Seasonal variation of oxidative biomarkers in gills and digestive gland of green-lipped mussel Perna viridis from Arabian Sea     

X.N. Verlecar  K.B. Jena  G.B.N. Chainy 《Estuarine, Coastal and Shelf Science》2008,76(4):745-752

Investigations on seasonal variation in oxidative stress biomarkers were carried out on the natural population of green-lipped mussel Perna viridis collected from Bambolim beach area of Goa. Oxidative stress indices such as lipid peroxidation (LPX), hydrogen peroxide (H₂O₂), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione transferase (GST), glutathione reductase (GR), reduced glutathione (GSH) and ascorbic acid (ASA) were measured in gills and digestive gland of P. viridis during February, May, August and November. The present study reveals two important aspects regarding the antioxidant defence status of tissues of P. viridis. Firstly, antioxidant capacity of tissues of P. viridis exhibits seasonal variation. Secondly, various components of antioxidant capacity such as oxidative stress markers, levels of antioxidant enzymes and small antioxidant molecules vary differently in tissues with respect to different seasons. Although the oxidative stress status of gills and digestive gland of P. viridis expressed in terms of LPX and H₂O₂ was the lowest in February, its level was maximal in gills and digestive gland during May and November, respectively. While activities of SOD and GPX of tissues of P. viridis were found to be low in August, activities of CAT and GR were recorded to be low in February. GST activity in gills although remained high in February, in digestive gland elevated values were recorded in August and November. A seasonal variation in the levels of small antioxidant molecules was also noticed. Among non enzymatic antioxidants ASA content of tissues was maximal in May and August in comparison to February and November, but GSH remained high in November. It therefore appears that environmental factors may play a crucial role in regulating the oxidative stress capacity of tissues of P. viridis.  相似文献   

Controls of dimethyl sulphide in the Bay of Bengal during BOBMEX-Pilot cruise 1998   总被引：1，自引：0，他引：1  

D. M. Shenoy  M. Dileep Kumar  V. V. S. S. Sarma 《Journal of Earth System Science》2000,109(2):279-283

The air-sea exchange is one of the main mechanisms maintaining the abundances of trace gases in the atmosphere. Some of these, such as carbon dioxide and dimethyl sulphide (DMS), will have a bearing on the atmospheric heat budget. While the former facilitates the trapping of radiation (greenhouse effect) the latter works in the opposite direction through reflectance of radiation back into space by sulphate aerosols that form from oxidation of DMS in atmosphere. Here we report on the first measurements made on DMS in the Bay of Bengal and the factors regulating its abundance in seawater. Phytoplankton alone does not seem to control the extent of DMS concentrations. We find that changes in salinity could effectively regulate the extent of DMSP production by marine phytoplankton. In addition, we provide the first ever evidence to the occurrence of DMS precursor, DMSP, in marine aerosols collected in the boundary layer. This suggests that the marine aerosol transport of DMSP will supplement DMS gaseous evasion in maintaining the atmospheric non-sea salt sulphur budget.  相似文献   

Evaluation of a high-resolution wave hindcast model SWAN for the West Mediterranean basin     

《Applied Ocean Research》2019

This study aims to present an evaluation and implementation of a high-resolution SWAN wind wave hindcast model forced by the CFSR wind fields in the west Mediterranean basin, taking into account the recent developments in wave modelling as the new source terms package ST6. For this purpose, the SWAN model was calibrated based on one-year wave observations of Azeffoune buoy (Algerian coast) and validated against eleven wave buoys measurements through the West Mediterranean basin. For the calibration process, we focused on the whitecapping dissipation coefficient C_ds and on the exponential wind wave growth and whitecapping dissipation source terms. The statistical error analysis of the calibration results led to conclude that the SWAN model calibration corrected the underestimation of the significant wave height hindcasts in the default mode and improved its accuracy in the West Mediterranean basin. The exponential wind wave growth of Komen et al (1984) and the whitecapping dissipation source terms of Janssen (1991) with C_ds = 1.0 have been thus recommended for the western Mediterranean basin. The comparison of the simulation results obtained using this calibrated parameters against eleven measurement buoys showed a high performance of the calibrated SWAN model with an average scatter index of 30% for the significant wave heights and 19% for the mean wave period. This calibrated SWAN model will constitute a practical wave hindcast model with high spatial resolution (˜3 km) and high accuracy in the Algerian basin, which will allow us to proceed to a finer mesh size using the SWAN nested grid system in this area.  相似文献   

Baseline of organotin pollution in fishes, clams, shrimps, squids and crabs collected from the west coast of India     

Jadhav S  Bhosale D  Bhosle N 《Marine pollution bulletin》2011,62(10):2213-2219

Organotins, especially tributyltins (TBT) are highly toxic to many marine organisms. These compounds are introduced in marine waters by ship trafficking, ship scrapping activities, as antifouling compounds and sewage disposal. Marine fishes, crustaceans and molluscans are easily prone to organotins contamination. In view of this, a baseline monitoring study was conducted in order to establish the levels of organotins in edible marine fishes, bivalves, shrimps, squids and crabs collected from Mumbai, Goa and Karwar on the west coast of India. At these locations average organotin concentration found in fishes, clams, shrimps, squids and crabs was 108, 852, 179, 70 and 89 ng Sn g⁻¹ dw, respectively. In all the samples butyltins dominated over phenyltins. The levels of organotins suggest that all the organisms were contaminated with organotins and their consumption may pose health problems to humans.  相似文献   

On the dominance of pre-existing swells over wind seas along the west coast of India     

V.M. Aboobacker  R. RashmiP. Vethamony  H.B. Menon 《Continental Shelf Research》2011,31(16):1701-1712

Wave data collected off Goa along the west coast of India during February 1996-May 1997 has been subjected to spectral analysis, and swell and wind sea parameters have been estimated by separation frequency method. Dominance of swells and wind seas on monthly and seasonal basis has been estimated, and the analysis shows that swells dominate Goa coastal region not only during southwest monsoon (93%), but also during the post-monsoon (67%) season. Wind seas are dominant during the pre-monsoon season (51%). The mean wave periods (T_m) during southwest monsoon are generally above 5 s, whereas T_m is below 5 s during other seasons. Co-existence of multiple peaks (from NW and NE) was observed in the locally generated part of the wave spectrum, especially during the post-monsoon season. NCEP reanalysis winds have been used to analyse active fetch available in the Indian Ocean, from where the predominant swells propagate to the west coast of India. A numerical model was set up to simulate waves in the Indian Ocean using flexible mesh bathymetry. The correlation coefficients between measured and modelled significant wave heights and mean wave periods are 0.96 and 0.85, respectively. Numerical simulations reproduced the swell characteristics in the Indian Ocean, and from the model results potential swell generation areas are identified. The characteristics of swells associated with tropical storms that prevail off Goa during 1996 have also been analysed.  相似文献   

Influence of morphodynamic variability over seasonal beach sediments and its probable effect on coastal development     

A.R. Gujar  P. GanesanS.D. Iyer  S.S. GaonkarN.V. Ambre  V.J. LovesonP.G. Mislankar 《Ocean & Coastal Management》2011,54(7):514-523

Seasonal variations and effect of oceanographic processes such as erosion and/or accretion along beaches are important to understand their impact on coastal morphological variations. Detailed investigations were taken up to analyse the volumetric and morphologic variations of the beaches between Pirwadi (latitude 16° 12′ N, longitude 73° 26.55′ E) and Sarjekot (latitude 16° 05′ N, longitude 73° 27.80′ E) of South Maharashtra, Central West Coast of India. This stretch is known for its rich deposits of ilmenite, magnetite and chromite. This study is based on the results of seasonal topographic profiles carried out between October 2004 and December 2005. The volume variations of the sediments, i.e. an account of accretion and/or erosion, were estimated considering the October 2004 profile as the base reference, over which the values of other seasons are compared. The results of beach profiling from Pirwadi to Talashil indicate the seasonal variations in the beach configuration and the gradient.In the studied areas the vulnerable areas are Tondavali, Talashil and Pirwadi in a decreasing order of erosion while Bagwadi shows lesser erosion. Several reasons can be attributed for these erosional trends. Among which the prominent are rip currents, wave dynamics, variable coastal configuration, beach gradient and temporary monsoonal seaward flowing streams. In contrast, significant deposition occurs throughout the year at Hirlewadi due to sediment transported by due south by littoral currents. Therefore, considering the sensitivity of the fragile coastal system, future developmental activities (mining, tourism, etc.) need to be planned in tandem with the required protective measures such as construction of reinforced concrete curved wall and geotextiles.  相似文献   

An evaluation of flora from coastal sand dunes of India: Rationale for conservation and management     

Rouchelle S. RodriguesAntonio Mascarenhas  Tanaji G. Jagtap 《Ocean & Coastal Management》2011,54(2):181-188

A key component that guarantees stability of coastal sand dunes (CSDs) is vegetation. In this study, the floristic composition and distribution from CSDs of India is reviewed. Analysis revealed a total 338 species of CSD flora, of which 92 species are found to be common to the west and east coasts. The west coast showed a greater diversity than the east coast, accounting for 267 and 163 species respectively. Fabaceae members dominated the flora and 62% of dune species exhibited an herbaceous habit. The non-metric multi-dimensional scaling (nMDS) resulted in three groups at 20% similarity. The CSD vegetation appeared to be more influenced by the geological setting and climatology of the region. The higher number of coastal dune species along the west coast is attributed to larger and extensive sandy areas. The CSD flora of India is under constant anthropogenic pressure due to rapid elimination of sand dunes and its associated vegetation. The prevailing Coastal Regulation Zone (CRZ) notification does not guarantee the health of sand dune flora. A coastal vegetation conservation policy that ensures a succession of species in the form of a three layered biozone is proposed as a long term sustainable option to maintain biodiversity of coastal flora.  相似文献   

Beach rocks of the Central West Coast of India   总被引：1，自引：0，他引：1  

B. G. Wagle 《Geo-Marine Letters》1990,10(2):111-115

Along the central west coast of India several beach rock exposures have been observed in the intertidal zone, as well as 2–4 m above the present day high water line. Beach rock has almost the same general composition as the loose beach sand over which it lies. It takes the broad morphology of the intertidal zone of the beach in which it developed and it shows similar internal structures. Most of it is medium to coarse grained but some is fine to medium grained. The constituents are calcite, aragonite, quartz, feldspar, traces of black (heavy) minerals, rock fragments and shells. Carbonate reaches up to 97% (% wt).  相似文献   

Fluid-driven Hydrovolcanic Activity along Fracture Zones and near Seamounts: Evidence from Deep-sea Fe-rich Spherules,Central Indian Ocean Basin     

Ankeeta AMONKAR  Sridhar D. IYER  Elapavalooru V.S.S.K. BABU  Natarajan SHAILAJHA  Areef SARDAR  S. MANJU 《《地质学报》英文版》2021,95(5):1591-1603

An insight on occurrence of Fe-rich spherules from the Central Indian Ocean Basin (CIOB) provides an understanding of their distribution at a water depth of >5,000 m. In the present study, Fe-rich spherules are identified to occur in two different sediment types (i.e., siliceous and pelagic) and tectonic settings (i.e. near seamounts and fracture zones). These are single spheres or aggregates, of different sizes (63 to 390 μm) and show textural variability (smooth/quenched, brickwork, corkscrew, interlocking and dendritic). A comparative study based on physical morphology and chemical composition suggests a common mechanism of formation. The association of spherules with fracture zones (FZ) and seamounts signifies that morpho-tectonic features play an important role in fluid-driven hydrovolcanism. Based on the evidence and geologic conditions existing in the basin, we conclude that molten fuel-coolant interaction (MFCI) coupled with submarine hydrothermal exhalations could be an ideal mechanism for the formation of spherules and Fe-particles. The accretion of the spherules on the surface sediments could be a result of recent volcanic phenomena, while those occurring at different depths (280–355, and 460–475 cm-bsf) within the sediment core indicate two different episodes. The study provides a global implication in understanding fluid-driven magmatism in a deep-sea intraplate environment.  相似文献   

Simulating the daily discharge of the Mandovi River,west coast of India     

K. Suprit  D. Shankar  V. Venugopal  N.V. Bhatkar 《水文科学杂志》2013,58(4):686-704

Abstract

A hydrological modelling framework was assembled to simulate the daily discharge of the Mandovi River on the Indian west coast. Approximately 90% of the west-coast rainfall, and therefore discharge, occurs during the summer monsoon (June–September), with a peak during July–August. The modelling framework consisted of a digital elevation model (DEM) called GLOBE, a hydrological routing algorithm, the Terrestrial Hydrological Model with Biogeochemistry (THMB), an algorithm to map the rainfall recorded by sparse raingauges to the model grid, and a modified Soil Conservation Service Curve Number (SCS-CN) method. A series of discharge simulations (with and without the SCS method) was carried out. The best simulation was obtained after incorporating spatio-temporal variability in the SCS parameters, which was achieved by an objective division of the season into five regimes: the lean season, monsoon onset, peak monsoon, end-monsoon, and post-monsoon. A novel attempt was made to incorporate objectively the different regimes encountered before, during and after the Indian monsoon, into a hydrological modelling framework. The strength of our method lies in the low demand it makes on hydrological data. Apart from information on the average soil type in a region, the entire parameterization is built on the basis of the rainfall that is used to force the model. That the model does not need to be calibrated separately for each river is important, because most of the Indian west-coast basins are ungauged. Hence, even though the model has been validated only for the Mandovi basin, its potential region of application is considerable. In the context of the Prediction in Ungauged Basins (PUB) framework, the potential of the proposed approach is significant, because the discharge of these (ungauged) rivers into the eastern Arabian Sea is not small, making them an important element of the local climate system.

Editor D. Koutsoyiannis; Associate editor S. Grimaldi

Citation Suprit, K., Shankar, D., Venugopal, V. and Bhatkar, N.V., 2012. Simulating the daily discharge of the Mandovi River, west coast of India. Hydrological Sciences Journal, 57 (4), 686–704.  相似文献