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Seasonal assessment of the trophic status in the coastal waters adjoining Tuticorin harbor in relation to water quality and plankton community in the Gulf of Mannar, India

Sathishkumar Rengasamy Subramaniyan, Sundaramanickam Arumugam, Mohanty Ajit Kumar, Sahu Gouri, Ramesh Thangavelu, Balachandar Kumar, Nithin Ajith, Surya Parthasarathy, Silambarasann Krishna

Oceanologia

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2022

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No. 64 (4)

749--768

EN

Seasonal variations in hydrography, trophic status, and plankton community structure were studied along the Tuticorin coastal waters (TCWs) in the Gulf of Mannar (GoM). Samples were collected in 2015 and 2016 to analyze physico-chemical (temperature, pH, salinity, suspended particulate matter (SPM), dissolved oxygen (DO), nutrients, etc.) and biological parameters (chlorophyll-a, phytoplankton, and zooplankton). The trophic index (TRIX) and eutrophication index (EI) were calculated to describe the eutrophication status of TCWs. Temperature, pH, salinity, DO, and SPM showed seasonality due to the impact of the northeast monsoon. A massive bloom of Trichodesmium erythraeum was observed, with a visible impact on water quality and the plankton community. The cluster and principal component analysis indicated the bloom event as a distinct phenomenon. ANOVA results showed significant seasonal variations rather than spatial variations. According to the trophic indices, the area had a low trophic level in 2015 and a high trophic level in 2016. The Tuticorin inshore waters had the highest TRIX and EI values during the dominance of cyanobacteria bloom in the post-monsoon 2016. The trophic indices had a positive relationship with phytoplankton abundance but showed an inverse relation with zooplankton abundance. The overall range of the TRIX index (3.18–5.96) indicated that the environment was oligotrophic to eutrophic, and EI values (0.72–21.61) indicated that the state of coastal waters was moderate to poor. This study states that periodic monsoonal flow and frequent algal bloom events have a significant impact on the GoM coastal waters.

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Algal bloom, hypoxia, and mass fish kill events in the backwaters of Puducherry, Southeast coast of India

Mishra Pravakar, Naik Subrat, Babu P. Vipin, Pradhan Umakanta, Begum Mehmuna, Kaviarasan Thanamegam, Vashi Athan, Bandyopadhyay Debasmita, Ezhilarasan Pazhaniyappan, Panda Uma Sankar, Ramana Murthy Mallavarapu Venkata

Oceanologia

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2022

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No. 64 (2)

396--403

EN

The Chunnambar backwater of Puducherry experienced changes in water quality over a period. The most significant impact was the sudden mass fish kill event coincided with the Pseudo-nitzschia bloom. On 25th September 2019, a mass fish kill event was reported, i.e. about a 0.25 metric ton (MT) floating on the water surface. On 29th September 2019, a much larger (∼1 MT) than the earlier incident had occurred. Sampling was carried out to assess the causes thereof. The results indicate that high organic matter and bacterial loads accumulated in the water and sediment due to the closure of the river mouth for an extended period. High ammonia (61.4 µM) and phosphate (6.2 µM) levels attributed to eutrophic conditions in the water column and hypoxemia due to low dissolved oxygen (1.62 mg/L at St.1 and 2.4 mg/L at St.5) and algal bloom were the proximate cause of these sudden fish kills. We recommend periodic dredging to facilitate proper water exchange between the backwater and the sea.

3

Response of coastal phytoplankton to upwelling induced hydrological changes in the Alappuzha mud bank region, southwest coast of India

Madhu Nikathithara Velappan, Anil Peariya, Meenu Paul, Gireeshkumar Thundiyil Raju, Muraleedharan Kallungal Ravunnikutty, Rehitha Thekkendavida Velloth, Dayana Mathew, Vishal Chazhikulam Rajan

Oceanologia

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2021

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No. 63 (2)

261--275

EN

The response of phytoplankton community to the co-existing events of coastal upwelling and mud banks in the nearshore waters of Alappuzha (15 m depth), located in the southwest coast of India from April to November 2016, is described based on size-fractionated phytoplankton biomass (chlorophyll a), primary production and community composition. The study region exhibited well-distinct spatio-temporal hydrological changes because of the influence of wind-driven coastal upwelling, prevalent during the southwest monsoon (SWM) period. However, the formation of mud banks, in addition to coastal upwelling, was observed at station M2, which facilitated the substantial increase of water column turbidity and inorganic nutrients (ammonium, phosphate, and silicate) during and after the peak SWM period compared to the non-mud bank reference stations (M1 and M3). The prevailing hydrological changes were complemented the corresponding phytoplankton productivity patterns, in which profound domination of nanophytoplankton (2-20 µm) chlorophyll a and primary production was observed throughout the study region, irrespective of seasons. The SIMPER analysis, based on phytoplankton (mostly >20 µm) species composition data (microscopy), revealed the formation of certain characterizing species, mainly comprised of diatoms and dinoflagellates. The consistent predominance of the nanophytoplankton, established under variable hydrological scenarios, showed that the inorganic nutrient (specifically ammonium) availability was instrumental in defining the widespread growth of nanophytoplankton community compared to the prevailing light levels. The present study thus revealed that even the small-sized phytoplankton community could survive in the nutrient-enriched coastal waters, characterised by the co-existing upwelling and mud banks.

4

Taxonomic classification of algae by the use of chlorophyll a fluorescence

Szymański N., Dąbrowski P., Zabochnicka-Świątek M., Panchal B., Lohse D., Kalaji H. M.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2017

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Vol. 26, No. 4

470--480

EN

Natural water reservoirs are very important ecosystems thus they should be under continuous monitoring and protection. In water of low quality, the algal blooms develop develops vastly. The knowledge of algal species composition is necessary for understanding this process. There are a few traditional group-specific methods of microalgae classification, but they are often labour-intense and time-consuming. Moreover, the samples must be prepared and/or collected before getting any results. Non-invasive chlorophyll fluorescence analysis offers an alternative approach and potentially allows in situ estimation of algal concentration. In this work the fluorometric methods to estimate algae content in water and to differentiate algal populations is presented.

5

Massive occurrence of the alien invasive species Pleodorina indica (Volvocales, Chlorophyta) in a reservoir located in urban areas of Central Poland

Knysak P., Żelazna-Wieczorek J.

Oceanological and Hydrobiological Studies

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2017

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Vol. 46, No. 1

116--122

EN

Pleodorina indica (Iyengar) H. Nozaki is a rare species from the Volvocaceae family (Chlorophyta, Volvocales), which naturally occurs in aquatic ecosystems of the tropical climate zones. This is the first record of this species I in Poland in a flow-through man-made reservoir on the Olechówka River in Łódź. The sampling site of P. indica in Łódź is the northernmost site in Europe. Among other records, the species has been also reported from Austria in 1996 and the Czech Republic in 2003. During the summer of 2015, abundant occurrence of this species was observed at the sampling site, at extremely high air and water temperatures. Physical parameters in the reservoir and the duration of the P. indica bloom were measured. In addition, morphological features of the species were observed with the use of light and confocal microscopy.

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Attempts to eliminate cyanobacterial blooms in Lake Łasińskie

Wiśniewski R.

Environment Protection Engineering

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2002

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Vol. 28, nr 1

15-25

EN

In the years 1998-2001, investigations of Łasińskie Małe and Zamkowe Lakes were conducted. The two lakes are shallow and very susceptible to degradation. Very high trophic level, high pollution level and recurring annual cyanobacterial blooms have caused that lakes have not been recreationally used since 1994. The aim of investigations was to work out the programme of reservoirs restoration. In order to test the methods, in June 1998 trials of cyanobacterial bloom inhibition in natural, isolated bath area were undertaken. Main measures were exposure of barley straw bales and addition of FeCl3. After one month considerable changes in the composition of phytoplankton were recorded. The drastic slump in the biomass of Aphanizomenon flos-aquae and domination of eucariotic algae were observed. Water transparency substantially increased. The measures were repeated and the method was modified and developed in the successive years. The main causes of temporarily worse effects were damage of isolating barriers in the bathing area and seasonal increase in BOD5 caused by influx of fine-grained organic suspension from unidentified source.

PL

W latach 1998-2001 prowadzono badania na Jeziorze Łasiński Małym i Jeziorze Zamkowym. Obydwa jeziora są płytkie i bardzo podatne na degradację. Powtarzające się corocznie intensywne zakwity sinicowe stanowią główną przyczynę ograniczonego wykorzystywania rekreacyjnego obydwu zbiorników. Celem badań było opracowanie programu rekultywacji zbiorników. Aby przetestować zaproponowane metody, w czerwcu 1998 r. Podjęto zabiegi zmierzające do ograniczenia zakwitu sinic w rejonie odizolowanego, naturalnego kąpieliska miejskiego. Sprowadzały się one głównie do zastosowania zarówno balotów słomy jęczmiennej, jak i chlorku żelaza. Po miesiącu odnotowano znaczne zmiany w składzie fitoplanktonu. Stwierdzono drastyczny spadek biomasy Aphanizomenon flos-aquae i dominujący udział glonów eukariotycznych. Istotnie wzrosła przezroczystość wody. Prace w rejonie kąpieliska powtarzano w następnych latach, modyfikując i wzbogacając metodę. Powodem gorszych okresowo efektów, zwłaszcza w 2001 r., było rozszczelnienie osłony izolującej kąpielisko i wzrost BZT5 spowodowany dopływami drobnej zawiesiny organicznej z niezidentyfikowanego źródła.