DOI: 10.5281/zenodo.14167122
title: Jensen, Meffre et al. 2024 - Gelatinous macrozooplankton in the North Sea: Biodiversity and distribution pattern during winter 2023-Q1 - raw dataset

description: Dataset for Data in Brief publication Jensen, Meffre, Werner, Huwer, Neumann, Jaspers (submitted)

The biodiversity and distribution of gelatinous macrozooplankton in the North Sea and adjacent waters during winter (January/February) 2023 is presented both quantitatively and qualitatively. The data include species-specific jellyfish and comb jelly community data, encountered during the North Sea - Midwater Ring Net (MIK) survey [1]. The MIK survey targets ichthyoplankton and is conducted at night during the quarter 1 (Q1) International Bottom Trawl Surveys (IBTS). Presented data about the gelatinous macrozooplankton community stems from Danish (DTU Aqua), the Swedish (SLU), and German (TI) partners. A total of 158 stations were investigated using a MIK net (2m diameter, 13m long,  1.6mm mesh size with 0.5mm for net end and cod end) [2]. Samples were collected by double oblique hauls from the surface to 5m above the seafloor with a maximum depth of ~100m [2]. Eighteen gelatinous macrozooplankton species were encountered during the Q1 2023 survey. Species encountered are hydrozoans i) Aequorea vitrina, ii) Agalma elegans (siphonophore), iii) Aglantha digitale, iv) Apolemia uvaria (siphonophore), v) Clytia spp., vi) Eutima spp., vii) Leuckartiara octona, viii) Melicertum octocostatum, ix) Muggiaea atlantica (siphonophore) , x) Nanomia cara (siphonophore), xi) Tima bairdii; scyphozoans i) Cyanea capillata and ii) Cyanea lamarckii as well as the ctenophores i) Beroe spp., ii) Bolinopsis infundibulum, iii) Pleurobrachia bachei,  iv) Pleurobrachia pileus, and v) the non-indigenous Mnemiopsis leidyi.

 In total 12,093 individual specimens from samples and sub-samples were analyzed and extrapolated to generate a database with 77,099 records of gelatinous macrozooplankton caught in the investigation area during Q1 2023. For rare species, the entire sample was processed, while abundances were estimated from sub-samples for abundant taxa. Flow meter recordings and maximum net depths during each haul were used to convert raw counts to volume-specific densities (individuals m-3) and area-specific abundances (individuals m-2). Further, size data for the different species were obtained from a total of 5,566 individual gelatinous macrozooplankton organisms. Size data are presented in the accompanying database and were used to calculate species-specific wet weights, using published size-weight regressions [3] and Table 1. In addition, we present spatial wet weight distribution patterns for i) the total gelatinous macrozooplankton community, ii) hydrozoans only, iii) scyphozoans only and iv) ctenophora only. The presented data contribute to a time series describing the gelatinous macrozooplankton diversity and distribution in the extended North Sea area during winter [3,4] and summer [5] and are an important baseline to understand response of jellyfish to climate change.

References: 

[1] ICES. 2024. Working Group on Surveys on Ichthyoplankton in the North Sea and adjacent Seas (WGSINS; outputs from 2023 meeting). ICES Scientific Reports. 6: 15, 62 pp. https://doi.org/10.17895/ices.pub.25212692

[2] ICES, Manual for the Midwater Ring Net sampling during IBTS Q1, Series of ICES Survey Protocols SISP 2 (2017) 25 pp. http://doi.org/10.17895/ices.pub.3434.

[3] L. Køhler, B. Huwer , J.M Pujolar, M. Werner, K. Wikström, A. Wernbo, M. Ovegård, C. Jaspers. Gelatinous macrozooplankton diversity and distribution dataset for the North Sea and Skagerrak/Kattegat during January-February 2021. Data in Brief 44 (2022) 108493.

[4] C.J.D. Jensen, L. G. Køhler, B. Huwer, M. Werner, L. Cieters, C. Jaspers. Biodiversity and distribution of gelatinous macrozooplankton in the North Sea and adjacent waters dataset from winter 2022. Data in Brief. 57 (2024) 111100. https://doi.org/10.1016/j.dib.2024.111100.

[5] C. Gawinski , B. Huwer , P. Munk , C. Jaspers , Biodiversity of gelatinous macrozooplankton: Quantitative assessment of data and distribution patterns in the southern and central North Sea during August 2018, Data in Brief 25 (2019) 104186.