International Journal of Marine Science 2014, Vol.4, No.42, 1-11
2
prokaryote-like rods suggests that the process may be
similar to that known from several types of anaerobic
protozoa (Oren, 2012).
Benthic protozoans and metazoans have been studied
in the Black Sea for more than 30 years in the
oxic/suboxic/anoxic transition zones as well as in the
permanently sulfidic and anoxic zones of the Black
Sea (Kolesnikova et al., 2014; Sergeeva, 2001, 2003a,
b; Sergeeva and Gulin, 2009; Sergeeva and Zaika,
2008; Zaika, 2008; Zaitsev et al., 1987). Meiofauna
have been found in the bottom sediments under
permanently sulfidic conditions (depth range
400~2250 m) (Sergeeva, 2001, 2003c). Later,
additional data has been obtained concerning
taxonomical richness and abundance of deep-water
protozoa and metazoa in sediments underlying
hypoxic and anoxic water column (Sergeeva et al.,
2012, 2013). This revealed that certain ciliate and
foraminifera taxa can occur in anoxic sediments and
can live in the absence of oxygen in the Black Sea (e.g.
Sergeeva et al., 2012).
Systematic studies of fauna from the deeper parts of
the Black Sea, using sediments collected with a
TV-guided multicorer (TV-MUC), began in 1994 and
2006-2010 (MEGASEEPS, HERMES and HYPOX
EU projects), where the area of the deep-water
Dnieper Canyon and the outlet area of the Istanbul
Strait‟s (Bosporus) of the Black Sea was studied in
more detail. Three oceanographic expeditions were
conducted to survey fauna in oxic/suboxic/anoxic and
permanently sulfidic sediments: RV „
Meteor’
cruise
72/2 (February–March 2007); the RV „
Arar
‟ cruise
(November 2009), RV „
Maria S. Merian
‟ cruise 15/1
(April–May 2010) (Sergeeva et al., 2012, 2013). Near
the Dnieper Canyon, discovered Nematoda (120~240
m) and Harpacticoida (120~170 m) population
included specimens of all sizes and life stages, such as
gravid females containing eggs. In the sediments
harpacticoid
Archesola typhlops
(Sars, 1920) was
found, which population included adult females,
males, and copepodites at different stages
(Kolesnikova, 2010). As well the nematode fauna was
unique and included 90 species and 9 genera unknown
from the Black Sea and 19 species, 9 genera and 1
family recognized for the first time in this basin. The
fauna included stenobiontic and eurybiontic forms
adapted to live in the redox zone (Sergeeva et al.,
2012).
During a study of bottom sediments associated with
methane gas hydrates in the Sorokin Trough (NE
Black Sea), for the first time an alive actively moving
endemic species of Cladocera was discovered in the
anoxic and sulfidic area at depths of 1990 and 2140 m.
Cladocera was described as
Pseudopenilia bathyalis
,
the type species of a new genus (Sergeeva 2003c,
2004 a) and family Pseudopenilidae (Korovchinsky &
Sergeeva, 2008).
1 Study area
In the Black Sea the combined effect of great depth (>
2000 m), restricted inflow of saline waters and large
river water input, creates a basin-wide water-column
stratification and a chemocline separating an oxic
zone above 100 to 150 m water depth from an anoxic
and sulfidic zone below. A suboxic zone exists
between the oxygenized and anoxic waters. In the
suboxic layer all oxygen is depleted and no sulfide can
be found in the water column. This layer is important
for biogeochemical and redox reactions (Codispoti et
al., 1991; Murray et al., 1989, Kuypers et al., 2003).
In the Bosporus outflow area of the Black Sea
oxygenated Mediterranean water with high density is
injected into the anoxic layers of the stratified Black
Sea water column. In the Black Sea basin oxygen is
normally absent below 150 m water depth, however in
the Bosporus outflow area, oxygen (>2 µmol/L) was
detected in warm saline water intrusions as deep as
230 m (Friedrich et al., 2013).
2 Methods
2.1 Fauna sampling
Bottom fauna was studied in the Bosporus outlet area
of the Black Sea during the RV „
Maria S. Merian
‟
cruise MSM 15/1 in April 2010 (Figure 1). This study
presents meio- and macrobenthos analyzes from 8
stations sampled along a downslope transect from
oxygenated bottom water (97.2 m) to anoxic bottom
water (295.7 m) (Figure 1, Table 1). Sediments were
sampled with a TV-guided multicorer (TV-MUC) and
with a gravity corer (GC. ITU Corer) and intact
sediment stratification was assured by visual
inspection. Sediments were sectioned in 0–1, 1–2, 2–3
and 3–4 and 4–5cm intervals and combined results
from these upper 5cm are presented. At each station
