Research Output

An Investigation into changes in the phytoplankton community in Loch Creran, a Scottish sea loch.

  Short term and irregular sampling in Loch Creran over recent decades suggested
that changes may be occurring in the phytoplankton community in the loch. This
study sought to confirm this suggestion. After instigating a regular sampling regime
during 2008 and 2009 it became clear that significant changes had occurred, relative
to information from the 1970s, in both the numbers of phytoplankton in the loch and
in their biomass, particularly during the time of the spring bloom. Utilising a tool to
assess change in the phytoplankton community, it also became clear that significant
changes had occurred in the composition of the phytoplankton in Loch Creran.
Work was undertaken to explore possible explanations behind these changes.
The e�ect that toxic, anti-fouling compounds, arising from an increase in leisure
boating in Loch Creran, were having on the productivity of phytoplankton in the
loch was considered by adapting an existing assimilative capacity model for phytoplankton
growth. It was found, that at present levels of boating activity, the concentration
of anti-fouling products present in the loch, would not be great enough
to significantly impact on phytoplankton growth.
Nutrient samples collected during 2009 showed no significant changes in the concentration
of silicate or nitrate in the loch, but phosphate levels were found to be
significantly lower. A review of the e�ects of grazing on phytoplankton by farmed
mussels in Loch Creran indicated that, at current levels, this would not account for
the decrease in phytoplankton numbers observed in the loch.
Significant changes were observed in the water temperature in the loch and in the
intensity and pattern of local rainfall. Increased levels of rainfall in the first three months of the year were found to be high enough to influence the rate of flushing and the rate of phytoplankton washout from the loch. A correlation was found
between the availability of light in the surface layers of the loch and the concentration
of phytoplankton present in these layers. This correlation was found to
exist, throughout the year and not only, as previously thought, during the winter
In conclusion, the observed decline in phytoplankton numbers in Loch Creran, was
attributed to changes in local weather patterns, that had an impact on the physical
structure of the water column, washout rates, the pattern and intensity of heterotrophic
grazing and the availability of light.

  • Type:


  • Date:

    30 November 2011

  • Publication Status:


  • Library of Congress:

    QH301 Biology

  • Dewey Decimal Classification:

    577.7 Marine ecology


Whyte, C. T. in Loch Creran, a Scottish sea loch. (Thesis)


phytoplankton; weather patterns; environment; Loch Creran;

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