Dynamics of chromophoric dissolved organic matter in Mandovi and Zuari estuaries - A study through in situ and satellite data

The spatial and temporal distribution of absorption of chromophoric dissolved organic matter at 440 nm (a CDOM (440)) in the Mandovi and Zuari estuaries situated along the west coast of India, has been analysed. The study was carried out using remotely sensed data, obtained from the Ocean Colour Monitor (OCM) on board the Indian Remote Sensing satellite - P4, together with in situ data during the period January to December 2005. Satellite retrieval of CDOM absorption was carried out by applying an algorithm developed for the site. A good correlation (R=0.98) was obtained between satellite derived CDOM and in situ data. Time series analysis revealed that spatial distribution of CDOM has a direct link with the seasonal hydrodynamics of the estuaries. The effect of remnant fresh water on CDOM distribution could be analysed by delineating a plume in the offshore region of the Zuari estuary. Though fresh water flux from terrestrial input plays a major role in the distribution of CDOM throughout the Mandovi estuary, its role in the Zuari estuary is significant up to the middle zone. Other processes responsible for feeding CDOM in both the estuaries are coastal advection, in situ production and resuspension of bottom settled sediments. The highest value of a CDOM(440) was observed in the middle zone of the Mandovi estuary during the post-monsoon season. The relation between a CDOM(440) and S (spectral slope coefficient of CDOM) could differentiate CDOM introduced in to estuaries through multiple sources. The algorithm developed for the Mandovi estuary is S=0.003 a CDOM(440) -0.7091 while for the Zuari estuary, S=0.0031 a CDOM(440) -0.777, respectively

Satellite Coastal and Oceanographic Research Inter-comparison Exercise (SICOME)

INCOIS is coordinating Satellite Coastal and Oceanographic Research (SATCORE) project SATCORE programme since XIth plan with an aim of long-term measurements of bio-optical properties in the Indian coastal waters. The principal aim of these measurements is continuous measurement of in situ bio-optical data for validation of existing ocean color algorithms, improvement, development of new bio-optical algorithms in coastal waters of India. INCOIS had identified 12 time series sampling transects along east and west of India for continuous measurement of bio-optical parameters. Regular in situ sampling and analysis at time series stations are carried out by sub-projects sanctioned under SATCORE program to various Research and Academic &D Institutions: Junagadh Agricultural University (Off Okha), NIO, Goa (Off Goa), Goa University (Off Goa), Mangalore University (Off Mangalore), CIFT, Kochi (Off Kochi), Annamalai University (Off Parangipettai), IIT Madras (Off Chennai), Andhra University (Off Visakhapatnam), CSBoB, Andhra University (Off Visakhapatnam), Berhampur University (Off Gopalpur), Jadavpur University (Off Frazergunj), CARI (ICAR) (A & N Islands). To ensure the accuracy of the parameters measured at vasrious laboratories at different time-series locations, Satellite Coastal and Oceanographic Research-Inter-comparison Exercises (SICOME) were conducted during 2014 and 2015. During SICOME samples of Optically Active Substances i.e chlorophyll-a (chl-a), coloured dissolved organic matter (CDOM) and total suspended matter (TSM) were collected from one location. The master samples were immediately analyzed and duplicate samples were sent to different SATCORE laboratories. All the fluorometers were calibrated with teh standards for chlorophyll-a, Chromophoric Dissolved Organic Matter (CDOM) and Turbidity. All five Radiometers were also operated simultaneously to estimate the instrument bias. The document provides results of the instrument and analytical bias for same samples analyzed at various SATCORE laboratories so as to maintain the data quality for international standard

Imprint of cyclone Phailin on water quality of Chilika lagoon

The very severe cyclonic storm Phailin, a category-5 hurricane, was developed over the north of Andaman and Nicobar Islands on 9 October 2013. Subsequently, it propagated towards north-northwest and made landfall at the Gopalpur coast, Odisha on 12 October1. Chilika lagoon, the largest brackish water lagoon in Asia, is in close proximity to Gopalpur

Cyclone Phailin enhanced the productivity following its passage: Evidence from satellite data

Over the past decade (2002–2013) the Bay of Bengal has experienced 12 cyclones and 27 tropical storms. The recent one was the cyclone Phailin which was equivalent to a category-5 hurricane on the Saffir–Simpson hurricane wind scale(SSHWS). The cyclonic storm developed over the north of Andaman and Nicobar Islands on 9 October 2013. Subsequen tly,it propagated towards north-northwest and made a landfall at the Gopalpur coast of south Odisha on 12 October

Fundamentals of ocean colour remote sensing

Remote sensing refers to collection of information about an object without being in direct contact with the object. Remote sensing aids in measuring remote areas which are inaccessible by any other means and offer less expense than in-situ measurements. Remote sensing facilitates creation of long time series and extended measurement. This has the advantage that several parameters can be measured at same time and satellite-based remote sensing measurements allow global observations. Remote sensing has its own advantages and disadvantages. The limitation includes indirect measurements of large areas which are not of interest to the user. The automated instrument degradation creates retrieval errors and are affected by several factors/processes, and not only by the object of interest. Additional assumptions and models are needed for the interpretation of the measurements and before using these models in oceanographic studies, it is extremely important to validate the performance of the various ocean colour algorithms with in-situ observations (Swirgon et al., 2015)

Hoe lawaaierig is de oceaan?

Onder de zeespiegel is het nooit stil. De mens – wat dacht je – drukt er zijn stempel. Al gaat de natuur niet vrijuit. En het geluid zit werkelijk overal. Zelfs in de Marianentrog, met 11 km het diepste punt van de wereldzeeën, is geluid alomtegenwoordig. Aardbevingen, walvissen, schepen en orkanen creëren er een kakafonie van geluiden. In wat volgt gaan we op zoek naar het voorkomen en de invloed van onderwatergeluiden in de oceaan. We zoeken een antwoord op de vraag: hoe natuurlijk is het geluid in de oceaan, wat betekent dit voor zeedieren en wat kunnen we doen om extra geluidvervuiling te voorkomen of te milderen

Distribution of hydro-biological parameters in coastal waters off Rushikulya Estuary, East Coast of India: A premonsoon case study

The hydro-biological parameters of coastal waters off Rushikulya estuary was investigated during premonsoon 2011. Important hydro-biological parameters such as water temperature, salinity, pH, DO, NO2, NO3, NH4, PO4, SiO4, TSM, Chl-α, phytoplankton and zooplankton were measured during the present study. Temperature established a strong positive correlation with salinity and pH during the present study. Chl-α found in positive relation with NO3, SiO4 and TSM. Analysis of variance revealed significant monthly variation in pH, salinity and TSM. Significant station wise variation was observed in DO and most of the nutrients i.e., NO3, NH4, PO4, SiO4. A total of 119 species of phytoplankton were identified of which 84 species are of diatoms, 22 species of dinoflagellates, 7 species of green algae, 5 species of cyanobacteria (blue green algae) and 1 species of cocolithophore. Phytoplankton abundance varied between 25543 (Nos. L-1) and 36309 (Nos. L-1). Diatoms dominated the phytoplankton community followed by dinoflagellates in all the months. Diatoms contributed to 82-89 of the total phytoplankton population density whereas dinoflagellates contributed to 6-12. The regression between Chl-α and phytoplankton abundance resulted with weak relation (R2 = 0.042). Zooplankton fauna composed of 134 species of holoplankton and 20 types of meroplankton were encountered during the study period. Zooplankton population dominated by copepod during all months and accounted for 74 to 85 to the total zooplankton. The population density ranged from 6959 to 35869 Nos./10 m3. Analysis of variance explained no significant variation in total zooplankton abundance and also for different groups of zooplankton

Oil pollution in Chilika lagoon: An anthropogenic threat to biodiversity

Chilika lagoon is situated on the east coast of India and is spread over three districts of Odisha, namely Puri, Khordha and Ganjam. The water spread area varies between 1165 and 906sq.km during monsoon and summer respectively. It is a hot spot for biodiversity, and the largest wintering ground for migratory avian guests on the Indian sub-continent

Biological implications of cyclone Hudhud in the coastal waters of northwestern Bay of Bengal

A very severe cyclonic storm, Hudhud, equivalent to a category-4 hurricane on the Saffir–Simpson hurricane wind scale (SSHWS), originated in the Andaman Sea on 6 October 2014. The cyclone propagated west-northwestward and made landfall near Visakhapatnam, northern coast of Andhra Pradesh on 12 October 2014. The study area, Gopalpur (southern coast of Odisha) was in the active influence zone of Hudhud and in close proximity (~260 km north) to the landfall point (Figure 1). This region is an important mass nesting rookery for vulnerable olive ridley sea turtles, which aggregate for breeding in the coastal waters off Odisha from November to May1. This region is also identified as a time-series station under the SATellite Coastal and Oceanographic REsearch (SATCORE) programme coordinated by the Indian National Centre for Ocean Information Services (INCOIS); it is being monitored since 2009

Spring inter monsoon algal blooms in the Eastern Arabian sea: Shallow marine encounter off Karwar and Kumbla Coast using a Hyperspectral radiometer

We encountered the presence of algal blooms in the shallow coastal waters; typical of case II conditions off Karwar (Karnataka) and Kumbla (Kerala), eastern Arabian Sea during the Inter Monsoon. The algal blooms are Trichodesmium species and appear in shades of brown strands and tufts representing T. Erythraeum. Sites of the algal blooms depict a high spectrophotometric surface chlorophyll-a value ranging from 32- 39 mgm-3 and sea surface area surrounding the bloom sites depict lower values of chlorophyll-a (1-3 mgm-3). In-situ Hyperspectral radiometer measurements depict the existence of Chlorophyll Maxima at various depths (3.0-37.31 ug/l) representing the blooms along with their surface appearance. Contrary to the Karwar blooms that are dense, the blooms at Kumbla were dispersed and scantly distributed on the surface waters. Our sea-truth data on mean Sea Surface Temperature of Karwar (30.61 °C) that simulates the Kumbla (30.34 °C) scenario and the mean salinity of Kumbla was 35.86psu, and that of Karwar that is slightly elevated (35.40psu), suggests that SST and salinity probably do not either directly enhance or provide an environment for the eterioration of algal blooms