Surface nutrients,chlorophyll a and phaeopigment in some Scottish sea lochs

The distribution of several surface properties, both physical and chemical, of three Scottish sea lochs were studied during the spring phytoplankton bloom.Concentrations of nitrate, phosphate, and silicate have been determined and related to fluctuations in the freshwater input and uptake by the phytoplankton population. The ratios nitrate: phosphate and silicate: phosphate (on atom bases) in Loch Creran and Loch Linnhe were similar, but there were certain marked differences from those in Loch Etive.Nitrate, rather than phosphate, was a critical factor in the productivity of Loch Creran and Loch Linnhe. In Loch Etive the limitation of these nutrients was directly affected by the amount of fresh-water entering into the Loch.Patchiness of chlorophyll a and phaeopigments in Loch Creran and Loch Etive reflected those factors (e.g., freshwater/sea-water inflow, turbulence produced by the loch topography etc.) which affect the surface circulation in the two lochs.The delay in the development of the phytoplankton bloom in Loch Linnhe may be attributed to a poor stability of the surface layers due to low run-off.