COMPARISON OF SPATIAL LARGE SCALE SAMPLING SYSTEMS FOR COPEPODS IN THE PASSAGE DRAKE

THOMPSON GUSTAVO; DINOFRIO ESTELA; ALDER VIVIANA

Buenos Aires

Conferencia; Scientific Committee on Antarctic Research XXXI - Open Science Conference; 2010

Scientific Committee on Antarctic Research

Features of three large spatial scale (approx. 5 nautical miles/sample) sampling systems and the results get for copepods in the Drake Passage sector were compared: i) A pump-net system designed and mounted on an icebreaker which performed a non continuous sampling during April 2000 and 2001, ii) A Continuous Plankton Recording (CPR) Type I used in April, 1926 (Hardy 1936) and iii) CPR Type II in February 2000 (Takahashi et al., 2010). Pump-net system with 20 ìm mesh-net registered up to 3515 and 2791 copepods/sample in 2000 and 2001 respectively, in which 66% (range 34-93%) were larvae nauplii and 26% (range 7-54%) were Oithona similis and Microsetella norvergica. CPR Type I (approx. 423 ìm silk mesh) recorded up to 250 copepods/segment of silk mesh and CPR Type II (270 ìm silk mesh) recorded dominance of copepods with 121 ± 201 zooplankton specimens/segment with a maximum of 1537 ind. /section, in these samples only 1% were copepod nauplii larvae and 26% were Oithona similis. Without considering nauplii larvae, both total number of specimens of copepods by sample (537 ± 386 copepods/sample) and the relative contribution of Oithona similis (average: 77% range 55-99%) got with the pump-net system were higher than the corresponding values registered with CPR Type II. Although pump-net system was not autonomous, it allows estimating absolute abundances and it has the advantage of solving two CPR problems; clogging of the mesh and catching efficiency of nauplii larvae and small species of copepods. As a result, the use of both instruments together would allow calibrate and complement the CPR results.Oithona similis and Microsetella norvergica. CPR Type I (approx. 423 ìm silk mesh) recorded up to 250 copepods/segment of silk mesh and CPR Type II (270 ìm silk mesh) recorded dominance of copepods with 121 ± 201 zooplankton specimens/segment with a maximum of 1537 ind. /section, in these samples only 1% were copepod nauplii larvae and 26% were Oithona similis. Without considering nauplii larvae, both total number of specimens of copepods by sample (537 ± 386 copepods/sample) and the relative contribution of Oithona similis (average: 77% range 55-99%) got with the pump-net system were higher than the corresponding values registered with CPR Type II. Although pump-net system was not autonomous, it allows estimating absolute abundances and it has the advantage of solving two CPR problems; clogging of the mesh and catching efficiency of nauplii larvae and small species of copepods. As a result, the use of both instruments together would allow calibrate and complement the CPR results.