Intrinsic and extrinsic sources of variation in the diets of harp and hooded seals revealed by fatty acid profiles

2009 ◽  
Vol 87 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Strahan Tucker ◽  
W. Don Bowen ◽  
Sara J. Iverson ◽  
Garry B. Stenson
Keyword(s):  
Fatty Acid ◽  
North Atlantic Ocean ◽  
Geographic Location ◽  
Deep Ocean ◽  
Resource Polymorphism ◽  
The North ◽  
Pagophilus Groenlandicus ◽  
Ontogenetic Niche Shifts ◽  
Significant Difference ◽  
Sources Of Variation

Individuals of different age, sex, and morphology are expected to exhibit differences in dietary niches largely owing to sexual dimorphism, ontogenetic niche shifts, and resource polymorphism. Harp ( Pagophilus groenlandicus (Erxleben, 1777)) and hooded ( Cystophora cristata (Erxleben, 1777)) seals are geographically overlapping and highly migratory predators in the North Atlantic Ocean. These species differ in their diving behaviour, with hooded seals diving deeper, longer, and more associated with the continental shelf edge and deep ocean than harp seals. We examined blubber fatty acid (FA) composition (N = 37; 93% of total FA by mass) of harp (adults N = 294; juveniles N = 232) and hooded (adults N = 118; juveniles N = 38) seals to test hypotheses about sources of intrinsic (age and sex) and extrinsic (geographic location, season, year) variations in diets. A significant difference in FA profiles suggested dietary segregation between species. We found significant effects of sex and age class on FA profiles, with these being more pronounced in the highly size-dimorphic hooded seals than in harp seals. FA profiles of both species also varied between inshore and offshore sampling locations and between prebreeding and postbreeding periods. Finally, FA profiles of harp seals differed among years, which was coincident with large changes in prey distribution and availability in the mid-1990s.

An investigation of storm waves in the North Atlantic Ocean

1955 ◽  
Vol 230 (1183) ◽  
pp. 560-569 ◽  
Keyword(s):  
Wind Speed ◽  
Shallow Water ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Deep Ocean ◽  
The North ◽  
Storm Waves ◽  
The Difference ◽  
Tidal Streams ◽  
Wave Recorder

Since February 1953 the Ocean Weather Ship Weather Explorer , using a shipborne wave recorder, has taken records of waves at the positions ‘India’ (61° 00' N, 15° 20' W) and ‘Juliet’ (52° 20' N, 20° 00'W). An investigation of the records shows that conditions of wave generation in the deep ocean are different from those on the continental shelf. In both deep and shallow water, the steepness of the highest waves decreases as the fetch increases until an equilibrium value is reached after about 100 miles. In deep water this equilibrium value increases with the wind speed, whereas in shallow water it tends to decrease with wind speed. Different empirical rules are required for wave prediction in the deep ocean and the shallow sea. The difference can probably be attributed to a greater effect of turbulence near the coast, where the depth is of the same order as the wavelength and there are active tidal streams.

Phytoplankton Biogeochemical Cycles

2017 ◽  
Author(s):  
Carol Robinson
Keyword(s):  
Inorganic Carbon ◽  
North Atlantic Ocean ◽  
Dissolved Inorganic Carbon ◽  
Deep Ocean ◽  
Biogeochemical Cycles ◽  
Essential Elements ◽  
Nitrogen And Phosphorus ◽  
The North ◽  
Life On Earth ◽  
Fish And Shellfish

This chapter describes how the activity of phytoplankton, bacteria, and Archaea drive the marine biogeochemical cycles of carbon, nitrogen, and phosphorus, and how climate driven changes in plankton abundance and community composition influence these biogeochemical cycles in the North Atlantic Ocean and adjacent seas. Carbon, nitrogen, and phosphorus are essential elements required for all life on Earth. In the marine environment, dissolved inorganic carbon, nitrogen, and phosphorus are utilized during phytoplankton growth to form organic material, which is respired and remineralized back to inorganic forms by the activity of bacteria, Archaea, and zooplankton. The net result of the photosynthesis, calcification, and respiration of marine plankton is the uptake of carbon dioxide from the atmosphere, its sequestration to the deep ocean as organic and inorganic carbon, and its availability to fuel all fish and shellfish production.

Counting Harp Seals with ultra-violet photography

Polar Record ◽  
1976 ◽  
Vol 18 (114) ◽  
pp. 269-277 ◽  
Author(s):  
D. M. Lavigne
Keyword(s):  
North Atlantic ◽  
White Sea ◽  
North Atlantic Ocean ◽  
Ultra Violet ◽  
The Arctic ◽  
Hudson Bay ◽  
The North ◽  
Breeding Populations ◽  
Pagophilus Groenlandicus ◽  
Arctic Ice

The Harp Seal Pagophilus groenlandicus is a gregarious, migratory seal inhabiting Arctic and sub-Arctic waters of the North Atlantic Ocean. In spring, asthe ice recedes, the largest of three known breeding populations migrates up the east coas of Canada from the Gulf of St Lawrence, along the coast of Labrador, to the Canadian Archipelago, Hudson Bay, and the west coast of Greenland. After spending the summer feeding in Arctic waters, the seals move southward ahead of the Arctic ice pack, reaching the coast of Labrador and the Gulf of St Lawrence sometime in late December or early January. They reappear at the end of February and in early March in whelping ‘patches’ or concentrations on ice inthe Gulf of St Lawrence west of the Magdalen Islands, and off the coast of Labrador in an areaknown as the ‘Front’. One of the two smaller and probably distinct breeding populations is to be found in the White Sea, the other in the Vestisen [West Ice] between Jan Mayen and Svalbard.

scholarly journals The sources of deep ocean infragravity waves observed in the North Atlantic Ocean

2015 ◽  
Vol 120 (7) ◽  
pp. 5120-5133 ◽  
Author(s):  
Wayne Crawford ◽  
Valerie Ballu ◽  
Xavier Bertin ◽  
Mikhail Karpytchev
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Deep Ocean ◽  
Infragravity Waves ◽  
The North ◽  
The North Atlantic

Eulerian and Lagrangian Velocity Distributions in the North Atlantic

2005 ◽  
Vol 35 (12) ◽  
pp. 2327-2336 ◽  
Author(s):  
J. H. LaCasce
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Deep Ocean ◽  
The North ◽  
Lagrangian Velocity ◽  
Velocity Probability ◽  
Using Data ◽  
Subsurface Current ◽  
Non Gaussian ◽  
Main Thermocline

Abstract Velocity probability density functions (PDFs) are calculated using data from subsurface current meters in the western North Atlantic Ocean. The PDFs are weakly, but significantly, non-Gaussian. They deviate from normality because of an excess of energetic events, and there are evidently more such events in the main thermocline than in the deep ocean. The PDFs are also compared with those obtained from subsurface floats in the same region. The PDFs are statistically indistinguishable so long as the float data are averaged in appropriately sized bins. Taking too-small bins yields overly Gaussian float PDFs, and taking too-large bins yields too-non-Gaussian PDFs. With this caveat, the Lagrangian and Eulerian PDFs agree, consistent with expectations from theory and previous numerical simulations.

scholarly journals The Influence of Ocean Convection Patterns on High-Latitude Climate Projections

2004 ◽  
Vol 17 (22) ◽  
pp. 4316-4329 ◽  
Author(s):  
M. Schaeffer ◽  
F. M. Selten ◽  
J. D. Opsteegh ◽  
H. Goosse
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Surface Air Temperature ◽  
Deep Ocean ◽  
Ocean Model ◽  
Climate Projections ◽  
The North ◽  
The North Atlantic ◽  
Convection Patterns

Abstract The mean state and variability of deep convection in the ocean influence the North Atlantic climate. Using an ensemble experiment with a coupled atmosphere–ocean–sea ice model, it is shown that cooling and subdued warming areas can occur over the North Atlantic Ocean and adjacent landmasses under global warming. Different “present-day” convection patterns in the Greenland–Iceland–Norway (GIN) Sea result in different future surface-air temperature changes. At higher latitudes, the more effective positive sea ice feedback increases the likelihood of changes in convection causing a regional cooling that is larger than the warming brought about by the enhanced greenhouse effect. The modeled freshening of deep ocean layers in the North Atlantic in a time period preceding a reorganization of GIN Sea convection is consistent with recent observations. Low-frequency internal variability in the ocean model has relatively little impact on the response patterns.

Diet of northern bottlenose whales inferred from fatty-acid and stable-isotope analyses of biopsy samples

2001 ◽  
Vol 79 (8) ◽  
pp. 1442-1454 ◽  
Author(s):  
Sascha K Hooker ◽  
Sara J Iverson ◽  
Peggy Ostrom ◽  
Sean C Smith
Keyword(s):  
Fatty Acid ◽  
Stable Isotope ◽  
Marine Protected Area ◽  
North Atlantic Ocean ◽  
Submarine Canyon ◽  
Nitrogen Isotope ◽  
Trophic Levels ◽  
Eastern Canada ◽  
The North ◽  
Northern Bottlenose Whales

The Gully submarine canyon off eastern Canada has been designated a pilot marine protected area largely because of the northern bottlenose whales (Hyperoodon ampullatus) found there. Studies of this species' diet elsewhere in the North Atlantic Ocean have suggested specialization on the deep-sea squid Gonatus fabricii. We found a high proportion of the congener Gonatus steenstrupi in the stomachs of two bottlenose whales stranded in eastern Canada. In 1997, we collected remote biopsy samples from free-ranging bottlenose whales off Nova Scotia; fatty acids were determined from blubber samples and stable isotopes (carbon and nitrogen) from skin samples. Although fatty-acid stratification throughout the depth of the blubber layer was present (determined from blubber samples of stranded animals), the magnitude of stratification was less pronounced than in many other cetaceans, allowing some qualitative inferences to be made from shallow biopsy samples. Fatty-acid patterns and stable-isotope values from whales were compared with those in samples of G. fabricii from the Norwegian Sea. Blubber fatty acid composition was similar in characteristics to that of adult G. fabricii but was markedly distinct from that of juvenile G. fabricii and other recorded prey species. Nitrogen-isotope values implied that bottlenose whales (mean 15.3‰) and adult G. fabricii (mean 13.7‰) occupy high trophic levels. Overall, the results of these techniques concurred in suggesting that squid of the genus Gonatus may form a major part of the diet of bottlenose whales in the Gully.

scholarly journals The origin of deep ocean microseisms in the North Atlantic Ocean

2008 ◽  
Vol 464 (2091) ◽  
pp. 777-793 ◽  
Author(s):  
Sharon Kedar ◽  
Michael Longuet-Higgins ◽  
Frank Webb ◽  
Nicholas Graham ◽  
Robert Clayton ◽  
...  
Keyword(s):  
North America ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Deep Ocean ◽  
Ocean Waves ◽  
Ocean Wave ◽  
Pressure Oscillations ◽  
The North ◽  
The North Atlantic

Oceanic microseisms are small oscillations of the ground, in the frequency range of 0.05–0.3 Hz, associated with the occurrence of energetic ocean waves of half the corresponding frequency. In 1950, Longuet-Higgins suggested in a landmark theoretical paper that (i) microseisms originate from surface pressure oscillations caused by the interaction between oppositely travelling components with the same frequency in the ocean wave spectrum, (ii) these pressure oscillations generate seismic Stoneley waves on the ocean bottom, and (iii) when the ocean depth is comparable with the acoustic wavelength in water, compressibility must be considered. The efficiency of microseism generation thus depends on both the wave frequency and the depth of water. While the theory provided an estimate of the magnitude of the corresponding microseisms in a compressible ocean, its predictions of microseism amplitude heretofore have never been tested quantitatively. In this paper, we show a strong agreement between observed microseism and calculated amplitudes obtained by applying Longuet-Higgins' theory to hindcast ocean wave spectra from the North Atlantic Ocean. The calculated vertical displacements are compared with seismic data collected at stations in North America, Greenland, Iceland and Europe. This modelling identifies a particularly energetic source area stretching from the Labrador Sea to south of Iceland, where wind patterns are especially conducive to generating oppositely travelling waves of same period, and the ocean depth is favourable for efficient microseism generation through the ‘organ pipe’ resonance of the compression waves, as predicted by the theory. This correspondence between observations and the model predictions demonstrates that deep ocean nonlinear wave–wave interactions are sufficiently energetic to account for much of the observed seismic amplitudes in North America, Greenland and Iceland.

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