Whittaker, J.E. 1980 The Fleet, Dorset - a seasonal study of the watermass and its vegetation. Proceedings of the Dorset Natural History and Archaeological Society, 100 (for 1978).

Hourly water samples were taken, and measurements made of salinity, pH, calcium, magnesium, dissolved oxygen and temperature. Tidal measurements were made at half hourly intervals over 12-13 hours. A preliminary bathymetric map was also produced.

Seasonal pH ranges in the Fleet present a picture of high alkalinity of Fleet waters, especially in spring and summer months - pH mean of 7.8 in autumn and winter, but around 8.5 or higher in spring and summer (pH of seawater is 7.8-8.2). This is considered to be due to photosynthesis by Zostera in shallow waters - highest values occurred on Zostera flats, with lowest values around Abbotsbury in summer and autumn when water stagnates, and Zostera is rare. In august 1969 the water of West Fleet was dark brown with a lower pH than normal, with associated fish mortality. This was attributed to a phytoplankton bloom, possibly triggered by farm pollution. A similar occurrence was reported to have occurred during the severe drought of 1976.

Dissolved oxygen values of >200% saturation were recorded from the Fleet in spring and summer, assumed to be due to photosynthesis by Zostera. Values of >150%, however, were also recorded during winter when Zostera has died back. These were attributed to colder water being able to take up more oxygen.

Calcium and magnesium values showed a simple linear relationship with salinity.

Freezing of the Fleet was reported for winter 1963. Diurnal variations in water temperature of >5EC from early morning to late afternoon were reported.

AMarine algae and Zostera occur in luxuriant abundance in the Fleet for much of the year; only in winter and spring are there large tracts of bare mud. Zostera dies back by late June. Green algae are particularly common in the lower salinities of West Fleet where many species form dense mats of vegetation on the beds of Zostera and often cover large tracts of the water surface in spring. ... Epiphytic growth on all seaweeds and Zostera is very well developed@. Ulva is reported as abundant from March to April, especially in the lower salinities, with >flannel weed= (a number of filamentous species of mainly Cladophora and Enteromorpha species with some reds), which dies back in late autumn and may often be washed ashore in gales. Chaetomorpha spp. grows mainly in the low salinities around Abbotsbury, and, to a lesser extent, as far as Lynch Cove. It is most noticeable in late spring and summer. Two species of Zostera are recorded from the Fleet, the more common Z. angustifolia, and Zostera nana. AZostera marina is not found in the Fleet, but it does occur in Weymouth Bay.@ ARuppia also occurs in West Fleet@.

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