Future increase in harmful algal blooms in the North Sea due to climate change

2005 ◽  
Vol 51 (5) ◽  
pp. 31-36 ◽  
Author(s):  
L. Peperzak

In temperate seas such as the North Sea harmful (toxic) algal blooms will probably increase as a result of climate change. This conclusion was reached after investigating the projected effect of climate change for the year 2100 in Dutch coastal waters (4°C temperature rise and increased water column stratification) on the growth rates of six harmful and two non-harmful phytoplankton species. Micro algae form the basis of the marine food chain. However, toxin-producing species may seriously disrupt the food web and lead to fish kills and human intoxication. Two species with estimated doubled growth rates in 2100, F. japonica and C. antiqua, entered Europe via ship's ballast water or shellfish imports. This stresses the need to legally regulate such invasion routes in order to prevent the import of novel species. Future toxic phytoplankton blooms may further devaluate ecosystem deliverables such as fish production or recreational use. This devaluation can be estimated by monetary value assessments that are needed in cost-benefit analyses for policy guidance. The lack of understanding of future climate, ecosystem functioning and its response to climate change calls for a scientific effort to improve our knowledge on present day coastal ecosystem functioning and its resilience.

2021 ◽  
Author(s):  
Joanna K. Bluemel ◽  
Simon Fischer ◽  
David W. Kulka ◽  
Christopher P. Lynam ◽  
Jim R. Ellis

2021 ◽  
Vol 163 ◽  
pp. 105230
Author(s):  
Michael Weinert ◽  
Moritz Mathis ◽  
Ingrid Kröncke ◽  
Thomas Pohlmann ◽  
Henning Reiss

2013 ◽  
Vol 10 (5) ◽  
pp. 1525-1557
Author(s):  
K. O'Driscoll ◽  
B. Mayer ◽  
J. Su ◽  
M. Mathis

Abstract. The fate and cycling of two selected legacy persistent organic pollutants (POPs), PCB 153 and γ-HCH, in the North Sea in the 21st century have been modelled with combined hydrodynamic and fate and transport ocean models. To investigate the impact of climate variability on POPs in the North Sea in the 21st century, future scenario model runs for three 10 yr periods to the year 2100 using plausible levels of both in situ concentrations and atmospheric, river and open boundary inputs are performed. Since estimates of future concentration levels of POPs in the atmosphere, oceans and rivers are not available, our approach was to reutilise 2005 values in the atmosphere, rivers and at the open ocean boundaries for every year of the simulations. In this way, we attribute differences between the three 10 yr simulations to climate change only. For the HAMSOM and atmospheric forcing, results of the IPCC A1B (SRES) 21st century scenario are utilised, where surface forcing is provided by the REMO downscaling of the ECHAM5 global atmospheric model, and open boundary conditions are provided by the MPIOM global ocean model. Dry gas deposition and volatilisation of γ-HCH increase in the future relative to the present. In the water column, total mass of γ-HCH and PCB 153 remain fairly steady in all three runs. In sediment, γ-HCH increases in the future runs, relative to the present, while PCB 153 in sediment decreases exponentially in all three runs, but even faster in the future, both of which are the result of climate change. Annual net sinks exceed sources at the ends of all periods.


2018 ◽  
Vol 600 ◽  
pp. 111-126 ◽  
Author(s):  
KB Huebert ◽  
J Pätsch ◽  
M Hufnagl ◽  
M Kreus ◽  
MA Peck

Atmosphere ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 272 ◽  
Author(s):  
Christian Dieterich ◽  
Shiyu Wang ◽  
Semjon Schimanke ◽  
Matthias Gröger ◽  
Birgit Klein ◽  
...  

An ensemble of regional climate change scenarios for the North Sea is validated and analyzed. Five Coupled Model Intercomparison Project Phase 5 (CMIP5) General Circulation Models (GCMs) using three different Representative Concentration Pathways (RCPs) have been downscaled with the coupled atmosphere–ice–ocean model RCA4-NEMO. Validation of sea surface temperature (SST) against different datasets suggests that the model results are well within the spread of observational datasets. The ensemble mean SST with a bias of less than 1 ∘ C is the solution that fits the observations best and underlines the importance of ensemble modeling. The exchange of momentum, heat, and freshwater between atmosphere and ocean in the regional, coupled model compares well with available datasets. The climatological seasonal cycles of these fluxes are within the 95% confidence limits of the datasets. Towards the end of the 21st century the projected North Sea SST increases by 1.5 ∘ C (RCP 2.6), 2 ∘ C (RCP 4.5), and 4 ∘ C (RCP 8.5), respectively. Under this change the North Sea develops a specific pattern of the climate change signal for the air–sea temperature difference and latent heat flux in the RCP 4.5 and 8.5 scenarios. In the RCP 8.5 scenario the amplitude of the spatial heat flux anomaly increases to 5 W/m 2 at the end of the century. Different hypotheses are discussed that could contribute to the spatially non-uniform change in air–sea interaction. The most likely cause for an increased latent heat loss in the central western North Sea is a drier atmosphere towards the end of the century. Drier air in the lee of the British Isles affects the balance of the surface heat budget of the North Sea. This effect is an example of how regional characteristics modulate global climate change. For climate change projections on regional scales it is important to resolve processes and feedbacks at regional scales.


2019 ◽  
Vol 85 (7) ◽  
Author(s):  
Arite Bigalke ◽  
Nils Meyer ◽  
Lydia Alkistis Papanikolopoulou ◽  
Karen Helen Wiltshire ◽  
Georg Pohnert

ABSTRACT Plankton communities consist of complex microbial consortia that change over time. These fluctuations can be only partially explained by limiting resources. Biotic factors such as herbivores and pathogens also contribute to the control of algal blooms. Here we address the effects of algicidal bacteria on a natural plankton community in an indoor enclosure experiment. The algicidal bacteria, introduced into plankton taken directly from the North Sea during a diatom bloom, caused the rapid decline of the bloom-forming Chaetoceros socialis within only 1 day. The haptophyte Phaeocystis, in contrast, is resistant to the lytic bacteria and could benefit from the removal of the competitor, as indicated by an onset of a bloom in the treated enclosures. This cascading effect caused by the bacterial pathogen accelerated the succession of Phaeocystis, which bloomed with a delay of only several weeks in the in situ waters at Helgoland Roads in the North Sea. The algicidal bacteria can thus modulate the community within the limits of the abiotic and biotic conditions of the local environment. Implications of our findings for plankton ecosystem functioning are discussed. IMPORTANCE Plankton communities change on a seasonal basis in temperate systems, with distinct succession patterns; this is mainly due to algal species that have their optimal timing relative to environmental conditions. We know that bacterial populations are also instrumental in the decay and termination of phytoplankton blooms. Here, we describe algicidal bacteria as modulators of this important species succession. Upon treatment of a natural plankton consortium with an algicidal bacterium, we observed a strong shift in the phytoplankton community structure, compared to controls, resulting in formation of a succeeding Phaeocystis bloom. Blooms of this alga have a substantial impact on global biogeochemical and ecological cycles, as they are responsible for a substantial proportion of primary production during spring in the North Sea. We propose that one of the key factors influencing such community shifts may be algicidal bacteria.


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