Transcript Marine Biology

MAIN CHARACTERISTICS OF THE BIODIVERSITY
OF THE MACROFAUNA IN N. MICHANIONA BAY OF
THERMAIKOS GULF
MID-LITTORAL DISTRIBUTION OF MYTILUS
GALLOPROVINCIALIS IN THESSALONIKI BAY.
The team
• Jens Henrik Ringsbo
•Mattias von Schantz
•Harald Kellner
•Birgit Nehrwein
•Eva Mourgi
•Fotis Sgouridis
•George Anasontzis
Introduction
The main aim of the present study is to determine the
diversity of the macro fauna in the N. Michaniona Bay and
the factors that affect the biotope. In order to examine how a
community can be established in an environment
constructed by man and how biological and physical factors
interact to define the identity of the community, several
samples from different stations of the harbour have been
taken.
The subject is interesting while the result can be of
great importance when decisions are taken to change coastal
areas in the eastern Mediterranean into harbours. This is a
current subject when more and more of the coasts are
changed to correspond to the will of tourists and industries.
Materials and methods
The sample area is located on the eastern coast of
Thermaikos gulf (Nea Michaniona) in the north Aegean
Sea.
The area was chosen because of the existence of artificial
hard substrate and due to the fact that the area is not
directly affected by the outlets of the nearest urban
region (Thessaloniki 30 km). The harbour is exposed to
southern and south-western winds that are present
mostly during summertime.
The sources of organic pollution are mainly alluvial
deposits from the estuarine system of the rivers situated
on the north-western part of Thermaikos Gulf. Those
deposits are carried by the surface currents to the coasts
of N. Michaniona (Anagnostou et al. 1997, Krestenitis et
al. 1997).
The sampling took place on the hard artificial substrate of the docks
of the fishing harbour of N. Michaniona. The area is well known for
its large fishing fleet and also for different kinds of trawlers that
anchor the port. The number of fishing boats using the port is the
largest in Greece and has increased during the last years due to the
construction of a new dock. All the above induced the change of the
physiognomy of the area, as well as the increase of organic loads
from intensive fishing activities (Baxevanis,1999).
Sampling was carried out in four different stations, two of which
were located on the exposed branch of the dock (A and B) while the
other two in the inner, less exposed part, across the new harbour (C
and D). The distance between A and B stations was about 60m. D
was near the mouth of the new dock, next to anchored trawlers,
whereas C was at the sheltered corner, as it is shown in figure :
Community structures
• A and B (outer port) are almost
homogenous
• Differences between inner and outer
port
• Differences within C and D (inner
port). Sample C was taken in a corner.
Jens Henrik Ringsbo
 Samples were taken by free divers, equipped with a
quadrate of 0.25 m2 and knives.
 During the first two sampling periods (A and B
stations), 9 replicates were taken.
 The species in every replicate were sorted out
separately and identified.
 After the identification the species were stored
separately in formaline in order to be preserved
Abiotic Factors
Sample Site
Date
Temperature
Salinity
pH
A, B
30.05.00
23.9
36.4
8.1
C, D
01.06.00
22.6
36.6
8.03
The data shows that the sample sites are almost similar
concerning the abiotic factors.
As sample sites C and D were inside the harbor there is a
difference in current and wave action in comparison to the
other sample sites, which are outside the harbor.
Species number
The number of individuals within every species was counted
and put in a table.
From this table the minimum area could be calculated
(See below).
Minimum Surface Area
20
15
A
B
10
5
0
1
2
3
4
5
6
Square (50x50cm)
7 18
diagram
9
According to diagram 1 we observed that the blue curve,
station A, has a plateau at sample 4.
This plateau is probably due to bad sampling and can’t be
considered as representative result.
Furthermore, the same curve tends to make a second plateau
after the 7th replicate.
The pink curve, station B, also shows a plateau, but after the 6th
sample.
The most probable explanation is that we met a new community
during our sampling and new species entered the measurements
causing the sudden shift in both curves.
The second plateau at station A seems to be at the same level
With the plateau at station B. The decision was taken to collect
6 replicates from the sampling stations C and D.
The species from stations C and D were sorted out and identified.
All the results are summarized in the following table.
Species\Sample
Ulva sp.
Codium fragile
Codium tomentosum
Enteromorpha sp.
Padina pavonia
Punctaria latifolia
Colpomenia cinuosa
Jania rubens
Gracilaria sp.
Acetabularia mediterranea
Actinia equina
Chlamys varia
Mytilus galloprovincialis
Acanthonyx lunulatus
Carcinus mediterranus
Clibanarius erythropus
Eriphia verrucosa
Maja crispata
Pachygrapsus marmoratus
Xantho poressa
Sphaeroma serratum
Pontonia pinnophylex
Balanus sp.
Paracentrotus lividus
Columbella rustica
Monodonta sp.
Patella caruolea
Tubonilla rufa
Hermione hystrix
Pilumnus pitellis
Mercirella enigmatica
Spirorbis pagenstecheri
Eulalia sp.
Pomatoceros sp.
Stylochus sp.
Ponax trunculus
A1
x
x
A2 A3
x
x
x
x
A4 A5 A6 Sum A7
x x
x
x
x
A8 A9
x
x
B1 B2
x
B3 B4 B5 B6 Sum B7
x
x
x
x
x
x
x
B8 B9
x
x
x
x
x
x
x
x
x
x
x
x
1
1
1
2
1
1
1
1
1
1
1
1
2
4 10
2
3 x
1
4
1
1
1
x
1
1
2
4
1
0
0
0
0
1
18
0
1
5
6
0
0
1
0
1
0
1
0 x
1
0
0
0
1
1
1
2
1
1
1
1
1
1
2
1
1
2
1
1
4
1
2
5
3
1
4
2
3
1
1
1
4
3
x
1
1
1
1
1
1
1
1
1
x
x
x
1
1
0
0
0
1
1
3
2
0
0
13
0
0
3
3
4
1
0
0
2
2
0
0
0
0
1
1
1
2
6
2
4
1
4
1
1
Community Structure in different sample sites
Site A
14%
Anthozoa
2% 14%
7%
Bivalvia
2%
Gastropoda
Crustacea
Echinoidea
Polychaeta
61%
Site B
11%
3%
14%
Gastropoda
Crustacea
Echinoidea
8%
Polychaeta
Turbellaria
64%
Species\Sample
C1 C2
Ulva sp.
Codium fragile
Gracilaria sp.
x
Xantho poressa
Balanus sp.
x
Paracentrotus lividus
Phalusia sp.
Bryozoa
1
Diodora graeca
1
Ircinia sp.
x
Clavelina lepadiformis
x
Polychaeta sp.
1
Ascidia sp.
Aspidosiphon sp.
Bugula sp.
Colonia turnicate sp.
Barbatia barbata
Nereis sp.
Ostria sp.
Luria lurida
Aphroditidae
Pachygrapsus marmoratus
Pilumnus sp.
Styella sp.
Murex brutalis
1
1
Bachatia
2
Hydrozoa
x
Colpomenia sp.
Acetabularia mediterranea x
Turitella communis
2
Chlamys sp.
C3
x
C4 C5 C6 Sum D1
x
x
x
1
1
x
x
x
x
1
x
x
x
x
x
x
x
1
x
1
1
1
9
1
1
1
1
1
1
1
1
D2 D3 D4 D5 D6 Sum
x
x
x
x
x
x
x
x
1
1
2
4
x
x
x
x
x
2
2
1
2
1
4
2 x
x
x
x
x
x
1
2
1
1
4
x
x
x
x
x
1
14
7
21
x
x
1
1
1
1
5 1
2
1
10
x
1
x
11
5
1 2
3
2
13
1
x
1
2
1
1
2
1
2
1
2
2
2
x
x
1
1
3
1
18%
0%
Crustacea
Site C
Ascidiacea
3%
21%
Bivalvia
Polychaeta
6%
12% Echinoidea
Gastropoda
40%
Holothurioidea
Crustacea
Site D
Ascidiacea
6%
16%
6%
8%
Bivalvia
Polychaeta
3%
Echinoidea
Gastropoda
38%
23%
Holothurioidea
Feeding habits in site A
Feeding habits in site B
17%
45%
Grazers
Suspension
feeders
38%
23%
Carnivors
9%
68%
Feeding habits in site C
Feeding habits in site D
20%
7%
49%
33%
31%
60%
Diversity indices
Three different indices were calculated:
1. Shannon-Weaver index, one of the most commonly used
species diversity indices. The diversity index consists a
mathematical expression of the degree of participation of the
individuals of different species in a specific sampling area in
a community.
2. Evenness index represents the relationship between the
Shannon-Weaver value and the maximum mathematical
evenness possible. It expresses the stability of the
communities. It measures the distribution of individuals
among species.
3. Richness index is the total number of species..
Calculations of Shannon-Weaver, Evenness index and Richness index
1.
Shannon-Weaver: H’= -Σpi·log2 pi
where
2.
Evenness index: J’= H’/ log2 s
where
3.
pi = ni/N
Σ = sum
ni = number of individuals of i1,i2, etc
N = total number of individuals
J’= Evenness
H’= Shannon-Weaver index
s = total number of species
Richness index: The total number of species.
Shannon- Weaver Index
3.5
3
2.5
2
diversity
1.5
1
0.5
0
station A
station B
station C
stations
station D
Eveness
0.8
0.7
0.6
0.5
eveness
0.4
0.3
0.2
0.1
0
station station station station
A
B
C
D
stations
Richness
30
25
20
richness 15
10
5
0
station A
station B
station C
stations
station D
DISCUSSION
 Concerning the measurements of pH and
salinity, presented on the table, there are no
differences in the values. The temperature differences can
probably be attributed to the different weather conditions.
The first day was sunny, while the second was cloudy and it was
raining.
 The only physical parameter that can differentiate the four
stations was currents. The Stations A and B were exposed,
while the stations C and D were sheltered.
On the whole, 176 individuals were counted and classified into
taxonomic groups.As it is shown in the tables, it must be
pointed out that:
The community observed in A and B is typical for the rocky intertida
zone with Xantho poressa as leading species
 The dominant algae in A and B is Ulva sp., which is an indicator of
pollution, and therefore was expected to be found also in C and D.
However, it was almost entirely absent and probably this can be
explained by the fact that herbivores (like gastropods) were abunda
and have grazed Ulva.
 Some crustaceans are sensitive to pollution.
Considering the stations it is obvious that the number of Crustacean
increases when we go further from the main source of pollution
(31 Xantho sp. in A and B, 5 in C and D).
 In station D Polychaeta is the dominant phylum. They can be
considered as indicators of the pollution in the region.
Diversity indices
In station D diversity (Shannon-Index,H’) and evenness (J’)
have the lowest values, which means that in D community there
is a small number of dominant species and the community is
not stable.
The indices are lower in stations A and B comparing to C,
where there is a more homogeneous species composition
(highest J’).
The high values for C can be explained by the fact that the site
is placed in a sheltered corner , which offers a more stable
habitat that provides the ability to survival to many species.
Feeding behaviour
Regarding to our results about feeding habits we observe high
percentage of grazers in station C and D that probably feed on the
abundant encrusting algae. The same area is also inhabited by a lot
of suspension feeders, that benefit of the high amount of nutrients
in the water. In D where more watershed circulation is observed
the number of suspension feeders is higher. Many sponges are
observed in C and D, but not in A and B, because their larvae need
calm waters to settle.
The high amount of carnivores in sample sites A and B can either be
explained by seasonality or the fact that the smaller rocks there
provide a more suitable habitat and feeding area.
Conclusion
The different results of the 4 stations can be attributed to the
different locations of the samplings. Stations A and B were outside
the main harbor, that is why we found similar species. The factor
that probably influenced that regions was the currents.
Stations C and D were situated inside the harbor, affected by high
nutrient level due to calm water and wastes from the fishing boats,
and that’s why we found that special species composition.
Particularly, station C was at the corner of the harbor, where there
was no circulation of the water and the conditions were stable.
Station D was the nearest station to the main port.
However, the sample sites at Nea Michaniona were only visited one
time, so that many of the phenomena observed could be due to
seasonality. In addition, sampling took place only once!
MID-LITTORAL DISTRIBUTION OF MYTILUS
GALLOPROVINCIALIS IN THESSALONIKI BAY.
The team
• Jens Henrik Ringsbo
•Mattias von Schantz
•Harald Kellner
•Birgit Nehrwein
•Eva Mourgi
•Fotis Sgouridis
•George Anasontzis
Introduction
The aim of this study is to see how Mytilus galloprovincialis is
distributed in Thessaloniki bay, and how it is affected by
exposure of outlets.
Referred to other studies, benthic algae (Fuge et al., 1974;
Seeliger et al., 1977), copepods (Zafiropoulos, 1977), tunicates
(Papadopoulo, 1977), fishes (Dix, 1975, Greig, 1977) and molluscs
(Boyden, 1975; Watling, 1976 b; Pesh, 1977) have all proved
suitable for revealing heavy metal pollution.
Goldberg (1975) suggests that the Mytilus in particular could be
used for a preliminary examination, extended to all seas, of
such pollutants as heavy metals, hydrocarbons, DDT, PCBs,
and transuranic elements. (Majori, 1998)
The mussels are considered as one of the most important biological
indicators in order to study pollution in marine environment, caused
by toxic substances. This is due to the fact that they are organisms tha
are mostly sedentary and have the ability by filtering huge amounts of
sea water to bioaccumulate toxins that are found only in traces in the
marine environment (NAS, 1980, Cossa D.,1989).
Furthermore Mytilus galloprovincialis communities are found in great
abundance in Thermaikos Gulf, either in wild populations or in
aquacultures and they are of great commercial importance ( F. Bei,
V.A Catsiki & E. Galenou, 1997).
In Greece, the largest cultivated populations of the species are
found in Thermaikos Gulf (Macedonia, Northern Greece) (Jones et al
1994). Despite their great economic significance, our knowledge of the
ecology of M. galloprovincialis, regarding population abundance
(both in time and space), in the N.Aegean Sea is quite restricted and is
based mainly on Kocatas(1978), Topaloglou & Kihara(1993), Jones et
al. (1994), Pagou & Chintiroglou (1995) and Le Breton & Chintiroglou
(1998).
While it was not possible, due to lack of technical equipment,
to do analysis of heavy metals accumulated in Mytilus
galloprovincialis, we relied on the structure and composition of
its communities in the collected samples.
This was done in accordance to see how the samples resembled to
or differed from each other and how those results could be explained
taking under consideration biological and physical factors.
Moreover, we referred our collected data for the area and compared
those with those of other studies.
Material and Methods
Samples were collected at four different stations along the
coast of Thermaikos gulf and mainly in the bay of Thessaloniki.
The first sampling site was in the area of Calochori (station A).
This area can be considered to be rather polluted mainly because
of its neighboring industrial area of Thessaloniki and the nutrientrich water coming with the estuarine system of the rivers Axios,
Loudias and Aliakmonas. The chosen sampling site was in a
sheltered corner with shallow and calm water. Three samples of
the same volume were taken with the aid of a cylinder called
Corer ( 20cm diameter) from mid- littoral communities attached
on an artificial hard bottom.
The second sampling site (station B) was in the city of Thessaloniki
on a dock belonging to a yacht club. This site is certainly
influenced by urban waste and runoff from the city. Three samples
were taken in the same way from the mid- littoral zone.
The two last locations, Perea and Agia Triada, (stations C
and D) were selected because they were the only artificial substrates
with a substancial M.galloprovincialis population established on
them, and also because they were the least polluted in the bay
area (Koukouras 1979).
They were located near to a public beach and the water was
relatively clear and shallow. The same method was used and three
equal samples were collected from C. However, sampling in station D
was different. Only one big sample was collected but also two smalle
ones (using another cylinder10 cm diameter). This station was not
meant to be studied but it was added because of some difficulties
in the sorting that are described below.
The samples were then stored in plastic bags containing formalin in
order to be sorted, identified, counted and measured in length and
weight in the laboratory.
The sorting and counting of the mussels (Mytilus galloprovincialis)
was causing some problem, while they contained a lot of juveniles,
which were small and numerous.
After some discussion within the group the decision was taken to
measure a sub sample of the big sample depending on the number of
mussels.
To be able to know if this method could be acceptable the station D
was added to the study, as mentioned above.
The mean length of the mussels in the two small samples was
calculated and we found out that it was almost the same with the
mean length in the 1/16 of the big sub sample. In this way we verified
our method and the procedure continued.
DETERMINATION OF i
WHAT MEANS i ?
i is the class width, which is needed for the frequency in the
following histograms!
• Determination: i = standard deviation / 4
• Determined standard deviation: 6,1
• Resulting Class width: 1,5 mm
HISTOGRAM SITE A
35
30
25
%
20
15
10
5
.5
58
.5
55
.5
52
.5
49
.5
46
.5
43
.5
40
.5
37
.5
34
.5
31
.5
28
.5
25
.5
22
.5
19
.5
16
.5
13
5
7.
.5
5
4.
10
5
1.
0
classes
3 distinct age classes, probably March 2000, January
2000 and Autumn 1999.
No adults were observed.
The length of the mussels was measured in order to calculate the
standard deviation and average length to make it possible to put them
into length classes.
This is important while the weight could be more easily measured with
a smaller representative amount of mussels.
The weight was measured from station A and C. The reason why not all
four samples were measured was completely because of lack of time.
However, those two stations can be considered as representative
because A is a polluted area and C a rather clean one.
Three age classes could be observed. Five mussels were
taken from the youngest class (settled in March 2000) and five from the
oldest class (settled last year). The second class (January 2000) was not
measured, because it was not present in the C-sample. Thus, no
comparison between the second class of the two stations was possible.
All other species found in the cluster of mussels were also
identified and used to measure Shannon-Weaver, Evenness index
and Richness index.
Mytilus IN GENERAL
• Size: normally between 5 and 8 cm, max. 15 cm
Pic.1: Mytilus sp. (www.aldebaran.org
/impressionen/miesmuschel.htm)
• Live in colonies and are attached with strong byssus threads
• Important cleaner of the costal water, one individual can filter ca. 3 l/h
• Feed Plankton
• Found in southern and northern hemisphere
• Rapid growth in Mediterranean Sea (up to 50 mm / in the 1. Year)
• Commercial production (Greece ca. 30000 t/year)
• Important indicator species
Physical factors
Sampling station
Temperature o C
Salinity % o
pH
A
B
24.2
19
8.1
22.4
35.7
8.02
C
24.6
35.1
8.06
COMPARISON BETWEEN 20CM CYLINDER (D) AND 10CM CYLINDER
(Dsub)
mm
average length
7.9
7.8
7.7
7.6
7.5
7.4
7.3
7.2
7.1
average
length
D
Dsub1
Dsub2
COMPARISON OF THE SITES IN NUMBER AND LENGTH
100000
10000
number
1000
100
average
length
[mm]
10
1
A
B
C
D
The density in site A is lower than in other sites.
Site B, C, and D have a lot of juveniles of the first age class
compared with A, visible on the smaller average of length.
55
.5
51
46
.5
42
37
.5
33
28
.5
24
19
.5
15
10
.5
6
5
35
30
25
20
15
10
5
0
1.
%
HISTOGRAM SITE A
classes
3 distinct age classes, probably March 2000, January
2000 and Autumn 1999.
No adults were observed.
5
classes
55
.5
51
46
.5
42
37
.5
33
28
.5
24
19
.5
15
10
.5
6
1.
%
HISTOGRAM SITE B
35
30
25
20
15
10
5
0
5
classes
55
.5
51
46
.5
42
37
.5
33
28
.5
24
19
.5
15
10
.5
6
1.
%
HISTOGRAM SITE C
25
20
15
10
5
0
classes
55
.5
51
46
.5
42
37
.5
33
28
.5
24
19
.5
15
10
.5
6
5
40
35
30
25
20
15
10
5
0
1.
%
HISTOGRAM SITE D
RESULTS OF THE DEMOGRAPHIC
HISTOGRAMS
Adults were only observed in sample site D.
B, C and D were characterized by high percentages of juvenile
mussel of the first age class.
Site A shows distinct age classes compared to the others.
HYPOTHESIS
Pic.3: Mytilus sp.
(www.biology.ucsc.edu/classes/bio161
l/Images/Animals/a30myt.html)
Referred to our results, we expect that the main
reproduction probably takes place outside the
Thessaloniki Bay.
The main recruitment of the different sample sites is
strongly affected by the current (counter-clockwise)
within the Thessaloniki Bay.
Pic.2 NASA
Main current in the Thessaloniki Bay causes
differences in the larvae distribution (space and time).
Body / Shell Ratio Diagram
3.5
Bodyweight [g]
3
C
2.5
y = 1.3355x - 0.0219
c = 0.8
2
A
y = 1.154x - 0.0786
c = 0.93
1.5
Linear
(C)
1
0.5
Linear
(A)
0
0
1
2
Shellweight [g]
3
WEIGHT
Measure of the weight of
different size classes
(juvenile, 30 mm class).
RESULT
Pic.4: Mytilus sp. (web.mit.edu/corrina/tpool/cmussel.html)
Mytilus at site A have more shell weight than on site
C.
The fresh body weight is almost the same on both
sites.
SHANNON- WEAVER INDEX
2.5
2
1.5
1
0.5
0
A
B
C
Sample sites
D
RICHNESS
10
8
6
4
2
0
A
B
C
Sample sites
D
EVENESS [%]
100
80
60
40
20
0
A
B
C
Sample sites
D
Discussion
The low salinity at sampling station A is caused by the
freshwater runoff from the estuarine system of the rivers
Axios, Loudias and Aliakmon.
According to our observations regarding the average number of
individuals and the average length of them in the four different stations,
station A has the lowest number of individuals but the highest average
length. That means that in A we don’t have so many small juveniles as we
do in B and C and that increases the average length. This can be explained
by the fact that in A the water is shallow and there is intense space
competition and predation stress. Probably, natural selection forces the
mussels to have a rapid growth.
Ebling et al. (1964) mentioned in their experiment that crabs
have selective tendency for the size of mussel, for example
Carcinus maenus attacks only the juveniles. Many crabs, of
different sizes, crawl about in or around the mussel beds and
were observed to break open small mussels. There is no doubt
that predation by crabs plays an important in the life of young
mussels at any observed station (Hosomi, 1980).
Due to this crab predation, it could be assumed that the
high growth rate of the shell is attributed to an adaptation of
the mussels to construct a strong and resistant shell.
However, the growth of the flesh is normal. That means that
the mussel does not grow faster. It just dedicates more energy
in constructing the shell to face the natural stress from the
environment.
Another effect of predation is the creation of open space for
the invasion of new species. This could explains the relatively
high richness of the station A.
The main reproductive population of mussels exists in
the wider area of Perea (personal comm. With Prof.
Chindiroglou). The currents entering the Gulf from the east
helps the diffusion of the mussel larvae. Most of them attach
on several hard substrates during their transportation. Thus,
only some of them reach the west part of Thermaikos Gulf,
where Kalochori, Station A, is located.
The above hypothesis is contributed by the fact that many
juveniles are found at the Eastern part of the Gulf. These are
getting smaller as further West we go, because of the time
they need to travel. In addition, larvae usually settle near the
surface of water, where they can easily be predated.
So, at station A, we can observe juveniles from the last
three reproduction periods of the source area ( i.e.Perea).
Concluding, we could say that even if we have found
larger juveniles in station A, they unfortunately wont have
the possibility to grow and reproduce due to the fact that
pollution stress them in different ways. The stations B and C
have relatively deeper waters that allow the movement of the
larger individuals to deeper places of their community so that
they can avoid predation and have the chance to reproduce.
Finally the other species found in A are important
indicators of a polluted environment.
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ACKNOWLEDGEMENTS
 To Prof. Chintiroglou for his advice and equippement.
 To Prof. Bedulli for his help during the sampling
 To Prof. Daguzan for his usefull directions