scholarly journals Sex-specific growth effects in protogynous hermaphrodites

2004 ◽  
Vol 61 (3) ◽  
pp. 323-327 ◽  
Author(s):  
Philip L Munday ◽  
Alyson L Hodges ◽  
J Howard Choat ◽  
Nick Gust
Keyword(s):  
Specific Growth ◽  
Somatic Growth ◽  
Early Life History ◽  
Age Effect ◽  
Growth Effect ◽  
Otolith Growth ◽  
Precise Relationship ◽  
Size At Age ◽  
The Relationship ◽  
Slow Growing

We demonstrate sex-specific decoupling of otolith growth and somatic growth in two species of protogynous parrotfishes, Scarus frenatus and Chlorurus sordidus. Otoliths of both species increased in size consistently through life, even though somatic growth rate decreased with age (age effect). Furthermore, in S. frenatus, otoliths from terminal males were smaller than otoliths from females, despite males being larger than females of the same age. This demonstrates the presence of a sex-specific growth effect, where otoliths of fast-growing individuals (males) are smaller than otoliths of slow-growing individuals (females). The sex-specific growth effect for S. frenatus was most pronounced during the early life history, which suggests that only the fastest-growing females change sex to male. A sex-specific growth effect was also evident in C. sordidus, although it was not statistically significant because of greater variation in the otolith size of terminal males of this species. Our results demonstrate that the relationship between otolith and somatic growth can vary dramatically between the sexes. This will make it difficult to back-calculate size at age in protogynous species, or to conduct sex-specific back-calculations in gonochoristic species, unless the precise relationship between otolith and somatic growth is known for each sex.

How Reliable are Growth Back-Calculations Based on Otoliths?

1990 ◽  
Vol 47 (11) ◽  
pp. 2219-2227 ◽  
Author(s):  
Steven E. Campana
Keyword(s):  
Somatic Growth ◽  
Growth Effect ◽  
Fish Otolith ◽  
Stochastic Error ◽  
Individual Fish ◽  
Back Calculation ◽  
The Mean ◽  
The Individual ◽  
The Relationship ◽  
Slow Growing

Growth back-calculations from otoliths assume that the relationship between fish and otolith length is linear through time. The final (or observed) individual fish-otolith ratios are then combined to prepare a fish-otolith regression for the population, upon which the subsequent back-calculations are based. However, recent studies have demonstrated that the fish:otolith size ratio varies systematically with somatic growth rate, resulting in relatively large otoliths in slow-growing fish. Such a growth effect will result in a fitted fish-otolith regression which differs significantly from that of the mean of the individual fish-otolith slopes. Fraser–Lee growth back-calculations made from such a regression consistently underestimate previous lengths at age. The bias may explain the apparent ubiquity of Lee's phenomenon. Back-calculation bias was eliminated through use of an algorithm defining individual fish-otolith trajectories and a biologically determined, rather than a statistically estimated, intercept. Adaptations of the biological intercept back-calculations procedure accurately predicted previous lengths in the presence of both stochastic error and time-varying growth rates. When used to reevaluate some published back-calculations, the biological intercept procedure resulted in more accurate values than those previously estimated, and reduced or eliminated the presence of Lee's phenomenon.

Comparison of Otolith-Based Back-Calculation Methods to Determine Individual Growth Histories of Larval Striped Bass, Morone saxatilis

1992 ◽  
Vol 49 (7) ◽  
pp. 1439-1454 ◽  
Author(s):  
David H. Secor ◽  
John Mark Dean
Keyword(s):  
Striped Bass ◽  
Somatic Growth ◽  
Morone Saxatilis ◽  
Growth Effect ◽  
Individual Growth ◽  
Quadratic Model ◽  
Calculation Methods ◽  
Otolith Growth ◽  
Experimental Proof ◽  
Back Calculation

In rearing studies on 6- to 22-d-old larval striped bass, Morone saxatilis, we applied several back-calculation methods to known-growth larvae. A growth effect occurred on otolith diameter – standard length relationships, where slower growing larvae had relatively larger otoliths. Otolith growth was less affected by feeding regime than was somatic growth. Due to the conservative nature of otolith growth, proportional based (Biological Intercept Method) and simple linear regression methods linearized somatic growth transitions and did not estimate periods of negative growth. A quadratic regression method which used age as an additional predictor resulted in the accurate back-calculation of size at age in all groups of laboratory-reared larvae. However, when model coefficients were applied to a test population of pond-reared larvae, the quadratic model performed poorly. While differences in relative otolith size between pond- and laboratory-reared larvae could be ascribed to a temperature effect, the inability to apply the model also indicates a problem specific to regression-based methods. Theoretical rationale and experimental proof provided evidence for the inclusion of age in back-calculation models, but parameterization will have to occur for each field application.

scholarly journals Ocean acidification affects somatic and otolith growth relationship in fish: evidence from an in situ study

2019 ◽  
Vol 15 (2) ◽  
pp. 20180662 ◽  
Author(s):  
Antonio Di Franco ◽  
Antonio Calò ◽  
Khalil Sdiri ◽  
Carlo Cattano ◽  
Marco Milazzo ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Physiological Responses ◽  
Relative Size ◽  
Somatic Growth ◽  
Growth Effect ◽  
Otolith Growth ◽  
Coastal Fish ◽  
Somatic Growth Rate ◽  
In Situ Study

Ocean acidification (OA) may have varied effects on fish eco-physiological responses. Most OA studies have been carried out in laboratory conditions without considering the in situ p CO 2 /pH variability documented for many marine coastal ecosystems. Using a standard otolith ageing technique, we assessed how in situ ocean acidification (ambient, versus end-of-century CO 2 levels) can affect somatic and otolith growth, and their relationship in a coastal fish. Somatic and otolith growth rates of juveniles of the ocellated wrasse Symphodus ocellatus living off a Mediterranean CO 2 seep increased at the high- p CO 2 site. Also, we detected that slower-growing individuals living at ambient p CO 2 levels tend to have larger otoliths at the same somatic length (i.e. higher relative size of otoliths to fish body length) than faster-growing conspecifics living under high p CO 2 conditions, with this being attributable to the so-called ‘growth effect’. Our findings suggest the possibility of contrasting OA effects on fish fitness, with higher somatic growth rate and possibly higher survival associated with smaller relative size of otoliths that could impair fish auditory and vestibular sensitivity.

Growth and early sexual maturation in Baltic salmon (Salmo salar) parr

1992 ◽  
Vol 70 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Ingemar Berglund
Keyword(s):  
Growth Rate ◽  
Salmo Salar ◽  
Sexual Maturation ◽  
Specific Growth ◽  
Gonadal Development ◽  
Feeding Rates ◽  
Gonadal Growth ◽  
Hatchery Stock ◽  
Size At Age ◽  
The Relationship

The relationship between sexual maturation and growth in Baltic salmon (Salmo salar) parr was studied in hatchery stock originating from the Umeälven (Ume River) in northern Sweden. The probability that a male parr would mature sexually at age 1 + was positively related to its size at the start of the experiment at age 0+. The specific growth rate and condition factor of maturing and nonmaturing males were similar until the onset of gonadal growth, when the growth rate of maturing males decreased. Sibling groups of immature parr were fed different rations during the 3 weeks prior to the start of gonadal development. The incidence of sexual maturation in the groups given different rations was linearly related to the growth rate during the period of different feeding rates. This study suggests that both the size at age 1, resulting from the growth rate during the first summer, and the opportunity for growth during the period preceding the onset of gonadal growth affect the incidence of maturation in male parr of age 1 +.

Spatial Variation in Food-Limited Growth of Juvenile Greenback Flounder, Rhombosolea tapirina: Evidence from Otolith Daily Increments and Otolith Scaling

1993 ◽  
Vol 50 (12) ◽  
pp. 2558-2567 ◽  
Author(s):  
Gregory P. Jenkins ◽  
Megan Shaw ◽  
Bryce D. Stewart
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Somatic Growth ◽  
Feeding Rates ◽  
Otolith Growth ◽  
Somatic Growth Rate ◽  
Daily Increment ◽  
Daily Increments ◽  
Highly Correlated ◽  
The Relationship

Growth rates of juvenile flounder, Rhombosolea tapirina, determined from daily increment number, and the relationship between otolith and fish sizes (otolith scaling), were compared between two adjacent areas. Swan Bay, Victoria, a sheltered bay with a well-developed seagrass-detrital system, supports higher populations of prey and feeding rates of juvenile flounder than Port Phillip Bay, an area more exposed to waves and tidal currents. Temperature was significantly higher in Swan Bay (though generally less than 1 °C). Growth rates determined from daily increment number were similar within bays, but significantly different between bays. The pooled growth rate for Swan Bay (0.29 mm∙d−1) was significantly higher than for Port Phillip Bay (0.17 mm∙d−1). The same pattern was found for otolith scaling. Most of the variation in growth rates between the two bays was apparently related to food supply. A laboratory experiment indicated that otolith growth rate had a minimum level which was independent of somatic growth rate, and an additional component which was highly correlated with somatic growth rate. This resulted in an exponential decrease in otolith growth per unit somatic growth with increasing somatic growth rate such that variation in otolith scaling would be greatest at low growth rates.

Mechanoreceptor afferent activity compared with receptor field dimensions and pressure changes in feline urinary bladder

1992 ◽  
Vol 70 (11) ◽  
pp. 1457-1467 ◽  
Author(s):  
John W. Downie ◽  
J. Andrew Armour
Keyword(s):  
Contractile Activity ◽  
Bladder Wall ◽  
Afferent Activity ◽  
Intravesical Pressure ◽  
Receptor Field ◽  
Precise Relationship ◽  
Pressure Changes ◽  
The Relationship ◽  
Simple Fashion ◽  
Pressure Receptor

The relationship between vesical mechanoreceptor field dimensions and afferent nerve activity recorded in pelvic plexus nerve filaments was examined in chloralose-anesthetized cats. Orthogonal receptor field dimensions were monitored with piezoelectric ultrasonic crystals. Reflexly generated bladder contractile activity made measurements difficult, therefore data were collected from cats subjected to actual sacral rhizotomy. Afferent activity was episodic and was initiated at different pressure and receptor field dimension thresholds. Maximum afferent activity did not correlate with maximum volume or pressure. Furthermore, activity was not linearly related to intravesical pressure, receptor field dimensions, or calculated wall tension. Pressure–length hysteresis of the receptor fields occurred. The responses of identified afferent units and their associated receptor field dimensions to brief contractions elicited by the ganglion stimulant 1,1-dimethyl-4-phenylpiperazinium iodide (2.5–20 μg i.a.), studied under constant volume or constant pressure conditions, are compatible with bladder mechanoreceptors behaving as tension receptors. Because activity generated by bladder mechanoreceptors did not correlate in a simple fashion with intravesical pressure or receptor field dimensions, it is concluded that such receptors are influenced by the viscoelastic properties of the bladder wall. Furthermore, as a result of the heterogeneity of the bladder wall, receptor field tension appears to offer a more precise relationship with the activity of bladder wall mechanoreceptors than does intravesical pressure.Key words: bladder distension, intravesical pressure, sacral rhizotomy, viscoelasticity.

SENSITIVITY AND ADAPTATION OF SELECTED RHIZOBIA AND AGROBACTERIA TO PARAQUAT

1985 ◽  
Vol 65 (3) ◽  
pp. 555-562 ◽  
Author(s):  
E. B. ROSLYCKY
Keyword(s):  
Key Words ◽  
Genetic Effect ◽  
Agrobacterium Radiobacter ◽  
Plant Weight ◽  
Fast Growing ◽  
Plant Symbiont ◽  
Paraquat Resistance ◽  
Rhizobium Lupini ◽  
The Relationship ◽  
Slow Growing

Sensitivity to paraquat as function of growth varied considerably among 15 rhizobia from seven cross-inoculation groups and 13 agrobacteria from five different species. No relationship was evident between the sensitivity and the "fast-growing" or the "slow-growing" characteristics among the rhizobia. The agrobacteria were uniformly less sensitive. Maximum stabilized paraquat resistance induced by the adptations ranged from 200 μg paraquat∙mL−1 in Rhizobium lupini 112, to 20 000 μg paraquat∙mL−1 in Agrobacterium radiobacter R-590 and A. tumefaciens A6-K1. No relationship was found between the sensitivity and the adaptability. Identical lytic patterns with six bacteriophages confirmed the relationship between the adapted and parent cultures suggesting no genetic effect of paraquat on susceptibility to lysis. The bacteria-plant symbiont interaction, including nodulation, plant weight, vigor and color, was unaffected by the adaptations to paraquat resistance. Similarly, the adaptations exerted no effect on tumorigenicity of A. tumefaciens A6-K1. Key words: Rhizobia, agrobacteria, adaptation, herbicides, paraquat, N2-fixation

Depressive Disorder in Primary Care

1987 ◽  
Vol 150 (6) ◽  
pp. 737-751 ◽  
Author(s):  
C. V. R. Blacker ◽  
A. W. Clare
Keyword(s):  
Primary Care ◽  
Depressive Symptoms ◽  
Depressive Disorders ◽  
Psychiatric Morbidity ◽  
Depressive Illness ◽  
Psychiatric Disturbance ◽  
Collaborative Studies ◽  
Effect Of Treatment ◽  
Precise Relationship ◽  
The Relationship

Since the pioneering study of psychiatric morbidity in primary care by Shepherdet alin 1966, it has become increasingly apparent that a substantial proportion (between 20% and 25%) of patients consulting their GP are suffering from some form of psychiatric disturbance (Goldberg & Blackwell, 1970; Hoeperet al,1979). The composition of this psychiatric morbidity has been shown to be almost wholly affective in nature and largely mild in degree. In their important review Jenkins & Shepherd (1983) recently summarised the now extensive findings relating to overall minor psychiatric morbidity in primary care. However, recent collaborative studies between psychiatrists and GPs have identified that within this dilute pool of minor disorders, lurks a significant but poorly served population of patients suffering from depressive disorders which are by no means minor in degree. A number of crucial issues regarding this depression in primary care emerge which the present paper aims to review. In particular, how common is it, and how severe? How does it present and what, if any, are its special characteristics? What is the precise relationship between depressive symptoms and depressive illness presenting to the GP and what is the relationship between physical illness and depression? And finally, what is the course and outcome of depression in this setting and what are the indications for and effect of treatment?

FREE TRADE AND GROWTH IN THE WORLD ECONOMY

2011 ◽  
Vol 56 (03) ◽  
pp. 291-306 ◽  
Author(s):  
PETER LLOYD
Keyword(s):  
Free Trade ◽  
World Economy ◽  
Empirical Studies ◽  
Growth Effect ◽  
Limited Effect ◽  
Beneficial Effects ◽  
The World ◽  
The Relationship ◽  
Level Effect ◽  
Trade And Growth

This paper explores the relationship between free trade and the rate of economic growth. It is argued that freeing trade has both a level effect and a growth effect. Most empirical studies ignore the growth effect and, therefore, considerably understate the beneficial effects of freeing trade. Progress towards free trade in the GATT/WTO era is far from complete. Regionalism has had a limited effect on freeing trade globally. The completion of the Doha Development Round is needed to restart trade as the engine of growth.

scholarly journals Age and growth rate variation influence the functional relationship between somatic and otolith size

2017 ◽  
Vol 74 (5) ◽  
pp. 680-692 ◽  
Author(s):  
Eloïse C. Ashworth ◽  
Norman G. Hall ◽  
S. Alex Hesp ◽  
Peter G. Coulson ◽  
Ian C. Potter
Keyword(s):  
Growth Rate ◽  
Age And Growth ◽  
Growth Effect ◽  
Parameter Estimates ◽  
Rate Variation ◽  
Fish Length ◽  
Correlated Errors ◽  
Otolith Growth ◽  
Positive Dependence ◽  
Otolith Size

Curves describing the length–otolith size relationships for juveniles and adults of six fish species with widely differing biological characteristics were fitted simultaneously to fish length and otolith size at age, assuming that deviations from those curves are correlated rather than independent. The trajectories of the somatic and otolith growth curves throughout life, which reflect changing ratios of somatic to otolith growth rates, varied markedly among species and resulted in differing trends in the relationships formed between fish and otolith size. Correlations between deviations from predicted values were always positive. Dependence of length on otolith growth rate (i.e., “growth effect”) and “correlated errors in variables” introduce bias into parameter estimates obtained from regressions describing the allometric relationships between fish lengths and otolith sizes. The approach taken in this study to describe somatic and otolith growth accounted for both of these effects and that of age to produce more reliable determinations of the length–otolith size relationships used for back-calculation and assumed when drawing inferences from sclerochronological studies.

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