed water and periphyton for δ13C‰ and δ15N‰ in a repeated-measures design (BMP category × time) from April to November 2013. There were large seasonal differences in stream water δ13C-dissolved organic C (DIC)‰ and δ15NO3-N‰, with strong differences between reference and agricultural streams. Periphyton δ13C‰ and δ15N‰ values also differed strongly across streams draining land with agricultural activities, with 85% higher periphyton δ15N‰ signals in all agricultural categories vs reference streams. Periphyton diatom and chlorophyte taxonomic proportions showed the strongest relationship with periphyton δ13C‰ values, where diatoms were negatively associated with increasing δ13C‰. These results suggest that aqueous and periphytic stable isotopes were sensitive in detecting persistent effects of agriculture on these streams despite BMP mitigation, where nutrient (orthosphosphate, nitrite, and ammonia) levels were non-indicative. These results also suggest that BMPs may not have fully eliminated the negative impacts of agricultural stressors on water quality in impacted streams.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49555538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of impoundments on stream crayfish assemblages","authors":"Zanethia C. Barnett, S. Adams, J. Hoeksema, G. Easson, Clifford A. Ochs","doi":"10.1086/719051","DOIUrl":"https://doi.org/10.1086/719051","url":null,"abstract":"Life-history timing, trophic interactions, and colonization potential of stream benthos are linked to a stream’s flow regime. Modifications to flow regimes often alter the composition of benthic assemblages. We assessed the impacts of relatively large storage dams (>15 m in height, >400-ha impoundments) on crayfish assemblages in southern Appalachian Mountain streams, Alabama, USA. We sampled crayfishes at multiple sites in flowing sections upstream and downstream of dams in 3 impounded streams and along similar lengths of 2 unimpounded streams in the Bear Creek and Cahaba River drainages. We analyzed at 2 scales: within and between drainages. This multi-scale approach allowed us to assess the effects of impoundments on crayfish assemblages in 1 drainage and then assess whether impoundment effects could be generalized across drainages. We compared crayfish assemblages between impounded and unimpounded streams and examined changes in crayfish assemblages with distance from impoundments, considering land-use history as a potential confounding factor. Adult densities averaged 45% higher, and sizes 10% smaller, in downstream sections of unimpounded streams compared with impounded streams. Densities and sizes of adults in upstream sections did not differ between unimpounded and impounded streams. In both drainages, unimpounded stream crayfish assemblage structure gradually shifted along the stream length, with species present upstream differing from those present downstream. Conversely, in all impounded streams, species assemblages did not differ between upstream and downstream sections, illustrating that dams diminish crayfish diversity. Nonetheless, finer-scale assessments showed that crayfish density and richness increased with distance downstream of impoundments. This suggests that assemblage recovery is possible with increasing distance downstream of impoundments. Additionally, we detected fewer crayfish assemblage differences between impounded and unimpounded streams in the Cahaba River drainage than the Bear Creek drainage. In the Cahaba River drainage, urbanization and the presence of an invasive crayfish species in both streams may have hindered our ability to distinguish impoundment effects on crayfishes. Our results show that large dams negatively affect crayfishes and may affect hundreds of crayfish species in thousands of stream km, possibly altering stream systems by interfering with the numerous ecosystem functions influenced by crayfishes.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44493037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hatching dynamics of invertebrate dormant stages in temporary ponds are influenced by multiple hydrations","authors":"D. Vendramin, M. M. Pires, R. F. Freiry, A. Schneider, Lidiane Martins, E. S. Medeiros, O. Rocha, C. Stenert, L. Maltchik","doi":"10.1086/719129","DOIUrl":"https://doi.org/10.1086/719129","url":null,"abstract":"Dormancy termination in aquatic invertebrates depends on multiple environmental cues, notably hydration, and on the invertebrates’ ability to respond to each new flooding event. Hatching of dormant stages is important to ecological processes in intermittent wetlands, such as recolonization of biota after dry periods and maintenance of foodweb dynamics. However, hatching responses of invertebrates to hydration cues can show considerable spatial and taxonomic variation, and consequences of this variation to the hatchling assemblage structure are still unclear. In this study, we tested how multiple hydrations in series affect hatching dynamics and assemblage structure of invertebrate fauna that hatch from sediments of temporary ponds. We hypothesized that variable responses to flooding among taxa would influence the hatchling assemblage structure. We predicted that hatchling richness would show little or no variation across hydration events but that hatchling composition would vary among hydration events. We performed an ex-situ hatching experiment to expose the sediments of 12 temporary ponds in the southern Brazilian Coastal Plain to a sequence of 3 hydration events and to induce hatching of invertebrates from dormant stages in the sediments. Hatchling composition, but not richness, differed among the 3 hydration events. Additionally, hatchling composition showed marked short-term variation within each hydration event. We showed that dormancy dynamics of aquatic invertebrates in subtropical temporary ponds are influenced by multiple hydration cues. Our results have important implications for biodiversity assessment and management of temporary ponds and for understanding the effects of changing hydrologic regimes on the ecological processes of intermittently flooded ecosystems.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46483416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Response of nutrient limitation to invasive fish suppression: How carcasses and analog pellets alter periphyton","authors":"Dominique R. Lujan, Lusha M. Tronstad, M. A. Briggs, L. K. Albertson, H. C. Glassic, C. S. Guy, T. Koel","doi":"10.1086/718647","DOIUrl":"https://doi.org/10.1086/718647","url":null,"abstract":"The native Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri Jordan and Gilbert, 1883) population in Yellowstone Lake, Yellowstone National Park, Wyoming, USA, is in decline because of competition from the introduced, invasive Lake Trout (Salvelinus namaycush Walbaum in Artedi, 1792). Gillnetting is used to suppress adult Lake Trout; however, methods are being developed to suppress embryos, including adding Lake Trout carcasses and carcass-analog pellets to spawning sites. Decomposing carcasses and analog pellets cause decreased dissolved oxygen concentrations thereby leading to Lake Trout embryo mortality, but the effects of these methods on primary producers are unknown. We deployed in-situ nutrient diffusing substrates (NDS) at 3 spawning sites. The 1st site was treated with carcasses, the 2nd site was treated with analog pellets, and a 3rd lacked treatment (control). To estimate how suppression measures may alter nutrient limitation, we measured algal biomass in 6 NDS amendments at each site: nothing (control), N, P, N + P, ground carcasses, or pulverized analog pellets. We deployed 5 replicates of each amendment at each site before and after treating whole sites. N and P co-limited periphyton before carcasses or analog pellets were added to spawning sites (p < 0.01); however, nutrients were not limiting after the treatments were added to spawning sites (p = 0.31–1). Algal biomass was 4× higher after whole-site carcass treatments. In contrast, analog pellets appeared to suppress algal biomass in the amendments (20% of NDS at the control site post-treatment) and in the treatment plot (33% of pre-treatment biomass at analog pellet site). We also measured how individual ingredients in analog pellets altered periphyton biomass, which suggested that vitamin E, estrogen, and soybean oil ingredients reduced the growth of primary producers. Suppression methods may stimulate or reduce algal biomass, depending on the methods used, which could have cascading effects on food webs and potentially reduce the success of the control measures. Estimating how different Lake Trout suppression methods may alter basal resources in the littoral zone of Yellowstone Lake will help natural resource agencies develop effective plans to control invasive predators at early life stages while minimally altering ecosystems.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45508371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of temperature and light on ecosystem metabolism in a Japanese stream","authors":"D. Nakano, Tomoya Iwata, Jumpei Suzuki, Teruhisa Okada, Ryosuke Yamamoto, M. Imamura","doi":"10.1086/718648","DOIUrl":"https://doi.org/10.1086/718648","url":null,"abstract":"Ecosystem metabolism is a fundamental process that governs biogeochemical C cycling through the fixation and mineralization of C by all the organisms in a system; however, the functional responses of ecosystem metabolism to light and temperature variability remain unknown in streams and rivers. In this study, we assessed the effects of temperature and light on ecosystem metabolism, namely gross primary production (GPP) and ecosystem respiration (ER), in a Japanese stream by monitoring the seasonal diel changes in dissolved oxygen. We found that the temperature dependence of metabolism, which is expressed as activation energy, was higher for ER (0.48 eV) than for GPP (0.39 eV), supporting the metabolic theory of ecology. Both daily GPP and ER increased with the daily integrated photosynthetically active radiation (PAR), peaking at moderate PAR values and decreasing at higher irradiance levels. This unimodal relationship between daily GPP and PAR was due to the rapid increase of instantaneous PAR during the early morning, suppressing the maximum rate of area-specific productivity, which was a main determinant of daily GPP. Moreover, daily GPP and ER were closely associated in this study stream, resulting in a unimodal pattern of daily ER with daily integrated PAR. Our results suggest that both temperature and light regulate stream ecosystem metabolism but that the sunlight regime (i.e., the rapid increase of solar irradiance in the early morning) rather than light intensity per se may be a critical factor for both GPP and ER in the study stream.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44045016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The contribution of autochthonous resource to the diet of aquatic consumers is unrelated to its spatial distribution in tank bromeliads","authors":"Juliana S. Leal, Angélica L. González, Rhuana C. Paulo, V. Farjalla","doi":"10.1086/718630","DOIUrl":"https://doi.org/10.1086/718630","url":null,"abstract":"Autochthonous biomass is heterogeneously distributed within freshwater ecosystems, shaping community structure and ecosystem functioning, yet few studies have evaluated how the spatial heterogeneity in the availability of the autochthonous resource affects its contribution to the diets of aquatic consumers. To fill this gap, we conducted a field survey to test whether the spatial heterogeneity of the autochthonous resource within freshwater ecosystems formed in tank bromeliads determines its contribution to the diet of aquatic consumers. Tank bromeliads are Neotropical plants with densely arranged leaves in a rosette shape that accumulate rainwater and terrestrial plant material, providing suitable habitat for a diversity of aquatic invertebrates. We sampled 3 regions (north, central, and south) of the bromeliad ecosystem to provide a natural gradient in the availability of the autochthonous resource (i.e., algae biomass). To trace the diets of aquatic consumers, we used stable isotope analysis of hydrogen coupled with Bayesian stable isotope mixing models. The availability of the autochthonous resource varied among the tank-bromeliad regions with light availability, but it was not related to its relative contribution to the diets of aquatic consumers. Instead, aquatic consumers from all regions showed similarly high degrees of autochthony. The capacity of aquatic consumers to move within the plant did not affect the contribution of the autochthonous resource to their diets. We reason that the contribution of the autochthonous resource to the diets of consumers is not related to its spatial distribution because aquatic consumers preferentially feed on this resource, even when its stocks are limited. In addition, water flow among tanks could provide a subsidy of the autochthonous resource from more productive to less productive regions. We conclude that spatial heterogeneity in the availability of the autochthonous resource does not limit its contribution to the diet of aquatic consumers because of active foraging on the autochthonous resource and the flux of this resource among compartments in freshwater tank-bromeliad ecosystems.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43568571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wildfire effects on mass and thermal tolerance of Hydropsyche oslari (Trichoptera) in southwestern USA montane grassland streams","authors":"Lauren B. Kremer, C. Caldwell","doi":"10.1086/718556","DOIUrl":"https://doi.org/10.1086/718556","url":null,"abstract":"Large-scale disturbances, such as wildfire, can markedly affect streams for years. As terrestrial areas within a watershed slowly recover, stream environments and biota can experience repeated and long-lasting challenges. In 2011, the Las Conchas wildfire burned 1/3 of the Valles Caldera National Preserve in northern New Mexico, USA. Seven y post-fire, streams located near the burn perimeter continue to experience varying levels of alteration (e.g., channel alteration with large diel temperature swings), whereas the terrestrial uplands have begun to recover. Extreme temperatures in stream systems may affect the aquatic community, including ectotherms such as caddisflies. These post-fire temperature ranges may increase an ectotherm’s breadth of thermal adaptation, but at metabolic costs that diminish organismal performance, such as growth, development, and fecundity. In this study we characterized in-situ effects of varied thermal regimes across preserve streams on the performance of the caddisfly Hydropsyche oslari Banks, 1905. We measured mass and critical thermal maximum (CTmax) in H. oslari larvae from preserve streams affected by wildfire (high temperature range) and in streams minimally affected by wildfire (low temperature range). We predicted that increased daily temperature maxima and reduced daily temperature minima (i.e., large diel temperature swings) would be associated with reduced H. oslari mass because of the limiting effects of suboptimal temperatures on growth. As predicted, in the weeks prior to their emergence as terrestrial adults, 5th-instar larvae within the high-temperature range stream had reduced mass (mean 3.3 ± SE 0.55 mg) relative to larvae from the low-temperature range stream (6.2 ± 0.69 mg). We also predicted that CTmax of H. oslari would reflect stream thermal history. Indeed, larvae H. oslari from the high-temperature range stream exhibited increased CTmax (35.4 ± 0.17°C) compared with larvae from the low-temperature range stream (34.4 ± 0.28°C). We demonstrated that the effects of wildfire on caddisflies can be long lasting, as evidenced by the reduced size at maturity and higher thermal tolerance in a caddisfly population 7 y post-fire.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48585638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental factors structuring diatom assemblages in thermo-mineral springs of Sardinia, Italy","authors":"G. Lai, L. Ector, C. E. Wetzel, A. Lugliè, B. Padedda","doi":"10.1086/718555","DOIUrl":"https://doi.org/10.1086/718555","url":null,"abstract":"Thermal springs provide natural laboratories to test the responses of biological communities to various stressors. To date, little is known about how water temperature and chemistry influence the microalgal assemblages in these ecosystems, especially in the circum-Mediterranean area. In this study, we assessed the environmental drivers of benthic diatom assemblages collected from different substrates in 8 thermo-mineral springs of Sardinia, Italy, with a focus on temperature and conductivity. A total of 205 diatom species (67 genera) were found, of which 12 (8 genera) were centric and 193 (59 genera) were pennate. Composition of diatom assemblages was associated with temperature, pH, conductivity, bicarbonates (HCO3−), and sulfates (SO42−). Multivariate analyses also confirmed differences in species composition, richness, diversity, and evenness of diatom assemblages from groups of springs distinguished by temperature and conductivity gradients. We found higher species richness, diversity, and evenness in hyperthermal (water temperature = 52.7−71.5°C) and medium-mineral springs (conductivity = 590−1193 µS/cm). Our results indicate that thermal springs are not always inhospitable environments for diatoms. Springs with high water temperatures hosted rich and diverse diatom assemblages, likely thanks to their ecotonal nature and a combination of multiple local factors.","PeriodicalId":48926,"journal":{"name":"Freshwater Science","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47255281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}