Bottom Cages Research Articles

Assessing the spatial variability of cage movement and velocity attenuation of an off-bottom oyster farm and its influence on eastern oyster (Crassostrea virginica) growth performance

The global shellfish aquaculture industry has expanded over the last seven decades. Similarly, the size of individual shellfish farming operations has grown in some states. Circulation processes in natural water bodies are dynamic and vary across multiple temporal and spatial scales. How gear installation affects the circulation of currents and waves, and subsequent phytoplankton delivery to crops within farms, is largely unknown. Documenting and understanding variability in wave and current energy within an individual farm could help optimize production. Our study sought to understand the variability in oyster growth attributable to hydrodynamic and atmospheric forcing across an active commercial shellfish aquaculture lease in the Patuxent River, Maryland. We observed a 17 % reduction in water flow downstream of the farm (rho = −0.673, p = 0.002, Spearman rank test), suggesting the bottom cages attenuated downstream current velocity during flood tides. Differences in flow speed and the movement of cages and oysters throughout the farm correlated with variances in oyster shell morphology and oyster survival while in bottom cages. Our results demonstrate the occurrence of variability in production within an individual farm location. Further, our findings suggest that insight into the spatial growth patterns across a lease can be practical for forecasting growth and quality of cultured oysters and may enable growers to strategically place oysters within their farm to improve yield and product consistency.

A plant and method of cultivation for sea cucumber <i>Apostichopus japonicus</i> (Selenka, 1867)

A plant and method of the sea cucumber cultivation have been developed and successfully tested. The technology allows to grow sea cucumber Apostichopus japonicus (Selenka, 1867) from juveniles of the current year to adults of commercial size on grounds in unprotected water areas and bottom landscapes unfavorable for habitat of this species. The plant consisted of 5 open-type cages with the size 20x20x1 m mounted on the sea bottom and occupied the area of 400 m2 each (2000 m2 in total). The tests were carried out from the fall of 2018 to late November 2023. After the first two years, only 20.5 % of initial number of resettled factory juveniles had survived, then the number of sea cucumbers stabilized and their distribution density was on average 2.7 ind./m2 (364.4 g/m2) by the end of the experiment. The stock in the cages was replenished annually by larvae from the natural larval pool that was estimated in 6.9 % per year. Monthly weight gains were on average 2.6 g in the last three years of cultivation, though sea cucumbers grew in 3−4 times slower in winter than in summer. The body weight of sea cucumbers by the end of the experiment was 143.9 g/ind., on average. After 5-year exposition, the portion of commercial-sized sea cucumbers (weight ≥ 130 grams) in the cages reached 58.5 % by number and 74.7 % by biomass; their average body weight was 183.6 g. The density of such sea cucumbers distribution in the bottom open-type cages of the plant was 1.5 ind./m2 (272.2 g/m2), on average. Total yield of commercial-sized sea cucumbers harvested from the plant in late November 2023 was 435 kg.

Pathology Anatomy and Hemolymph Profile of Spiny Lobster (Panulirus homarus) Infested by Octolasmis sp. on Bottom Cage

Spiny lobster, a fishery commodity with important economic value, is often infested by Octolasmis sp. on their bodies, which causes stress conditions that lead to death. This study aimed to determine the anatomical pathology and hemolymph profile of spiny lobster infested with Octolasmis sp. in bottom cages. The method used was an observation, where 30 lobsters (weight 112.44 ± 24.63 g) were carried out in June–July 2022 at the Pesona Bahari Wongsorejo, Banyuwangi. Hemolymph profile and anatomical pathology data were analyzed, respectively, using the Independent T-Test and Kruskal-Wallis test (α = 95%). The results based on scoring data showed a very significant difference between infected and healthy lobsters (p < 0.01), characterized by the occurrence of tail flakes, lesions on the carapace, gill melanization, and the appearance of ulcers on the ventral abdomen. A very significant change occurred in the hemolymph profile of infected lobsters compared to healthy lobsters (p < 0.01). Total hemocyte count increased with high concentrations of granular cells, respectively 22.1–37.8 ´x 106 cells/mL and 63.75–64.5%, along with lobster damage, while hyaline cells decreased. This study showed that there was a change in anatomic pathology and hemolymph profile between infected and healthy lobsters.

A novel numerical analysis method for predicting non-Newtonian lubricant (grease) distribution in ball bearings

Grease is a visco-elastic fluid and the most common lubricant for rolling bearings. During the churning phase (initial phase) of bearing operation, most of the grease is collected at various locations in the bearing, e.g. by the seal, at the bottom cage bar, in the cage pockets, which are then called grease reservoirs. These are formed based on bearing operating conditions, grease type, bearing geometry, bearing type. The grease reservoirs supply lubricant to the bearing contacts via bleeding: during operation the oil bleeds out of the reservoirs and lubricates the contacts. Since the distribution of grease is crucial to the bearing lubrication, the design of bearing components e.g., the cage, shall aim at an optimal grease reservoir creation during the churning phase. It is difficult to observe the effect of component design on the grease distribution through real life experiments, so CFD simulations with MPS (Moving Particle Semi-implicit) method are performed here. Flow Simulations with MPS method can help determine the factors influencing the grease distribution inside the bearing after churning, with the final aim of enhancing lubrication. For the current simulations, a CAE software based on MPS, namely Particleworks, was used. Grease consists of a base oil, a thickener, and additives. Since it is a non-Newtonian fluid, it has a nonlinear relation shear stress vs shear rate. It is a visco-elastic material, so it does not flow in the absence of a threshold force. For current simulations, the grease rheology has been modelled using the Herschel-Bulkley model. The model was fitted on in-house rheometer test data and was reduced to a single cage-ball segment. All critical kinematic properties were preserved, that is the speeds of both the inner ring and ball surfaces and the oscillation of the ball position within the pocket as it travels through the loaded and unloaded zones of the bearing. The location and the duration of grease injections resulted in different grease distributions in the model. For demonstration purposes, this document only focuses on the results obtained injecting a grease layer on the inner ring surface in front of the contact. This realistically predicted grease reservoirs to be located at the cage bottom, on the top of cage and in the cage pockets. Sensitivity study on particle size, time step, surface tension and the parametric variation of the bearing speed were also performed. This is an important milestone, as we are able for the first time to virtually simulate the onset of grease reservoirs at locations corresponding to evidence from real bearing operations. The distribution of grease observed at the cage pockets is very important for oil film replenishment. This outcome gives us confidence that the MPS method can be used to support the design of bearing components contributing to enhanced lubrication.

Identification, prevalence and intensity of ectoparasite in sand lobster (Panulirus homarus) cultivated in floating cages (floating net cage) and bottom cage (bottom cage)

Lobster (Panulirus homarus) is one of the marine fishery commodities that is gaining popularity and has been widely cultivated in Indonesia. This is because lobster has great business prospects and is one of the important commodities and has high economic value. Lobster cultivation can now be done in various systems including floating net cages, bottom cages and ponds. The problem that is often faced by cultivators is the emergence of diseases in the lobster cultivation cycle caused by an unbalanced interaction between lobster conditions, the environment, and pathogens. This is one of the main problems in lobster cultivation that can interfere with the survival of lobsters and can also cause death. Research on ectoparasite infection in Sand Lobster (Panulirus homarus) cultured in floating net cages and bottom cages aims to identify the types of ectoparasites and calculate the prevalence and intensity of ectoparasites infecting sand lobster (Panulirus homarus). The method used in this study is a survey method. The sampling method was carried out by random sampling method and the method of analysis and presentation of data using descriptive methods. The main parameters observed in this study were the type of ectoparasites, prevalence and intensity values of sand lobster (Panulirus homarus) infected with ectoparasites, while the supporting parameter was lobster size. The ectoparasite found to infest the sand lobster (Panulirus homarus) was Octolamis angulata. The highest prevalence value was obtained in cultivation using floating net cages of 53,3% which belonged to the Frequently category (commonly) and the highest intensity value was obtained in cultivation using floating net cages of 30,1 which belonged to the Medium category (currently). It is necessary to conduct further studies on Octolasmis species based on the DNA chain arrangement and description of tissue damage due to Octolasmis infestation

Evaluating the influence of cage motion on the growth and shell characteristics of oysters (Crassostrea virginica) among several gear types

An influx of new oyster culture gear provides growers with an expanded ability to grow oysters throughout the water column. Each gear type is exposed to a different regime of physical forces, which is thought to affect oyster production differently; however, there is a poor understanding of the physical conditions inside cages and how they influence the production rate and quality of oysters. A greater understanding of the fundamental relationships between cage motion, oyster growth, and shell shape could help to improve the efficiency of off-bottom oyster production. Such understanding is critical for tailoring gear selection and tuning gear performance to suit grower needs. To address this void, cage motion, internal oyster movement, and oyster growth among three common cultivation methods (Virginia-style bottom cages, Seapa® long-line baskets, and floating cages) were monitored over a single growing season to clarify the role of the physical environment on oyster performance (shell and tissue growth). The averages and variance in motion among each cultivation method were noticeably different, which resulted in significant differences in the growth rate and quality of oysters they produced. Movement of the floating cages and long-line baskets could largely be explained by wind waves generated from a single direction in the field (r2 = 0.49, r2 = 0.36, respectively), while bottom cage movement was far less affected by wind waves. The changes in physical conditions inside each cultivation method demonstrated a trade-off between shell growth rate (a metric of time to market) and shell and meat quality (representative of crop value). These results can help inform growers wishing to strategically adopt cultivation methods that are most aligned with their production goals.

Hydrodynamic analysis of the combined structure of offshore monopile wind turbine foundation and aquaculture cage

Reliable prediction in hydrodynamics is crucial for the design of marine structures, especially for columnar structures such as offshore wind turbine foundations. A combined structure of fixed monopile wind turbine foundation and bottom-seated circular aquaculture cage is proposed for efficiently utilizing the offshore space and reducing the wave forces on the monopile wind turbine foundation. A further developed volume-averaged numerical model is adopted to simulate the pressure drop due to clean and fouled cages by introducing the porous media theory, in which the coefficients of source terms are determined by the least square method based on hydrodynamic force on cage from existing experimental data. The Stokes fifth-order wave theory is considered reliable in simulating the nonlinear waves on slopes and corresponding inline wave force by comparing with multiple existing experimental data. Then the effects of incident wave steepness, seabed bottom slopes and cage diameters on simulation results are analyzed. Results reveal the fouled cage can effectively reduce inline wave forces relative to the clean cage of the combined structure, accompanying a significant resonance effect of wave motion inside the cage.

An assessment of ambient noise and other environmental variables in a nonhuman primate housing facility.

Acoustic noise and other environmental variables represent potential confounds for animal research. Of relevance to auditory research, sustained high levels of ambient noise may modify hearing sensitivity and decrease well-being among laboratory animals. The present study was conducted to assess environmental conditions in an animal facility that houses nonhuman primates used for auditory research at the Vanderbilt University Medical Center. Sound levels, vibration, temperature, humidity and luminance were recorded using an environmental monitoring device placed inside of an empty cage in a macaque housing room. Recordings lasted 1 week each, at three different locations within the room. Vibration, temperature, humidity and luminance all varied within recommended levels for nonhuman primates, with one exception of low luminance levels in the bottom cage location. Sound levels at each cage location were characterized by a low baseline of 58-62 dB sound pressure level, with transient peaks up to 109 dB sound pressure level. Sound levels differed significantly across locations, but only by about 1.5 dB. The transient peaks beyond recommended sound levels reflected a very low noise dose, but exceeded startle-inducing levels, which could elicit stress responses. Based on these findings, ambient noise levels in the housing rooms in this primate facility are within acceptable levels and unlikely to contribute to hearing deficits in the nonhuman primates. Our results establish normative values for environmental conditions in a primate facility, can be used to inform best practices for nonhuman primate research and care, and form a baseline for future studies of aging and chronic noise exposure.

GROWTH MONITORING OF SAND LOBSTER (Panulirus homarus) USING THE BOTTOM CAGE METHOD IN THE EXAMPLE UNIT OF MARINE LOBSTER CULTIVATION, BANYUWANGI REGENCY, EAST JAVA PROVINCE

With the high demand for sea lobster as the industry has developed, Indonesia has an opportunity to establish the world's largest lobster aquaculture production. Therefore, a study related to the growing-out of lobster and also the development of engineering technology of lobster enlargement is needed. This study aims to determine the growth performance of Panulirus homarus reared in a bottom cage method. Lobsters with an average size of 116,25 g were reared for 150 days and fed with trash fish of 3%-4% of the biomass daily. The results showed that the use of the bottom cage method had positive effects on the survival rate, average body weight, specific growth rate dan food conversion ratio was 85%, 170 g, 0.25 g per day and11.16 respectively. The water quality is also was still within the suitable range for lobster rearing.

SEA RANCHING OF Holothuria atra: STOCKING DENSITY AND TIME

Strong market demand and uncontrolled exploitation and/or the inadequate management of fisheries have caused many stocks of sea cucumbers to be overexploited. One suggested effort to overcome this problem is sea ranching. Stocking density is the most important consideration in sea cucumber rearing; therefore, this present work is aimed at elucidating the best stocking density for sea ranching of Holothuria atra. H. atra was taken from the Panjang Island, Jepara waters and reared in bottom cages in Teluk Awur waters, Jepara with a density of 30, 20, or 10 individuals per cage measuring 2 m × 2 m × 1.8 m (with bottom area of 4 m2). Stocking times of H. atra were at the initial time of cage installation, the second and the third months after installation. Bottom sediment characteristics (i.e., chlorophyll a, b, phaeophytin, and total carotene) of the sea cucumber habitat and water quality in the cages were measured monthly during the study. The results showed that growth of H. atra fluctuated; low stocking density yielded a higher weight gain than high stocking density did. The highest weight gain was present in the density of 10 individuals/cage in the second stocking month. The highest survival rate of H. atra was seen in the condition of 30 individuals/cage (93%) at the third stocking month, which means that these sea cucumbers were only reared for three months. The highest mortality occurred at a density of 20 individuals/cage with the survival rate being low (45%) at the first stocking time or in the fifth month of rearing. There was fission evidence among H. atra reared in the cages, resulting in smaller organisms. Among the water quality parameters, the concentration of chlorophyll a, b, phaeophytin, and carotene in the sediment fluctuated according to the time of sea cucumber rearing caused by their feeding and bioturbation. The study results suggested to stock H. atra at low density during the second stocking month to get higher growth.

Comparison of Oyster Aquaculture Methods and Their Potential to Enhance Microbial Nitrogen Removal From Coastal Ecosystems

Coastal ecosystems are impacted by excessive nutrient inputs that cause degradation of water quality and impairments of ecosystem functioning. Regulatory and management efforts to enhance nutrient export from coastal ecosystems include sustainable oyster aquaculture that removes nitrogen in the form of oyster biomass and increases particulate export to underlying sediments where increased organic material may enhance microbial denitrification. To better understand the impacts of oyster aquaculture on nitrogen removal, we examined bacterial processes in sediments underlying three of the most common aquaculture methods that vary in the proximity of oysters to the sediments. Sediment samples underlying sites managed with these different aquaculture methods were examined using the 16S rRNA gene to assess microbial community structure, gene expression analyses to examine nitrogen and sulfur cycling genes, and nitrogen gas flux measurements. All sites were located in the same hydrodynamic setting within Waquoit Bay, MA during 2018 and 2019. Although sediments under the different oyster farming practices showed similar communities, ordination analysis revealed discrete community groups formed along the sampling season. Measured N2 fluxes and expression of key genes involved in denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) increased during mid-summer and into fall in both years primarily under bottom cages. While all three oyster growing methods enhanced nitrogen removal relative to the control site, gene expression data indicate that the nitrogen retaining process of DNRA is particularly enhanced after end of July under bottom cages, and to a lesser extent, under suspended and floating bags. The choice of gear can also potentially increase processes that induce nitrogen retention in the form of ammonia in the underlying sediments over time, thus causing deviations from predicted nitrogen removal. If nitrogen removal is a primary objective, monitoring for these shifts is essential for making decisions about siting and size of aquaculture sites from year to year.

Analysis of reinforced concrete plates with swimmer bars as punching shear reinforcement

Reinforced concrete flat plates are used in buildings and garages. Their design is governed by deflection at the serviceability limit state and punching shear at the ultimate limit state. A new system of punching shear reinforcement consisting of top and bottom steel cages connected through small inclined bars, called swimmer bars, was studied. The objective of the study was to evaluate this system using non-linear finite-element (FE) analysis. FE models were first calibrated based on experimental work carried out previously. A parametric study was then conducted to study the effect of the inclination angle of the swimmer bars, the number of steel pyramids and the number and location of swimmer bars. The results obtained were compared to those predicted by BS EN 1992-1-1:2004 and ACI 318-14. The results of the parametric study indicated that the optimum inclination angle of the swimmer bars was 45°. The first pyramid of swimmer bars assembly had the highest contribution to punching capacity. It was also found that the swimmer bars located at the corners were more effective than the middle bars; accordingly, middle bars could be eliminated and larger corner bars could be used. Finally, the shear legs and swimmer bars were simulated to compare their performance under punching shear.

Growth and survival of Mud Crab, Scylla serrata, reared in bottom and floating cages within Mida Creek mangroves, coastal Kenya

Abstract Mud Crab fattening is a relatively new business idea in Kenya and is highly lucrative due to the reasonable prices offered at tourist hotels. This study was aimed at developing appropriate culture techniques for Mud Crabs to maximize harvestable biomass by the local communities and avoid recruitment overfishing. Growth and survival rates for mixed sex Mud Crabs was investigated for a period of 230 days in Mida Creek, Kenya, using bottom and floating cages, and two feed types in a crab fattening experiment. Crabs attained harvestable weight by the third month for both floating (466.2 ± 137 g) and bottom cages (542.2 ± 109.3 g). There was no significant difference in mean total weight of mixed-sex crabs in the two culture systems (t = 1.75, p>0.05), however males showed significantly higher total weight gain compared to females. A higher overall survival rate was found for crabs cultured in floating cages (63.8%), compared to bottom cages (44.9%). There was no significant difference in growth performance between crabs fed gastropod tissues and those fed fish offal. The long-term specific growth rate for floating cages (0.69 g d-1) was not significantly different from that of bottom cages (0.92 g d-1). An analysis of potential return on investment showed the floating cages to be more profitable per production cycle compared to the bottom ones. The floating cage system and mono-sex male crab culture are recommended to farmers within mangrove tidal flats in Kenya.

The effects of depth and diet on red abalone growth and survival in cage mariculture at San Jeronimo Island, Baja California, Mexico

In recent decades, global abalone aquaculture has significantly increased, while wild abalone fishery landings have decreased drastically, shifting production from fishing to farming. In California (USA) and Baja California (Mexico), overfishing and climate changelinked diseases are thought to be responsible for mass mortalities and significant declines in abalone fisheries landings. Conservation aquaculture is an option for enhancing abalone populations through captive propagation and cage mariculture with subsequent restockings into the wild. To test, inform, and promote innovative sustainable seafood production strategies in the Northeastern Pacific, we designed an experimental mariculture system at San Jeronimo Island, Baja California. We explored the feasibility of rearing juvenile red abalone, Haliotis rufescens, in a near-shore mariculture cage-based production system to supply individuals for local restoration programs. We tested the effects of 2 different depths, surface and bottom (5 m), and 3 macroalgal diets (Macrocystis pyrifera, Eisenia arborea, and a mixed diet of Pelagophycus porra with M. pyrifera) on the survival and growth of juvenile red abalone (32 ± 3.33 mm in shell length) inside cages attached to a long-line system. Over the 90-d experiment, survival was 99% for the surface treatment and 95% for the bottom treatment. Mean daily increment in shell length was 93 ± 12 µm·d–1 in surface cages and 82 ± 13 µm·d–1 in bottom cages. Depth did not affect growth or survival. Growth was highest using the E. arborea diet (99 ± 7 µm·d–1) but not significantly different from the M. pyrifera and mixed diets (88 ± 10 and 74 ± 13 µm·d–1, respectively). High survivorship and growth indicate that San Jeronimo Island can support cage-based mariculture of red abalone and that this strategy may be a useful tool in developing climate-resilient abalone restoration solutions aimed at bolstering seafood production.

Enhanced growth, gonad maturation, and low-level parasite infection in juvenile Manila clam Ruditapes philippinarum cultured in subtidal cages on the south coast of Korea

The growth performance of intertidal marine bivalves is often enhanced when they are transplanted to the subtidal environment due to extended feeding time. In this study, juvenile Manila clams Ruditapes philippinarum were transplanted to subtidal suspended cages (SSC) to examine enhanced growth and reproductive activity. Juvenile clams (11.6 mm in shell length, SL) were placed in cages and suspended at 2 m depth, and shell and somatic growth, gonad maturation, and pathology were monitored. Over 103 days of the experiment, shell and somatic growth of SSC clams were significantly greater than those of the control clams cultured at the intertidal bottom (p < 0 .05). At the end of the experiment, SSC clams reached 29.0 mm in SL, whereas the intertidal bottom cage (IBC) clams only reached 18.0 mm. In late July, after 44 days in the subtidal zone, the first spawning clam was observed, and 80% of SSC clams were actively engaged in spawning by late August. In contrast, spawning in IBC was not observed until late September, and most (25%) remained sexually immature. The protozoan parasite P. olseni was detected after 30 days in the intertidal zone, increasing from 1.6 × 104 cells g−1 tissue wet weight in July to 1.30 × 106 cells g−1 tissue wet weight in September, while P. olseni infection in the SSC clams was not observed until September at much lower intensity (6.6 × 104 cells g−1 tissue wet weight). High mortality of IBC clams occurred in late July, preceded by a dramatic increase in P. olseni infection in August, suggesting that the parasitic infection was, in part, responsible for the mortalities. We speculated that prolonged feeding time in the SSC enhanced growth and gonad maturation and that the high level of parasite infection in the IBC reduced growth and reproduction further.

The effect of aquaculture gear on the growth and shape of the oyster Crassostrea virginica during a “finishing period” in Chesapeake Bay, USA

Growth of the oyster aquaculture industry on the US east coast has accelerated in recent decades due to advances in breeding technologies and grow-out methods. As the industry grows, competition in the market place is likely to increase attention to product quality, for example, shell conformation and meat content. This study investigated how gear type and tidal zone location influenced shell shape and product quality of Crassostrea virginica during a four month “finishing” period at an oyster farm on Fishing Creek MD on the eastern shore of Chesapeake Bay. For these experiments, a mix of sub-market sized, triploid oysters from two local farms were deployed in four gear treatments that varied in water column location and exposure to wave action: OysterGro™ floats, a rack and bag system, a bottom cage placed in the intertidal, and a bottom cage placed subtidally, which represents the ‘control’ treatment (no change of gear type for finishing). Shell height, length, width, and weight (total and wet meat) were measured each month from August to December 2015 and an index of shell shape relative to an idealized 3-2-1 ratio of height to length to width was calculated. Overall, oysters grew well in all gear types (3.0–-4.8 mm increase in shell height per month) and experienced relatively low mortality (4–8% across treatments) – mean height of oysters from each gear treatment exceeded market size by the end of the experiment. Gear treatment had a significant effect on oyster height and weight at the end of the experiment (P < 2.0e–05) and the OysterGro™ treatment produced the largest gains in growth compared to all other treatments (2.3-2.5 fold– increase in wet or total weight). Gear type also affected shell shape (P = 0.023), with significantly lower mean 3-2-1 ratio deviations (more ideal, rounded shells) in the OysterGro™ compared to subtidal bottom cage or rack and bag gear. Shell shape improved the most between initial and final time points for the OysterGro™ treatment, while the rack and bag and bottom cage subtidal treatments showed no improvement. This study provides some of the first data on growth performance and shell shape using the OysterGro™ system in Chesapeake Bay and overall, results indicate that floating gear such as the OysterGro™ system may be a valuable method to finish oysters, facilitating good growth, and improving shape over a relatively short period of time.

The Concentration of Chlorophyll-C in The Bottom Sediment of Sea Cucumber Rearing Cage

The total chlorophyll-c has been proved as indicator of the occurance of diatom and green algal biomass in sediments. Those chlorophyll-c-containing algae acts as food of sea cucumber reared in the cage. The present study was aimed to examine the total chlorophyll-c in the bottom sediment of sea cucumber Holothuriaatra rearing cage with high stocking density (40 ind.4m-2). The sample of sediments were collected from 0-3 cm surface layer of bottom sediment during Mei-July. The chlorophyll-c were analysed using spectrophotometer. spectrophotometrically. The result showed that the chlorophyll-c concentration in the bottom cage sediment fluctuated, decreased due to activity of sea cucumber feeding on microphytobenthos and increased due to their bioturbation activity.

Nursery and Grow‐Out Strategy Optimization in Bay Scallop Argopecten irradians Aquaculture

AbstractThe northeastern United States once had a robust and profitable wild bay scallop Argopecten irradians commercial fishery that generated revenue for fishermen and quality seafood for regional consumption. Since the 1980s, bay scallop landings have been declining due to overfishing, habitat loss, and coastal water quality degradation. There is potential for bay scallop aquaculture to fill the void left by the decline of the wild fishery. However, further investigation into optimizing growth and survival in the nursery, grow‐out, and overwintering phases is needed. Growth and survival as related to stocking density were investigated during the nursery phase using a floating downweller system. Over the 6‐week nursery period, survival, growth, and food availability were documented in relation to flow rates and initial stocking densities. Initial bay scallop stocking density largely predicted mean bay scallop growth rates (mm/d) over the 6‐week observation period but had little impact on survival. At the end of the observation period, bay scallops were moved out of the nursery system to three different grow‐out locations on Cape Cod. At each location, bay scallops were stocked into three surface gear types (floating bags of two different mesh sizes [6 or 9 mm] or hanging trays) and bottom cages to investigate grow‐out phase strategies. In exposed, high‐energy environments, the surface gear was susceptible to damage, and bay scallop growth rates and survival were impacted. In low‐energy environments, growth rates and survival were similar between surface and bottom gear. In both low‐ and high‐energy environments, bay scallop growth rates (mm/d) declined significantly once temperatures dropped below 15°C. Observed growth rates and survival in the configurations examined in this study indicate that bay scallop farming on New England shellfish farms is viable.

Omega‐Hydroxylase Gene Family Contribution to Acetate Levels in Fasting and Starvation

IntroductionSerum acetate levels have been shown to increase with fasting and are implicated in metabolic syndrome as well as tumorigenesis. While the gut microbiota is one source of acetate, studies have shown that short‐chain fatty acid supplementation rescues histone acylation in germ‐free mice. However, the mechanism of conversion of short‐chain fatty acids to serum acetate is unclear. In this study, we demonstrate that serum acetate levels rise with prolonged fasting in correlation with hepatic expression of members of the omega‐hydroxylase gene family.MethodsMale and female C57BL/6 mice, 10–16 weeks of age, previously on a standard chow diet, were removed to wire bottom cages with water ad libitum and fasted for 24, 48, 72 or 96 hours. After a period of fasting, body composition was measured using EchoMRI and mice were sacrificed. Metabolite levels in serum and liver homogenate were quantified using colorimetric assays while mRNA expression levels of a variety of metabolic genes were quantified using absolute qPCR with a dPCR‐confirmed external standard. mRNA expression level findings were confirmed with Western blot. In a supplemental experiment, C57BL/6 mice were injected with CYP4a14 in a viral vector and sacrificed one week later and subjected to similar analysis.ResultsMale and female both showed increased expression of CYP4a with fasting. Hepatic expression of CYP4a10 in males increases from 492 copies/ng cDNA (SD 163) in the fed state to 31,240 copies/ng (SD 3,465) after 24 hours of fasting, while females express 4,680 copies/ng (SD 2,790) at baseline with an increase to 49,072 copies/ng (SD 16,960) after 24 hours of fasting. Similarly, hepatic levels of CYP4a14 in fed females are 20,670 copies/ng (SD 10,280) and increase to 425,950 copies/ng (SD 288,370) at 48 hours of fasting, while males express only 1,300 copies/ng (SD 338) in the fed state but increase to 219,900 copies/ng (SD 213,060) after 48 hours of fasting. In males, serum acetate levels increase from 1.53 mg/dL (SD 2.65) in the fed state to 21.03 mg/dL (SD 10.89) at 24 hours of fasting. In females, serum acetate levels increase from 6.85 mg/dL (SD 2.20) in the fed state to 10.1 mg/dL (SD 2.43) after 24 hours of fasting. CYP4a14 adenovirus infected mice had enlarged livers with increased liver triacylglycerol, free fatty acids, cholesterol and increased serum acetate levels, suggesting that omega‐hydroxylated fatty acids may contribute to production of acetate.DiscussionElucidating the mechanism linking the epigenome to metabolism is critical for the development of strategies for the prevention and treatment of metabolic syndrome and its pathological complications. The CYP4a gene family—already implicated in renal hypertension and colonic tumorigenesis—likely plays a role in the pathogenesis of obesity and perhaps tumorigenesis through increased acetate, which can serve as an alternative energy source and epigenetic modifier of the genome. Further characterization of the omega‐hydroxylation gene family for the purposes of drug development may help ameliorate the metabolic health crises created by high‐fat diets.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Housing influences tissue cytokine levels and the fecal bacterial community structure in rats

Immune measures and the fecal bacterial community were examined in female Biobreeding rats housed in wire bottom cages (wire) or in solid bottom cages containing hardwood chips (bedding). Housing did not affect food intake, weight gain, fecal output or fibre content, serum liver enzymes, or spleen and mesenteric lymph node immune cell populations. Bedding-housed rat feces were enriched in phylotypes aligning within the phylum Firmicutes (families Lactobacillaceae and Erysipelotrichaceae) and had a 2-fold lower content of phylotypes aligning within the phylum Bacteroidetes. Feces from bedding-housed rats also contained significantly more acetic acid and less propionic, isobutyric, valeric and isovaleric acids than those housed on wire. Bedding-housed rats had significantly higher splenic concentrations of interleukin-4 (P < 0.001). These results demonstrate that bedding can indirectly influence systemic and mucosal immune measures, potentially adding additional complexities and confounding results to nutrition studies investigating the health effects of dietary fibres.