GROWTH CHARACTERISTICS OF NEWLY ISOLATED INDONESIAN MICROALGAE UNDER DIFFERENT SALINITY

The aim of this study was to investigate the growth characteristics of microalgae strains isolated from Kendari Bay and the Wanggu River estuary, Indonesia. The growth of the isolates, denoted as Kb1-2, Kb1-3, Kb1-5, and Kb2-6, were evaluated under controlled conditions. A batch culture experiment of these strains except Kb2-6 was conducted for 15 days under salinity levels of 20, 25, 30 and 35 gL-1. Tetraselmis chui, Tisochrysis lutea and Chaetocero sneogracile were also culture and used as the growth references. Cell density was measured every day and cell size was measured from 50 live cells during the logarithmic phase. The cell sizes of three of the four Indonesian microalgae ranged from 1.2-11.8 µm, considered suitable for shrimp larvae. The Indonesian strains started the logarithmic phase of growth at all salinities tested from day 0 to day 3 after inoculation except for Kb1-3 that started the phase after a 3-day lag. Increased cell density over the culture period and division rate of Indonesian microalgae during the logarithmic phase of growth were similar at all salinities tested and similar to T. chui, Ti. lutea and C. neogracile. However, the final biomasses after 15 days of culture of all microalgal strains were affected by culture salinities tested. Indonesian microalgal strains showed similar dry weight and ash free dry weight to smaller-cell strains, Ti. lutea and C. neogracile. Indonesian strains (other than Kb2-6) are suggested as suitable live food candidates for mass culture in shrimp hatcheries based on their cell size, ability to survive long culture periods, and wide salinity tolerance

Combined effects of a parasite, QPX, and the harmful-alga, Prorocentrum minimum on northern quahogs, Mercenaria mercenaria

Northern quahogs, Mercenaria mercenaria (L.), frequently are infected with the parasite Quahog Parasite Unknown (QPX, Labyrintohomorpha, Thraustochytriales), which can cause morbidity and mortality of the quahogs. Possible interactions between this parasitic disease and exposure to the harmful dinoflagellate Prorocentrum minimum in M. mercenaria were studied experimentally. Quahogs from Massachusetts with variable intensity of QPX infection were exposed, under controlled laboratory conditions, to cultured P. minimum added to the natural plankton at a cell density equivalent to a natural bloom. After 5 days of exposure, individual clams were diagnosed histologically to assess prevalence and intensity of parasitic infection, as well as other pathological conditions. Further, cellular defense status of clams was evaluated by analyzing hemocyte parameters (morphological and functional) using flow-cytometry. Exposure of quahogs to P. minimum resulted in: a lower percentage of phagocytic hemocytes, higher production of reactive oxygen species (ROS), larger hemocyte size, more-numerous hemocytic aggregates, and increased numbers of hemocytes in gills accompanied by vacuolation and hyperplasia of the water-tubular epithelial cells of the gills. Quahogs had a low prevalence of QPX; by chance, the parasite was present only in quahogs exposed to P. minimum. Thus, the effect of QPX alone on the hemocyte parameters of quahogs could not be assessed in this experiment, but it was possible to assess different responses of infected versus non-infected quahogs to P. minimum. QPX-infected quahogs exposed to P. minimum had repressed percentage of phagocytic hemocytes, consistent with immuno-modulating effect of P. minimum upon several molluscan species, as well as smaller hemocytes and increased hemocyte infiltration throughout the soft tissues. This experiment demonstrates the importance of considering interactive effects of different factors on the immunology and histopathology of bivalve shellfish, and highlights the importance of considering the presence of parasites when bivalves are subjected to harmful-algal blooms

Salinity Effects on Growth and Nutritional Content of Newly Isolated Microalgal with Potential Use in The Shrimp-Hatcheries

A two-week batch experiment was conducted on three newly isolated Indonesian microalgal strains (Kb1-2 identified as Chaetoceros sp., Kb1-3 and Kb1-5) and Tisochrysis lutea to determine salinity effects upon the growth, proximate composition and ω-3, eicosapentaenoic acidand docosahexaenoic acid, (EPA and DHA) and ω-6 (arachidonic acid /ARA) fatty acids. Salinity within each strain growth of all microalgae tested. The highest cell densities were observed in Indonesian strains, Kb1-3 on day 8 at 25 psu and Kb1-5 on day 10 at 35 psu. Salinity significantly affected the lipid, protein and carbohydrate content in all microalgae cultured. The highest total lipid content was found in T. lutea cultured at 30 psu (28.3 %) followed by Kb1-2 cultured at 20 psu (25.0 %) and T. lutea at 35 psu (24.8 %). Kb1-3 produced highest protein when cultured at 20 and 25 psu, decreasing at higher salinities of 30 and 35 psu, 44.7 and 39.2 % to 31.5 and 32.6 %, respectively, similar to T. lutea. Kb1-5 had higher protein at both 25 and 35 psu but showed lower protein levels at 20 and 30 psu. Indonesian strains showed almost a similar content of carbohydrate across culture salinities similar to T. lutea. Although all Indonesian microalgae contained important ω-3 (EPA and DHA) and ω-6 (ARA) fatty acids, concentrations were low in comparison to T. lutea. All Indonesian microalgal strains also contained the dicarboxylic acid (DCA), phthalic acid, which was not present in T. lutea

Effects of CO\u3csub\u3e2\u3c/sub\u3e on Growth Rate, C:N:P, and Fatty Acid Composition of Seven Marine Phytoplankton Species

Carbon dioxide (CO2) is the primary substrate for photosynthesis by the phytoplankton that form the base of the marine food web and mediate biogeochemical cycling of C and nutrient elements. Specific growth rate and elemental composition (C:N:P) were characterized for 7 cosmopolitan coastal and oceanic phytoplankton species (5 diatoms and 2 chlorophytes) using low density, nutrient-replete, semi-continuous culture experiments in which CO2 was manipulated to 4 levels ranging from post-bloom/glacial maxima (ppm) to geological maxima levels (\u3e2900 ppm). Specific growth rates at high CO2 were from 19 to 60% higher than in low CO2 treatments in 4 species and 44% lower in 1 species; there was no significant change in 2 species. Higher CO2 availability also resulted in elevated C:P and N:P molar ratios in Thalassiosira pseudonana (~60 to 90% higher), lower C:P and N:P molar ratios in 3 species (~20 to 50% lower), and no change in 3 species. Carbonate system-driven changes in growth rate did not necessarily result in changes in elemental composition, or vice versa. In a subset of 4 species for which fatty acid composition was examined, elevated CO2 did not affect the contribution of polyunsaturated fatty acids to total fatty acids significantly. These species show relatively little sensitivity between present day CO2 and predicted ocean acidification scenarios (year 2100). The results, however, demonstrate that CO2 availability at environmentally and geologically relevant scales can result in large changes in phytoplankton physiology, with potentially large feedbacks to ocean biogeochemical cycles and ecosystem structure

Attraction and repulsion of mobile wild organisms to finfish and shellfish aquaculture: a review

Knowledge of aquaculture–environment interactions is essential for the development of a sustainable aquaculture industry and efficient marine spatial planning. The effects of fish and shellfish farming on sessile wild populations, particularly infauna, have been studied intensively. Mobile fauna, including crustaceans, fish, birds and marine mammals, also interact with aquaculture operations, but the interactions are more complex and these animals may be attracted to (attraction) or show an aversion to (repulsion) farm operations with various degrees of effects. This review outlines the main mechanisms and effects of attraction and repulsion of wild animals to/from marine finfish cage and bivalve aquaculture, with a focus on effects on fisheries-related species. Effects considered in this review include those related to the provision of physical structure (farm infrastructure acting as fish aggregating devices (FADs) or artificial reefs (ARs), the provision of food (e.g. farmed animals, waste feed and faeces, fouling organisms associated with farm structures) and some farm activities (e.g. boating, cleaning). The reviews show that the distribution of mobile organisms associated with farming structures varies over various spatial (vertical and horizontal) and temporal scales (season, feeding time, day/night period). Attraction/repulsion mechanisms have a variety of direct and indirect effects on wild organisms at the level of individuals and populations and may have implication for the management of fisheries species and the ecosystem in the context of marine spatial planning. This review revealed considerable uncertainties regarding the long-term and ecosystem-wide consequences of these interactions. The use of modelling may help better understand consequences, but long-term studies are necessary to better elucidate effects

Immunomodulation in eastern oysters, \u3ci\u3eCrassostrea virginica\u3c/i\u3e, exposed to a PAH-contaminated, microphytobenthic diatom

The trophic transfer of sediment-associated pollutants is a growing concern in shellfish harvesting areas. Previous studies have examined the role of phytoplankton in the transport of organic contaminants to bivalve species, but little information on microphytobenthic communities and their role as contaminant vectors exists. Polycyclic aromatic hydrocarbons (PAHs) are organic compounds formed during natural and industrial processes; they are termed “persistent organic pollutants” because they are only slowly degraded by natural processes. This study examined the transfer of PAH compounds (naphthalene, pyrene, and benzo(a)pyrene) by a microphytobenthic diatom to the eastern oyster, a commercially important shellfish species, to determine if dietary accumulation is a route of contaminant exposure capable of inducing physiological responses. PAH compounds were adsorbed to a diatom culture (Nitzschia brevirostris) in a range of concentrations (5, 125, 625, and 1000 Mg L−1), and eastern oysters were exposed experimentally to the contaminated diatom cultures to assess possible effects upon oyster hemocytes and selected immune-defense functions. A preliminary experiment was designed to identify individual effects of several PAH compounds (naphthalene, pyrene, and benzo(a)pyrene) on hemocyte viability and phagocytic activity. Results from this experiment revealed that the most-toxic compound, benzo(a)pyrene, at the highest concentration, stimulated an increase in agranular hemocyte counts. A follow-up study examined the effects of benzo(a)pyrene on hemocyte viability, adhesion, phagocytosis, and reactive oxygen species (ROS). These studies showed the ability of this benthic diatom to transport PAHs to the eastern oyster and to cause immunomodulation. Hemocyte responses to dietary PAH exposure included an increase in circulating hemocytes and increased production of reactive oxygen species by these cells

Depth Selection and In Situ Validation for Offshore Mussel Aquaculture in Northeast United States Federal Waters

As mariculture progresses offshore in the US Exclusive Economic Zone, technical and ecological challenges need to be overcome, such as the choice of suitable sites that favor the production of target species. The offshore culture of blue mussels, Mytilus edulis, is performed with submerged longlines and mussels need to withstand more motion than on coastal sites. Temperature affects the ability of the byssus to adhere to farming rope, while chlorophyll concentration provides an estimation of food availability. Together, these are important factors in predicting the suitability of offshore mussel farms. To identify suitable depth of submersion for mussel ropes in New England federal waters, historical oceanographic data of temperature and chlorophyll a from 2005 to 2012 were used. The results suggest that mussel ropes were submerged during summer to a minimum depth of 15 m in northern and a 20-m depth in southern areas of New England where temperature is at a species-optimum and phytoplankton biomass is abundant. For the site offshore Massachusetts, in situ biodeposition measurements validated predicted depth, confirming satisfactory mussel performance. Promising local areas have shallow thermoclines, such as offshore Long Island, Cape Ann and New Hampshire. Recommended depths can be adjusted to future temperature increases associated with climate change

Transplant experiment to evaluate the feeding behaviour of the Atlantic ribbed mussel, Geukensia demissa, moved to a high inorganic seston area

6 pages, 1 figures, 2 tablesIn 2011-12, a field study demonstrated that ribbed mussels from two locations in the north-east Atlantic Coast of the USA used different feeding strategies to adapt to widely differing seston characteristics and achieve the same absorption efficiency. To investigate whether there was local, genetic adaptation of mussels in the two contrasting sites, we conducted a transplant experiment in 2012 in which mussels were moved from the high-plankton, low-inorganic waters of Milford Harbor, CT, to the high-inorganic, low-plankton waters of Hunts Point, Bronx, NY. Results showed that mussels from Milford adapted to the new, poorer-quality seston within 6 days of submersion in Hunts Point waters, which indicates that phenotypic plasticity in the species is sufficient to account for adaptability of the ribbed mussel to Hunts Point conditions. This adaptability makes the ribbed mussel a good candidate for environmental remediation technologies, such as nutrient bioextraction. © 2015 CSIROThis work was partially supported by a Research Associateship to the first author from the National Research Council with funding from Dr Michael Rubino of the NOAA National Aquaculture ProgramPeer Reviewe