Larvae of the commercial scallop, Pecten meridionalis from Tasmania, Australia

1975 ◽  
Vol 26 (1) ◽  
pp. 109 ◽  
Author(s):  
TG Dix ◽  
MJ Sjardin
Keyword(s):  
Shell Length ◽  
Larval Shell ◽  
M 31

After fertilization in the laboratory, eggs (diameter 71 �m) of Pecten meridionalis developed to straight hinge veligers with a smallest shell length of 93 �m after 3 days at 13-15� C. The larval shell developed umbones at about 160 �m, pediveligers occurred at 180 fim and larvae began crawling at metamorphosis when the shell length was 220-240 �m 31 days after fetilization. The larval shells grew almost isometrically, and length (I) and width (w) (in �m) were described closely by the G.M. regression : w = 0.9901-18.660.

Post-Larval Development of the Tellinacean Bivalves Abra Alba, Tellina Fabula and Donax Vittatus (Mollusca: Bivalvia), With Reference to the Late Larva

1986 ◽  
Vol 66 (3) ◽  
pp. 749-762 ◽  
Author(s):  
C. M. Webb
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Larval Development ◽  
Shell Length ◽  
Larval Shell ◽  
Larval Form ◽  
Scanning Electron ◽  
Morphogenetic Change

The post-larval shell and hinge development of the bivalves Abra alba (Wood), Tellina fabula Gmelin and Donax vittatus (da Costa) from the recently metamorphosed size to a juvenile size of 1·2–1·4 mm shell length has been examined using scanning electron microscopy. Early post-larval development in the stages up to 1·0–1·2 mm size can involve considerable morphogenetic change and requires careful description with photographic developmental series. The form of the pediveliger larva is present in the early post-larval shell and confirms the identity of the larvae of A. alba and T. fabula. The veliger and pediveliger larvae of A. alba are described. The similar larval form of the tellinacean bivalves is modified by differential margin growth early in post-larval development. Comparison of these bivalves with allied species reveals that the post-larvae are distinguishable at even the smallest sizes by the shell and hinge form. The metamorphic size of A. alba ranges from 0·26 to 0·31 mm, of T. fabula from 0·25 to 0·28 mm and of D. vittatus from 0·25 to 0·35 mm. The bivalve post-larvae were collected from the shallow sublittoral of Oxwich Bay, Bristol Channel, U.K., and the larvae from the overlying waters, during the years 1980–2.

scholarly journals Adaption potential of Crassostrea gigas to ocean acidification and disease caused by Vibrio harveyi

2020 ◽  
Author(s):  
Davide Nordio ◽  
Natalie Khtikian ◽  
Sean Andrews ◽  
Daniela Bertotto ◽  
Karen Leask ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Shell Length ◽  
Crassostrea Gigas ◽  
Vibrio Harveyi ◽  
Larval Shell ◽  
Phenotypic Differences ◽  
Bivalve Larvae ◽  
Survival And Development ◽  
Estimate Heritability ◽  
Slow Growing

Abstract The survival and development of bivalve larvae is adversely impacted by ocean acidification and Vibrio infection, indicating that bivalves need to simultaneously adapt to both stressors associated with anthropogenic climate change. In this study, we use a half-dial breeding design to estimate heritability (h2) for survival to Vibrio harveyi infection and larval shell length to aragonite undersaturated and normal conditions in laboratory-reared Crassostrea gigas. Phenotypic differences were observed between families for these traits with heritability estimated to be moderate for survival to V. harveyi challenge (h2 = 0.25) and low for shell length in corrosive (Ωaragonite = 0.9, h2 = 0.15) and normal conditions (Ωaragonite = 1.6, h2 = 0.15). Predicted breeding values for larval shell length are correlated between aragonite-undersaturated and normal conditions (Spearman r = 0.63, p < 0.05), indicating that larger larvae tend to do better in corrosive seawater. Aquaculture hatcheries routinely cull slow-growing larvae to reduce and synchronize time taken for larvae to metamorphose to spat, thus inadvertently applying size-related selection for larger larvae. This indirect selection in the hatchery populations provides a plausible explanation why domesticated oyster populations are less sensitive to ocean acidification.

Larval and juvenile development of the Iceland cockle Ciliatocardium ciliatum (Fabricius, 1780) (Bivalvia: Cardiidae)

2020 ◽  
Vol 324 (2) ◽  
pp. 242-251
Author(s):  
L.P. Flyachinskaya ◽  
P.A. Lezin
Keyword(s):  
Lateral Position ◽  
Larval Shell ◽  
Subtidal Zone ◽  
Larval Stages ◽  
Posterior Shoulder ◽  
Blade Shape ◽  
The Right ◽  
Lateral Structures ◽  
Juvenile Development ◽  
Concentric Structure

The paper considers the development of Ciliatocardium ciliatum from the stage of straight hinge to juvenile. In the White Sea the spawning of C. ciliatum begins at the end of June, larvae at different stages of development occur in plankton until the end of September. The earliest of the larvae found had shell lengths of 123–130 µm. The paper first examined the anatomy and structure of the larval shell of C. ciliatum. During the development, the main stages of organogenesis were described and special attention was paid to the formation of the digestive and muscular systems. The digestive system begins to function when the larva reaches a size of 170–180 µm. The digestive gland has a two-blade shape and is shifted to the right side. The foot is formed at a size of 230 µm, the gill rudiments appear when the larva reaches 270 µm. The development of the larval shell and larval hinge of the mollusc is considered in detail. The development of the larval shell of C. ciliatum is similar to the development of other family members. Throughout all the larval stages, the shell has a rounded shape with a low umbos, and the prodissoconch II has a clearly visible concentric structure. The C. ciliatum larval hinge is characterized by weak differentiation and the absence of pronounced cardinal teeth typical for other Cardiidae. However, the lateral structures of the castle – ridges and flanges – are well developed. The ligament begins to form at a size of 240–250 µm and occupies a lateral position. The settlement of the cockle takes place in September in the subtidal zone. After the metamorphosis, a large radial sculpture is formed on the dissoconch and a number of small spikes are formed at the rib of the posterior shoulder.

The missing links: larval and post-larval development of the ascoglossan opisthobranch Elysia viridis

2000 ◽  
Vol 80 (6) ◽  
pp. 1087-1094 ◽  
Author(s):  
Cynthia D. Trowbridge
Keyword(s):  
Larval Development ◽  
Growth Rates ◽  
Shell Length ◽  
Larval Growth ◽  
Model Organism ◽  
Larval Life ◽  
Codium Fragile ◽  
Planktotrophic Larvae ◽  
Algal Diet ◽  
Better Than

The stenophagous ascoglossan (=sacoglossan) opisthobranch Elysia viridis has long been a model organism for the study of endosymbiosis or kleptoplasty as well as one of the few herbivores to consume the introduced green macroalga Codium fragile on European shores. Larval and post-larval dynamics of the ascoglossan were investigated. Planktotrophic larvae of E. viridis grew at 5–10 μm d−1 (shell length) at 15°C on a unicellular algal diet (the cryptophyte Rhodomonas baltica); larvae became competent one month post-hatching. Effective feeding and chloroplast acquisition typically started within 2–3 d of metamorphosis. Slugs grew about 8 mm in the first month of post-larval life. During this period, juveniles held in the light did not grow faster or survive better than conspecifics held in the dark; thus, functional kleptoplasty did not occur during first three weeks of benthic life. While larval growth rates and the nature of metamorphic cues are consistent with those of many other opisthobranch species with planktotrophic larvae, measures of post-larval growth—particularly as it pertains to kleptoplasty—is a new contribution to opisthobranch biology.

scholarly journals Prediction Accuracies of Genomic Selection for Nine Commercially Important Traits in the Portuguese Oyster (Crassostrea angulata) Using DArT-Seq Technology

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 210
Author(s):  
Sang V. Vu ◽  
Cedric Gondro ◽  
Ngoc T. H. Nguyen ◽  
Arthur R. Gilmour ◽  
Rick Tearle ◽  
...  
Keyword(s):  
Moisture Content ◽  
Genomic Selection ◽  
Shell Length ◽  
Prediction Accuracy ◽  
Genomic Information ◽  
Morphometric Traits ◽  
Shell Weight ◽  
Shell Width ◽  
Crassostrea Angulata ◽  
Selection For

Genomic selection has been widely used in terrestrial animals but has had limited application in aquaculture due to relatively high genotyping costs. Genomic information has an important role in improving the prediction accuracy of breeding values, especially for traits that are difficult or expensive to measure. The purposes of this study were to (i) further evaluate the use of genomic information to improve prediction accuracies of breeding values from, (ii) compare different prediction methods (BayesA, BayesCπ and GBLUP) on prediction accuracies in our field data, and (iii) investigate the effects of different SNP marker densities on prediction accuracies of traits in the Portuguese oyster (Crassostrea angulata). The traits studied are all of economic importance and included morphometric traits (shell length, shell width, shell depth, shell weight), edibility traits (tenderness, taste, moisture content), and disease traits (Polydora sp. and Marteilioides chungmuensis). A total of 18,849 single nucleotide polymorphisms were obtained from genotyping by sequencing and used to estimate genetic parameters (heritability and genetic correlation) and the prediction accuracy of genomic selection for these traits. Multi-locus mixed model analysis indicated high estimates of heritability for edibility traits; 0.44 for moisture content, 0.59 for taste, and 0.72 for tenderness. The morphometric traits, shell length, shell width, shell depth and shell weight had estimated genomic heritabilities ranging from 0.28 to 0.55. The genomic heritabilities were relatively low for the disease related traits: Polydora sp. prevalence (0.11) and M. chungmuensis (0.10). Genomic correlations between whole weight and other morphometric traits were from moderate to high and positive (0.58–0.90). However, unfavourably positive genomic correlations were observed between whole weight and the disease traits (0.35–0.37). The genomic best linear unbiased prediction method (GBLUP) showed slightly higher accuracy for the traits studied (0.240–0.794) compared with both BayesA and BayesCπ methods but these differences were not significant. In addition, there is a large potential for using low-density SNP markers for genomic selection in this population at a number of 3000 SNPs. Therefore, there is the prospect to improve morphometric, edibility and disease related traits using genomic information in this species.

SOLVING THE PUZZLE OF THE BIVALVE SHELL FRAGMENT: INFERRING THE ORIGINAL ABUNDANCE AND SIZE FREQUENCY FROM THE FRAGMENTED RECORD

Palaios ◽  
2020 ◽  
Vol 35 (10) ◽  
pp. 432-445
Author(s):  
ERIC N. POWELL
Keyword(s):  
Shell Model ◽  
Shell Length ◽  
Shell Thickness ◽  
Conservative Estimate ◽  
Potential Donor ◽  
Size Frequency ◽  
Shell Fragment ◽  
Length Width ◽  
Bivalve Shell ◽  
Original Size

ABSTRACT Much of the contribution of bivalves to paleoecology is based on the fraction preserved whole. The use of fragments has been limited by the inability to reconstruct the whole shell. For this study, shells of selected species were broken, metrics obtained for shell reconstruction, and a stepwise model developed and tested to evaluate the potential of reconstructing whole shells from fragments. The model is based on the facts that shell thickness is well correlated with shell length, width, and weight, that fragments can be assigned to shell areas, and that each shell area can be matched to a potential donor shell by combinations of length, width, and weight. Simulations using the model show that shell reconstructions are feasible and that the size frequency can be reconstructed more accurately than the number of shells. If all fragments are preserved, shell number tends to be modestly overestimated. Assuming fragment loss, the shell number estimated will be a conservative estimate of original abundance. Reconstructed size frequencies did not differ significantly from the original size frequencies of the whole shells even if 40% of the fragments were not preserved. Biovolume, consequently, may also be estimable. Standardly, bivalve fragments are enumerated by counting intact umbos. If all fragments are preserved, this approach is preferable, as shell model reconstructions overestimate abundance under that circumstance. However, the expectation that fragments with intact umbos are uniquely well preserved is unrealistic and if fragment loss has occurred, relying on all fragments may provide an improved estimate of the original abundance and, in addition, an estimate of the size frequency and the latter proves to be robust even with 40% of the fragments lost.

scholarly journals Age estimations of M 31 globular clusters from their spectral energy distributions

2006 ◽  
Vol 449 (1) ◽  
pp. 143-149 ◽  
Author(s):  
J. Ma ◽  
X. Zhou ◽  
D. Burstein ◽  
Y. Yang ◽  
Z. Fan ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
M 31
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