Timing of breeding, peak food availability, and effects of mismatch on chick growth in birds nesting in the High Arctic

2012 ◽  
Vol 90 (8) ◽  
pp. 961-971 ◽  
Author(s):  
L. McKinnon ◽  
M. Picotin ◽  
E. Bolduc ◽  
C. Juillet ◽  
J. Bêty
Keyword(s):  
Food Availability ◽  
Growth Rates ◽  
Historical Data ◽  
Canadian Arctic ◽  
Growth Curves ◽  
High Arctic ◽  
Food Abundance ◽  
Trophic Levels ◽  
Timing Of Breeding ◽  
Chick Growth

In seasonal environments, breeding events must be synchronized with resource peaks to ensure production and growth of offspring. As changes in climate may affect trophic levels differentially, we hypothesized that a lack of synchrony between chick hatch and resource peaks could decrease growth rates in chicks of shorebirds nesting in the High Arctic. To test this hypothesis, we compared growth curves of chicks hatching in synchrony with peak periods of food abundance to those hatching outside of these peak periods. We also tested for changes in lay dates of shorebirds in the Canadian Arctic using recent and historical data. Mean daily temperatures during the laying period increased since the 1950s by up to 1.5 °C, and changes in lay dates were apparent for three shorebird species, yet differences in median lay dates between 1954 and 2005–2008 were only significant for White-rumped Sandpiper ( Calidris fuscicollis (Viellot, 1819)). During 2005–2008, there was only 1 year of relatively high synchrony between hatch and resource peaks. Asynchrony between hatch and peaks in Tipulidae biomass reduced growth rates in chicks of Baird’s Sandpiper (Calidris bairdii (Coues, 1861)). As anticipated changes in climate may decouple phenological events, the effects of asynchrony on growth rates of arctic-nesting birds warrant further investigation.

Estimation of salmonid habitat growth potential through measurements of invertebrate food abundance and temperature

2014 ◽  
Vol 71 (8) ◽  
pp. 1158-1170 ◽  
Author(s):  
Nicholas Weber ◽  
Nicolaas Bouwes ◽  
Chris E. Jordan
Keyword(s):  
Food Availability ◽  
Growth Rates ◽  
Food Abundance ◽  
Fish Growth ◽  
Growth Potential ◽  
Habitat Characteristics ◽  
Physical Habitat ◽  
Bioenergetics Model ◽  
Adequate Food ◽  
Consumption Rates

Criteria used to characterize lotic salmonid habitat suitability are often based on correlations between physical habitat characteristics and salmonid abundance. Focusing on physical habitat features ignores other habitat components, such as an adequate food supply, that limit the amount of energy available for growth and survival. We tested the degree that food availability and temperature influence lotic salmonid consumption and growth rates and outline an approach for assessing habitat quality based on measurements of these features. We collected benthic and drifting invertebrate abundances, stream temperatures, and juvenile steelhead – rainbow trout (Onchorhynchus mykiss gairdneri) summer growth rates among nine stream segments in central Oregon. Stream temperatures and growth rates were used in bioenergetics model simulations to estimate O. mykiss consumption rates. The variation in O. mykiss consumption rates was explained by measurements of total drift biomass along a type II predator response curve (R2 = 0.71). This simplified foraging relationship between food abundance and consumption is then used to estimate the consumption component of the bioenergetics model to allow estimation of salmonid growth potential. Validation of the growth potential model produced reasonably accurate estimates of fish growth rates at reaches within the study area and precise but biased estimates in novel systems. While additional reach-level habitat information may be required to make the model more generalizable, the assessment of invertebrate food availability offers a simple yet powerful approach for describing the growth potential of stream habitat.

scholarly journals The Behavioral Ecology of Maternal Effort in Fur Seals and Sea Lions

Behaviour ◽  
1990 ◽  
Vol 114 (1-4) ◽  
pp. 3-20 ◽  
Author(s):  
Fritz Trillmich
Keyword(s):  
Energy Transfer ◽  
Food Availability ◽  
Growth Rates ◽  
High Energy ◽  
Food Abundance ◽  
Foraging Efficiency ◽  
Intake Rate ◽  
Sea Lions ◽  
Fur Seals ◽  
Pup Growth

AbstractOtariid seals form a group of similar species distributed from subpolar to tropical seas. Many species were recently studied under conditions of low and high food abundance during major oceanographic disturbances. Evidence for the phenotypic flexibility of and constraints on the rearing strategy of these species derives from inter- and intra-specific comparisons and experimental measurements. I review how changes in food abundance influence foraging behavior and energetics of mothers, pup growth rates, milk composition, weaning age, and the fertility cost of pup rearing. Eared seal females rear young by alternating between lactation ashore and foraging at sea. Subpolar fur seals always wean pups at four month of age, a trait which seems to be genetically fixed and adaptive in their highly seasonal environment. Temperate and tropical fur seals and sea lions can respond to changes in food abundnace by increasing or decreasing time to weaning. During pup rearing, mothers regulate body mass to different absolute values when abundance of food resources changes. This seems to be a constraint caused by reduced foraging efficiency at low food availability. Most species feed exclusively during the night, but sea lions (Zalophus californianus) and Northern fur seals (Callorhinus ursinus) also forage during the day by diving deeper. Females of some species increase the rate of at-sea energy expenditure at low food abundance while keeping the duration of foraging trips constant. Females of other species stay at sea longer working at the same rate. The latter species may be food specialist with a narrower time window for efficient foraging. Pups grow slower when mothers increase time at sea, and at very low food abundance pups may starve. Pups have little influence on the duration of maternal foraging trips, but may diminish the mothers' time ashore by increasing the rate of milk extraction and prolonged non-nutritive sucking. The impact of long maternal at-sea times is reduced by increasing milk fat content as time at sea increases. This mechanism does not fully compensate pup energy intake rate for longer trip durations. Non-migratory species can partly compensate for reduced pup growth rates by lengthening the lactation period. In the Galapagos fur seal (A. galapagoensis), this entails a considerable cost to the mother by reducing her future fertility. Lactation reduces the probability of a successful simultaneous pregnancy and, if pregnancy succeeds, sibling competition for maternal milk ensues. Competition is usually won by the older sibling leading in many cases to the death of the newborn. The rate of energy transfer to pups is high in food-rich years and low in scarce ones. Because pups are more likely to be weaned as yearlings when juvenile growth rate is high than when it is low, high energy transfer to the pup in year "a" reduces the cost of reproduction incurred in year "a+1". The flexibility of the rearing strategy of temperate and tropical species permits mothers to adjust phenotypically to variance in food availability thus partly masking the theoretically expected trade-offs in the life history of these species.

scholarly journals Life-history attributes of Arctic-breeding birds drive uneven responses to environmental variability across different phases of the reproductive cycle

2021 ◽  
Author(s):  
Daniel Ruthrauff ◽  
Vijay Patil ◽  
Jerry W. Hupp ◽  
David Ward
Keyword(s):  
Life History ◽  
Reproductive Cycle ◽  
Growth Rates ◽  
Life History Traits ◽  
Environmental Variability ◽  
Breeding Birds ◽  
Timing Of Breeding ◽  
Chick Growth ◽  
Snow Geese ◽  
Semipalmated Sandpipers

1. Animals exhibit varied life-history traits that reflect adaptive responses to their environments. For Arctic-breeding birds, traits like foraging guild, egg nutrient allocation, clutch size, and chick growth are predicted to be under increasing selection pressure due to rapid climate change and increasing environmental variability across high-latitude regions. 2. We compared four migratory birds (black brant [Branta bernicla nigricans], lesser snow geese [Chen caerulescens caerulescens], semipalmated sandpipers [Calidris pusilla], and Lapland longspurs [Calcarius lapponicus]) with varied life histories at an Arctic site in Alaska, USA, to understand how life-history traits help moderate environmental variability across different phases of the reproductive cycle. 3. We monitored aspects of reproductive performance related to the timing of breeding, reproductive investment, and chick growth from 2011–2018. 4. In response to early snow melt and warm temperatures, semipalmated sandpipers advanced their site arrival and bred in higher numbers, while brant and snow geese increased clutch sizes; all four species advanced their nest initiation dates. During chick rearing, longspur chicks were relatively resilient to environmental variation whereas warmer temperatures increased the growth rates of sandpiper chicks but reduced growth rates of snow goose goslings. These responses generally aligned with traits along the capital-income spectrum of nutrient acquisition and altricial-precocial modes of chick growth. Under a warming climate, the ability to mobilize endogenous reserves likely provides geese with relative flexibility to adjust the timing of breeding and the size of clutches. Warmer temperatures, however, may negatively affect the quality of herbaceous foods and slow gosling growth. 5. Species may possess traits that are beneficial during one phase of the reproductive cycle and others that may be detrimental at another phase, uneven responses that may be amplified with future climate warming. These results underscore the need to consider multiple phases of the reproductive cycle when assessing the effects of environmental variability on Arctic-breeding birds.

scholarly journals Biomarkers in Ringed Seals Reveal Recent Onset of Borealization in the High- Compared to the Mid-Latitude Canadian Arctic

2021 ◽  
Vol 8 ◽  
Author(s):  
Camille de la Vega ◽  
Claire Mahaffey ◽  
David J. Yurkowski ◽  
Louisa Norman ◽  
Elysia Simpson ◽  
...  
Keyword(s):  
Food Web ◽  
Trophic Position ◽  
Canadian Arctic ◽  
High Arctic ◽  
Trophic Levels ◽  
The Arctic ◽  
Food Web Structure ◽  
Web Structure ◽  
Ringed Seals ◽  
Ecological Changes

Warming of the Arctic has resulted in environmental and ecological changes, termed borealization, leading to the northward shift of temperate species. Borealization has occurred across all trophic levels, altering the structure of the food web. The onset and rate of borealization likely varies with latitude, depending on local warming and advection of warmer water into the Arctic. In order to assess latitudinal trends in food web structure in the Arctic, we analyzed stable nitrogen isotopes of specific amino acids alongside bulk stable carbon isotopes in ringed seal muscle tissue from the Canadian Arctic Archipelago (high-Arctic) and Southern Baffin Bay (mid-Arctic) from 1990 to 2016. Our results indicate a shift in food web structure in the high-Arctic that has occurred more recently when compared with the mid-Arctic. Specifically, over the past 25 years, the trophic position of ringed seals from the mid-Arctic was largely constant, whereas the trophic position of ringed seals decreased in the high-Arctic, reaching similar values observed in the mid-Arctic in 2015–2016. This suggests a potential shortening of the food chain length in the high-Arctic, possibly driven by changes in zooplankton communities feeding complexity in association with sea ice decline. This study identifies a temporal offset in the timing of borealization in the Canadian Arctic, resulting in different response of food webs to ecological changes, depending on latitude.

Evaluation of genomic sequence-based growth rate methods for synchronized Synechococcus cultures

2021 ◽  
Author(s):  
Julia Carroll ◽  
Nicolas Van Oostende ◽  
Bess B. Ward
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Dna Replication ◽  
Growth Rates ◽  
Genomic Sequence ◽  
Niche Differentiation ◽  
Trophic Levels ◽  
Individual Species ◽  
Cell Counts

Standard methods for calculating microbial growth rates (μ) through the use of proxies, such as in situ fluorescence, cell cycle, or cell counts, are critical for determining the magnitude of the role bacteria play in marine carbon (C) and nitrogen (N) cycles. Taxon-specific growth rates in mixed assemblages would be useful for attributing biogeochemical processes to individual species and understanding niche differentiation among related clades, such as found in Synechococcus and Prochlorococcus . We tested three novel DNA sequencing-based methods (iRep, bPTR, and GRiD) for evaluating growth of light synchronized Synechococcus cultures under different light intensities and temperatures. In vivo fluorescence and cell cycle analysis were used to obtain standard estimates of growth rate for comparison with the sequence-based methods (SBM). None of the SBM values were correlated with growth rates calculated by standard techniques despite the fact that all three SBM were correlated with percentage of cells in S phase (DNA replication) over the diel cycle. Inaccuracy in determining the time of maximum DNA replication is unlikely to account entirely for the absence of relationship between SBM and growth rate, but the fact that most microbes in the surface ocean exhibit some degree of diel cyclicity is a caution for application of these methods. SBM correlate with DNA replication but cannot be interpreted quantitatively in terms of growth rate. Importance Small but abundant, cyanobacterial strains such as the photosynthetic Synechococcus spp. are essential because they contribute significantly to primary productivity in the ocean. These bacteria generate oxygen and provide biologically-available carbon, which is essential for organisms at higher trophic levels. The small size and diversity of natural microbial assemblages means that taxon-specific activities (e.g., growth rate) are difficult to obtain in the field. It has been suggested that sequence-based methods (SBM) may be able to solve this problem. We find, however, that SBM can detect DNA replication and are correlated with phases of the cell cycle but cannot be interpreted in terms of absolute growth rate for Synechococcus cultures growing under a day-night cycle, like that experienced in the ocean.

scholarly journals On the Thermal Regime of a High-Arctic Valley Glacier

1976 ◽  
Vol 16 (74) ◽  
pp. 119-133 ◽  
Author(s):  
Fritz Müller
Keyword(s):  
Thermal Regime ◽  
Energy Input ◽  
Canadian Arctic ◽  
High Arctic ◽  
Canadian Arctic Archipelago ◽  
Valley Glacier ◽  
Drilling Technique ◽  
Percolation Zone ◽  
Mean Annual Air Temperature ◽  
Upper Boundary

AbstractThe 10 m temperatures were measured over several years at 16 sites on the White Glacier (lat. 80° N.), Axel Heiberg Island, Canadian Arctic Archipelago. At three sites deep profiles were made using a new drilling technique, reaching a maximum depth of 280 m. Large differences in the 10 m temperatures between locations and from year to year were observed. The deviations of these temperatures from the almost isothermal mean annual air temperature over the glacier are discussed. The heating effect of the melt water in the lower percolation zone was found to be very important. A conceptual model is developed to assess the influence of these irregularities in the energy input at the upper boundary on the thermal regime of the entire glacier. So far a quantitative analysis has been made only for the relatively simple 30 m temperature profile measured on the tongue of the glacier.

A STUDY OF RATES OF GROWTH OF YORKSHIRE, LACOMBE, LANDRACE, AND CROSSBRED PIGS FROM BIRTH TO 200 LB

1964 ◽  
Vol 44 (3) ◽  
pp. 315-319
Author(s):  
J. M. Bell
Keyword(s):  
Growth Rates ◽  
Early Life ◽  
Growth Curves ◽  
Rates Of Growth ◽  
Similar Growth ◽  
Crossbred Pigs

Growth records were obtained from 12 research establishments across Canada for pigs fed according to current (1960–63) recommendations of nutrition and management. Growth curves showing age in days and weight in pounds are presented for the various breeds and crossbreds, for between-station comparisons, for comparison of upper and lower quartiles in purebred pigs, and for comparison of growth rates of purebreds with that of Yorkshires of 20 to 25 years ago.Age at 200 lb averaged from 152 to 187 days, among 10 stations for the Yorkshire breed. Pigs of each of the pure breeds reached 200 lb about 3 weeks earlier than that indicated in previous studies. Crossbred pigs of each of four different crosses grew more rapidly than average Yorkshires, some reaching 200 lb in 140 days and having gains in excess of 2.3 lb/day during the finishing period. Yorkshire, Lacombe, and Landrace pigs had similar growth curves. The upper quartile averaged 1.8 and the lower 1.4 lb/day gain between 100 and 200 lb weights. Slow-maturing pigs tended to be below average throughout life but differences in maturity between stations seemed to reflect differing rates of gain in early life, since finishing period gains were similar in 8 of 10 stations.

scholarly journals Seasonal Acclimation Modulates the Impacts of Simulated Warming and Light Reduction on Temperate Seagrass Productivity and Biochemical Composition

2021 ◽  
Vol 8 ◽  
Author(s):  
Pedro Beca-Carretero ◽  
Tomás Azcárate-García ◽  
Marc Julia-Miralles ◽  
Clara S. Stanschewski ◽  
Freddy Guihéneuf ◽  
...  
Keyword(s):  
Growth Rates ◽  
Zostera Marina ◽  
Leaf Growth ◽  
Seawater Temperature ◽  
Trophic Levels ◽  
Experimental Warming ◽  
Omega 3 ◽  
Growth Physiology ◽  
Light Reduction ◽  
Climate Change Effects

Increases in seawater temperature and reduction in light quality have emerged as some of the most important threats to marine coastal communities including seagrass ecosystems. Temperate seagrasses, including Zostera marina, typically have pronounced seasonal cycles which modulate seagrass growth, physiology and reproductive effort. These marked temporal patterns can affect experimental seagrass responses to climate change effects depending on the seasons of the year in which the experiments are conducted. This study aimed at evaluating how seasonal acclimatization modulates productivity and biochemical responses of Zostera marina to experimental warming and irradiance reduction. Seagrass shoots were exposed to different temperatures (6, 12, 16, 20, and 24°C), combined with high (180 μmol photons m–2 s–1) and low (60 μmol photons m–2 s–1) light conditions across four seasons (spring: April, summer: July, and autumn: November 2015, and winter: January 2016). Plants exhibited similar temperature growth rates between 16 and 20°C; at 24°C, a drastic reduction in growth was observed; this was more accentuated in colder months and under low irradiance conditions. Higher leaf growth rates occurred in winter while the largest rhizomes were reached in experiments conducted in spring and summer. Increases in temperature induced a significant reduction in polyunsaturated fatty acids (PUFA), particularly omega-3 (n-3 PUFA). Our results highlight that temperate seagrass populations currently living under temperature limitation will be favored by future increases in sea surface temperature in terms of leaf and rhizome productivity. Together with results from this study on Z. marina from a temperate region, a wider review of the reported impacts of experimental warming indicates the likely reduction in some compounds of nutritional importance for higher trophic levels in seagrass leaves. Our results further demonstrate that data derived from laboratory-based studies investigating environmental stress on seagrass growth and acclimation, and their subsequent interpretation, are strongly influenced by seasonality and in situ conditions that precede any experimental exposure.

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