Interannual variability of gelatinous mesozooplankton in a temperate shelf sea: greater abundance coincides with cooler sea surface temperatures

Abstract

Although gelatinous zooplankton are an important component of marine ecosystems, gelatinous mesozooplankton that are <2 cm are underrepresented in monitoring programmes. Here, the interannual variability of gelatinous mesozooplankton abundance and diversity was estimated from 167 zooplankton net samples that were collected in the Celtic Sea during seven fisheries surveys between 2007 and 2019 and analysed alongside environmental parameters. Compositional changes occurred interannually, including an overturn in the abundance ratio of two siphonophores (Muggiaea atlantica and Agalma elegans). Analysis of annual mean gelatinous abundance revealed no linear trend over time (Spearman, r = −0.09, p = 0.287); however, the interannual abundance varied by a factor of 33 (minimum mean abundance in 2013 = 7.36 ± 4.86 individuals m−3; maximum in 2017 = 244.82 ± 84.59 individuals m−3). Holoplanktonic taxa dominated the abundance of the gelatinous community (93.27%) and their abundance was negatively associated with summer sea surface temperature (represented by the 16°C isotherm in July), and the Eastern Atlantic Pattern index 3 months prior (April). Our data suggest that gelatinous mesozooplankton in the Celtic Sea may become less abundant with further ocean warming, and further highlight the need to monitor gelatinous mesozooplankton with a high taxonomic resolution moving forward.

Leveraging Transfer Learning and U-Nets Method for Improved Gap Filling in Himawari Sea Surface Temperature Data Adjacent to Taiwan

“…Variations in SST play a key role in the exchange of energy and moisture between the atmosphere and the ocean [3,4]. SST databases, established using geospatial artificial intelligence computations, are vital for accurately monitoring SST changes to understand and predict the dynamics of climate change, oceanic processes [3], and the overall health of the marine ecosystem [5][6][7][8]. With the advent of satellite technology, satellite-derived SST data have become an essential resource for studying global oceanic and atmospheric phenomena.…”

Oceanic Fronts Shape Biodiversity of Gelatinous Zooplankton in the European Arctic

“…Additional support for using the GZ, as a model system to study the ecology at the passive fronts, comes with the existence of a solid baseline of their diversity in the North Atlantic (Licandro et al, 2015;Hosia et al, 2017) and the European Arctic (Mańko et al, 2015;Ronowicz et al, 2015;Mańko et al, 2020). Unfortunately, the GZ is either completely absent from the local zooplankton time series, or the taxonomic resolution of their records is insufficient (Long et al, 2021), due to their fragile body structure that often damages when sampled harshly. From a broader perspective, the recent recognition of the GZ's trophic importance (Hays et al, 2018;Lüskow et al, 2021) as well as their diverse roles in the biogeochemical cycles (Wright et al, 2021) and the biological pump (Lebrato et al, 2019) renders understanding of the factors structuring their community pivotal for monitoring marine ecosystems and forecasting their climatemediated evolution.…”

Atlantification alters the reproduction of jellyfish Aglantha digitale in the European Arctic

“…Any conclusions on A. digitale phenology are hampered by the overwhelming lack of jellyfish data in planktonic time series (discussed in Long et al 2021), attributable mostly to the historical assumption of the low trophic importance of gelatinous animals (Lüskow et al 2021) that led to the identification of only more abundant, hard‐bodied taxa from samples. Unfortunately, even when A. digitale was included in polar zooplankton time series, its population structure was unassessed (Weydmann et al 2014; Carstensen et al 2019), or routine sampling was too shallow (Mańko et al 2020), which hampered having a thorough understanding of the fate of A. digitale in the European Arctic.…”