Drivers and effects of Karenia mikimotoi blooms in the western English Channel

Barnes, MKS, Tilstone, GH, Smyth, TJ, Widdicombe, CE, Gloël, J, Robinson, C, Kaiser, J and Suggett, DJ 2015 Drivers and effects of Karenia mikimotoi blooms in the western English Channel. Progress in Oceanography, 137. 456-469.

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Naturally occurring red tides and harmful algal blooms (HABs) are of increasing importance in the coastal environment and can have dramatic effects on coastal benthic and epipelagic communities worldwide. Such blooms are often unpredictable, irregular or of short duration, and thus determining the underlying driving factors is problematic. The dinoflagellate Karenia mikimotoi is an HAB, commonly found in the western English Channel and thought to be responsible for occasional mass finfish and benthic mortalities. We analysed a 19-year coastal time series of phytoplankton biomass to examine the seasonality and interannual variability of K. mikimotoi in the western English Channel and determine both the primary environmental drivers of these blooms as well as the effects on phytoplankton productivity and oxygen conditions. We observed high variability in timing and magnitude of K. mikimotoi blooms, with abundances reaching >1000 cells mL�1 at 10 m depth, inducing up to a 12-fold increase in the phytoplankton carbon content of the water column. No long-term trends in the timing or magnitude of K. mikimotoi abundance were evident from the data. Key driving factors were identified as persistent summertime rainfall and the resultant input of low-salinity high-nutrient river water. The largest bloom in 2009 was associated with highest annual primary production and led to considerable oxygen depletion at depth, most likely as a result of enhanced biological breakdown of bloom material; however, this oxygen depletion may not affect zooplankton. Our data suggests that K. mikimotoi blooms are not only a key and consistent feature of western English Channel productivity, but importantly can potentially be predicted from knowledge of rainfall or river discharge.

Item Type: Publication - Article
Subjects: Biology
Earth Observation - Remote Sensing
Divisions: Plymouth Marine Laboratory > National Capability categories > Western Channel Observatory
Depositing User: Gavin Tilstone
Date made live: 15 Sep 2015 14:41
Last Modified: 09 Nov 2018 10:25

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