Gelatinous macrozooplankton in the canyons and basins
the Gulf of Maine
Francesc Pagès, Ph.D.
Institut de Ciències del Mar (CSIC)
Wednesday, June 2, 2004
Pacific Forum – 3:00 p.m.
In September 2002 and 2003,a Johnson-Sea-Link submersible conducted a cruise in the Gulf of Maine for investigating the trophodynamics of the physonect siphonophore Nanomia cara, a strong predator of copepods. Relevant observations were also obtained about the gelatinous macrozooplankton populations living down 950 meters depth in four submarine canyons. Ctenophores, particularly Bolinopsis infundibulum and Beroë cucumis, were the most abundant and conspicuous organisms along the water column. In total 80 species were collected (38 siphonophores, 18 hydroidomedusae, 9 scyphomedusae, 8 ctenophores, 3 salps, 3 molluscs and 1 pyrosomid). At least 17 species (22%), mostly siphonophores, are undescribed. Twenty-three zooplankton hauls were also done with a MOCNESS net from near the seafloor. Neither Bolinopsis nor Nanomia specimens were collected by this net. The results demonstrate that Johnson-Sea-Link submersibles are unique tools for the in situ observation and collection of large, fragile, mesopelagic gelatinous species, many of them undescribed or poorly known.