Effect of an oil spill from M V Sea Transporter on intertidal meiofauna at Goa,India

Short and long term effects of a fuel oil spill from a grounded ship "M V Sea Transporter" on meiofauna of a sandy beach of central West Coast of India were investigated. A significant reduction in the absolute abundance of meiofauna was observed immediately after 3 days of spillage particularly at Sinquerim beach, the site of spillage. The reduction was most pronounced in density of nematodes and harpacticoid copepods, which were the most dominant groups. Long-term response showed no apparent oil-induced changes at major taxa levels. The population density improved considerably after the cessation of monsoons with a parallel decrease in petroleum hydrocarbon concentration in the sediment. Nematodes recovered more quickly than benthic copepods. No evidence for this could be due to reproductive dynamics in meiobentos. Although the effect of the oil on meiofauna could be seen initially it could not be proved conclusively on a long-term basis. The effects of the oil spill were confounded with seasonal monsoon effects and beach dynamics. The nematode:copepod ratio and the index of trophic diversity (ITD) were inadequate for detecting oil pollution effects. Therefore it may be concluded that in the presence of other environmental factors acting strongly, the effects of oil on meiofauna was strong but of a temporary nature.     

2D and 3D rockfall hazard analysis and protection measures for Saptashrungi Gad Temple,Vani, Nashik,Maharashtra – A case study

The Saptashrungi gad temple (SGT) situated on basaltic hills belongs to Deccan volcanic of Upper Cretaceous to Lower Eocene, is one among the 51 Shakti Peeths and most holy place for pilgrims. Rockfall is a major problem in the past and causing danger to the lives of the villagers settled at the toe of the SGT hill as well as the pilgrims who perform parikrama along the tracks. On the evening of 16 April 2011, an old woman died due to rockfall at SGT hill when she was performing parikrama, moreover, two persons got injured during the deliverance process of this old woman from the continuous rockfall activity. The problem of rockfall could be linked to rainfall, jointing, weathering, man-made or the compounding of all. In this research, the rockfall hazard analysis at SGT hill is assessed using both 2D and 3D rockfall programs along the two parikrama paths: Parikrama Path 1 (or the Badi Parikrama Path ‘BPP’), and Parikrama Path 2 (or the Chhoti Parikrama Path ‘CPP’). Also, the study area of the SGT hill has been divided into eight zones (Zone#01 to Zone#08), based on field observations, orientations of joint sets and hill slope faces and eighteen topographic profiles (AA' to RR') have been taken from these eight zones for rockfall analysis. A detailed topographic survey along with field investigation has been carried out along the temple for ascertaining the nature of rock, discontinuity orientations, and slope geometry. DEM has been generated using topographic profile in ArcGIS to facilitate the 3D rockfall analysis. Maximum rock block sizes are taken into the analysis and run-out distance, bounce height, kinetic energy and velocity of the basaltic blocks are evaluated separately. Based on the analyzed data, the rockfall hazard zone map has been prepared and site having potential rockfall risks have been identified. Finally, wire/net meshing has been proposed after removal of unstable blocks as a stabilization and protection measures.It is worth mentioning here that for the first time rockfall hazard assessment was made in such detail for a site. Suggestions made are implemented by the State Government for the protection of the temple as well as the life of pilgrims performing the parikrama from the rockfall.     

The probability distributions and fractal dimension of sunspot cycles associated with ENSO phenomena

Various methods have been used to secure the certainty of significant relations among the sunspot cycles and some of the terrestrial climate parameters such as temperature, rainfall, and ENSO. This study investigates the behavior of ENSO cycles and mean monthly sunspot cycles. Sunspot cycles range from 1755 to 2016 whereas, ENSO cycles range from 1866 to 2012. In this regard, the appropriateness of distributions is investigated with the help of Kolmogorov-Smirnov D, Anderson-Darling, and chi-square tests. It is found that most of the sunspot cycle follows generalized Pareto distribution whereas, generalized extreme value distribution was found appropriate for ENSO cycles. Probability distribution is used to analyze the behavior of each sunspot cycle and ENSO cycle separately. Probability distribution indicates the tail behavior of each cycle; tail explored correlation cycles. Furthermore, self-similar and self-affine fractal dimension methods are used to compute Hurst exponents to determine the persistency of the available data. Fractal dimension has an ability to study the complexity involved in sunspot and ENSO cycles. The fractal dimension and Hurst exponent describe persistency (smoothness) and complexity of data. Hurst exponent measures long-term behavior of time series, making it more helpful for forecasting. This is the measure of regularity or irregularity (chaos) of the time function in the form of their persistency or anti-persistency, respectively. Hurst exponents are computed using rescaled range analysis method and box counting methods. Both these methods are suitable for long-term forecasting. The results of this study confirm that during the period 1980–2000, ENSO cycles were very active. Simultaneously, ENSO was active for the periods 1982–1983, 1986–1987, 1991–1993, 1994–1995, and 1997–1998; these periods include two strongest periods of the century viz., 1982–1983 and 1997–1998. Sunspot cycles and ENSO cycles both were found to be persistent. Self-similar fractal dimensions exhibited a better persistency and a better correlation as compared to self-affine fractal dimension. This research is a part of a larger research project investigating the correlation of sunspot cycles and ENSO cycles, and the influence of ENSO cycles on variations of the local climatic parameters which in turn depends on solar activity changes.     

近20 a呼和浩特市城市化对植被物候的影响

了解植被物候与城市化之间的关系对于认识人类活动对生态系统的影响至关重要。基于呼和浩特市近20 a MODIS的两种植被指数数据,利用动态阈值法提取了植被物候,结合城市化指标,研究了2001—2020年呼和浩特市植被物候对城市化的响应。研究表明：森林和灌木地返青期（Start of growing season,SOS）发生较早（平均值第132 d）,但其枯黄期（End of growing season,EOS）也较早（第265 d）。SOS较晚的是耕地（第168 d）,EOS较晚的是草地（第275 d）,表明研究区木本植物SOS和EOS均早于草本植物。人造地表植被物候年际变化较大,在SOS和EOS的物候变化率分别为每10 a提前4.1 d和推迟0.7 d。此外,以人造地表比率和城乡梯度信息（即从城市核心到周边农村地区的同心环）为城市化指标,探讨了呼和浩特市中心城区植被物候对城市化的响应。研究发现SOS随人造地表比率上升而提前,EOS则出现相反的趋势。从城乡梯度上看,在特定范围内,远离城市中心SOS波动上升,即距城市中心越远植被SOS越晚,而EOS逐渐下降,即距城市中心越远植被EOS越早。总之,不同的城市化指标显示了植被物候对城市化的非线性响应。     

Geomorphic control on the formation of mixed layer clays by progressive degradation of biotite: A case study from Jutulsessen Gjelsvikfjella,East Antarctica

Eleven glacial sediment samples collected from different elevation of Jutulsessen Nunatak, Gjelsvikfjella of East Antarctica were studied for the clay mineralogical analysis using X-ray diffraction technique. The result shows prominent peak at 10, and 3.34 Å suggesting the presence of biotite possibly derived from the catchment where biotite rich granite gneisses are exposed. The detailed investigation on the shape of biotite peak of certain samples shows the signs of alteration of biotite in to a mixed layer containing tri-octahedral smectite (low charge vermiculite). The presence of mixed layer along with the biotite is found to be associated with the samples of lower geomorphic level. The progressive alteration of clay sized biotite to form a mixed layer in the lower horizons of Jutulsessen Nunatak is probably due to the periodic accumulation of melt-water during the austral summer.     

Rockfall hazard assessment at Ajanta Cave,Aurangabad, Maharashtra,India

The Ajanta caves are situated in Deccan Trap basalt and declared as one of the World Heritage Sites by UNESCO. The present study aims to investigate and understand the damage of caves and to protect the life of the visitors from the rockfall phenomenon at and around the caves. Information related to the detached rock mass/block was acquired by using Barton–Bandis model in Universal Distinct Element Code. Parameters for rockfall simulation were determined by rigorous field study and laboratory experiment and then calibrated some of the parameters by back analysis. RocFall 4.0 program has been used to calculate maximum bounce heights, total kinetic energies, and translational velocities of the falling blocks of different weights. The maximum bounce height varies from 14.0 to 19.0 m for the weight of the block size ranging from 500 to 2,000 kg, whereas the maximum velocity and maximum kinetic energy are 30.0 m/s and 917.66 kJ, respectively. Finally, the results of simulation have been used to find out the position of the barrier and its capacity to design the protection barrier. The barrier capacity was found to be 325 kJ for 2,000 kg of falling blocks at a height of 50.0 m.     

Distribution of Deep-Sea Benthos in the Proposed Mining Area of Central Indian Basin

Abstract

During the first stage of the project work on the Indian Deep-Sea Environment Experiment (INDEX), the abundance and distribution of deep-sea benthos were surveyed in the Central Indian Basin for the collection of baseline data. The deep-sea community of the sediment was characterized by a moderately high standing crop and diverse fauna. The macrofaunal component was dominated by polychaetes (100% prevalence) and peracarid crustaceans, whereas the meiofauna was dominated by nematodes and harpacticoid cope-pods. The results of this study conform to the general distribution reported elsewhere. The macrofaunal abundance showed an inverse relation to the abundance of polymetallic nodules. However, the relation between meiofaunal vertical distribution and the vertical profile of the total organic matter and total labile matter was positive.     

Restoration of Deep-Sea Macrofauna after Simulated Benthic Disturbance in the Central Indian Basin

ABSTRACT

Macrofaunal communities of the Central Indian Basin (CIB) were sampled with a spade before (June 1997), and immediately after (August 1997), and 44 months (April 2001) after a simulated benthic disturbance for polymetallic nodule mining. The average density recorded down to a sediment depth of 40 cm ranged from 89 to 799 ind·m^?2 (mean: 373 ± 221 SD; n = 12) and 178–1066 ind·m^?2 (mean: 507 ± 489 SD; n = 3) in the test and reference area, respectively. Most of the macrobenthic animals (64%) were concentrated in the upper 0 to 2 cm sediment layers, whereas, sizeable fauna (6%) inhabited the 20–40 cm sediment section and the deepest 5 cm section from 35–40 cm contributed only about 2% to the total population density. The fauna, comprised of 12 groups, were dominated by the nematodes, which constituted 54% of the total population. The macrofaunal density in the test site showed a significant increase (x:400 ind·m^?2) in the 44 months postdisturbance sampling (x:320 ind·m^?2). The population of nematodes and oligochaetes was nearly restored after 44 months, but the polychaetes and crustaceans did not reach the baseline populations measured in June 1997. The top 0–2 cm sediment layer was severely affected by the disturber, and the study suggests that physically disturbed deep-sea macrofauna may require a longer period for restoration and resettlement than normally believed.     

Response of Meiofauna to Immediate Benthic Disturbance in the Central Indian Ocean Basin

Abstract

Twenty-four stations (12 each, during pre- and postdisturbance studies) 5300 to 5330 m deep between 10°01' and 10°03'S latitude and between 75°59' and 76°02'E longitude were sampled to study the effect of benthic disturbance on the distribution of meiofauna in the Central Indian Ocean. Bottom-sampling was conducted with a box corer. Total meiofauna density ranged from 35 to 45 organisms per 10 cm² of bottom area during the predisturbance period and 21 to 32 organisms per 10 cm² during the postdisturbance period in the test and reference sites. Differences between pre- and postdisturbance study results were statistically significant (P < 0.05). Nematoda was the most abundant meta-zoan group, on an average representing >55% of the meiofaunal population. The abundance of nematodes and harpacticoid copepods as well as total meiofauna showed marked decreases during postdisturbance sampling. Vertical distribution of meiofauna in the sediment cores revealed that 75% to 90% of the metazoan population was confined to the top 2-cm layer of the sediment. Recolonization experiments suggest that harpacticoid copepods may take more time for recolonization than the nematodes and are more sensitive to the physical disturbance. These findings suggest that nematodes and harpacticoid copepods can be used as indicator organisms in recolonization experiments.