Shrimp aquaculture in India is synonymous with coastal aquaculture. Like other agricultural activities, it appropriates a wide range of environmental goods and services, and is vulnerable to impacts of climate change as the cultured animals are sensitive to various kinds of biotic and abiotic stressors. Climate change affects the shrimp aquaculture directly by extreme weather events and seasonal variations, and indirectly alter the primary and secondary productivity, structure and composition of the ecosystems or by influencing the availability of fishmeal, fish oil and other goods and services required for aquaculture farmers. The perceptions of farmers on the impacts of climate change on shrimp aquaculture in inland and coastal areas of Krishna District, Andhra Pradesh are discussed. Cyclone and flood were perceived by all the farmers, whereas irregular season, high temperature, heavy rain and drought were perceived by 79, 89, 91 and 5 % of farmers, respectively. Environmental, biological, and economic impacts of climate change drivers on aquaculture indicated 20 to 30 % loss due to seasonal variations and 50 to 100% loss due to extremely heavy rainfall, flood and cyclones. The economic risk rating was high with flood followed by the cyclone and the magnitude was more in coastal areas compared to inland areas. There is no universally applicable list of adaptation measures and need to be evaluated for individual aquaculture systems. Autonomous and planned adaptation measures to be implemented by farmers, researchers and policymakers are discussed for climate-resilient aquaculture. Planned adaptive measures are either at the primary level or non-existence, hence policy initiatives are required to formulate planned adaptive measures to enhance the adaptive capacity of the farmers.
Vibriosis is regarded as an important disease of penaeid shrimps affecting larvae in hatcheries. Among the Vibrio species, Vibrio parahaemolyticus, Vibrio vulnificus, Vibrio furnissii, Vibrio campbellii, Vibrio harveyi, Vibrio alginolyticus, and Vibrio anguillarum are often associated with diseases in finfish and shellfish of brackishwater ecosystem. Accurate species differentiating methods for the organisms present in an ecosystem are required for precise classification of the species and to take steps for their management. Conventional methods like 16s rRNA phylogeny and multilocus sequence typing (MLST) have often failed to correctly identify Vibrio species. This has necessitated a comprehensive investigation on methodologies available to distinguish Vibrio species associated with brackishwater aquaculture system. To achieve this, 35 whole genomes belonging to 7 Vibrio species were subjected to phylogenetic analysis based on 16s rRNA gene, MLST genes, single-copy orthologous genes, and single-nucleotide polymorphisms. In addition, genome-based similarity indices like average nucleotide identity (ANI) and in silico DNA-DNA hybridization (DDH) were computed as confirmatory tests to verify the phylogenetic relations. There were some misclassifications occurred regarding phylogenetic relations based on 16s rRNA genes and MLST genes, while phylogeny with single-copy orthologous genes produced accurate species-level clustering. Study reveals that the species identification based on whole genome-based estimates or genome-wide variants are more precise than the ones done with single or subset of genes.
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