Trawling through time: reconstructing a late nineteenth century beam trawl for scientific inshore fishery investigations

\ua9 Crown 2024.Understanding long-term change in fish populations often relies on comparing catches from historical and contemporary trawl surveys. However, such comparisons may not resolve biases associated with differences in fishing gears and their relative catchabilities. It is possible to reduce these uncertainties by replicating historical trawl gear and practices. With the availability of unique historical catch data, we investigated the trawl gear employed by the Northumberland Sea Fisheries Committee (NSFC) during scientific surveys conducted between 1892–1913 in inshore waters of the Northumberland coast (UK), and describe our attempt to reconstruct the gear using currently available materials. We reviewed the historical literature, photographs and acquired technical expertise to reconstruct a late nineteenth century beam trawl used by the NSFC. The replica gear consisted of a 6.7 m beam connected by two Brixham style wrought-iron trawl heads, which held open a triangular-shaped trawl net with rounded ground-rope. Following construction, we tested the performance and catchability of the replica gear by conducting comparative trawls using a modern otter trawl in August 2018 and March 2019. Both trawl gears exhibited similar catches for flatfish in August trials, yet a higher proportion of individuals were landed by the otter trawl in March. Zero or negligible catches were exhibited by the replica gear during this period. This work collates relevant information to describe the evolution, design and functioning of late nineteenth century beam trawls used around the British Isles, providing an important repository for investigators interested in trawl technology and survey designs

Is the meiofauna a good indicator for climate change and anthropogenic impacts?

Our planet is changing, and one of the most pressing challenges facing the scientific community revolves around understanding how ecological communities respond to global changes. From coastal to deep-sea ecosystems, ecologists are exploring new areas of research to find model organisms that help predict the future of life on our planet. Among the different categories of organisms, meiofauna offer several advantages for the study of marine benthic ecosystems. This paper reviews the advances in the study of meiofauna with regard to climate change and anthropogenic impacts. Four taxonomic groups are valuable for predicting global changes: foraminifers (especially calcareous forms), nematodes, copepods and ostracods. Environmental variables are fundamental in the interpretation of meiofaunal patterns and multistressor experiments are more informative than single stressor ones, revealing complex ecological and biological interactions. Global change has a general negative effect on meiofauna, with important consequences on benthic food webs. However, some meiofaunal species can be favoured by the extreme conditions induced by global change, as they can exhibit remarkable physiological adaptations. This review highlights the need to incorporate studies on taxonomy, genetics and function of meiofaunal taxa into global change impact research

Species-Specific Traits Rather Than Resource Partitioning Mediate Diversity Effects on Resource Use

Background: The link between biodiversity and ecosystem processes has firmly been established, but the mechanisms underpinning this relationship are poorly documented. Most studies have focused on terrestrial plant systems where resource use can be difficult to quantify as species rely on a limited number of common resources. Investigating resource use at the bulk level may not always be of sufficient resolution to detect subtle differences in resource use, as species-specific nutritional niches at the biochemical level may also moderate diversity effects on resource use. Methodology/Principal Findings: Here we use three co-occurring marine benthic echinoderms (Brissopsis lyrifera, Mesothuria intestinalis, Parastichopus tremulus) that feed on the same phytodetrital food source, to determine whether resource partitioning is the principal mechanism underpinning diversity effects on resource use. Specifically we investigate the use of phytodetrital pigments ( chlorophylls and carotenoids) because many of these are essential for biological functions, including reproduction. Pigments were identified and quantified using reverse-phase high performance liquid Chromatography ( HPLC) and data were analysed using a combination of extended linear regression with generalised least squares (GLS) estimation and standard multivariate techniques. Our analyses reveal no species-specific selectivity for particular algal pigments, confirming that these three species do not partition food resources at the biochemical level. Nevertheless, we demonstrate increased total resource use in diverse treatments as a result of selection effects and the dominance of one species (B. lyrifera). Conclusion: Overall, we found no evidence for resource partitioning at the biochemical level, as pigment composition was similar between individuals, which is likely due to plentiful food availability. Reduced intra-specific competition in the species mixture combined with greater adsorption efficiency and differences in feeding behaviour likely explain the dominant use of resources by B. lyrifera