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1.
Perkinsus spp. have been detected in various bivalve species from north‐east Brazil. Santa Catarina is a South Brasil state with the highest national oyster production. Considering the pathogenicity of some Perkinsus spp., a study was carried out to survey perkinsosis in two oyster species cultured in this State, the mangrove oyster Crassostrea gasar and the Pacific oyster Crassostrea gigas. Sampling involved eight sites along the state coast, and oyster sampling was collected during the period between January 2013 and December 2014. For the detection of Perkinsus, Ray's fluid thioglycollate medium (RFTM) and histology were used, and for the identification of the species, PCR and DNA sequencing were used. Perkinsus spp. was found by RFTM in C. gigas and C. gasar from São Francisco do Sul. This pathology was also detected in C. gasar from Balneário Barra do Sul both, by RFTM and histology. Perkinsus marinus was identified in C. gigas and C. gasar from São Francisco do Sul and Perkinsus beihaiensis in C. gasar from Balneário Barra do Sul. This is the first report of P. marinus in C. gigas from South America. Results of this preliminary study suggest that both oyster species tolerate the species of Perkinsus identified, without suffering heavy lesions.  相似文献   

2.
We report the results of survival and growth in size and dry mass of spat of the Caribbean pearl oyster Pinctada imbricata cultivated under outdoor (field culture) and indoor (Laboratory) conditions. Field group fed on environmental seston. Laboratory groups were fed with mono, binary and ternary mixtures of three cultivated algae: Isochrysis galbana (Ig), Tetraselmis chuii (Ig) and the Chaetoceros sp. (Ch‐A, isolated from north‐eastern Venezuela). After 30 days of trial, fatty acid profiles of spat were determined along with growth in length and height shell, adductor muscle and soft tissue dry mass. During the field grow‐out phase (field culture), samplings were performed at days 1, 15 and 30 to measure environmental variables of phytoplankton biomass (chlorophyll a), dissolved oxygen, seston, temperature and salinity. A significant increase in size and soft tissue mass occurred in spat fed the diets including the tropical diatom (Chaetoceros sp.). In contrast, monoalgal diets of Tc and Ig yielded no significant differences in size and mass of spat, compared with the field culture. These results suggest that nutritional requirements of cultivated spat for specific fatty acids of physiological importance for marine bivalves, such as: 16:0, 16:1n‐7, 18:2n‐6, 20:4n‐6, 18:3n‐3 and 20:5n‐3, were satisfied from microalgal diets with Ch‐A, alone or in combination, compared with spat fed from the field culture.  相似文献   

3.
In Vietnam, the production of striped catfish Pangasianodon hypophthalmus S. reached more than 1.2 millions of tons in 2014 and is mainly gathered in the Mekong Delta (South Vietnam). A survey was carried out during the dry season 2013 (March–April) and rainy season 2014 (July–August) in 12 fish farms of the lower (Tra Vinh Province) and higher (Can Tho Province) Mekong River Delta. This study allowed drawing up current key osmoregulatory and innate immune parameters of striped catfish in aquaculture depending on the geographical location, particularly the proximity to the River Mekong Estuary and the seasonal surface runoff. In the dry season, plasma osmolality was positively correlated with salinity. Gill Na+K+ ATPase dropped in the rainy season, while kidney Na+K+ ATPase remained stable. Abundance of immune blood cells, especially thrombocytes and monocytes, tended to increase in farms located in tidal area. Production of reactive oxygen species in the spleen, kidney lysozyme activity and plasma complement activity did not vary whatever the season or the proximity to the estuary. Plasma lysozyme activity was 50-fold higher than in kidney and increased in the rainy season as well as in tidal sites. Kidney complement activity decreased in the dry season, especially in tidal sites. In conclusion, regarding key osmoregulatory and immune factors, striped catfish farms located in the Mekong Delta may be affected by seasonal and regional salinity and runoff fluctuations.  相似文献   

4.
The fatty acid and sterol composition of the oyster Pinctada margaritifera during oogenesis and in eggs was analysed. No major differences were observed during oogenesis, but the egg composition was significantly different from that of gonads. The amount of saturated fatty acids was the highest in eggs and the C16:0 predominant (P<5%); by contrast, the amount of 22:6(n‐3) was significantly lower (P<5%) than in gonads. No major differences were observed for the polar lipid (PL) composition during oogenesis. The main free sterols in gonads and eggs were cholesterol and brassicasterol. Among free sterols, the proportion of cholesterol diminished continuously from the beginning to the end of gonad maturation, and this decrease persisted in eggs after spawning. Cholesterol represented 40% to 55% of the sterol ester encountered in gonad and eggs. This study allowed us to investigate the fatty acid and sterol composition during oogenesis of the pearl oyster P. margaritifera, leading to a clearer understanding of the nutritional requirements of pearl oyster during the reproduction process.  相似文献   

5.
de Macedo-Soares PHM, Petry AC, Farjalla VF, Caramaschi EP. Hydrological connectivity in coastal inland systems: lessons from a Neotropical fish metacommunity.
Ecology of Freshwater Fish 2010: 19: 7–18. © 2009 John Wiley & Sons A/S
Abstract –  We assessed the influence of hydrological connectivity in structuring fish communities through seasonal samplings of environmental variables and fishes in a coastal lagoon and associated pools in the Restinga de Jurubatiba National Park, Brazil. Community structure attributes such as species richness, numerical density and biomass, Shannon–Wiener diversity index and evenness were compared between periods of the lowest and highest hydrological connectivity, while the environmental gradient and fish zonation were explored through ordination techniques. The greater hydrological connectivity established in the rainy season promoted the homogenisation of most environmental variables and fish species, which differed markedly from the arrangement observed in the dry season. Despite variation in fish species composition, community attributes showed non-significant differences between the dry and rainy seasons. The patterns of composition and numerical density in pools were strongly influenced by local factors, especially salinity, dissolved oxygen, total phosphorous concentration and water colour in the dry season, in addition to total nitrogen concentration and depth in the rainy season. Comparable to the role played by flood pulses in river-floodplain systems, the hydrological connectivity in these tropical coastal waterbodies seems to strongly influence fish community structure, and, therefore to determine regional biodiversity.  相似文献   

6.
Winter mortality in hatchery reared oyster spat (Ostrea edulis) that received three different diets during the summer period was investigated. Oysters fed a natural type diet had a winter mortality of 18.3 ± 6.3% while oysters fed cultivated algae (a mixture of Tetraselmis suecica, Isochrysis galbana and Chaetoceros muelleri) had a mortality of 73.0 ± 9.7%. A group of oysters fed a mix between the two diets had a mortality of 54.7 ± 10.6%. Tissue samples were taken at the start of the experiment, after the summer period and after the winter period in order to determine growth and the content of glycogen and fatty acids. The glycogen content decreased for all groups during the winter but the decrease was highest in oysters fed the natural diet. This group also contained the largest variety of fatty acids, but there was no difference in the content of the essential fatty acids EPA, DPA and DHA between the groups. It is concluded that transplantation of spat to the sea in spring and early summer may reduce winter mortality since the feeding period on a more varied natural algal diet is prolonged compared to transplantation of spat later in the season.  相似文献   

7.
A large part of the extensive aquaculture in Tunisia was based on the transfer of mullet fry from the marine coastal areas to the continental fresh water lakes, the aim of this work is the monitoring of the changes made in the lipid composition of Mugil cephalus fry according to salinity and temperature acclimation. Fish acclimated to 14 °C and 0.5 psu salinity, contained 55% less total fatty acid than those acclimated to the seawater at the same temperature. Low salinity induces an increase in the percentage of some polyunsaturated fatty acid such as the 22:5 (n-3), the 22:6 (n-3) and the 20:4 (n-6), as a result of change in the level of triacylglycerol content or the activation in the synthesis of those fatty acids. The transition of the acclimation temperature from 26 to 14 °C in seawater is followed by a 215% increase in the amount of total fatty acids in the fourth week of acclimation. The total fatty acid levels of all fish at 1 week were higher than most values at 4 weeks. There was an increase of polyunsaturated fatty acids percentages due to the decrease of the temperature at the low salinity. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

8.
The polyunsaturated fatty acids of the n-3 family associated with fish and fish oils have been shown to have beneficial effects on prevention of heart disease in humans. However, in considering the potential health benefits of fish oil in human health, it is important to realize that the fatty acid composition and total lipid content of fish vary greatly. These variations may be due to species differences or variations within a species due to temperature, diet, developmental stage, sex or seasonal differences. The purpose of the study described here was to determine the effects of season, size class, and sex on the Occurrence of individual fatty acids in striped bass (Morone saxrrtilis). Fish were collected in June, July, August, September, and October. Filets with skin were analyzed for total lipid content. Methyl esters of fatty acids were separated and identified using capillary gas chromatography. Total mean lipid varied from as low as 12% to as high as 30%. There were no significant changes in total crude lipid content due to month collected or sex. However, total lipid content of filets increased significantly (P ≤ 0.05) as size increased. The fatty acids 18:1n–9 and 16:0 made up the majority (62%) of the fatty acids present in any season, size class, or sex. The monounsaturated fatty acids dominated in all fish. There were no significant differences in individual fatty acids due to sex. However, fish size had a significant influence on fatty acid composition. Overall, saturated fatty acids decreased as size increased, while polyunsaturated fatty acids increased or remained constant. There were no significant changes in mean percent saturated or monounsaturated fatty acids with respect to month when controlling for size. However, total percent polyunsaturated fatty acids decreased significantly in October compared to August and September. This overall decrease was due mainly to a decrease in 22:6n–3. Conversely there was a significant increase in 16:11n–9 in October. All other fatty acids remained constant. When data from this study were compared to fatty acid data from the literature, striped bass was not as good a source of 20:5n–3 and 22:61n–3 as sardines, anchovies or mackerel.  相似文献   

9.
The findings of this study provide useful insights into the key aspects of fish cage farming to be considered during setting and overall management of multi-purpose water resources so as to maximise their aquacultural potential. The study was conducted in Machakos District, Kenya, to characterise limnochemistry and algal composition of three small man-made reservoirs Ngeki, Ngei and Kavovi, used for cage culture of Nile tilapia (Oreochromis niloticus). In Ngeki, the open water was compared with areas in between the cages and significant differences in dissolved oxygen were found. For N, P and chlorophyll-a, no differences were noticed. In all the reservoirs, temporal variations were noticed for all parameters except NO3N and NH4N. Peak concentrations of nutrients occurred during the rainy season with lower values in the dry season (below detectable limits for SRP). All reservoirs were classified as hyper-eutrophic with a strong positive correlation between chlorophyll-a and TP. Algal abundances changed with season. Chlorophyta dominated at the start of the rainy season, while cyanobacteria prevailed at the onset of thermal stratification. Diatoms prevailed in the dry season but were notably absent in the rainy season. It was concluded that all the reservoirs are suitable for cage culture of Nile tilapia, but this should be undertaken with caution considering critical periods when anoxic conditions may occur.  相似文献   

10.
为了阐明盐度胁迫对金钱鱼(Scatophagus argus)代谢和生殖的影响,采用RNA-seq技术对低盐组(5)、对照组(25)和高盐组(35)处理40 d后的2龄性成熟金钱鱼卵巢进行转录组分析。结果发现,金钱鱼卵巢转录组测序获得raw reads共398681318,clean reads共396910398。从低盐胁迫相对对照组(5 vs 25)和高盐胁迫相对对照组(35 vs 25)中分别筛选到373个和874个差异表达基因(DEGs)。与对照组相比,低盐胁迫后氨基酸代谢相关基因(sds、bhmt)和脂肪酸代谢相关基因(pnpla2)显著下调;高盐胁迫后pgr、cyp17a1和ers1等生殖相关基因显著下调。KEGG通路富集分析发现,低盐胁迫组相对对照组显著富集与代谢相关的通路为半胱氨酸和甲硫氨酸代谢,缬氨酸、亮氨酸和异亮氨酸生物合成代谢,脂肪酸生物合成,脂肪酸代谢,皮质醇的合成和分泌,醛固酮的合成和分泌,脂肪细胞脂解的调节等;高盐胁迫组相对对照组中显著富集的与生殖相关的通路为雌激素信号传导通路。这些结果表明,氨基酸和脂肪酸的代谢调控可能在金钱鱼卵巢的低渗透压调节中起重要作用...  相似文献   

11.
Fatty material from Nile perch belly flaps, a major processing by‐product, was assessed for variation in fat content, fatty acid composition, vitamin A content, and level of contaminants in relation to capture site and season. Nile perch from Lake Victoria had higher material yield and omega-3 fatty acids (FAs) but lower content of vitamin A than those from Lake Albert. Levels of omega-3 FAs (4.36–20.20%) and vitamin A (2.83–7.88 mg/100 g of oil) were generally high. Levels of lead and cadmium showed significant variation with site. Material weight and vitamin A contents were higher, whereas FAs were lower in fish captured during the dry season than those in the wet season.  相似文献   

12.
The study was designed to assess the seasonal variations in the quality and lipid profile of mussel meat (Mytilus galloprovincialis) harvested along the Bulgarian coast of the Black Sea. The trial period lasted from June to October, and the sampling was carried out in the area of Varna Bay. Technological quality of the mussels was determined by measuring the water holding capacity (WHC) and cooking and roasting losses. Proximate composition, total aerobic plate count, and fatty acid analysis were carried out. Technological parameters and nutritional quality of the mussel meat were strongly affected by the season. During the summer, the mussels had higher mass, meat content, and meat yield (p < 0.001) compared to the early autumn, which corresponds to the lowest protein content during this season. Lipid profile showed seasonal variations in both individual and total fatty acid amounts (p < 0.001). Saturated fatty acids (SFA) had the highest content in summer, while monounsaturated fatty acids (MUFA) decreased gradually until the autumn. The content of polyunsaturated fatty acids (PUFA) reached its peak in October, contributing to the most favorable values of the nutritional indices of lipids in the early autumn.  相似文献   

13.
Salinity fluctuation is an important factor affecting outdoor microalgae culture. This investigation examined the effect of salinity change (Tr‐1:35–15 g/L, Tr‐2:35–25 g/L, Tr‐3:35–35 g/L, Tr‐4:35–45 g/L, and Tr‐5:35–55 g/L) on growth and the biochemical composition of Nannochloropsis oculata, a candidate for biodiesel production in indoor photo‐bioreactors. Results showed that the algae increased in absorbency and dry biomass as salinity decreased. When the salinity increased, the specific growth rate (SGR) of the algae decreased significantly. The salinity stress also affected the pigments of the algae, the chlorophyll‐a, and carotenoid contents of the algae which decreased with the increase of salinity from 45 to 55 g/L. The fatty acid methyl esters (FAME) content (% of dry biomass) increased with the increase of salinity (e.g., Tr‐4 and Tr‐5). The algae was rich in C16:0 (palmitic acid), C16:1n‐7 (palmitoleic acid), and C20:5n‐3 (eicosapentaenoic acid), and C16:0 content increased with decreasing salinity from 35 to 15 g/L, but C16:1n‐7 content was high in all the treatments ranging from 25.25 ± 1.42% in Tr‐1 to 27.05 ± 1.13% in Tr‐5.  相似文献   

14.
ABSTRACT

Interannual and seasonal (premonsoon, monsoon, and postmonsoon) variability in the lipid, fatty acids, and total cholesterol content of ribbon fish, Trichiurus lepturus were determined for a period of 4 years (2008–2011) along the southwest (SW) and southeast (SE) coasts of India. The lipidic compositions were studied along with chlorophyll-a concentration and sea surface temperature (SST) data obtained from MODIS and Sea WiFS. The lipid content shows seasonal fluctuations with higher values in the postmonsoon season along the SE coast and during the monsoon in the SW coast. Among polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA) dominated over eicosapentaenoic acid (EPA) throughout the seasons except in winter on the SE coast. The health indices such as atherogenic/thrombogenicity indices, total cholesterol, and hypocholesterolemic/hypercholesterolemic ratio of ribbon fish were found to be ideal, which contributed toward its parameters to be qualified as a potential health food.  相似文献   

15.
近年来莱州湾盐度分布及变化   总被引：7，自引：0，他引：7  
刘晓静  靳洋 《齐鲁渔业》1998,15(5):46-47
１９９５～１９９７年枯水期和丰水期,进行了莱州湾１４个站位的盐度监测,结果：１９９５～１９９６年莱州湾盐度西低东高,层次分明１９９７年盐度大幅度升高,仅出现一条盐度３０的等值线,这主要是由气候干旱,黄河入海径流不断减少,断流时间逐年增加所致。  相似文献   

16.
闽东海域银鲳亲鱼性腺发育后期脂类及脂肪酸蓄积特点   总被引：1，自引：0，他引：1  
脂肪和脂肪酸是海水鱼类早期生长发育的重要结构物质和能量来源。亲鱼的脂肪和脂肪酸储备影响其繁殖性能和早期仔鱼的发育。为了获知银鲳亲鱼性腺发育后期脂类及脂肪酸蓄积特点,本研究采用氯仿甲醇法及气相色谱法定量检测了繁殖季节闽东海域野生银鲳亲鱼不同组织的总脂肪及脂肪酸含量。结果表明:亲鱼卵巢、精巢、肝脏和肌肉的总脂肪含量差异显著。卵巢、精巢、肝脏和肌肉的总脂含量分别为:35.76%,15.11%,22.07%和22.14%(占组织干重)。极性脂肪占总脂肪的比例在精巢中最高,其次为肝脏和卵巢,在肌肉中最低。性腺从Ⅳ期发育到Ⅴ期,雌鱼卵巢总脂肪和中性脂肪含量显著增加,雄鱼肌肉极性脂肪含量显著降低。中性脂肪中卵巢的20∶5n-3(EPA,2.25~3.87 mg/g)、22∶6n-3(DHA,6.71~13.03mg/g)和高不饱和脂肪酸(HUFAs,17.20~29.64 mg/g)含量最高,极性脂肪中精巢的EPA(0.38~0.27 mg/g)和DHA(3.12~3.59 mg/g)含量最高。性腺中n-3/n-6比值显著高于肝脏和肌肉中。随着卵巢发育,DHA等必需脂肪酸在雌鱼不同组织及同一组织不同脂肪类别之间存在转移现象。研究表明,银鲳亲鱼各组织的总脂肪含量、总脂肪组成及脂肪酸绝对含量(mg/g干物质)具有组织特异性,随着性腺发育,必需脂肪酸总体上表现为由肌肉和肝脏向性腺中转移,且性腺中脂肪酸的变化主要发生在中性脂肪中。  相似文献   

17.
  • 1. Although the Doñana National Park is given the highest degree of environmental protection in Spain, it is likely that groundwater discharge to several ponds within the Biological Reserve has been damaged by abstraction to a tourist resort located less than 1 km away.
  • 2. Hydrological changes were monitored over 16 years (1 October 1989 to 30 September 2005) by recording the shallow water table of six temporary ponds at 1–8-week intervals, and the duration of pond wet phase (or hydroperiod) during each hydrological cycle.
  • 3. The average rainfall for the study period was 563.2 mm, and included 6 wet, 5 moderate, and 5 dry years in a seemingly random sequence. The average rainy season extended from October until the end of March, while the dry season occupied the rest of the year.
  • 4. The water table generally oscillated following this alternation of rainy and dry seasons, but this fluctuation was minimal during dry years, and even failed to occur at some ponds.
  • 5. Since 1998/99, the average hydroperiod has shortened by 3 months at Charco del Toro pond, and by almost 2 months at Brezo pond, while the rest of the ponds exhibited a reduction of less than 1 month.
  • 6. Vegetation changed in the ponds between May 1990 and 2005. Total plant cover increased (range of increase: 16–65%), and species richness decreased in all ponds (range of species loss: 4–18).
  • 7. The reduction in the hydroperiod probably enhanced the growth of a few woody plants to the detriment of flooding-dependent species as the cover of Pinus pinea increased nearly fourfold at Brezo pond, while that of Scirpus lacustris was halved at Charco del Toro pond.
  • 8. The pumping area for the nearby tourist resort should be relocated, and a specific management strategy should be developed in order to prevent further damage to the ponds.
Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

18.
This study evaluated the lipid content and fatty acid (FA) profile of the hepatopancreas, ovaries and tail muscle of Lysmata amboinensis broodstock, as well as newly hatched larvae subjected to a period of starvation or feed from hatch to Zoea 2. The hepatopancreas had a high lipid content, confirming its role as a process and storage organ in L. amboinensis. Lipids were also a major component of ovarian dry weight, in agreement with reports on other crustaceans during maturation. The tail muscle, being a functional rather than a storage organ, contained low total lipids and was the tissue that closely resembled the FA profile of the newly hatched larvae. Saturated fatty acids (SFAs) and highly unsaturated fatty acids (HUFAs) were the most abundant components of the lipid profiles in broodstock and larvae. The HUFAs docosahexaenoic and eicosapentaenoic were preferentially retained during nutritional stress, confirming their importance for marine cleaner shrimp during early larval development. It appeared polyunsaturated fatty acid and HUFA requirements were met through the larval diet. The SFAs stearic and palmitic were abundant in adult tissues and larvae, whereas monounsaturated fatty acids may have been preferentially catabolized to meet energetic and metabolic larval requirements.  相似文献   

19.
Pavlova lutheri was cultivated in carboys using batch technique and in a flat alveolar photobioreactor (FAP), using initially batch and then semi‐continuous techniques. Growth and productivity of the cultures were compared and their nutritional quality was assessed by analysing their biochemical composition (gross composition, fatty acids and sterols) and by evaluating their food value for Pacific oyster (Crassostrea gigas) larvae as bispecific diet in association with Chaetoceros calcitrans forma pumilum. The highest productivity was achieved with the FAP operating in semi‐continuous mode. Gross composition of P. lutheri was similar in all cultures, while cellular organic matter content of the microalga grown in FAP in semi‐continuous mode was lower. Significant differences in fatty acid content were detected with respect to the n‐6 polyunsaturated fatty acid fraction, which was lower in cells cultivated in the FAP in semi‐continuous mode. As concerns the main individual fatty acids, docosahexaenoic acid (DHA) content was higher in cells cultivated in the photobioreactor in batch mode than in carboys. The neutral lipid fraction contained seven principal sterols and the comparison among the cultures evidenced different proportions and different patterns. No differences were observed among larvae fed diets containing P. lutheri grown in carboys or in the FAP.  相似文献   

20.
The mangrove oyster, Crassostrea gasar, constitutes an important source of animal protein among some communities in the Lagos area. This paper summarises present knowledge of the fishery of the mangrove oyster in the Lagos area, highlights its prospects, and suggests how oyster production for consumption can be improved.  相似文献   

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