厚壳贻贝的同化率及其生物沉积作用

2001年3～9月在青岛海区自然养殖状态下,利用沉积物收集器测定厚壳贻贝(Mytiluscrassitesta)的生物沉积及其对物质的输运,并采用灰分比例法计算厚壳贻贝的同化率。结果显示,厚壳贻贝的同化率分别为:小个体(壳长42～49mm)43 2%～59 9%、中等个体(壳长54～60mm)41 3%～56 1%、大个体(壳长65～74mm)47 6%～53 5%,平均值分别为51 6%、49 5%和52 5%。厚壳贻贝通过生物沉积作用加速海洋中颗粒物质的沉积,生物沉积率随个体的增大而增加,呈正相关关系,分别为:小个体[(42 3±4 4)～(77 9±10 8)]mg·ind-1·d-1,中等个体[(68 5±5 8)～(134 1±12 7)]mg·ind-1·d-1和大个体[(83 4±10 4)～(167 1±10 8)]mg·ind-1·d-1。海水温度和环境中饵料数量是影响厚壳贻贝的生物沉积的重要因子。     

不同温度下刺参对贝类生物性沉积物的摄食与吸收

以常规实验生态方法 ,研究了不同温度下不同规格刺参对贝类生物性沉积物的摄食与吸收 ,得出了实验过程中 ,平均水温为 13.2 0～ 2 2 .30℃时 ,不同规格刺参对贝类生物沉积物平均摄食率 (g/ g .h)依次为大 (0 .0 0 32 4 )、中 (0 .0 0 6 4 8)、小 (0 .0 0 95 9)。另外 ,不同规格刺参对贝类生物沉积物平均吸收率依大(7.32 % )、中 (13.4 9% )、小 (17.6 1% )。其中 ,温度在 15 .13℃时 ,大规格刺参的吸收率达最大 ,为15 .32 % ;当温度上升到 2 3.2 0℃ ,中、小两种规格刺参吸收率达最高 ,依次为中 (2 3.5 6 % )、小 (2 6 .4 9% )。刺参对沉积物中有机物的吸收与利用 ,降低了水底有机物的含量 ,可有效抑制水体有害物质的积累及产生。     

An assessment of the use of pigment content as a feeding index in oysters

The content of acetone-extractable material in samples of Crassostrea gigas Thunberg collected from a field population over a period of 20 months is reported. Values are compared with those obtained in laboratory studies of fed and starved Ostrea edulis L. The acetone-extractable content is shown to be capable of marked change over a short time period. Caution is advised in the use of such data as a quantitative feeding index in field sampling.     

The efficiency and condition of oysters and macroalgae used as biological filters of shrimp pond effluent

Current shrimp pond management practices generally result in elevated concentrations of nutrients, suspended solids, bacteria and phytoplankton compared with the influent water. Concerns about adverse environmental impacts caused by discharging pond effluent directly into adjacent waterways have prompted the search for cost‐effective methods of effluent treatment. One potential method of effluent treatment is the use of ponds or raceways stocked with plants or animals that act as natural biofilters by removing waste nutrients. In addition to improving effluent water quality prior to discharge, the use of natural biofilters provides a method for capturing otherwise wasted nutrients. This study examined the potential of the native oyster, Saccostrea commercialis (Iredale and Roughley) and macroalgae, Gracilaria edulis (Gmelin) Silva to improve effluent water quality from a commercial Penaeus japonicus (Bate) shrimp farm. A system of raceways was constructed to permit recirculation of the effluent through the oysters to maximize the filtration of bacteria, phytoplankton and total suspended solids. A series of experiments was conducted to test the ability of oysters and macroalgae to improve effluent water quality in a flow‐through system compared with a recirculating system. In the flow‐through system, oysters reduced the concentration of bacteria to 35% of the initial concentration, chlorophyll a to 39%, total particulates (2.28–35.2 µm) to 29%, total nitrogen to 66% and total phosphorus to 56%. Under the recirculating flow regime, the ability of the oysters to improve water quality was significantly enhanced. After four circuits, total bacterial numbers were reduced to 12%, chlorophyll a to 4%, and total suspended solids to 16%. Efforts to increase biofiltration by adding additional layers of oyster trays and macroalgae‐filled mesh bags resulted in fouling of the lower layers causing the death of oysters and senescence of macroalgae. Supplementary laboratory experiments were designed to examine the effects of high effluent concentrations of suspended particulates on the growth and condition of oysters and macroalgae. The results demonstrated that high concentrations of particulates inhibited growth and reduced the condition of oysters and macroalgae. Allowing the effluent to settle before biofiltration improved growth and reduced signs of stress in the oysters and macroalgae. A settling time of 6 h reduced particulates to a level that prevented fouling of the oysters and macroalgae.     

The disappearance of oysters from the Wadden Sea: a cautionary tale for no‐take zones

• 1. The question as to whether no‐take zones, as reference areas in the Wadden Sea (eastern North Sea), may develop within a few years or decades towards an ecological situation similar to the one which may have existed in earlier times is examined.
• 2. It is argued that the driving forces behind changes in species and habitats in the Wadden Sea are natural long‐term variability of abiotic factors and area‐wide anthropogenic impact (coastal engineering). 3. Fisheries in the Wadden Sea are shown to be of minor importance, and it is proposed that establishment of no‐take zones here will not result in the recovery and recolonization of missing species and habitats. The examples of species include European oysters (Ostrea edulis), sabellarian reefs (Sabellaria spinulosa) and white weed (Sertularia cupressina, Hydrallmania falcata).

Copyright © 2004 John Wiley & Sons, Ltd.     

Changes in the distribution of epifaunal reefs and oysters during 130 years of dredging for oysters in Foveaux Strait,southern New Zealand

1. Foveaux Strait, a narrow seaway that is exposed to heavy wave action and strong tidal currents, has been the subject of an oyster fishery for over 130 years. Before the oyster fishery commenced the seafloor was extensively covered by epifaunal reefs that were tidally‐oriented, linear aggregations of patch reefs. 2. Patch reefs are formed by the bryozoan Cinctipora elegans cemented by encrusting bryozoa, ascidians, sponges, and polychaetes. The molluscan epifauna is dominated by the oyster, Tiostrea chilensis and bysally attached bivalves. Mortality of oysters is probably lower and recruitment and growth may be higher within the reef habitat. 3. Fishers found commercial densities of oysters occurred only on epifaunal reefs. Fishers exploited local groups of reefs. These groups form the patchily distributed oyster beds characteristic of this fishery. 4. Dredging for oysters progressively modified reefs until oysters were the only epifauna remaining. Dredges caught oysters more efficiently after the catch bag no longer became saturated with other epifauna. This heightened efficiency allowed fishers to rapidly reduce oyster density to commercial extinction. Oyster density has not rebuilt on oyster beds abandoned by fishers. 5. The rate of modification of epifaunal reefs was slower during the early years of the fishery but has accelerated, especially over the last 37 years. Frequency of disturbance increased as the numbers of vessels fishing grew and fishers developed speedier dredging methods. Intensity of disturbance also increased as heavier dredges were introduced and allowed focused fishing of reefs. 6. Oysters became reduced to low densities in the eastern and central areas that fishers then abandoned. The commercially exploited area subsequently expanded to the limits of Foveaux Strait. 7. With accelerated modification of oyster habitat, disease mortality has become more important. 8. Attempting to rebuild the fishery by oyster enhancement may be more successful conjoined with habitat restoration. Copyright © 1999 John Wiley & Sons, Ltd.     

The increased efficiency of fish swimming in a school

There is increasing evidence that fish gain energetic benefits from the hydrodynamic interactions when they swim in a school. The most recent indications of such benefits are a lower tail (or fin) beat at the back of a school and reduced oxygen consumption in schooling fish versus solitary ones. How such advantages may arise is poorly understood. Current hydrodynamic theories concern either fish swimming side by side or in a diamond configuration and they largely ignore effects of viscosity and interactions among wakes and individuals. In reality, however, hydrodynamic effects are complex and fish swim in many configurations. Since these hydrodynamic effects are difficult to study empirically, we investigate them in a computer model by incorporating viscosity and interactions among wakes and with individuals. We compare swimming efficiency of model fish (based on shapes of mullets of 126 mm) travelling solitarily and in schools at several interindividual distances in four different configurations (diamond, rectangular, phalanx and line). We show that these fish always swim more efficiently in a school than alone (except in a dense phalanx). We indicate how this efficiency may emerge from several kinds of interactions between wakes and individuals. As individuals in our simulations are not even intending to exploit the wake, gains in efficiency are obtained more easily than previously thought.     

中国牡蛎分类方法研究进展

牡蛎(Oyster)为世界性广布种,是我国重要的海水养殖对象.由于牡蛎的贝壳随其生活环境的变化而发生极大的变化,导致了牡6的物种组成及分布问题存在很大的分歧.采用传统的形态学、解剖学等方法已不能完全解决牡蛎的分类问题.近年来,随着分子生物学技术在牡蛎分类方面的广泛应用,通过采用形态分类和分子生物学技术相结合已成为了解决...     

Asian carp farming systems: towards a typology and increased resource use efficiency

Resource use efficiency in Asian carp farming systems is analysed based on a survey of 2493 farms of nine countries. Multivariate classification of farms by intensity and diversity identified six farm types: four types of specialized aquaculture farms at different levels of intensity, and two types of integrated agriculture–aquaculture systems. Pond‐based, specialized semi‐extensive systems (using mainly inorganic fertilizers and feeds of off‐farm origin), and integrated semi‐intensive systems (using feeds and fertilizer of both on and off‐farm origin) are by far the most common types, accounting for 59% and 27% of all farms respectively. Specialized semi‐extensive systems also show the highest protein and nutrient (N and P) use efficiencies, and among the highest labour use efficiency. Super‐intensive cage farms are less efficient in nutrient and labour use, but provide very high returns to land and capital investment. On average, the aquaculture components of integrated agriculture– aquaculture systems are less nutrient, land, and labour efficient than specialized semi‐extensive systems. Integrated semi‐extensive systems (using organic fertilizers of on‐farm origin) are particularly inefficient across all indicators. Hence in practice, gains in overall resource use efficiency through on‐farm integration with agricultural production are constrained by the relative inefficiency of the aquaculture subsystems on integrated farms. Although such systems can likely be improved, integration as such is not a panacea to increasing resource use efficiency. Wide variation in resource use efficiency within all systems indicates potential for substantial efficiency gains through improved management regardless of the fundamental choice of system.     

The test of a centrifugal hematology system for use in clinical practice

The QBC is a centrifugal haematology system. Modified haematocrit capillaries are measured optically. The parameters haematocrit, total leukocyte count, relative and absolute values of granulocyte and lympho-/monocyte fractions, and total thrombocyte count are stated. The microhaematocrit method, the counting chamber, and the differential blood count are reference methods. Blood samples of the dog, cat and horse were used for the study. As a screening method the QBC analysis meets all requirements for the veterinary practice.     

The potential for Chilean oysters, Tiostrea chilensis (Philippi, 1845), from two populations in northern New Zealand as a source of larvae for aquaculture

The use of the Chilean oyster. Tiostrea chilensis (Philippi. 1845), for aquaculture has been hampered by difficulty in obtaining commercial quantities of larvae due to the low fertility of the existing broodstock of this species taken from well-known populations in Chile and the South Island of New Zealand. The larval productions of two wild populations of this oyster in northern New Zealand were assessed as potential alternative sources of broodstock for aquaculture. The study found both populations produced larvae from young, small oysters, and that a much larger proportion of the population was brooding larvae each year than has been reported elsewhere. The mean fertility of one of these populations, at 71 056 ± 3701 (SE) larvae per oyster, was the highest reported for any population of this species. The significantly higher fertility of these populations makes them well suited for further development as broodstock for aquaculture.     

Mitochondrial DNA barcoding for Okinawan oysters: a cryptic population of the Portuguese oyster Crassostrea angulata in Japanese waters

We used mitochondrial (mt) DNA barcoding to evaluate the species diversity of oysters sampled from the coast of Okinawa Island, Japan. Our analysis revealed the presence of a hitherto-unrecognized population of the Portuguese oyster Crassostrea angulata, a putative species closely related to the Pacific oyster C. gigas. Forty-eight Okinawan oyster specimens were collected and subjected to species diagnosis trials based on mtDNA barcodes. Of the 30 Crassostrea specimens, 17 were identified as C. angulata, seven as C. gigas and six as C. bilineata (syn. C. iredalei). The remaining 18 Saccostrea specimens formed several divergent clades in phylogenetic trees, although they could not be identified to species level because of the confounding taxonomy of the Saccostrea species complex. Our results stress the necessity for reviewing the species diversity of Okinawan oysters.     

Studies on triploid oysters in Australia: Evaluation of cytochalasin B and 6-dimethylaminopurine for triploidy induction in Sydney rock oysters Saccostrea commercialis (Iredale and Roughley)

Naturally spawned Sydney rock oysters Saccostrea commercialis (Iredale and Roughley),were used to determine the appropriate stage of development for inducing triploidy and to compare the effectiveness of cytochalasin B (CB) and 6-dimethylaminopurine (6-DMAP) in dose-optimization trials. Induction should commence at 50% first polar body (PB1) extrusion in eggs (approximately 17-19 min post-fertilization at 25^oC). By day 5 the highest triploidy percentage and yield (number of triploid larvae per 100 fertilized eggs) were achieved in the ranges of 0.75-1.5 mg CB 1^-1 (1.6-3.1 μm CB)or 200-400 μm 6-DMAP (32.6-65.3 mg 6-DMAP l^-1). However, CB treatment resulted in greater survival and triploidy percentage than 6-DMAP in Sydney rock oysters.     

Improving water‐use efficiency for Ictalurid catfish pond aquaculture in Northwest Mississippi,USA

We used a 50‐year (1961–2010) daily record of precipitation and evaporation in a hydrological model to simulate ground water withdrawal for the foodfish grow‐out phase of ictalurid catfish culture in northwest Mississippi, USA. The model quantified the effects of seepage, reusing water for multiple years, and managing water levels to capture rainfall (drop‐fill water management). Selecting sites with relatively impervious soils and reusing water for multiple years had large impacts on annual water use, and combining those practices with drop‐fill water management reduced simulated groundwater withdrawal to less than 60 cm year^?1 compared with more than 450 cm year^?1 for the least conservative scenario. Water conservation measures reduced estimated costs of pumping ground water from ~$1150 ha^?1 year^?1 for the least conservative set of water‐use variables to less than $110 ha^?1 year^?1 for the best set of water conservation practices. Efficiency of pumped water use was dramatically improved by intensifying production in the foodfish grow‐out phase. Combining water‐conservation practices with production intensification improved the water use index from 9.18 m³ kg^?1 for foodfish grow‐out ponds with the least conservative set of practices to 0.28 m³ kg^?1 for ponds built on soils with negligible seepage, managed with a 22.9‐cm drop/7.6‐cm fill, drained every 10 years, and producing 15 000 kg of catfish ha^?1 year^?1. When simulated ground water use for the best set of water conservation practices in foodfish grow‐out ponds was combined with estimates of ground water used for fingerling production and water used in producing grain‐based feedstuffs, total consumptive water use index for catfish culture was estimated at ~2.7 m³ kg^?1. This index is competitive with most other types of animal agriculture. Efficient water use in catfish farming is easily achieved under commercial conditions using existing simple technologies.     

Inheritance mode of microsatellite DNA markers and their use for kinship estimation in kuruma prawn Penaeus japonicus

The allelic inheritance mode of microsatellite DNA markers was examined using seven copulated wild females and their offspring. Five microsatellite loci, CSPJ002 *, CSPJ010 *, CSPJ012 *, CSPJ014 *, and CSPJ015 *, were used in the study. At almost all family/locus combinations, one sire was determined and distributions of genotypes in offspring were consistent with the Mendelian segregation ratio. Distributions of genotypes were consistent with the ratio after assuming a null allele at some loci. Consequently, the alleles of CSPJ002 * and CSPJ012 * were inherited following the Mendelian inheritance mode in every family; however, the null allele was expected in CSPJ010 *, CSPJ014 *, and CSPJ015 * in some families. Thus, these loci should be used carefully in population genetic analysis, but siblings could be detected in the dendrograms based on unweighted pair-group method using arithmetic averages (UPMGA).     

Fish population estimation: the use of rotenone to evaluate the reliability of a removal technique

Abstract. The use of a large-meshed seine net (aperture 2–5 cm) in enclosed compounds was an effective method for the capture of large grass carp, Ctenopha-ryngodon idella (Val.), and tench, Tinea tinea L., with mean fork lengths of 42–9 cm and 38–3 cm and mean weights of 1–53 kg and 1–10 kg respectively. Calculated population estimates using a constant-effort removal technique showed a high degree of accuracy for grass carp, when the absolute index of population size was checked after completion of netting with an application of a commercially available rotenone formulation. It is suggested that this was so because of the large proportion (>90%) of the total population netted. Large tench may be unsusceptible to rotenone at the low concentration of 0–5 ppm used, so no check on the accuracy of the population estimation was possible.     

The use of a geographical information system for land-based aquaculture planning

Site selection for aquaculture planning is a complex task involving the identification of areas that are economically, socially and environmentally suitable, available to aquaculture and commercially practicable. This paper reports upon a study into the use of a geographic information system (GIS) to assist in aquaculture planning. Using a case study in the site selection for land‐based shrimp farming within the Australian coastal zone, we demonstrate that a GIS has potential to assist aquaculture planning. Our analysis is based on a sequential, two‐stage approach. The first stage eliminates the grossly unsuitable portion of the study area through a preselection with low resolution, cheap and easily available data. The second stage then focuses on and ranks the remaining area using high resolution, possibly more expensive data. Finally, we use the GIS to present the results of the analysis in an easily accessible form.     

四十里湾栉孔扇贝的生长余力和C、N、P元素收支

运用生物沉积法在四十里湾养殖海区现场对栉孔扇贝 (Chlamysfarreri)的生长余力和C、N、P元素收支进行研究。结果表明 ,四十里湾不同海区生长余力SSFG差别很大。Ⅰ龄栉孔扇贝SSFG为 - 0 .74～ 2 4 .0 8J/ (ind·h) ,SSFG与饵料浓度CPOM 呈正相关关系。SSFG负值的出现主要与低饵料浓度有关。C、N、P的生长余力 (SSFG C、SSFG N、SSFG P)分别与CPOC、CPON和CPP呈正相关关系。在N的生长余力SSFG N计算中 ,如果仅考虑NH4 N排泄 ,而不考虑其他形态N的排泄 ,就可能产生相当大的偏差 ,偏差范围为 11%～ 36 % ,SSFG N越低 ,产生的偏差就越大。在饵料不足、扇贝生长受到限制的环境下计算SSFG N时 ,必须考虑其他形态N的排泄。在栉孔扇贝浅海养殖中 ,养殖密度和规模过大显然会影响扇贝本身的生长。     

Jack mackerel <Emphasis Type="Italic">Trachurus japonicus</Emphasis> juveniles use jellyfish for predator avoidance and as a prey collector

ABSTRACT:   Juveniles of carangid fishes including jack mackerel Trachurus japonicus are known to associate with jellyfishes. The function of this association behavior was studied through rearing experiments and underwater visual observations. Association behavior of jack mackerel with moon jellyfish in experimental tanks was more frequent in the presence compared to the absence of predators (chub mackerel Scomber japonicus ). In the experimental tanks, the presence of jellyfish, however, did not mitigate predation by these predators. Although jack mackerel did not feed on the jellyfish itself, they frequently fed on the captured prey ( Artemia nauplii) whilst in the gut cavity of the jellyfish. Underwater observations of giant jellyfish Nemopilema nomurai off Kyoto and Fukui prefectures revealed that approximately 30% of these jellyfish were accompanied by jack mackerel juveniles with body sizes ranging 10–45 mm standard length (SL). Considering that jack mackerel juveniles found in subtidal rocky reefs ranged 40–120 mm SL, we considered that jack mackerel from 10 to 45 mm SL associate with jellyfish as a hiding place as well as a food collector, until they find a suitable reef habitat when they attain approximately 40 mm SL.     

5种壳色长牡蛎不同组织常规营养成分分析与评价

为探究DNA甲基化在长牡蛎性腺发育中的表观遗传调控机制,对长牡蛎Htatip2的同源性、系统进化、组织表达以及三倍体性腺可育型和不育型不同发育时期的基因表达和DNA甲基化谱进行了研究。结果显示,长牡蛎Htatip2的保守结构域与美洲牡蛎的Htatip2-like的保守结构域同源性最高。qPCR分析显示, Htatip2在各个组织中均有表达,其中在雌性性腺中的表达量最高。此外,该基因的表达量在可育型三倍体牡蛎性腺中随着性腺发育成熟而升高,在不育型三倍体牡蛎性腺中表达量变化不显著。BS-PCR分析显示,该基因的甲基化水平随着性腺发育成熟而降低,与基因表达水平成负相关性。双荧光素酶报告结果显示,甲基化的Htatip2启动子片段与未甲基化的片段相比,显著抑制了荧光素酶的活性。研究表明,长牡蛎Htatip2的DNA甲基化可能通过抑制基因表达参与了性腺成熟调控。本研究为表观遗传调控机制参与牡蛎性腺发育提供了重要参考依据。