Age and growth of wild suminoe (Crassostrea ariakensis, Fugita 1913) and Pacific (C. gigas, Thunberg 1793) oysters from Laizhou Bay, China.
ABSTRACT Shell height at age estimates from Suminoe (Crassostrea ariakensis) and Pacific (C. gigas) oysters from a natural oyster reef in Laizhou Bay, China were compared with shell height at age estimates from triploid triploid /trip·loid/ (trip´loid) having triple the haploid number of chromosomes (3n).
Having three times the haploid number of chromosomes in the cell nucleus.
n. C. ariakensis of known age from the Rappahannock River Noun 1. Rappahannock River - a river that flows across eastern Virginia into the Tidewater region
Old Dominion, Old Dominion State, VA, Virginia - a state in the eastern United States; one of the original 13 colonies; one of the Confederate , Virginia. C. ariakensis and C. gigas reach shell heights in excess of 76 mm (3 inches) within 2 years after settlement regardless of the source location. This fast growth appears to continue through at least age 4 or age 5 in wild individuals, because the growth trajectories for both species had not reached asymptotic height in the oldest individuals collected. Estimates of the asymptotic maximum height (S[H.sub.max]) from fitted Von Bertalanffy (VB) growth models were greatest for Chinese C. ariakensis (244.0 mm, standard error of the mean [SE] 30.4) and near the maximum shell height (227.0 mm) measured at the time of collection. Maximum shell heights measured on live Chinese C. gigas (173.0 mm) and Rappahannock C. ariakensis (190.0 mm) were also within the standard error estimates for the S[H.sub.max] estimates from the fitted VB models for Chinese C. gigas (158.6 mm, SE 20.3) and Rappahannock C. ariakensis (183 mm, SE 19.1). Fitted VB growth curves were not significantly different between species within the same habitat, within species in different habitats or between species in different habitats. The ratio of shell height to shell width and shell height to shell inflation for triploid C. ariakensis was significantly less than similar ratios observed in wild C. ariakensis and C. gigas oysters.
KEY WORDS: Suminoe oyster, Crassostrea ariakensis, Pacific oyster Pacific oyster
An oyster (Crassostrea gigas) cultured in the United States and Europe, having a scalloped shell and a fruity flavor. Also called Portuguese oyster. , Crassostrea gigas, age determination, bivalves, oysters, growth rates Growth Rates
The compounded annualized rate of growth of a company's revenues, earnings, dividends, or other figures.
Remember, historically high growth rates don't always mean a high rate of growth looking into the future. , resilium
Bivalves carry a complete record of their lives in their shells (Pannella & MacClintock 1968, Lutz & Rhoads 1980, Richardson 2001). Environmental changes as well as seasonal changes in biology and physiology are recorded in the shell structure as external rings, internal lines and growth increments or both (e.g., Pannella & MacClintock 1968, Lutz & Rhoads 1980, Ropes 1985, Richardson 2001). Using the terminology of Richardson (2001), a growth line is an internal line deposited once a year (annually), whereas the annual growth increment is the distance separating adjacent growth lines. In oysters, internal growth lines may be observed in the resilium of the hinge structure (Richardson et al. 1993a, 1993b, Kirby et al. 1998, Richardson 2001) and in the middle homogenous homogenous - homogeneous shell layers. The resilium is protected from damage or erosion by the valves. During periods of reduced shell growth, the ligament growth also slows producing growth lines in both shell and resilium (Richardson 2001). In temperate oysters, the annual growth cycle includes one thick, grey growth line deposited in between white growth increments (Richardson et al. 1993a). Enumerating the thick grey growth lines within a resilium or shell cross section provides an estimate of age (years) for the oyster (Richardson et al. 1993a, 1993b, Kirby et al. 1998, Richardson 2001).
Pacific (Crassostrea gigas, Thunberg 1793) oysters are cultured for commercial purposes around the world with initial introductions often made to supplement native oyster stocks (see reviews by Mann 1981, Mann et al. 1991, Shatkin et al. 1997). In recent years, Suminoe (C. ariakensis, Fugita 1913) oysters have also been proposed as candidates for commercial aquaculture aquaculture, the raising and harvesting of fresh- and saltwater plants and animals. The most economically important form of aquaculture is fish farming, an industry that accounts for an ever increasing share of world fisheries production. and/ or introductions to supplement native oyster stocks (e.g., Langdon & Robinson 1996, Hallerman et al. 2002) Whereas little is known about the population age structure of wild populations of either species in natural reef settings in their native Asian waters, some data on growth rates in native waters are available. Zhang and Lou (1956, reported by Zhou & Allen 2003) report Chinese C. ariakensis reaching sizes of 100-160 mm shell height in 2-3 y, whereas Fujimori (1929, reported by Cahn 1950) describes Japanese C. ariakensis reaching 197-mm shell height at ages of 6 y; C. ariakensis from China and Japan are described as large reaching sizes in excess of 200 mm shell height (Torigoe 1981).
The observed morphology of these oysters is variable. The morphology of C. ariakensis has been described as discoid discoid /dis·coid/ (dis´koid)
2. a dental instrument with a disklike or circular blade.
3. a disk-shaped dental excavator designed to remove the carious dentin of a decayed tooth. (Ahmed 1971) and oval or rounded with relatively flat shell layers with only the left valve concave Concave
Property that a curve is below a straight line connecting two end points. If the curve falls above the straight line, it is called convex. (Wakiya 1929, Torigoe 1981). Wakiya (1929) describes shells of C. ariakensis from soft mud habitats as "extremely elongated e·lon·gate
tr. & intr.v. e·lon·gat·ed, e·lon·gat·ing, e·lon·gates
To make or grow longer.
adj. or elongated
1. Made longer; extended.
2. Having more length than width; slender. " and difficult to distinguish from C. gigas found on mud bottoms. C. gigas are also described as large (reaching shell heights >400 mm, Torigoe 1981) but both valves are concave with rippled shell layers (Torigoe 1981, Langdon & Robinson 1996). Torigoe (1981) describes C. gigas as "oval to spatulate spatulate /spat·u·late/ (spach´u-lat)
1. having a flat blunt end.
2. to mix or manipulate with a spatula.
3. ," but Wakiya (1929) describes adult C. gigas as "extremely elongated".
The objectives of this study are to describe shell morphology, shell height at age relationships and growth curves for wild C. ariakensis and C. gigas specimens collected concurrently from a natural population of reef oysters in Laizhou Bay, Gulf of Bohai, China and compare these data with shell morphology, shell height at age relationships, and growth curves for triploid C. ariakensis grown in Chesapeake Bay Chesapeake Bay, inlet of the Atlantic Ocean, c.200 mi (320 km) long, from 3 to 30 mi (4.8–48 km) wide, and 3,237 sq mi (8,384 sq km), separating the Delmarva Peninsula from mainland Maryland. and Virginia. , USA.
Oysters of both species were collected from the same natural intertidal in·ter·tid·al
Of or being the region between the high tide mark and the low tide mark.
in oyster reef in Laizhou Bay, Gulf of Bohai, China (37[degrees]14'38.0, 119[degrees]03'29.9) during a quadrat quad·rat
1. Printing A piece of type metal lower than the raised typeface, used for filling spaces and blank lines. Also called quad2.
2. survey conducted in June 2004 by Dr. Mark Luckenbach (Virginia Institute of Marine Science (VIMS VIMS Virginia Institute of Marine Science
VIMS Visible and Infrared Mapping Spectrometer
VIMS Visual Information Management System(s)
VIMS Vehicle Information Management System
VIMS Virtual Incident Management System ), Eastern Shore Laboratory) and Dr. Christopher Dr. John R. Christopher, known popularly as "Dr. Christopher" was one of very few nationally prominent doctors of herbal medicine of the middle third of the 20th century, a "dark ages" of herbalism and was responsible for the herbal renaissance of the 1960s. Richardson (University of Wales Affiliated institutions
Menai Bridge (Welsh: Porthaethwy) is a town on the island of Anglesey in Wales. ). Ambient salinities were 30 ppt ppt
1. parts per thousand
2. parts per trillion at the time of collection. Oyster shells were separated from meats in the field at the time of collection. Shells were labeled, bagged and shipped as valve pairs corresponding to individuals. The species co-occurred on the reef and were distinguished from each other by genetic analyses (mitochondrial mitochondrial
pertaining to mitochondria.
a unique set of tRNAs, mRNAs, rRNAs, transcribed from mitochondrial DNA by a mitochondrial-specific RNA polymerase, that account for about 4% of the total cell RNA that 16S-based molecular key, per Banks et al. 1993) of tissue samples conducted by Dr. Ryan Carnegie (VIMS, Department of Environmental and Aquatic Animal Health). A total of 11 C. ariakensis individuals and 186 C. gigas individuals were identified from this collection on the basis of genetic analyses.
Four triploid C. ariakensis were collected from the lower Rappahannock River, Virginia during May 2004 as the remnant of a controlled field experiment conducted with aquacultured triploid C. ariakensis in 2001 (Dr. J Noun 1. Dr. J - United States basketball forward (born in 1950)
Erving, Julius Erving, Julius Winfield Erving . Wesson, Virginia Marine Resources Commission). These animals were spawned at VIMS in June 2000 (Dr. S Dr.
dram. . K. Allen, VIMS Aquaculture Genetics and Breeding Technology Center, pers. comm.); thus when they were collected and again certified as triploid in May 2004 they were approximately 4 years old.
The hinge structure and shell morphology of each individual oyster was examined to evaluate suitability for sectioning and age estimation. Oysters in which the resilium, adductor muscle Noun 1. adductor muscle - a muscle that draws a body part toward the median line
skeletal muscle, striated muscle - a muscle that is connected at either or both ends to a bone and so move parts of the skeleton; a muscle that is characterized by scar and growth edge on the left valve that formed a straight line were deemed suitable for aging and were set aside. A total of nine Chinese C. ariakensis and 19 Chinese C. gigas were suitable for estimation of age and growth rates. All four of the Rappahannock triploid C. ariakensis were used for age estimation.
The shells for estimation of age and growth rates were gently cleaned to remove attached epifauna epifauna
Benthic animals that live on the surface of a substrate, such as rocks, pilings, marine vegetation, or the sea or lake floor itself. Epifauna may attach themselves to such surfaces or range freely over them, as by crawling or swimming. using a sonicator. Measurements of shell height (SH, maximum dimension from the hinge to the growth edge, mm), maximum shell width (SW, maximum dimension perpendicular to the hinge across one valve, mm) and maximum shell inflation (SI, maximum dimension perpendicular to the hinge across both valves, mm) were made for each individual (Fig. 1). The ratios of (1) SH to SW and (2) SH to SI were calculated for each individual as metrics to describe shell shape. SH:SW ratios near 1 indicate a disk shaped or round individual, whereas SH:SW ratio values >2 are indicative of individuals that are long and narrow. SH:SI ratios provide an index of cupping or depth. SH:SI ratio values near 1 indicate an individual that is as deep or cupped as it is long (a spherical oyster), whereas higher SH:SI values describe oysters that are longer than they are deep. SH:SW and SH:SI ratios were compared across species within a site (Chinese C. ariakensis vs. Chinese C. gigas) and across sites within a species (Chinese vs. Rappahannock C. ariakensis) using l-way ANOVAs with significance values set at P = 0.05 a priori a priori
In epistemology, knowledge that is independent of all particular experiences, as opposed to a posteriori (or empirical) knowledge, which derives from experience. .
[FIGURE 1 OMITTED]
Shells were sectioned from hinge to the growth edge along a straight line that included the resilium and adductor muscle scar (the major axis major axis
The longer of the two lines about which an ellipse is symmetrical; the axis that passes through both focuses of an ellipse.
Noun 1. of growth, Fig. 1 (a) using a diamond blade saw. Shell cross-sections were polished using wetable carborundum disks (240 through 600 grit) and diamond polishing suspension (Buehler Metadai, 6 and 1 [micro]m suspension). Shells were allowed to dry thoroughly after polishing before examination for growth signatures.
The section of the left valve containing the bulk of the adductor muscle scar was used for shell cross-section evaluation. The number of growth lines within each shell cross section were counted by following the thick grey lines that were continuous from the hinge to the outer shell layer throughout the valve radial cross section (Fig. 2a). Lines visible in the cross section had to also be visible in the resilium structure to be included (Fig. 2b). The position of growth lines along the radial cross section in relation to the resilium of the hinge ligament provides a growth curve for individual animals. The distance from the hinge to the emergence of a growth line in the shell exterior of the radial cross section was measured (mm) for each shell. The resilium was used to validate cross section lines Section lines in the United States are one mile apart. When surveyors originally map an area, for instance a township, it was their custom to divide the new township into 36 - 1 square mile sections. Property ownership often followed this layout. A section is a 1 by 1 mile area. given the foliation foliation
Planar arrangement of structural or textural features in any rock type, but particularly that resulting from the alignment of constituent mineral grains of a metamorphic rock along straight or wavy planes. and ornamentation ornamentation
In music, the addition of notes for expressive and aesthetic purposes. For example, a long note may be ornamented by repetition or by alternation with a neighboring note (“trill”); a skip to a nonadjacent note can be filled in with the intervening found in the shells of larger specimens. Shell height (mm) at age (yr) curves were plotted for populations based on the sequential measurements of growth lines (height at age) made from left valve cross sections from a size range of individuals.
[FIGURE 2 OMITTED]
Population growth curves (age (yr), shell height (mm)) were fitted using the von Bertalanffy (VB) model (von Bertalanffy 1938) with nonlinear least squares regression. This model describes maximum growth and does not assume rotational symmetry about an inflection point Inflection Point
An event that changes the way we think and act.
-Andy Grove, Founder of Intel.
For example, the fall of the Berlin Wall was an inflection point in global politics and the commercialization of the Internet was an inflection point in technology. (Brown & Rothery 1993). It has been used extensively to describe the growth of other species of shellfish (e.g., Spisula solidissima, Sephton & Bryan 1990; Rangia cuneata, Fritz et al. 1990, Mercenaria mercenaria, Jones et al. 1990, Devillers et al. 1998, Ostrea edulis, Richardson et al. 1993a and Tiostrea (=Ostrea) lutaria, Richardson et al. 1993b). The model equation is:
[MATHEMATICAL EXPRESSION A group of characters or symbols representing a quantity or an operation. See arithmetic expression. NOT REPRODUCIBLE IN ASCII ASCII or American Standard Code for Information Interchange, a set of codes used to represent letters, numbers, a few symbols, and control characters. Originally designed for teletype operations, it has found wide application in computers. .]
where S[H.sub.t] is the shell height at time t, S[H.sub.max] is the maximum or asymptotic shell height, to is the size at time 0, and k is a rate constant.
The fitted VB growth curves for populations of Chinese C. ariakensis, Chinese C. gigas, and cultured Rappahannock C. ariakensis were compared as pairs using the nonlinear coincident curve method described by Haddon (2001) based on Chen et al. (1992) and Zar (1996). This method compares two curves using the analysis of the residual sum of squares In statistics, the residual sum of squares (RSS) is the sum of squares of residuals,
In a standard regression model , where a and b to test if two or more nonlinear curves are statistically different (Haddon 2001).
RESULTS AND DISCUSSION
C.ariakensis from the Rappahannock River were more cupped than similarly sized individuals of either species from China as indicated by inflation measurements and SH:SI ratios (Table 1, Fig. 3, Fig. 4). The triploid Rappahannock River individuals were discoid (plate-like) when viewed from above as indicated by SH:SW ratios near 1 (Table 1, Fig. 3, 4). Ratios of SH:SW and SH:SI for Rappahannock C. ariakensis were significantly less than the same ratios for Chinese C. ariakensis (ANOVAs, DF = 1, F = 28.1 (SH:SW) and F = 8.86 (SH:SI), P < 0.05). Ratios of SH:SW and SH:SI from Chinese C. ariakensis and C. gigas were similar (ANOVAs, DF = 1, F = 0.73 (SH:SW) and F = 0.47 (SH:SI), P > 0.40). Ratios from all four species and site combinations satisfied assumptions of homogeneity and normality without transformation. The wild Chinese C. ariakensis and C. gigas were typically long (SH), narrow (SW), and flatter in profile (SI) with higher SH:SW and SH:SI ratios than the Rappahannock River C. ariakensis (Table 1. Fig. 3, 4). The descriptions and photographs of C. ariakensis provided by Cahn (1950) and Torigoe (1981) from Ariake Bay, Japan are similar in terms of shape (tongue-like) and SH:SW ratio to the large Chinese C. ariakensis and C. gigas examined in this study (Table 1, Fig. 3A to F,4).
[FIGURES 3-4 OMITTED]
Shell Height at Age
Chinese C. ariakensis and C. gigas displayed overlap in the range of observed shell heights at age with each other and with the triploid C. ariakensis from the Rappahannock River, Virginia (Table 2). C. ariakensis and C. gigas reach shell heights in excess of 76 mm (3 inches) within 2 years after settlement (Table 2, Fig. 5) regardless of the source location. This fast growth appears to continue through at least Age 4 (C. gigas, Fig. 5) and Age 5 (C. ariakensis, Fig. 5) in wild individuals because the growth trajectory for both species had not begun to flatten in the oldest individuals collected (Fig. 5). The observed shell height ranges for each age class (Table 2) are within the ranges of previously published reports of shell heights at age for both species (Table 3). The triploid C.ariakensis in the Rappahannock River 2001 to 2004 followed a growth trajectory similar to that reported for Ariake Bay Japan by Cahn (1950, from Fujimori 1929, Fig. 5). The Rappahannock animals had not reached asymptotic shell height when they were collected in May 2004 (Fig. 5).
[FIGURE 5 OMITTED]
The observed range in shell heights at Age 1 for the Chinese oysters may be the result of differences in the timing of individual recruitment. Potential differences in the timing of spawning (Perdue Perdue may refer to:
VB Growth Model Coefficients and Model Fitting
Fitted VB growth curves (Fig. 6) were not significantly different between species within the same habitat (Chinese C. gigas vs. C. ariakensis, F = 2.2, P = 0.10, degrees of freedom = 71), within species in different habitats (Chinese C. ariakensis vs. Rappahannock C. ariakensis, F = 1.13, P = 0.35, df = 45) or between species in different habitats (Chinese C. gigas vs. Rappahannock C. ariakensis, F = 0.93, P = 0.43, df = 55).
[FIGURE 6 OMITTED]
Estimates of the asymptotic maximum height (S[H.sub.max]) were greatest for Chinese C. ariakensis (244.0 mm, SE 30.41) and near the maximum shell height (227.0 mm) measured at the time of collection (Fig. 6, Table 4). Maximum shell heights measured on live Chinese C. gigas (173.0 mm) and Rappahannock C. ariakensis (190.0 mm) were also within the standard error estimates for the S[H.sub.max] estimates from the fitted VB models for Chinese C. gigas (158.6 mm, SE 20.25) and Rappahannock C. ariakensis (183 mm, SE 19.14; Table 4). The reported S[H.sub.max] estimates for C. ariakensis (Table 4) are within the range of shell heights reported for C. ariakensis from Ariake Bay, Japan (Cahn 1950:240 mm; Torigoe 1981:200 mm). The S[H.sub.max] estimates for C. gigas (Table 4) are smaller than the reported maximum size range for Japan (Cahn 1950: Tokoro, 400 mm; Torigoe 1981: Ariake Bay, 448 mm). The lack of representation of older age classes in the wild population and the fact that 13 out of the 19 C. gigas examined were 2 years old or less with only one 4 year old available resulted in disproportionate representation of younger individuals and uneven sample sizes across the age distribution, which may have skewed skewed
curve of a usually unimodal distribution with one tail drawn out more than the other and the median will lie above or below the mean.
skewed Epidemiology adjective Referring to an asymmetrical distribution of a population or of data the estimate of asymptotic height towards the smaller individuals (Fig. 5 and 6, Tables 2 and 4).
The k model parameter specifies the curvature of the fitted growth line (Gallucci & Quinn 1979) and is associated with the rate at which the organism approaches maximum size (Gallucci & Quinn 1979). Observed k values (Table 4) for C. ariakensis were 0.33 (Chinese, diploid diploid /dip·loid/ (dip´loid)
1. having two sets of chromosomes, as normally found in the somatic cells; in humans, the diploid number is 46.
2. an individual or cell having two full sets of homologous chromosomes. ) and 0.55 (Rappahannock triploid), respectively with a k value of 0.68 observed for the C. gigas. Coefficients of determination (R2) for the Chinese and Rappahannock C. ariakensis were greater than or equal to 0.94 (Table 4). The C. gigas coefficient of determination Coefficient of determination
A measure of the goodness of fit of the relationship between the dependent and independent variables in a regression analysis; for instance, the percentage of variation in the return of an asset explained by the market portfolio return. Also known as R-square. was 0.89 and this may be reflective of the fact that most of the specimens examined (17/19) were less than 3 y old (Fig. 5, Tables 2 and 4). The relative under representation or absence of older C. gigas at or near asymptotic height is reflected in the high k value (0.68) and lower coefficient of determination (0.89) relative to the C. ariakensis populations both of which had more balanced distribution of individuals across age classes (Fig. 5, Tables 2 and 4).
Salinities in Laizhou Bay (30 ppt) are higher than those typically observed in the Lower Rappahannock River (12-15 ppt, Stroup & Lynn 1963), but both sites have salinities within the documented salinity tolerance of both species (e.g., Robinson 1992, Langdon & Robinson 1996, Almeida et al. 1997, Calvo et al. 1999, 2001, Grabowski et al. 2004). Seasonally water temperatures in the Rappahannock River range from 4[degrees]C to 28[degrees]C (Stroup & Lynn 1963). Laizhou Bay probably experiences a similar annual water temperature range based on documented annual water temperature profiles from adjacent habitats (Yellow Sea, Chung et al. 1993; South Korean coastal habitats, Kang et al. 2000).
Oysters have the potential to live in excess of 10 y in the absence of disease pressure, environmental degradation Environmental degradation is the deterioration of the environment through depletion of resources such as air, water and soil; the destruction of ecosystems and the extinction of wildlife. or human fishing pressure (Richardson et al. 1993a, 1993b). Evolutionarily life history has evolved to ensure success of the species over the course of its lifetime; that is, each individual only has to reproduce successfully once to maintain the population. Recruitment in wild populations should not necessarily be expected every year given the potential for interannual variability in recruitment to estuarine es·tu·a·rine
1. Of, relating to, or found in an estuary.
2. Geology Formed or deposited in an estuary.
Adj. 1. estuarine - of or relating to or found in estuaries
estuarial and marine benthic ben·thos
1. The collection of organisms living on or in sea or lake bottoms.
2. The bottom of a sea or lake.
[Greek. habitats (Loosanoff 1966, Powell & Cummins 1985). The observed age distribution within wild collections (11 2-y-old C. gigas out of 19 total, four 5-y-old C. ariakensis out of 9 total) indicates that we are seeing cohorts. Size variation within a cohort may reflect time of settlement (early vs. late, see earlier), position in reef structure, or local conditions in the microhabitat microhabitat
the normal environment, the natural home, of a microorganism. in which the animal settled.
Comparisons of shell height at age and fitted growth curves present one element of comparison between oyster species within and across sites but these comparisons do not address the difference in inflation rates/cupping observed between the Rappahannock triploid C. ariakensis and the wild oysters of both species. The discoid, cupped Rappahannock oysters were larger in all dimensions than the Chinese oysters. When the four triploid Rappahannock C. ariakensis were shucked in May 2004, the meat fully filled the shell cavity with an average meat wet weight of 117.5 g (standard error of the mean, SE = 7.43 g) and average dry weight of 27.01 g (SE = 2.24 g), J. Harding, unpublished data). This effective increase in shell volume has a direct correlation Noun 1. direct correlation - a correlation in which large values of one variable are associated with large values of the other and small with small; the correlation coefficient is between 0 and +1
positive correlation to the biomass of the animal and, in diploid individuals, fecundity fecundity /fe·cun·di·ty/ (fe-kun´dit-e)
1. in demography, the physiological ability to reproduce, as opposed to fertility.
2. ability to produce offspring rapidly and in large numbers. . In the absence of tissue weights (wet or dry) for the diploid Chinese oysters, direct comparisons of biomass within a species (triploid vs. dipoloid), site (C. ariakensis versus C. gigas) or within species across sites are impossible, although it is probable that biomass trends for sites and species follow the observed trends in external morphology. In the absence of detailed habitat or ecological information for either collection site (e.g., annual temperature and salinity profiles, sediment characterization, population density) it is impossible to attribute observed differences in morphology to genetic (triploid vs. diploid), habitat, or ecological factors including competition for space or resources. Application of these growth trajectories to other oyster populations and habitats must include consideration of genetics and individual morphology (biomass) as well as ambient seasonal salinity and water temperature profiles for the habitats of interest.
The authors thank Mr. Kirby A. Carpenter (Potomac River Potomac River
River, east-central U.S. Rising in the Appalachian Mountains of West Virginia, it is about 287 mi (462 km) long. It flows southeast through the District of Columbia into Chesapeake Bay. It is navigable by large vessels to Washington, D.C. Fisheries Commission) for his interest in and support of the project. Drs. Mark Luckenbach (VLMS VLMS Visceral Larva Migrans Syndrome ESL (1) An earlier family of client/server development tools for Windows and OS/2 from Ardent Software (formerly VMARK). It was originally developed by Easel Corporation, which was acquired by VMARK. ) and Christopher Richardson (University of Wales-Bangor, Menai Bridge) collected the Chinese oysters in June 2004. Dr. Ryan Carnegie (VIMS EAAH) provided genetic identification of individual Chinese oysters. Dr. James Wesson (Virginia Marine Resources Commission) and Dr. Standish K. Allen, Jr. (VLMS ABC ABC
in full American Broadcasting Co.
Major U.S. television network. It began when the expanding national radio network NBC split into the separate Red and Blue networks in 1928. ) made the triploid Rappahannock individuals available. Ms. Karen Hudson (VIMS ABC) and Dr. Allen provided access to original literature used in Zhou and Allen (2003). Dr. Allen and Ms. Melissa Southworth (VIMS Molluscan mol·lus·can also mol·lus·kan
Of or relating to the mollusks.
A mollusk. Ecology Program) provided helpful reviews of earlier versions of this manuscript. This is Contribution Number 2725 from the Virginia Institute of Marine Science. Funding for this project was provided by Potomac River Fisheries Commission and Maryland Department of Natural Resources The Maryland Department of Natural Resources is a Government agency in the state of Maryland charged with maintaining natural resources such as state parks, public lands, state forests, and recreation areas. .
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The structure of an organism or object as revealed through microscopic examination.
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JULIANA M. HARDING * AND ROGER MANN
Department of Fisheries Science, Virginia Institute of Marine Science, College of William and Mary Noun 1. William and Mary - joint monarchs of England; William III and Mary II , P.O. Box 1346, Gloucester Point, Virginia Gloucester Point is a census-designated place (CDP) in Gloucester County, Virginia, United States. The population was 9,429 at the 2000 census. Geography
Gloucester Point is located at (37.269907, -76. 23062
* Corresponding author. E-mail: firstname.lastname@example.org
TABLE 1. Summary of morphological measurements made on individual wild diploid C. gigas and C. ariakensis from Laizhou Bay, China and cultured triploid C. ariakensis from the Rappahannock River, USA. Measurements were made for shell height (SH), shell width (SW), and shell thickness or inflation (SI) as shown in Figure 1 and explained in the text. Ranges for each measurement type (SH, SW, SI) are presented for each species by habitat with average ratio and standard error of the mean (SE) values. SH Range SW Range Site Species n (mm) (mm) Laizhou Bay, China C. ariakensis 9 113-227 60-135 C. gigas 19 38-173 35-107 Rappahannock River, US C. ariakensis 4 170-190 145-157 SI Range Average SH:SW Site Species (mm) Ratio (SE) Laizhou Bay, China C. ariakensis 26.3-72.0 1.79 (0.70) C. gigas 25.0-50.0 1.92 (0.09) Rappahannock River, US C. ariakensis 55.1-79.6 1.19 (0.02) Average SH:SI Site Species Ratio (SE) Laizhou Bay, China C. ariakensis 4.01 (0.30) C. gigas 3.74 (0.23) Rappahannock River, US C. ariakensis 2.57 (0.23) TABLE 2. Observed average shell height (SH) at age (standard error of the mean) and the observed range of shell heights at age for populations of Chinese C. gigas (CHCg), Chinese C. ariakensis (CHCa), and Rappahannock C. ariakensis (RACa) examined in this study. Measurements were made from internal growth lines within the left valve of each individual. SE = standard error of the mean. Average SH Range of Observed Population Age n (mm, SE) at Age SH at Age (mm) CHCg 1 19 39.31 (2.12) 27-55 2 17 99.0 (3.78) 68-130 3 5 123.0 (6.44) 105-145 4 1 155 (NA) NA CHCa 1 9 42.7 (3.3) 27-57 2 9 101.42 (6.05) 75-134 3 6 136.83 (4.74) 120-152 4 4 167.25 (5.23) 155-179 5 4 191.25 (8.14) 170-204 RACa 1 4 43.38 (3.54) 35-50 2 4 102.37 (5.85) 95-120 3 4 136.48 (5.54) 125-150 4 4 156.20 (5.91) 140-165 NA = Not applicable. TABLE 3. Summary of published shell-heights at age for C. ariakensis and C. gigas. C. ariakensis SH Age (mm) Location 1 55 Japan (1) 45 Washington, US (1) 45-50 Oregon, US (2) 30-60 California, US (2) 2 97 Japan (1) 100 Washington, US (2) 65-90 Oregon, US (2) 110 California, US (2) 3 124 Japan (1) 4 152 Japan (1) 5 179 Japan (1) 6 197 Japan (1) C. gigas SH Age (mm) Location 1 20.1 Portuga1 (3) (SD 6.1) 24.4 Mexico (4) 30 Washington, US (2) 40-100 Oregon, US (2) 50 California, US (2) 2 60-70 Portugal (3) 65.6 Mexico (4) 110 Washington, US (2) 70-90 Oregon, US (2) 145 California, US (2) (1) Ariake Bay, Japan. Fujimori 1929 from Cahn 1950. (2) Puget Sound, Washington, US; Yasquina and Coos Bay, Oregon, US; Tomales Bay, California, US. Langdon and Robinson 1996. (3) Rio de Averio and Mondego River estuary, Portugal. Almeida et al. 1997. (4) Bahia de La Paz, Mexico. Arizpe 1996. TABLE 4. Von Bertalanffy growth model coefficients (standard error), coefficient of determination ([R.sup.2]), and mean square of residual values for populations of Chinese C. ariakensis (CHCa), Chinese C. gigas (CHCg), and Rappahannock C. ariakensis (RACa). Residual mean square values are from the linear regression of observed versus predicted shell height (see text). Population Age/n SHmax k [t.sub.0] CHCg 1/19, 2/17, 158.60 0.68 0.58 3/5,4/1 (20.25) (0.20) (0.08) CHCa 1/9,2/9, 244.00 0.33 0.40 3/6,4/4, (30.41) (0.08) (0.13) 5/4 RACa 1-4/4 183.00 0.55 0.51 (19.14) (0.15) (0.51) Residual Mean Population Age/n [R.sup.2] Square CHCg 1/19, 2/17, 0.89 383.22 3/5,4/1 CHCa 1/9,2/9, 0.94 125.33 3/6,4/4, 5/4 RACa 1-4/4 0.96 92.19