Influence of physical processes and freshwater discharge on the seasonality of phytoplankton regime in the Bay of Bengal

Gomes, Helga do Rosário; Goés, Joaquim I.; Saino, Toshiro

doi:10.1016/s0278-4343(99)00072-2

Cited by 236 publications

(174 citation statements)

References 20 publications

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“…Devassy 0 78 82 86 90 94 98 78 82 86 90 94 98 78 82 86 90 94 (1978) suggested 2 possibilities: Some kind of dormant resting stage may be present during nonbloom conditions which goes unnoticed or is misidentified during analyses; or, the organism in the nonbloom season remains distributed throughout the mixed-layer such that sampling at the surface under these conditions will show only a few filaments, and then, at the onset of favourable conditions the filaments become buoyant and come to the surface to form blooms. Recent observations using a video plankton recorder (Davis & McGillicuddy 2006) revealed Trichodesmium colonies not just restricted to the surface but rather to a depth of as much as 130 m.Trichodesmium blooms have been observed on several occasions in the past in the area of our study (Ramamurthy et al 1972, Devassy et al 1978, Gomes et al 2000, Jyothibabu et al 2003. In the areas where we encountered high numbers of Trichodesmium, we sought the help of remote sensing to support our observation.…”

supporting

confidence: 52%

“…The regular timing of the blooms suggests that physical factors such as stratification, winds and current patterns influence these blooms. In the Bay of Bengal, blooms have been observed since 1942 (Ramamurthy et al 1972, Devassy et al 1978 and references therein, Gomes et al 2000, Jyothibabu et al 2003. However, elucidation of spatial and temporal distribution was not attempted in any of the earlier investigations.…”

Section: Introductionmentioning

confidence: 99%

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Influence of environmental settings on the prevalence of Trichodesmium spp. in the Bay of Bengal

Hegde¹,

Anil

Patil³

et al. 2008

Mar. Ecol. Prog. Ser.

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Trichodesmium, an important marine nitrogen-fixing cyanobacteria, is widespread in tropical waters and contributes substantially to the global chemical cycles by new production. The interesting and intriguing feature of Trichodesmium blooms is the suddenness with which the blooms appear and disappear. A well-defined periodicity and annual rhythm of Trichodesmium blooms in the Indian south central coastal environments of the Arabian Sea between February and May is well documented. However, not much is known for the Bay of Bengal. Analysis of the surface water samples collected from the merchant vessels plying between Chennai and Singapore at regular intervals (February 2000 to September 2002 to study the variations in the micro-phytoplankton community indicated that Trichodesmium persists for a large part of the year in the south-eastern part of the Bay of Bengal. Remotely sensed images from 1997 to 2003 also indicated the prevalence of Trichodesmium in the south-eastern part of the Bay during the winter months and in the west (west Bay of Bengal and east Arabian Sea) during summer. This raises the possible role of physical forcing in the dispersal and seeding of Trichodesmium. The prevalence of stratified conditions in the Bay of Bengal almost throughout the year can be one of the causative factors facilitating the preponderance of Trichodesmium. The inter-annual variations observed indicate that the tracking of Trichodesmium will be useful in understanding the biogeochemistry of the region.KEY WORDS: Indian Ocean · Cyanobacteria · Phytoplankton · Arabian Sea · Remote sensing 356: 93-101, 2008 elements such as iron and phosphorous (Karl et al. 1992, Rueter et al. 1992, Mulholland et al. 2002. Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerIn the Indian Ocean Trichodesmium blooms have been recorded since 1942 (Devassy et al. 1978 and references therein). The first report of the blooms in the Arabian Sea was in 1972 (Ramamurthy et al. 1972), and their occurrence with a well-defined periodicity and annual rhythm between February and May has been described as a phenomenon (Devassy et al. 1978). The regular timing of the blooms suggests that physical factors such as stratification, winds and current patterns influence these blooms. In the Bay of Bengal, blooms have been observed since 1942 (Ramamurthy et al. 1972, Devassy et al. 1978 and references therein, Gomes et al. 2000, Jyothibabu et al. 2003. However, elucidation of spatial and temporal distribution was not attempted in any of the earlier investigations. In the present study, which is the first of its kind, surface samples were collected at regular intervals for a period of 3 yr. It was found that Trichodesmium spp. appear regularly during the fall and winter in the Bay of Bengal and make their presence felt during the summer months along the south west coast of India.Remote sensing techniques provide an alternative solution for mapping Trichodesmium on a global scale. Algorithms to detect Trichodes...

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supporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Influence of environmental settings on the prevalence of Trichodesmium spp. in the Bay of Bengal

Hegde¹,

Anil

Patil³

et al. 2008

Mar. Ecol. Prog. Ser.

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“…However, recent measurements using clean techniques (Madhupratap et al, 2003) corroborate the traditional concept that the Bay of Bengal is a region of lesser biological productivity. The reason for this is variously attributed to cloud cover, large sediment load, narrow shelf, stratification, etc (see Qasim, 1977;Sengupta et al, 1977;Radhakrishna, 1978;Gomes et al, 2000). In a recent study Prasanna Kumar et al (2002) showed that the surface and the integrated chlorophyll a in the Bay of Bengal during summer monsoon was 4-5 times lesser than that in the Arabian Sea while the integrated primary productivity was about 8 times less.…”

Section: Introductionmentioning

confidence: 99%

Eddy-mediated biological productivity in the Bay of Bengal during fall and spring intermonsoons

Kumar

Murukesh

Ramaiah

et al. 2007

Deep Sea Research Part I: Oceanographic Research Papers

173

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The signature of cold-core eddies and their role in altering the biological productivity of the Bay of Bengal was examined using two recent sets of hydrographic data collected along the central and western Bay of Bengal during fall (14 September -12 October, 2002) and spring (12 April -7 May, 2003) intermonsoons under the Bay of Bengal Process Studies (BOBPS) programme. Based on the thermohaline structure and the satellite-derived sea-level anomaly maps 9 cyclonic eddies were identified. Out of this, 4 cyclonic eddies -2 each along the central Bay and along the western boundary -occurred during fall intermonsoon 2002, while 5 occurred -3 along the central Bay and 2 along the western boundary -during spring intermonsoon. The eddy depressed the temperature, which varied from 3 o C to 7 o C at 120 m depth. Maximum depression of temperature was associated with spring-time eddies in the northern Bay, where subsurface stability was low. The reduced water column stability in spring leads to greater eddypumping, thereby cooling the water to a greater extent. However, the cyclonic eddies were unable to break the stratification of the top 20m layer, thereby curtailing their effects below this depth during both seasons. Eddypumping not only cooled the water column but also enhanced the nutrient concentrations. This in turn increased the biological productivity of the Bay to 1½-2 times. In addition, the subsurface chlorophyll maximum (SCM), which is generally located between 40 and 70 m in fall and 60 and 90 m in spring intermonsoons, shallowed under the influence of the eddies and also enhanced the chlorophyll concentration in the SCM to more than double. Thus, eddy-pumping of nutrients controls the biological productivity of the Bay of Bengal during both the seasons. In the fall intermonsoon, however, the riverine input of nutrients and sediments in the northern Bay also plays a role in altering the biological productivity. This has an overall implication to the basin-wide new production and export flux and, at least partly, resolves the reason for the comparable annual fluxes of organic carbon

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“…The conditions observed allowed colonization by seed bank, according to Gomes, Goes, and Saino (2000). Our experiment in the greenhouse in fact combined characteristics similar to the natural habitat, probably the expressive light and the conditions of water level resulted in high germination rates of macrophytes.…”

Section: Discussionmentioning

confidence: 58%

<b>Diaspore bank of aquatic macrophytes maintaining species diversity in a Neotropical pond

Ferreira

Catian

Pott

2016

Acta Sci. Biol. Sci.

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ABSTRACT. The diaspore bank is an important component of biological diversity acting mainly as storage and source of diaspores, which also indicate dynamics and patterns of maintenance of plant diversity. We tested the hypothesis that the diaspore bank would be the responsible factor for the maintenance of the aquatic plant species, used two techniques to evaluate the diaspore bank: seedling emergence and direct counting of field samples. Density and richness of the diaspore bank were correlated with plant cover of the aquatic macrophyte communities and also with the euphotic zone radiation in different phases of the hydrological cycle. The diaspore bank is a key factor in maintenance of aquatic macrophyte assemblages in this pond. Nymphaea amazonum was one of the dominant species in the pond and presented temporally peaks of plant cover. Furthermore, depth allowed induction of germination of stored diaspores. Therefore, the diaspore bank may predict which species colonizes a site when environmental characteristics are favorable and allows inferring which processes are linked to changes in structure of aquatic macrophyte assemblages. These mechanisms are the means for recovery of macrophyte species under natural disturbances, represented by water level oscillations in floodplains.Keywords: aquatic plant, plant ecology, seed bank, wetland.Banco de diásporos de macrófitas aquáticas para a manutenção da diversidade das espécies em uma lagoa Neotropical RESUMO. O banco de diásporos é um componente importante da diversidade biológica atuando principalmente como armazenamento e fonte de diásporos, que também indicam a dinâmica e os padrões de manutenção da diversidade vegetal. Testamos a hipótese de que o banco de diásporos seria o fator responsável pela manutenção das espécies de plantas aquáticas, utilizando duas técnicas para avaliar o banco diásporo: emergência das plântulas e contagem direta de amostras de campo. Densidade e riqueza do banco de diásporos foram correlacionadas com cobertura vegetal das comunidades de macrófitas aquáticas e também com a radiação da zona eufótica em diferentes fases do ciclo hidrológico. O banco de diásporos é um fator chave na manutenção das assembleias de macrófitas aquáticas nesta lagoa. Nymphaea amazonum foi uma das espécies dominantes na lagoa temporalmente, apresentou picos de cobertura vegetal. Além disso, a profundidade permitiu a indução da germinação de diásporos armazenados. Portanto, o banco de diásporo é um preditor de quais espécies colonizarão um local quando as características ambientais são favoráveis e permite inferir que os processos estão ligados a mudanças na estrutura das assembleias de macrófitas aquáticas. Estes mecanismos são os meios para a recuperação de espécies de macrófitas sob as perturbações naturais, representados por oscilações do nível de água nas planícies aluviais.Palavras-chave: planta aquática, ecologia vegetal, banco de sementes, pantanal.

show abstract

Influence of physical processes and freshwater discharge on the seasonality of phytoplankton regime in the Bay of Bengal

Cited by 236 publications

References 20 publications

Influence of environmental settings on the prevalence of Trichodesmium spp. in the Bay of Bengal

Influence of environmental settings on the prevalence of Trichodesmium spp. in the Bay of Bengal

Eddy-mediated biological productivity in the Bay of Bengal during fall and spring intermonsoons

<b>Diaspore bank of aquatic macrophytes maintaining species diversity in a Neotropical pond

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