Abstract

LOPEZ PERALTA, Raúl Hernando. CHAETOGNATHA (APHRAGMOPHORA) ABUNDANCE AND BIOMASS IN THE EPIPELAGIC ZONE OF THE COLOMBIAN PACIFIC. rev.udcaactual.divulg.cient. [online]. 2018, vol.21, n.1, pp.187-196. ISSN 0123-4226.  https://doi.org/10.31910/rudca.v21.n1.2018.677.

Due to the importance of chaetognaths, their high predatory impact and their role in energy transfer from phytoplankton to higher trophic levels, their abundance and dry biomass were evaluated for the first time in relation to thermohaline structure and light influence in the Colombian Pacific Ocean (CPO) in September 2007. Twenty-three samples were obtained with a bongo net (294 μm mesh) by oblique trawls in the epipelagic stratum in equal number of stations distributed throughout the CPO. Abiotic conditions were characteristic of a normal period, with possible benefit to the chaetognath community as a result of food availability. While adults dominated in the intermediate (x̅= 240 ind/100 m3, 34.7 g/100 m3) and oceanic (x̅= 290 ind/100 m3 39.2 g/100 m3) subareas, coastal waters, generally more productive, promoted the spawning, development and higher abundance and biomass of juveniles (910 ind/100 m3, 26.2 g/100 m3), which indicates better adaptation to less saline waters, as well as a more pronounced trophic impact and relevant role to the structure of the zooplankton community when compared to the adult community. It is likely that hydrological dynamics have influenced heterogeneous organism distribution on the epipelagic zone, with a higher biomass-abundance in some coastal and oceanic stations, due to greater trophic supply resulting from upwelling processes, nocturnal vertical migration, and lunar influence, especially during the new moon and first quarter. A preliminary checklist of the chaetognaths is given.

Keywords : Biomass; abundance; upwelling; migration; chaetognaths..

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