Tag: environment

New study shows that climate change affects the activation of plankton resting stages with consequences for community composition and trophic mismatch

Posted on by monikawinder

A large majority of plankton species overwinter as resting stage in the sediment. The resting life stage is, however, often overlooked in climate change research, although emergence of planktonic organisms originating from resting stages from the sediment is a key driver for pelagic population dynamic and community composition.

Here we ask to what extent the recruitment of plankton resting stages is affected by proposed climate change. For this, we investigated  phyto- and zooplankton recruitment from oxic sediments in the Baltic Sea in a controlled experiment under proposed temperature and light increase during the spring and summer. 

We find that emergence of resting stage differs between seasons and the abiotic environment. Phytoplankton recruitment from resting stages were high in spring with significantly higher emergence rates at increased temperature and light levels for dinoflagellate and cyanobacteria than for diatoms, which had highest emergence under cold and dark conditions. In comparison, hatching of copepod nauplii was not affected by increased temperature and light levels. These results show that activation of plankton resting stages are affected to different degrees by increasing temperature and light levels, indicating that climate change affects plankton dynamics through processes related to resting stage termination with potential consequences for bloom timing, community composition and trophic mismatch.

You can find the full article here:

Hedberg P, Olsson M, Höglander H, Bruchert V, Winder M (2024) Climate change effects on plankton recruitment from coastal sediments. Journal of Plankton Research. https://doi.org/10.1093/plankt/fbad060

Investigating recruitment of resting stages from Baltic Sea sediments. Foto: Per Hedberg.

Ocean acidification study shows high resilience of a coastal plankton community

Posted on by monikawinder

Rossoll, D., Sommer, U. & Winder, M. Community interactions dampen acidification effects in a coastal plankton system. Mar Ecol Prog Ser 486, 37–46 (2013).

Changing seawater chemistry towards reduced pH as a result of increasing atmospheric carbon dioxide (CO2) is affecting oceanic organisms, particularly calcifying species. Responses of non-calcifying consumers are highly variable and mainly mediated through indirect ocean acidification (OA) effects induced by changing the biochemical content of their prey, as shown within single species and simple two-trophic interactions. However, it can be expected that indirect CO2 impacts observed at the single species level are compensated at the ecosystem level by species richness and complex trophic interactions. A dampening of CO2-effects can be further expected for coastal communities adapted to strong natural fluctuations in pCO2, typical for productive coastal habitats.

Here we show that a plankton community of the Kiel Fjord was tolerant to pCO2 levels projected by the end of this century (<1400 µatm), and only subtle differences were observed at extreme high values of 4000 µatm. We found similar phyto- and microzooplankton biomass and copepod abundance and egg production across all CO2 treatment levels. Stoichiometric phytoplankton food quality was minimal different at the highest pCO2 treatment, which was however far from being potentially limiting for copepods. These results contrast studies including single species that observed strong indirect CO2 effects for herbivores, suggesting limitations of biological responses at the organism to the community level. Although this coastal plankton community was highly tolerant to high fluctuations in pCO2, increase in hypoxia and CO2 uptake by the ocean can aggravate acidification and may lead to pH changes outside the experienced range for coastal organisms.