Anthropogenically forced changes in global freshwater biodiversity demand more efficient monitoring approaches. Consequently, environmental DNA (eDNA) analysis is enabling ecosystem-scale ...biodiversity assessment, yet the appropriate spatio-temporal resolution of robust biodiversity assessment remains ambiguous. Here, using intensive, spatio-temporal eDNA sampling across space (five rivers in Europe and North America, with an upper range of 20-35 km between samples), time (19 timepoints between 2017 and 2018) and environmental conditions (river flow, pH, conductivity, temperature and rainfall), we characterise the resolution at which information on diversity across the animal kingdom can be gathered from rivers using eDNA. In space, beta diversity was mainly dictated by turnover, on a scale of tens of kilometres, highlighting that diversity measures are not confounded by eDNA from upstream. Fish communities showed nested assemblages along some rivers, coinciding with habitat use. Across time, seasonal life history events, including salmon and eel migration, were detected. Finally, effects of environmental conditions were taxon-specific, reflecting habitat filtering of communities rather than effects on DNA molecules. We conclude that riverine eDNA metabarcoding can measure biodiversity at spatio-temporal scales relevant to species and community ecology, demonstrating its utility in delivering insights into river community ecology during a time of environmental change.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of recently formed
Salmo trutta
scale hydroxyapatite and otolith aragonite provided biogeochemical tags of S. trutta ...at six sites (>7.5 km apart) in a small upland catchment (drainage area: ~1800 km
2
). 87% and 89% of fish were correctly classified to their site of capture based on Sr, Mn, Ba, and Mg concentrations in scales and otoliths, respectively. Sr, Mn, and Ba were highly significantly correlated between structures of the same fish (P < 0.001). Ba and Mn in both structures were significantly correlated with stream water chemistries at each site (P < 0.05). Significant differences among sites were found in 11 element concentrations in scales and six element concentrations in otoliths (P < 0.05). Broadening the suite of elements improved the classification to 90% when using otoliths and 92% when using scales. Although there appears to be some degree of postdepositional change in scale hydroxyapatite in sea-run S. trutta, it was not sufficient to completely overprint the freshwater signature. Scales offer a nonlethal sampling alternative to otoliths and appear to provide a biogeochemical tag comparable in performance, but further work needs to examine the degree of postdepositional change in scale hydroxyapatite.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Natural variability in stable isotope ratios and element concentrations in calcified structures of fish (e.g. scales and otoliths) has provided biogeochemical ‘tags’ for studying origins and ...movements of marine species, but has been little used in freshwater studies. We examine whether variability in scale δ
15
N and δ
13
C values of
Salmo trutta
L., could provide a tag of fish over small spatial scales in a small river catchment (River Dee, U.K.) and compared their performance as tags with that of scale/otolith element concentrations. Whole scale δ
15
N and δ
13
C values differed among six study sites and fish could be classified to their site of origin with a high degree of accuracy. Classifying fish to their site of capture was marginally superior using scale δ
15
N and δ
13
C values compared to that achieved using Sr, Mn, Ba and Mg in scale hydroxyapatite or otolith aragonite. Scale δ
15
N and δ
13
C values could therefore provide non-lethally collectable biogeochemical tags superior in performance to element concentrations in otoliths and scales. A comprehensive study of δ
15
N and δ
13
C values within freshwater systems would develop our understanding of factors influencing geographical variability in baseline δ
15
N and δ
13
C signatures.
The Arctic charr (Salvelinus alpinus) is a species of cultural, economic and conservation importance, but hitherto, investigations of critical early life stages have been few. Here, at a lake in the ...United Kingdom, we used swim‐up traps to investigate the phenology of fry emergence and associations between fry density and habitat. The first emergence occurred on 4 or 5 March 2020 and 2021, with numbers peaking and remaining stable in the following 2 weeks. Emergence in 2021 had finished by 27 March but on the same date in 2020 emergence was ongoing when COVID‐19 ended sampling. Substrate particle size ranged 31–94 mm and was negatively correlated with fry density. Likewise, density was negatively correlated with water depth and aquatic plant cover, but there was no relationship with flow velocity. Traps were effective and non‐destructive for assessing the location and productivity of spawning sites for this locally threatened species.
Natural variability in stable isotope ratios and element concentrations in calcified structures of fish (e.g. scales and otoliths) has provided biogeochemical 'tags' for studying origins and ...movements of marine species, but has been little used in freshwater studies. We examine whether variability in scale δ^sup 15^N and δ^sup 13^C values of Salmo trutta L., could provide a tag of fish over small spatial scales in a small river catchment (River Dee, U.K.) and compared their performance as tags with that of scale/otolith element concentrations. Whole scale δ^sup 15^N and δ^sup 13^C values differed among six study sites and fish could be classified to their site of origin with a high degree of accuracy. Classifying fish to their site of capture was marginally superior using scale δ^sup 15^N and δ^sup 13^C values compared to that achieved using Sr, Mn, Ba and Mg in scale hydroxyapatite or otolith aragonite. Scale δ^sup 15^N and δ^sup 13^C values could therefore provide non-lethally collectable biogeochemical tags superior in performance to element concentrations in otoliths and scales. A comprehensive study of δ^sup 15^N and δ^sup 13^C values within freshwater systems would develop our understanding of factors influencing geographical variability in baseline δ^sup 15^N and δ^sup 13^C signatures.PUBLICATION ABSTRACT
Natural variability in stable isotope ratios and element concentrations in calcified structures of fish (e.g. scales and otoliths) has provided biogeochemical 'tags' for studying origins and ...movements of marine species, but has been little used in freshwater studies. We examine whether variability in scale delta super(15)N and delta super(13)C values of Salmo trutta L., could provide a tag of fish over small spatial scales in a small river catchment (River Dee, U.K.) and compared their performance as tags with that of scale/otolith element concentrations. Whole scale delta super(15)N and delta super(13)C values differed among six study sites and fish could be classified to their site of origin with a high degree of accuracy. Classifying fish to their site of capture was marginally superior using scale delta super(15)N and delta super(13)C values compared to that achieved using Sr, Mn, Ba and Mg in scale hydroxyapatite or otolith aragonite. Scale delta super(15)N and delta super(13)C values could therefore provide non-lethally collectable biogeochemical tags superior in performance to element concentrations in otoliths and scales. A comprehensive study of delta super(15)N and delta super(13)C values within freshwater systems would develop our understanding of factors influencing geographical variability in baseline delta super(15)N and delta super(13)C signatures.
An inevitable consequence of the development of the Atlantic salmon, Salmo salar L., farming industry in coastal waters of the British Isles has been the loss of farmed salmon to the wild, their ...occurrence in inshore waters and rivers, and their appearance in coastal and freshwater fisheries. Monitoring programmes have been developed throughout the British Isles, variously using scientific sampling, catch records from coastal or freshwater fisheries or both, and scientific sampling of catches from in-river traps. We compare the results of these monitoring programmes with regional production and the numbers of escapees reported from marine fish farms. We also consider the effectiveness of the programmes for assessing the prevalence of farmed salmon that escape from marine cages. Finally, we make recommendations for improvements to these programmes and for the development of best practice, including the scientific sampling of in-river spawning stocks through fishery-independent sources, identification of fish origin based on at least two methods, assessment of the degree of incorrect classification, and the timely and accurate reporting of all escapes.
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