What is the title of the paper? Regional climate change and harmful algal blooms in the northeast
Atlantic
Who wrote the paper and where is it published? Martin Edwards, David Johns, Sophie Letreme, E
Svendsen and Ant Richardson.
What is this about? An investigation into why some areas of the north east Atlantic and North Sea
have high numbers of phytoplankton that can produce Harmful Algal Blooms (HABs). Is this due to
an increase in nutrients (eutrophication), or a response to a change in climate?
Why is it important? Eutrophication is the enrichment of water with nutrients from the land and
can be a serious threat to near shore ecosystems. Eutrophication has been linked to an increase in
the occurrence of phytoplankton species that can cause HABs. HABs can have important ecological
and economic consequences on the health of the marine coastal habitats, their flora and fauna and
can endanger human health through shellfish poisoning.
Why does it matter? Some scientists have suggested that HAB species are increasingly globally due
to anthropogenic influences and others have suggested the cause is due to climate change. The CPR
survey provides long term spatial (space) and temporal (time) data so that the two influences can be
distinguished from one another.
It is important to note that an increase phytoplankton species and HABs abundance due to an
increase in nutrients can have a natural explanation.
What does the paper tell us?
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HABs species have been increasing but only in specific areas and habitats.
That climate variability and regional climate warming have a dominant effect on the long
term trends in phytoplankton assemblages and biomass.
Hydro climatic changes that have occurred since the late 1980s have resulted in an
environment that favours the growth of some HAB forming phytoplankton species (mainly
dinoflagellates and flagellates). Dinoflagellates are also emerging earlier in the season.
In the North Sea dinoflagellate abundance is positively related to changes in the Sea Surface
Temperature (SST) and the North Atlantic Oscillation (NAO), which means that changes in
the environment and climate are having an effect on the numbers of HAB forming species.
Similar events were recorded in the Baltic Sea in the late 1980s
If these climatic conditions persist and SST continues to rise, the resulting environment may
favour dinoflagellate species instead of diatoms. This will lead to a shift in species
composition, with earlier and more frequent dinoflagellate blooms forming in the North Sea.
An increase in annual rainfall (due to the positive values of the NAO) has increased the
runoff of nutrients into the coastal habitats around the Norwegian coast.
This coupled with low salinity levels and warmer temperatures has further enhanced the
formation of phytoplankton blooms in this area.
It appears that the geography of the countries boarding the east North Sea is also providing
favourable habitats for the formation of phytoplankton blooms at certain times of the year
and explains the spatial variability of bloom occurrence.
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It is important that nutrient input that can be attributed to human activities should be
monitored more closely in these areas.
HABs are natural occurrence although their timing and longevity is a effected by climatic
variations, nutrient levels and human activities.
The paper highlights the need for long term ecological studies like the CPR survey to provide
a monitoring tool for HABs.