It is globally recognized that freshwater anglers can have a decisive role in promoting fish introductions. The aim of this study was to analyze freshwater anglers’ actions and perceptions regarding ...fish introductions, comparing two distinct situations, one with recently arrived non-natives fishes and another with older fish introductions, using the Iberian Peninsula as a case study. To achieve this goal, a bilingual survey was implemented on-line in Portugal and Spain and in person (direct inquiries) in two Iberian regions: Lower Ebro (older fish introductions) in Spain; and Lower Tagus (recent fish introductions) in Portugal. Results showed spatial differences in perceptions and actions, namely about the target species, awareness of the impact of non-native fishes, fish introductions reported and proportion of anglers that wanted new fish species. In the Ebro river there is a high percentage of foreign anglers, higher awareness of fish introduction impact and lower introduction rates reported than in the Tagus river. However, popularity of non-native species like European catfish, was higher in the Ebro. In general, although risk behaviors such as use of fish as life bait was of low prevalence for both countries (approx. 5%), it corresponds to large numbers of fish being introduced. Our conservative estimates revealed 273,600 events of bait discharge per year. Regarding the intentional introductions, we estimated a total of 140,000 intentional introduction (illegal) events per year. These findings may help to improve monitoring, awareness and fisheries management programs led by governmental agencies.
Graphical abstract
Functional diversity metrics have been suggested as important indicators of ecosystem functioning. We investigated the effects of land use mediated by local environmental variables on the fish ...assemblages’ functional structure in 18 headwater streams distributed in the Upper Paraná and Iguaçu ecoregions. The species were characterized according to habitat use, food resource use, life history, and hypoxia tolerance. We calculated functional diversity indices richness (FRic), evenness (FEve), divergence (FDiv), dispersion (FDis), diversity (RaoQ) and functional rarity indices distinctiveness (Disti), uniqueness (Uni), and evaluated the effects of regional and local variables on these indices using generalized linear models. The results highlighted the occurrence of the most functionally distinct and unique species in the forested streams. Moreover, we observed higher FRic in streams sampled in argisol, with a high ammonia load and low habitat diversity. Forested and agricultural covers positively affected FDis and RaoQ. Urban cover had a negative effect on FDis and RaoQ, mainly due to the increase in generalist functional groups in urban streams. Our findings emphasize the importance of forested cover in maintaining specialized species in fish assemblages of streams and preserving functional diversity and ecosystem functioning. Furthermore, these results contribute to direct conservation and recovery measures in freshwater environments.
Intensification of the use of natural resources is a world-wide trend driven by the increasing demand for water, food, fibre, minerals and energy. These demands are the result of a rising world ...population, increasing wealth and greater global focus on economic growth. Land use intensification, together with climate change, is also driving intensification of the global hydrological cycle. Both processes will have major socio-economic and ecological implications for global water availability. In this paper we focus on the implications of land use intensification for the conservation and management of freshwater ecosystems using Australia as an example. We consider this in the light of intensification of the hydrologic cycle due to climate change, and associated hydrological scenarios that include the occurrence of more intense hydrological events (extreme storms, larger floods and longer droughts). We highlight the importance of managing water quality, the value of providing environmental flows within a watershed framework and the critical role that innovative science and adaptive management must play in developing proactive and robust responses to intensification. We also suggest research priorities to support improved systemic governance, including adaptation planning and management to maximise freshwater biodiversity outcomes while supporting the socio-economic objectives driving land use intensification. Further research priorities include: i) determining the relative contributions of surface water and groundwater in supporting freshwater ecosystems; ii) identifying and protecting freshwater biodiversity hotspots and refugia; iii) improving our capacity to model hydro-ecological relationships and predict ecological outcomes from land use intensification and climate change; iv) developing an understanding of long term ecosystem behaviour; and v) exploring systemic approaches to enhancing governance systems, including planning and management systems affecting freshwater outcomes. A major policy challenge will be the integration of land and water management, which increasingly are being considered within different policy frameworks.
•This paper considers the impacts of land use and hydrological intensification on inland waters•Global issues are considered through the lens of Australian examples•Likely scenarios include wet regions becoming wetter, dry regions drier and storms more intense•The legacies of past land use change will need to be addressed•Proactive governance based on innovative science and adaptive management will be critical
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•We quantified pelagic microplastic pollution in Lake Hovsgol, Mongolia.•Lake Hovsgol is more polluted with microplastics than Lakes Huron and Superior.•Microplastics came from ...consumer goods; no microbeads/few pellets were observed.•Microplastics were sourced from population centers and distributed by the winds.•Without waste management, even small populations can heavily pollute large lakes.
Despite the large and growing literature on microplastics in the ocean, little information exists on microplastics in freshwater systems. This study is the first to evaluate the abundance, distribution, and composition of pelagic microplastic pollution in a large, remote, mountain lake. We quantified pelagic microplastics and shoreline anthropogenic debris in Lake Hovsgol, Mongolia. With an average microplastic density of 20,264 particles km−2, Lake Hovsgol is more heavily polluted with microplastics than the more developed Lakes Huron and Superior in the Laurentian Great Lakes. Fragments and films were the most abundant microplastic types; no plastic microbeads and few pellets were observed. Household plastics dominated the shoreline debris and were comprised largely of plastic bottles, fishing gear, and bags. Microplastic density decreased with distance from the southwestern shore, the most populated and accessible section of the park, and was distributed by the prevailing winds. These results demonstrate that without proper waste management, low-density populations can heavily pollute freshwater systems with consumer plastics.
Inland waters (lakes, reservoirs, streams, and rivers) are often substantial methane (CH₄) sources in the terrestrial landscape. They are, however, not yet well integrated in global greenhouse gas ...(GHG) budgets. Data from 474 freshwater ecosystems and the most recent global water area estimates indicate that freshwaters emit at least 103 teragrams of CH₄ year⁻¹, corresponding to 0.65 petagrams of C as carbon dioxide (CO₂) equivalents year⁻¹, offsetting 25% of the estimated land carbon sink. Thus, the continental GHG sink may be considerably overestimated, and freshwaters need to be recognized as important in the global carbon cycle.
► We assessed impacts of climate change on low flows and river temperatures globally. ► The largest predicted water temperature rises are for the US, Europe and China. ► Water temperature rises are ...exacerbated by decreasing summer low flows in most regions.
Climate change will affect hydrologic and thermal regimes of rivers, having a direct impact on freshwater ecosystems and human water use. Here we assess the impact of climate change on global river flows and river water temperatures, and identify regions that might become more critical for freshwater ecosystems and water use sectors. We used a global physically based hydrological-water temperature modelling framework forced with an ensemble of bias-corrected general circulation model (GCM) output for both the SRES A2 and B1 emissions scenario. This resulted in global projections of daily river discharge and water temperature under future climate. Our results show an increase in the seasonality of river discharge (both increase in high flow and decrease in low flow) for about one-third of the global land surface area for 2071–2100 relative to 1971–2000. Global mean and high (95th percentile) river water temperatures are projected to increase on average by 0.8–1.6 (1.0–2.2)°C for the SRES B1–A2 scenario for 2071–2100 relative to 1971–2000. The largest water temperature increases are projected for the United States, Europe, eastern China, and parts of southern Africa and Australia. In these regions, the sensitivities are exacerbated by projected decreases in low flows (resulting in a reduced thermal capacity). For strongly seasonal rivers with highest water temperatures during the low flow period, up to 26% of the increases in high (95th percentile) water temperature can be attributed indirectly to low flow changes, and the largest fraction is attributable directly to increased atmospheric energy input. A combination of large increases in river temperature and decreases in low flows are projected for the southeastern United States, Europe, eastern China, southern Africa and southern Australia. These regions could potentially be affected by increased deterioration of water quality and freshwater habitats, and reduced water available for human uses such as thermoelectric power and drinking water production.
The diversity and distribution of freshwater rotifers have been under-explored in China, especially from high altitude regions. We used molecular data to explore these points in the monogonont ...rotifer
Brachionus calyciflorus
species complex across China, covering both the low- and high-altitude regions. Populations of this species complex were detected in 44 of the 251 waterbodies sampled across China. Analysis of partial sequences of the nuclear ribosomal internal transcribed spacer (ITS-1) placed these populations in four distinct species (
B. dorcas
,
B. elevatus
,
B. calyciflorus
sensu stricto (
s.s.
) and
B. fernandoi
), and phylogenies based on sequences from a portion of the mitochondrial cytochrome
c
oxidase subunit I gene recognized seven groups within the
B. calyciflorus
species complex in China. The four species were congruent with the four morphogroups that we identified. All four species were present in the Eastern Plain and
B. dorcas
occurred nowhere else.
Brachionus elevatus
and
B. calyciflorus s.s.
were the only species present in the Northeast Plain and in the Yunnan-Guizhou Plateau, respectively. Cases of mito-nuclear discordance were detected in our specimens, suggesting occasional hybridization between different species of the
B. calyciflorus
species complex. Our results revealed the phylogeography and gene introgression in this species complex across China.
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