Novel insights into the marine phase and river fidelity of anadromous twaite shad Alosa fallax in the UK and Ireland

© 2020 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd Most research on anadromous fishes has been invested in their freshwater life-phases, resulting in a relatively sparse understanding of their spatial ecology during marine life-phases. However, understanding the marine dispersal of anadromous fishes is essential to identify threats and to implement conservation measures that fully encompass their lifecycle. The twaite shad Alosa fallax is an anadromous fish increasingly imperilled across its range due to pollution, harvesting, and impediments to freshwater migration, but little is known about its distribution and movements during its marine life-phase. Here, the application of acoustic telemetry provided novel insights into the coastal dispersal of twaite shad in the UK and Ireland during 2018–2019, and the freshwater entry of individuals during the 2019 spawning season. Of 73 twaite shad acoustic-tagged during their upstream migration in the River Severn in May 2018, 58 emigrated from the river. Twelve were subsequently detected 200 km to the south-west at the Taw–Torridge Estuary between July 2018 and April 2019, where estuarine movements up to 5.8 km inland occurred in summer, winter, and spring. One was subsequently detected in the Munster Blackwater Estuary (Ireland) and then in the River Severn, indicating a minimum movement distance of 950 km. Thirty-four (59%) of the emigrating individuals from 2018 re-entered fresh water in the rivers Severn (n = 33) and Wye (n = 2) in April and May 2019. These results suggest year-round use of estuarine and nearshore habitats by at least a subset of the twaite shad population during their marine phase, providing evidence of potential range overlap between populations that spawn in different areas in the UK and Ireland, which may be facilitated by substantial dispersal. The results also highlight the potential of telemetry for estimating freshwater and marine mortality, and the benefits of sharing detection data across networks

Drawing lines at the sand: evidence for functional vs. visual reef boundaries in temperate Marine Protected Areas.

Marine Protected Areas (MPAs) can either protect all seabed habitats within them or discrete features. If discrete features within the MPA are to be protected humans have to know where the boundaries are. In Lyme Bay, SW England a MPA excluded towed demersal fishing gear from 206 km(2) to protect rocky reef habitats and the associated species. The site comprised a mosaic of sedimentary and reef habitats and so 'non reef' habitat also benefited from the MPA. Following 3 years protection, video data showed that sessile Reef Associated Species (RAS) had colonised sedimentary habitat indicating that 'reef' was present. This suggested that the functional extent of the reef was potentially greater than its visual boundary. Feature based MPA management may not adequately protect targeted features, whereas site based management allows for shifting baselines and will be more effective at delivering ecosystem goods and services

Strandings of NE Atlantic gorgonians

Publisher policy: author can archive post-print on open access repository after an embargo period of 18 months. Publisher's version/PDF cannot be used. Must link to publisher version with DOI. Author's post-print must be released with a Creative Commons Attribution Non-Commercial No Derivatives License. publisher: Elsevier articletitle: Strandings of NE Atlantic gorgonians journaltitle: Biological Conservation articlelink: http://dx.doi.org/10.1016/j.biocon.2017.03.020 content_type: article copyright: © 2017 Elsevier Ltd. All rights reserved

The earliest ostracods: The geological evidence

The oldest assumed ostracods appear in the fossil record from the Tremadocian Paltodus deltifer conodont Biozone. Although geographically widespread these early ostracods have no obvious Cambrian antecedents. Their first appearance at ca. 485 Ma contrasts with molecular evidence that suggests a much earlier (latest Proterozoic or Cambrian) origin for ostracods. Some Cambrian bivalved arthropods such as Altajanella and Vojbokalina, conventionally referred to the Bradoriida, have carapace morphologies that resemble Ordovician palaeocopid ostracods, though such a relationship is unproven without soft part anatomy. Evidence from preserved soft anatomy demonstrates that Bradoriida, such as Kunmingella, and Phosphatocopida, essentially the Cambrian 'ostracod' record of traditional usage, belong outside the Eucrustacea. Early Ordovician ostracods appeared first in shallow marine, oxygenated environments on shelf margins, in a similar setting to other elements of the 'Paleozoic fauna'. Their biodiversity was low (3 named genera and ca. 12 species), though some taxa such as Nanopsis and Eopilla achieved widespread dispersal between major Ordovician palaeocontinents. As bradoriids were largely extinct by the Late Cambrian, ostracods do not appear to have directly competed with them for shallow marine environments. The rapid colonisation of these settings by ostracods may have been facilitated by the available ecospace vacated by Bradoriida