Variations in the contribution of transport to changes in planktonic animal abundance: a study of the flux of fish larvae in Conception Bay, Newfoundland

1995 ◽  
Vol 52 (7) ◽  
pp. 1475-1486 ◽  
Author(s):  
P. Pepin ◽  
J. A. Helbig ◽  
R. Laprise ◽  
E. Colbourne ◽  
T. H. Shears
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
Estimation Error ◽  
Mortality Rates ◽  
Rate Of Change ◽  
Short Term ◽  
Physical Forcing ◽  
Daily Rate ◽  
Conception Bay ◽  
And Diffusion

We investigated the magnitude of short-term variations in the flux of several species of fish larvae in Conception Bay, Newfoundland, determined the contribution of these fluxes to changes in the abundance of these species, and assessed the factors that may be causing the variations in these fluxes. The net effect of transport ranged from a daily influx of 5.8% to a daily efflux of 6.2% from the population. Short-term variations in transport were associated with variations in wind stress. The contribution of transport to variations in population abundance ranged from 12 to more than 75% of the average daily rate of change in numbers for the different species. The contribution of physical processes to estimated mortality rates is variable and can have a significant impact on the investigation and interpretation of potential biological processes (e.g., predation and starvation) influencing the survival of larval fish. We predicted that the average correction to the instantaneous mortality rate due to advection and diffusion should be proportional to A−1/2, where A is the area of system under study. This highlights the susceptibility of small systems to estimation error of mortality rates caused by short-term variations in physical forcing.

Phytoplankton species turnover controlled by physical forcing at different time scales

2008 ◽  
Vol 65 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Alexandrine Pannard ◽  
Myriam Bormans ◽  
Yvan Lagadeuc
Keyword(s):  
Species Composition ◽  
Time Scale ◽  
Phytoplankton Community ◽  
Diversity Index ◽  
Species Turnover ◽  
Rate Of Change ◽  
Original Structure ◽  
Short Term ◽  
Physical Forcing ◽  
Physical And Chemical

Changes in the physical and chemical environment induced by forcing events such as wind and rain can control the short-term dynamics of the phytoplankton community of inland waters. In two temperate reservoirs, species composition, diversity index, and species dynamics were characterized over periods of 3 weeks during different seasons, in parallel with changes in the physical and chemical structure of the water column. Dominant species and diversity index were shown to be controlled by environmental factors fluctuating on a seasonal and weekly time scale, whereas some rarer species responded to wind events and were indicators of a very short-term environmental change. As a consequence of the response of indicator species, the rate of change in species composition increased following meteorological events. Shifts in species composition were observed during each sampling period, except during the strongest stratification period. The shifts were associated with a modification of resource availability or intensity of stratification. We found that the resistance of the phytoplankton community to short-term physical forcing by wind increased with intensity of stratification. After the forcing event, the community did not return to its original structure because of modifications of the physical and chemical conditions induced by meteorological forcing on a weekly time scale.

An Appraisal of the Size-Dependent Mortality Hypothesis for Larval Fish: Comparison of a Multispecies Study with an Empirical Review

1993 ◽  
Vol 50 (10) ◽  
pp. 2166-2174 ◽  
Author(s):  
Pierre Pepin
Keyword(s):  
Growth Rate ◽  
Larval Fish ◽  
Mortality Rates ◽  
Accurate Information ◽  
Constant Growth Rate ◽  
Size Dependent ◽  
Conception Bay ◽  
Biased Estimates ◽  
Constant Growth ◽  
Dependent Mortality

This study presents an assessment of the size-dependent mortality hypothesis for larval fish from a multispecies survey of Conception Bay, Newfoundland, Canada. Mortality rates are estimated using a length-based method (per millimetre). The results from this survey are consistent with previous studies which indicate that losses decrease with increasing size of fish. However, for each species within this survey, mortality rates are constant. Comparison of mortality rates within species among surveys indicates that as the range of size categories sampled increases, the estimated mortality rates decrease, despite evidence of adequate fit to the length-based model. The findings indicate that previous relationships between size or stage and mortality of larval fish should be reevaluated. Length-based methodology used to estimate mortality rates of larval fish appears to provide biased estimates of this vital characteristic. It is suggested that using size as a proxy for biological age (i.e., assuming a constant growth rate) may be an invalid assumption. Future surveys will need to provide accurate information about the age structure of larvae sampled in order to properly estimate mortality rates.

scholarly journals Ichthyoplankton Species Composition and Assemblages From the Estuary to the Hukou Section of the Changjiang River

2021 ◽  
Vol 8 ◽  
Author(s):  
Di-an Fang ◽  
Xiang-ping Xue ◽  
Dong-po Xu ◽  
Xiao-hao Wang ◽  
Ning-ze Sun ◽  
...  
Keyword(s):  
Species Composition ◽  
Water Temperature ◽  
Water Level ◽  
Fish Species ◽  
Larval Fish ◽  
Fish Larvae ◽  
Changjiang River ◽  
The Changjiang River ◽  
Level Increase ◽  
Daily Rate

Estuary river–lake (ERL) complex is critical for the development of ichthyoplankton, which plays an essential role in the breeding, nursing, and recruitment of freshwater fish species. In this study, different ERL sections were selected to investigate the ichthyoplankton assemblage from the Changjiang River estuary to its Hukou section between May 2018 and August 2020. During the study period, fish larvae of 40, 35, 54, and 46 fish species were sampled in the Rugao (RG), Nanjing (NJ) (nearby estuary), Anqing (AQ), and Hukou (HK) (connected river–lake) sections in the Changjiang River, respectively. Results on ichthyoplankton surveys revealed fluctuating assemblage patterns in the different river sections; larval fish species composition presented ecological habitat-dependent characteristics, which supported the importance of ERL complex for ichthyoplankton development. Furthermore, the density of fish larvae was negatively correlated with water transparency but positively correlated with water temperature, the daily rate of water level increase, and runoff in the limitative range. A generalized additive model analysis indicated that the hydrological factors significantly affecting larval fish abundance are water temperature, transparency, the daily rate of water level increase, and runoff (p < 0.05). These results also indicated that river estuaries and river–lake connected complexes are essential for ichthyoplankton recruitment and migration. In combination with the historical record, ichthyoplankton assemblage’s patterns in the Changjiang River lower reaches were preliminarily elucidated, although additional works are needed such as assessing effects on their survival and recruitment.

Temporal Prediction Errors Affect Short-Term Memory Scanning Response Time

2016 ◽  
Vol 63 (6) ◽  
pp. 333-342
Author(s):  
Roberto Limongi ◽  
Angélica M. Silva
Keyword(s):  
Response Time ◽  
Short Term Memory ◽  
Estimation Error ◽  
Predictive Coding ◽  
Time Estimation ◽  
Prediction Errors ◽  
Memory Scanning ◽  
Short Term ◽  
Term Memory ◽  
Temporal Prediction

Abstract. The Sternberg short-term memory scanning task has been used to unveil cognitive operations involved in time perception. Participants produce time intervals during the task, and the researcher explores how task performance affects interval production – where time estimation error is the dependent variable of interest. The perspective of predictive behavior regards time estimation error as a temporal prediction error (PE), an independent variable that controls cognition, behavior, and learning. Based on this perspective, we investigated whether temporal PEs affect short-term memory scanning. Participants performed temporal predictions while they maintained information in memory. Model inference revealed that PEs affected memory scanning response time independently of the memory-set size effect. We discuss the results within the context of formal and mechanistic models of short-term memory scanning and predictive coding, a Bayes-based theory of brain function. We state the hypothesis that our finding could be associated with weak frontostriatal connections and weak striatal activity.

The box-balance model: a new tool to assess fish larval survival, applied to field data on two small pelagic fish

2020 ◽  
Vol 650 ◽  
pp. 289-308 ◽  
Author(s):  
V Raya ◽  
J Salat ◽  
A Sabatés
Keyword(s):  
Field Data ◽  
Fish Larvae ◽  
Larval Growth ◽  
Warming Trend ◽  
Mortality Rates ◽  
Larval Survival ◽  
Pelagic Fish ◽  
Balance Model ◽  
Small Pelagic Fish ◽  
Mesoscale Structures

This work develops a new method, the box-balance model (BBM), to assess the role of hydrodynamic structures in the survival of fish larvae. The BBM was applied in the northwest Mediterranean to field data, on 2 small pelagic fish species whose larvae coexist in summer: Engraulis encrasicolus, a dominant species, and Sardinella aurita, which is expanding northwards in relation to sea warming. The BBM allows one to quantify the contribution of circulation, with significant mesoscale activity, to the survival of fish larvae, clearly separating the effect of transport from biological factors. It is based on comparing the larval abundances at age found in local target areas, associated with the mesoscale structures (boxes), to those predicted by the overall mortality rate of the population in the region. The application of the BBM reveals that dispersion/retention by hydrodynamic structures favours the survival of E. encrasicolus larvae. In addition, since larval growth and mortality rates of the species are required parameters for application of the BBM, we present their estimates for S. aurita in the region for the first time. Although growth and mortality rates found for S. aurita are both higher than for E. encrasicolus, their combined effect confers a lower survival to S. aurita larvae. Thus, although the warming trend in the region would contribute to the expansion of the fast-growing species S. aurita, we can confirm that E. encrasicolus is well established, with a better adapted survival strategy.

Development of a Technique for Short-Term Prediction of Hydrometeors Using Advection and Physical Forcing.

1983 ◽  
Author(s):  
Gregory S. Forbes ◽  
John J. Cahir ◽  
Paul B. Dorian ◽  
Walter D. Lottes ◽  
Kathy Chapman
Keyword(s):  
Short Term ◽  
Physical Forcing ◽  
Term Prediction ◽  
Short Term Prediction

scholarly journals Selection Response in Finite Populations

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1961-1974 ◽  
Author(s):  
Ming Wei ◽  
Armando Caballero ◽  
William G Hill
Keyword(s):  
Linkage Disequilibrium ◽  
Inbreeding Depression ◽  
Genetic Variance ◽  
Relative Rate ◽  
Selection Response ◽  
Rate Of Change ◽  
Effective Population ◽  
Short Term ◽  
Model Account

Formulae were derived to predict genetic response under various selection schemes assuming an infinitesimal model. Account was taken of genetic drift, gametic (linkage) disequilibrium (Bulmer effect), inbreeding depression, common environmental variance, and both initial segregating variance within families (σAW02) and mutational (σM2) variance. The cumulative response to selection until generation t(CRt) can be approximated asCRt≈R0[t−β(1−σAW∞2σAW02)t24Ne]−Dt2Ne,where Ne is the effective population size, σAW∞2=NeσM2 is the genetic variance within families at the steady state (or one-half the genic variance, which is unaffected by selection), and D is the inbreeding depression per unit of inbreeding. R  0 is the selection response at generation 0 assuming preselection so that the linkage disequilibrium effect has stabilized. β is the derivative of the logarithm of the asymptotic response with respect to the logarithm of the within-family genetic variance, i.e., their relative rate of change. R  0 is the major determinant of the short term selection response, but σM2, Ne and β are also important for the long term. A selection method of high accuracy using family information gives a small Ne and will lead to a larger response in the short term and a smaller response in the long term, utilizing mutation less efficiently.

scholarly journals Fish larvae exploit edge vortices along their dorsal and ventral fin folds to propel themselves

2016 ◽  
Vol 13 (116) ◽  
pp. 20160068 ◽  
Author(s):  
Gen Li ◽  
Ulrike K. Müller ◽  
Johan L. van Leeuwen ◽  
Hao Liu
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Bony Fish ◽  
The Body ◽  
Functional Explanation ◽  
Image Velocimetry ◽  
Median Fins

Larvae of bony fish swim in the intermediate Reynolds number ( Re ) regime, using body- and caudal-fin undulation to propel themselves. They share a median fin fold that transforms into separate median fins as they grow into juveniles. The fin fold was suggested to be an adaption for locomotion in the intermediate Reynolds regime, but its fluid-dynamic role is still enigmatic. Using three-dimensional fluid-dynamic computations, we quantified the swimming trajectory from body-shape changes during cyclic swimming of larval fish. We predicted unsteady vortices around the upper and lower edges of the fin fold, and identified similar vortices around real larvae with particle image velocimetry. We show that thrust contributions on the body peak adjacent to the upper and lower edges of the fin fold where large left–right pressure differences occur in concert with the periodical generation and shedding of edge vortices. The fin fold enhances effective flow separation and drag-based thrust. Along the body, net thrust is generated in multiple zones posterior to the centre of mass. Counterfactual simulations exploring the effect of having a fin fold across a range of Reynolds numbers show that the fin fold helps larvae achieve high swimming speeds, yet requires high power. We conclude that propulsion in larval fish partly relies on unsteady high-intensity vortices along the upper and lower edges of the fin fold, providing a functional explanation for the omnipresence of the fin fold in bony-fish larvae.

scholarly journals Investigating the Broken-Heart Effect: a Model for Short-Term Dependence between the Remaining Lifetimes of Joint Lives

2012 ◽  
Vol 7 (2) ◽  
pp. 236-257 ◽  
Author(s):  
Jaap Spreeuw ◽  
Iqbal Owadally
Keyword(s):  
Mortality Rates ◽  
Short Term ◽  
Numerical Work ◽  
Data Set ◽  
Multiple State ◽  
Multiple State Model ◽  
Insurance Data ◽  
Over Time ◽  
Assurance Contracts

AbstractWe analyze the mortality of couples by fitting a multiple state model to a large insurance data set. We find evidence that mortality rates increase after the death of a partner and, in addition, that this phenomenon diminishes over time. This is popularly known as a “broken-heart” effect and we find that it affects widowers more than widows. Remaining lifetimes of joint lives therefore exhibit short-term dependence. We carry out numerical work involving the pricing and valuation of typical contingent assurance contracts and of a joint life and survivor annuity. If insurers ignore dependence, or mis-specify it as long-term dependence, then significant mis-pricing and inappropriate provisioning can result. Detailed numerical results are presented.

scholarly journals Osmotic induction improves batch marking of larval fish otoliths with enriched stable isotopes

2014 ◽  
Vol 71 (9) ◽  
pp. 2530-2538 ◽  
Author(s):  
Emmanuel de Braux ◽  
Fletcher Warren-Myers ◽  
Tim Dempster ◽  
Per Gunnar Fjelldal ◽  
Tom Hansen ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Salmo Salar ◽  
Larval Fish ◽  
Fish Larvae ◽  
Cost Effective ◽  
Industrial Applications ◽  
Chemical Markers ◽  
Potential Applications ◽  
Recent Method ◽  
Batch Marking

Abstract Otolith marking with enriched stable isotopes via immersion is a recent method of batch marking larval fish for a range of research and industrial applications. However, current immersion times and isotope concentrations required to successfully mark an otolith limit the utility of this technique. Osmotic induction improves incorporation and reduces immersion time for some chemical markers, but its effects on isotope incorporation into otoliths are unknown. Here, we tested the effects of osmotic induction over a range of different isotope concentrations and immersion times on relative mark success and strength for 26Mg:24Mg, 86Sr:88Sr and 137Ba:138Ba on Atlantic salmon (Salmo salar) larvae. 71% and 100% mark success were achieved after 1 h of immersion for 86Sr (75 µg L−1) and 137Ba (30 µg L−1) isotopes, respectively. Compared with conventional immersion, osmotic induction improved overall mark strength for 86Sr and 137Ba isotopes by 26–116%, although this effect was only observed after 12 h of immersion and predominately for 86Sr. The results demonstrate that osmotic induction reduces immersion times and the concentrations of isotope required to achieve successful marks. Osmotically induced isotope labels via larval immersion may prove a rapid and cost-effective way of batch marking fish larvae across a range of potential applications.

Sign in / Sign up

Export Citation Format

Share Document