Major shift in the copepod functional community of the southern North Sea and potential environmental drivers

Abstract

Copepods form the bulk of secondary production in marine ecosystems and are a major resource for higher trophic levels. Copepods are highly sensitive to environmental changes as they are ectotherms with a short life span whose metabolism and development depend on abiotic conditions. In turn, changes in their functional structure (i.e. functional trait composition) can have impacts on ecosystems. We examined changes in the copepod functional community in the North Sea over the past five decades, using a trait-based approach. We observed a shift around 1986–1988: the copepod community was initially dominated by larger herbivores, with a long development time, diapause ability, and highest abundances in summer. This community changed abruptly after 1986–1988, to a dominance of smaller carnivore taxa, with shorter development times, less ability to enter diapause, and that display higher abundances in autumn. This rapid reorganization could be driven by higher water temperatures, lower dinoflagellate abundances, and lower nutrient concentrations. These changes could impact adjacent trophic levels, such as phytoplankton on which several species graze or fish larvae, leading to a mismatch situation with consequences for fish recruitment. Our results emphasize the impact that global and regional changes could have on coastal ecosystems through the role played by copepods.

A multiple baseline approach for marine heatwaves

“…However, we found that the shifting baseline did not fully remove the temporal patterns and instead found a shift from the 1980s (characterized by only a few strong heatwaves) to the 1990-2007, which contained two of the three severe events and twice as many strong heatwaves per decade than any other period of the time series. The end of the decade of the 1980s and the 1990s was characterized by important changes in the Northern Hemisphere (Beaugrand et al 2015), including North Sea phytoplankton (Defriez et al 2016;Di Pane et al 2022) and zooplankton (Kirby et al 2007;Deschamps et al 2023). In the German Bight, the copepod assemblages shifted from a dominance of summer, long-lived herbivores to autumn, short-lived carnivores (Deschamps et al 2023).…”

“…The end of the decade of the 1980s and the 1990s was characterized by important changes in the Northern Hemisphere (Beaugrand et al 2015), including North Sea phytoplankton (Defriez et al 2016;Di Pane et al 2022) and zooplankton (Kirby et al 2007;Deschamps et al 2023). In the German Bight, the copepod assemblages shifted from a dominance of summer, long-lived herbivores to autumn, short-lived carnivores (Deschamps et al 2023). We cannot ascribe those changes to marine heatwaves; nutrients are hypothesized to have contributed to the change at least for phytoplankton (Di Pane et al 2022).…”

Unraveling Functional Diversity Patterns in Hyporheic Zones: A Trait-Based Approach Applied to Copepods from the Rio Gamberale Creek

“…Phosphate often dictates the growth of algae and other autotrophic organisms. Variations in feeding traits might be directly linked to how copepods exploit these resources, with herbivorous copepods particularly favored in environments where phosphate-induced algal blooms occur [70]. Conversely, species that primarily feed on microorganisms-located on the right side of the first axis-may be influenced by sulfate concentrations.…”

Global Change Alters Coastal Plankton Food Webs by Promoting the Microbial Loop: An Inverse Modelling and Network Analysis Approach on a Mesocosm Experiment

“…Plankton organisms form the base of pelagic marine food webs and are particularly sensitive to ecosystem changes. For instance, warming and changes in dissolved nutrient concentrations in coastal seas observed over the past decades have altered phytoplankton and zooplankton assemblages, marked by shifts in their taxonomic and functional structure, with consequences for the entire ecosystem such as nutrient turnover and fish recruitment (Alvarez-Fernandez et al, 2012;Capuzzo et al, 2018;Di Pane et al, 2022;Di Pane et al, 2023;Marques et al, 2023;Deschamps et al, 2023). However, less is known on how environmental changes could further impact coastal plankton communities, and especially on the combined impact of multiple drivers (Sommer et al, 2015;Garzke et al, 2016;Horn et al, 2020).…”