Instantaneous Growth Rate Method Research Articles

Seasonal variation of growth and reproduction of the subarctic krill species, Thysanoessa raschii, driven by environmental conditions in the Estuary and Gulf of St. Lawrence

Abstract The aim of this study was to quantify somatic growth and reproduction of Thysanoessa raschii in response to environmental conditions in the St. Lawrence Estuary and Gulf of St. Lawrence, Canada. We sampled between 2010 and 2016 from spring to late summer and incubated individuals. Fresh molts were collected daily and measured to calculate the growth increment following the instantaneous growth rate method while eggs were counted daily. Our results showed a seasonal pattern of somatic growth and reproduction driven by temperature and chl. a concentration with a decrease in somatic growth in August when egg production was maximal, suggesting a trade-off. Functional relationship analyses revealed a narrow optimal temperature window for somatic growth with maximum temperatures observed between 1.2 and 2.0°C in the cold intermediate layer (50–150 m). Maximum egg production was observed at temperatures between 3.8 and 5.7°C in the surface layer (0–50 m). A required minimum concentration of chl. a of 9 mg.m−3 for somatic growth was observed. For egg production, the minimum observed was integrated chl. a (0–50 m) of 80 mg.m−2. We also observed the importance of optimal conditions lasting for one to 3 weeks to support biological processes in T. raschii.

First measurements of euphausiid growth rates in the northern Humboldt Current (23ºS)

One hundred and five juveniles and adults of Euphausia mucronata were incubated in order to estimate their daily growth rates (DGR) using the standard instantaneous growth rate method. From 77 krill that survived after 2 days of incubation under laboratory conditions, 70 individuals molted (35.1% males, 64.9% females). E. mucronata mean intermolt period was 5.2 days (range = 4-9 d) with mean DGR of 0.01 mm d-1 for males and -0.04 mm d-1 for females. Overall mean DGR was -0.02 mm d-1. DGRs were positive (31%), zero (12%) and negative (57%). DGR<0 evidenced body shrinking process suggesting that environmental conditions in austral autumn 2010 were unfavorable for the krill population. However, because females had DGR<0 values more frequently than males it is probable that females also used part of their energy on gonad development rather than body growth.

Instability analysis of shear bands using the instantaneous growth-rate method

Shear banding, as an unstable process of localization, is a common precursor to fracture in materials under high strain rate loadings, making the detection of the instability point after which localization will occur of significant importance. Stability analysis based on the perturbation method or the acoustic tensor have been employed. However, these methodologies are limited to certain class of problems and are difficult to generalize.In this work we propose an alternative for identifying the instability point by employing the concept of generalized stability analysis. In this framework, a stability measure is obtained by computing the instantaneous growth rate of the vector tangent to the solution. Such an approach is more appropriate for non-orthogonal problems and is easier to generalize to difficult dynamic fracture problems.Under conditions where the local instability triggers the non-homogeneous solution growth, i.e. problems that are homogeneous until the appearance of local instability, the generalized stability analysis and the modal stability analysis will closely match. Therefore, the non-homogeneous growth can be approximated by the Rayleigh Quotient of the vector tangent to the solution, which is easier to compute.We show that for a particular class of problems that respect the aforementioned conditions, in 1D and 2D examples, both quantities successfully find the instability point predicted analytically and validated experimentally in past literature results. This methodology is general and can be applied to a wide array of dynamic fracture problems, for which instability that leads to localization is important.

Population dynamics and production of &lt;i&gt;Bellamya aeruginosa&lt;/i&gt; (Reeve) (Mollusca: Viviparidae ) in Lake Donghu, Wuhan

Bellamya aeruginosa (Reeve) is a predominant benthic macroinvertebrate in many shallow lakes along the middle and lower basins of the Yangtze River, and there is little published information on its production in China by far. This paper dealed with the population dynamics and production of B. aeruginosa, a subtropical, shallow, eutrophic lake located near the middle reaches of the Yangtze River. B. aeruginosa was sampled monthly at the eleven stations in Lake Donghu from June 1998 to May 1999. The results showed that the annual average density and biomass were 92.2ind./m2 and 142.83g/m2, respectively, and the density and biomass peaks were observed in June(157ind./m2) and in November(205.78g/m2), respectively. B. aeruginosa population was composed of five year classes, among which the 1998 year class was dominant. The annual production of the animal calculated by instantaneous growth rate method was 91.56g/m2 in wet weight and 5.32g/m2 in dry weight (unshelled), and corresponding annual P/B ratio was 0.64. The production and P/B ratio of B. aeruginosa in the present paper were moderate among the values reported. The study on dynamic of mean daily production of B. aeruginosa showed that the accumulation of production of B. aeruginosa occurred in Spring, Summer and Autumn, and the value of 1998 year class was dominant in the total production.

Natural growth rates in Antarctic krill (Euphausia superba): I. Improving methodology and predicting intermolt period

The growth rates of postlarval krill (Euphausia superba) were measured across a wide range of environments in the Scotia Sea and around South Georgia using the Instantaneous Growth Rate (IGR) method. Each IGR experiment determined the intermolt period (IMP) and growth increment at molt (GI) of an average of 120 individuals incubated for 5 d in through-flowing ambient, filtered seawater. We examined the results from 51 IGR experiments involving 5,927 animals ranging between 25 mm and 62 mm. Animals were collected from an area that covered a latitudinal range of 108 and surface temperatures of between 20.858C and 4.758C. The measurement of IMP has rarely been achieved in IGR experiments because synchronous molting biases estimates. We overcame this by applying a binary logistic regression model to our data. This related IMP to temperature, body length, and maturity stage. Food did not influence IMP. Our model estimated that krill within our experiments had IMPs ranging from 9 d to 57 d. Temperature affected the IMP of females more than that of males. The IMPs of females were shortest around 28C and increased at lower and higher temperatures. IMP increased with body size and altered according to gender, with male IMPs being 50% longer than those of equivalently sized females. One of the main assumptions of the IGR method is that the GI measured in the first few days reflects the in situ conditions experienced by krill in the previous intermolt period. However, we found that the GIs declined immediately and rapidly after capture, particularly when growth was initially high. Thus, conditions at time of molt also influence GI. We developed a method of correcting measured GIs to natural growth in field conditions. These refinements toIGR methodology (IMP and GI estimation) enable more accurate and precise predictions of krill growth rates in summer to be made.

Natural growth rates in Antarctic krill (Euphausia superba): II. Predictive models based on food, temperature, body length, sex, and maturity stage

We used the instantaneous growth rate method to determine the effects of food, temperature, krill length, sex, and maturity stage on in situ summer growth of krill across the southwest Atlantic sector of the Southern Ocean. The main aims were to examine the separate effects of each variable and to generate a predictive model of growth based on satellite-derivable environmental data. Both growth increments in length on moulting (GIs) and daily growth rates (DGRs, mm d 21 ) ranged greatly among the 59 swarms, from 0.58‐15% and 0.013‐0.32 mm d 21 . However, all swarms maintained positive mean growth, even those in the low chlorophyll a (Chl a) zone of the central Scotia Sea. Among a suite of indices of food quantity and quality, large-scale monthly Chl a values from SeaWiFS predicted krill growth the best. Across our study area, the great contrast between bloom and nonbloom regions was a major factor driving variation in growth rates, obscuring more subtle effects of food quality. GIs and DGRs decreased with increasing krill length and decreased above a temperature optimum of 0.58C. This probably reflects the onset of thermal stress at the northern limit of krill’s range. Thus, growth rates were fastest in the ice edge blooms of the southern Scotia Sea and not at South Georgia as previously suggested. This reflects both the smaller size of the krill and the colder water in the south being optimum for growth. Males tended to have higher GIs than females but longer intermoult periods, leading to similar DGRs between sexes. DGRs of equivalent-size krill tended to decrease with maturity stage, suggesting the progressive allocation of energy toward reproduction rather than somatic growth. Our maximum DGRs are higher than most literature values, equating to a 5.7% increase in mass per day. This value fits within a realistic energy budget, suggesting a maximum carbon ration of ;20% d 21 . Over the whole Scotia Sea/South Georgia area, the gross turnover of krill biomass was ;1% d 21

Growth rates of Antarctic krill, Euphausia superba: Comparison of the instantaneous growth rate method with nitrogen and phosphorus stoichiometry

Zooplankton growth rates are hard to measure directly, and proxy measurements are desirable to encompass the variety of species and scales of interest. The growth rate hypothesis of stoichiometric theory states that a negative relationship exists between nitrogen : phosphorus (N : P) stoichiometry and growth rate, driven by cellular ribosomal ribonucleic acid (rRNA) content. Despite the wealth of literature on the growth rate hypothesis, there exist no practical demonstrations of its use in the marine literature. We thus investigated whether this hypothesis could be the basis of a technique to estimate growth rates of Euphausia superba by comparing, for the same individual krill, elemental stoichiometry and growth rates derived from the instantaneous growth rate (IGR) method. These growth rates were the first IGR measurements from South Georgia; from within a restricted area over the course of just 1 month, these rates were highly variable, from negative to near maximum rates recorded for the species. Although there were significant differences in N: P ratio and phosphorus content between individuals and schools, there was no relationship between N: P ratio and growth rate when data were grouped by school. Thus, our data do not support the predictions of the growth rate hypothesis at an intraspecific scale. However, when all data were pooled, the mean values of growth rate and N: P ratio did fit the interspecific relationship established previously for freshwater zooplankton. We suggest that krill maintain the biochemical machinery for high growth potential and maintain high growth in summer to take advantage of short‐term fluctuations in food.

Earthworm secondary production and N flux in agroecosystems: a comparison of two approaches.

Production was estimated for Aporrectodea spp. and Lumbricus spp. populations in corn agroecosystems with a 5-year history of manure or inorganic fertilizer applications during 1994-1995 and 1995-1996. Earthworm biomass and production were greater in manure than inorganic fertilizer plots, although biomass and production declined by about 50% between 1994-1995 and 1995-1996 due to unfavorable climatic conditions. Production was highest during the spring and autumn when soil temperatures were between 4 and 22°C. Production was higher in Lumbricus spp. than Aporrectodea spp. populations due to greater Lumbricus spp. biomass. Aporrectodea spp. production was 3.47-16.14 g ash-free dry weight (AFDW) m-2 year-1, while Lumbricus spp. production was 6.09-18.11 g AFDW m-2 year-1, depending on the fertilizer treatment and the method used to estimate production. However, production estimates from the instantaneous growth rate method were within 27% of the values calculated using the size-frequency method. Nitrogen flux through earthworms was used to estimate efficiency quotients. Net production efficiency (P/A) ranged from 0.64 to 0.76, assimilation efficiency (A/C) ranged from 0.1 to 0.3, and gross production efficiency (P/C) ranged from 0.06 to 0.22. Annual N flux through earthworm populations was higher in manure than inorganic fertilizer plots, and ranged from 2.95 to 5.47 g N m-2 year-1 in 1994-1995 and 1.76 to 2.92 g N m-2 year-1 in 1995-1996. The N flux through earthworms represented an amount equivalent to 16-30% of crop N uptake during 1994-1995 and 11-18% of crop N uptake during 1995-1996. We concluded that the effects of earthworms on N cycling in corn agroecosystems were substantial, and that N flux through earthworms was influenced significantly by fertilizer amendments.

Annual Production of &lt;i&gt;Bellamya aeruginosa&lt;/i&gt; in Houhu Lake, Wuhan

1996-1997年对后湖铜锈环棱螺进行了周年研究,结果表明其种群含三个年龄组,其中1996年组生长最快,其去壳干重瞬时生长率为2.80.采用瞬时生长率法测算其周年生产量为:带壳湿重33.13g m^-2a^-1;去壳千重1.932g m^-2a^-1;P/B系数为0.85.;An investigation on one of the dominant species of gastropods, Bellamya aeruginosa in Houhu Lake, Wuhan was carried out from April, 1996 to March, 1997.The results showed that the population was composed of three year classes, among which the 96 year class grew most quickly, with instantaneous growth rate of dry weight (unshelled) 2.80.The annual production of the animal calculated by instantaneous growth rate method was: wet weight, 33.13 g m^-2a^-1;dry weight (unshelled), 1.932 g m^-2a^-1.The corresponding annual P/B ratios was 0.85.

Feeding rates and productivity of the copepod Acartia bifilosa in a highly turbid estuary; the Gironde (SW France)

Acartia spp. are the dominant copepod species in the Gironde estuary, seaward of the turbidity maximum area. Acartia bifilosa develop a large population in spring and early summer whereas Acartia tonsa appear in late summer. High values and high variability of chlorophyll a/suspended particulate matter ratio are found seaward of the turbidity maximum area. Feeding rates of A. bifilosa were measured by fluorometry. Phytoplankton ingestion was found to be highly variable, between 8 to 80% of copepod carbon body weight. Except for adult females, copepods were heavier in summer than in winter. PB ratios, estimated by the instantaneous growth rate method, varied from 0.03 d−1 to 0.14 d−1. The gut contents and P/B ratios of Acartia bifilosa were related to chl a/SPM ratio. From those data, and a few obtained for A. tonsa, it is concluded that only in summer months phytoplankton ingestion is enough to maintain secondary production.

Modular microcomputer software to estimate fish population parameters, production rates and associated variance

Abstract– Microcomputer software to estimate fish population parameters, production rates, and associated variances was developed using established procedures. Pop/Pro Modular Statistical Software is a series of portable programs written in English that run on Macintosh(R) or IBM(R) (and compatible) computers. Population parameters can be estimated using either a single‐census mark‐recapture method or a removal method. Production and component parameters can be estimated with either the instantaneous growth rate method or the increment summation method. Output may be stratified by fish length, age or sampling interval and includes variance estimates for all parameters. The software was developed for use with fish data but may be applicable to other taxa.

Aragonite production by pteropod molluscs in the subarctic Pacific

Daily aragonite production of thecosomatous pteropods in the subarctic Pacific was estimated using the instantaneous growth rate and size-frequency methods. At Ocean Sta. PAPA during July 1985, samples for production estimates of two pteropod species, Clio pyramidata and Limacina helicina, were collected in plankton tows using nets of different mesh sizes (303, 150 and 73 μm) to include all size classes of pteropods. Estimates of calcium carbonate biomass of C. pyramidata and Limacina helicina were 67 and 155 mg CaCO 3 m −2, respectively. For the instantaneous growth rate method, shell growth of C. pyramidata was measured in 45Ca uptake experiments with diver-collected animals. For L. helicina, the rate of shell calcification was calculated from literature values on changes in mean shell diameter and the allometric relationship between shell weight and shell diameter. Aragonite production, calculated by the instantaneous growth rate method, was 1.8 mg CaCO 3 m −2 d −1 for C. pyramidata and 2.6 mg CaCO 3 m −2 m −2 d −1 for L. helicina. In comparison, aragonite production estimated by the size-frequency method was 1.4 mg CaCO 3 m −2 d −1 for C. pyramidata. The aragonite production estimate of 4.4 mg CaCO 3 m −2 d −1, determined by the instantaneous growth rate method, was 50% of the published estimate of foraminifera flux collected in a deep sediment trap at Sta. PAPA during the time of this study. Based on a model of annual production, pteropod aragonite accounts for 4–13% of the estimated total CaCO 3 production of 12–20 g CaCO 3 m −2 y −1. Results of the model suggest that coccolithophorids are the major producers of CaCO 3 at Sta. PAPA, contributing 59–77% of the estimated total CaCO 3 production.

SECONDARY PRODUCTION OF GAMMARUS MUCRONATUS SAY (AMPHIPODA: GAMMARIDAE) IN WARM TEMPERATE ESTUARINE HABITATS, YORK RIVER, VIRGINIA

ABSTRACT Secondary production of the amphipod Gammarus mucronatus was studied in a sea-grass (Zostera marina) habitat and a macroalgal fouling community on old pier pilings. Populations of G. mucronatus were present in the macroalgal habitat during only 4 months of the year with a production of 10.2-12.9 g dry wt · m―2 · yr―1 compared with 5.0-6.5 g dry wt · m―2. yr―1 in the sea-grass habitat, where populations were maintained throughout the year. Rapid growth to maximum size results in short cohort production intervals (CPI) with annual production to mean biomass ratios (P/B) ranging from 36.8-76.8. A modified instantaneous growth rate method gave production estimates that were approximately 25% higher than estimates using a size-frequency method. Production estimates using 4 different variations of the size-frequency method produced similar results. The sum of size-frequency estimates when males and females were considered separately results in slightly lower production values than combined calculations since dimorphic size biases are excluded. The results of this study indicate a need to evaluate carefully the productivity of tropical and warm and cool temperate habitats, since rapid growth of organisms such as amphipods could result in extremely high production estimates even where standing stock is low.

Life history and production of Ephoron album (Say) (Ephemeroptera: Polymitarcidae) in the Valley River, Manitoba

Ephoron album was the dominant summer mayfly in shallow riffles in the agricultural zone of the Valley River, Manitoba, in 1982 and 1983. There was one generation per year; eggs deposited in August hatched in late May of the following year and nymphs developed rapidly during the summer months. The eggs required a cold period to promote hatching and hatching success of eggs treated in the laboratory at −2 °C for varying periods of time was positively correlated to the length of the exposure period. No eggs hatched following exposure to 4 or 10 °C. Production for 1982 was estimated by four methods for the production interval of only 72 days: the instantaneous growth rate method (1.32 ± 0.44 g fresh dry weight∙m−2∙year−1), the Allen curve method (1.32 g∙m−2∙year−1), the removal – summation method (1.43 ± 0.41 g∙m−2∙year−1), and the size–frequency method (1.48 ± 0.51 g∙m−2∙year−1). Confidence intervals (95%) were calculated using the method of C. C. Krueger and F. B. Martin for the size–frequency estimate of production and by bootstrapping for the removal–summation and instantaneous growth estimates.

Seasonal Production Dynamics in a Guild of Periphyton‐Grazing Insects in a Southern Appalachian Stream

Temporal partitioning has been found to be a predominant mode of ecological segregation among groups of systematically related stream insects. We extended this concept to a functionally similar but systematically diverse group of species. The life cycles and secondary production of six species of periphyton—grazing insects (scrapers) were studied in a fourth—order unshaded stream reach in the southern Appalachian Mountains. Total annual production (as ash—free dry mass) calculated with the instantaneous—growth rate method was 1195 mg/m2. The size—frequency estimates was 6.4% lower. Annual production (AFDM) by species ranged from 612 mg/m2 for Glossosoma nigrior to 10 mg/m2 for Goera fuscula. The production peaks of the six species occurred at separate points in the year, with very little overlap between species. Comparison with a neutral model indicated that production peaks were significantly more regularly spaced (P &lt;.1) than would be expected by chance alone. Temporal overlap between species was calculated using density, biomass, and production. Overlaps based on density and biomass were similar (means of .173 and .171, respectively). Mean overlap based on production was significantly lower (.124). The patterns of temporal organization observed in this group of species were linked with specialized life histories. Five of the six species were univoltine, with periods of larval development (cohort production intervals [CPI] ranging from 44 to 215 d. The shortest CPIs were associated with species that diapaused in the egg (Agapetus sp.) or larval (Neophylax consimilis) stages. Summer production was dominated by G. nigrior, which had a bivoltine life cycle. Production by the spring—summer cohort of G. nigrior was 4.5 ° the production of the winter cohort. Glossosoma's bivoltinism apparently provides it with the life history flexibility to utilize the high summer periphyton production permitted by the lack of canopy cover at the study site. Seasonal production by the six species was distributed 18% in winter (January—March), 36% in spring, 38% in summer, and 8% in autumn. The seasonal distribution of grazer secondary production correlates well with previously reported seasonal dynamics of periphyton production.

Seasonal Patterns in Production and Drift of Gammarus Pseudolimnaeus in Valley Creek, Minnesota

The stream amphipod, Gammarus pseudolimnaeus Bousfield, was sampled monthly for five consecutive years, 1968—1973, in Valley Creek, Minnesota, USA, and seasonal patterns in production rate, drift, standing stock, and growth were observed. Several modifications of the instantaneous growth rate method were attempted, and one, the Length Increment Alternative, employing size—frequency historgrams (both in numbers and biomass) to determine instantaneous growth rates, was selected as the most accurate to estimate production at approximately monthly intervals. Production, drift, and growth correlated well in a pronounced seasonal periodicity, with maxima in the warm months. A serious siltation occurred about midway in the study, reducing the population standing stock, production, and drift. During the 1st 2 yr prior to the siltation, when the stream was in normal condition, daily production (dry mass) reached summer maxima of about 0.12—0.14 g/m2, and maximum drift about 120—220 g dry mass°d—1°m—3°s—1, both falling to zero, or near, in winter. Daily instantaneous growth rate reached maxima of about 0.03 in all years, with zero growth in winter. Annual dry mass production by the Length Increment Alternative was 271, 238, 123, 57, and 91 kg/ha for the 5 yr, respectively. Calculations comparing daily drift to production indicated that production rates were sufficient to provide the observed drift without the necessity of compensatory upstream migration.

Estimate of biological production in some stream invertebrates

Abstract Annual production of invertebrates was investigated in two streams, the Hinau and Horokiwi, in the North Island of New Zealand. Estimates were based on the instantaneous growth rate method, with adjustments made according to the number of generations produced per year. Production of primary consumers (herbivores and detritus feeders) was 7.6–72.1 g.m‐2.y‐1, and of secondary consumers (predators) 0.8–11.9 g.m‐3.y‐1. In both streams the lowest production was found in tree‐shaded situations. Production: biomass ratios ranged from 5.3 to 7.9 for primary consumers, and from 3.7 to 6.5 for secondary consumers. These ratios fall within the range of results found by workers in other countries. Fish in the two streams studied feed mainly on the primary consumers and so may be competing for food with invertebrate secondary consumers.