Macrozooplankton Biomass in a Warm-Core Gulf Stream Ring: Time Series Changes in Size Structure, Taxonomic Composition, and Vertical Distribution

Author(s): Davis CS and Wiebe PH

Abstract

Macrozooplankton size structure and taxonomic composition in warm-core ring 82B was examined from a time series (March, April, June) of ring center MOCNESS (1 m) samples. Size distributions of 15 major taxonomic groups were determined from length measurements digitized from silhouette photographs of the samples. Silhouette digitization allows rapid quantification of Zooplankton size structure and taxonomic composition. Length/weight regressions, determined for each taxon, were used to partition the biomass (displacement volumes) of each sample among the major taxonomic groups. Zooplankton taxonomic composition and size structure varied with depth and appeared to coincide with the hydrographic structure of the ring. In March and April, within the thermostad region of the ring, smaller herbivorous/omnivorous Zooplankton, including copepods, crustacean larvae, and euphausiids, were dominant, whereas below this region, larger carnivores, such as medusae, ctenophores, fish, and decapods, dominated. Copepods were generally dominant in most samples above 500 m. Total macrozooplankton abundance and biomass increased between March and April, primarily because of increases in herbivorous taxa, including copepods, crustacean larvae, and larvaceans. A marked increase in total macrozooplankton abundance and biomass between April and June was characterized by an equally dramatic shift from smaller herbivores (1.0–3.0 mm) in April to large herbivores (5.0–6.0 mm) and carnivores (>15 mm) in June. Species identifications made directly from the samples suggest that changes in trophic structure resulted from seeding type immigration and subsequent in situ population growth of Slope Water zooplankton species.

 

Similar Articles

Wind-driven coastal upwelling along the western boundary of the Bay of Bengal during the southwest monsoon

Author(s): Shetye SR, Shenoi SSC, Gouveia AD, Michael GS, Sundar D, et al.

The Western Boundary Current of the seasonal subtropical gyre in Bay of Bengal

Author(s): Shetye SR, AD Gouveia, SSC Shenoi, DSundar, GSMichael, et al.

Hydrography and circulation in the western Bay of Bengal during the northeast monsoon

Author(s): Shetye SR, Gouveia AD, Shankar D, Shenoi SSC, Vinayachandran PN, et al.

Observation of the western boundary current of the Bay of Bengal Deep-Sea Res 44:135-145

Author(s): Sanilkumar KV, Kuruvilla TV, Jogendranath D, and Rao RR

Eddy-mediated biological productivity in the Bay of Bengal during fall and spring intermonsoons Deep Sea Research II 54: 1619-1640

Author(s): Prasanna Kumar S, Nuncio M, Ramaiah N, Sardesai S, Narvekar, Jayu, Fernandes, Veronica, & Paul, Jane T

Are eddies nature’s trigger to enhance biological productivity in the Bay of Bengal? Geophys Res Lett 31

Author(s): Prasanna Kumar S, Nuncio M, Narvekar J, Kumar A, Sardesai S, et al.

Seasonal cycle of physicalforcing and biological response in the Bay of BengalIndian J Mar Sci 39: 388-405

Author(s): Prasanna Kumar S, Nuncio M, Narvekar J, Ramaiah N, Sardessai S, et al

Influence of basin-scale and mesoscale physical processes onbiological productivity in the Bay of Bengal during the summer monsoon

Author(s): Muraleedharan KR, Jasmine P, Achuthankutty CT, Revichandran C, Dineshkumar PK, et al

ICES zooplankton methodology manual

Author(s): Harris RP, Wiebe PH, Lenz JH, Skjoldal R & Huntley M

Detection of Bay of Bengaleddies from Topex and in situ observations

Author(s): Gopalan AKS, GopalaKrishna VV, Ali MM, Sharma R

Forcing mechanisms of the Bay of Bengal circulation Current SciIndia 71: 753-763

Author(s): Vinayachandran PN, Shetye SR, Sengupta D, Gadgil S

Development of a subsurface chlorophyll maximum at the entrance to the Gulf of Finland, Baltic Sea

Author(s): Kononen KJ, S Hallfors, M Kokkonen, H Kuosa, J Laanemets, J Pavelson

Analysis of Marine Ecosystems

Author(s): Owen RW

Vertical flux of respiratory carbon by oceanic diel migrant biota Deep-Sea Res 37: 685–694

Author(s): Longhurst AR, Bedo A, Harrison WG, Head EJH, Sameoto DD

Zooplankton vertical migration and the active transport of dissolved organic and inorganic carbon in the Sargasso

Author(s): Steinberg DK, Carlson CA, Bates NR, Goldthwait SA, Madin LP, et al.