scholarly journals Latitudinal temperature-dependent variation in timing of prey availability can impact Pacific seabird populations in Canada

2017 ◽  
Vol 95 (3) ◽  
pp. 161-167 ◽  
Author(s):  
D.F. Bertram ◽  
A. Harfenist ◽  
L.L.E. Cowen ◽  
D. Koch ◽  
M.C. Drever ◽  
...  
Keyword(s):  
Growth Rates ◽  
Prey Availability ◽  
Gulf Of Alaska ◽  
Zooplankton Biomass ◽  
Temperature Dependent ◽  
Nestling Growth ◽  
Ocean Climate ◽  
Peak Biomass ◽  
Cassin's Auklet ◽  
Ptychoramphus Aleuticus

We modelled how nestling growth rates of Cassin’s Auklet (Ptychoramphus aleuticus (Pallas, 1811)) varied with timing of peak copepod prey availability at two breeding colonies in British Columbia: on Triangle Island, in the California Current Ecosystem, and Frederick Island, in the Gulf of Alaska Ecosystem. We used time series of nestling growth rates and estimated the seasonal timing of peak biomass of the copepod Neocalanus cristatus (Krøyer, 1848) using a temperature-dependent phenology equation. We developed a single model to examine intercolony differences in the effect of the timing of regional peak prey biomass on seabird nestling growth rates. This model indicated nestling growth rates on Triangle Island varied widely and were positively associated with timing of peak zooplankton biomass, such that higher growth rates were observed when the peak biomass occurred later in the breeding season. In contrast, nestling growth rates were consistently high at Frederick Island, where peak copepod biomass always occurred relatively late. If ocean climate warming results in a poleward shift of Neocalanus abundance and induces earlier and more narrow timing of availability, then episodes of poor nestling growth will increase in frequency on Triangle Island and could eventually affect auklets on more northerly colonies.

Stable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California

2004 ◽  
Vol 82 (10) ◽  
pp. 1578-1595 ◽  
Author(s):  
Josh Adams ◽  
John Y Takekawa ◽  
Harry R Carter
Keyword(s):  
Southern California ◽  
Prey Availability ◽  
California Current ◽  
Breeding Ecology ◽  
Foraging Area ◽  
Cassin's Auklet ◽  
Prey Resources ◽  
Ptychoramphus Aleuticus ◽  
Second Clutch ◽  
Breeding Seasons

Planktivorous seabirds readily respond to changes in marine ecosystems and have the ability to integrate information regarding variability in abundance, availability, and community composition of key prey resources. We studied the foraging and breeding ecology of the Cassin's auklet, Ptychoramphus aleuticus (Pallas, 1811), off southern California during three breeding seasons (1999–2001), when large intra- and inter-annual variability occurred in local oceanographic conditions during a prolonged La Niña event. Radio-marked parents used consistent core foraging areas within 30 km of their colony, aggregated in shelf waters (<200 m depth), and occasionally foraged in deeper waters. Parents delivered primarily euphausiids, pelagic larval-juvenile fishes, and minor amounts of cephalopods and other crustaceans. Whereas the euphausiid Thysanoessa spinifera Holmes, 1900 was most important during 1999 and 2001, Euphausia pacifica Hansen, 1911 replaced adult T. spinifera in 2000 after an anomalous eastward inflection of the California Current occurred near the auklets' foraging area. Differences in chick diets, however, did not significantly influence fledging success and growth among first chicks, but the proportion of pairs successfully fledging an alpha chick and initiating a second clutch was exceptional in 1999 (63%) and 2000 (75%), and less in 2001 (7%). We suggest that dietary composition was influenced by modified prey availability driven in part by fluctuations in regional upwelling and circulation.

scholarly journals Ocean climate and El Niño impacts on survival of Cassin's Auklets from upwelling and downwelling domains of British Columbia

2005 ◽  
Vol 62 (12) ◽  
pp. 2841-2853 ◽  
Author(s):  
Douglas F Bertram ◽  
Anne Harfenist ◽  
Barry D Smith
Keyword(s):  
British Columbia ◽  
El Niño ◽  
El Nino ◽  
Marine Ecosystem ◽  
California Current ◽  
Ocean Climate ◽  
The North ◽  
Mortality Response ◽  
Cassin's Auklet ◽  
Ptychoramphus Aleuticus

We report on the survival of populations of Cassin's Auklet (Ptychoramphus aleuticus) that breed on two oceanic colonies in British Columbia: Triangle Island, near the northern end of the California Current Ecosystem, and Frederick Island to the north in the Alaska Current Ecosystem. We captured and banded birds at both colonies from 1994 to 2000 and analyzed the recovery data with the computer program MARK. Average local adult annual survival (± standard error) was significantly lower (p = 0.0001) on Triangle Island (0.71 ± 0.02) than that on Frederick Island (0.80 ± 0.02), likely a result of poor production in the California Current Ecosystem during the 1990s. Coincident with a strong El Niño event, survival in 1997-1998 fell in unison to the lowest values observed for both colonies (to 0.54 ± 0.05 and 0.64 ± 0.04, respectively, for adults). A common winter environment in the California Current Ecosystem could explain the unified mortality response of both British Columbia populations to an exceptionally poor food period. The seabird colonies in this study occupy key positions in relation to major oceanographic domains and hence provide unique platforms for investigations of marine ecosystem response to ocean climate variability in the Northeast Pacific Ocean.

Cassin's Auklet (Ptychoramphus aleuticus)

2020 ◽  
Author(s):  
David G. Ainley ◽  
D. A. Manuwal ◽  
Josh Adams ◽  
A. C. Thoresen
Keyword(s):  
Cassin's Auklet ◽  
Ptychoramphus Aleuticus

The abundance and effects of ticks (Ixodes uriae) on nestling Cassin's Auklets (Ptychoramphus aleuticus) at Triangle Island, British Columbia

1996 ◽  
Vol 74 (8) ◽  
pp. 1585-1589 ◽  
Author(s):  
Y. E. Morbey
Keyword(s):  
Tick Infestation ◽  
Host Record ◽  
New Host ◽  
Ixodes Uriae ◽  
New Host Record ◽  
Cassin's Auklet ◽  
Peak Mass ◽  
The Common ◽  
Ptychoramphus Aleuticus ◽  
Wing Growth

Cassin's Auklet (Ptychoramphus aleuticus) nestlings hosted the common seabird tick Ixodes uriae. This is a new host record for this species of tick. Ixodes uriae were distributed nonrandomly on nestlings within and among sites. Soil substrate was thought to be an important factor influencing tick distribution. Nestlings with severe tick infestation had slower rates of wing growth, reached peak mass at older ages, and fledged with shorter wings at older ages than nestlings with fewer ticks. By remaining in the nest for longer periods, nestlings with severe tick infestation may have been compensating for the delay in wing development.

Zooplankton biomass, advection and production on the northern Gulf of Alaska shelf from simulations and field observations

2013 ◽  
Vol 128 ◽  
pp. 185-207 ◽  
Author(s):  
K.O. Coyle ◽  
G.A. Gibson ◽  
K. Hedstrom ◽  
A.J. Hermann ◽  
R.R. Hopcroft
Keyword(s):  
Gulf Of Alaska ◽  
Zooplankton Biomass ◽  
Field Observations

The first 7 years (1978–1985) of ice wedge growth, Illisarvik experimental drained lake site, western Arctic coast

1986 ◽  
Vol 23 (11) ◽  
pp. 1782-1795 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Growth Rates ◽  
Linear Expansion ◽  
Temperature Dependent ◽  
Frozen Ground ◽  
Ice Wedge ◽  
Western Arctic ◽  
Arctic Coast ◽  
Coefficient Of Linear Expansion ◽  
Lake Site ◽  
Crack Widths

A large lake, measuring 600 m × 300 m and with a depth of nearly 5 m, was artificially drained on 13 August 1978. Observations on the formation, width, and depth of thermal contraction cracks for the first 7 years show that the crack profiles and ice wedge growth rates differ markedly from those of old ice wedges reported in the literature. The first winter's cracks had box-like profiles, with surface widths to 10 cm and depths to 2.5 m. Some cracks continued to widen and deepen, once opened in early winter, and then narrowed or even closed completely in summer. Mean growth rates for the ice wedges for the first few years have been as much as 3.5 cm/year. Temperature gradients at the time of first cracking have been in the range of 10–15 °C/m. The growth rate of young ice wedges is site specific and temperature dependent, varying with factors such as the temperature gradient, vegetation, and snow cover, so an estimate of the age of an ice wedge from its width will usually be impossible. A study of crack widths indicates that the apparent coefficient of linear expansion of frozen ground may be several times that of ice. Upward cracking has been proven.

Temperature Dependent Morphology Transition of GaN Films

1999 ◽  
Vol 572 ◽  
Author(s):  
A. R. A. Zauner ◽  
F. K. De Theue ◽  
P. R. Hageman ◽  
W. J. P. Van ◽  
J. J. Schermer ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Temperature Dependence ◽  
Growth Rates ◽  
Temperature Dependent ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Morphology Transition ◽  
Temperature Range ◽  
Sapphire Substrates ◽  
Low Pressure Mocvd

ABSTRACTThe temperature dependence of the surface morphology of GaN epilayers was studied with AFM. The layers were grown by low pressure MOCVD on (0001) sapphire substrates in the temperature range of 980°C-1085°C. In this range the (0001) and {1101} faces completely determine the morphology of 1.5 μm thick Ga-faced GaN films. For specimens grown at 20 mbar and temperatures below 1035°C the {1101} faces dominate the surface, which results in matt-white layers. At higher growth temperatures the morphology is completely determined by (0001) faces, which lead to smooth and transparent samples. For growth at 50 mbar, this transition takes place between 1000°C and 1015°C. It is shown that the morphology of the films can be described using a parameter αGaN, which is proportional to the relative growth rates of the (0001) and the {1101} faces.

scholarly journals Introduced mammals, vegetation changes and seabird conservation on the Scott Islands, British Columbia, Canada

2010 ◽  
Vol 20 (3) ◽  
pp. 295-305 ◽  
Author(s):  
J. MARK HIPFNER ◽  
MOIRA J. F. LEMON ◽  
MICHAEL S. RODWAY
Keyword(s):  
British Columbia ◽  
American Mink ◽  
Breeding Population ◽  
Vegetation Changes ◽  
Population Declines ◽  
Seabird Conservation ◽  
Time Period ◽  
Cassin's Auklet ◽  
Vegetation Surveys ◽  
Ptychoramphus Aleuticus

SummaryThe Scott Islands, British Columbia, Canada, support the largest aggregation of breeding seabirds in the eastern Pacific Ocean south of Alaska. However, large seabird populations were eradicated by American Mink Neovison vison and Raccoons Procyon lotor introduced to Lanz and Cox islands in the 1930s, while the ecological consequences of the introduction of European Rabbits Oryctolagus cuniculus to Triangle Island in the 1920s are unknown. We have seen dramatic changes in the vegetation on Triangle Island in recent decades, chiefly a decrease in Tufted Hairgrass Deschampsia cespitosa cover and a concomitant increase in Salmonberry Rubus spectabilis cover. We carried out vegetation surveys at Triangle Island (1989 and 2004) and its nearest neighbour, rabbit-free Sartine Island (1987 and 2006), to test the hypothesis that rabbits have caused these changes. We found, however, that similar changes have occurred at Sartine Island as at Triangle Island over the same time period. Because these two islands support the bulk of the world's breeding population of Cassin's Auklet Ptychoramphus aleuticus, a small seabird that selects grass-covered habitat but avoids tall Salmonberry for nesting, the vegetation changes raise serious concerns for a species that has experienced dramatic population declines in recent years. Restoration of seabird nesting habitat by removing American Mink and Raccoons from Lanz and Cox islands will be vital for long-term seabird conservation in the Scott Islands.

Temperature-Dependent Growth and Production by a Marine Copepod

1981 ◽  
Vol 38 (1) ◽  
pp. 77-83 ◽  
Author(s):  
I. A. McLaren ◽  
C. J. Corkett
Keyword(s):  
Growth Rates ◽  
Life Cycles ◽  
Temperature Dependent ◽  
Marine Copepod ◽  
Development Times ◽  
Body Sizes ◽  
Eurytemora Herdmani ◽  
Growth Production ◽  
Dependent Growth ◽  
Specific Growth Rates

Highly synchronous cohorts of the copepod Eurytemora herdmani at a station near Halifax, Nova Scotia, were followed in samples taken during late July and early August, 1980. Individuals from the same population were reared in the laboratory from copepodite I (CI) to adult in conditions of food satiation. Development times and adult body sizes in nature were about the same as predicted for comparable temperatures in the laboratory. Weight increments between CI and adult male in samples from nature were exponential. Females became heavier, because of eggs, after CIII, but developed more slowly, so that their specific growth rates were about the same as for males. Production estimated from weights and stage increments in successive samples (cohort method) was adequately predicted from biomasses in samples and temperature-dependent development times from the laboratory. Production of egg matter by adult females was also adequately predicted by temperature-dependent growth rates of younger stages. These "rules" of development, growth, and production need wider empirical testing and theoretical justification.Key words: Copepoda, temperature, life cycles, development, growth, production

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