Environmental drivers of a decline in a coastal zooplankton community

Abstract

Major changes in North Atlantic zooplankton communities in recent decades have been linked to climate change but the roles of environmental drivers are often complex. High temporal resolution data is required to disentangle the natural seasonal drivers from additional sources of variability in highly heterogeneous marine systems. Here, physical and plankton abundance data spanning 2003–2017 from a weekly long-term monitoring site on the west coast of Scotland were used to investigate the cause of an increasing decline to approximately -80± 5% in annual average total zooplankton abundance from 2011 to 2017. Generalized additive mixed models (GAMMs), with an autoregressive correlation structure, were used to examine seasonal and inter-annual trends in zooplankton abundance and their relationship with environmental variables. Substantial declines were detected across all dominant taxa, with ∼ 30–70% of the declines in abundance explained by a concurrent negative trend in salinity, alongside the seasonal cycle, with the additional significance of food availability found for some taxa. Temperature was found to drive seasonal variation but not the long-term trends in the zooplankton community. The reduction in salinity had the largest effect on several important taxa. Salinity changes could partly be explained by locally higher freshwater run-off driven by precipitation as well as potential links to changes in offshore water masses. The results highlight that changes in salinity, caused by either freshwater input (expected from climate predictions) or fresher offshore water masses, may adversely impact coastal zooplankton communities and the predators that depend on them.

Environmental stability and phenotypic plasticity benefit the cold-water coral Desmophyllum dianthus in an acidified fjord

“…Due to high environmental variability in shallow waters of Comau Fjord, corals are likely to feed less during periods of elevated temperatures, as suggested by the low prey capture rates of Lophelia pertusa and Madrepora oculata in laboratory experiments at higher temperatures (17 °C) 80 , which are probably a consequence of lower polyp activities. Fluctuating physico-chemical conditions may also alter zooplankton communities both in abundance and composition 81 , 82 . For instance, changes in salinity may result in the reduction in coastal zooplankton as osmotic stress can be lethal for some zooplankton groups 82 .…”

“…Fluctuating physico-chemical conditions may also alter zooplankton communities both in abundance and composition 81 , 82 . For instance, changes in salinity may result in the reduction in coastal zooplankton as osmotic stress can be lethal for some zooplankton groups 82 . In deep waters (300 m) of Comau Fjord, zooplankton abundance and biomass are low throughout the year and show only low diel variations 48 .…”

Lipid biomarkers reveal trophic relationships and energetic trade‐offs in contrasting phenotypes of the cold‐water coral Desmophyllum dianthus in Comau Fjord, Chile

“…Cyclopoida; with known FATM characteristics such as high 16:0 and 14:0 FAlc, 16:0 FA visible in shallow corals, Lischka & Hagen, 2007), whereas others are more sensitive (Magouz et al., 2021). This may also affect the zooplankton abundance (Laprise & Dodson, 1994; Wells et al., 2021), potentially restricting certain zooplankton groups to deeper waters, which lead to more fine‐scale distributions and contribute to benthic patchiness. As the available plankton data derive from integrated plankton tows across the upper 50 m of the water column (Garcia‐Herrera et al., 2022), they are too coarse to elucidate small‐scale patterns and can only serve as first approximations of the shallow zooplankton community.…”

Metabarcoding analysis of marine zooplankton confirms the ecological role of a sheltered bight along an exposed continental shelf

“…Flow velocity and direction, and gradients in water temperature, salinity and density all contribute to patterns of zooplankton distribution (Ockhuis et al, 2017;Pinti et al, 2019;Wells et al, 2021), whereas smaller scale aggregations, patches and layers are facilitated by vertical migrations, predator avoidance, feeding and mating (Falkenhaug et al, 1997;Gliwicz, 1986;Hays, 2003).…”

“…Zooplankton have high taxonomic diversity and abundance and are distributed unevenly in oceans, with dispersal and aggregation driven by a combination of physical processes and biological interactions at different spatial scales (Folt & Burns, 1999; McManus & Woodson, 2012; Pinel‐Alloul, 1995). Flow velocity and direction, and gradients in water temperature, salinity and density all contribute to patterns of zooplankton distribution (Ockhuis et al, 2017; Pinti et al, 2019; Wells et al, 2021), whereas smaller scale aggregations, patches and layers are facilitated by vertical migrations, predator avoidance, feeding and mating (Falkenhaug et al, 1997; Gliwicz, 1986; Hays, 2003).…”