The type of activated carbon determines how much dissolved organic carbon is removed from artificial seawater     

Stephen Spotte  Gary Adams 《Aquacultural Engineering》1984,3(3):207-220

Four granular activated carbons (GACs) made of different materials were tested for removal of dissolved organic carbon (DOC) from artificial seawater of a recirculated aquarium. After 70 days in a continuous flow experiment, comparative removal data (grams of GAC required to remove 1 g of DOC) were coconut shell (491), hardwood (84·4), anthracite (837) and bone char (383), indicating the superior performance of hardwood. Scanning electron microscopy showed that microbial colonization of a sample material (hardwood) was slight and occurred exclusively at the surface. Biological enhancement of GAC was considered to be unimportant as a mechanism for DOC removal.  相似文献   

Effects of oxygen supersaturation and temperature on juvenile greenlip, Haliotis laevigata Donovan, and blacklip, Haliotis rubra Leach, abalone     

James O Harris  Christopher M Burke  Stephen J Edwards  & Deon R Johns 《Aquaculture Research》2005,36(14):1400-1407

Growth and survival of juvenile greenlip (39.03 (SD 3.80) mm (n=524)) and blacklip (31.92 (SD 4.19) mm (n=531) abalone were investigated at high dissolved oxygen levels (95–120% saturation) between 17 and 19°C. Abalone were fed the same artificial diet and each species was contained in groups of approximately 30 individuals within triplicate tanks for each of six treatments and were exposed to flow through water adjusted to give experimental conditions for up to 75 days. Blacklip abalone held at 16.9°C and 97% oxygen saturation grew in shell length significantly faster than all other treatments of blacklip abalone held at 19°C, and significantly faster than blacklip abalone maintained at 111% oxygen saturation and 17.5°C. Both temperature and oxygen saturation significantly affected the survival of this species. Blacklip abalone held at 19°C had significantly lower survival for both 96% oxygen saturation and 120% oxygen saturation, compared with blacklip abalone maintained at either 110% oxygen saturation and 19°C, or for any 17°C treatment. No significant differences were noted for greenlip abalone within the range tested in terms of growth rate, food consumption rate or survival, indicating that greenlip abalone tolerated these conditions better than did blacklip abalone.  相似文献   

Marine research,resources and conservation in the Azores     

Ricardo Serro Santos  Stephen Hawkins  Luis Rocha Monteiro  Mrio Alves  Eduardo Jos Isidro 《水产资源保护:海洋与淡水生态系统》1995,5(4):311-354

• 1 A history of marine research on the Azores is outlined. Until two decades ago most oceanic and littoral marine studies had been carried out by foreign scientists. Studies by Azorean scientists started to increase in the early 1980s when the University of the Azores was created.
• 2 Ocean circulation in this part of the Atlantic is described as a background for biogeography and diversity. The picture emerges that Azores is a ?meeting point’? for shallow water marine fauna and flora of different origins.
• 3 The species composition of one of the best studied groups of organisms, the fish, is compared between locations in the northeastern Atlantic. The work on fish is also compared with other well studied groups (algae and hydroids) to highlight the interest of the Azores as a natural biogeographical experiment.
• 4 Studies of marine resources began less than two decades ago. The development of demersal fisheries is described focusing on the switch from small-scale artisanal fishing to more commercial fisheries.
• 5 Conservation of species and legislation in force for molluscs, crustaceans, fishes, marine turtles, seabirds and marine mammals are summarized.
• 6 Protected marine areas already designated are defined, as well as new areas recommended.
• 7 The paper concludes with a discussion of current threats and future management strategies.

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PROBIT analysis predicts hatching rates of brine shrimp Artemia sp. cysts     

Stephen Spotte  Gary Adams  Paul E. Stake 《Aquacultural Engineering》1984,3(1):1-13

Thirty replicates of San Francisco Bay brine shrimp Artemia sp. cysts from one lot were weighed to 0·01 mg. The mean mass of a single cyst was 2·597 μg (±0·040 μg, 95% confidence level). Batches of 1 g from the same lot were hatched in the laboratory, and fraction hatched versus time data were fitted to a nonlinear curve using PROBIT analysis. Median time of hatch was 24·8 h with a standard error of ±3·92 h. Cysts and nauplii in 1-ml aliquots were pipetted at regular intervals and counted under a dissecting microscope. The number of cysts pipetted at the beginning of the experiment was 19% less than estimates based on the known number per volume of hatching medium, indicating that hatching data derived from pipetting procedures may contain large sampling errors. PROBIT analysis allows fraction hatched to be predicted when a particular lot of cysts is hatched under controlled conditions.  相似文献   

Effect of Water Exchange Rate on Production, Water Quality, Effluent Characteristics and Nitrogen Budgets of Intensive Shrimp Ponds   总被引：9，自引：0，他引：9  

J. Stephen  Hopkins  Richard D.  Hamilton II  Paul A.  Sandier  Craig L.  Browdy Alvin D.  Stokes 《Journal of the World Aquaculture Society》1993,24(3):304-320

Water exchange is routinely used in shrimp culture. However, there are few, if any, systematic investigations upon which to base exchange rates. Furthermore, environmental impacts of pond effluent threaten to hinder further development of shrimp farming in the U.S. The present study was designed to determine effects of normal (25.0%/d), reduced (2.5%/d) and no (0%/d) water exchange on water quality and production in intensive shrimp ponds stocked with Penaeus setiferus at 44 postlarvae/m². Additional no-exchange ponds were stocked with 22 and 66 postlarvae/m² to explore density effects. Water exchange rates and stocking density influenced most water quality parameters measured, including dissolved oxygen, pH, ammonia, nitrite, nitrate, Kjeldahl nitrogen, soluble orthophosphate, biochemical oxygen demand, phytoplankton and salinity. Reduced-exchange and no-exchange treatments resulted in reduced potential for environmental impact. Mass balance of nitrogen for the system indicates that 13–46% of nitrogen input via feed is lost through nitrification and atmospheric diffusion. Growth and survival were excellent in ponds with normal exchange, reduced exchange, and a combination of low density with no water exchange. A combination of higher stocking density and no water exchange resulted in mass mortalities. Mortalities could not be attributed to a toxic effect of any one water quality parameter. Production was 6,400 kg/ha/crop with moderate stocking density (44/m²) and reduced (2.5%/d) water exchange and 3,200 kg/ha/crop with lower stocking density (22/m²) and no water exchange. Results indicate that typical water exchange rates used in intensive shrimp farms may be drastically reduced resulting in a cost savings to farms and reduced potential for environmental impact from effluent.  相似文献   

A Lightweight, Portable Fish-trap for Use in Small Lowland Rivers     

Stephen Swales 《Aquaculture Research》1981,12(3):83-88

The construction and installation of a modified fyke-net trap, designed for use in small lowland rivers, is described. The trap is inexpensive to construct, lightweight and very portable. Small-scale trials, with traps installed in the R. Perry, demonstrated their effectiveness in capturing a wide range of size-classes of coarse fish species. The trap can be a useful tool in sampling and movement studies involving coarse fish species in small lowland rivers.  相似文献   

Diagnosis and management of small-scale fisheries in developing countries   总被引：2，自引：0，他引：2  

Neil L Andrew  Christophe Béné  Stephen J Hall  Edward H Allison  Simon Heck  & Blake D Ratner 《Fish and Fisheries》2007,8(3):227-240

Small‐scale fisheries (SSF) make important but undervalued contributions to the economies of some of the world’s poorest countries. They also provide much of the animal protein needed by societies in which food security remains a pressing issue. Assessment and management of these fisheries is usually inadequate or absent and they continue to fall short of their potential as engines for development and social change. In this study, we bring together existing theory and methods to suggest a general scheme for diagnosing and managing SSF. This approach can be adapted to accommodate the diversity of these fisheries in the developing world. Many threats and solutions to the problems that beset SSF come from outside the domain of the fishery. Significant improvements in prospects for fisheries will require major changes in societal priorities and values, with consequent improvements in policy and governance. Changes in development policy and science reflect these imperatives but there remains a need for intra‐sectoral management that builds resilience and reduces vulnerability to those forces beyond the influence of small‐scale fishers.  相似文献   

Integration of independent component analysis with near infrared spectroscopy for evaluation of rice freshness   总被引：1，自引：0，他引：1  

Yung-Kun Chuang  Yi-Ping Hu  I-Chang Yang  Stephen R. Delwiche  Yangming Martin Lo  Chao-Yin Tsai  Suming Chen 《Journal of Cereal Science》2014

The storage time and conditions of rice has an enormous effect on its appearance, flavor, and quality of the nutrients; and the acidity of rice usually increases with prolonged storage. Therefore, evaluation of freshness is an important issue for rice quality. In this study, the NIR (near infrared) spectra combined with independent component analysis (ICA) technique was used to evaluate the rice freshness. A total of 180 white rice samples were collected from 6 crop seasons for the purpose of developing an ICA-NIR based procedure for rice freshness as quantified by pH values. Values of pH were determined by a BTB-MR (bromothymol blue – methyl red) method. The best calibration model of white rice was developed using the smoothed first derivative spectra, five ICs and cross-validation; the results indicated that r² (coefficient of determination) = 0.924, and in units of pH, SEC (standard error of calibration) = 0.145, SEP (standard error of prediction) = 0.146, bias = 0.001, and RPD (residual predictive deviation) = 3.65. Freshness of white rice could be distinguished either visually by a 3-dimensional diagram composed from ICs 2, 3 and 4, or statistically by a calibration model. The results show that ICA with NIR has the potential to be adopted as an effective method for evaluating rice freshness.  相似文献   

Morphological development of post hatch larval goldlined seabream Rhabdosargus sarba (Forskål, 1775)     

Fahad S Ibrahim  Krishen J Rana  James Stephen Goddard  & Issa S Al Amri 《Aquaculture Research》2006,37(12):1156-1164

Ultrastructural changes in Rhabdosargus sarba larva in early life history were investigated. At hatching, the digestive system was histologically undifferentiated. The digestive tract was a straight tube attached to the dorsal end of the yolk‐sac and was not connected to either the mouth or the anus. The layer of gut epithelium at some regions of the luminal surface was straight and microvilli were not present. These straight borders were not observed at 1 day post hatching (DPH) onwards as microvilli increased in number on the luminal surface and became more regular. At 2 DPH, the digestive system was well differentiated and the separation of the mid‐ and hindgut by the intestino‐rectal valve became more advanced. At 0 DPH, the eye was spherical and the retina had a zonation with undifferentiated cells. The eye also lacked differentiated photoreceptors (PR). The retinal PRs increased in length and in number as the yolk‐sac was absorbed. By 2 DPH, the eye was fully pigmented, suggesting that the larval vision system was functional. The larvae had a pure cone retina at the onset of exogenous feeding. Morphological and functional differentiation of the digestive tract and the eye of the larvae preceded the completion of yolk and oil globule absorption. The oil globule was exhausted at 4 DPH and at 2 DPH, the yolk‐sac was completely absorbed. Food particles were observed at 3 DPH. Food particle ingestion and absorption of the yolk‐sac were observed as vision became fully functional.  相似文献   

Fluvial maintenance operations in managed alluvial rivers     

Stephen E. Darby  Colin R. Thorne 《水产资源保护:海洋与淡水生态系统》1995,5(1):37-54

• 1 Fluvial maintenance is frequently undertaken to preserve the flood capacity, visual amenity, conservation value and geomorphic stability of managed river channels. Maintenance tasks include the management of both riparian and in-channel vegetation and maintenance dredging.
• 2 Riparian vegetation is traditionally managed by physical methods such as cutting of grasses or removal of trees. Less environmentally severe alternative practices include grazing or shading for grasses, and practices such as pollarding or coppicing for trees.
• 3 While a range of alternative maintenance practices, with varying environmental impact, are usually available for river managers to select, the potential for improving maintenance practices varies according to the particular task considered and the constraints imposed by the need to reach and maintain the target standard of service in terms of flood defence and land drainage.
• 4 This review shows that economic and environmental impacts associated with fluvial maintenance operations may be reduced at three scales. First, at the smallest scale, it is shown that there is often potential for improving the local operational efficiency of individual fluvial maintenance tasks. Second, it may be possible to reduce the intensity of maintenance in channel reaches which are presently over-serviced. Third, at the largest scale, it is shown that efficient maintenance is best achieved within the framework of Integrated Basin Management, and by giving appropriate consideration to future maintenance requirements at the design stage of new projects to reduce the overall need for fluvial maintenance. Examples of the way in which these policies may be implemented to reduce environmental impact without compromising engineering objectives are illustrated through case studies from the UK and the USA.

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