Preprint volume - SIBM

Pre-print Volume – Posters
PLANKTON COMMITEE
G. BOTTINELLI, T. DI FESTA, A.M. PASTORELLI, N. UNGARO, M.R. VADRUCCI *
ARPA Puglia – Regional Agency for the Environmental Protection and Prevention, Dipartimento Provinciale di
Bari, Via Oberdan, 18 - 70126 Bari, Italia.
a.pastorelli@arpa.puglia.it
* ARPA Puglia, Dipartimento Provinciale di Lecce, Via Miglietta, 2 - 73100 Lecce, Italia.
NUMERICAL ABUNDANCE AND NUMBER OF TAXA
IN PHYTOPLANKTON SAMPLES: PRELIMINARY COMPARISON
BETWEEN TWO DIFFERENT COUNTING STRATEGIES
DETERMINAZIONE DELLA DENSITÀ CELLULARE E DEL NUMERO DI TAXA
IN CAMPIONI DI FITOPLANCTON: CONFRONTO PRELIMINARE
TRA DUE STRATEGIE DI CONTEGGIO
Abstract – The comparison between two different counting procedures for the analysis of phytoplankton
samples was reported in this study. The comparison was made on 10 seawaters samples, collected monthly
from October 2009 to December 2009 in the marine coastal waters of the Apulia region (southern Italy).
The samples were analyzed according to the Utermöhl’s method using two counting procedures of the
sedimentation chambers: counting random field and counting sectors. The results showed significant
differences between the two counting procedures.
Key-words: phytoplankton, counting procedures, Mediterranean Sea, Adriatic Sea, Ionian Sea.
Introduction – Phytoplankton is one of the Biological Element considered suitable for
the assessment of the environmental status of marine coastal waters, as it was stated by
the Water Framework Directive (EC/2000/60) and other National Acts. As a
consequence, the monitoring of phytoplankton guilds (abundance and composition) is
currently carried out by the Regional Agency for the Environmental Protection and
Prevention (ARPA) along the Apulia marine coastal areas. Phytoplankton guilds were
analyzed following the Utermöhl’s method (1958), currently certified by UNI-EN
15204 (2006). In this study, preliminary results about the statistical comparison
between two different counting procedures are reported.
Materials and methods – Seawater samples were collected monthly from October
2009 to December 2009 in 7 stations, 5 located along the Adriatic coast (Ofanto river
mouth, Bari, Monopoli, San Cataldo and Alimini lagoon mouth) and two along the
coast of the Ionian Sea (Porto Cesareo and Ugento). Seawater samples were collected
by means of a Niskin bottle in the sub-surface layer (0.5 m), kept in PET dark bottles,
fixed with Lugol's solution and analyzed within one month from the sampling. The
comparison of the two counting procedures was carried out only on 10 seawater
samples collected for phytoplankton analysis. After cell settlement, in 25 ml or 10 ml
sedimentation chambers, each sample was counted by means of two different counting
procedures envisaged by the Utermölh’s method: 1) counting on random fields; 2)
counting on portions of the sedimentation chambers (sectors).
For the former counting procedure, a number of random fields were counted until a
total of 400 cells were reached (corresponding to 5-10% accuracy). On the contrary,
the second counting procedure is a modification of counting the whole chamber
procedure, considered more appropriate for water samples with low phytoplankton
densities (EN 15204). The whole sedimentation chamber was divided into 8 sectors.
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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