Zooplankton Growth, Respiration and Grazing on the Australian Margins of the Tropical Indian and Pacific Oceans

Abstract

The specific activity of aminoacyl-tRNA synthetases (spAARS), an index of growth rate, and of the electron transport system (spETS), an index of respiration, was measured in three size fractions (73–150 μm, >150 μm and >350 μm) of zooplankton during five cruises to tropical coastal waters of the Kimberley coast (North West Australia) and four cruises to waters of the Great Barrier Reef (GBR; North East Australia). The N-specific biomass of plankton was 3–4-fold higher in the Kimberley than on the GBR in all 3 size classes: Kimberley 1.27, 3.63, 1.94 mg m-3; GBR 0.36, 0.88 and 0.58 mg m-3 in the 73–150 μm, >150 μm and >350 μm size classes, respectively. Similarly, spAARS activity in the Kimberley was greater than that of the GBR: 88.4, 132.2, and 147.6 nmol PPi hr-1 mg protein -1 in the Kimberley compared with 71.7, 82.0 and 83.8 nmol PPi hr-1 mg protein -1 in the GBR, for the 73–150 μm, >150 μm and >350 μm size classes, respectively. Specific ETS activity showed similar differences in scale between the two coasts: 184.6, 148.8 and 92.2 μL O2 hr-1 mg protein-1 in the Kimberley, against 86.5, 88.3 and 71.3 μL O2 hr-1 mg protein-1 in the GBR. On the basis of these measurements, we calculated that >150 μm zooplankton grazing accounted for 7% of primary production in the Kimberley and 8% in GBR waters. Area-specific respiration by >73 μm zooplankton was 7-fold higher in the Kimberley than on the GBR and production by >150 μm zooplankton was of the order of 278 mg C m-2 d-1 in the Kimberley and 42 mg C m-2 d-1 on the GBR. We hypothesize that the much stronger physical forcing on the North West shelf is the principal driver of higher rates in the west than in the east of the continent.

Mesozooplankton structure and functioning in the western tropical South Pacific along the 20° parallel south during the OUTPACE survey (February–April 2015)

“…Recent observations 10 suggested consumption of UCYN-A and UCYN-B by diverse calanoid copepods (Scavotto et al, 2015;Conroy et al, 2017). respectively) calculated using the allometric relationships of Ikeda (1985), based on individual dry weight estimates of the different zooplankton taxa, and on temperature and chlorophyll levels recorded during OUTPACE, were in the range of literature values for metazooplankton and copepods in the inter-tropical zone (Ikeda, 1985;Mauchline, 25 1998;Hernandez-Leon et al, 2008;McKinnon et al, 2015), thus validating this approach.…”

Geographic variability in taxonomic composition, standing stock, and productivity of the mesozooplankton community around the Kuroshio Current in the East China Sea

“…and comparable to those at the Australian tropical coast(McKinnon et al, 2015), indicating high productivity. Yebra, Hern andez-L eon, Almeida, B ecogn ee, and Rodr ıguez (2004) also used measured protein synthetase activity to demonstrate that the copepod productivity is enhanced by high phytoplankton biomass.…”

“…This is important because protein synthetase activity is a widely accepted index of nutritional condition and growth in zooplankton populations (Yebra, Berdalet, et al., ; Yebra, Harris, Wilson, Davidson, & Montagnes, ; Yebra & Hernández‐Léon, ; Yebra et al., ). Community‐based protein synthetase activities measured in the three regions were much higher than those in the Greenland Sea (Yebra, Berdalet, et al., ; Yebra, Harris, et al., ) and comparable to those at the Australian tropical coast (McKinnon et al., ), indicating high productivity. Yebra, Hernández‐Léon, Almeida, Bécognée, and Rodríguez () also used measured protein synthetase activity to demonstrate that the copepod productivity is enhanced by high phytoplankton biomass.…”

Benthic uptake of phytoplankton and ocean‐reef exchange of particulate nutrients on a tide‐dominated reef

“…Large seasonal differences in coastal water quality can occur in regions with a monsoonal climate as delivery of terrestrial sediment and nutrients to coastal waters occurs primarily during wet season pulsed events (Furnas ; Devlin and Brodie ), resulting in elevated coastal Chl a (Furnas et al ; Schaffelke et al ). Our study is one of the first to measure wet season Chl a and particulate nutrients in the coastal Kimberley (e.g., McKinnon et al a , b ; Furnas and Carpenter ). Concentrations of Chl a (Fig.…”