Probiotic effect of Vibrio midae SY9, Cryptococcus sp. SS1 and Debaryomyces hansenii AY1 on the growth and disease resistance of farmed Haliotis midae

Includes bibliographical references.Although the South African abalone, Haliotis midae, has been commercially harvested since 1949, successful cultivation of this species only began in the 1980s. Since then, the abalone mariculture industry has expanded dramatically and currently produces between 500 and 800 tons of abalone per year with a net farm gate value of approximately R125 million. However, disease has had a severe impact on the international aquaculture industry and is anticipated to become an increasingly important factor, together with the slow growth rate of H. midae, that will negatively impact on the further development and success of the local abalone mariculture industry. Thus, the future of H. midae mariculture in South Africa depends in part on the development of methods to enhance the growth rate and disease resistance of farmed H. midae. Erasmus et al. (1997) showed that abalone enteric bacteria enhanced digestive efficiency by secreting polysaccharolytic enzymes and it was suggested from these results that these bacterial enzymes could affect the growth rate of abalone. Furthermore, an overwhelming body of evidence has shown that probiotic microorganisms can significantly improve the growth rate and disease resistance of aquacultured animals. The aim of this study was to isolate enteric microorganisms from H. midae that are capable of hydrolyzing the various protein and starch substrates included in formulated abalone feeds. Upon identification, the selected microbes would be tested for their ability to colonize the digestive tract, improve digestion, growth and immunity of farmed H. midae

Combining computer vision and standardised protocols for improved measurement of live sea urchins for research and industry

To allow sea urchin aquaculture to achieve its intended scale, efficient and precise methods for measuring large numbers of urchins in commercial-scale operations are needed. Current protocols for measuring urchin test (shell) dimensions and mass are time-consuming and prone to high measurement error, thus inconvenient in research and impractical in a commercial context. This study investigates and compares various measurement methods with a newly developed computer vision approach developed in this study, to establish a single protocol using precise, efficient and accessible methodology for measuring live urchins. We show that urchin wet mass can vary up to 8.73% depending on time out of water; this is significantly reduced to an average of 0.1% change by allowing urchins to drip-dry for at least 90 s prior to weighing. We found the conventional vernier calliper method used to measure urchin dimensions to be both time-consuming and imprecise (mean coefficient of variation (CV) of 2.41% for Tripneustes gratilla). Conversely, the computer vision programme we developed measures with higher precision (mean CV of 1.55% for T. gratilla) and is considerably faster. The software uses a series of hue saturation value filters, edge detection algorithms and distortions to measure the diameter of the test (excluding spines) of multiple urchins at once. The software is open-source, and the protocol does not require specialised equipment (can be performed with a mobile phone camera). When the computer vision application is combined with the simple procedures described in this paper, to reduce measurement inaccuracies, urchin wet mass and diameter can be more efficiently and precisely determined. For a larger scale context, this software could easily be incorporated into various tools, such as a grading machine, to completely automate various farm processes. As such, this study has potential to assist urchin data collection in both research and commercial contexts

The effect of fresh seaweed and a formulated diet supplemented with seaweed on the growth and gonad quality of the collector sea urchin, Tripneustes gratilla, under farm conditions

This gonad enhancement study investigates the effect of different fresh and formulated feeds and feeding regimes on the growth and gonad quality of wild-collected adult sea urchin, Tripneustes gratilla, under farm conditions for over 18 weeks. In the first 12 weeks (phase 1), urchins were fed fresh Ulva rigida (U); a 50:50 mixture of fresh U. rigida and Gracilaria gracilis (UG); fresh G. gracilis (G) and a formulated diet 20U (containing 20% U. rigida), and in the final 6 weeks (phase 2) of the study, diet was changed to a formulated feed (20U diet). By the end of phase 1, urchins fed the 20U diet produced gonads (50.72 ± 5.4 g) that were significantly heavier (p < .001) than the gonads of urchins fed the fresh seaweed diets (U, UG & G). By the end of phase 2, gonad weight of urchins in treatment groups UG-20U and G-20U were similar to those fed the 20U-20U diet. Gonad colour of urchins in the G-20U treatment became significantly lighter (ANOVA, p = .029) and poorer quality, compared with urchins in the U-20U group. This gonad enhancement study, conducted on wild collected adult T. gratilla, has shown that a formulated feed (20U diet) can enhance gonad growth and produce commercially acceptable gonads. This farm-based study supports previous findings from aquarium-based studies by our group and indicates that short-term sea urchin gonad enhancement can be carried out under farm conditions in South Africa

Modelling interactions of acid–base balance and respiratory status in the toxicity of metal mixtures in the American oyster Crassostrea virginica

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology 155 (2010): 341-349, doi:10.1016/j.cbpa.2009.11.019.Heavy metals, such as copper, zinc and cadmium, represent some of the most common and serious pollutants in coastal estuaries. In the present study, we used a combination of linear and artificial neural network (ANN) modelling to detect and explore interactions among low-dose mixtures of these heavy metals and their impacts on fundamental physiological processes in tissues of the Eastern oyster, Crassostrea virginica. Animals were exposed to Cd (0.001 – 0.400 μM), Zn (0.001 – 3.059 μM) or Cu (0.002 – 0.787 μM), either alone or in combination for 1 to 27 days. We measured indicators of acid-base balance (hemolymph pH and total CO2), gas exchange (Po2), immunocompetence (total hemocyte counts, numbers of invasive bacteria), antioxidant status (glutathione, GSH), oxidative damage (lipid peroxidation; LPx), and metal accumulation in the gill and the hepatopancreas. Linear analysis showed that oxidative membrane damage from tissue accumulation of environmental metals was correlated with impaired acid-base balance in oysters. ANN analysis revealed interactions of metals with hemolymph acid-base chemistry in predicting oxidative damage that were not evident from linear analyses. These results highlight the usefulness of machine learning approaches, such as ANNs, for improving our ability to recognize and understand the effects of sub-acute exposure to contaminant mixtures.This study was supported by NOAA’s Center of Excellence in Oceans and Human Health at HML and the National Science Foundation

The role of the green seaweed Ulva as a dietary supplement for full life-cycle grow-out of Tripneustes gratilla

This study investigated the use of five different feeding regimes, consisting of different combinations of fresh Ulva armoricana (FU) and dry formulated feeds containing 20% (w/w; 20U) or 0% (0U) dried Ulva, on Tripneustes gratilla somatic growth and gonad production (size, colour and texture) during full life-cycle grow-out in a flow-through tank system. The 32-week trial was divided into two phases, a somatic growth phase (20 weeks) and a gonad enhancement phase (12 weeks), with different combinations of feeds tested during each phase. The five feeding regimes included an FU only treatment for 32 weeks; FU for 20 weeks followed by the 20U diet for 12 weeks (FU-20U); and, similarly, FU-0U, 20U-FU and 0U-FU treatment regimes for 20 weeks and 12 weeks, respectively. Comparable somatic growth was recorded during the first 20 weeks of the trial from juvenile/small adult urchins fed the formulated feed containing Ulva (20U) and the fresh Ulva (FU) diet; whereas a formulated feed with the same nutritional properties, but without the addition of Ulva (0U), produced urchins that were significantly smaller. Gonad production during the first 20 weeks of the trial was higher for urchins fed formulated feeds (0U and 20U); however, the reduced test size of urchins fed the 0U diet resulted in a significantly reduced gonad mass. Following the change in diets at 20 weeks, both gonad size and colour were significantly affected. Formulated feeds promoted gonad growth of urchins previously fed FU, while administration of FU improved gonad colour of urchins previously fed the formulated diets. The FU only treatment produced gonads with the most desirable colour, but these gonads were smaller in size compared with urchins fed dry formulated feeds. These data suggest that the use of high protein formulated diets during the somatic growth phase of small adult urchins is not necessary, as comparable growth can be produced by feeding Ulva. Gonad production on a diet of Ulva alone, however, is significantly lower than that obtained using a formulated diet. It is therefore recommended that FU is used for the somatic growth phases of this species, while formulated feeds, especially the 20U diet, are used subsequently for gonad development and/or enhancement

The role of the green seaweed Ulva as a dietary supplement for full life-cycle grow-out of Tripneustes gratilla

This study investigated the use of five different feeding regimes, consisting of different combinations of fresh Ulva armoricana (FU) and dry formulated feeds containing 20% (w/w; 20U) or 0% (0U) dried Ulva, on Tripneustes gratilla somatic growth and gonad production (size, colour and texture) during full life-cycle grow-out in a flow-through tank system. The 32-week trial was divided into two phases, a somatic growth phase (20 weeks) and a gonad enhancement phase (12 weeks), with different combinations of feeds tested during each phase. The five feeding regimes included an FU only treatment for 32 weeks; FU for 20 weeks followed by the 20U diet for 12 weeks (FU-20U); and, similarly, FU-0U, 20U-FU and 0U-FU treatment regimes for 20 weeks and 12 weeks, respectively. Comparable somatic growth was recorded during the first 20 weeks of the trial from juvenile/small adult urchins fed the formulated feed containing Ulva (20U) and the fresh Ulva (FU) diet; whereas a formulated feed with the same nutritional properties, but without the addition of Ulva (0U), produced urchins that were significantly smaller. Gonad production during the first 20 weeks of the trial was higher for urchins fed formulated feeds (0U and 20U); however, the reduced test size of urchins fed the 0U diet resulted in a significantly reduced gonad mass. Following the change in diets at 20 weeks, both gonad size and colour were significantly affected. Formulated feeds promoted gonad growth of urchins previously fed FU, while administration of FU improved gonad colour of urchins previously fed the formulated diets. The FU only treatment produced gonads with the most desirable colour, but these gonads were smaller in size compared with urchins fed dry formulated feeds. These data suggest that the use of high protein formulated diets during the somatic growth phase of small adult urchins is not necessary, as comparable growth can be produced by feeding Ulva. Gonad production on a diet of Ulva alone, however, is significantly lower than that obtained using a formulated diet. It is therefore recommended that FU is used for the somatic growth phases of this species, while formulated feeds, especially the 20U diet, are used subsequently for gonad development and/or enhancement

The use of stable isotope ratios δ 13 C and δ 15 N to track the incorporation of Ulva and other important dietary ingredients into the gonads of the sea urchin Tripneustes gratilla

In this study, we demonstrate how stable carbon (C) and nitrogen (N) isotope analysis can be used to estimate the allocation of specific dietary ingredients, incorporated into four artificially formulated feeds supplemented with varying amounts of dried seaweed Ulva armoricana (0, 50, 150 and 200 g/kg), to the production of gonads by Tripneustes gratilla over a 20-week growth trial. Results indicate that U. armoricana is an important dietary ingredient for gonad production, accounting for an average of 37.33 ± 1.03% of the isotopic signal recorded for gonads at the end of the growth trial. This is significantly more than fish meal and soya, which only contributed an average of 11.40 ± 1.81 and 3.80 ± 0.09%, respectively, of the isotopic signal of the gonads. Maize and wheat each account for almost 25% of all the dietary ingredients used to formulate the feeds, but their relative contribution to gonad production only averaged 8.55 ± 0.58 and 3.80 ± 0.05%, respectively, among the diets. This indicates that, at least for gonad development, these ingredients may not be required at such high levels. These findings support previous data on the importance of Ulva in abalone and urchin diets, and demonstrate the value of stable isotope analysis for assessing the contribution of specific dietary ingredients in new feed formulations, particularly where growth of specific tissues is being investigated

Effects of chronic hypercapnia and elevated temperature on the immune response of the spiny lobster, Jasus lalandii

The West Coast rock lobster (WCRL), Jasus lalandii, inhabits highly variable environments frequented by upwelling events, episodes of hypercapnia and large temperature variations. Coupled with the predicted threat of ocean acidification and temperature change for the coming centuries, the immune response in this crustacean will most likely be affected. We therefore tested the hypothesis that chronic exposure to hypercapnia and elevated seawater temperature will alter immune function of the WCRL. The chronic effects of four combinations of two stressors (seawater pCO and temperature) on the total number of circulating haemocytes (THC) as well as on the lobsters’ ability to clear (inactivate) an injected dose of Vibrio anguillarum from haemolymph circulation were assessed. Juvenile lobsters were held in normocapnic (pH 8.01) or hypercapnic (pH 7.34) conditions at two temperatures (15.6 and 18.9 °C) for 48 weeks (n = 30 lobster per treatment), after which a subsample of lobsters (n = 8/treatment), all at a similar moult stage, were selected from each treatment for the immune challenge. Baseline levels of haemocytes (THC ml) and bacteria (CFU ml) in their haemolymph were quantified 24 h prior to bacterial challenge. Lobsters were then challenged by injecting 4 × 10 V. anguillarum per g body weight directly into the cardiac region of each lobster and circulating haemocyte and culturable bacteria were measured at 20 min post challenge. No significant differences in THC ml (p normocapnia/high temperature > normocapnia/low temperature > hypercapnia/high temperature. This study demonstrated that despite chronic exposure to combinations of reduced seawater pH and high temperature, the WCRL was still capable of rapidly rendering an injected dose of bacteria non-culturable

The development of a formulated feed containing Ulva (Chlorophyta) to promote rapid growth and enhanced production of high quality roe in the sea urchin Tripneustes gratilla (Linnaeus)

This study investigated growth and gonad production of Tripneustes gratilla fed four protein-rich artificial diets supplemented with varying amounts (0%, 5%, 15% and 20% weight/weight (w/w); designated 0, 5, 15 and 20U, respectively) of the macroalga Ulva over a 12-week period. Gonad size, texture, colour and a number of production performance parameters were quantified and compared with urchins fed fresh Ulva (FU) and a combination of FU and artificial feed (FB). All artificial diets significantly (P _ 0.05) increased gonad somatic indices (GSI) compared with the FU treatment. The 20U treatment increased GSI by 205% by week 9, compared with a 57% increase in the GSI of urchins fed FU. Gonad colour was calculated using three colour parameters, namely L* (lightness), a* (redness) and b* (yellowness). Whereas L* and a* values did not differ significantly between treatments, b* values for all treatments, with the exception of the 20U and FB treatments, were significantly (P _ 0.05) lower or less yellow than the FU treatment by week 12. These results show that we have successfully formulated a feed (20U) which can produce commercially acceptable gonads in terms of both size and colour, indicating the potential for this artificial feed to support commercial echinoculture