Biophysical Control on Variability in Phytoplankton Production and Composition in the South-Western Tropical Indian Ocean During Monsoon 2014

Tripathy, S.C.; Sabu, P.; Patra, Sivaji; Naik, Ravidas K.; Sarkar, Amit; Venkataramana, V.; Kerkar, Anvita U.; Sudarsanarao, Pandi

doi:10.3389/fmars.2020.00515

Cited by 13 publications

(3 citation statements)

References 72 publications

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“…In addition to a decreasing trend of the BET CPUE, it might also affected by several factors, such as the primary production, fishing technique, and fishing ground. According to [20], the Indian Ocean's north-eastern region may have low primary productivity, which may be aggravated by global warming [21]. Besides that, Indonesian fishermen's capacity to operate in the region below 20 o S, known to have a greater abundance [22], was further obstructed by conventional fishing techniques and laminated wooden-based vessels [23].…”

Section: Resultsmentioning

confidence: 99%

Trends of Indonesia’s bigeye tuna longline fisheries in the Eastern Indian Ocean: Catch per unit effort and length distribution

Hartaty,

Setyadji,

Sadiyah

et al. 2023

E3S Web Conf.

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Bigeye tuna, Thunnus obesus (Lowe, 1839), is one of the primary target species for Indonesian tuna longliners operated in the eastern part of the Indian Ocean. However, the fishing trend and biological information are still scarce despite their importance in developing harvest strategy in the region. The study provides nominal catch per unit effort (CPUE) and length compositions of bigeye tuna caught by the Indonesian tuna longliners from the area. Data were obtained from records made by the onboard scientific observers assigned by the Research Institute for Tuna Fisheries (RITF) from 2006 to 2021. The data covers records from 3180 longline settings in 118 fishing trips in which more than 4 million hooks deployed. The fishing efforts were distributed between 0-35°S and 75-130°E, with 10 to 15 hooks between floats. The highest CPUE was 0.29±0.05 fish per 100 hooks in 2014, and the lowest was 0.09±0.05 fish per 100 hooks in 2021. From 8150 fish measurements in 2006 to 2021, the average size was 117.66±24.13 cm FL, and the dominant size class was 120–130 cmFL. While the average size of BET shows an increasing trend the CPUEs were declining.

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Section: Resultsmentioning

confidence: 99%

Trends of Indonesia’s bigeye tuna longline fisheries in the Eastern Indian Ocean: Catch per unit effort and length distribution

Hartaty,

Setyadji,

Sadiyah

et al. 2023

E3S Web Conf.

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“…These contrasting biogeochemical regimes between different parts of the Indian Ocean imply a diverse and complex response of the marine ecosystem to perturbations. While recent observations showed that the Indian Ocean phytoplankton community has changed due to environmental variations, mechanisms controlling these changes are not well understood (Mishra et al., 2015; Naik et al., 2020; Roxy et al., 2016; Tripathy et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Anthropogenic Iron Deposition Alters the Ecosystem and Carbon Balance of the Indian Ocean Over a Centennial Timescale

Pham

Ito

2021

JGR Oceans

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The Indian Ocean accounts for around one-fifth of the ocean net primary production (Behrenfeld & Falkowski, 1997a) and contains two of the largest oxygen (O 2) minimum zones (OMZs) of the world oceans in the northern part (the Arabian Sea and the Bay of Bengal) (Stramma et al., 2010). In these two regions, phytoplankton growth is generally limited by macronutrients because of the relatively shallow mixed layer and the Ekman downwelling that transports nutrients away from the euphotic layer. Furthermore, the low O 2 water in the OMZs promote nitrogen (N) loss through denitrification (Moore et al., 2013; Wang et al., 2019). In the northern Indian Ocean, the concentration of dissolved iron (dFe) is relatively high (∼0.6 nM in the surface and ∼1.5 nM in the subsurface 200-1,000 m water) due to relatively high dFe inputs from atmospheric deposition and reduced sediments over the continental shelves (Chinni et al., 2019; Nishioka et al., 2013). However, Fe can still be a limiting factor for the nitrogen-fixer diazotrophs, which have a higher demand for Fe than other phytoplankton (

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“…These contrasting biogeochemical regimes between different parts of the Indian Ocean imply a diverse and complex response of the marine ecosystem to perturbations. While recent observations showed that the Indian Ocean phytoplankton community has changed due to environmental variations, mechanisms controlling these changes are not well understood (Mishra et al, 2015;Naik et al, 2020;Roxy et al, 2016;Tripathy et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Anthropogenic iron deposition alters the ecosystem and carbon balance of the Indian Ocean over a centennial timescale

Pham

Ito

2020

Preprint

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<p>Phytoplankton growth in the Indian Ocean is generally limited by macronutrients (nitrogen: N and phosphorus: P) in the north and by micronutrient (iron: Fe) in the south. Increasing anthropogenic atmospheric deposition of N and dissolved Fe (dFe) into the ocean can thus lead to significant responses from marine ecosystems in this ocean basin. Previous modeling studies investigated the impacts of anthropogenic nutrient deposition on the ocean, but their results are uncertain due to incomplete representations of Fe cycling. We use a state-of-the-art ocean ecosystem and Fe cycling model to evaluate the transient responses of ocean productivity and carbon uptake in the Indian Ocean, focusing on the centennial time scale. The model incorporates all major external sources and represents a complicated internal cycling process of Fe, thus showing significant improvements in reproducing observations. Sensitivity simulations show that after a century of anthropogenic deposition, increased dFe stimulates diatoms productivity in the southern Indian Ocean poleward of 50&#8304;S and the southeastern tropics. Diatoms production weakens in the south of the Arabian Sea due to the P limitation, and diatoms are outcompeted there by coccolithophores and picoplankton, which have a lower P demand. These changes in diatoms and coccolithophores productions alter the balance between the organic and carbonate pumps in the Indian Ocean, increasing the carbon uptake in the south of 50&#8304;S and the southeastern tropics while decreasing it in the Arabian Sea. Our results reveal the important role of ecosystem dynamics in controlling the sensitivity of carbon fluxes in the Indian Ocean under the impact of anthropogenic nutrient deposition over a centennial timescale.</p>

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Biophysical Control on Variability in Phytoplankton Production and Composition in the South-Western Tropical Indian Ocean During Monsoon 2014

Cited by 13 publications

References 72 publications

Trends of Indonesia’s bigeye tuna longline fisheries in the Eastern Indian Ocean: Catch per unit effort and length distribution

Trends of Indonesia’s bigeye tuna longline fisheries in the Eastern Indian Ocean: Catch per unit effort and length distribution

Anthropogenic Iron Deposition Alters the Ecosystem and Carbon Balance of the Indian Ocean Over a Centennial Timescale

Anthropogenic iron deposition alters the ecosystem and carbon balance of the Indian Ocean over a centennial timescale

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