Microplastics in brown trout (Salmo trutta Linnaeus, 1758) from an Irish riverine system

Rivers play an important role in the overall transport of microplastic pollution (1 μm to 5 mm), with fluvial dynamics expected to influence biotic interactions, particularly for fish. So far, there have been few assessments of microplastics in freshwater salmonids. The prevalence (i.e. percentage occurrence) and burden (i.e. abundance per fish) of microplastics were assessed in the gastrointestinal tracts (GITs) and stomach contents (SCs) of 58 brown trout Salmo trutta Linnaeus, 1758 sampled at six sites along the River Slaney catchment in south-east Ireland. Sites were divided into two classifications (high and low exposure) based on proximity to microplastic pollution sources, comprising three sites each. Analysis of biological traits (e.g. fish length) and diet was performed on the same fish to determine possible factors explaining microplastic burden. Microplastics were found in 72% of fish having been recovered from 66% of GITs (1.88 ± 1.53 MPs fish⁻1) and 28% of SCs (1.31 ± 0.48 MPs fish⁻1). Fibres were the dominant particle type recovered from GITs (67%) and SCs (57%) followed by fragments. No difference in median microplastic burden was observed between fish collected in high and low exposure sites. Microplastic burden was unrelated to fish fork length, while microplastic size distribution (100 ≤ 350 μm, 350 μm to ≤ 5 mm) was unrelated to S. trutta age class estimates. Furthermore, microplastic burden was not explained by dietary intake. Though further research is necessary, this study showed the presence of microplastics in wild S. trutta collected from an Irish riverine system, which could have further implications for top-level consumers that feed on the species, including humans. Further analysis is required to determine possible trophic linkages for the species, with respect to microplastics, and to assess the suitability of S. trutta for monitoring microplastics in river systems.ye

Sunlight-Exposed Biofilm Microbial Communities Are Naturally Resistant to Chernobyl Ionizing-Radiation Levels

BACKGROUND: The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. METHODOLOGY/PRINCIPAL FINDINGS: To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. CONCLUSIONS/SIGNIFICANCE: Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general diversity patterns, despite increased mutation levels at the single-OTU level. Therefore, biofilm communities growing in sunlight exposed substrates are capable of coping with increased mutation rates and appear pre-adapted to levels of ionizing radiation in Chernobyl due to their natural adaptation to periodical desiccation and ambient UV radiation

Microplastics in brown trout Salmo trutta Linnaeus, 1758 from an Irish riverine system

Rivers play an important role in the overall transport of microplastic pollution (1 μm to 5 mm), with fluvial dynamics expected to influence biotic interactions, particularly for fish. So far, there have been few assessments of microplastics in freshwater salmonids. The prevalence (i.e. percentage occurrence) and burden (i.e. abundance per fish) of microplastics were assessed in the gastrointestinal tracts (GITs) and stomach contents (SCs) of 58 brown trout Salmo trutta Linnaeus, 1758 sampled at six sites along the River Slaney catchment in south-east Ireland. Sites were divided into two classifications (high and low exposure) based on proximity to microplastic pollution sources, comprising three sites each. Analysis of biological traits (e.g. fish length) and diet was performed on the same fish to determine possible factors explaining microplastic burden. Microplastics were found in 72% of fish having been recovered from 66% of GITs (1.88 ± 1.53 MPs fish⁻1) and 28% of SCs (1.31 ± 0.48 MPs fish⁻1). Fibres were the dominant particle type recovered from GITs (67%) and SCs (57%) followed by fragments. No difference in median microplastic burden was observed between fish collected in high and low exposure sites. Microplastic burden was unrelated to fish fork length, while microplastic size distribution (100 ≤ 350 μm, 350 μm to ≤ 5 mm) was unrelated to S. trutta age class estimates. Furthermore, microplastic burden was not explained by dietary intake. Though further research is necessary, this study showed the presence of microplastics in wild S. trutta collected from an Irish riverine system, which could have further implications for top-level consumers that feed on the species, including humans. Further analysis is required to determine possible trophic linkages for the species, with respect to microplastics, and to assess the suitability of S. trutta for monitoring microplastics in river systems

Session C7: 'Dodgy' Barriers: Conservation Implications and Mitigation Outcomes for Sea Lamprey in Irish SACs

Presenting Author Bio: Lead scientist on Inland Fisheries Ireland’s (IFI) investigations on Annex II Habitats Directive fish species (lamprey, shad and whitefish (pollan)) and Red Data Book Fish (char and smelt). Leads strategies in IFI to examine connectivity and anadromous fish; to improve hydromorphology (under WFD) in arterially-drained rivers; oversees works and monitors impacts of strategies on fish community and on riparian zone.Abstract: Anthropogenic structures in rivers can impede fish passage. In Ireland, weirs were commonly installed on major and minor rivers to harness water power to operate machinery. Many such structures are now derelict. Many had fish passage facilities installed, the target species being Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.). A combination of Water Framework Directive and Habitats Directive provides a lens to critically examine anthropogenic barriers and their possible impacts on fish species of conservation significance, particularly in channels designated as Special Area of Conservation (SAC) for anadromous species. In Ireland, these species include sea lamprey (Petromyzon marinus L.), Twaite shad (Alosa fallax Lacepede) and Atlantic salmon. Surveys have identified substantial clustering of sea lamprey nesting sites below the most downstream major weirs on the Irish SACs and limited upstream penetration, as recorded in catchment-wide larval sea lamprey distribution. Ireland has a conservation management objective of achieving unimpeded access to 75% of the main stem channel length for spawning anadromous lamprey migration. The potential for achieving this target was examined in two SAC rivers – the Mulkear (Lower River Shannon SAC) and the Munster Blackwater SAC. Barrier passability or porosity was examined using the SNIFFER barrier tool and information on the status of sea lamprey was generated from spawning site surveys and from catchmentwide electric fishing surveys of larval lamprey. Implementation of barrier management strategies was associated with substantial increase in numbers and degree of dispersal of Petromyzon redds on the Mulkear. The two major Blackwater weirs are scheduled for modification and scope for enhanced dispersal of migrating adult sea lamprey is examined in the context of the design of proposed modification and of available sea lamprey larval records in the Blackwater catchment

Session C7: \u27Dodgy\u27 Barriers: Conservation Implications and Mitigation Outcomes for Sea Lamprey in Irish SACs

Abstract: Anthropogenic structures in rivers can impede fish passage. In Ireland, weirs were commonly installed on major and minor rivers to harness water power to operate machinery. Many such structures are now derelict. Many had fish passage facilities installed, the target species being Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.). A combination of Water Framework Directive and Habitats Directive provides a lens to critically examine anthropogenic barriers and their possible impacts on fish species of conservation significance, particularly in channels designated as Special Area of Conservation (SAC) for anadromous species. In Ireland, these species include sea lamprey (Petromyzon marinus L.), Twaite shad (Alosa fallax Lacepede) and Atlantic salmon. Surveys have identified substantial clustering of sea lamprey nesting sites below the most downstream major weirs on the Irish SACs and limited upstream penetration, as recorded in catchment-wide larval sea lamprey distribution. Ireland has a conservation management objective of achieving unimpeded access to 75% of the main stem channel length for spawning anadromous lamprey migration. The potential for achieving this target was examined in two SAC rivers – the Mulkear (Lower River Shannon SAC) and the Munster Blackwater SAC. Barrier passability or porosity was examined using the SNIFFER barrier tool and information on the status of sea lamprey was generated from spawning site surveys and from catchmentwide electric fishing surveys of larval lamprey. Implementation of barrier management strategies was associated with substantial increase in numbers and degree of dispersal of Petromyzon redds on the Mulkear. The two major Blackwater weirs are scheduled for modification and scope for enhanced dispersal of migrating adult sea lamprey is examined in the context of the design of proposed modification and of available sea lamprey larval records in the Blackwater catchment