ECOLOGICAL STUDIES IN SOUTH BENFLEET CREEK 295
pH
The pH at low water in Benfleet Creek is: —
7.7 on the Transect in Area G—Benfleet Bridge
7.6 on the Transect in Area B—Leigh Island
Time did not permit a complete range of samples to be taken,
for example from transect in area B but a number of points are
indicated by Table II.
Water content of the substratum is dependent on three major
factors: —
1. Period of exposure between tides.
2. Distribution of particle size.
3. Efficiency of packing.
And on two minor factors: —
1. Climatic conditions at the time of sampling.
2. Degree of slope.
If on each of the transects, i.e. in Area B and G, particle size
and efficiency of packing were the same then the water content
would increase towards low tide. This is suggested in Transect
B. The slight variations from this gradation can be explained
in terms of the differences in substrate composition.
There is much greater variation in water content in the
transect in area G, and here all three factors are important. It
may be concluded that the water content of stations 2 and 3 is
a reflection of particle size, or soil composition. The result
obtained for station 1 is very high because it is only a few yards
above low water mark and is therefore only exposed for a short
period. The result for station 4, on the other hand, is very low
because at the time of sampling the station had not been covered
for a few days by the Neap Tides. As a result of this, and the
climatic conditions for the period August 24-31st (approx. period
of Neap Tides) the surface had almost completely dried out and
was cracked and sunbaked.
Random samples were taken in areas A, B and E in order to
give an indication of the water content of these areas, and the
same applies for the Long Transect.