Preprint volume - SIBM

Pre-print Volume - Oral presentations
Topic 2: MARINE ORGANISMS AND ECOSYSTEMS AS MODEL SYSTEMS
Our objective is to present the first data which support the hypothesis of the warm
climate trend driven range extension of E. punctata, describing its potential as a
practical indicator of Mediterranean Sea climate variability and tropicalization.
Materials and methods – Records of E. punctata have been collected for a few years
and organized in a database. Both data from literature and public and private
collections were considered. The database contains 145 lots from the Italian coastline,
representing 5982 specimens (but abundant populations were often greatly
underestimated). Unfortunately, data derive from the occasional sampling effort of
researchers and collectors and not from a planned monitoring. Therefore, it is possible
that the discovery of new stations of E. punctata happened later than its real
colonization. However, since the Italian coastline was searched for shells by private
collectors with great intensity in the last decades, especially in the northernmost
stations of Campania and Lazio, we suppose this bias does not affect our understanding
of the phenomenon. A synthesis of the records along the Italian Tyrrhenian coastline is
given in Tab. 1.
Tab. 1 – First records of Echinolittorina punctata along a latitudinal transect from southern Sicilia to
the Tyrrhenian Sea coastline.
Prime segnalazioni di Echinolittorina punctata lungo un transetto latitudinale dalla Sicilia
meridionale alla costa del Mar Tirreno.
Locality Latitude N First records
Agrigento 37.3 Mid 20 th century
Catania 37.4 Mid 20 th century
Messina 38.3 Late 20 th century
Vibo Valentia 38.7 1997
Napoli 40.8 2004
Fiumicino 41.8 2007
Sea Surface Temperature data comes from re-analysis dataset which combines in
optimal way model and observations in order to obtain the most accurate estimates on
regular spatial and temporal grid. The model has an horizontal resolution of about 6,5
km and 72 unevenly spaced vertical levels. The dataset contains the most important
physical features of the ocean circulation (i.e. temperature, salinity, current velocities,
etc).
A first qualitative correlation between distributional and temperature data was looked
for through the analysis of the temporal temperature series of the March mean sea
surface temperature. March was chosen since it is the very beginning of the
reproductive cycle and therefore supposed to be the key month in the process. The
mean SST in March in Agrigento was selected as a reference temperature for all
stations, since in Agrigento the species has always been recorded in the analyzed time
frame (1985-2007). This temperature was considered the minimum temperature needed
for the reproduction of the species and then superimposed on the SST graph of other
stations to see to which extent temperatures were above this level and how the presence
of E. punctata could be correlated.
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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