Acartia tonsa production in the Patos Lagoon estuary, Brazil

Acartid copepods are abundant in estuaries, harbours, and semi-enclosed waters. A monitoring programme with the objective of evaluating copepod production, particularly that of Acartia tonsa, the dominant taxon in the Patos Lagoon estuary, was implemented. Zooplankton samples are collected monthly from two fixed locations with bongo nets 30 cm in diameter with nets of 90 and 200 mm mesh. Over a full year, 33 quantitative samples were analysed; copepods represented 40% of the organisms collected with the 90-mm mesh. Adults and copepodites of A. tonsa accounted for 19% of the total copepod fauna at both locations. Daily production rates of A. tonsa were calculated as 0.40 mg C m d for the inner estuary and 3.65 mg C m d in the channel. The value of 1 333 mg C m year calculated for A. tonsa at the channel station is very high relative to the situation in other estuaries, indicating that the estuary has a high production of copepods.