Temperature-induced copepod depletion and the associated wax of Bellerochea in Belgian coastal waters: Implications and shifts in plankton dynamics
Since 2018, severe and recurrent copepod depletions have been observed in Belgian coastal waters. These depletions have been described as temperature-induced mass mortality events. This paper confirms the relation of copepod abundance anomalies with periods of high temperature based on new data. Alt...
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| Published in: | Journal of sea research Vol. 201; p. 102523 |
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| Main Authors: | , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier B.V
01-10-2024
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Since 2018, severe and recurrent copepod depletions have been observed in Belgian coastal waters. These depletions have been described as temperature-induced mass mortality events. This paper confirms the relation of copepod abundance anomalies with periods of high temperature based on new data. Although severe, the effects, consequences and implications of this depletion remain unknown. Our study suggests that the absence of zooplanktonic predators in autumn, together with the availability of nutrients discharged via the Scheldt estuary, allowed a bloom of the diatom Bellerochea, in a season otherwise characterised by low phytoplanktonic activity. Although the bloom reaches high abundances, its effects on the marine environment are not yet visible. The enormous abundances are likely to induce small-scale oxygen depletions which might further translate to the environment. Communities of Calanoida, Canuelloida and Cyclopoida tend to recover from the annual autumn depletion, although the typical autumn peak is entirely missing in the years subject to severe heat waves and associated high water temperatures. As a result, copepod dynamics have drastically changed since the first observed depletion and associated bloom of Bellerochea in 2018.
•Bellerochea blooms emerged in the Belgian part of the North Sea (BPNS) due to temperature-induced copepod depletion.•It is the first documented bloom of Bellerochea in the BPNS•Image-based datasets allow retrospective analysis of unchanged samples, revealing ecosystem changed without decay.•Copepod depletion and Bellerochea blooms intensified, wiht longer durations observed in 2022 compared to 2018.•. Copepod depletion and Bellerochea blooms may reduce oxygen, impacting thropic levels, larval fish and zooplankton in the BPNS ecosytem.•Recurrent copepod depletions and Bellerochea blooms pose challenges to predict ecosystem responses, intensified by global warming and associated heatwaves.•Since 2018, copepod dynamics have shifted, potentially favoring more temperature-resilient species in the ecosystem. |
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| ISSN: | 1385-1101 |
| DOI: | 10.1016/j.seares.2024.102523 |