The ecology of algae in relation to river water quality surveillance
The broad objectives of the work were to develop standard
methods for the routine biological surveillance of river water
quality, using the non-planktonic algae.
Studies on sampling methodology indicated that natural
substrata should be sampled directly wherever possible, but for
routine purposes, only a semi-quantitative approach was found to
be feasible. Artificial substrata were considered to be useful
for sample collection in deeper waters, and of three different
types tested, Polythene strips were selected for further
investigation essentially on grounds of practicality. These were
tested in the deeper reaches of a wide range of river types and
water qualities: 28 pool sites in 14 different rivers were studied
over a period of 9 months. At each site, the assemblages
developing on 3 strips following a 4, or less commonly, an 8 week
immersion period were analysed quantitatively. Where possible,
the natural substrata were also sampled semi-quantitatively at each
site. and at a nearby riffle. The results of this survey were
very fragmentary: many strips failed to yield useful data, and
the results were often difficult to interpret. and of limited value
for water quality surveillance purposes.
In one river. the Churnet, the natural substrata at 14
riffle sites were sampled semi-quantitatively on 14 occasions at
intervals of 4 weeks. In this survey, the results were more
readily interpreted in relation to water quality, and no special
data processing was found to be necessary or helpful.
Further studies carried out on the filamentous green alga
Cladophora showed that this alga may have some value as a
bioaccumulation indicator for metals, and as a bioassay
organism for the assessment of the algal growth promoting potential
of natural river waters.