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Ciclo anual del Copépodo Acartia tonsa Dana 1849 en la zona interna de la Bahía Blanca (Provincia de Buenos Aires, Argentina)
Maria Elena Sabatini

ANNUAL CYCLE OF THE COPEPOD Acartia tonsa DANA IN THE INNERMOST PART OF THE BAHIA BLANCA (PROVINCE OF BUENOS AIRES, ARGENTINA-). The annual cycle of the copepod Acartia tonsa (Calanoida) was studied in the innermost part of the Bahia Blanca. The abundance of adults and larval stages was estimated fortnightly and for each sampling date thirty female and ten males adults were measured. The total population showed two peaks of abundance: one was noticed at the beginning of spring and the other, with greater numbers, throughout summer. The presence of this species was continuous throughout the whole period studied. and apparently reproduction occurred all through the year. though it was less intense during the cold months. Finally, Acartia tonsa can produce "dormant eggs" as a strategy to maintain its population during periods of low temperature. At least seven generations developed during the year. The duration of each generation ranged from four to seven weeks. The correlation coefficients between adult body size and temperature and chlorophyll a concentration at the time of sampling were weak, or no relations was evident, compared with those calculated when temperature and average amount of food during the month preceding the sampling date were taken into consideration. Temperature seems more important than food availability for the determination of adult length. The relationship between sex ratio variations and population density fluctuations during the annual cycle can be attributed to a possible homeostatic effect of the sex ratio on population abundance.

Keywords: Copepoda, Acartia tonsa, annual cycle, Blanca Bay.
Contents of this volume Sci. Mar. 53(4) : 847-856 Back PDF
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