Oyster Crassostrea virginica Spat Settlement as it Relates to the Restoration of Fish River Reef in Mobile Bay, Alabama

Abstract.— Oyster spat settlement at four oyster reefs in Mobile Bay, Alabama, USA, was studied from August through October 1998 and May through mid November 1999. Spat collectors at the reefs were replaced every 2 wk and spat-set estimated as number of oysters per meter square per day. Water quality data at Fish River Reef was monitored using remote sensors. Spat-set data revealed significant variation between the four sites and between the 2 yr. Spat settlement was 5 to 10 times greater at the other three reefs than at Fish River Reef. Dates and intensity of oyster settlement at Fish River Reef were different from dates and intensity of oyster settlement at Shell Bank Reef, both on the eastern side of the bay. However, settlement was similar between Cedar Point Reef and White House Reef, both on the western side of the bay. Spat set appears to occur 3 wk after a rapid decline in water temperature, provided adequate oxygen concentrations are present at the time of settlement. Data collected suggest that intensity of settlement at Fish River Reef is considerably less than at other reefs in this study but could be adequate to reestablish the reef, if cultch and environmental conditions are suitable. The data also suggest that the source of larval oysters at Fish River Reef is different from the source of larval oysters at the other sites tested in the present study.     

The feasibility of oyster raft culture in east coast estuaries

Styrofoam-floated oyster rafts were used to study the feasibility of raft culture in typical American east coast estuaries. Rafts were placed in Delaware Bay and several tidal tributaries in the state of Delaware. Four types of cultch were tested for resistance to the environment and utilization by setting spat. Hatchery-spawned oysters were reared on rafts and their growth and mortality were monitored. A special raft with moveable trays was designed to study the effectiveness of air drying in controlling fouling.Rafts withstood the environmental conditions in small tidal rivers but were severely damaged by waves in Delaware Bay. Although spat set was too low for commercial purposes in the rivers, sets approaching commercial density were obtained in the bay by putting bundles of strings on the oyster beds during setting. Oysters grown on rafts reached market size in approximately 2 years in two of the rivers: slower growth was noted in the other rivers. It was shown that fouling could be controlled effectively by air drying for 4 h each week.An economic analysis of raft culture for this area was conducted at the conclusion of the study, which showed that relatively high prices would be necessary to maintain a raft-based industry at this time.     

Habitat use of globally threatened juvenile Chinese horseshoe crab,Tachypleus tridentatus under the influence of simulated intertidal oyster culture structures in Hong Kong

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健跳港上游湾区牡蛎潮间带分带格局和资源补充研究#br#

为了解牡蛎在潮间带的生态特性及资源分布情况,调查了浙江三门健跳港上游湾区牡蛎潮间带分带格局,并检验附苗器类型和地点对牡蛎资源补充的影响。结果显示:潮间带定量调查共记录到3种牡蛎,即熊本牡蛎(Crassostrea sikamea)、近江牡蛎(C.ariakensis)和香港牡蛎(C.hongkongensis),首次在浙江海域记录到香港牡蛎的自然分布。熊本牡蛎在调查的5个潮区(1.4 m、2.2 m、3.0 m、3.8m、4.6 m)均有分布,其平均密度沿增加的高程梯度呈现上升趋势,其中4.6 m潮区熊本牡蛎密度显著高于1.4 m和2.2 m潮区(P<0.05)。近江牡蛎和香港牡蛎仅分布于最底层的1.4 m和2.2 m潮区。牡蛎资源补充实验结果表明,该湾区具有很高的熊本牡蛎资源补充量,采苗地点(P<0.05)和附苗器类型(P<0.05)均显著影响牡蛎苗的密度和壳高,总体上水泥片的附苗效果要好于塑胶轮胎,上游S1点附苗效果优于下游S2点,推荐上游S1点作为熊本牡蛎附苗场。     

The Effects of Stocking Density,Bag Mesh Size,and Bottom Sediment on the Growth and Survival of the Eastern Oyster,Crassostrea virginica,with Emphasis on Controlling Oyster Spat Fouling

This study was designed to determine if oyster spat fouling upon adult oysters, Crassostrea virginica, cultured in coastal Georgia could be controlled by stocking density, bag mesh size, substrate type, and tidal level (intertidally or subtidally). Oyster gowth and survival was also monitored for each treatment. Sediment type had no effect on the number of spat per oyster either in intertidal or subtidal areas. Greater growth occurred in subtidal bags placed on sandmud and sandclay substrates. Intertidal mud and sandhnud bottom treatments showed the least growth. Survival of oysters grown intertidally (64%) was better the those cultured subtidally (27%). Mesh size of the oyster growing bags -had no effect upon oysler fouling or growth (shell length) and survival of the oysters they contained. Stocking density did affect oyster fouling, with lower fouling per oyster in higher density treatments. Density had no effect on oyster growth (shell length) or survival at the levels tested. Heavy fouling occurred on all oysters in the mesh and stocking density experiments while they were suspended off-bottom, but an I l -fold decrease in fouling occurred after bags were placed on the sublidal river bottom.     

Production of Pacific oysters, Crassostrea gigas Thunberg, from wild-caught and hatchery-produced seed grown at several densities on oyster shells

Abstract. Production of Pacific oysters was studied under pilot-scale conditions in Baynes Sound, British Columbia, using common bottom culture strategies. Four seeding treatments, each with a different seed per cultch density were cultured: wild-caught seed 5mm in shell height at 10 seed per cultch piece and hatchery produced seed 1-2 mm in shell height at densities of 11, 40 and 105 per cultch piece. The cultch material for all treatments was Pacific oyster shell. All seed was reared for approximately 1 year in a seed nursery located at the 2.2-m tidal level then transferred to a 1-m tidal level grow-out plot until harvest 4 years later in May 1988, Clusters of large numbers of oysters were separated and evenly distributed within the plots when the oysters attained a shell height of 60-100 mm. During the first year, growth was slow and mortalities were relatively high. All treatments produced oysters of similar size at harvest. The proportion surviving at harvest was substantially higher for the wild oysters which were initially larger at time of planting. Within the hatchery treatments proportional survival per cultch piece was inversely related to initial density on the shell; however, total production per cultch piece was positively related to initial density. Most efficient use of seed is attained at lower densities per shell; however, most efficient use of cultch and effort to handle cultch is attained at high densities.     

南沙群岛渚碧礁鱼类分类多样性研究

根据1999-2018年南沙群岛渚碧礁礁栖鱼类流刺网和手钓调查资料,分析了渚碧礁礁栖鱼类物种组成及分类多样性,计算了其平均分类差异指数(Δ^+)及分类差异变异指数(Λ^+)。结果显示,渚碧礁礁区共记录礁栖鱼类11目43科93属152种,其中鲈形目鱼类占绝对优势(76%);渚碧礁鱼类的Δ^+为58.75,Λ^+为102.60。与国内外其他生态系统鱼类群落组成的对比发现,渚碧礁鱼类的Δ^+高于赵述岛、米尔恩湾和圣何塞岛,低于东海陆架、南沙群岛西南陆架、北部湾和大亚湾,而Λ^+则均低于其他群岛。研究表明渚碧礁鱼类群落物种间的亲缘关系比东海陆架、南沙群岛西南陆架、北部湾和大亚湾更为接近,但比赵述岛、米尔恩湾和圣何塞岛远。物种多样性较高而分类多样性较低是渚碧礁礁栖鱼类多样性分布格局的主要特征。但该礁易受到人类活动的干扰,应及时给予保护。     

Coral communities of Biscayne Bay,Florida and adjacent offshore areas: diversity,abundance, distribution,and environmental correlates

• 1. Hardbottom habitats of Biscayne Bay, a shallow lagoon adjacent to the city of Miami, Florida, USA, contain a limited number of coral species that represent a small subset of the species found at nearby offshore hardbottom and reef habitats of the Florida Reef Tract. Although the physical characteristics of this basin make it a marginal environment for coral growth, the presence of dense populations of Siderastrea radians and Porites furcata indicate that these, as well as other corals that are found at lower densities, are able to tolerate extreme and fluctuating conditions. Three factors, temperature, sedimentation, and salinity, appear to limit coral abundance, diversity, and distribution within Biscayne Bay.
• 2. Temperatures exhibit high frequencies of extreme high and low values known to cause coral stress and mortality elsewhere. Similarly, sedimentation rates are very high and sediment resuspension caused by currents, storms and boating activities commonly bury corals under sediment layers. Sediment burial was shown experimentally to influence growth and mortality of S. radians.
• 3. The salinity of Biscayne Bay is influenced by freshwater inputs from canal, sheetflow and groundwater sources that create a near‐shore environment with low mean salinity and high salinity fluctuation. Coral communities along this western margin have the lowest coral density and species richness. Chronic exposure to low salinity was shown experimentally to cause a decrease in the growth of S. radians.
• 4. The location of Biscayne Bay, downstream of a large restoration effort planned for the Everglades watershed, highlights the need to understand the relationship between the physical environment and the health of benthic communities. The data presented here provide the type of scientific information needed so that management decisions can take into account the potential impacts of human activities on the health of coral populations that are already near their tolerance limits for temperature, salinity, and sedimentation.

Copyright © 2003 John Wiley & Sons, Ltd.     

人工鱼礁投放对莱州金城海域沉积环境地球化学要素的影响

2009年7月和2010～2011年春、夏、秋、冬4个季节共9个航次对莱州金城人工鱼礁区域和对照区域的沉积环境进行调查,并对投礁前后沉积物粒径、总氮（TN）、总磷（TP）、有机碳（TOC）和硫化物等指标的变化进行分析。结果表明,投礁后沉积物类型没有发生改变,但沉积物粒径有所增加。2009年7月,沉积物中值粒径和平均粒径均值分别为（0．156±0．084）mm和（O．157±0．076）mm,投礁后的2010年7月,沉积物中值粒径和平均粒径均值分别为（0．160±0．079）mm和（0．162±0．092mm）,且礁区沉积物中值粒径和平均粒径要高于对照区。2009～2011年7月,沉积物中其他指标变化趋势为：投礁区TN、TOc和硫化物平均含量均表现为逐年降低,TP为先升高后降低;对照区TN和TOC平均含量为先降低后升高,而TP和硫化物平均含量变化表现为逐年升高。2010年和2011年各指标的变化趋势为：礁区除TP平均含量为2011年高于2010年外,其余3项指标均为2010年高于2011年,而对照区除TOC平均含量2010年高于2011年外,其余3种指标均为2011年高于2010年;TP和硫化物平均含量为礁区高于对照区,而TN和TOC则为对照区高于礁区。     

Use of neuroactive catecholamines to chemically induce metamorphosis of hatchery-reared flat oyster, Ostrea angasi, larvae

Low numbers and unreliable wild catch of the native flat oyster, Ostrea angasi , spat has resulted in the NSW flat oyster industry being reliant on hatchery-produced spat. The need to produce culchless spat in the hatchery stimulated investigation of several catecholamines to induce metamorphosis in O. angasi larvae. Larvae were treated with one of four neuroactive catecholamines (epinephrine, epinephrine bitartrate, l -Dopa and GABA) at one of four concentrations (10⁻³, 10⁻⁴, 10⁻⁵ or 10⁻⁶  m ) for one of three treatment durations (0.5, 1–2 h) to determine morphogenic action for culchless spat production. Epinephrine bitartrate at 10⁻³ and 10⁻⁴  m and epinephrine at 10⁻³, 10⁻⁴ and 10⁻⁵  m , for a treatment duration of 1–2 h, produced significantly greater numbers of spat and culchless spat, compared with any other treatment combination. The other catecholamines tested did not induce a significant increase in the total number of spat or culchless spat, over untreated controls. Separate trials found that long-term treatment (24 h) with epinephrine bitartrate and epinephrine at morphogenic concentrations inhibited metamorphosis. Consecutive daily use of epinephrine bitartrate increased the numbers of spat and culchless spat produced, but did not affect larval or short-term post-larval survival. Treatment with 10⁻³  m epinephrine bitartrate or 10⁻⁴  m epinephrine for 1 h is recommended for routine commercial production of culchless flat oyster spat.     

Early growth and reproduction of hatchery-produced Pacific oyster Crassostrea gigas in Gamakman Bay off the southern coast of Korea

We investigated the early growth and reproduction of hatchery-produced Pacific oysters Crassostrea gigas raised in a suspended long-line facility in Gamakman Bay, off the south coast of Korea. In October 2009, 4?months after transplanting, shell length had increased from 27.4 (July) to 82.5?mm (October), and tissue weight had increased from 0.2 to 5.2?g, indicating that the oyster had reached a marketable size in this month. Histological studies indicated rapid gonad maturation, and the oysters spawned during August and October, with a peak in September. An enzyme-linked immunosorbent assay used to quantify egg biomass revealed that the oysters produced a relatively small quantity of eggs, ranging from 5.1?% (August) to 8.8?% (September) of their body weight. The low total carbohydrate reserve in the tissue recorded in August and September coincided with intense energy utilization due to spawning, while the protein maximum in September matched peak egg mass. Our results suggest that hatchery-produced seed could supply a portion of the spat required in Gamakman Bay as well as in other oyster culture grounds of Korea, where the oyster industry is facing a shortage in the supply of natural spat.     

Mortality of scallop spat in cultivation, infested with tube dwellingbristle worms, Polydora sp.

Between 1995 and 1997, a traditional Norwegian oyster poll with an attachednursery was used for the production of scallop (Pecten maximus) spat.During summer 1997, four batches of 2 mm scallop spat were placed in thenursery. In June, hydroids (Obelia) caused problems with fouling andaccumulation of sediment in the nursery. Thereafter, the scallop spat wereheavily infested with tube dwelling polychaets (Polydora sp.). Thepolychaets were both introduced with poll water and reproduced inside thenursery. Infested spat suffered high mortalities. Although the spat could have been affected by the hydroids, as well as shortage of food, Polydorainfestations were considered the main cause of the mortalities. Dead andinfested spat were continuously sorted out and discarded, but the infestationproblems persisted. As a result, the scallop spat did not represent anycommercial value for the company, and in September, the nursery wasemptied. In total, approximately one million spat – representing onethird of Norway's intensive scallop spat production in 1997, was lost.     

Growth of the native oyster Ostrea angasi using raft culture in Tasmania,Australia

Native oyster spat set on scallop shells in a hatchery showed seasonal growth and reached a mean shell length of 78.7 mm, 2 years after being suspended from a raft at North West Bay, Tasmania.Growth varied with suspension depth and to a lesser extent between ropes on the raft. Average dry weight condition index at harvest (115.6) indicated that the oysters were in very good condition although 42.7% died during the 2-year trial.     

Growth, fatness and gross biochemical composition of the Japanese oyster, Crassostrea gigas, in Stanway cylinders in the Bay of Arcachon, France

A new method of oyster cultivation, the Stanway oyster cylinder, has been investigated in the Bay of Arcachon since 1989. A comparative study was carried out between the growth of spat and 18-month-old Crassostrea gigas oysters, in cylinders and in traditional bags. The growth in height and in whole weight was lower in cylinders. In contrast, the tests showed a better quality of the meat, with higher condition index and higher carbohydrate content, and a better quality of the shell, with higher density and better shape. Therefore, because of the improvement in oyster quality, the use of the cylinder seems to be advantageous for the Arcachon oyster industry.     

牡蛎礁修复的底物筛选：新、旧牡蛎壳附苗效果比较#br#

通过2019年室内和野外附着实验,检验了牡蛎壳(新壳和旧壳)和生物膜(有生物膜和无生物膜)对牡蛎附着量的影响。室内附着实验表明,在生物膜处理下新壳上牡蛎附着量显著高于旧壳(P<0.05);而在无生物膜对照组中,新、旧壳上牡蛎附着量无显著差异(P>0.05)。野外附着实验发现,生物膜显著提升了旧壳上牡蛎附着量,但对新壳上牡蛎附着量无显著影响。通过2020年野外附着实验,检验了牡蛎壳(新壳和旧壳)和潮区(滩面以上0.6 m和1.1 m)对牡蛎和藤壶附着量的影响。牡蛎附着量在每个潮区中,15 d、45 d和70 d时新壳均显著高于旧壳(P<0.05)。藤壶附着量仅在0.6 m潮区中、15 d时新壳显著高于旧壳,而45 d和70 d时,各潮区中新、旧壳上藤壶附着量均无显著差异(P>0.05)。研究发现,总体来看新壳的附苗效果好于旧壳,这种差异涵盖了整个牡蛎繁殖、附着及补充的高峰期。因此,牡蛎礁修复中应优先选取新壳作为底物。     

A pump-pot nursery system for rearing juvenile New Zealand dredge oysters Tiostrea lutaria

A wave-operated nursery system was developed for growing hatchery-produced spat of the New Zealand dredge oyster Tiostrea lutaria (Hutton) through to a size (≈ 20 mm) suitable for on-growing in conventional oyster farming equipment. The pump-pot enabled cultch-free dredge oyster spat to be transferred from hatchery upwellers at a small size (> 2 mm), thus avoiding the need to supply them with cultured algae to maintain a high growth rate. The wave-activated pumping action of the pot maintained a sufficient flow of water through the pot to achieve rapid growth of small spat held at high densities.     

Use of quicklime to increase oyster seed production

A single application of quicklime (calcium oxide), spread at a rate of 6.75 metric tons/ha, was used to prepare dormant oyster setting beds for spat production. Of 2 000 ha in Long Island Sound, Connecticut, U.S.A., 1200 ha had sufficient shells to cover at least 75% of the bottom. However, these shells had a continuous fouling organism layer that would prevent significant oyster setting. Many beds had predator populations of sea stars (Asterias forbesi) and oyster drills (Urosalpinx cinerea and Eupleura caudata). Quicklime cleans the shells by killing fouling organisms, and also controls sea stars and embryonic oyster drills.When the supply of clean shells for annual spreading on the setting beds is limited, use of the quicklime method prepares greater quantities of shells for possible oyster set.     

When should pearl oyster,Pinctada margaritifera (L.), spat be transferred from the hatchery to the ocean?

Hatchery propagation of pearl oysters is relatively new and optimal hatchery protocols are still being developed. While in the hatchery, pearl oyster spat are supplied a constant and reliable food source and are protected from fluctuations in environmental conditions and predators. This study investigated the hypothesis that retaining blacklip pearl oyster, Pinctada margaritifera (L.), spat in the hatchery for longer periods, prior to transfer to the ocean, would improve growth and survival during early nursery culture. Results showed that the longer spat were retained in the hatchery, the smaller their average size at grading (3.5 months of age). At grading, spat transferred 3 weeks after settlement had a mean dorso–ventral shell height (DVH) of 9.2 ± 0.4 mm with 34% of individuals retained on a 10‐mm mesh. However, spat retained in the hatchery until 5, 7 and 9 weeks after settlement, had a mean DVH of 9.0 ± 0.4, 7.8 ± 0.3 and 6.3 ± 0.4 mm respectively. Only 10% of spat transferred 9 weeks after settlement were retained on a 10‐mm mesh at grading. The results probably reflect superior nutrition available in the ocean and indicate that pearl oyster spat should be transferred from the hatchery as soon as possible after settlement in order to maximize growth.     

Experimental test of oyster restoration within eelgrass

1. Both seagrasses and oysters are foundation species valued for their wide range of ecosystem services, but their space competition sets a constraint on joint benefits. A reserve for native Olympia oysters (Ostrea lurida) was established in lower Hood Canal (Washington State, USA) more than a century ago but is now devoid of that species and dominated by native eelgrass (Zostera marina). This situation sets up a conservation conflict because management activities for one species are at odds with the protection of another.
2. In experimental enhancement plots, Olympia oysters were outplanted at low density, which successfully maintained eelgrass density and production. One method was used in 2013 (seeded cultch, 8% cover) and two additional methods in 2015 (anchored cultch and single oysters, the latter at 4% cover).
3. For all outplant methods, oysters experienced 99% annual mortality, associated with the attraction of non‐native and native predators. Shell cover remained steady for a year and then declined rapidly, as shell accumulation did not exceed sedimentation rates.
4. Eelgrass per se does not preclude Olympia oysters, given that the two species were observed to co‐occur at a coastal estuarine site (Willapa Bay, Washington). However, even when socio‐political constraints on restoration activities were overcome, ecological constraints remained from predation. Competition between these two protected species was avoided, but it may be the case that top‐down control on oysters was particularly acute owing to low oyster density and/or the environmental conditions of eelgrass beds.

     

Toxicity to marine bivalves of culture supernatant fluids of the bivalve-pathogenic Vibrio strain NCMB 1338 and other marine vibrios

Abstract. Culture supernatant fluids from twelve Vibrio strains were toxic to spat of the European and Pacific oysters, Ostrea edulis L., and Crassostrea gigas L. At least three factors were present in culture supernates of one of the most virulent strains (NCMB 1338). The first was a heat-labile protein of molecular weight approximately 39000 which was lethal to oyster spat. This toxin was released during the stationary phase of culture and 72-h culture supernates contained 23·0LC₅₀ml when assayed against 2–3 mm Crassostrea gigas spat for 24 h at 20°C. Under the same assay conditions, 7-mm C. gigas spat were six times less sensitive to the toxin. The second factor was a relatively heat-stable ciliostatic toxin of molecular weight < 5000 and the third a proteinase of molecular weight 30000 which degraded gill segments of Mytilus edulis L. In addition, a haemolysin of molecular weight 20000 was produced. All these factors could be involved in the pathogenesis of 'vibriosis' in oyster larvae.