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Made available in DSpace on 2022-04-28T19:42:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The objective of this study was to evaluate tilapia, Oreochromis niloticus, for the biological control of suspended solids in an integrated biofloc technology (BFT) system rearing red drum, Sciaenops ocellatus, and Pacific white shrimp, Litopenaeus vannamei. Four integrated systems were structured with recirculating water in closed circuits composed of separate tanks for each species. The experiment compared the use of tilapia to control suspended solids (biological treatment [BT]) to control systems without tilapia. The initial mean weights and stocking densities were: 2 g and 250 ind/m3 for shrimp; 71 g and 1.04 kg/m3 for red drum; and 85 g and 5.12 kg/m3 for tilapia. Temperature, dissolved oxygen (DO), pH, alkalinity, salinity, total suspended solids, total ammonia nitrogen (TA-N), and nitrite were measured. Temperature, DO, pH, alkalinity, and TA-N were maintained within guidelines recommended for shrimp, red drum, and tilapia. Nitrite concentrations remained within guidelines for red drum and tilapia. No significant difference in growth performance between the control and BT was observed, but the apparent consumption of solids in systems with tilapia resulted in decreased particulate matter in the effluent compared to the control. The study showed that the tilapia could control the suspended solids when integrated with red drum and marine shrimp culture with BFT in an integrated multitrophic system. Federal University of Rio Grande – FURG Institute of Oceanography Marine Aquaculture Station Waddell Mariculture Center – South Carolina Department of Natural Resources (USA) Universidade Estadual Paulista – UNESP Universidade Estadual Paulista – UNESP

Biofloc-based systems use little water and may recycle nutrients through the water column microbial community; fish-free diets may be more ecologically and financially sustainable than traditional feeds. A 12-week study examined the effects of biofloc (solids) management and a fish-free diet on shrimp quality. Four treatments were created; two used a conventional feed (including fishmeal and fish oil), one with solids management (CF-S) and one without (CF), and two treatments used a fish-free feed, one with solids management (FF-S) and one without (FF); each treatment was randomly assigned to four 3600-L tanks. The FF and FF-S shrimp had significantly lower lipid concentration and more manganese. Potassium was higher in CF-S shrimp versus CF; phosphorus was lowest in FF-S shrimp, and FF shrimp had the highest zinc levels. The CF shrimp had significantly higher omega-3s than FF shrimp, although omega-3 levels in FF shrimp were higher than the feed. This, coupled with higher omega-3 levels in the biofloc than the feed, may indicate that shrimp obtained some fatty acids from the biofloc material. The CF-S and FF-S shrimp had significantly greater sweet aromatic aroma, and the FF and FF-S shrimp had significantly higher first bite moisture release, mastication moisture release, and mastication fibrous/stringy texture. These results should be considered to optimize product quality of biofloc-raised shrimp fed fish-free diets.

White shrimp (Litopenaeus setiferus) fisheries-independent and fisheries-dependent landings can be highly variable and may be related to environmental factors that influence growth, mortality, and survival. We used linear regression analysis to look for potential relationships between environmental and white shrimp catch-per-unit-effort (CPUE) data collected from the Ashepoo-Combahee-Edisto (ACE) Basin National Estuarine Research Reserve (NERR) for four critical months in the shrimp life cycle. This analysis used data from white shrimp fisheries-independent CPUE (2002 to 2014) and water quality and meteorological variables for August (juvenile), December (sub-adult), March (adult), and April (spawning adult). The results showed that shrimp CPUE was mainly correlated with water temperature, salinity, and dissolved oxygen concentration collected through the ACE Basin NERR’s System-Wide Monitoring Program (SWMP), but offshore wind, precipitation, and intra-annual CPUEs also partially explained the variability in monthly CPUEs. Black gill prevalence was correlated with water temperature and salinity. Additionally, our analysis found that winter water temperatures of ≤11 °C were correlated with reduced shrimp abundance the following spring. Ultimately, managers would like to successfully predict white shrimp stock abundance throughout fishing seasons based on environmental conditions. This study is a first step in identifying the environmental variables that may be useful in predicting white shrimp CPUE in the South Atlantic Bight. The techniques employed here can serve as a basis for predicting and managing other wild annual fisheries stocks.

The microbial community in minimal-exchange, superintensive culture systems should be managed to cycle nutrients and enhance production. This paper explores the effects of biofloc concentration reduction and a fish-free diet on several microbial community characteristics. In 16, 3.5-m diameter, 71-cm deep outdoor tanks, shrimp were stocked at 460/m3. Eight of the tanks received a fish-free, plant-based feed and eight received a conventional feed containing fishmeal and fish oil. Within each diet type, biofloc concentration was reduced in four of the tanks and was not reduced in the other four tanks. Photosynthetically active radiation (PAR) extinction coefficients, photosynthetic oxygen production, chlorophyll-a (chl-a) concentrations, pheophytin-a (pheo-a) concentrations, and the sum of odd and branched chain fatty acid concentrations as a bacterial abundance indicator (BAI) were measured. Biofloc reduction significantly (P≤ 0.003) decreased PAR extinction coefficients, chl-a concentration, pheo-a concentration, and BAI concentration, while significantly increasing photosynthetic oxygen production. Diet did not significantly affect (P > 0.05) any of these measured parameters. The observed changes in microbial community characteristics corresponded with, and may help to explain, significantly improved shrimp feed conversion ratios, growth rate, final weight, and biomass yield in the tanks with biofloc reduction.

Microalgae hold a key role in the diet of the world's highest-valued seafood species, Pacific white shrimp Litopenaeus vannamei, but ingestion, digestion, and feeding mechanisms employed for consuming suspended microbes are not well studied. The goal of this work was to determine whether juvenile L. vannamei could consume and digest several microbes of varying sizes and structures in suspended monocultures. Diatoms Thalassiosira weissflogii and Amphiprora sp., eustigmatophyte Nannochloropsis salina, and cyanobacterium Synechococcus bacillarus were chosen based upon their common occurrence in intensive shrimp aquaculture systems. Juvenile 2 g L. vannamei, previously starved for 24 h, were individually stocked in aerated flasks containing axenic monocultures of T. weissflogii, Amphiprora sp., N. salina or S. bacillarus for 15, 30, 60, and 90 min. After designated immersion times, shrimp were dissected for collection of stomach and intestine content samples. Fluorometry was used to measure chlorophyll a (μg/g) within the stomach and intestine contents at each time increment. Counts of intact cells (cells/g) within the stomach and intestine contents were completed for shrimp that had been immersed for 60 min. Shrimp demonstrated a sweeping behavior of the third maxillipeds during submersion in some algal cultures, which led to examination through scanning electron microscope photography. Counts of intact cells and chlorophyll a levels in the stomach and intestine indicated that juvenile shrimp actively ingested and digested T. weissflogii and Amphiprora sp. from suspended monocultures. Diatom consumption and digestion were evident across all immersion times, with increasing levels of chlorophyll a in stomach samples up to but not significantly beyond 60 min, indicating that the experimental time period represented a continuous feeding period and spanned the gut passage time. Shrimp were able to ingest S. bacillarus and N. salina to a very limited degree, but there was no evidence of digestion of these cells. Examination under the scanning electron microscope revealed that the third maxillipeds have net-like setae which could potentially select for microorganism > 10 μm in size. Since this cell size reflected the difference between those cells consumed or not consumed in this study, we hypothesize that these appendages may be used by juvenile L. vannamei to filter food particles. These observations provide valuable insight regarding this shrimp's ability to capture and digest microalgae both within its natural environment and in aquaculture systems.

Minimal-exchange, intensive culture systems require little, if any, water exchange and have high animal stocking densities. Intensive nutrient inputs lead to an abundant community of microorganisms. These microbes are partially contained within suspended “biofloc” particles and contribute to water quality maintenance and provision of supplemental nutrition to the culture species. Optimal function of minimal-exchange, intensive systems is likely dependent on the structure of the microbial communities within them. This document offers a short review of microbial groups important for intensive marine aquaculture and descriptions of three methods for quantifying their abundance. The document also describes an experiment during which these methods were used to monitor the effects of partial biofloc removal on microbe abundance. The first method uses light microscopy, with the option of epifluorescence, along with a ranking system to enumerate the abundance of microbial taxa. The second method exclusively uses epifluorescence to illuminate chlorophyll and cyanobacteria pigments. Images are taken of each fluorescing group of pigments and processed using image analysis software to quantify the respective abundance of the two pigment types. Using the third method, changes in bacterial abundance were determined by gas chromatographic measurement of bacteria-specific fatty acids in solvent extracted water column lipids. Using these techniques, it was determined that removing solids from the culture water significantly (P ≤ 0.01) reduced the abundance of nematodes, rotifers, cyanobacteria, and bacteria. Understanding microbial composition and the effects that management protocols have on that composition may help system managers make better informed decisions.

In minimal-exchange, superintensive culture systems, the flocculated (biofloc) particles that accumulate may provide benefits for cultured shrimp; however, excessive particle accumulation can hinder shrimp performance. Also, the shrimp aquaculture industry is reliant on marine fish-based feeds. Using these products can lead to exploitation of marine resources, the introduction of contaminants to cultured shrimp, and unstable production costs. This study examined the use of simple, side-stream settling chambers as a means of controlling the abundance of particles in the water column and demonstrated the effects on water quality and shrimp production. The study also compared water quality and shrimp production parameters between a commercial, fish-based diet and a diet formulated almost entirely from vegetarian components, with expelled soybean meal as its principle protein source. The fish-based diet and the plant-based diet each contained 35.7% and 36.4% crude protein and 11.0% and 10.8% total lipid, respectively. The experiment was conducted in 3.35 m diameter, outdoor tanks, shrimp were stocked at 460 m − 3 and grown for 12 weeks. By the end of the experiment, settling chambers had removed 59% of suspended solids, decreased turbidity by 57%, reduced nitrate–nitrogen concentration by 60%, reduced phosphate concentration by 61%, and caused a 33% increase in alkalinity, all highly significant effects. Settling chambers also contributed to significantly improved shrimp feed conversion ratio, biomass, growth rate, and final weight ( P = 0.002, 0.006, − 3 ) was 41% greater in treatments with solids management than those without. Shrimp survival was not statistically different with or without settling chambers. Water quality parameters were not statistically different between the two diet types, except phosphate concentration which, by the end of the experiment, was 34% lower in the tanks receiving the plant-based diet. Shrimp production parameters were not statistically different between the two diets. The study showed that controlling the concentration of particles in superintensive shrimp culture systems can significantly improve water quality and shrimp production. Also, an environmentally friendly and potentially economical plant-based diet can produce results comparable to a fish-based feed in superintensive shrimp culture systems.

Gross and net photosynthesis, and water column respiration of a super-intensive Litopenaeus vannamei raceway culture with zero water exchange were measured over 21 weeks using the light and dark bottle method. Spearman correlation analysis was used to explore the relationship of these parameters with other water quality parameters (O2, temperature, pH, alkalinity, TAN, NO2, NO3, dissolved orthophosphate, turbidity, TSS and VSS) and of shrimp performance based on growth rate and feed conversion rate. Net photosynthesis generally had negative values, indicating that the system was predominantly heterotrophic. Gross photosynthesis was significantly related only with VSS, and water column respiration was related only with turbidity. Shrimp growth rate increased with higher temperature and dropped with higher pH. Nitrite had a strong inverse relationship with shrimp growth rate (R2 = 0.8044, p

Reduction or elimination of fish meal and fish oil from aquaculture diets can help to reduce the potential for contamination and dependence of the industry on pelagic fisheries while improving economic competitiveness. However, fish oil provides important omega-3 (n-3) fatty acids (FAs) essential to shrimp health and beneficial to humans. This study evaluated an organic, plant-based diet formulated to replace fish meal and fish oil with plant proteins and docosahexaenoic acid (DHA) produced by algal fermentation. Shrimp cultured in replicate outdoor ponds at 25/m2 were fed either a diet composed of organically produced plant ingredients or a conventional commercial fish-meal-based feed. No significant differences were found in production parameters between the conventional fish-meal-based diet and the plant-based diet (production: 4594 and 4592 kg/ha; harvest size: 18.7 and 19.2 g; survival: 93 and 88%; and feed conversion ratio: 1.4 and 1.3, respectively). At harvest, shrimp were analyzed for 147 chemical contaminants and 71 FAs. Contaminant levels were negligible for shrimp raised on both diets. The fish meal and fish oil diet provided significantly higher quantities of eicosapentaenoic acid and DHA than the plant-based diet, and the shrimp fed the conventional diet reflected this with higher levels of these beneficial FAs in edible tissues. Differences between feeds and shrimp tissues suggest that essential n-3 FAs may accumulate in shrimp tissues over time or that natural pond productivity may play a role in providing supplemental nutrition. Shrimp raised on the two diets and wild-caught shrimp are clearly distinguishable by their FA profiles. Compared to alternative protein sources like beef, pork, or chicken, differences in lipid profiles of shrimp raised on either diet may be insignificant because both offer increased human health benefits.