CHAPTER 27
Fish Species Biodiversity on Trawlable Bottoms of South Adriatic Basin
(Mediterranean Sea)
N. Ungaro and G. Marano
ABSTRACT
Groundfish biodiversity on trawlable bottoms of the South Adriatic basin was analysed by
means of univariate ecological indices. Raw data came from three experimental trawl surveys
carried out in the mentioned area during the summer 1996,1997 and 1998. The surveys (112
samples per survey) provided a total list of 113 groundfish species (98 teleosts, 15 selachians).
Margaleff (richness), Shannon (diversity) and Pielou (evenness) indices were estimated; the
index values per sample were mapped by kriging method, and mean values for each survey
were computed in order to detect yearly and/or spatial differences (shelf and slope zone, East
and West coast).
The global analysis of the diversity of the groundfish species on the trawlable bottoms of the
South Adriatic Sea did not show any particular trend over the triennium 1996-98, in spite of
some significant differences among the years. The main changes concern the ushelf" ecological
indices, while the "stope" situation appears to be reasonably stable; East (Albania) "shelf"values
are generally higher and more homogeneously distributed than the West shelf (Italy) ones.
Introduction
The Adriatic Sea basin is characterised by typical
geomorphologic and oceanographic features; the
bottom structure (sediments) and slope. the
water current flows and chemical-physical characteristics follow both a latitudinal (Northern,
Middle and Southern Adriatic) and a longitudinal (East and West side) gradient (Buljan and
Zore-Armanda 1979; Alfirevic 1981; Artegiani et
al. 1981). These environmental features could
affect the distribution of a large number of
species. including groundfishes.
As regards the Southern Adriatic Sea, until
1996 scientific information about diversity of
groundfish species was referred mainly to the
western side (Italian waters) (Bello and Rizzi
1988; Ungaro et al. 1996; 1998a), while data were
scarce from the eastern side (Albanian waters).
During the last years additional information
about the whole Southern Adriatic Sea came
from the European Community research project
"Mediterranean International Trawl Survey ..
(Bertrand 1996). The trawl surveys carried out
within the above mentioned project provided
new data on fish species presence and distribution in the basin; herein the collected data were
analysed by means of univariate ecological
indices in order to update groundfish biodiversity on South Adriatic trawlable bottoms during
the years 1996,1997 and 1998.
Materials and Methods
Data about groundflSh species were obtained
during three trawl-surveys carried out in South
Adriatic Sea (Mediterranean Sea), from 10 to 800
m depth (trawlable bottoms), by using a 10 mm
cod-end otter trawl net during the summer 1996,
1997 and 1998. One hundred and twelve stations
(1 haul/60 square nautical miles) were sampled
for each survey (I hour of trawling on the slope,
half an hour of trawling on the shelf) (Fig. 1). The
sampling design referring to the first survey was
random stratified (five bathymetric strata: 10-50
m, 51-100 m, 101-200 m, 201-500 m, SOl-800 m)
(Bertrand 1996) and the chosen points were resampled the following years.
Laboratorio di Biologia Marina, Molo Pizzoli (Porto), 70123 Bad, Italy
F.M. Faranda, L. Guglielmo, G. Spezie (eeLs)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag ltalia 2001
Fish Species Biodiversity on Trawlable Bottoms of South Adriatic Basin
(Mediterranean Sea)
N. Ungaro and G. Marano
ABSTRACT
Groundfish biodiversity on trawlable bottoms of the South Adriatic basin was analysed by
means of univariate ecological indices. Raw data came from three experimental trawl surveys
carried out in the mentioned area during the summer 1996,1997 and 1998. The surveys (112
samples per survey) provided a total list of 113 groundfish species (98 teleosts, 15 selachians).
Margaleff (richness), Shannon (diversity) and Pielou (evenness) indices were estimated; the
index values per sample were mapped by kriging method, and mean values for each survey
were computed in order to detect yearly and/or spatial differences (shelf and slope zone, East
and West coast).
The global analysis of the diversity of the groundfish species on the trawlable bottoms of the
South Adriatic Sea did not show any particular trend over the triennium 1996-98, in spite of
some significant differences among the years. The main changes concern the ushelf" ecological
indices, while the "stope" situation appears to be reasonably stable; East (Albania) "shelf"values
are generally higher and more homogeneously distributed than the West shelf (Italy) ones.
Introduction
The Adriatic Sea basin is characterised by typical
geomorphologic and oceanographic features; the
bottom structure (sediments) and slope. the
water current flows and chemical-physical characteristics follow both a latitudinal (Northern,
Middle and Southern Adriatic) and a longitudinal (East and West side) gradient (Buljan and
Zore-Armanda 1979; Alfirevic 1981; Artegiani et
al. 1981). These environmental features could
affect the distribution of a large number of
species. including groundfishes.
As regards the Southern Adriatic Sea, until
1996 scientific information about diversity of
groundfish species was referred mainly to the
western side (Italian waters) (Bello and Rizzi
1988; Ungaro et al. 1996; 1998a), while data were
scarce from the eastern side (Albanian waters).
During the last years additional information
about the whole Southern Adriatic Sea came
from the European Community research project
"Mediterranean International Trawl Survey ..
(Bertrand 1996). The trawl surveys carried out
within the above mentioned project provided
new data on fish species presence and distribution in the basin; herein the collected data were
analysed by means of univariate ecological
indices in order to update groundfish biodiversity on South Adriatic trawlable bottoms during
the years 1996,1997 and 1998.
Materials and Methods
Data about groundflSh species were obtained
during three trawl-surveys carried out in South
Adriatic Sea (Mediterranean Sea), from 10 to 800
m depth (trawlable bottoms), by using a 10 mm
cod-end otter trawl net during the summer 1996,
1997 and 1998. One hundred and twelve stations
(1 haul/60 square nautical miles) were sampled
for each survey (I hour of trawling on the slope,
half an hour of trawling on the shelf) (Fig. 1). The
sampling design referring to the first survey was
random stratified (five bathymetric strata: 10-50
m, 51-100 m, 101-200 m, 201-500 m, SOl-800 m)
(Bertrand 1996) and the chosen points were resampled the following years.
Laboratorio di Biologia Marina, Molo Pizzoli (Porto), 70123 Bad, Italy
F.M. Faranda, L. Guglielmo, G. Spezie (eeLs)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag ltalia 2001