Submarine Groundwater Discharge (SGD) and Seawater Intrusion (SWI) are two contrary hydrological processes that occur across the land-sea continuum and understanding their nature is essential for management and development of coastal groundwater resource. Present study has attempted to demarcate probable zones of SGD and SWI along highly populated Odisha coastal plains which is water stressed due to indiscriminate-exploitation of groundwater leading to salinization and fresh groundwater loss from the alluvial aquifers. A multi-proxy investigation approach including decadal groundwater level dynamics, LANDSAT derived sea surface temperature (SST) anomalies and in-situ physicochemical analysis (pH, EC, TDS, salinity and temperature) of porewater, groundwater and seawater were used to locate the SGD and SWI sites. A total of 340 samples for four seasons (85 samples i.e., 30 porewater, 30 seawater and 25 groundwater in each season) were collected and their in-situ parameters were measured at every 1-2 km gap along ~ 145 km coastline of central Odisha (excluding the estuarine region). Considering high groundwater EC values (> 3000 μS/cm), three probable SWI and low porewater salinities (< 32 ppt in pre- and < 25 ppt in post-monsoons), four probable SGD zones were identified. The identified zones were validated with observed high positive hydraulic gradient (> 10 m) at SGD and negative hydraulic gradient (< 0 m) at SWI sites along with anomalous SST (colder in pre- and warmer in post-monsoon) near probable SGD locations. This study is first of its kind along the Odisha coast and may act as initial basis for subsequent investigations on fresh-saline interaction along the coastal plains where environmental integrity supports the livelihood of coastal communities and the ecosystem.

Patterns in parasite diversity are shaped by their environmental and ecological settings, and to better understand their interactions with hosts and the corresponding biology, it is crucial to understand these context-dependent patterns. To achieve this, we use cymothoid isopods, an important group of fish parasites, to test a long-standing hypothesis about parasite diversity and prevalence pattern: whether semi-enclosed water bodies allow low diversity and high prevalence of parasitic isopods. Specifically, we compare these patterns between Chilika lagoon (Odisha, India), a semi-enclosed water body, and the adjoining Odisha coast (India). Our finding reveals that the semi-enclosed Chilika lagoon has a considerably lower diversity of parasitic isopods than its adjoining open sea along the Odisha coast. Additionally, the parasitic isopod infection levels in Chilika lagoon are noticeably higher, and isopod assemblage is less even than those in coastal waters along the Odisha coast. Our results support the hypothesised association between enclosed water bodies, parasite diversity, and host prevalence and contribute to an enhanced comprehension of the ecology of parasitic isopods in distinct marine environments.

Climate change-mediated rise in sea level and storm surges, along with indiscriminate exploitation of groundwater along populous coastal regions have led to seawater intrusion. Studies on groundwater salinization and heavy metal contamination trends are limited. Present study investigated the heavy metal contamination, associated risks and provided initial information on the impacts of groundwater salinization on heavy metals along the coastal plains of Odisha, India. Total 50 groundwater samples (25 each in post- and pre-monsoon) were collected and analysed. Concentrations of Fe (44%), Mn (44%), As (4%) and Al (4%) in post-monsoon and Fe (32%), Mn (32%), As (4%), B (8%) and Ni (16%) in pre-monsoon exceeded Bureau of Indian Standards (BIS) drinking water limits. High concentrations of heavy metals (Fe, Sr, Mn, B, Ba, Li, Ni and Co) and high EC (>3000 μS/cm) indicated that the groundwater-seawater mixing process has enhanced the leaching and ion exchange of metallic ions in central part of the study area. Multivariate statistical analysis suggested leaching process, seawater intrusion and agricultural practices as the main heavy metal sources in the groundwater. 4% of samples in post- and 16% in pre-monsoon represented high heavy metal pollution index (HPI). Pollution indices indicated the central and south-central regions are highly polluted due to saline water intrusion and high agricultural activities. Ecological risks in the groundwater systems found low (ERI <110) in both seasons. Children population found more susceptible to health risks than adults. Hazard index (HI > 1) has shown significant non-carcinogenic risks where Fe, Mn, As, B, Li and Co are the potential contributors. Incremental lifetime cancer risk (ILCR >1.0E-03) has suggested high carcinogenic risks, where As and Ni are the major contributors. The study concluded that groundwater salinization could increase the heavy metal content and associated risks. This would help policymakers to take appropriate measures for sustainable coastal groundwater management.

Odisha\'s coastline supports various development activities that are critical to the state and national economy, such as oil and gas, ports and harbors, power plants, fishing, tourism, and mining that continues to not only detriment the coastal ecology but also affect the overall shoreline morphodynamics. The morphological changes are complicated processes involving both natural and human-induced drivers, but it is critical to understand how recent development activities further impact beach morphodynamics and shoreline dynamicity. The study analyzes the overall shoreline morphodynamics in response to the recent development of port and other related infrastructure for annual and decadal scale using two-dimensional (2-D) shoreline changes along with detailed 3-D beach profile volumetric changes for different studied zones along the Gopalpur coast. The results reveal that nearly all studied zones of the Gopalpur shoreline, Zone-4 (EPR = -05.64 m a-1 and LRR = -04.25 m a-1), Zone-3 (EPR = -04.51 m a-1 and LRR = -07.01 m a-1) and Zone-1 (EPR = -2.85 m a-1 and LRR = -01.46 m a-1), experienced erosion between 2010 and 2020 except Zone-2 (EPR = 24.31 m a-1 and LRR = 25.96 m a-1), which showed overall sign of deposition. The interannual shoreline analysis depicted that Zone-1 (tourist beach area) remained almost stable, Zone-2 (south of the breakwater of Gopalpur Port) showed accretion trends, Zone-4 (north side of the port) dominantly showed an erosion pattern, whereas Zone-3 (port area) showed a high level of uncertainty in the context of erosional or deposition trends. Calculated volumetric loss along the surveyed 3-D beach profiles supports these 2-D changes for all the studied zones. The results showed substantial changes in coastal morphodynamics in different studied zones of the Gopalpur region and severe erosion along its northern segment of the constructed coastal infrastructure. These findings can potentially promote effective coastal zone management and prevent further deterioration along the Gopalpur coast in future.

The present record of different developmental stages of the parasite Mothocya renardi (Bleeker, 1857) and gravid female of Mothocya collettei Bruce, 1986 from different individuals of same host Strongylura leiura (Bleeker, 1850) collected from Bay of Bengal, Gopalpur-on-Sea, Odisha, India are the first record of these parasites from the northern part of east coast of India. The record of Mothocya collettei from the host Strongylura leiura is the first host record for this parasite.

The prevalence of microplastics along the coastal habitats has become a global concern owing to the increased input of plastic debris from multiple sources. The present study is the first of its kind to examine the prevalence and distribution of microplastics in Odisha coast. The average microplastic abundance in the nine stations along Odisha coastal beach is 258.7 ± 90.0 particles/kg of beach sediment. Among the stations sampled, Swargadwara was reported with the highest microplastic abundance of 378.3 ± 39.7 particles/kg of beach sediment andAbhayachandpurwas found with the lowest number of 153.3 ± 27.3 particles/kg. Different types of microplastics varying in color, size, and shape were encountered in the study. From the Raman spectroscopic analysis, twelve types of polymers including High Density Polyethylene, Polystyrene, Polyvinyl chloride, and acrylonitrile copolymer were identified.

Identification of fish species have so far been carried out mostly by classical morpho-taxonomy. In the present study, however, an attempt has been taken to identify two species of fishes Ulua mentalis and Pinjalo pinjalo of order Perciformes which happens to be the first record in Odisha coast Bay of Bengal, India during the year 2015, using DNA barcoding technique for reconfirmation over conventional morpho-taxonomy. During recent past, study of molecular-taxonomical profile of mitochondrial DNA in general and Cytochrome Oxidase subunit I (COI) gene in particular has gained enormous importance for accurate identification of species. In the present study, the partial COI sequence of Ulua mentalis and Pinjalo pinjalo were generated. Analysis using the COI gene produced phylogenetic trees in concurrence with other multi gene studies and we came across the identical phylogenetic relationship considering Neighbor-Joining and Maximum Likelihood tree. Moreover, these molecular data set further testified in Bayesian framework to reevaluate the exact taxonomic groupings within the family. Surprisingly, Ulua mentalis and Pinjalo pinjalo seems to be closely related to their sister taxa.