Environmental Engineering Reference
In-Depth Information
Dogma, 1975; Karling, 1946 , 1966 ; Milanez,
1966 ), Hyphochytrium (Ayers and Lumpsden,
1977 ), Olpidiopsis (Holland, 1958 ; Howard and
Johnson, 1969 ; Khulbe and Bhargava, 1981 ;
Milanez, 1966 ; Milanez and Beneke, 1968 ;
Miller, 1965 ; Scott, 1960 ; Scott et al., 1963a ;
Shanor, 1940 ; Srivastava, 1964 , 1966 , 1975 ,
1982 ; Srivastava and Bhargava, 1963 ; Johnson,
1977 ), Rozella (Johnson, 1955 , 1977 ; Howard
and Johnson, 1969 ; Ou, 1940 ; Prabhuji et al.,
2010 ) and several others.
This particular aspect has been least explored
and needs extensive studies on endophytic hyper-
parasites of the members of Oömycota.
contains animal remains. Only in certain cases,
however, sample collections have been made
mostly or exclusively from only one of the two
types of organic matter; for example, Cutter
( 1941 ) collected Aphanomyces helicoides
(= A. laevis ) and A. amphigynous from insect exu-
viae. Thus, it may be that the animal populations
of a habitat also affect the distribution pattern of
water moulds.
In studies on the distribution and abundance of
water moulds in a shallow lake of Japan, Suzuki
( 1961 ) obtained variable results and reported a
curious pattern of diurnal migration of planonts.
The number of zoospores found in samples taken
in the morning and evening of a clear day was
approximately the same at the surface, bottom
and middle region of the lake. He suggested that
the zoospores occurring in these horizontal
regions had migrated up from the bottom layers
of water. At night, the highest concentration of
water mould zoospores was in surface waters.
Samples taken on cloudy days indicated that the
motile spores (zoospores) were concentrated at
the lake surface throughout the day. During pro-
longed periods of rain, water mould propagules
were evenly distributed in the lake from surface
to the bottom. Suzuki ( 1961 ) speculated that the
oxygen level in water drove the diurnal vertical
migration of the zoospores of water moulds. He
further stated that during the summer and winter,
there was no diurnal migration of water mould
zoospores in the shallow lakes. Clausz ( 1970 )
studied a somewhat deeper lake than that explored
by Suzuki and reported a non-random distribu-
tion of water moulds. Assuming the nutrient
sources in the water to be adequate, Clausz
( 1970 ) attributed the observed vertical distribu-
tion to the infl uence of oxygen level.
The mineral content of water bodies has also
been found to affect the water mould populations
and to regulate their distribution signifi cantly.
Suzuki and Nimura ( 1961 a) reported that out of a
group of fi ve lakes, three species of water moulds -
Saprolegnia sp. (unidentifi ed), Saprolegnia diclina
and Aphanomyces sp. (unidentifi ed) - were found
only in a lake having no detectable levels of iron,
manganese, calcium, chloride or sulphate. Suzuki
and Nimura ( 1962 ) analysed the water mould
Ecological Studies
Studies of the ecology of fungi, particularly water
moulds, have been carried out with little attention
paid to the ecological aspects. The fi eld aspects
of the ecology of water moulds have lagged
behind laboratory investigations of such parame-
ters as the effects of temperature, nutrition and
pH on growth and reproduction. The emphasis
has been on laboratory analyses in the develop-
ment of knowledge of the ecology of water
moulds, with the least attention paid to the ecol-
ogy for some time. There is a vast array of work
by aquatic mycologists on the occurrence, sea-
sonal periodicity, population density and distri-
bution of water moulds in water bodies and soils
in different geographical areas of the globe using
various sampling techniques (Fig. 12.5 ).
Periodicity refers to the seasonal variation in the
occurrence of water moulds with respect to fl uc-
tuations of temperature, pH (Lounsbury 1930 ),
light, nutrients and other physico-chemical factors
in aquatic and terrestrial habitats. Attempts to
interpret or compare and contrast the various
existing reports on periodicity are limited often
by incomplete accounts of sampling and lack of
statistical analyses, among others. For example,
most reports do not mention the latitude or altitude
of the sampling sites. Nevertheless, the impor-
tance of these parameters has been established
(Prabhuji 2005 ). The debris in water, although
consisting mainly of decaying vegetation, also
 
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