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International Journal of Marine Science 2013, Vol.3, No.43, 352-360
http://ijms.sophiapublisher.com
355
On some distance from the site of erosion along the
coastline in both directions, where the concentration
of particles decreased, there are rocks on the vertical
parts of these the young of the year
Mytilus
and
Mytilaster
presented, but not adult animals. The
horizontal parts of rocks were covered by a narrow
gel-like layer without macroorganisms and microalgae.
On a single rock, we observed one of its sides was
influenced by waters with an increased concentration
of mineral particles, and the other was not exposed to
their influence. On the unexposed side there were
more mussels and they were bigger. Species diversity
of epibiontic Hydrozoa polyps on mussels and polyp
abundance were higher on the unexposed side
(Shadrin and Grishicheva, 1999). On the exposed side
there were no polyp species with open thecae.
The increased concentration of mineral particles,
especially hydrophilic ones, is a threat not only to
benthic organisms, but also to planktonic copepods – a
ration, somatic and generative production were
significantly reduced. Results show that species
diversity and total biological production in the studied
coastal area were drastically decreased. It is known
that fine mineral particles can have a dramatic
physical effect on aquatic organisms – they may clog
the breathing apparatus (i.e., gills) of fishes and
invertebrates, inhibit proper respiratory function in
eggs and larvae (suffocation), alter substrates, and
bury benthic organisms (Brennan and Culverwell,
2004). Fishes, which caught in the sea near the
Vasiljev Ravine, had an abundance of mineral
particles in their gills.
2.2 Artificial beaches
Similar results when an increased concentration of
non-toxic small mineral particles from coastline
erosion impacted on marine communities were
observed by us in other places of the Crimean
coastline. Creation of the artificial beaches from
limestone gravel may also lead to same results (case
of near Karadag area is an example). An artificial
increase of limestone gravel in the beach sediments
leads to an increase of turbidity of the water in the sea
and degradation of mussel settlements (Klyukin,
2004), because the waves grind down of the limestone
gravel of 8% per year (Zhdanov, 1958). As usual an
effect of an increase of non-toxic mineral particle in
sea water was underestimated making the environmental
assessments of a human impact on marine biota. A
construction of the artificial beaches with a use of
limestone gravel may lead to the negative effects on
marine biodiversity, which similar to ones from
coastline erosion.
2.3 The Bakalskaya Spit case
Bakalskaya sand spit (45°47' N; 33°10' E) having
formed through merging of two accumulative spits,
now stretches along the northwestern coast of the
Crimea (Karkinit Gulf) (Zenkovich, 1960; Goryachkin
et al., 2012; Shadrin et al., 2012). The 5-km long
western causeway adjoins the shore ledge of Kudash
and extends northward. During the southern and
southwestern storms the sea waves roll over the
embankment and enter into the lagoon-lake (lying
between the spits). To analyze the causes and
consequences of degradation of beaches and Bivalve
settlements in the sea we conducted the long-term
study (2000-2013) here. Some results were published
previously (Shadrin et al., 2012). A loss of sand from
both spits (much more from west one) - with rate of
the shoreline retreat about 5-10 m per year and more
was observed. Analysis of long-term satellite data of
U.S. Geological Survey (
http://landsatlook.usgs.gov/
)
reflected similar results - during the period from 2001
to 2011 the west spit became narrow and moved into
the lake 100-200 m. This 12-year long study shows us
that this process is due to many reasons both
natural/climatic and anthropogenic origin. The
interrelationship of climate change and increasing
anthropogenic pressure in the degradation of
Bakalskaya Spit was analyzed previously (Shadrin et
al., 2012). It was shown that human pressure also
contributes to the accelerated degradation of the spit,
primarily through the spit de-vegetation. De-vegetation
increases the loss of sand from beaches due to high
acceleration of wind and water erosion. Smallest
sediment particles are moved by wind from
de-vegetated dunes and beaches. So de-vegetation of
the spit and its subsequent erosion has resulted in a
significant increase of the sand flow from the spit into
the sea and the lake. The decreased beach – sand spit
area, which acts as natural mechanism of prevention
of cliff erosion, leads to increasing of erosion of
clayey cliffs near the spit; a flux of clayey particles
into the sea grows; more these particles sediment on
sand bottom. Water turbidity also increases.