Thematic session 9 – Climate Change Research in Aquatic Ecosystems

You are here

Thematic Session 9

Climate Change Research in Aquatic Ecosystems

Wednesday 10 February 2021 | 10:00-12:00 hrs


LINK TO ZOOM MEETING: Will Follow soon.


10:00 – 10:05 Introduction by the chairs - Dedmer van de Waal (Senior Researcher Aquatic Ecology @ Netherlands Institute of Ecology) & Qing Zhan (PhD Candidate Aquatic Ecology, Netherlands Institue of Ecology)
10:05 – 10:20 KEYNOTE LECTURE | Climate change affects aquatic ecosystems: lessons learned from studying an ignored component
Sabine Hilt @ Ecosystem Research group, Leibniz Institute for Freshwater Ecology and Inland Fisheries

Climate change impacts affect 80-90% of core ecological processes relevant for ecosystem functioning and services to people in freshwater and marine ecosystems. Despite a rising number of studies, there are large differences in research on climate change effects on aquatic organism groups. Periphyton, the complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus attached to submerged surfaces, is still understudied. This is surprising given its key role for aquatic primary production and ecosystem state. Based on several examples I highlight the need for a more comprehensive understanding of climate change impacts on aquatic organisms as prerequisite to mitigating their influence on biodiversity and ecosystem service provision.
10:20 – 10:30 Effects of a heatwave on morphologically similar temperate and subtropical macrophyte species
Bastiaan Drost @ Aquatic Ecology & Water Quality Management, Wageningen University

Plants react differently to heatwaves compared to constant warming. Heatwaves will increase due to climate change. Shallow ponds react quickly to heating. Macrophytes have important ecosystem services here. However non-native species may cause nuisance. Subtropical macrophytes are grow faster during heatwaves than temperate species, but previous studies investigated morphologically different species. We studied the response of two morphologically similar macrophytes: Elodea nuttallii (temperate) and Egeria densa (subtropical). During a six-week study, plants were subjected to an one-week heatwave. This increased E. densa’s growth while it stayed constant for E. nuttallii. So heatwaves benefit E. densa but not E. nuttallii.
10:30 – 10:40 Effectiveness of phosphorus control under extreme heatwaves: implications for sediment nutrient releases and greenhouse gas emissions
Qing Zhan @ AKWA, Netherlands Institute of Ecology

Climate change and eutrophication are identified as key drivers of water quality deterioration worldwide. Extreme climatic events are suggested to exacerbate the effect of nutrient enrichment in freshwater, through increasing nutrient run-off from terrestrial surfaces during extreme precipitation events as well as increasing mineralization rates during heatwaves. In order to prepare water managers for future global change scenarios, we investigated how the effectiveness of a promising nutrient abatement technique is impacted by an extreme heatwave. To this end, we carried out a three-week sediment-incubation experiment, where we tested the effectiveness of a solid phase phosphorus sorbent, lanthanum-bentonite clay, LMB (Phoslock®) in reducing phosphorus (P) with and without exposure to an extreme heatwave event (increasing from 20 °C to 30 °C) during the second week. The experimental heatwave caused a temporal P-release from the sediments in LMB-treated sediment incubations, without a recovery of the elevated P concentrations until end of the experiment. Whereas LMB addition resulted in a reduction of P concentrations of 85% (relative to the initial P levels) by the end of the experiment under non-heatwave conditions, under heatwave conditions only a reduction of 74% could be achieved. Despite the LMB additions, dissolved greenhouse gas (GHG) concentrations increased during the heatwave. Our study thus indicates that the effectiveness of LMB might be compromised during a heatwave, and that the projected increase in climatic extreme events thus pose an additional challenge for water managers to maintain good water quality.
10:40 – 10:50 Drainage ditches are greenhouse gas hotlines in peat landscapes
Lisanne Hendriks @ Aquatic Ecology and Environmental Biology, Radboud University

Greenhouse gas emissions from peatlands have been extensively studied. Considerably less attention has been paid to the emissions from the infrastructure used to drain peatlands such as ditches. We quantified year-round emissions of (ebullitive and diffusive) methane and carbon dioxide in 10 drainage ditches in intensively-used temperate peatlands. On several occasions nitrous oxide emissions were measured. All ditches were considerable greenhouse gas sources. Ebullition made up nearly half of the total GHG emission. We conclude that ditch emissions should be included in national greenhouse gas reporting, and ebullition should not be omitted.
10:50 – 11:10 Joint coffee / tea break and time to socialise within your breakout room
11:10 – 11:20 Come rain, come shine: peatland carbon dynamics under extreme precipitation
Janna Barel @ Laboratoire Ecologie Fonctionelle et Environnement, Université de Toulouse, CNRS

Extreme rainfall has become more and more common. However, the consequences of increasingly intense, but less frequent rainfall events are poorly understood. Peatlands are highly depended on water. How do these immense stocks of carbon withstand and recover from extreme rainfall? We tested the resistance and resilience of peatland carbon dynamics to extreme precipitation in mesocosms. Extreme precipitation regimes destabilise water table dynamics, with cascading effects on peatland carbon fluxes. Yet, peatland carbon dynamics might be more resilient than expected as vascular plants can compensate for the lost functioning of the peat moss.
11:20 – 11:30 Temperature variation modulates the toxic effects of a pesticide under warming on an aquatic ecosystem function
Charlotte Theys @ Evolutionary Stress Ecology and Ecotoxicology, KU Leuven

Evidence is growing that increasing mean temperatures and daily temperature fluctuations (DTF) may increase pesticide toxicity. We examined effects of the pesticide chlorpyrifos under an increased mean temperature and in presence of DTF on life-history traits (mortality and growth rate) and one important ecosystem function (leaf degradation) in the freshwater isopod Asellus aquaticus. Chlorpyrifos reduced isopod growth rate when both a higher mean temperature and DTF were present. Leaf consumption of pesticide-exposed isopods increased at high mean temperature, yet, lowered again towards control levels when DTF was induced. These altered traits may impact the ecosystem function of nutrient recycling.
11:30 – 11:40 Seasonal changes in presence and body size of brown shrimp Crangon crangon on intertidal flats in the western Dutch Wadden Sea
Emma Penning @ Coastal Systems, Netherlands Institute for Sea Research (NIOZ)

The early life stages of brown shrimp Crangon crangon depend on intertidal flats, which serve as their nurseries upon settlement after a pelagic larval phase. Settlement starts earlier after mild winters vs cold winters but long term trends in timing of shrimp settlement on the mudflats remain unknown. We analyzed 35 years (1984-2018) of shrimp monitoring in May-June, and observed advanced shrimp settlement on intertidal flats in the westernmost Dutch Wadden Sea. In addition we investigated which time of the year is most important in explaining the timing of settlement of shrimp on mudflats.
11:40 – 11:55 General discussion and wrap up of the session