DOI: 10.5285/725f789f-19d0-4a6f-832c-4f542c966452
title: Images of histological sections of oocytes for the bivalve Astarte crenata and seastar Ctenodiscus crispatus from the Western Barents Sea for summer 2017.

description: Images of histological sections of oocytes to quantify oocyte size frequency distributions in Astarte crenata and Ctenodiscus crispatus used in the analyses by Reed et al. 2021 (Ecology and Evolution) from the Western Barents Sea during summer 2017 across a North - South transect intersecting the polar front. Supported by The Changing Arctic Ocean Seafloor (ChAOS) - how changing sea ice conditions impact biological communities, biogeochemical processes and ecosystems project (NE/N015894/1 and NE/P006426/1, 2017-2021), Natural Environment Research Council (NERC) in the UK.
description: Specimens of A. crenata and C. crispatus were collected in July 2017 (JR16006, RRS James Clark Ross; Hopkins 2018) using a 1.25 m Agassiz trawl (AGT) towed for 15 minutes at a ship speed of 1 knot, at three stations along the 30°E meridian across the approximate location of the Polar Front (B13, 74° 49 N (South of the polar front); B14, 76° 50 N (approximate location of the polar front); B16, 80° 06 N (North of the polar front)). Four trawls were conducted at each station to ensure sufficient spatial replication. Ctenodiscus crispatus were found at all stations, whereas A. crenata were only found at stations B13 and B16. Fauna were sieved over a 1 cm mesh, retained and fixed in 10% phosphate buffered formalin (4% formaldehyde) prior to morphological and histological examination. Images of oocytes: Images of stained slides of histological sections from individual females were captured using a Nikon D5000 digital SLR camera mounted on an Olympus (BH-2) stereomicroscope and analysed using ImageJ v 1.48. Slides were photographed at X10 magnification. Replicate photographs were taken to ensure 100 unique oocytes were measured for each female. Composite images were generated for easy analysis wherever possible. Full descriptions and additional information provided in Reed et al. 2021 Ecology and Evolution in main manuscript and supplementary information. Folder names: cruisenumber_species_site Sub-folder names: cruisenumber_species_site_spcode N.B. For species, Ast represents Astarte crenata and Ctdi represents Ctenodiscus crispatus. Site = sampling site. spcode = specimen code = individual number/ identifier. Each folder contains a number of subfolders representing the slide number from which the contained images are taken N.B. For individuals where fewer images were taken, multiple subfolders identifying 'slide number' were not required. These images are archived individually in the main specimen code folder. A small 'c' represents images that were taken as a composite image of an entire histology section (and therefore will overlap). However, owed to the fact that it was not always possible to render a completed composite image accurately, a complete composite image is not available in every folder labelled 'c'.
description: Instrumentation: Rotary microtome Nikon D5000 digital SLR camera Olympus BHS (BH-2) stereomicroscope
description: Standard protocols were followed, and data entry double checked by an independent person.