Algae as Bioindicators - Freshwater Algae: Identification, Enumeration and Use as Bioindicators - page 118

Ta b l e 3 . 6 Organic Pollution at Selected Sites: Application of Palmer's (1969) Indices.

Pollution
Rating Aquatic Site Recorded Genera High Organic Pollution

Sewage stabilisation pond Ankistrodesmus, Chlamydomonas, Chlorella,

Cyclotella, Euglena, Micractinium,
Nitzschia, Phacus, Scenedesmus

25 Clear supporting evidence

Greenville Creek, Ohio Euglena, Nitzschia, Oscillatoria, Navicula,

Synedra

18 Probable

Grand Lake, Ohio Anacystis, Ankistrodesmus, Melosira,

Navicula, Scenedesmus, Synedra

13 No evidence

Lake Salinda, Indiana Chlamydomonas, Melosira, Synedra 7 No organic enrichment

Source: Palmer, 1969. Reproduced with permission of John Wiley and Sons Ltd.
See text for calculation of pollution rating.

diatoms in the assessment of river water quality
(Section 3.4.5).

acid deposition and acidification of lakes in various
parts of Central and Northern Europe.
Central Europe. In Central Europe, regional emis-
sions of S(SO 4 ) and soluble inorganic N(NO 3 ,NH 4 )
compounds reached up to ∼280 mmol m −2 year −1
between 1940 and 1985, then declined by ∼80%
and ∼35% respectively during the 1990s (Kopacek
et al ., 2001). This atmospheric deposition led to acid
contamination of catchment areas and the resulting
acidification of various Central European mountain
lakes, including a group of eight glacial lakes in the
Bohemian Forest of the Czech Republic (Vrba et al .,
2003; Nedbalova et al ., 2006).
Studies by Nedbalova et al . (2006) on chronically
acidified Bohemian Forest lakes have demonstrated
some recovery from acid contamination. This is now
beginning, about 20 years after the reversal in acid
deposition that occurred in 1985, with some lakes
still chronically acid - but others less acid and in
recovery mode (Table 3.7). Chronically acid lakes
have low primary productivity, with low levels of
phytoplankton and zooplankton and domination by
heterotrophic bacteria. Lakes in recovery mode have
a higher plankton standing crop, which is domi-
nated by phytoplankton and zooplankton rather than
bacteria.
Phytoplankton species composition is charac-
terisedbyacid-tolerantoligotrophicunicellularalgae.
Lakes in recovery mode are still acid and have a

Acidity

Acidity becomes an important aspect of lake water
quality in two main situations - naturally occurring
oligotrophic waters and in cases of industrial pol-
lution. Algal bioindicators have been important for
monitoring lake pH change both in terms of lake
sediment analysis (fossil diatoms, Section 3.2.2) and
contemporary epilimnion populations - see below.

Oligotrophic waters The tendency for olig-
otrophic lakes to be slightly acid has already been
noted in relation to nutrient status (Section 3.2.3), and
for this reason, many algae typical of low-nutrient
waters - including various desmids and species of
Dinobryon (Table 3.3) - are also tolerant of acidic
conditions. Acidic, oligotrophic waters tend to be
low in species diversity. In a revised classification of
British lakes proposed by Duker and Palmer (2009),
naturallyacidlakesincludehighlyacidbog/heathland
pools (group A), acid moorland pools and small lakes
(B) and acid/slightly acid upland lakes (group C).

Industrial acidification of lakes Industrial
atmospheric pollution during the last century led to