BOTTOM FAUNA OF BLACKWATER ESTUARY: 1970 263
A Survey of the Bottom Fauna
of the Blackwater Estuary: 1970
Dr R. S. K. Barnes and J. Coughlan
(C.E.R.L. Marine Biological Laboratory, Fawley, Southampton,
S04 1TW)
Summary
A number of additions and corrections are made to the
Blackwater Estuary fauna list. Distribution patterns revealed
by a survey of the benthic fauna of the Blackwater Estuary in
May 1970 are described, and changes in the frequency of occur-
rence of a number of species between 1960 and 1970 are dis-
cussed. It is concluded that the fauna of the region has, to a
large extent, recovered from the severe winters of 1961-62 and
1962-63.
Introduction
The paper by Davis (1967), providing a fauna list for the
Blackwater Estuary and adjacent regions, was based on studies
by personnel of the Biology Section of the Central Electricity
Research Laboratories, Leatherhead, and of the Ministry of
Agriculture, Fisheries and Food, up to and including 1965. A
similar paper on the marine algae was published by Milligan
(1966). A further survey of this region was conducted by the
two present authors from the 11th to the 23rd of May 1970.
The aims of this survey were, in a large part, to see how the
region was recovering from the severe winter of 1962-1963,
which had marked effects on the distribution and abundance of a
number of the local species (Davis, loc. cit.), as it did elsewhere
(Crisp, 1964).
This paper presents a summary of the results of that survey.
It concentrates on three points: first, additions and corrections
to Davis's fauna list (loc. cit.); secondly, over-all distribution pat-
terns exhibited by the macrobenthos; and lastly, the frequency
of occurrence of a number of the commoner members of the
fauna, which are regarded as "key species" with respect to the
effects of the severe winter.
Methods
The area investigated is shown by Fig. 1, it extending from
the region of Thirslet Creek, within the Blackwater Estuary, to