Showing papers in "Journal of Shellfish Research in 2008"

Settlement of Crassostrea ariakensis Larvae: Effects of Substrate, Biofilms, Sediment and Adult Chemical Cues

Abstract: The Suminoe oyster (Crassostrea ariakensis) is being considered for introduction into the Chesapeake Bay. However, our current understanding of the biology and ecology of C. ariakensis is insufficient to predict whether an introduction will be successful, provide desired benefits, or have adverse impacts. Behavior of native Eastern oyster (C. virginica) pediveligers has been studied for many years and it is well established that they use a variety of habitat characteristics when selecting a site for colonization. Perhaps the most important of these are chemical cues emitted by adult conspecifics, which can lead to gregarious larval settlement and dense, persistent reef communities. Conversely, almost nothing is known about the mechanisms that regulate larval settlement and metamorphosis for C. ariakensis or how pediveligers might respond to conditions found in Chesapeake Bay. In a comparative study with C. virginica, we examined how environmental factors such as substrate type, natural biofilms, sediment and waterborne chemical cues influence larval settlement for two C. ariakensis strains (''south China'' and ''west coast''). Our results demonstrate many similarities but also potentially important differences. Both species and strains of larvae greatly prefer natural substrates (e.g., shell) covered with biofilms for colonization but the west coast strain of C. ariakensis exhibited greater attachment onto manmade substrates (e.g., fiberglass) than C. virginica. Waterborne chemical cues emitted by adult oysters were also found to enhance substrate attachment for all larval forms but cues do not appear to be species specific. These results provide critical insight to the ability of C. ariakensis larvae to identify and colonize suitable substrates in the Chesapeake Bay, which will have a large impact on recruitment success and their ability to establish self-sustaining populations.

Long-term trends in oyster population dynamics in delaware bay: regime shifts and response to disease

Abstract: We evaluate a 54-y survey time series for the Delaware Bay oyster beds in New Jersey waters to identify the characteristics of regime shifts in oyster populations and the influence of MSX and Dermo diseases on population stability. Oyster abundance was high during the 1970s through 1985. Oyster abundance was low at the inception of the time series in 1953, remained low through 1969, and has been low since 1985 and very low since 2000. Natural mortality was low in most years prior to the appearance of MSX in 1957. From 1957 through 1966, natural mortality generally remained above 10% annually and twice exceeded 20%. Natural mortality remained well below 15% during the 1970s and into the early 1980s when oyster abundance was continuously high. The largest mortality event in the time series, an MSX epizootic that resulted in the death of 47% of the stock, occurred in 1985. Mortality rose again with the incursion of Dermo in 1990 and has remained above 15% for most years since that time and frequently has exceeded 20%. The primary impact of MSX and Dermo diseases has been to raise natural mortality and ultimately to cause a dispersed stock to retreat into its habitat of refuge in the moderately low salinity reach of the bay. The time series of oyster abundance on the New Jersey oyster beds of Delaware Bay is dominated by two regime shifts, the 1970 abundance increase that was maintained for about 15 y thereafter, and the 1985 abundance decrease that continues through today. These two regime shifts ushered in long-term periods of apparent constancy in population dynamics. The 1985 regime shift was induced by the largest MSX epizootic on record that produced high mortalities throughout a population distributed broadly throughout its habitat range after 15 y of high abundance. A putative new regime commenced circa 2000 as a consequence of a series of Dermo epizootics. Mortalities routinely exceeded 20% of the population annually during this period, with the consequence of a greater degree of stock consolidation than any previous time in the 54-y record. Extreme consolidation of the stock would appear to be a characteristic of the population's response to Dermo disease. The 1970-1984 and post-1985 regimes each were ushered in by a confluence of events unique in the 54-y time series. Each was characterized by a period of relative stability in population abundance. However, the stability in total population abundance belies a more dynamic process of stock redistribution during both time intervals, demonstrating that the appearance of constancy in stock abundance is not necessarily a result of invariant stock dynamics. Rather, the Delaware Bay oyster time series suggests that regime shifts delimit periods during which differential, often offsetting, local trends impart similar abundance levels, and thus constancy at the level of the stock masks substantive changes in local population dynamics potentially fostering future catastrophic changes in population-level attributes. Understanding such regime shifts will likely determine the success of decadal management goals more so than measures designed to influence population abundance.

Dna barcoding of lepetodrilus limpets reveals cryptic species

Abstract: Lepetodrilid limpets are common inhabitants of deep-sea hydrothermal vents worldwide, but the frequent occurrence of morphologically cryptic species makes their identification very difficult. To facilitate these identifications, we provide DNA barcodes based on ;1,000 bp of cytochrome-c-oxidase subunit I (COI), for 20 taxa within the genus Lepetodrilus. The method was also used to identify lepetodrilids that were found living on vent decapods. A preliminary phylogenetic analysis resolved relationships among members of several cryptic species complexes; however, COI sequences alone were unable to resolve higher-level systematic relationships caused by saturation of synonymous nucleotide substitutions.

Identification of Crassostrea ariakensis and Related Oysters by Multiplex Species-Specific PCR

Abstract: Genetic markers are needed for rapid and reliable identification of oysters. In this study, we developed multiplex genus- and species-specific PCR markers for the identification of oysters from China. We used the mitochondrial cytochrome oxidase I (COI) and nuclear 28S ribosomal RNA genes for marker development. DNA sequences from different species were obtained from GenBank or by direct sequencing. Sequences were aligned, and genus- and species-specific nucleotides were identified. Primers were designed for genus/species-specific amplification to generate fragments of different sizes. A multiplex set of genus- and species-specific primers from the 28S gene was able to separate C. ariakensis and C. hongkongensis from other species and assign oysters to four genera. A set of species-specific COI primers provided positive identification of all five Crassostrea species from China, C. ariakensis, C. hongkongensis, C. angulata, C. gigas, and C. sikamea in a single PCR. The multiplex PCR assays do not require fluorescence-labeling or post-PCR enzyme digestion, providing a simple, fast and reliable method for the identification of oysters from China.

Gonadal Development and Histochemistry of the Tropical Oyster, Crassostrea corteziensis (Hertlein, 1951) during an Annual Reproductive Cycle

Abstract: We describe the quantitative and qualitative histology and histochemistry for a tropical oyster, C. corteziensis sampled in a coastal lagoon in Northwest, Mexico. Males were larger than immature oysters, with females presenting intermediate values. In this species, mature organisms were found most of the year, and there were at least two strong spawning periods, one in summer and the second in autumn. The presence of mature oocytes most of the year did not allow for differentiation of an annual reproductive pattern using average oocyte diameter, as has been used in other species. There was a very short resting period in winter, particularly in December 2005, and by January to February 2006 postvitellogenic oocytes can already be found. Both sexes tended to have more lipids in the gonad tissue as maturation advanced, with an inverse correlation to carbohydrate in gonad and in vesicular tissue in females. No differences in lipids or carbohydrates content were found in digestive gland. A negative co...

Absence of cospeciation between deep-sea mytilids and their thiotrophic endosymbionts

Abstract: Molecular phylogenetic analyses revealed no evidence for cospeciation between deep-sea bathymodiolin mussels (Bivalvia: Mytilidae) and their associated thiotrophic (sulfur-oxidizing) bacterial endosymbionts. Host and symbiont tree topologies were not congruent and inferred time-depths of the gene trees were inconsistent, as expected if the mussel hosts are infected by local strains of the symbiont. Evolutionary divergence among the thiotrophs is correlated with geographical distances among sample locations. Apparently these bacteria established a global distribution long before contemporary oceanic barriers achieved their current positions, and before evolutionarily younger mussel hosts diversified into presently recognized species.

Classification of Common Oysters from North China

Abstract: Oysters are commonly found on rocky shores along China's northern coast, although there is considerable confusion as to what species they are. To determine the taxonomic status of these oysters, we collected specimens from nine locations north of the Yangtze River and conducted genetic identification using DNA sequences. Fragments from three genes, mitochondrial 16S rRNA, mitochondrial cytochrome oxidase I (COI), and nuclear 28S rRNA, were sequenced in six oysters from each of the nine sites. Phylogenetic analysis of all three gene fragments clearly demonstrated that the small oysters commonly found on intertidal rocks in north China are Crassostrea gigas (Thunberg, 1793), not C. plicatula (the zhe oyster) as widely assumed. Their small size and irregular shell characteristics are reflections of the stressful intertidal environment they live in and not reliable characters for classification. Our study confirms that the oysters from Weifang, referred to as Jinjiang oysters or C. rivularis (Gould, ...

Restoration of Oyster Reefs along a Bio-physical Gradient in Mobile Bay, Alabama

Abstract: Oyster reefs support a valuable commercial fishery based on the extraction of oysters from the biogenic reef matrix they form. This fact, combined with recent recognition of the many ecological services oyster reefs provide to estuarine ecosystems, has resulted in increased efforts to restore and/or enhance the spatial extent of oyster reefs. As part of a large-scale restoration effort in Mobile Bay, Alabama, we designed a field project to determine if the design and location across a bio-physical gradient of restored oyster reefs affect the recruitment of oysters and other sessile invertebrates. In January 2004, eight oyster reefs (625 m 2 each) were constructed in each of three areas of Mobile Bay (Cedar Point, Sand Reef, and Shellbank), which varied in water quality and spatial extent of existing oyster reefs. Four reefs were high relief ($1.0 m vertical relief) and four were low relief (0.1-0.2 m). Semiannual quadrat surveys and monthly assessments of oyster survivorship were designed to evaluate oyster recruitment, abundance, and mortality as a function of reef elevation and location. The two most abundant sessile invertebrates found in the quadrat sampling were eastern oyster (Crassostrea virginica) and recurved mussel (Ischadium recurvum). Recurved mussels were abundant on all restored reefs, but densities did not significantly vary with location or reef elevation. Oyster recruitment and abundance varied by location (Cedar Point> Sand Reef> Shellbank). Oyster recruitment was also higher on high relief reefs compared with low relief. The pattern of higher recruitment of oysters at high relief reefs suggests that in locations where oyster mortality is high (i.e., Sand Reef) or larval supply is low (i.e., Shellbank), high relief reefs are an important design element in successful reef restoration.

A Comparison of the Macrofaunal Communities Inhabiting a Crassostrea virginica Oyster Reef and Oyster Aquaculture Gear in Indian River Bay, Delaware

Abstract: The eastern oyster (Crassostrea virginica) is a vital species in the estuaries of the mid-Atlantic United States. Whereas their filtering activity and biodeposition play an important role in the ecology of these systems, the reefs they form are one of the few sources of hard bottom habitat for fouling organisms and are the foundation of a rich biological community. This species has experienced drastic declines throughout the mid-Atlantic region in the last two centuries due to overfishing, habitat loss, and disease. Much interest and effort is now focused on restoring this important commercial and ecological resource. Whereas oyster reef restoration is central to the recovery of this species and the habitat it creates, oyster aquaculture can provide many of these same services albeit on a smaller scale. This is a two-part study, assessing the macrofaunal communities associated with subtidal modified rack and bag aquaculture, conducted over the summer and fall of 2006. The first part of this study...

Interactions of Deep-Sea Vent Invertebrates with Their Environment: The Case of Rimicaris exoculata

Abstract: The vent shrimp Rimicaris exoculata thrives around many hydrothermal vent sites along the Mid-Atlantic Ridge (MAR), where it aggregates into dense swarms. In contrast to hydrothermal vent fields at the East Pacific Rise (EPR), where the biomass is dominated by tubeworms, clams, and mussels, this shrimp is one of the major animal species at MAR vents. These animals are found in the dynamic mixing interface between cold oxygenated seawater and hot, reduced hydrothermal vent fluid. The adaptation of this shrimp to the hostile deep-sea hydrothermal environment and its survival strategy has been investigated since their discovery at the TAG site in the late 1980s. Rimicaris exoculata is now known to colonize black smoker complexes along the MAR in the depth-range of 2,300-3,900 m (Rainbow, Broken Spur, TAG, Snake Pit, Logatchev, 5 S( Rimicaris cf exoculata). Although the presence of the Rimicaris genus was first believed to be restricted to the MAR, a related species, Rimicaris kairei, was found recently at the Central Indian Ridge (CIR) (Edmonds and Kairei vent field). This review summarizes the current knowledge of Rimicaris shrimp, focusing on their spatial and temporal distribution, chemical and thermal environment, as well as on possible nutrition strategies and behavioral aspects. Recent studies suggested that iron oxide encrusted bacteria hosted in the branchial chamber of R. exoculata from the Rainbow vent field (MAR) might rely on iron oxidation. Striking results on the occurrence and morphology of iron precipitates, as well as on bacterial-mineral interaction in the gill chamber, have lead to the hypothesis of an iron-based symbiosis between bacteria and the shrimp. Special attention is called to these issues.

New record of ''bathymodiolus'' mauritanicus cosel 2002 from the gulf of cadiz (ne atlantic) mud volcanoes

Abstract: The ''Bathymodiolus'' childressi group is the most geographically diverse assemblage of deep-sea mussel species. In this paper we consider several possible hypotheses to explain the present biogeographic distribution of the ''B.'' childressi species complex. Mussels were collected for the first time from mud volcanoes in the Gulf of Cadiz (NE Atlantic Ocean) during the training through research (TTR) 16 research expedition in 2006. Preliminary observations of the shell features indicate that they belong to the ''B.'' childressi species complex, which has been recognized as morphologically and genetically distinct from other Bathymodiolus species. Molecular analyses of two mitochondrial genes (COI-5 and ND4) were used to characterize the new mussel population from the Gulf of Cadiz (GOC) and to determine their phylogenetic relationships with other members of the ''B.'' childressi group. The results indicate that the GOC mussels are conspecific with ''Bathymodiolus'' mauritanicus Cosel (2002), described from West Africa margin, and support a previous hypothesis that ''B.'' mauritanicus is an amphi-Atlantic species

Analysis of the Decline of the Abalone Fishery (Haliotis fulgens and H. corrugata) along the Westcentral Coast of the Baja California Peninsula, Mexico

Abstract: We analyzed the decline in the abalone harvest of two species Haliotis fulgens and H. corrugata, from one region composed of six study zones along the Baja California peninsula, Mexico. Survey data from 1991 to 2001 were used and density estimations with a Δ-distribution were computed. The results showed a dramatic decline in density (kg/10 m2) for both species. The decline in densities of H. fulgens and H. corrugata is consistent with a pattern observed since 1975. The current condition of the abalone stock is an example of an uncontrolled fishery. An increase in fishing effort or harvest rate must be avoided because we do not know the equilibrium density of these populations.

Shell Length-at-age Relationships in James River, Virginia, Oysters (Crassostrea virginica) Collected Four Centuries Apart

Abstract: Eastern oysters were ecologically and structurally dominant features of the Chesapeake Bay prior to European colonization. Four centuries of harvest pressure, habitat degradation, and, more recently, disease activity have affected extant oyster population demographics. We compared population demographics and age-at-shell length relationships for modern mesohaline James River oyster populations with James River oysters collected in the years 1611 to 1612 by Jamestown settlers. Historic oyster collections made by hand included a more complete demographic than modern samples collected with patent tongs. Historic oysters had significantly faster growth rates than modern oyster populations. Modern oysters larger than 30–40 mm SL or age 1 grow more slowly than historic oysters of comparable ages. Unlike historic oyster populations, modern James River oyster populations are affected by Dermo and MSX. The downward trend observed in the modern age at length relationship (Fig. 4B see later) between 1 to 1....

Seasonal Variations in Reproductive Activity and Biochemical Composition of the Cockle Fulvia mutica (Reeve) from the Eastern Coast of China

Abstract: Seasonal variations in condition index and biochemical composition of the cockle Fulvia mutica (Reeve) were studied from March 2004 to February 2005 in eastern coast of China in relation to reproductive cycle. The condition index declined during gametogenesis and spawning, recovered when the gonad was in resting phase. Histological analysis and measurements of protein, glycogen and lipid levels and RNA:DNA ratio from gonad-visceral mass, mantle, adductor muscle, and foot of F. mutica were performed. Gametogenesis took place during winter and spring at the expense of reserves (glycogen in various organs, protein in the foot, lipid in the adductor muscle), which were accumulated previously during summer and autumn. Spawning occurred in May to June when water temperature was higher and food availability was abundant. The RNA:DNA ratio is a good indicator of sexual maturity in the gonad-visceral mass; the increasing RNA:DNA ratio in the gonad-visceral mass appears to show the rising synthetic activit...

Biological Characteristics of a Newly Established Green Crab (Carcinus maenas) Population in the Southern Gulf of St. Lawrence, Canada

Abstract: Various biological characteristics of the exotic green crab (Carcinus maenas) were studied in 2000 and 2001 to describe its population structure and reproductive strategy off the coast of Prince Edward Island (PEI), Canada. This particular population is found at the northern limit of the green crab distribution off the east American coast. Results showed that the number of female crabs was higher during springtime compared with the rest of the year. Male crabs were found in higher numbers from August to December. Ovigerous females were observed from early July to mid-September, their numbers peaking in early July. This was confirmed by a gonadosomatic analysis, which showed that the relative gonadal wet weight dropped from late July to mid-September 2001. Fecundity was estimated at 140,000–200,000 embryos per mass. Mating occurred after larval release, which occurred from late August to December with a peak in September. Mature males were molting from June to December, but mainly in July. This wa...

Rapid enzyme-linked immunosorbent assay for detection of the algal toxin domoic acid

Abstract: Domoic acid (DA) is a potent toxin produced by bloom-forming phytoplankton in the genus Pseudo-nitzschia, which is responsible for causing amnesic shellfish poisoning (ASP) in humans. ASP symptoms include vomiting, diarrhea, and in more severe cases confusion, loss of memory, disorientation, and even coma or death. This paper describes the development and validation of a rapid, sensitive, enzyme linked immunosorbent assay test kit for detecting DA using a monoclonal antibody. The assay gives equivalent results to those obtained using standard high performance liquid chromatography, fluorenylmethox- ycarbonyl high performance liquid chromatography, or liquid chromatography—mass spectrometry methods. It has a linear range from 0.1-3 ppb and was used successfully to measure DA in razor clams, mussels, scallops, and phytoplankton. The assay requires approximately 1.5 h to complete and has a standard 96-well format where each strip of eight wells is removable and can be stored at 4� C until needed. The first two wells of each strip serve as an internal control eliminating the need to run a standard curve. This allows as few as 3 or as many as 36 duplicate samples to be run at a time enabling real-time sample processing and limiting degradation of DA, which can occur during storage. There was minimal cross-reactivity in this assay with glutamine, glutamic acid, kainic acid, epi- or iso-DA. This accurate, rapid, cost-effective, assay offers environmental managers and public health officials an effective tool for monitoring DA concentrations in environment samples.

Physicochemical Factors of Abalone Quality: A Review

Abstract: Abalone meat has long been held in high regard for its unique sensory properties of texture and flavor, as well as its appearance. From a physicochemical viewpoint, the concentrations of certain free amino acids (especially glycine and glutamate) and the nucleotide AMP have been implicated as major factors characterizing the taste of abalone, and there seems to be a strong interaction (synergism) between them. The texture of abalone meat is related to the distribution of protein within the foot, and there is a good correlation between the collagen content and the toughness of abalone. These physicochemical factors, which largely define quality, may be influenced by species, season, diet, physiological condition and genetic factors. Protocols for handling and transport, and processing also influence quality; lactic acid is considered a useful post-mortem indicator of “freshness” in abalone meat. This review focuses on the abovementioned physicochemical factors and their link to abalone quality, an...

Taxonomic Review of the Hydrothermal Vent Shrimp Genera Rimicaris Williams & Rona and Chorocaris Martin & Hessler (Crustacea: Decapoda: Caridea: Alvinocarididae)

Abstract: A taxonomic review of the two genera of the family Alvinocarididae (Decapoda: Caridea), Rimicaris Williams and Rona, 1986 and Chorocaris Martin and Hessler 1990, is presented based on study of type materials and/or supplemental material from recent collections. Two species of Rimicaris, R. exoculata Williams and Rona 1986 and R. kairei Watabe and Hashimoto 2002, and three species of Chorocaris, C. chacei Williams and Rona 1986, C. vandoverae Martin and Hessler 1990, and C. paulexa Martin and Shank 2005, are recognized. All species are exclusively associated with deep-water hydrothermal community. Close relationship between the two genera is confirmed by morphological characters, but the monophyly of Chorocaris is not corroborated. An examination of a good series of material from the Mid-Atlantic Ridge shows that juveniles of Rimicaris exoculata can be arranged in four sequential ontogenetic stages based on morphology. A dramatic change occurs at the size of 7.0 to 9.0 mm in the carapace length. T...

Size-selectivity of the northwest atlantic sea scallop (placopecten magellanicus) dredge

Abstract: A size-selectivity curve was constructed to characterize the performance of the New Bedford style Atlantic sea scallop (Placopecten magellanicus, Gmelin 1791) dredge when it is configured to meet the requirements of Amendment #10 to the Sea Scallop Fishery Management Plan. The curve was generated using the SELECT model on catch-at-length data, obtained by simultaneously towing a New Bedford style dredge and a nonselective National Marine Fisheries Service sea scallop survey dredge from commercial scallop vessels. Data were collected during three cruises in the Northwest Atlantic between 2005 and 2006. The resultant selectivity curve yielded a 50% retention length of 100.1 mm, a selection range of 23.6 mm, and a value of 0.77 for the efficiency of the commercial dredge relative to the survey dredge. A length of 100.1 mm corresponds to a meat weight of 17.2 g in Georges Bank and 16.8 g in the mid-Atlantic. These results can assist fisheries managers with stock assessments, fishing mortality estimat...

Its length polymorphism in oysters and its use in species identification

Abstract: In an effort to develop genetic markers for oyster identification, we studied length polymorphism in internal transcribed spacers (ITS) between major ribosomal RNA genes in 12 common species of Ostreidae: Crassostrea virginica, C. rhizophorae, C. gigas, C. angulata, C. sikamea, C. ariakensis, C. hongkongensis, Saccostrea echinata, S. glomerata, Ostrea angasi, O. edulis, and O. conchaphila. We designed two pairs of primers and optimized PCR conditions for simultaneous amplification of ITS 1 and ITS2 in a single PCR. Amplification was successful in all 12 species, and PCR products were visualized on high-resolution agarose gels. ITS2 was longer than ITS 1 in all Crassostrea and Saccostrea species, whereas they were about the same size in the three Ostrea species. No intraspecific variation in ITS length was detected. Among species, the length of ITS I and ITS2 was polymorphic and provided unique identification of 8 species or species pairs: C. ariakensis, C. hongkongensis, C. sikamea, O. conchaphila, C. virginica/C. rhizophorae, C. gigas/C. angulata, S. echinata/S. glonzerata, and O. angasi/O. edulis. The ITS assay provides simple, rapid and effective identification of C. ariakensis and several other oyster species. Because the primer sequences are conserved, the ITS assay may be useful in the identification of other bivalve species.

Interrelationships between vent fluid chemistry, temperature, seismic activity, and biological community structure at a mussel-dominated, deep-sea hydrothermal vent along the east pacific rise

Abstract: In April 1991, submarine volcanic eruptions initiated the formation of numerous hydrothermal vents between 945# and 952#N along the crest of the East Pacific Rise (EPR). Dramatic changes in biological community structure and vent fluid chemistry have been documented throughout this region since the eruptive event. By April 2004, mussels (Bathymodiolus thermophilus) dominated the faunal assemblages at several of the vent sites formed during of after the 1991 eruptions, whereas other habitats within the region were dominated by the vestimentiferan Riftia pachyptila. In the present paper, we build upon the extensive data sets obtained at these sites over the past decade and describe a manipulative experiment (conducted at 949.94#N; 10414.43#W on the EPR) designed to assess interrelationships between vent fluid chemistry, temperature, biological community structure, and seismic activity. To this end, in situ voltammetric systems and thermal probes were used to measure H2S/HS - and temperature over time in a denuded region of an extensive mussel bed in which an exclusion cage was placed to inhibit the subsequent migration of mussels into the denuded area. Fluid samples were taken from the same locations to characterize the associated microbial constituents. Basalt blocks, which were placed in the cage in April 2004 and subsequently recovered in April 2005, were colonized by more than 25 different species of invertebrates, including numerous vestimentiferans and remarkably few mussels. Recorded temporal changes in vent fluid chemistry and temperature regimes, when coupled with microbiological characterization of the vent fluids and seismic activity data obtained from ocean bottom seismometers, shed considerable light on factors controlling biological community structure in these hydrothermal ecosystems.

Stable isotope variation among the mussel bathymodiolus childressi and associated heterotrophic fauna at four cold-seep communities in the gulf of mexico

Abstract: Efforts to determine the utilization of Gulf of Mexico (GOM) chemosynthetic production by benthic predators have relied on stable isotope differences between photosynthetic and chemosynthetic production. Whereas the photosynthetic δ13C value in GOM surface waters is relatively uniform, chemosynthetic production may differ in different areas depending on prevalence of thiotrophy versus methanotrophy and inorganic carbon source. In this paper we compare the δ13C and δ15N signatures of the symbiont-containing mussel, Bathymodiolus childressi Gustafson, 1998, from four different chemosynthetic sites to test the hypothesis that methanotrophic production results in significant differences among them. Bathymodiolus childressi from two areas characterized by brine seepage and biogenic methane (GC425 and GC233) had very low δ15N (−3.7‰ and −16.6‰) and δ13C (−57.5‰ and −63.5‰) relative to areas with substantial thiotrophic production (GC234 and GC185). Bathymodiolus childressi from each chemosynthetic comm...

Prospective Culture of the Cortez Oyster Crassostrea corteziensis from Northwestern Mexico: Growth, Gametogenic Activity, and Condition Index

Abstract: This study examined growth, gametogenic activity, condition index, as well as the relationship of the life cycle to environmental parameters of the Cortez oyster Crassostrea corteziensis, which was cultured for 25 mo in the lagoon of Las Guasimas (Sonora, Mexico). We used oocyte diameter and cytological characteristics of the gonad to determine reproductive stages in females and males. The condition index was used to describe the oyster's physiological health. Temperature, salinity, seston, and chlorophyll a, b, and c were recorded at the study site. The Cortez oyster had isometric shell growth, reaching 103.2 ± 1.82 mm height and 150.3 ± 4.98 g total weight. Data were adjusted to the von Bertalanffy growth equation (L∞ = 132.2 mm and K = 1.08 y−1), and survival was about 70%. This native species exhibited a distinctive gametogenic cycle, with the beginning and end of the cycle controlled by seawater temperature fluctuation (15–33°C), which once started, is continuous over a 9-mo period (March to...

Thermal Effects on Embryonic Development and Hatching for Blue King Crab Paralithodes platypus (Brandt, 1850) Held in the Laboratory, and a Method for Predicting Dates of Hatching

Abstract: Climate change may affect crab populations via thermal effects on embryo development and hatching. To test this, we measured the duration of development and hatching for the embryos of 11 blue king crabs Paralithodes platypus held at 2.3 ± 0.45, 4.3± 0.31, and 6.1± 0.61C. Embryo area, length, and width, eye length and width, and percent yolk were measured biweekly from digital images, and hatching larvae were collected daily from individual crabs. Data were compared between eggs of identical age (weeks since fertilization). Temperature did not have a significant effect on embryo measurements, but did affect development indices (percent yolk and eye size). Hatching was significantly delayed at colder temperatures with about a 46-day difference from 2.3C to 6.1C. Length of development was related to temperature via a power function, and ranged from 410 ± 8 days at 6.1 Ct o 434 ± 11 days at 2.3C. Length of hatching increased from 40 ± 4.6 days at 2.3 Ct o 55± 6.2 days at 6.1C. A model for predicting hatching dates from an eye index was developed using a quadratic equation. Embryo development at 4.3 and 6.1C was arrested between weeks 35 and 50; this evidence, plus other behavioral observations, suggests that crabs may be able to adjust development rates to partially compensate for temperature changes.

The Kumamoto Oyster Crassostrea sikamea is Neither Rare nor Threatened by Hybridization in the Northern Ariake Sea, Japan

Abstract: The status of the Kumamoto oyster Crassostrea sikamea in its native Japan is uncertain because of a lack of information about its abundance and distribution and a suggestion that C. sikamea and the Pacific oyster C. gigas hybridize in the northern Ariake Sea. Furthermore, broodstock populations on the United States Pacific coast have been hybridized with C. gigas in the past and may suffer inbreeding depression from multiple generations of hatchery-propagation. As a result, Japanese conservationists and United States oyster growers share an interest in the status of this species in the wild. We collected wild oysters from three sites in Saga Prefecture located in the northern portion of the Ariake Sea, Kyushu, Japan, in September 2006 and used molecular methods (species-specific PCR of the mitochondrial COI gene and PCR-RFLP of the nuclear ribosomal ITS1 gene) to assign 628 sampled oysters to one of three species found in this region. C. sikamea proved to be the dominant organism on artificial ha...

Chemoautotrophic Production Incorporated by Heterotrophs in Gulf of Mexico Hydrocarbon Seeps: An Examination of Mobile Benthic Predators and Seep Residents

Abstract: The continental slope of the Gulf of Mexico supports dense aggregations of tubeworms and mussels that have symbiotic chemoautotrophic bacteria Associated with these communities are numerous heterotrophic fauna and free-living bacteria Here we examine the stable C, N, and S isotope compositions of fauna from two chemoautotrophic communities to identify isotope ranges of chemoautotrophic primary production and determine the usage of that primary production by heterotrophic invertebrates The range in isotope values of the chemoautotrophic production is different between sites A brine seep (GC233) dominated by mussels symbiotic with methanotrophic bacteria has 13C and 15N depleted nutrient sources (−50 to −65‰ and −9 to −12‰, respectively), indicating methanotrophy using biogenic methane and suggesting ammonium as the dominant nitrogen source However, those same sources were 34S-enriched (6‰–11‰), as indicated by resident heterotrophs (Munidopsis sp, Methanoaricia dendrobranchiata Blake 2000, A

Cover and Colonization of Commercial Oyster (Crassostrea gigas) Shells by Fouling Organisms in San Quintin Bay, Mexico

Abstract: Fouling communities of commercial oyster crops in San Quintin Bay (Baja California, Mexico) were investigated to understand patterns of shell cover, species composition, and colonization. Historically dominated by soft sediment systems, San Quintin Bay currently supports a large oyster (Crassostrea gigas) aquaculture industry. Oyster shells are the main source of hard substratum in the bay, without which fouling communities would be mostly absent. Fouling communities are a nuisance to oyster farming because they result in increased handling time in cleaning and packaging oysters. To investigate the previously undocumented fouling communities of San Quintin, 3 sites within the bay were surveyed for 18 mo (2004 to 2005). Every month between July 2004 and December 2005 samples were deployed and collected so as to obtain shells that had been submerged for either 1, 2, 3, 6, or 12 mo. The majority of the fouling organisms were ascidians, with bryozoans, sponges, hydrozoans, and algae also present. Res...

Molluscan Shell Condition After Eight Years on the Sea Floor—Taphonomy in the Gulf of Mexico and Bahamas

Abstract: In 1993 and 1994, the shelf and slope experimental taphonomy initiative (SSETI) deployed shells of a suite of molluscan species in a range of environments of deposition (EODs) representing a range of depths, sediment types, and environmental conditions with the goal of measuring taphonomic rates over an extended period of time. In 1999 and 2001, SSETI retrieved skeletal remains from 41 locations in the Bahamas and on the Gulf of Mexico continental shelf and upper slope that had been on the seafloor for eight years. Here, we compare taphonomic processes in two different ocean basins, across 24 environments of preservation (EOP) to evaluate the influence of species, sedimentary environment, degree of burial, and water depth on the preservational process. Taphonomic signature after eight years was almost exclusively a function of location of deployment and, frequently, taphonomically-distinctive locations of deployment were subsumed within distinctive EODs. EOD-level characteristics were insufficien...

Energy Storage and Allocation During Reproduction of Pacific Winged Pearl Oyster Pteria sterna at Bahía de la Paz, Baja California Sur, Mexico

Abstract: Seasonal variations in storage, partitioning, and allocation of energy reserves (proteins, carbohydrates, lipids, and triglycerides) between germinal and somatic tissues (gonad, digestive gland, mantle tissue, and adductor muscle), were investigated related to reproduction of Pacific winged pearl oyster Pteria sterna. Tissue samples were collected every three months and analyzed with histological and biochemical techniques. Energy coefficients were also calculated with data from chemical composition of tissues. Gonad samples in almost all developmental stages occurred throughout the year, suggesting that P. sterna is a multispawning species. The evidence indicates that the main reproductive season runs from January through April (21°C to 22°C) and was identified by higher frequency of ripe gonads, more and larger postvitellogenic oocytes and higher protein, lipid, and triglyceride levels in gonad tissue. Within this study period, there were two spawning peaks, July 2003 and January 2004. Gametoge...

Hydrothermal Vent Mussel Habitat Chemistry, Pre- and Post-Eruption at 9°50′North on the East Pacific Rise

Abstract: Between October 2005 and March 2006, a seafloor volcanic eruption occurred at 950#N East Pacific Rise (EPR), establishing a ''time zero'' for characterizing newly-formed hydrothermal vent habitats and comparing them to pre-eruption habitats. Before the eruption, mussels (Bathymodiolus thermophilus) formed large aggregates between 949.6# and 950.3#N. After the eruption, the few mussels remaining were in sparsely-distributed individuals and clumps, seemingly transported via lava flows or from mass wasting of the walls of the axial trough. In situ voltammetry with solid state gold-amalgam microelectrodes was used to characterize the chemistry of vent fluids in mussel habitats from 2004 to 2007, providing data sets for comparison of oxygen, sulfide, and temperature. Posteruption fluids contained higher sulfide-to-temperature ratios (i.e., slopes of linear regressions) (10.86 mM C -1 ) compared with pre-eruption values in 2004 and 2005 (2.79 mM C -1 and -0.063 mM C -1 , respectively). These chemical differences can be attributed to the difference in geographic location in which mussels were living and physical factors arising from posteruptive fluid emissions.