Aquaculture Resources Research Articles

Production risk, technical efficiency, and input use nexus: Lessons from Bangladesh aquaculture

AbstractThe optimal use of resources in aquaculture is important, especially in developing countries, to obtain the highest possible outcome from the production process to support food security and poverty alleviation. Thus, within this study, the risk, efficiency, and input‐use variation in aquaculture farms in Bangladesh is investigated using a flexible stochastic frontier model with a risk and an inefficiency function. The results reveal that feed, labor, and capital have positive and significant impacts on production. In addition, an increased fingerling density and a larger farm increase the risk, whereas the use of feed and the capital invested have the opposite effect. Access to extension services has a positive effect and increases farm efficiency. An investigation of the farm size–productivity inverse relationship reveals that this phenomenon is not applicable to Bangladesh aquaculture. In general, efficient farmers are large‐scale farmers, who use a lower stocking density but a higher feeding intensity, resulting in a higher yield. On average, farmers use less labor and feed than what is optimal. To increase efficiency and reduce risk, it is recommended that more technical knowledge on optimal input use, extension service, and capital is made available to aquaculture farmers.

Advances in understanding the impacts of global warming on marine fishes farmed offshore: Sparus aurata as a case study.

Monitoring variations in proteins involved in metabolic processes, oxidative stress responses, cell signalling and protein homeostasis is a powerful tool for developing hypotheses of how environmental variations affect marine organisms' physiology and biology. According to the oxygen- and capacity-limited thermal tolerance hypothesis, thermal acclimation mechanisms such as adjusting the activities of enzymes of intermediary metabolism and of antioxidant defence mechanisms, inducing heat shock proteins (Hsps) or activating mitogen-activated protein kinases may all shift tolerance windows. Few studies have, however, investigated the molecular, biochemical and organismal responses by fishes to seasonal temperature variations in the field to link these to laboratory findings. Investigation of the impacts of global warming on fishes farmed offsore, in the open sea, can provide a stepping stone towards understanding effects on wild populations because they experience similar environmental fluctuations. Over the last 30 years, farming of the gilthead sea bream Sparus aurata (Linnaeus 1758) has become widespread along the Mediterranean coastline, rendering this species a useful case study. Based on available information, the prevailing seasonal temperature variations expose the species to the upper and lower limits of its thermal range. Evidence for this includes oxygen restriction, reduced feeding, reduced responsiveness to environmental stimuli, plus a range of molecular and biochemical indicators that change across the thermal range. Additionally, close relationships between biochemical pathways and seasonal patterns of metabolism indicate a connection between energy demand and metabolic processes on the one hand, and cellular stress responses such as oxidative stress, inflammation and autophagy on the other. Understanding physiological responses to temperature fluctuations in fishes farmed offshore can provide crucial background information for the conservation and successful management of aquaculture resources in the face of global change.

Developing a self-sufficient Philippine milkfish industry through value chain analysis

The Philippine milkfish industry has been dependent on the importation of juveniles for grow-out ever since the decline of wild fry catch and with inadequate supply from local hatcheries. However, self-sufficiency is required to address recent global uncertainties. Value chain analysis of the upstream stages of the milkfish aquaculture pathway reveals options for efficient utilization of coastal aquaculture resources, capital investments and workforce. This paper presents a value chain that starts in an integrated breeding and hatchery (IBH) facility that will produce the required juveniles to yield 7.7 thousand mt milkfish valued at PHP 692 million per year (1 USD = 50 PHP). The number of IBH needed annually were determined, such that the country should have 60 IBH in 2030 to produce 448 thousand mt milkfish worth PHP 61 billion for its 128 million projected population. Economic analysis showed that public-private partnership should fund high-investment but low-profit IBH, while private investors should operate profit-earning hatcheries, nurseries and 4-cage mariculture system to secure the milkfish industry.

Water and Land as Shared Resources for Agriculture and Aquaculture: Insights from Asia

Although agriculture and aquaculture depend on access to increasingly scarce, shared water resources to produce food for human consumption, they are most often considered in isolation. We argue that they should be treated as integrated components of a single complex system that is prone to direct or indirect tradeoffs that should be avoided while also being amenable to synergies that should be sought. Direct tradeoffs such as competition for space or the pollution of shared water resources usually occur when the footprints of agriculture and aquaculture overlap or when the two practices coexist in close proximity to one another. Interactions can be modulated by factors such as hydropower infrastructure and short-term economic incentives, both of which are known to disrupt the balance between aquaculture and agriculture. Indirect tradeoffs, on the other hand, play out across distances, i.e., when agricultural food sources are diverted to feed animals in aquaculture. Synergies are associated with the culture of aquatic organisms in rice paddies and irrigation waters, seasonal rotations of crop cultivation with aquaculture, and various forms of integrated agriculture–aquaculture (IAA), including jitang, a highly developed variant of pond-dike IAA. Policy decisions, socioeconomic considerations, and technology warrant increased scrutiny as determinants of tradeoffs and synergies. Priority issues for the future include guiding the expansion of aquaculture from its traditional base in Asia, taking advantage of the heterogeneity that exists within both agricultural and aquaculture systems, the development of additional metrics of tradeoffs and synergies, and adapting to the effects of climate change.

An exploratory study on establishment of a development direction on education training program for cultivating convergence human resources in smart aquaculture through a demand survey

An exploratory study on establishment of a development direction on education training program for cultivating convergence human resources in smart aquaculture through a demand survey

Environmental refuges increase performance of juvenile mussels Mytilus chilensis: Implications for mussel seedling and farming strategies

Estuarine ecosystems are characterized by a wide physical-chemical variation that in the context of global change scenarios may be exacerbated in the future. The fitness of resident organisms is expected to be influenced by such variation and, hence, its study is a priority. Some of that variation relates to water vertical stratification, which may create “environmental refuges” or distinct layers of water with conditions favoring the fitness of some individuals and species. This study explored the performance of juvenile mussels (M. chilensis) settled in two distinctive water depths (1 m and 4 m) of the Reloncaví fjord (southern Chile) by conducting a reciprocal transplants experiment. Salinity, saturation state and the contents of CO3 in seawater were among the factors that best explained the differences between the two layers. In such environmental conditions, the mussel traits that responded to such variation were growth and calcification rates, with significantly higher values at 4 m deep, whereas the opposite, increased metabolic stress, was higher in mussels raised and transplanted to the surface waters (1 m). Such differences support the notion of an environmental refuge, where species like mussels can find better growth conditions and achieve higher performance levels. These results are relevant considering the importance of M. chilensis as a shellfish resource for aquaculture and a habitat forming species. In addition, these results shed light on the variable responses exhibited by estuarine organisms to small-scale changes in the characteristics of the water column, which in turn will help to better understand the responses of the organisms to the projected scenarios of climate global change.

KELAYAKAN USAHA BUDIDAYA IKAN BANDENG DI SAWAH TAMBAK (Studi Kasus pada Kelompok Tani ‘Makin Makmur” Di Desa Deket Wetan Kecamatan Deket Kabupaten Lamongan)

East Java, which has a large enough potential of fisheries resources for aquaculture, one of which is in Lamongan Regency. Lamongan Regency is a center of aquaculture with a pond rice field area of 23,774.73 Ha which is spread in the middle area and the main product and its mainstay is milkfish. The purpose of this study was to determine the feasibility of milkfish fish farming in ponds in the village of Deket Wetan, Deket District, Lamongan Regency. The method used in this study is a quantitative method, and the sample collection was carried out using a purposive sample in one of the milkfish farmer farmer groups in a rice field named "Makin Makmur". The results showed that the R/C was 1.53, if the R/C> 1, then this business was profitable and feasible to be undertaken, the received BEP was Rp32,722,087, this meant that it had to be able to reach sales of Rp32,722,087 in order to reach the BEP and BEP production volume obtained 1,924 kg, it can be explained that it must be able to produce as much as 1,924 kg of milkfish to reach BEP.

Moving towards more sustainable aquaculture practices: a meta‐analysis on the potential of plant‐enriched diets to improve fish growth, immunity and disease resistance

AbstractAquatic animal diseases are one of the major limiting factors in aquaculture development, with disease emergence forecast to increase with global change. However, in order to treat increasing diseases in a context of global emergence of antimicrobial resistance and strengthening regulations on antimicrobial use, sustainable alternatives are urgently needed. The use of plant supplements to increase fish immunity and disease resistance has gained much popularity within the last decades. The use of functional supplements, such as plants, can also improve growth and feed assimilation, contributing to a better optimization of aquaculture resources (e.g. fish meal inclusion). We conducted a systematic review and meta‐analysis in order to identify the research gaps in the use of plant‐enriched diets in fish aquaculture and estimate, for the first time, the overall efficacy of plant‐enriched diets on fish growth, immunity and disease resistance as well as the effect of intrinsic parameters (fish trophic level, type of plant material, dosage, treatment duration and pathogen species) on the treatment efficacy. We found that plant‐enriched diets significantly enhanced growth, immunity and disease survival of treated fish, regardless of the fish trophic level, treatment duration and type of material used. We also show that plant supplements are a versatile alternative that can benefit different aquaculture sectors (from small‐scale fish farmers to intensive productions). Finally, we observed that studies need to improve the information reported about the plant material used (e.g. origin, identification, chemical composition), in order to allow the comparison of different experiments and improve their repeatability.

Development and current state of seawater shrimp farming, with an emphasis on integrated multi‐trophic pond aquaculture farms, in China – a review

AbstractShrimp farming has been the fastest‐growing sector in seawater aquaculture and has contributed to improving the farmers income and the utilization efficiency of aquaculture resources in China. The shrimp industry has deployed ever‐improved and innovated methods, from extensive farming to semi‐intensive and intensive farming. Various high‐density intensive culture models, such as high‐land, greenhouse and indoor industrialized culture models, have been used for shrimp pond farming in the coastal area. However, efficiency, environmental and social considerations have led to an increasing adoption of the environmentally‐friendly culture model called integrated multi‐trophic aquaculture (IMTA). This has occurred most rapidly along the northern and central coasts of China. The deployed IMTA culture models reviewed here are shrimp + crab, shrimp + fish, shrimp + sea cucumber, shrimp + jellyfish + clam, shrimp + crab + clam, shrimp + crab + clam + fish and the ridgetail white shrimp polyculture in saline alkaline water, which have been tailored to local conditions and organisms' characteristics. Suitable organism varieties and the maintenance of suitable eco‐friendly water quality have been key to success. The eco‐friendly IMTA culture models described here fully exploit the pond culture resources, to increase production with minimal additional feed and labor inputs, while reducing effluent emissions and treatment cost. The performance of shrimp IMTA models is compared to shrimp monoculture models regarding the economics. An equally important outcome of this publication is making generally accessible the findings from a vast Chinese scientific literature on shrimp culture that has hitherto been unavailable in English.

Understanding marine larval dispersal in a broadcast-spawning invertebrate: A dispersal modelling approach for optimising spat collection of the Fijian black-lip pearl oyster Pinctada margaritifera.

Fisheries and aquaculture industries worldwide remain reliant on seed supply from wild populations, with their success and sustainability dependent on consistent larval recruitment. Larval dispersal and recruitment in the marine environment are complex processes, influenced by a multitude of physical and biological factors. Biophysical modelling has increasingly been used to investigate dispersal and recruitment dynamics, for optimising management of fisheries and aquaculture resources. In the Fiji Islands, culture of the black-lip pearl oyster (Pinctada margaritifera) is almost exclusively reliant on wild-caught juvenile oysters (spat), through a national spat collection programme. This study used a simple Lagrangian particle dispersal model to investigate current-driven larval dispersal patterns, identify potential larval settlement areas and compare simulated with physical spat-fall, to inform targeted spat collection efforts. Simulations successfully identified country-wide patterns of potential larval dispersal and settlement from 2012–2015, with east-west variations between bi-annual spawning peaks and circulation associated with El Niño Southern Oscillation. Localised regions of larval aggregation were also identified and compared to physical spat-fall recorded at 28 spat collector deployment locations. Significant and positive correlations at these sites across three separate spawning seasons (r(26) = 0.435; r(26) = 0.438; r(26) = 0.428 respectively, p = 0.02), suggest high utility of the model despite its simplicity, for informing future spat collector deployment. Simulation results will further optimise black-lip pearl oyster spat collection activity in Fiji by informing targeted collector deployments, while the model provides a versatile and highly informative toolset for the fishery management and aquaculture of other marine taxa with similar life histories.

Integrated Use of Multitrophic Aquaculture Resources in the Recreational Business

The article deals with the development of approaches to the integrated use of multitrophic aquaculture resources in the recreational business. It is revealed that multitrophic aquaculture allows successfully combining several areas in nature management. This includes obtaining high-quality food products (both of animal and plant origin), protecting and growing valuable medicinal plants, expanding the area of melliferous plants, and cultivating various industrial crops. It is proved that fish farming, often being extensive, can be considered as a kind of organic farming in the framework of recreational projects using multipurpose reservoirs. It is revealed that reservoirs used in recreational business, as well as the territories directly adjacent to them, are often characterized by an increased level of biodiversity that allows considering such territorial complexes as important stabilizing ecological zones.

Understanding scales of density-dependence to improve the use of resources in benthic mussel aquaculture

Shellfish aquaculture is considered a sustainable way to help meet rising protein demands worldwide. In shallow coastal dynamic ecosystems mussels can be cultivated directly on the seabed, however this method has a low return as mussels exposed to natural environments risk dislodgment, high predation rates, sedimentation and competition. The formation of spatial patterns in natural mussel beds, that result in ‘organized patchiness’, is thought to be an adaptive mechanism to reduce population losses. The driver and effects of this patterning need to be disentangled at multiple spatial scales in which patterns are observed. With a field experiment we aimed to understand how small-scale density (actual cover) and patterning (perimeter: area ratio of clumps and number of mussel layers) can be altered by manipulating large scale density (re-laying biomass), that farmers could control during seeding activity. Within this study we considered the interplay between environmental conditions (manipulating flow rate with the use of large mesh cages) and density for pattern development and persistence, and the repercussions of this on mussel productivity (growth and condition). We further investigated local scale processes, such as the role of within-clump biological activity (biodeposition), that may be a predictor for the larger scale observations of losses and persistence relative to density. We found that manipulating density by controlling seeding biomass from boats is not an accurate predictor of actual seabed density and resulting patterning. The growth and condition of the mussels was only influenced by local scale effects, resulting in high ‘within clumps’ variation. Aiming for an intermediate density to avoid both excessive fragmentation and excessive layering may be viewed as an optimal strategy to maximise returns, but we encourage the incorporation of the hierarchy of multiple scales of density in future studies of patterning that will allow the inclusion of these effects in a model of growth and productivity.

Sex determination in the GIFT strain of tilapia is controlled by a locus in linkage group 23

BackgroundTilapias (Family Cichlidae) are the second most important group of aquaculture species in the world. They have been the subject of much research on sex determination due to problems caused by early maturation in culture and their complex sex-determining systems. Different sex-determining loci (linkage group 1, 20 and 23) have been detected in various tilapia stocks. The ‘genetically improved farmed tilapia’ (GIFT) stock, founded from multiple Nile tilapia (Oreochromis niloticus) populations, with some likely to have been introgressed with O. mossambicus, is a key resource for tilapia aquaculture. The sex-determining mechanism in the GIFT stock was unknown, but potentially complicated due to its multiple origins.ResultsA bulk segregant analysis (BSA) version of double-digest restriction-site associated DNA sequencing (BSA-ddRADseq) was developed and used to detect and position sex-linked single nucleotide polymorphism (SNP) markers in 19 families from the GIFT strain breeding nucleus and two Stirling families as controls (a single XY locus had been previously mapped to LG1 in the latter). About 1500 SNPs per family were detected across the genome. Phenotypic sex in Stirling families showed strong association with LG1, whereas only SNPs located in LG23 showed clear association with sex in the majority of the GIFT families. No other genomic regions linked to sex determination were apparent. This region was validated using a series of LG23-specific DNA markers (five SNPs with highest association to sex from this study, the LG23 sex-associated microsatellite UNH898 and ARO172, and the recently isolated amhy marker for individual fish (n = 284).ConclusionsPerhaps surprisingly given its multiple origins, sex determination in the GIFT strain breeding nucleus was associated only with a locus in LG23. BSA-ddRADseq allowed cost-effective analysis of multiple families, strengthening this conclusion. This technique has potential to be applied to other complex traits. The sex-linked SNP markers identified will be useful for potential marker-assisted selection (MAS) to control sex-ratio in GIFT tilapia to suppress unwanted reproduction during growout.

Genetic diversity of Procambarus clarkii populations based on mitochondrial DNA and microsatellite markers in different areas of Guangxi, China

The red swamp crayfish (Procambarus clarkii) is a famous invasive species. However, it has become one of the most important freshwater aquaculture resources in China. Herein, we focus on five artificial cultured populations of P. clarkii in Guangxi, southern China to investigate the genetic diversity based on mitochondrial DNA and microsatellites. The results revealed that the genetic diversity of P. clarkii populations in southern Guangxi (NN and DT) was lower than in central (LZ and LB) and northern (RS) Guangxi. A total of 17 haplotypes were captured from 100 individuals and haplotype 2 mainly existed, and the number of haplotype in NN and DT was less than other populations. The AMOVA showed that genetic variation was determined by within populations. The observed mismatch distribution of overall populations fit the expected distributions, indicating that no obvious demographic expansion, but unimodal was observed in RS, LZ and LB. Fst among most of groups exhibited moderate differentiation. Nevertheless, the gene flow demonstrated there had extensive gene exchanges between different populations, particularly between LZ and LB. UPGMA tree revealed that NN and DT belonged to the same clade, whereas the remaining populations were in the other clade. According to the genetic diversity, there is a need to improve the germplasm resources of P. clarkii in southern Guangxi.

Apparent digestibility of proximate nutrients, energy and fatty acids in nutritionally-balanced diets with partial or complete replacement of dietary fish oil with microbial oil from a novel Schizochytrium sp. (T18) by juvenile Atlantic salmon (Salmo salar L.)

Oils derived from thraustochytrid microorganisms, particularly Schizochytrium sp., are rapidly gaining attention as sustainable feedstocks to replace conventional edible oils for many industrial applications. A novel strain of Schizochytrium sp. (T18) has shown rapid growth under optimized heterotrophic cultivation, efficiently using inexpensive carbon and nitrogen feedstocks and capable of producing a high docosahexaenoic acid (DHA)-rich oil. This is the first study directed towards its nutritional evaluation as a potential feed resource for salmonid aquaculture. The study examined the effects of partial or complete replacement of dietary marine fish oil with Schizochytrium sp. (T18) microbial oil on apparent digestibility (AD) of dietary proximate nutrients, energy and fatty acids (FAs) when fed to juvenile (32 g) Atlantic salmon (Salmo salar L.). Four isonitrogenous (50% crude protein), isolipidic (20% lipid) and isocaloric (19 MJ/kg digestible energy) practical-ingredient experimental diets were formulated to replace 0, 33, 66 and 100% of dietary fish oil with extracted Schizochytrium sp. (T18) oil. The oil used contained 50% polyunsaturated FAs (PUFA); of which 82% (e.g., 42% of total FAs) was comprised of the dietary n-3 long-chain PUFA (n-3 LC-PUFA) DHA and contained extremely low levels of harmful contaminants (e.g., heavy metals, lipid oxidation products, pathogens). Partial or complete replacement of dietary fish oil with Schizochytrium sp. (T18) oil had no significant (P ≥ .064) effects on AD of dietary dry matter (76–77%), protein (94%), lipid (89–90%) or energy (83–84%). Similarly, AD was unaffected (P ≥ .647) for dietary PUFA (97%) and n-3 PUFA (98%) with only minor differences (P ≤ .046) detected for monounsaturated FAs (MUFA; 91–92%) and n-6 PUFA (95–96%). Alternatively, AD of dietary saturated FAs (SFA) and DHA were significantly (P < .001) improved (70–76% and 95–98%, respectively) with increasing replacement of fish oil with Schizochytrium sp. (T18) oil. Results suggest that conventional fish oil can be completely replaced in juvenile farmed salmon feeds by Schizochytrium sp. (T18) oil with no negative effects on digestibility of dietary proximate nutrients, energy or fatty acids and, in fact, promoting a significant linear dose-response increase in AD of dietary SFA and a statistically significant increase in dietary DHA digestibility.

Research on a novel extraction method using Deep Learning based on GF-2 images for aquaculture areas

ABSTRACT Recently, moderate-resolution remote sensing images have been widely used in extracting coastal aquaculture areas that are usually used to obtain marine fishery resources. However, in moderate-resolution remote sensing images, the aquaculture areas destroyed by storm-tide are hard to be observed. In order to get information of coastal aquaculture areas quickly and accurately, to help the scientific management and the planning of aquaculture resources and to meet the needs of disaster emergency response, it is imperative to extract aquaculture areas based on high-resolution remote sensing images. However, as the spatial resolution increases, there are many disadvantages that traditional pixel-level classification methods bring about, for example, the sediments and some floatage on the water surface are easy to be mistaken as aquaculture areas. In view of these problems, we proposed a novel Semantic Segmentation Network, named Hybrid Dilated Convolution U-Net (HDCUNet), which combines U-Net and Hybrid Dilated Convolution (HDC) to further expend receptive field and prevent the ‘gridding’ problem simultaneously. In this paper, we chose Gaofen-2 images as experimental data to extract aquaculture areas, and the Precisions and Recalls of two types of aquaculture areas are both above 95% and the overall accuracy reaches up to 99.16%. Besides, we compared the extraction accuracy with other four methods: FCN-8s, SegNet, U-Net and Threshold Segmentation (TS) to analyse the extraction effect and verify the validity of HDCUNet.

Phenotypic traits of two boring giant clam (Tridacna crocea) populations and their reciprocal hybrids in the South China Sea

The boring giant clam, Tridacna crocea, is distributed along coasts in the South China Sea, and has formed several geographic populations. These populations represent potentially different genetic resources for aquaculture, and the evaluation of their genetic and production characteristics is important. To determine these performance characteristics, complete diallel crosses between two geographical populations with about 600 km distance, Zhaoshu Island and Huangyan Island, were conducted using pooled gametes at an experimental station in Sanya, Hainan Island Province. Two intra-population crosses (ZZ and HH) and two reciprocal inter-population crosses (ZH and HZ) were carried out successfully three times. High fertilization rates and D larvae rate were observed in all the experimental groups, suggesting that there was no sperm-egg recognition barrier between the two geographic populations. Reciprocal hybrids had a higher survival rate than the pure populations, but with the exception of metamorphosis rate there were no significant differences between the inter- and intra-population crosses. Growth heterosis was evident in both the spat and adult stages, and was mainly influenced by egg origin and mating strategy in the adult stage. In view of the growth differences between the two pure populations' progeny, the Huangyan Island population's progeny was more suitable for giant clam aquaculture than the Zhaoshu Island population's progeny. Our results demonstrate that crossbreeding between the Huangyan Island and Zhaoshu Island populations of boring giant clams can produce considerable heterosis, which has promising prospects for application in the giant clam aquaculture industry in the South China Sea.

Comparison between single and multi-locus approaches for specimen identification in Mytilus mussels

Mytilus mussels have been the object of much research given their sentinel role in coastal ecosystems and significant value as an aquaculture resource appreciated for both, its flavour and nutritional content. Some of the most-studied Mytilus species are M. edulis, M. galloprovincialis, M. chilensis and M. trossulus. As species identification based on morphological characteristics of Mytilus specimens is difficult, molecular markers are often used. Single-locus markers can give conflicting results when used independently; not all markers differentiate among all species, and the markers target genomic regions with different evolutionary histories. We evaluated the concordance between the PCR-RFLP markers most commonly-used for species identification in mussels within the Mytilus genus (Me15-16, ITS, mac-1, 16S rRNA and COI) when used alone (mono-locus approach) or together (multi-locus approach). In this study, multi-locus strategy outperformed the mono-locus methods, clearly identifying all four species and also showed similar specimen identification performance than a 49 SNPs panel. We hope that these findings will contribute to a better understanding of DNA marker-based analysis of Mytilus taxa. These results support the use of a multi-locus approach when studying this important marine resource, including research on food quality and safety, sustainable production and conservation.

Variabilidade Temporal das Concentrações de Clorofila -A e da Temperatura Superficial do Mar na Costa Central de Santa Catarina

O fenômeno das florações de algas é conhecido mundialmente devido aos impactos diretos na saúde dos ecossistemas aquáticos, nos recursos pesqueiros e aquícolas, nas atividades recreacionais e na saúde humana. O presente estudo avaliou o uso de sensores satelitais na quantificação dos parâmetros de temperatura superficial do mar (TSM) e concentração de clorofila-a na superfície do mar (Chl-a) na costa de Santa Catarina, durante o período entre 2002 e 2019, objetivando identificar a variabilidade temporal da TSM e da Chl-a a partir da decomposição das séries temporais em tendência, sazonalidade e resíduos. Para atingir este objetivo foram adquiridas estimativas de TSM e Chl-a oriundas dos sensores orbitais Moderate-Resolution Imaging Spectroradiometer (MODIS) a bordo dos satélites (Aqua e Terra) e Visible Infrared Imaging Radiometer Suite (VIIRS) a bordo dos satélites (SNPP e NOAA-20). Através da extração dos valores de TSM e Chl-a para um ponto ao largo da costa central de Santa Catarina foram geradas séries temporais para o período especificado e aplicada a metodologia de decomposição de séries temporais para identificar oscilações de baixa frequência. Foi possível identificar que os eventos com maior Chl-a estão relacionados com eventos com menores valores de TSM. As componentes encontradas poderão ser utilizadas para modelos preditivos auxiliando assim a minimizar os impactos associados às florações de algas.

Isolation, characterization and growth kinetics of phenol hyper-tolerant bacteria from sewage-fed aquaculture system

Pollution of aquatic resources is increasing day-by-day, and phenolic compounds are common pollutants negatively impacting aquatic biodiversity and production. This study aimed at isolation of phenol hyper-tolerant bacteria from polluted aquaculture resource so that they might be useful in aquaculture systems. Four phenol hyper-tolerant bacterial strains were isolated from sewage fed East Kolkata Wetlands, a Ramsar site. By 16S rDNA sequence, cell morphology and biochemical characteristics the strains PDB2, PDB13, PDB16, and PDB26 were identified as Acinetobacter sp., Acinetobacter junii, Pseudomonas citronellolis, and Bacillus cereus, respectively. Pseudomonas citronellolis strain PDB16, described in this study, is possibly the first report of phenol hyper-tolerant strain in this species. All the four strains degraded 600 mg L−1 phenol within 5 days and expressed catechol 1,2-dioxygenase but lacked catechol 2,3-dioxygenase enzyme suggesting that the bacteria used the ortho-cleavage pathway for phenol degradation. In growth kinetic study Edwards and Aiba model, rather than the most popular Haldane model, gave the best fit indicating behavioral divergence of these strains with those from petroleum contaminated environments. The phenol degrading bacteria isolated from a polluted sewage fed aquaculture system might be useful in degradation and remediation of polluted aquaculture resources as well as inland open waters.