Variability in the duration and timing of the estuarine to freshwater transition of critically endangered European eel Anguilla anguilla

380 18 1975 3 6901 document 1975 SI_variability.csv text/plain 325ca34c82d43200de8a623bc4ed04d6 MD5 46972 2024-05-20 15:41:27 https://bordar.bournemouth.ac.uk/380/1/SI_variability.csv 380 1 1 text/plain text en public cc_by_nd_4

SI_variability.csv

data 1976 3 6903 document 1976 README_RMB_Variability.docx application/vnd.openxmlformats-officedocument.wordprocessingml.document 91b388441d4a08d70e243ac58aa7bacd MD5 16739 2024-05-20 15:48:30 https://bordar.bournemouth.ac.uk/380/2/README_RMB_Variability.docx 380 2 2 application/vnd.openxmlformats-officedocument.wordprocessingml.document text en public cc_by_nd_4

README_RMB_Variability.docx

readme 1977 1 6911 document 1977 indexcodes.txt text/plain 365c2e390761abbc26dd343d05b3cdae MD5 961 2024-05-20 16:01:33 https://bordar.bournemouth.ac.uk/380/3/indexcodes.txt 380 3 3 text/plain other Generate index codes conversion from text to indexcodes en public

indexcodes.txt

http://eprints.org/relation/isVersionOf https://bordar.bournemouth.ac.uk/id/document/1976 http://eprints.org/relation/isVolatileVersionOf https://bordar.bournemouth.ac.uk/id/document/1976 http://eprints.org/relation/isIndexCodesVersionOf https://bordar.bournemouth.ac.uk/id/document/1976 archive 6877 disk0/00/00/03/80 2024-06-18 08:08:59 2024-06-18 08:09:15 2024-06-18 08:08:59 data_collection show Boardman Rose boardmanr@bournemouth.ac.uk Pinder Adrian apinder@bournemouth.ac.uk Piper Adam adam.piper@ioz.ac.uk Gutmann Roberts Catherine catherine.gutmannroberts@plymouth.ac.uk Wright Ros ros.wright@environment-agency.gov.uk Britton Robert rbritton@bournemouth.ac.uk Variability in the duration and timing of the estuarine to freshwater transition of critically endangered European eel Anguilla anguilla - Dataset pub facsci Anguillid; Stable isotope analysis; Critically endangered; Glass eel; Elver; Freshwater;Estuary The European eel (Anguilla anguilla L.) is a critically endangered catadromous fish. Their inshore and in-river arrival as glass eel and elvers is an important stage of their life cycle, marking the transition from marine to freshwater habitats. Considerable knowledge gaps remain on the temporal and spatial patterns of this transition period to freshwater residency. Stable isotope (SI) analysis (δ13C, δ15N) was used to assess the timing and duration of the marine to freshwater transition among glass eels and elvers migrating upstream of the weirs at, or just upstream of, the tidal limit of four English rivers. (Parrett, Frome, Piddle, Chelmer). Variability in SI was low in the Parrett and Frome, resulting in narrow isotopic niches, but was high in the Piddle and Chelmer, resulting in wider niches. The Parrett and Frome data were then used to train a discriminant function analysis (DFA) model to classify eels as ‘marine’, ‘freshwater-established’ and ‘transitioning’. When applied to the Piddle and Chelmer eel SI data, only a small proportion of eels were classified as marine and transitioning, with most being freshwater established. These results suggest that most eels present in the lower reaches rivers have been present for sufficient time for their SI values to represent feeding on local prey resources, with relatively few eels being newly arrived from the marine environment. The transition of eels from marine to freshwater in this species can therefore be prolonged, with many ascending rivers at least one winter after their initial arrival. 2024-06-18 published Bournemouth University 10.18746/bmth.data.00000380 Other bordar@bournemouth.ac.uk Boardman Rose boardmanr@bournemouth.ac.uk Variability in the duration and timing of the estuarine to freshwater transition of critically endangered European eel Anguilla anguilla pub 10.1007/s00027-023-01033-y DOI https://link.springer.com/article/10.1007/s00027-023-01033-y pub Aquatic Sciences Bournemouth University Environment Agency Data was collected from four rivers in eastern, southern, and southwest England. Eels were captured monthly from May to September 2021 in the River Frome using back-mounted electric fishing (LR-24, Smith-Root, Vancouver, WA, USA). In the River Piddle, eels were captured weekly with a trap operated over 24-hour periods on an existing elver pass. Monthly monitoring traps installed over 24-hour periods were used to capture eels in the River Parrett from March to June in 2021 and 2022. Similarly, in the River Chelmer, eels were captured once a month between March and September in 2021 and 2022 using monitoring traps over 24-hour periods. The study was completed following the gaining of all relevant ethical and legislative approvals (UK Home Office Project Licence P47216841; Environment Agency permit reference EP/EW027-C-042/19919/01. 2021 2022