Research

17 pages, 3209 KiB

Open AccessFeature PaperArticle

Investigation of the Combined Effects of Rising Temperature and Pesticide Contamination on the Swimming Behaviour of Alpine Chironomids

by Valeria Lencioni, Valeria Di Nica and Sara Villa

Water 2021, 13(24), 3618; https://doi.org/10.3390/w13243618 - 16 Dec 2021

Cited by 5 | Viewed by 2142

Abstract

Some pollutants can be transported through the atmosphere and travel medium–long distances to be deposited in glaciers at high altitude and latitude. The increase in the rate of glacier melting due to global warming can release these pollutants in alpine streams. This study [...] Read more.

Some pollutants can be transported through the atmosphere and travel medium–long distances to be deposited in glaciers at high altitude and latitude. The increase in the rate of glacier melting due to global warming can release these pollutants in alpine streams. This study investigated the combined effects of rising temperatures and chlorpyrifos (CPF) contamination on the swimming behaviour of alpine chironomids collected in a shrinking alpine glacier. We assessed the individual and interaction effects of rising temperatures (2–11 °C) and CPF concentrations (0–110 ng L⁻¹) on the swimming behaviour of Diamesa zernyi (Chironomidae) larvae. Distance (mm) and speed (mm s⁻¹) were recorded using a video-tracking system after 24–72 h of treatment. The two stressors caused different effects on distance and speed, with increasing temperature generally causing hyperactivity and CPF from hyperactivity to reduced mobility. Two interactions were detected between stressors when combined: (i) CPF superimposed the effect of temperature on both behavioural endpoints i.e., with 110 ng L⁻¹ of CPF, at 11 °C, larvae moved less; (ii) warming (11 °C) magnified the negative effect of CPF: the smallest distance and slowest speed were recorded at the highest values of the two stressors after 72 h. Our results suggest that water contamination by CPF, even at sub-lethal concentrations, might increase the sensitivity of chironomids to warming, and vice versa, raising concerns about freshwater biodiversity conservation under climate change. Full article

(This article belongs to the Special Issue Effects of Climate and Environmental Change on Freshwater Ecosystems)

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16 pages, 1516 KiB

Open AccessFeature PaperArticle

Functional Feeding Groups of Macrofauna and Detritus Decomposition along a Gradient of Glacial Meltwater Influence in Tropical High-Andean Streams

by Patricio Andino, Rodrigo Espinosa, Verónica Crespo-Pérez, Sophie Cauvy-Frauníe, Olivier Dangles and Dean Jacobsen

Water 2021, 13(22), 3303; https://doi.org/10.3390/w13223303 - 22 Nov 2021

Cited by 5 | Viewed by 2542

Abstract

Tropical Andean glaciers are retreating rapidly, with possible consequences for trophic structure and ecosystem processes in high Andean meltwater streams. Here, we measured the environmental characteristics, quantified pools of particulate organic matter (POM) and periphyton (Chl. a), sampled benthic macroinvertebrates, determined functional feeding [...] Read more.

Tropical Andean glaciers are retreating rapidly, with possible consequences for trophic structure and ecosystem processes in high Andean meltwater streams. Here, we measured the environmental characteristics, quantified pools of particulate organic matter (POM) and periphyton (Chl. a), sampled benthic macroinvertebrates, determined functional feeding groups (FFG), and performed mesh bag decomposition experiments with Calamagrostis grass detritus at 17 stream sites along a gradient of glacial influence (GI) with 0–23% glacier cover in the catchment at 4050–4200 m a.s.l. in the Andes of Ecuador. POM was unrelated to GI while Chl. a. showed a weak (non-significant) negative relationship to GI. The macrofauna abundance decreased while taxon richness and the number of FFGs per site showed a hump-shaped relationship with increasing GI. Taxa with an opportunistic and generalist feeding mode generally dominated benthic assemblages and were related to high GI levels and low Chl. a. Only shredders were negatively related to GI, but unrelated to POM. Decomposition rates were comparable to those found in temperate alpine streams, and for both fine (0.0010–0.0065; median 0.0028 d⁻¹) and coarse (0.0019–0.0088; median 0.0048 d⁻¹) mesh bags, peaked at intermediate GI values, while the difference between bag types was small and almost constant along the GI gradient. This indicates an overall minor effect of macroinvertebrate shredders compared to that of microbes, in particular at high GI. It also suggests that the relatively high average temperature of these high-altitude equatorial streams (7–10 °C) does not produce higher decomposition rates than those in comparable but colder streams at temperate latitudes. The results suggest that, at the lower end of glacier cover, tropical glacier loss will not change the dominant microbial role in detritus decomposition, but that part of the physical abrasion could be partially replaced by biological shredding. Full article

(This article belongs to the Special Issue Effects of Climate and Environmental Change on Freshwater Ecosystems)

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13 pages, 1936 KiB

Open AccessArticle

Mesocosm Experiments Reveal Global Warming Accelerates Macrophytes Litter Decomposition and Alters Decomposition-Related Bacteria Community Structure

by Meng Pan, Tao Wang, Bowen Hu, Penglan Shi, Jun Xu and Min Zhang

Water 2021, 13(14), 1940; https://doi.org/10.3390/w13141940 - 14 Jul 2021

Cited by 8 | Viewed by 3091

Abstract

Global climate change scenarios predict that lake water temperatures will increase up to 4 °C and extreme weather events, such as heat waves and large temperature fluctuations, will occur more frequently. Such changes may result in the increase of aquatic litter decomposition and [...] Read more.

Global climate change scenarios predict that lake water temperatures will increase up to 4 °C and extreme weather events, such as heat waves and large temperature fluctuations, will occur more frequently. Such changes may result in the increase of aquatic litter decomposition and on shifts in diversity and structure of bacteria communities in this period. We designed a two-month mesocosm experiment to explore how constant (+4 °C than ambient temperature) and variable (randomly +0~8 °C than ambient temperature) warming treatment will affect the submerged macrophyte litter decomposition process. Our data suggests that warming treatments may accelerate the decomposition of submerged macrophyte litter in shallow lake ecosystems, and increase the diversity of decomposition-related bacteria with community composition changed the relative abundance of Proteobacteria, especially members of Alphaproteobacteria increased while that of Firmicutes (mainly Bacillus) decreased. Full article

(This article belongs to the Special Issue Effects of Climate and Environmental Change on Freshwater Ecosystems)

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9 pages, 342 KiB

Open AccessFeature PaperArticle

Continental vs. Global Niche-Based Modelling of Freshwater Species’ Distributions: How Big Are the Differences in the Estimated Climate Change Effects?

by Danijela Markovic, Jörg Freyhof and Oskar Kärcher

Water 2021, 13(6), 816; https://doi.org/10.3390/w13060816 - 16 Mar 2021

Viewed by 1757

Abstract

Thermal response curves that depict the probability of occurrence along a thermal gradient are used to derive various species’ thermal properties and abilities to cope with warming. However, different thermal responses can be expected for different portions of a species range. We focus [...] Read more.

Thermal response curves that depict the probability of occurrence along a thermal gradient are used to derive various species’ thermal properties and abilities to cope with warming. However, different thermal responses can be expected for different portions of a species range. We focus on differences in thermal response curves (TRCs) and thermal niche requirements for four freshwater fishes (Coregonus sardinella, Pungitius pungitius, Rutilus rutilus, Salvelinus alpinus) native to Europe at (1) the global and (2) European continental scale. European ranges captured only a portion of the global thermal range with major differences in the minimum (T_min), maximum (T_max) and average temperature (T_av) of the respective distributions. Further investigations of the model-derived preferred temperature (T_pref), warming tolerance (WT = T_max − T_pref), safety margin (SM = T_pref − T_av) and the future climatic impact showed substantially differing results. All considered thermal properties either were under- or overestimated at the European level. Our results highlight that, although continental analyses have an impressive spatial extent, they might deliver misleading estimates of species thermal niches and future climate change impacts, if they do not cover the full species ranges. Studies and management actions should therefore favor whole global range distribution data for analyzing species responses to environmental gradients. Full article

(This article belongs to the Special Issue Effects of Climate and Environmental Change on Freshwater Ecosystems)

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26 pages, 3305 KiB

Open AccessArticle

Role of the Hyporheic Zone in Increasing the Resilience of Mountain Streams Facing Intermittency

by Maria Cristina Bruno, Alberto Doretto, Fulvio Boano, Luca Ridolfi and Stefano Fenoglio

Water 2020, 12(7), 2034; https://doi.org/10.3390/w12072034 - 17 Jul 2020

Cited by 10 | Viewed by 2485

Abstract

We investigated the impact of intermittence in previously-perennial Alpine stream reaches, targeting the role of the hyporheic zone in increasing the resilience of these aquatic systems. We selected a perennial and an intermittent site in a reach of the Po River (North-Western Italy). [...] Read more.

We investigated the impact of intermittence in previously-perennial Alpine stream reaches, targeting the role of the hyporheic zone in increasing the resilience of these aquatic systems. We selected a perennial and an intermittent site in a reach of the Po River (North-Western Italy). We installed piezometers reaching −1 m (permanent and intermittent site), and −3 m (intermittent site) and monitored three supraseasonal droughts over a period of three years. We classified the hyporheic fauna into three categories of increasing affinity to life in the hyporheic (stygoxene, stygophile, stygobite), and used communities composition, abundance, beta-diversity and functional groups: (1) to compare assemblages at the same depth but with different hydrological characteristics, as well as assemblages from two depths at the intermittent site, and (2) to assess how the connection with surface water and the direction of the vertical aquifer flow determined the faunistic assemblages. Different taxonomic groups responded differently to intermittence, the hyporheic zone acted as a refuge increasing the resilience of the system, but resilience decreased with increasing degree of affinity to hyporheic life. Disentangling the effects of intermittence on the different faunistic component in the hyporheic zone can help guiding effective protection and restoration measures of river systems with temporary reaches. Full article

(This article belongs to the Special Issue Effects of Climate and Environmental Change on Freshwater Ecosystems)

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12 pages, 1199 KiB

Open AccessCommunication

Water–Air Interface Greenhouse Gas Emissions (CO₂, CH₄, and N₂O) Emissions Were Amplified by Continuous Dams in an Urban River in Qinghai–Tibet Plateau, China

by Dengxing Yang, Xufeng Mao, Xiaoyan Wei, Yaqing Tao, Zhifa Zhang and Jianhai Ma

Water 2020, 12(3), 759; https://doi.org/10.3390/w12030759 - 10 Mar 2020

Cited by 12 | Viewed by 3871

Abstract

Continuous dams may lead to great variation in greenhouse gas (GHG) emissions from rivers, which contribute more uncertainty to regional carbon balance. This study is among the first to determine water–air interface GHGs (CO₂, CH₄, and N₂O) [...] Read more.

Continuous dams may lead to great variation in greenhouse gas (GHG) emissions from rivers, which contribute more uncertainty to regional carbon balance. This study is among the first to determine water–air interface GHGs (CO₂, CH₄, and N₂O) in a river with continuous dams in plateau city. Combined static-chamber gas and meteorological chromatography were utilized to monitor the GHGs emission flux at the water–air interface within four continuous dams in the Huoshaogou River in the Qinghai–Tibet Plateau, China. A variation coefficient (VC) and amplification coefficient (AC) were designed to detect the influence of continuous dams on GHG emissions. Results indicate that (1) cascade dams presented an amplifying effect on GHGs emissions from the water-air interface. The VCs of three types of GHGs are 3.7–6.7 times higher than those of the undammed area. The ACs of three types of GHGs are 2.7–4.1 times larger than environmental factors; (2) the average GHG emission fluxes in some dams are higher than that of the first dam, indicating that an amplifying effect may have been accumulated by some continuous dams; (3) EC, pH, T_water, T_air and TDS are found to be principle influencing factors of GHG emission and light intensity, T_water, TOC (plant), TN (sediment) and TOC (sediment) are found to be associated with accumulative changes in GHG emission. Full article

(This article belongs to the Special Issue Effects of Climate and Environmental Change on Freshwater Ecosystems)

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18 pages, 4012 KiB

Open AccessArticle

Headwaters’ Isotopic Signature as a Tracer of Stream Origins and Climatic Anomalies: Evidence from the Italian Alps in Summer 2018

by Chiara Marchina, Valeria Lencioni, Francesca Paoli, Marzia Rizzo and Gianluca Bianchini

Water 2020, 12(2), 390; https://doi.org/10.3390/w12020390 - 01 Feb 2020

Cited by 15 | Viewed by 2985

Abstract

Glaciers are shrinking due to global warming, resulting in a diminishing contribution of ice and snowmelt to headwaters and subsequent consequences to freshwater ecosystems. Within this context, we tested whether water-stable isotopes are spatio-temporal tracers of (i) water in high altitude periglacial environments, [...] Read more.

Glaciers are shrinking due to global warming, resulting in a diminishing contribution of ice and snowmelt to headwaters and subsequent consequences to freshwater ecosystems. Within this context, we tested whether water-stable isotopes are spatio-temporal tracers of (i) water in high altitude periglacial environments, being the isotopic signature of surface water inherited from the snow/icemelt, groundwater, and rainfall; and (ii) regional (year-specific) meteorological conditions, being the isotopic signature of precipitations affected by air temperature, humidity and aqueous vapour origin, ascribing stable isotopes to the list of “essential climate variables″ (ECVs). To this end, we investigated the ionic and isotopic composition (δ¹⁸O and δ²H) of six high-altitude streams and one pond in the Italian Alps (Noce and Sarca basins) during the ablation season in 2018. Differences between habitat types (pond, kryal, rhithral, krenal) were detected. More negative values of δ¹⁸O and δ²H were recorded in the kryal and glacio-rhithral sites, dominated by ice and snowmelt, in early summer. Less negative values were recorded in these sites in late summer, as well as in the krenal sites, which were dominated by groundwater and rainfall inputs. The isotopic results also show that the complex alpine orography influences air masses and moisture, ultimately resulting in isotopic differences in the precipitations of neighboring but distinct catchments (Sarca and Noce basins). On average, less negative values were recorded in the Sarca basin, characterized by a higher contribution of precipitation of Mediterranean origin. In general, isotopic results of the entire water population appeared to be strongly influenced by the regional climatic anomaly of 2018, which was anomalously warm. Therefore, the study will provide additional information for the climate change debate, proposing water isotopes as ECVs for assessing change in a warmer future. Full article

(This article belongs to the Special Issue Effects of Climate and Environmental Change on Freshwater Ecosystems)

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16 pages, 3212 KiB

Open AccessArticle

Assessment of Anthropogenic Impact versus Climate Change on the Succession of the Diatom Community in Lugu Lake (Yunnan-Guizhou Plateau, China) Using the Sedimentary Record of Geochemical Elements

by Yi Liu, Chuanhong Chen and Shao Yang

Water 2019, 11(4), 655; https://doi.org/10.3390/w11040655 - 29 Mar 2019

Cited by 8 | Viewed by 3396

Abstract

The lake ecosystems on the Yunnan-Guizhou Plateau in China have degraded in recent decades under the effects of anthropogenic activities and climate change. The human impact on the oligotrophic Lugu Lake aquatic ecosystem was evaluated using the sediment records of metals, nitrogen isotopes [...] Read more.

The lake ecosystems on the Yunnan-Guizhou Plateau in China have degraded in recent decades under the effects of anthropogenic activities and climate change. The human impact on the oligotrophic Lugu Lake aquatic ecosystem was evaluated using the sediment records of metals, nitrogen isotopes (δ¹⁵N) and magnetic susceptibility over the past 200 years. Three periods were identified based on the trace metal and δ¹⁵N records. During the first stage (1816–1976 AD), the concentrations of metals, δ¹⁵N and magnetic susceptibility were low with small variations. The anthropogenic contributions to the inputs were also small, except for Ni, reflecting minor human activities in the watershed, and no significant change was observed in the sediment record of the diatom assemblage. During the second stage (1976–2001 AD), the concentrations of Zn and δ¹⁵N increased, as well as the anthropogenic contribution of Zn. However, no significant change was detected in the anthropogenic sources of the other metals. These results reflect the low-level use of chemical fertilizers. The major shift in the sediment diatom assemblage during this stage was mainly attributed to regional climate change. During the third stage (2001–2010 AD), the concentrations of the sedimentary metals (Ni, Cr, Mn, Cu, Hg and Al) increased rapidly, with the exception of As and Zn, and a similar increasing trend was observed in the changes by anthropogenic sources of Ni, Cr, Mn and Cu. RDA (Redundancy Analysis) and variance partitioning analysis showed that the human impact and climate proxies independently explained 31.59% and 4.26% of the change of diatom community, respectively, and the interaction between climate change and human impact accounted for 18.61% of the change of diatom community. Tourism-dominated human activities, which were reflected in the metals profiles, facilitated the dominance of eutrophic species and reduced that of oligotrophic species. The development of tourism was likely the main driving force for the succession of diatom assemblages in the third stage. In summary, the anthropogenic input of trace metals in Lugu Lake is still at a low level. However, the significant growth trend in metals over the past decade is significantly related to the change in the lake ecosystem. Therefore, the effects of human activities, especially tourism, on the watershed should be controlled for the protection of the oligotrophic Lugu Lake. Full article

(This article belongs to the Special Issue Effects of Climate and Environmental Change on Freshwater Ecosystems)

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