Biol. Mar. Medit. (2006), 13 (1): 242-245
M. Giacomini, G. Alabiso*
Dipartimento di Informatica Sistemistica e Telematica, Università di Genova,
Via Opera Pia, 13 - 16145 Genova, Italia.
*CNR-IAMC Talassografico “A. Cerruti”, Via Roma, 3 - 74100 Taranto, Italia.
[email protected]
TEMPERATURE STUDY IN THE MAR PICCOLO OF TARANTO
(ITALY, MEDITERRANEAN SEA)
STUDIO DELLA TEMPERATURA NEL MAR PICCOLO DI TARANTO
(ITALIA, MAR MEDITERRANEO)
Abstract
In the present paper, the following historical series of temperature data from a station located in the
Primo Seno of the Mar Piccolo basin were analysed: 1919-1923, 1932-1934, 1962-1969 and 1996-2004.
The statistical analysis results showed a clear trend to seawater temperature increase although the available
data series does not permit to exactly quantify such increase. The increase was in accordance with the warming observed in the Mediterranean and let the settlement in the basin of several warm-water species.
Key-words: climatic changes, time series, Mar Piccolo of Taranto, Mediterranean Sea, temperature.
Introduction
The aim of the present paper is to detect a possible temperature increasing
trend in the Mar Piccolo basin (Taranto) in accordance to what observed in the
western Mediterranean where a significant increase in the average temperature
was registered (Bethoux et al., 1990). In fact, the increasing rate of global climate
change observed in the last century is predicted to accelerate in the present one by
the end of which temperature is expected to rise 1-3.5 °C (Watson et al., 1996).
It is well known that climatic fluctuations strongly affect the marine biota
(Bianchi, 1997) and there are evidence that some observed biodiversity changes
in the Mediterranean Sea are related to increasing seawater temperature (Bianchi
and Morri, 1993, 2000; Bombace, 2001; Cecere and Petrocelli, 2004). Therefore,
the study of temperature trend is important to better understand the marine communities changes and, sometimes, to predict such changes. In particular, enclosed
coastal basins, like the Mar Piccolo, are more subject to temperature increase the
effects of which can be enhanced by the confinement.
To this purpose, in a previous paper (Alabiso et al., 2005), a short historical
series of temperature data (from 1996 to 2003) was analysed. The yearly trends
obtained pointed out a not certain positive trend (r2=0.74) supported, however, by
the power increase of the continuous component of temperature signal calculated
by means of the coefficients of Fourier. Since the yearly calculated increase was
about 0.18 °C, which is usually considered a very high increase, it was decided to
analyse the historical data series, even though not continuous, in possession of
the Institute of Coastal Marine Environment of Taranto to verify if the increasing trend is detectable also over a longer period.
Temperature study in the Mar Piccolo of Taranto
243
Materials and methods
The historical series of the temperature values analysed come from a station
(lat. 40°28’47” N, long. 17°15’38” E) located in the Primo Seno of the Mar Piccolo basin in the following periods: 1919-1923 (Cerruti, 1925), 1932-1934 (Cerruti,
1938), 1962-1969 (Vatova, 1972) and 1996-2004 (present paper). A non parametric
test (χ2) was performed on raw data to single out significative variations of each
monthly mean. Successively, on the raw data series, a mobile mean was calculated,
by a linear model, to obtain 12 parameters for those years more represented in
the measures (23 in all), so eliminating every variation due to seasonality. On this
group, consisting of 12 parameters for each year, the ANOVA was carried out followed by the algorithm of Duncan test to single out years homogeneous groups.
(a)
35
35
30
30
30
25
25
25
20
20
T (°C)
35
T (°C)
T (°C)
Results
Fig. 1 (a, b, c, d) shows the trends of the temperature values in the four considered periods. χ2 analysis pointed out that the various years are not significative
20
15
15
10
10
10
5
5
5
12- 12- 12- 12- 1212- 12- 12- 121918 1919 1920 1921 1922 (b) 1931 1932 1933 1934 (c)
15
1212121212121212121961 1962 1963 1964 1965 1966 1967 1968 1969
35
30
T (°C)
25
20
15
10
5
(d)
121212121212121212121995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Fig. 1 - Temperature raw data in the four considered periods.
Dati grezzi di temperatura nei quattro periodi considerati.
Fig. 1 – Temperature raw data in the four considered periods.
Dati grezzi di temperatura nei quattro periodi considerati.
different; only 5 months out 300 are significatively different from the expected
mean value. Such months were the following: December 1922, February 1934,
December 2001 (with a decreasing mean monthly value) and November 2001,
June 2003 (with an increasing mean monthly value). The calculation of the yearly
tendencies did not show specific linear trends (both slopes and r2 values being
close to 0). The cluster analysis results are reported in Fig. 2, where both years
homogeneous groups and the temperature mean value of each year are marked.
244
M. Giacomini, G. Alabiso
1996 1932 1934 1919 1962 1933 1965 1966 1967 1968 1964 1963 1997 1998 1920 1999 2000 1922 1921 2001 2002 2004 2003
18.9 18.9 19.0
18.7 18.9
18.4 18.5 18.5 18.6 18.6 18.7
18.3 18.4 18.5 18.5 18.6 18.6
18.1 18.3 18.4
18.0 18.1 18.1 18.3
17.8 17.9 17.9 17.9 18.0 18.1 18.1
17.7 17.8 17.9 17.9 17.9 18.0
17.6 17.6 17.6 17.7 17.8 17.9
17.3 17.3
Fig. 2 - Cluster
analysis
the numbers
are of
thetemperature.
yearly means of
Fig. 2 – Cluster
analysis
results:results:
the numbers
reported inreported
the clustersinarethe
theclusters
yearly means
temperature.
Risultati
della cluster analysis: i numeri riportati nei cluster sono le medie annuali della temperatura.
Risultati della cluster analysis: i numeri riportati nei cluster sono le medie annuali della temperatura.
Conclusions
Examining the groups of years with similar characteristics, a some uniformity
among contiguous years is detectable with the exception of the years 1920, 1921
and 1922 which are similar to those of the period 1996-2004, and the year 1996
which is similar to the period 1932-1934. Moreover, it is also clear that the recent
years, except 1996, are comprised in the clusters where the highest mean values
fall. Therefore, it is possible to conclude that, in the Mar Piccolo of Taranto, the
trend to temperature increase is confirmed although the available data series does
not permit to exactly quantify such increase.
The observed temperature increase is confirmed by the presence in the Mar
Piccolo of numerous warm-water non-indigenous species, many of which are lessepsian migrants, which are spreading throughout the basin (Carriglio et al., 2004;
Cecere et al., 2004, 2005; Mastrototaro et al., 2004a, 2004b). In particular, it
just seems that, in the Mar Piccolo, only the species with a tropical affinity - i.e.
the macroalgae Caulerpa racemosa Forsskål (J. Agardh) var. cylindracea (Sonder)
Verlaque, Huisman et Boudouresque and Hypnea cornuta (Kützing) J. Agardh
and the ascidian Microcosmus squamiger Michaelsen, 1927 - are well adapted to
the environmental conditions, as also showed by ecophysiological studies (Petrocelli and Cecere, 2006) and are becoming invasive (Cecere and Petrocelli, 2004;
Mastrototaro et al., 2004a). On the contrary, the cold-temperate water species,
even though usually reported as invasive, did not behave in such a way (Cecere
and Petrocelli, 2004).
In the light of these considerations, to know the temperature trend of a particular zone could permit to predict the destiny of an introduced species on the
basis of both its biogeographic element and affinity to temperature.
References
ALABISO G., GIACOMINI M., MILILLO M., RICCI P. (2005) - The Taranto sea system: 8
years of chemical–physical measurements. Biol. Mar. Medit., 12 (1): 269-373.
BETHOUX J.P., GENTILI B., RAUNET J., TAILLIZ D. (1990) – Warming trend in the western Mediterranean deep water. Nature, 347: 660-662.
BIANCHI C.N. (1997) – Climate change and biological response in the marine benthos. Atti 12°
Congresso dell’Associazione Italiana di Oceanografia e Limnologia, M. Picazzo Ed., Genova,
1: 3-20.
Temperature study in the Mar Piccolo of Taranto
245
BIANCHI C.N., MORRI C. (1993) – Range extension of warm-water species in the northern
Mediterranean: evidence for climatic fluctuations? Porcupine Newsletter, 5 (7):156-159.
BIANCHI C.N., MORRI C. (2000) – Marine biodiversity of the Mediterranean Sea: situation,
problems and prospects for future research. Mar. Pollut. Bull., 40 (5): 367-376.
BOMBACE G. (2001) – Influence of climatic changes on stocks, fish species and marine ecosystems in the Mediterranean sea. Archo Oceanogr. Limnol., 22: 67-72.
CARRIGLIO D., FANELLI G., RUBINO F. (2004) – First record of the alien gasteropod
Melibe fimbriata (Opistobranchia: Tethydae) in the Taranto seas (Mediterranean Sea). J.
Mar. Biol. Ass. U.K., 84 (5): 1067-1068.
CECERE E., PETROCELLI A. (2004) - Floristic and biogeographic considerations about the
benthic macroalgal flora in the Gulf of Taranto. Biogeographia, 25: 7-18.
CECERE E., PETROCELLI A., VERLAQUE M. (2004) – Morphology and vegetative reproduction of the introduced species Hypnea cornuta (Rhodophyta, Gigartinales) in the Mar
Piccolo of Taranto (Italy, Mediterranean Sea). Bot. Mar., 47: 381-388.
CECERE E., RUBINO F., FANELLI G., SARACINO O.D., PETROCELLI A. (2005) - Individuazione e monitoraggio di specie alloctone nei mari di Taranto. CNR, IAMC Ed.,Taranto.
StampaSud, Mottola (TA): 20 pp.
CERRUTI A. (1925) – Il Mar Piccolo ed il Mar Grande di Taranto. I Parte. Preliminari Oceanografici. Ministero dell’Economia Nazionale. Ispettorato Generale della Pesca. Provveditorato Generale dello Stato, Roma: 120 pp.
CERRUTI A. (1938) – Ricerche oceanografiche compiute nel Mar Piccolo, nel Mar Grande e
nel Golfo di Taranto durante il triennio 1932-34. Atti R. Acc. Sc. Napoli, 1, Serie 3a, N. 2:
169 pp.
MASTROTARO F., PETROCELLI A., CECERE E., MATARRESE A. (2004a) – Non-indigenous species settle down in the Taranto Seas. Biogeographia, 25: 47-54.
MASTROTARO F., PANETTA P., D’ONGHIA G. (2004b) - Further records of Melibe viridis
(Mollusca, Nudibranca) in the Mediterranean Sea, with observations on the spawning. Vie
et Milieu, 54 (4): 251-253.
PETROCELLI A., CECERE E. (2006) – Photosynthetic activity of the introduced seaweed
Hypnea cornuta (Gigartinales, Rhodophyta) in the Mar Piccolo of Taranto: preliminary
results. Biol. Mar. Medit., 13 (1): 745-747.
VATOVA A. (1972) - Osservazioni fisico-chimiche periodiche nel Mar Grande e Mar Piccolo di
Taranto (1962-1969). Boll. Pesca Pisc. Idrob., 27 (1) (N.S.): 43-79.
WATSON R.T., ZINYOWERA M.C., MOSS R.H. (1996) – Climate change 1995. Impacts,
adaptations and mitigation of climate change: scientific-technical analysis. Contribution of
working group II to the Second Assessment Report of the Intergovernmental Panel on Climate
Change, Cambridge University Press, NY: 878.