Evaluating the influence of environmental variables on the length-weight relationship and prediction modelling in flathead grey mullet, Mugil cephalus Linnaeus, 1758.

Fish stocks that are grown under diverse environmental conditions have different biometric relationships and growth patterns. The biometric length-weight relationship (LWR) is an essential fishery assessment tool, as fish growth is continuous and depends on genetic and environmental factors. The present study attempts to understand the LWR of the flathead grey mullet, Mugil cephalus Linnaeus, 1758, from different locations. The study area encompassed its distribution in the wild across freshwater location (one), coastal habitats (eight locations), and estuaries (six locations) in India to determine the relationship between various environmental parameters. Specimens (n = 476) of M. cephalus were collected from commercial catches and the length and weight of individual specimens were recorded. Monthly data from the study locations were extracted for nine environmental variables from the datasets downloaded from the Physical Oceanography Distributed Active Archive Center (PO.DAAC) and the Copernicus Marine Environment Monitoring Service (CMEMS) over 16 years (2002 to 2017) on the Geographical Information System platform. The parameters of the LWR, intercept 'a' and slope or regression coefficient 'b', varied from 0.005321 to 0.22182 and 2.235 to 3.173, respectively. The condition factor ranged from 0.92 to 1.41. The partial least squares (PLS) score scatter plot matrix indicated differences in the environmental variables between the locations. PLS analysis of the regression coefficient and environment parameters revealed that certain environment variables viz., sea surface temperature, salinity, dissolved oxygen, nitrate, and phosphate, played a positive role. However, chlorophyll, pH, silicate, and iron played a negative role in influencing weight growth across various locations. The results revealed that the M. cephalus specimens from three locations, Mandapam, Karwar, and Ratnagiri, possessed significantly higher fitness to their environment than those from the other six locations. The PLS model can be used to predict weight growth under the various environmental conditions of different ecosystems. The three identified locations are useful sites for the mariculture of this species considering their growth performance, the environmental variables, and their interactions. The results of this study will improve the management and conservation of exploited stocks in regions affected by climate change. Our results will also aid in making environment clearance decisions for coastal development projects and will improve the efficiency of mariculture systems.

Quantitative assessment of sediment delivery and retention in four watersheds in the Godavari River Basin, India, using InVEST model - an aquatic ecosystem services perspective.

Sediment export and retention are important ecosystem processes in any landscape causing soil erosion and sediment loading in waterways consequently affecting the health of aquatic habitats downstream. The present study quantifies sediment export and retention in four watersheds, viz., Hivra, Satrapur, Konta, and Jagdalpur in the Godavari River Basin, India, using Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) ecosystem service modelling tool. The  results revealed that the sediment export yields ranged from 0.75 (Hivra) to 2.77 t/ha/year (Jagdalpur). The mean deviation between modelled values and observed sediment export yield was - 11.11%, which indicated good prediction by the model. The sediment retention ranged from 16.04 (Hivra) to 101.52 t/ha/year (Konta). Most sediment export and retention occurred on cropland or shrubland land use land cover types in all four watersheds. For decision making on soil conservation, soil loss tolerance limits have been established for these watersheds. For aquatic habitats, sediment concentration is considered more important than the total annual sediment export, since water turbidity is an important determinant of water quality, and the aquatic lives therein. Therefore, the temporal distribution of rainfall and corresponding sediment export becomes important, since these two factors determine the sediment concentration as well as turbidity in the waterbody. In current study, "Precipitation Concentration Index adjusted Sediment Export Yield Index" was developed to account for the effects of the temporal rainfall distribution and its impact on sediment export. The index for four watersheds was quantified (Hivra > Satrapur > Konta > Jagdalpur), which is concordant to the turbidity values reported by respective gauge stations. Thus, the proposed index can efficiently capture the impact of temporal rainfall distribution on sediment export, and consequently its effect on water turbidity. The study revealed the potential of InVEST model to quantify the sediment export and retention in the watersheds studied. Together with the proposed index, it would help the policy makers in making informed decisions for planning conservation strategies for aquatic biodiversity.

Phenotypic variation of Chitala chitala (Hamilton, 1822) from Indian rivers using truss network and geometric morphometrics.

Chitala chitala (Hamilton, 1822) is an economically important food fish species occurring throughout Indian rivers, which also has ornamental value. This study focuses on morphological variations in C. chitala from seven river basins across India namely; Son, Tons, Ken, Brahmaputra, Ganga, Gomti and Gandak. A truss network was constructed by interconnecting nine landmarks to generate 36 morphometric variables extracted from digital images of specimens sampled from the study locations. Transformed truss measurements were subjected to principal component analysis (PCA), canonical discriminant function analysis (CDFA) and discriminant analyses of principal components (DAPC). DAPC function coefficients performed much better in capturing the variation pattern and discrimination between the rivers which was not achieved using CDFA. Eight truss variables were identified with significant and highest loading for truss variables on principal components and coefficients on discriminant function from DAPC contributing to maximum variation between the rivers. Performance graph and functional distribution of identified truss variables clearly indicated distinction between the rivers. Thin plate spline analysis and procrustes shape analysis further showed the variation in morphology between specimens across the rivers. The significant parameters differentiating specimens from different rivers were linked to dorsal fin origin, the base of the pectoral fin and the perpendicular point on the anal fin from the dorsal fin origin. Variation in the hydrodynamics of the rivers studied might be possibly affecting the fin kinematics and consequently leading to adaption seen as phenotypic variation in C. chitala. The results showcased in the present study shall help in better understanding of intra-specific diversity which is significant for management and conservation of a species.

Integrative taxonomy-based discovery of Dussumieria modakandai sp. nov. from India.

This study is based on integrative taxonomy and reports a new fish species Dussumieria modakandai sp. nov. from India. The new species differs from three valid species within the genus by a combination of characters such as longer maxilla (9.1%-9.9% standard length vs. 8.7% in Dussumieria elopsoides, 6.3%-8.5% in Dussumieria acuta) and one or two rows of small conical teeth on palatine (vs. several rows in D. elopsoides and Dussumieria albulina). It also differs by the absence of longitudinal striae on the posterior side of body scales (vs. presence in D. acuta and D. albulina) and the absence of parasphenoid teeth (vs. presence in D. acuta). The maxilla length of D. modakandai sp. nov. is greater than snout length, which distinguishes it from other congeners. The multivariate analysis of morphometric characters using PCA differentiated the new species from D. elopsoides and D. acuta samples collected in this study. The molecular analysis, based on cytochrome c oxidase I, distinguished the new species from D. acuta, D. albulina and D. elopsoides with a high genetic distance of 13.73%, 12.22% and 12.74%, respectively. The maximum-likelihood phylogenetic tree and automatic barcode gap discovery analysis showed the existence of six putative species in Dussumieria. Even the exhaustive sub-clade formation within species and high intra-species genetic distance in D. acuta (1.59) and D. modakandai (1.95) indicate the possibility of a few more cryptic species. This warrants comprehensive sample collection across the distribution range and integrative taxonomic study of the genus Dussumieria.

Genetic and morphological assessment of a vulnerable large catfish, Silonia silondia (Hamilton, 1822), in natural populations from India.

Silonia silondia is a commercially important fish distributed in Asian countries, which is under threat due to overexploitation. This study focuses on the morphological analysis and genetic variation of S. silondia individuals, through truss network and sequencing of two mitochondrial regions, respectively, from six wild populations of the Ganga and Mahanadi river systems in India. A total of 38 haplotypes was observed by analysing combined mitochondrial genes (cytochrome b + ATPase 6/8) in 247 individuals of S. silondia collected from six populations. Average haplotype and nucleotide diversities were 0.8508 and 0.00231, respectively. Genetic structure analysis showed the predominant cause of genetic variation to be within populations. The two clades were observed among the haplotypes and time of divergence from their most probable ancestor was estimated to be around 0.3949 mya. Analysis of combined mitochondrial genes in six populations of S. silondia resulted into three management units or genetic stocks. The truss network analysis was carried out by interconnecting 12 landmarks from digital images of specimens to identify phenotypic stocks. Sixty-five truss morphometric variables were analysed for geometric shape variation which revealed morphological divergence in River Son specimens. The present study presents molecular markers and genetic diversity data which can be critical input for conservation and management of differentiated populations and future monitoring of the genetic bottleneck. The morphological shape analysis clearly shows that variation in the insertion of adipose fin is an important parameter influencing the morphological discrimination.

Studies on bio-chemical profiling of Indian gooseberry (Emblica officinalis) for genetic diversity.

Biochemical profiling of physiologically mature fruits of 51 diverse Indian gooseberry (Emblica officinalis Gaertn) germplasm accessions was collected from Vindhyan hill region of Madhya Pradesh, with a view to select nutraceutically rich genotypes based on important biochemical traits. The mean ascorbic acid and total phenol (tannin) content amongst different accessions was recorded as 496.47 mg 100 g⁻¹ and 4.88% with highest value found in CISH A-12 (654.50 mg 100 g⁻¹) and CISH A-30 (7.18%), respectively. Apart from the above, wide range of variability in the composition of other important biochemical attributes viz., total soluble solids (8.60-17.70°Brix), acidity (1.61-2.94%), total sugar (4.15-9.17), reducing sugar (2.19-4.45%) and TSS/acid ratio (3.89-8.33) was also recorded. Highest significant and positive correlation was observed between total sugar and TSS (0.895) followed by reducing sugar and TSS (0.882). Significant positive correlation between ascorbic acid and tannins (0.551) was an indication to be associated with binding capacity of ascorbic acid over a longer period of storage.

Application of response surface methodology for optimization of polygalacturonase production by Aspergillus niger.

Polygalacturonase (PG) degrades pectin into D-galacturonic acid monomers and is used widely in food industry especially for juice clarification. In the present study,. fermentation conditions for polygalacturonase production by Asgergillus niger NAIMCCF-02958, using mango peel as substrate, were optimized using the 2(3) factorial design with central composite rotatable experimental design (CCRD) of response surface methodology (RSM). The maximum PG activity 723.66 U g(-1) was achieved under pH 4.0, temperature 30 degrees C and 2% inoculum by response surface curve. The experimental value of PG activity wkas higher 607.65 U g(-1) than the predicted value 511.75 U g(-1). Under the proposed optimized conditions, the determination coefficient (R2) was equal to 0.66 indicating that the model could explain 66% of the total variation as well as establish the relationship between the variables and the responses. ANOVA analysis and the three dimensional plots also confirmed interactions among the parameters.