The Black Sea
445
Eutrophication and/or pollution are probably also the cause for the
conspicuous decline of the marine phanerogams Zostera marina and Z.
noltii, the latter being the predominant seagrass in Romanian waters
(Bacescu et al. 1971). They have disappeared in 95% of the so-called
enclaves (the term "enclave" is used by most Romanian researchers only
for these marine phanerogams because both species have never formed
large, compact fields as typical for the Ukrainian as well as for the
Bulgarian coasts). Nowadays, along the Romanian coast between Cape
Midia and Varna Veche, only few individual plants of Zostera marina can
be found off Tuzla. Zostera noltii occurs only in small "clusters" of
maximal 5 -10 m 2 each, at 1-2 m depth off Tuzla and Varna Veche.
19.3.2 The Phyllophora Fields
An important element of the benthic vegetation of the Black Sea is the
algal biomass pertaining to the genus Phyllophora, particularly in the
so-called Phyllophora field, which later on became known under the
name "Zernov's Field". The "field" is located in the sea area northeast of
the Danube delta which is characterized by its very high productivity. It
extends to a depth of 30 to 50 m, covers an area of more than 10 900
km 2 , and is surrounded by a circular current (Fig.19.1). The first quantitative evaluation of the Phyllophora biomass approached 10 million tons
wet weight (Kalughina-Gutnik 1975; Kaminer 1978). Since the beginning
of the 1940s, these algae have been utilized by an agar-producing industry centered in Odessa. The biomass of the three species Phyllophora
nervosa, P. brodiaei and P. pseudoceranoides exceeded by far all the other
forms of marine macrovegetation, either seaweeds or spermatophytes, in
the Pontic Basin (Vasiliu and Bodeanu 1972).
In 1960-1965, when ecological conditions were still considered normal by Russian experts, the stock of Phyllophora was estimated as not
more than 5.5 million tons wet weight. We assume that the surprising
difference between these two estimates is due either to an overestimation
by Kalughina-Gutnik and by Kaminer or the result of uncontrolled
overexploitation of the algal stock during years between the 1940s and
1960. In 1978 Kaminer estimated the Phyllophora biomass in the "Field"
at 1.5 to 2.5 million tons wet weight.
Although there may be many causes for this alarming decline (cf.
Table 19.3), we believe that eutrophication has played a major role. An
indirect effect of eutrophication is possibly the deterioration of the light
intensity due to the enormous increase in phytoplankton biomass from
about 500 to 12 000 mg m 3 during the past three decades (Table 19.4).
445
Eutrophication and/or pollution are probably also the cause for the
conspicuous decline of the marine phanerogams Zostera marina and Z.
noltii, the latter being the predominant seagrass in Romanian waters
(Bacescu et al. 1971). They have disappeared in 95% of the so-called
enclaves (the term "enclave" is used by most Romanian researchers only
for these marine phanerogams because both species have never formed
large, compact fields as typical for the Ukrainian as well as for the
Bulgarian coasts). Nowadays, along the Romanian coast between Cape
Midia and Varna Veche, only few individual plants of Zostera marina can
be found off Tuzla. Zostera noltii occurs only in small "clusters" of
maximal 5 -10 m 2 each, at 1-2 m depth off Tuzla and Varna Veche.
19.3.2 The Phyllophora Fields
An important element of the benthic vegetation of the Black Sea is the
algal biomass pertaining to the genus Phyllophora, particularly in the
so-called Phyllophora field, which later on became known under the
name "Zernov's Field". The "field" is located in the sea area northeast of
the Danube delta which is characterized by its very high productivity. It
extends to a depth of 30 to 50 m, covers an area of more than 10 900
km 2 , and is surrounded by a circular current (Fig.19.1). The first quantitative evaluation of the Phyllophora biomass approached 10 million tons
wet weight (Kalughina-Gutnik 1975; Kaminer 1978). Since the beginning
of the 1940s, these algae have been utilized by an agar-producing industry centered in Odessa. The biomass of the three species Phyllophora
nervosa, P. brodiaei and P. pseudoceranoides exceeded by far all the other
forms of marine macrovegetation, either seaweeds or spermatophytes, in
the Pontic Basin (Vasiliu and Bodeanu 1972).
In 1960-1965, when ecological conditions were still considered normal by Russian experts, the stock of Phyllophora was estimated as not
more than 5.5 million tons wet weight. We assume that the surprising
difference between these two estimates is due either to an overestimation
by Kalughina-Gutnik and by Kaminer or the result of uncontrolled
overexploitation of the algal stock during years between the 1940s and
1960. In 1978 Kaminer estimated the Phyllophora biomass in the "Field"
at 1.5 to 2.5 million tons wet weight.
Although there may be many causes for this alarming decline (cf.
Table 19.3), we believe that eutrophication has played a major role. An
indirect effect of eutrophication is possibly the deterioration of the light
intensity due to the enormous increase in phytoplankton biomass from
about 500 to 12 000 mg m 3 during the past three decades (Table 19.4).