The conversion of natural saltmarshes to shrimp aquaculture ponds can potentially influence the biogeochemical cycling of nutrients in coastal wetlands, but its impact on the dynamics of sediment dissimilatory nitrate (NO3−) reduction remains poorly understood. In this study, three sediment NO3− reduction processes including denitrification (DNF), anaerobic ammonium oxidation (ANAMMOX), and dissimilatory NO3− reduction to ammonium (DNRA) were examined simultaneously in a natural saltmarsh and two shrimp culture ponds (5- and 18-year-old) in July and November, using nitrogen (N) isotope-tracing experiments. Our results showed that sediment potential DNF, ANAMMOX and DNRA rates were generally higher in the shrimp culture ponds than the natural saltmarsh in the two seasons. The rates of all three processes generally increased with the age of shrimp ponds, with the magnitude of increase being less pronounced for DNF and ANAMMOX than DNRA. The contribution of DNRA to total NO3− reduction increased significantly following saltmarsh conversion to shrimp ponds, suggesting that DNRA became an increasingly important biogeochemical process under shrimp culture. DNRA competed with DNF and limited reactive N loss to some extent after natural saltmarshes converted to shrimp culture ponds. The results of redundancy analysis revealed that the availability of substrates and sulfides in sediments, rather than the bacteria gene abundance, were the most important factor influencing the NO3− reduction processes. Overall, our findings highlighted that shrimp-aquaculture reclamation may aggravate nitrogen loading in coastal wetlands by promoting the production of bioavailable ammonium.

In order to evaluate the impact of semi-intensive shrimp farming, comparisons between Control and Impact areas were made based on multiple lines of evidence using an asymmetrical design. Water and sediment samples were collected in four shrimp farms located in Todos os Santos Bay, Bahia, Brazil. Nutrients, trace elements and macrobenthic assemblages were evaluated using uni- and multivariate analyzes.Significant differences were observed between Impact and Control areas for the water column dataset (i.e., ancillary variables, SPM, dissolved nutrients and major and trace elements in SPM), whereas no significant differences were observed for the chemistry of sediments. Macrobenthic assemblages were negatively affected by shrimp farm activities. Impacted sites presented the lowest abundance, richness and different structure of macrofaunal benthic assemblages. Farms clearly produced negative impacts in the Todos os Santos Bay. This conclusion was only possible to be reached through the use of multiple lines of evidence. Chemistry and benthic assemblages data combined produced a better description of the quality and impacts of the evaluated environments. Different conclusions would have been reached if chemistry and ecology results were studied separately vs. together.

The aim of this study was to evaluate the influence of a shrimp farm cultivation cycle in the composition of sediments and on the structure of macrobenthic assemblages. Concentrations of nutrients, Zn and Cu were significantly higher in impact than control areas. In general, the level of contaminants was highest during the harvesting period and in sites closest to the discharge of effluents. Abundances and number of taxa of benthic invertebrates were at least one order of magnitude smaller in impacted areas than in controls. The structure of the benthic assemblages was significantly different at these two treatments. The combined use of biological and chemical data showed to be efficient to provide precise answers regarding the extent of impacts caused by shrimp cultivation. The results provide the basis for a better understanding of impacts of this activity and can subsidize the development of better management practices for coastal areas.

The world production of farmed Whiteleg shrimp was 5,812,180 t in 2020. Ecuador, Mexico, and Brazil produced 1,012,830 in that year according to data FishStatJ. Environmental impact studies were scarce given the rapid growth of this activity, mainly on cummulative impacts, loss of ecosystems services or resilience of wetlands and mangroves. Aspects of the management of environmental impacts published on American studies during 1986–2020 are analyzed. The main impacts included the loss of mangroves and their transformation of these ecosystems and their water bodies by receiving enriched effluents from shrimp farms. Different management measures are discussed between Ecuador, which contributes 63.76 % of American production of white leg shrimp; Brazil which published 46.2 % of the environmental studies of the analyzed period, and Mexico, in an intermediate situation. Finally, alternatives are discussed to improve the management of shrimp aquaculture with emphasis on the Ecuadorian context.

Shrimp aquaculture is one of the fastest growing food-producing avenues, where antibiotics usage has become an issue of great concern due to the development of antimicrobial resistance in bacteria. A total of 2304 bacterial isolates from 192 samples (sediment, water, shrimp, and source water) from Andhra Pradesh, India were screened. Antibiotic resistance of bacterial isolates was highest for oxytetracycline (23.4%) followed by erythromycin (12.7%), co-trimoxazole (10%) ciprofloxacin (9.6%), and chloramphenicol (6%), of which 11.9% isolates were multi-drug resistant. Bacterial isolates from shrimp (26.7%), water (23.9%), and sediment (19.6%) samples exhibited more resistance (p ≤ 0.05) towards oxytetracycline. Higher antibacterial resistance was observed from samples of southern Andhra Pradesh (locations L6 and L7). Gram negative bacteria were more prevalent (64%) and showed significantly (p ≤ 0.01) higher resistance. This study indicated the wider distribution of antibiotic-resistant bacteria in shrimp aquaculture ponds with potential risk to humans and the environment.

Using structured surveys in 2008 and 2016, change in disease burden and use of chemical treatments in Bangladesh shrimp farm management was examined. Overall, disease burden had increased in all farms and was more polarized, with a fewer number of individual infectious diseases responsible for most disease in ponds. Farmers also reported physical deformities, nutritional deficiencies, and unknown diseases further indicating poor health of their stock. To combat the threat, more chemical treatments were used (5.2 treatments per farm in 2008 versus 28.8 in 2016), resulting in an average increase of 424% in the number of active substances entering shrimp ponds. Although there was a modest reduction in the use of antimicrobials, shrimp was being exposed to a wider range of chemicals during rearing. The subsequent concern for the environment, animal and human health demands further research to identify potential risks from residues of chemical products.

In characterization of food borne pathogens from the environment, assessment of virulence, genetic diversity and AMR are essential preludes to formulate preventive strategies and to combat the spread. This study aimed to identify and characterize pathogenic Vibrio parahaemolyticus in the coastal aquaculture farms of Kerala, India. Twenty-seven β-haemolytic V. parahaemolyticus were isolated from 7 out of 40 farms studied. Among the 27 isolates, 15 possessed the tdh gene and 4 had trh. ERIC PCR and PFGE illustrated the presence of pathogenic isolates that shared genetic similarity with clinical strains. One pathogenic isolate was identified to be multidrug resistant (MDR) and 59% exhibited a MAR index of 0.2 or above. Seventy four percent of the pathogenic isolates were ESBL producers and 3.7% of them were carbapenemase producers phenotypically. This asks for adoption of control measures during farming to prevent the transmission of pathogenic V. parahaemolyticus to the environment and food chain.

The widespread use of antibiotics in aquaculture can potentially lead to the emergence of antibiotic resistance genes (ARGs) and threaten human health by entering the food chain. To assess the environmental risk posed by antibiotics in China, the spatial-temporal distribution and correlation of 8 antibiotics based on the abundance of 11 ARGs in water sources, pond water, and sediment in 8 ponds were determined. The results indicated that sul1 was the predominant ARG in water sources and pond water, and tetC was the most in the sediment. A trend of increasing abundance of ARGs was observed with increased rearing density and pond age. Compared to monoculture, shrimp culture integrated with different trophic levels of fish farming could influence the abundance of ARGs. There was also a significant correlation between the abundance of ARGs and antibiotic concentration in the sediment, while no correlation was observed in water sources and pond water.

Discharge of effluents loaded with phosphorus (P) from anthropogenic activities constitutes serious eutrophication risks in marine and terrestrial ecosystems, including mangroves. Three mangroves in NE-Brazil were studied to evaluate the impact of P-rich-effluents from shrimp farming and domestic sewage, in relation to a control area (natural mangrove). Soil phosphorus fractionation and water chemical analysis were performed to assess potential pollution. We observed the most labile P forms increased gradually and significantly from control to sewage to shrimp farm impacted mangroves as observed by increasingly dissolved orthophosphate (PO₄³⁻) content in water and the exchangeable/soluble P (Exch-P) extracted from soils, which is supported by the discriminant analysis. Exch-P results were correlated to Humic-Acid-P, which can release more labile P forms when mineralized. Our results demonstrate a substantial impact of aquiculture and sewage effluents in mangroves at both organic and inorganic P fractions, raising important concerns regarding pollution for these marine ecosystems.

Environmental antimicrobial resistance (AMR) has drawn increasing attention due to its great risk to human health. The aim of this study was to investigate AMR and genotyping of Vibrio parahaemolyticus isolates (n = 114) recovered from shrimp mariculture environment in China. The isolates exhibited a high rate of resistance to streptomycin (78.9%), ampicillin (64.9%) and gentamicin (53.5%). Furthermore, multi-drug resistance was highly prevalent (61.4%), in which 95.9% of these ampicillin-resistant isolates were primarily mediated by blaCARB-17. Surprisingly, doxycylcine, florfenicol, and trimethoprim/sulfamethoxazole (TMP/SMZ) resistance genes occurred in susceptible isolates. Moreover, 114 isolates were grouped into unique pulsed field gel electrophoresis patterns. These findings suggest the need for the prudent use of antimicrobial agents on mariculture farms, in order to control the dissemination of antimicrobial resistant V. parahaemolyticus.