Further studies of plankton ecosystems in the eastern Indian Ocean. VI. Ecology of the Euphausiacea

1977 ◽  
Vol 28 (5) ◽  
pp. 627 ◽  
Author(s):  
PS McWilliam
Keyword(s):  
Indian Ocean ◽  
Food Resources ◽  
Water Masses ◽  
Eastern Indian Ocean ◽  
Subtropical Water ◽  
Larvae And Juveniles ◽  
Larval Distribution ◽  
Living Species ◽  
Breeding Condition

Examination of 26 427 euphausiids from 175 samples taken by vertical hauls in the upper 200-m stratum along the 110°E. meridian during 1962-63 indicated that day samples contained mainly larvae and juveniles whereas night samples contained more adults. The following six species of small euphausiids were the most abundant and ubiquitous: Euphausia mutica, E. tenera, E. brevis, Stylocheiron carinatum, S. suhmii, and S. Affine. Their distribution overlapped according to the distribution, in the upper 150 m, of the tropical and subtropical water masses and their mixtures. These species were commonly observed in breeding condition. Their larval distribution was related to the distribution of the breeding adults. The rarer and less ubiquitous species, which were mainly younger stages and deeper living species, showed more pronounced relationships with seasonal water movements. Food resources appeared more important than temperature and salinity in influencing distribution, abundance, and association of species.

Nd and Pb isotope evolution of deep water masses in the eastern Indian Ocean during the past 33 Myr

2006 ◽  
Vol 226 (3-4) ◽  
pp. 264-279 ◽  
Author(s):  
Martin Frank ◽  
Nicholas Whiteley ◽  
Tina van de Flierdt ◽  
Ben C. Reynolds ◽  
Keith O'Nions
Keyword(s):  
Indian Ocean ◽  
Deep Water ◽  
Water Masses ◽  
Eastern Indian Ocean ◽  
Pb Isotope ◽  
The Past

scholarly journals Formation and maintenance of high-nitrate, low pH layers in the Eastern Indian Ocean and the role of nitrogen fixation

2013 ◽  
Vol 10 (3) ◽  
pp. 3951-3976 ◽  
Author(s):  
A. M. Waite ◽  
V. Rossi ◽  
M. Roughan ◽  
B. Tilbrook ◽  
J. Akl ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Indian Ocean ◽  
Dissolved Oxygen ◽  
Tropical Indian Ocean ◽  
Water Masses ◽  
Eastern Indian Ocean ◽  
N Fixation ◽  
Dissolved Carbon ◽  
Leeuwin Current ◽  
Ningaloo Reef

Abstract. We investigate the biogeochemistry of Low Dissolved Oxygen High Nitrate layers forming against the backdrop of several interleaving regional water masses in the Eastern Indian Ocean, off northwest Australia adjacent to Ningaloo Reef. These water masses, including the forming Leeuwin Current, have been shown directly to impact the ecological function of Ningaloo Reef and other iconic coastal habitats downstream. Our results indicate that LODHN layers are formed from multiple subduction events of the Eastern Gyral Current beneath the Leeuwin Current (LC); the LC originates from both the Indonesian Throughflow and tropical Indian Ocean. Density differences of up to 0.025 kg m−3 between the Eastern Gyral Current and the Leeuwin Current produce sharp gradients that can trap high concentrations of particles (measured as low transmission) along the density interfaces. The oxidation of the trapped particulate matter results in local depletion of dissolved oxygen and regeneration of dissolved nitrate (nitrification). We document an associated increase in total dissolved carbon dioxide, which lowers the seawater pH by 0.04 units. Based on isotopic measurements (δ15N and δ18O) of dissolved nitrate, we determine that ∼40–100% of the nitrate found in LODHN layers is likely to originate from nitrogen fixation, and that regionally, the importance of N fixation in contributing to LODHN layers is likely be highest at the surface and offshore.

Further studies of plankton ecosystems in the eastern Indian Ocean. VIII. Seasonal, diurnal, and latitudinal variations in abundance of Euthecosomata along the 110°E. meridian

1977 ◽  
Vol 28 (5) ◽  
pp. 663 ◽  
Author(s):  
M Sakthivel
Keyword(s):  
Indian Ocean ◽  
Water Mass ◽  
Eastern Indian Ocean ◽  
The South ◽  
Subtropical Water ◽  
Maximum Abundance ◽  
Tropical Water ◽  
Nocturnal Increase ◽  
Latitudinal Variations ◽  
Peak Abundance

A number of tropical euthecosomes reached peak abundance in the northern tropical water mass between 9 and 20� s. during the south-east monsoon (May-September), with the maximum abundance north of 14� N. Creseis virgula, Hyalocylis striata, Diacria quadridentata and Cavolinia longirostris were typical of this water mass. A few species such as Limacina lesueuri, Styliola subula, Cuvierina columnella and Cavolinia inflexa reached their maximum abundance at other times of the year in the subtropical water mass (south of 20�S.). Limacina bulimoides was at a maximum around 14�S. during September-November and there was a second maximum around 23�S. (in different months). Nocturnal increase in occurrence and abundance was observed in Limacina leseuri, L. helicina rangii, Clio pyramidata, C.p. lanceolata, Styliola subula, Cuvierina columnella, Diacria quadridentata and Cavolinia inflexa.

scholarly journals Formation and maintenance of high-nitrate, low pH layers in the eastern Indian Ocean and the role of nitrogen fixation

2013 ◽  
Vol 10 (8) ◽  
pp. 5691-5702 ◽  
Author(s):  
A. M. Waite ◽  
V. Rossi ◽  
M. Roughan ◽  
B. Tilbrook ◽  
P. A. Thompson ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Indian Ocean ◽  
Dissolved Oxygen ◽  
Tropical Indian Ocean ◽  
Water Masses ◽  
Eastern Indian Ocean ◽  
N Fixation ◽  
Dissolved Carbon ◽  
Leeuwin Current ◽  
Ningaloo Reef

Abstract. We investigated the biogeochemistry of low dissolved oxygen high-nitrate (LDOHN) layers forming against the backdrop of several interleaving regional water masses in the eastern Indian Ocean, off northwest Australia adjacent to Ningaloo Reef. These water masses, including the forming Leeuwin Current, have been shown directly to impact the ecological function of Ningaloo Reef and other iconic coastal habitats downstream. Our results indicate that LDOHN layers are formed from multiple subduction events of the Eastern Gyral Current beneath the Leeuwin Current (LC); the LC originates from both the Indonesian Throughflow and tropical Indian Ocean. Density differences of up to 0.025 kg m−3 between the Eastern Gyral Current and the Leeuwin Current produce sharp gradients that can trap high concentrations of particles (measured as low transmission) along the density interfaces. The oxidation of the trapped particulate matter results in local depletion of dissolved oxygen and regeneration of dissolved nitrate (nitrification). We document an associated increase in total dissolved carbon dioxide, which lowers the seawater pH by 0.04 units. Based on isotopic measurements (δ15N and δ18O) of dissolved nitrate, we determine that ~ 40–100% of the nitrate found in LDOHN layers is likely to originate from nitrogen fixation, and that, regionally, the importance of N-fixation in contributing to LDOHN layers is likely to be highest at the surface and offshore.

scholarly journals Impact of the Strong Downwelling (Upwelling) on Small Pelagic Fish Production during the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean off Java

Climate ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 29
Author(s):  
Jonson Lumban-Gaol ◽  
Eko Siswanto ◽  
Kedarnath Mahapatra ◽  
Nyoman Metta Nyanakumara Natih ◽  
I Wayan Nurjaya ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Pelagic Fish ◽  
Eastern Indian Ocean ◽  
Fish Production ◽  
Small Pelagic Fish ◽  
Field Surveys ◽  
Chl A ◽  
Positive Indian Ocean Dipole ◽  
The Impact

Although researchers have investigated the impact of Indian Ocean Dipole (IOD) phases on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the influence of negative (positive) IOD phases on chlorophyll a (Chl-a) concentrations as an indicator of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off Java. We also conducted field surveys in the EIO off Palabuhanratu Bay at the peak (October) and the end (December) of the 2019 positive IOD phase. Our findings show that the Chl-a concentration had a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increase) in small pelagic fish production in the EIO off Java.

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