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.

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.

How ‘Best’ to Determine Trophic Levels in Archaeological Agricultural Communities

2017 ◽  
Author(s):  
Linda Reynard
Keyword(s):  
Stable Isotope ◽  
Trophic Level ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Trophic Levels ◽  
Bone Collagen ◽  
Carbon And Nitrogen ◽  
Agricultural Communities ◽  
Plant Remains ◽  
Isotope System

Stable isotope ratios of bone collagen have been used to determine trophic levels in diverse archaeological populations. The longest established and arguably most successful isotope system has been nitrogen, followed by carbon, and more recently hydrogen. These trophic level proxies rely on a predictable change in isotope ratio with each trophic level step; however, this requirement may not always be met, which can lead to difficulties in interpreting archaeological evidence. In agricultural communities, in particular, there are several possible complications to the interpretation of nitrogen and carbon isotopes. Recent approaches to overcome these limitations include better quantification and understanding of the influences on consumer isotope ratios; inclusion of evidence from plant remains; further investigation of apatite δ13C—collagen δ13C spacing in bones; measurement of carbon and nitrogen isotope ratios in individual amino acids, rather than collagen; and development of other stable isotope proxies for trophic level, such as hydrogen isotopes.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Stable Isotope ◽  
Pacific Ocean ◽  
Food Webs ◽  
Trophic Position ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Gulf Of Alaska ◽  
The North ◽  
Northeastern Pacific ◽  
The Mean

Abstract.—Spiny dogfish <em>Squalus acanthias </em>biomass has increased in the Gulf of Alaska, yet little is known about the ecological niche that dogfish fill in this ecosystem. Trophic position is an important indicator of the ecological role of an organism. To explore the trophic position of dogfish we analyzed the nitrogen and carbon stable isotope ratios of 60 dogfish from five locations between Washington and the Gulf of Alaska. The mean δ<sup>15</sup>N values for dogfish ranged from 12.0‰ (central Gulf of Alaska) to 13.4‰ (Howe Sound, British Columbia) and the mean δ<sup>13</sup>C values ranged from –21.3‰ (Yakutat Bay, Alaska) to –17.9‰ (Puget Sound, Washington). Sites to the north tended to be significantly depleted in the heavy isotopes of both nitrogen and carbon. The differences in nitrogen isotope ratios among sites were attributed to potential changes in dogfish feeding behavior and trophic position. Differences in carbon isotope ratios suggested that dogfish utilize different food webs along the northeastern Pacific Ocean shelf. Additionally it was hypothesized that feeding differentially in offshore versus inshore food webs or targeting pelagic versus benthic prey species may explain the isotopic variability. These results are preliminary and require additional tests before conclusions can be made about the trophic position of dogfish in this region. Future work will explore stable isotope variability at lower trophic levels to test the hypothesis that entire food webs are isotopically shifted owing to differences in isotopic fractionation at the base of the food web. Also, trophic level differences among dogfish size classes and between sexes will be explored among a greater diversity of locations to better describe the ecological consequences of increased biomass of dogfish in the northeastern Pacific Ocean.

scholarly journals The silicon stable isotope distribution along the GEOVIDE section (GEOTRACES GA-01) of the North Atlantic Ocean

2018 ◽  
Vol 15 (18) ◽  
pp. 5663-5676 ◽  
Author(s):  
Jill N. Sutton ◽  
Gregory F. de Souza ◽  
Maribel I. García-Ibáñez ◽  
Christina L. De La Rocha
Keyword(s):  
Stable Isotope ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Ocean ◽  
Water Masses ◽  
Labrador Sea ◽  
The North ◽  
The North Atlantic ◽  
Eastern North Atlantic

Abstract. The stable isotope composition of dissolved silicon in seawater (δ30SiDSi) was examined at 10 stations along the GEOVIDE section (GEOTRACES GA-01), spanning the North Atlantic Ocean (40–60∘ N) and Labrador Sea. Variations in δ30SiDSi below 500 m were closely tied to the distribution of water masses. Higher δ30SiDSi values are associated with intermediate and deep water masses of northern Atlantic or Arctic Ocean origin, whilst lower δ30SiDSi values are associated with DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly, the lowest δ30SiDSi values were observed in the deep and abyssal eastern North Atlantic, where dense southern-sourced waters dominate. The extent to which the spreading of water masses influences the δ30SiDSi distribution is marked clearly by Labrador Sea Water (LSW), whose high δ30SiDSi signature is visible not only within its region of formation within the Labrador and Irminger seas, but also throughout the mid-depth western and eastern North Atlantic Ocean. Both δ30SiDSi and hydrographic parameters document the circulation of LSW into the eastern North Atlantic, where it overlies southern-sourced Lower Deep Water. The GEOVIDE δ30SiDSi distribution thus provides a clear view of the direct interaction between subpolar/polar water masses of northern and southern origin, and allow examination of the extent to which these far-field signals influence the local δ30SiDSi distribution.

The diet of amphioxus in subtropical Hong Kong as indicated by fatty acid and stable isotopic analyses

2008 ◽  
Vol 88 (7) ◽  
pp. 1487-1491 ◽  
Author(s):  
Y. Chen ◽  
S.G. Cheung ◽  
P.K.S. Shin
Keyword(s):  
Hong Kong ◽  
Fatty Acid ◽  
Stable Isotope ◽  
Trophic Levels ◽  
Food Sources ◽  
Filter Feeder ◽  
Total Particulate Matter ◽  
Isotopic Analyses ◽  
Wide Range ◽  
Hong Kong Waters

Fatty acid profiles and carbon (δ13C) and nitrogen (δ15N) stable isotope markers were used to identify the diet of amphioxus in subtropical Hong Kong waters, and to evaluate the role of co-occurring Branchiostoma belcheri and B. malayanum in trophic transfer, in coastal ecosystems. The present results showed that while amphioxus is generally regarded as a filter feeder, total particulate matter in the water column might not be the main food supply. The diet of amphioxus could be traced to comprise a wide range of food sources, from microbes and microplankton to microalgae, based on the stable isotope analysis. Results of fatty acid profile analysis also revealed contributions from dinoflagellates, zooplankton, detritus and bacteria, and minor contribution from diatoms and fungi in the diet of amphioxus in Hong Kong waters. The use of fatty acid and stable isotope analyses further proved that amphioxus can, not only capture and partition such a different size-range of food particles during their feeding, but also assimilate most of them into their body tissue. The present findings suggested that amphioxus may play an important role in marine food webs by transferring microbial production to higher trophic levels through utilizing microbes in seawater as food.

scholarly journals Trophic interactions of meso- and macrozooplankton and fish in the Iceland Sea as evaluated by fatty acid and stable isotope analysis

2012 ◽  
Vol 69 (7) ◽  
pp. 1277-1288 ◽  
Author(s):  
Hildur Petursdottir ◽  
Stig Falk-Petersen ◽  
Astthor Gislason
Keyword(s):  
Fatty Acid ◽  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Trophic Interactions ◽  
Trophic Ecology ◽  
Feeding Habits ◽  
Isotope Analysis ◽  
Trophic Levels ◽  
Amphipod Species ◽  
Blue Whiting

Abstract Petursdottir, H., Falk-Petersen, S., and Gislason, A. 2012. Trophic interactions of meso- and macrozooplankton and fish in the Iceland Sea as evaluated by fatty acid and stable isotope analysis. – ICES Journal of Marine Science, 69: . A trophic study was carried out in August of 2007 and 2008 on the pelagic ecosystem in the Subarctic Iceland Sea. Carbon and nitrogen stable isotopes and fatty acid biomarkers were used to study trophic linkages and the trophic ecology of the most important pelagic species in this ecosystem, with emphasis on capelin (Mallotus villosus). According to 15N enrichment results, there are 3–4 trophic levels in this ecosystem excluding organisms of the microbial loop and birds and mammals. The primarily herbivorous copepod Calanus hyperboreus occupies the lowest trophic level of the animal species studied, and adult capelin and blue whiting (Micromesistius poutassou) occupy the highest level. Calanus spp. proved to be an important dietary component of most of the species studied, the euphausiid species Thysanoessa inermis and T. longicaudata being exceptions. The chaetognath Eukrohnia hamata is a pure carnivore, feeding heavily on Calanus spp., whereas most of the other zooplankton species studied practice an omnivorous–carnivorous feeding mode. The amphipod species Themisto libellula is important in the diet of adult capelin. Adult capelin and blue whiting share the same feeding habits and could therefore be competing for food.

Flexible diet and trophic position of dreissenid mussels as inferred from stable isotopes of carbon and nitrogen

2005 ◽  
Vol 62 (5) ◽  
pp. 1119-1129 ◽  
Author(s):  
David W Garton ◽  
Christopher D Payne ◽  
Joseph P Montoya
Keyword(s):  
Stable Isotope ◽  
Dreissena Polymorpha ◽  
Lake Erie ◽  
Trophic Position ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Trophic Levels ◽  
Food Sources ◽  
Stable Isotope Ratios ◽  
Western Lake

In this study, the trophic position and food-web impacts of invading zebra mussels (Dreissena polymorpha) were investigated by sampling mussels, seston (= phytoplankton), macrophytes, zooplankton, and surficial sediment in two small inland lakes (1999–2002) and similarly in western Lake Erie (1999 only). Tissues from quagga mussels (Dreissena bugensis) from Lake Erie were also analyzed. Stable-isotope ratios (15N/14N and 13C/12C) were used to identify likely food sources and estimate relative trophic position. For Lake Erie, stable-isotope ratios indicated no diet differences between the two mussel species. For all lakes, zooplankton δ13C was indicative of phytoplanktivory. The 13C stable isotope ratios indicated that seston comprised ~50% of food sources for mussels in Lake Erie, but 73%–97% and 52%–100% of the diet of mussel populations in Lake Wawasee and Clark Lake, respectively. Stable nitrogen isotope ratios placed zooplankton at trophic levels equal to or higher than those of mussels in seven of eight comparisons. Dreissena polymorpha and D. bugensis are able to exploit suspended detritus as a significant energy source, as well as compete directly with zooplankton for seston as a food source and with each other in areas of sympatry.

scholarly journals First indications that northern bottlenose whales are sensitive to behavioural disturbance from anthropogenic noise

2015 ◽  
Vol 2 (6) ◽  
pp. 140484 ◽  
Author(s):  
P. J. O. Miller ◽  
P. H. Kvadsheim ◽  
F. P. A. Lam ◽  
P. L. Tyack ◽  
C. Curé ◽  
...  
Keyword(s):  
North Atlantic ◽  
Animal Movement ◽  
North Atlantic Ocean ◽  
Natural Habitat ◽  
High Sensitivity ◽  
Anthropogenic Noise ◽  
The North ◽  
Beaked Whales ◽  
Movement Parameters ◽  
Northern Bottlenose Whales

Although northern bottlenose whales were the most heavily hunted beaked whale, we have little information about this species in its remote habitat of the North Atlantic Ocean. Underwater anthropogenic noise and disruption of their natural habitat may be major threats, given the sensitivity of other beaked whales to such noise disturbance. We attached dataloggers to 13 northern bottlenose whales and compared their natural sounds and movements to those of one individual exposed to escalating levels of 1–2 kHz upsweep naval sonar signals. At a received sound pressure level (SPL) of 98 dB re 1 μPa, the whale turned to approach the sound source, but at a received SPL of 107 dB re 1 μPa, the whale began moving in an unusually straight course and then made a near 180° turn away from the source, and performed the longest and deepest dive (94 min, 2339 m) recorded for this species. Animal movement parameters differed significantly from baseline for more than 7 h until the tag fell off 33–36 km away. No clicks were emitted during the response period, indicating cessation of normal echolocation-based foraging. A sharp decline in both acoustic and visual detections of conspecifics after exposure suggests other whales in the area responded similarly. Though more data are needed, our results indicate high sensitivity of this species to acoustic disturbance, with consequent risk from marine industrialization and naval activity.

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