Gastropod Shell Growth Rate, Allometry, and Adult Size

1980 ◽  
pp. 379-394 ◽  
Author(s):  
Geerat J. Vermeij
Keyword(s):  
Growth Rate ◽  
Shell Growth ◽  
Adult Size ◽  
Gastropod Shell ◽  
Shell Growth Rate

Variations de la croissance de la coquille, et de la structure d'âge du bivalve Macoma balthica (L.) dans une population intertidale de l'estuaire du Saint-Laurent (Québec)

1987 ◽  
Vol 65 (8) ◽  
pp. 1906-1916 ◽  
Author(s):  
Bruno Vincent ◽  
Claude Brassard ◽  
Michel Harvey
Keyword(s):  
Growth Rate ◽  
Water Level ◽  
Shell Growth ◽  
Macoma Balthica ◽  
Annual Growth ◽  
Annual Growth Rate ◽  
Tidal Level ◽  
Lawrence Estuary ◽  
Mean Water Level ◽  
Shell Growth Rate

Greater annual shell growth rate and increased mortality are observed in Macoma balthica (L.) with an increase of immersion time in the intertidal zone of the St. Lawrence estuary. There is also a greater annual growth rate in tidal pools, and sediment temperature alone may explain spatial variations in spring and annual growth. Reciprocal transfers of specimens between upper (0.8 m above mean water level) and lower (1.2 m below mean water level) tidal level result in enhanced shell growth for individuals of the upper level transferred to the lower level. There is no corresponding change of shell growth rate for individuals of the lower level. This genotypic difference in short-term physiological responses to environmental changes may be the result of different selective pressures associated with habitat temporal heterogeneity. An opportunistic strategy is associated with the more terrestrial and unpredictable environment (upper tidal level) and a more specialized strategy accompanied by low phenotypic variability is associated with the more marine and stable environment (lower tidal level).

Isotopic partitioning between scallop shell calcite and seawater: effect of shell growth rate

2002 ◽  
Vol 66 (10) ◽  
pp. 1727-1737 ◽  
Author(s):  
Richard Owen ◽  
Hilary Kennedy ◽  
Christopher Richardson
Keyword(s):  
Growth Rate ◽  
Shell Growth ◽  
Scallop Shell ◽  
Shell Growth Rate

The influence of shell growth rate on striae deposition in the scallop Pecten maximus

2002 ◽  
Vol 82 (4) ◽  
pp. 621-623 ◽  
Author(s):  
Richard Owen ◽  
Christopher Richardson ◽  
Hilary Kennedy
Keyword(s):  
Growth Rate ◽  
Reliable Method ◽  
Seasonal Pattern ◽  
Shell Growth ◽  
Shell Height ◽  
Pecten Maximus ◽  
Growth Cycles ◽  
North Wales ◽  
Shell Growth Rate ◽  
The Relationship

The relationship between shell growth rate and striae deposition was investigated in a field study in which groups of juvenile scallops, Pecten maximus, (Pectinidae: Bivalvia) were deployed for monthly periods over a year in the Menai Strait (North Wales). The number of striae deposited per day, inter-striae width (the increment of shell deposited between successive striae) and striae abundance (the number of striae deposited per mm of shell height) all correlated well with measured shell growth rates. During the winter months, when seawater temperatures were minimal (6°C), inter-striae width declined, whilst striae abundance increased, whereas during the summer when seawater temperatures were maximal (18°C), shell growth was rapid with maximum inter-striae width, resulting in a seasonal pattern of narrowly grouped, then widely spaced striae. This seasonal pattern in inter-striae width variation provides an accurate and reliable method for estimating the number of growth cycles and hence the age of P. maximus.

Ecophenotypic plasticity in shell growth direction of asari clam Ruditapes philippinarum

2021 ◽  
pp. 1-6
Author(s):  
Takeshi Tomiyama
Keyword(s):  
Growth Rate ◽  
Shell Growth ◽  
Shell Height ◽  
Growth Direction ◽  
Ruditapes Philippinarum ◽  
Shell Morphology ◽  
Individual Growth ◽  
Shell Size ◽  
Internal Factors ◽  
Suitable Habitats

Abstract Asari clam (or Manila clam) Ruditapes philippinarum is an important bivalve for local fisheries. This species exhibits a large variation in shell morphology, and the shell roundness tends to be greater in more unsuitable habitats. To test whether the increments in shell size parameters (length, height and width) were affected solely by environmental conditions or by internal factors such as initial shell shapes or growth rate, a field caging experiment was conducted at two different sites of unsuitable and suitable habitats in Matsukawaura Lagoon, Japan, where shell shapes of wild clams were significantly different between the habitats. In the experiment, clams were released from the two sites to the same site or to the other site and were re-collected after 3, 6 and 12 months of caging. Caged clams originating from unsuitable habitats and released to suitable habitats showed a reduction in shell height relative to shell length, while clams from suitable habitats introduced to unsuitable habitats showed marked increases in both shell height and width. Generalized linear mixed models suggested that the increase in shell height was affected largely by the release habitat (environment) whereas the increase in shell width was affected largely by the individual growth rate. These results suggest that marginal growths in shell height and width respond differently to external and internal factors of clams, resulting in plasticity in their shell shapes according to the environments to which they are translocated.

The Effects of Reduced Salinity on the Shell Growth of Small Mytilus Edulis

1984 ◽  
Vol 64 (1) ◽  
pp. 171-182 ◽  
Author(s):  
Patricia C. Almada-Villela
Keyword(s):  
Growth Rate ◽  
Mytilus Edulis ◽  
High Salinity ◽  
Shell Growth ◽  
Experimental Period ◽  
Gradual Decline ◽  
Poor Growth ◽  
Term Response ◽  
Better Than

The shell growth of small coastal Mytilus edulis L. was measured at three different constant low salinities over short periods of time. Growth was significantly depressed in 6·4 and 16‰ S but not in 22·4‰ S. Fluctuating salinities between 0 and 32‰ S depressed growth whether the fluctuations were of sinusoidal or abrupt form. After 1 week of preconditioning to constant 32‰ S the growth of coastal (Bangor) mussels was better than estuarine (Conwy) mussels. However, after two weeks’ preconditioning to 32‰ S the estuarine mussels displayed the best growth. In the fluctuating regime, both coastal and estuarine mussels exhibited poor growth rates. The long-term response of the shell growth of coastal M. edulis was followed over a period of 44 days. Salinities in the range 1·8–9·6‰ S were lethal to the mussels within 10 days. In 12·8 and 16‰ S growth was initially delayed but recovered eventually. There was a gradual decline in the growth rate of the mussels exposed to the higher salinities (19·2–32‰) and an improvement in the growth of the mussels living in lower salinities (12·8 and 16‰) to levels nearly matching that of the high salinity animals by day 37. This suggests that acclimation of the shell growth of M. edulis to salinities in the 12·8–28·8‰ S range was achieved by the mussels during the experimental period.

Emission characteristics of GaInN/GaN multiple quantum shell nanowire-based LEDs with different p-GaN growth conditions

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sae Katsuro ◽  
Weifang Lu ◽  
Kazuma Ito ◽  
Nanami Nakayama ◽  
Naoki Sone ◽  
...  
Keyword(s):  
Growth Rate ◽  
Shell Growth ◽  
Light Output ◽  
High Growth ◽  
Growth Conditions ◽  
High Growth Rate ◽  
Current Injection ◽  
Emission Characteristics ◽  
Multiple Quantum ◽  
Plane Region

Abstract Improving current injection into r- and m-planes of nanowires (NWs) is essential to realizing efficient GaInN/GaN multiple quantum shell (MQS) NW-based light-emitting diodes (LEDs). Here, we present the effects of different p-GaN shell growth conditions on the emission characteristics of MQS NW-LEDs. Firstly, a comparison between cathodoluminescence (CL) and electroluminescence (EL) spectra indicates that the emission in NW-LEDs originates from the top region of the NWs. By growing thick p-GaN shells, the variable emission peak at around 600 nm and degradation of the light output of the NW-LEDs are elaborated, which is attributable to the localization of current in the c-plane region with various In-rich clusters and deep-level defects. Utilizing a high growth rate of p-GaN shell, an increased r-plane and a reduced c-plane region promote the deposition of indium tin oxide layer over the entire NW. Therefore, the current is effectively injected into both the r- and m-planes of the NW structures. Consequently, the light output and EL peak intensity of the NW-LEDs are enhanced by factors of 4.3 and 13.8, respectively, under an injection current of 100 mA. Furthermore, scanning transmission electron microscope images demonstrate the suppression of dislocations, triangular defects, and stacking faults at the apex of the p-GaN shell with a high growth rate. Therefore, localization of current injection in nonradiative recombination centers near the c-plane was also inhibited. Our results emphasize the possibility of realizing high efficacy in NW-LEDs via optimal p-GaN shell growth conditions, which is quite promising for application in the long-wavelength region.

scholarly journals The evolution of gastropod shell form: a developmental model illustrating the roles of heterochrony and non-heterochronic changes

1992 ◽  
Vol 6 ◽  
pp. 245-245
Author(s):  
Sean H. Rice
Keyword(s):  
Growth Rate ◽  
Specific Pattern ◽  
Apex Angle ◽  
Developmental Model ◽  
Gastropod Shell ◽  
Shell Form ◽  
Marine Snails ◽  
Highly Sensitive ◽  
Highly Correlated ◽  
Shell Production

The shape of an isometric gastropod shell can be described completely by specifying the pattern of shell secretion around the aperture (relative to aperture size) and the growth rate of the aperture itself. These descriptors provide a “natural” morphometric in that they correspond to the specific biological processes involved in constructing the shell.Describing shell form in this way allows us to specify what developmental changes must occur during the transition of one shell form to another. In particular, we can distinguish between transitions that can occur through purely heterochronic processes (changes in growth rate) and those that require a change in the specific pattern in which cells of the mantle lay down shell. We can also investigate just what changes occur during the ontogeny of non-isometric shells.Any change in either the pattern of shell secretion or the growth rate of the animal leads to changes in a number of classical morphometric measures, such as apex angle and whorl expansion rate. Those transformations resulting from changes in growth rate, however, are much more predictable than those resulting from changes in the pattern of shell production. A slight increase in the growth rate of the animal, for instance, produces a correspondingly slight increase in the apex angle and the rate of whorl expansion. By contrast, the consequences of a slight change in the pattern of shell production are highly sensitive to just how that change was achieved.Data from 8 genera of marine snails show that the variance within each genus, relative to the variance among all genera, is smaller for measures of aperture shape (which can only be altered through a change in the pattern of secretion of shell material) than for characters that can change through heterochronic transformations (such as apex angle). Furthermore, the shell forms of a number of non isometric shells can be described by a constant pattern of shell production and a variable growth rate.Heterochronic changes thus appear to be the preferred mechanism for changing phenotype in gastropod shells. Those characters that can only be altered by changing the pattern of shell production around the mantle, such as aperture shape, appear to be more conservative than those that can be changed through purely heterochronic transitions. This is consistent with the idea that mutations which alter many characters in a highly correlated manner have a higher probability of being favored by selection than those with relatively unpredictable consequences.

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