NOPR Collection:

Trends of variations in the mean annual surface temperature and salinity anomalies in the Southern Hemisphere

2021-06-04T08:44:31Z

Title: Trends of variations in the mean annual surface temperature and salinity anomalies in the Southern Hemisphere Authors: Maiyza, I A; El-Geziry, T M; Maiyza, H I Abstract: Using linear and quadratic regression approaches, the present work aims at drawing the general long-term behaviour of the mean annual surface temperature and salinity anomalies (MASTA & MASSA) within the South Atlantic and the South Pacific Oceans. The dataset covers 103 years (1911-2013) within the former, while it covers 155 years (1859-2013) within the latter ocean. The MASTA variations in the two southern oceans reflect opposite linear and quadratic trends of variations. The linear trends of MASSA are also in contrast. On the other hand, the quadratic regression, reflecting a cyclic trend of variation in the MASSA, has the same parabolic form in the two basins but with different years of maximum occurrence. The decreasing trends in the MASSA of Pacific Ocean may be attributed to the ice melting process, the interannual variability of evaporation and the amount of precipitation over the Pacific than on the Atlantic. Page(s): 271-276

A case study of coastal currents in relation with tides and winds in a tropical coastal waters of Vengurla, West Coast of India

2021-06-04T08:42:21Z

Title: A case study of coastal currents in relation with tides and winds in a tropical coastal waters of Vengurla, West Coast of India Authors: Rasheed, K; Dora, G Udhaba; Noujas, V; Kankara, R S; Manikandan, M; Sathish, S; Arockiaraj, S Abstract: Coastal currents consist of wind-driven, tidal, surface wave and geostrophic flows. These currents have a major role for nearshore sediment transport, but the measured data availability on coastal currents for the Indian coast is relatively less. This study analyze the variability of coastal currents along with the tides at nearshore and offshore waters during two different seasons (fag end of summer monsoon and initial stage of pre-monsoon) at Vengurla, west coast of India. Results of this study exhibited that the tides at Vengurla are mixed semi-diurnal dominated by solar constituent during summer monsoon (September to October); whereas the lunar constituents dominates during pre-monsoon (February to March). The nearshore current was dominated by the westward flow (sluggish current) during monsoon and south eastward flow during pre-monsoon, whereas the offshore flow (strong current) showed seasonality. At offshore, southerly current dominated during summer monsoon, whereas the northerly current played a major role during pre-monsoon. The current profile analysis at offshore revealed that the gradation of strong current at the surface to the sluggish nature of currents at the bottom and were comparatively higher during summer monsoon than pre-monsoon periods. This study revealed a complex pattern among winds, tides and currents at offshore. Page(s): 277-286

The effects of elevated-CO2 and UVR on photosynthetic performance and nitrate reductase activity of Ulva flexuosa Wulfen 1803

2021-06-04T08:40:00Z

Title: The effects of elevated-CO2 and UVR on photosynthetic performance and nitrate reductase activity of Ulva flexuosa Wulfen 1803 Authors: Yildiz, G Abstract: After the industrial revolution, increasing anthropogenic CO₂ emission causes a number of changes in seawater. These changes are known as ocean acidification and affect the seaweeds in various ways. Therefore, this study is aimed to determine the ecological succession of Ulva flexuosa Wulfen 1803 in future predicted CO₂-induced low pH conditions alone and in combination with naturally relevant ultraviolet radiation (UVR). For this purpose, acidification experiments with and without UVR were conducted on U. flexuosa from the Mediterranean coast, and important physiological features of algae was investigated. In this study, the Fv/Fm ratios of U. flexuosa ranged from 0.718±0.01 to 0.754±0.009. While rETRmax values of samples exposed to elevated-CO₂ were measured between 112.13 – 151.93 µmol e^-m^-2s^-1, it was determined between 111.7 – 158.4 µmol e^-m^-2s^-1in samples exposed to ambient sea water. According to our results, increased CO₂ concentration in seawater did not improve the photosynthetic efficiency of U. flexuosa. However, when the specimens were exposed to elevated-CO₂, nitrate reductase activity of U. flexuosa was declined drastically. According to the results, it is suggested that the elevated CO₂ may regulate the nitrogen preference of U. flexuosa. Besides, the data also show that U. flexuosa was not sensitive to UVR. Page(s): 287-295

Unprecedented report of the calanoid copepod Acartiella faoensis Khalaf, 1991 from the estuarine waters of the lower-middle stretch of river Hooghly, West Bengal, India

2021-06-04T08:17:03Z

Title: Unprecedented report of the calanoid copepod Acartiella faoensis Khalaf, 1991 from the estuarine waters of the lower-middle stretch of river Hooghly, West Bengal, India Authors: Mukherjee, A; Sanyal, P; De, T K; Mukhopadhyay, S K Abstract: Acartiella faoensis, previously known as Acartia (Acartiella) faoensis, is a calanoid copepod which was observed during a biodiversity survey, during July-August of 2018, on the lower-middle stretch of the Hooghly River (upper reaches of Hooghly estuary). The species is reported for the first time from the aforementioned locality as well as anywhere from the eastern India and perhaps the entire country. Individuals belonging to both the sexes have been collected and studied. The observed species is native to Khour-Abdullah and Khor Al-Zubair waters of the Northwestern Gulf of Arabia as evidenced by earlier works and its appearance in the presently reported location is of great ecological significance. This account deals with the description of the species using compound microscopes and drawings made by using camera-Lucida, to be used as reference in future works. Page(s): 296-301