Energy Flow and Secondary Production of the Amphipods Hyalella azteca and Crangonyx richmondensis occidentalis in Marion Lake, British Columbia

1971 ◽  
Vol 28 (5) ◽  
pp. 711-726 ◽  
Author(s):  
Jack A. Mathias
Keyword(s):  
Population Growth ◽  
Energy Flow ◽  
Standing Crop ◽  
Production Efficiency ◽  
Hyalella Azteca ◽  
Growth Efficiency ◽  
Ecological Efficiency ◽  
Net Production ◽  
Annual Basis ◽  
Predator System

The Hyalella azteca population in Marion Lake, B.C., assimilated and produced about three times as much energy as did the Crangonyx richmondensis occidentalis population from May 1966 to May 1967, but during the summer the energy flow of H. azteca was four times, and production was five times, that of C. r. occidentalis.Hyalella azteca was abundant at a depth of 1.0 m (mean summer standing crop, 1952 animals/m2), but was rare (75 animals/m2) at depths greater than 2.5 m. Growth, molting, respiration, and hence energy flow rates decreased with depth, due (in part) to lower ambient temperatures in deeper water. On an annual basis, a mean standing crop of 1.1 kcal/m2 of H. azteca assimilated 18.1 kcal/m2, respired 13.5 kcal/m2, and used 4.6 kcal/m2 in production of growth, molts, and eggs. Approximately two-thirds of the annual energy flow was completed between June and October. On an annual basis, the ecological efficiency of an H. azteca-predator system was in the range 2.5–12.5%, the net production efficiency was 25%, and the net population growth efficiency was 16%.The mean summer density of C. r. occidentalis remained constant with depth (about 283 animals/m2). Annual energy flow and production were not appreciably affected by lower temperatures in deeper water. On an annual basis, a mean standing crop of 0.7 kcal/m2 assimilated 6.5 kcal/m2, respired 5.2 kcal/m2, and used 1.4 kcal/m2 in production. Crangonyx r. occidentalis energy flow was fairly constant throughout the year. The ecological efficiency of a C. r. occidentalis-predator system was in the range 2–10.5%, the net production efficiency was 21%, and the population growth efficiency was 17% on an annual basis.

Analysis of Energy Flow and Production in an Unexploited Marine Flatfish Population

1973 ◽  
Vol 30 (11) ◽  
pp. 1717-1728 ◽  
Author(s):  
J. C. MacKinnon
Keyword(s):  
Energy Intake ◽  
Energy Flow ◽  
Analytical Approach ◽  
Total Population ◽  
Seasonal Pattern ◽  
Ecological Efficiency ◽  
Resident Population ◽  
Net Production ◽  
Production Processes ◽  
Hippoglossoides Platessoides

The seasonal pattern of production processes in an unexploited resident population of American plaice (Hippoglossoides platessoides) in St. Margaret’s Bay, N.S., was analyzed with an energetics model which represents an extension of the analytical approach used in fishery theory. During summer, production is about twice the annual net production of 1.5 kcal/m2 by fish aged 1 and up. The ecological efficiency is 17%, with larvae and 0+ fish accounting for some 20% of total population ingestion and 34% of net population production. Metabolic expenditures constitute the largest fraction (62%) of population energy intake and about 80% of this amount is consumed during summer. Plaice ingest about half the yearly estimated production (25 kcal/m2) of benthos in the deeper parts of the Bay.

scholarly journals The Relationship between China’s Financial Industry Performance and Energy Elimination

2019 ◽  
Vol 81 ◽  
pp. 01023
Author(s):  
Jun-Qi Wu ◽  
Li-Chen Chou
Keyword(s):  
Energy Consumption ◽  
Production Efficiency ◽  
Mainland China ◽  
Financial Industry ◽  
Empirical Results ◽  
Annual Basis ◽  
Average Production ◽  
Industry Performance ◽  
Research Objects ◽  
The Relationship

Taking the provinces, autonomous regions and cities in mainland China as the research objects, this paper collects and collates the data of production, input and energy consumption of the financial industry from 2009 to 2014, and analyzes the production efficiency of each region. The empirical results show that the production efficiency of all prefecture-level cities is 0.782. If analysed on region basis, the average production efficiency of prefecture-level cities is the highest in the eastern provinces, followed by the central provinces and the lowest in the western provinces. If analysed on annual basis, the distribution of production efficiency shows a trend of decline during 2009-2010 and increase after 2012.

ZOOPLANKTON OF LAKE HAZEN, ELLESMERE ISLAND, AND A NEARBY POND, WITH SPECIAL REFERENCE TO THE COPEPOD CYCLOPS SCUTIFER SARS

1964 ◽  
Vol 42 (4) ◽  
pp. 613-629 ◽  
Author(s):  
I. A. McLaren
Keyword(s):  
Special Reference ◽  
Standing Crop ◽  
Dry Weight ◽  
High Arctic ◽  
Ellesmere Island ◽  
Arctic Lakes ◽  
Net Production ◽  
Daphnia Middendorffiana ◽  
Ice Conditions ◽  
Cyclops Scutifer

Zooplankton was studied in the large, high-arctic Lake Hazen and in a small nearby pond. Primary (O2) production in Lake Hazen may have occurred largely before the ice began to melt, but was unmeasurable in summer. Primary production in the pond was about the same as in other small arctic lakes, Cyclops scutifer was overwhelmingly dominant in Lake Hazen. C. scutifer and Daphnia middendorffiana were commonest in the pond. C, scutifer is annual in Scandinavia, often with coexisting spring-born and fall-born generations. On Ellesmere Island the pond appears to contain alternating annual and biennial generations, whereas the species is strictly biennial in Lake Hazen. Numbers of C. scutifer in Lake Hazen were greatly reduced as a result of summer ice conditions between 1958 and 1961, while the rotifer Keratella hiemalis increased. Estimated mean standing crop (96 mg/m2) and net production (1.0 mg/m2 day) in dry weight ol C. scutifer in Lake Hazen during the summer of 1958 were extremely low. In early August the crop of this species in the pond was abont the same as in Lake Hazen, but net production was sonic 15 times as large, and other zooplankters added considerably to crop and production of the pond.

scholarly journals Determination of bacterioplankton biomass, net production and growth efficiency in the Southern Ocean

1991 ◽  
Vol 71 ◽  
pp. 185-194 ◽  
Author(s):  
PK Bjørnsen ◽  
J Kuparinen
Keyword(s):  
Southern Ocean ◽  
Growth Efficiency ◽  
Net Production

The primary production of aldabra atoll, with reference to habitats used by Giant Tortoises

1983 ◽  
Vol 302 (1109) ◽  
pp. 167-199 ◽  
Keyword(s):  
Primary Production ◽  
Standing Crop ◽  
Single Species ◽  
Structural Heterogeneity ◽  
Turnover Rates ◽  
Net Production ◽  
Wooded Area ◽  
Leaf Turnover ◽  
Scrub Forest

This paper reports on the seasonal changes of standing crop and production in habitats used by a high-density population of giant tortoises on Aldabra atoll. The study had two main aims: first to investigate the primary production of a raised coral atoll (to our knowledge the first such study) and secondly to provide base data for a study of the interactions of a large reptilian herbivore (the giant tortoise) with its food supply and environment. Environmental heterogeneity made it necessary to measure separately the standing crop and the above-ground net production of different components of the vegetation; these components were usually single species or small groups of species of plants. Measurements of these components were then combined with cover data for the same components in selected places to illustrate the seasonal and spatial variability of primary production on Aldabra. Standing crop biomasses were estimated from harvest samples. Methods for production estimates varied with the component studied, but included harvest difference methods, repeated clipping of the same plots and direct measurement of leaf turnover rates on marked shoots. These methods are compared where appropriate. Net annual above-ground production varied between plant types from 3165 kJ per square metre of plant for ‘tortoise turf’ to 47700 kJ m -2 for Cyperus ligularis , a robust perennial sedge. Total above-ground annual net production of different habitat types (bare ground and rocks between plants being taken into account) varied from 9100 kJ m -2 in a thinly wooded area with high tortoise turf cover (‘open mixed scrub’) to 28200 kJ m -2 in an area of thick scrub forest (‘groves’). The seasonality of production and standing crop also varied considerably between habitats, owing to the role of different components of the ground layer and shrub cover. These results are discussed in terms of the roles of environmental and structural heterogeneity in setting primary production and of the tortoises themselves in their interactions with the vegetation via trampling and grazing. The effect of this heterogeneity on sampling strategies and results is also assessed.

scholarly journals Pastoral Population Growth and Land Use Policy Has Significantly Impacted Livestock Structure in Inner Mongolia—A Case Study in the Xilinhot Region

2019 ◽  
Vol 11 (24) ◽  
pp. 7208 ◽  
Author(s):  
Ye Jiang ◽  
Qing Zhang ◽  
Jianming Niu ◽  
Jianguo Wu
Keyword(s):  
Land Use ◽  
Population Growth ◽  
Inner Mongolia ◽  
Rural Economy ◽  
Production Efficiency ◽  
Livestock Production ◽  
Land Use Policy ◽  
Livestock Industry ◽  
Horse Population ◽  
Pastoral System

The traditional livestock industry in Inner Mongolia has evolved rapidly in response to social and economic transformations during recent decades, resulting in substantial impacts on the rural economy and livelihoods of pastoralists. Improved understanding of these changes and potential drivers may help foster strategies to sustain the pastoral system of this region. Using long-term climate, social-economic, and livestock (cattle, horses, sheep, and goats) population data from 1970 to 2010, we analyzed the dynamics of the livestock industry and main driving factors in the Xilinhot region—a central part of the Inner Mongolia Grassland. Our results show that the total livestock population increased dramatically in the past four decades, especially during 1987–2010. Livestock composition also changed substantially, with increasing sheep, goat, and cattle populations but a decreasing horse population. Pastoral population growth and land use policy were the primary drivers for livestock dynamics during 1970–2010. Livestock structure became differentiated progressively with changes in land use policy. Also, climate factors had an important influence on livestock production. The current study suggests that sustainable animal husbandry in this region requires government policies that promote ecological urbanization, livestock production efficiency, incentive systems for grassland conservation, and collective action and cooperation for enhancing social capital and resilience.

Ecology of Chironomidae (Diptera) in a Polar Lake

1976 ◽  
Vol 33 (2) ◽  
pp. 227-247 ◽  
Author(s):  
H. E. Welch
Keyword(s):  
Energy Flow ◽  
Growth Efficiency ◽  
Life Cycles ◽  
Egg Laying ◽  
Larval Life ◽  
Metabolic Compensation ◽  
Class Strength ◽  
Growth Respiration ◽  
Definition Of

The six common genera of Chironomidae (Diptera) in Char Lake, Resolute, Northwest Territories (74°42′N lat.) were studied intensively from 1969 to 1972. Heterotrissocladius oliveri and a Trissocladius species are characteristic of the sediment zone, while two species of Orthocladius, Pseudodiamesa arctica, Paracladius quadrinodosus, and Lauterbornia sp. are restricted mainly to the rocky and moss zones. Life cycles are 2 or 3 yr, depending upon the species. Year-classes could be discriminated by instar frequency distribution. Populations increased steadily during the study period, for an average increase in strength of 5 times between the 1968 and 1971 year-classes. Summer emergence and egg-laying conditions are of overriding importance to year-class strength. Mortality within year-classes is undetectable until the last 4 mo of larval life, when mortality due to char predation is about 65% between April and the time of emergence. The physiology of these chironomids does not seem unusual aside from continuing activity down to 0 C, and there is no indication of metabolic compensation. Net growth efficiency averages 36%. Assimilated energy (growth + respiration) at 8.6 kcal m−2 yr−1 is very low compared with temperate zone populations, but is more similar as a percent of photosynthesis, 4.1%. The relatively large detritus pool and the presence of both 2- and 3-yr species tend to stabilize chironomid energy flow. Definition of long-term averages for chironomid populations in Char Lake would require a decade or more of study.

Energy budget for a stream population of the freshwater clam, Sphaerium striatinum Lamarck (Bivalvia: Pisidiidae)

1984 ◽  
Vol 62 (12) ◽  
pp. 2410-2417 ◽  
Author(s):  
Daniel J. Hornbach ◽  
Thomas E. Wissing ◽  
Albert J. Burky
Keyword(s):  
Energy Budget ◽  
Standing Crop ◽  
Production Efficiency ◽  
Reproductive Effort ◽  
Energy Partitioning ◽  
Minimum Size ◽  
Energy Needs ◽  
Annual Productivity ◽  
Deposit Feeding ◽  
Growth And Reproduction

An annual energy budget was constructed for a stream population of Sphaerium striatinum. The annual productivity (P) was 2.79 g C∙m−2∙year−1 and the average standing crop biomass (B) was 0.58 g C∙m−2; the resulting annual P:B ratio of 4.58 is below that expected for a bivoltine animal. The low value for reproductive effort (Re:P = 16.1%) may partially be attributed to the ovoviviparous, iteroparous nature of this population. A strategy of partitioning a large proportion of production to growth (G:P = 83.9%) may insure a high probability of attaining the minimum size necessary for reproduction. Production accounts for 44% of assimilation (A) with 56% of A lost through respiration. The net production efficiency (P:A = 44%) is high and indicates that this population is efficient in partitioning energy to growth and reproduction. The population must consume (C) 10.57 g C∙m−2∙year−1 to meet its energy needs. Only 35% of this could be accounted for by filter feeding; the remainder may have come from deposit feeding. Comparisons of P, P:B, Re:P and P:A with published values for corbiculacean clams indicates that this population of S. striatinum is one of the most productive and efficient in its energy partitioning of populations studied to date.

Sign in / Sign up

Export Citation Format

Share Document