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Michael L. Carroll

Bio: Michael L. Carroll is an academic researcher from University of Tromsø. The author has contributed to research in topics: Arctic & Benthic zone. The author has an hindex of 32, co-authored 64 publications receiving 3371 citations. Previous affiliations of Michael L. Carroll include University of Alaska Fairbanks & International Atomic Energy Agency.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors describe and quantify the key ecosystem components and basic food web structure of the Barents Sea, focusing on the energy flow through the ecosystem from an end-to-end perspective.

398 citations

Journal ArticleDOI
TL;DR: In this article, stable carbon (δ13C and nitrogen isotopes in a two-source food web model were used to determine trophic levels and the relative importance of open water and ice-associated food sources (phytoplankton vs ice algae) in the lower marine food web in the European Arctic during four seasons.

253 citations

Journal ArticleDOI
TL;DR: In this article, an empirical calibration of the carbonate clumped isotope thermometer based on mollusk and brachiopod shells from natural and controlled environments spanning water temperatures of −1.0 to 29.5°C is presented.

228 citations

Journal ArticleDOI
TL;DR: The results suggest recovery of sites by periodic abandonment (or fallowing) is one of the best management tools for sustainable salmon farming in cold-water environments.

223 citations

Journal ArticleDOI
TL;DR: This study demonstrates that ice algae are readily consumed and assimilated by the Arctic benthos, and may be prefer- entially selected by some benthic species (i.e. deposit feed- ers) due to their elevated EFA content, thus serving as an important component of the Arcticbenthic food web.
Abstract: We assessed the digestibility and utilization of ice algae and phytoplankton by the shallow, subtidal ben- thos in Ny Alesund (Kongsfjord) on Svalbard (79° N, 12° E) using chlorophyll a (chl a), essential fatty acids (EFAs) and stable isotopes as tracers of food consumption and assimi- lation Intact benthic communities in sediment cores and individuals of dominant benthic taxa were given ice algae, phytoplankton, 13 C-enriched ice algae or a no food addi- tion control for 19 to 32 d Ice algae and phytoplankton had significantly different isotopic signatures and relative con- centrations of fatty acids In the food addition cores, sedi- ment concentrations of chl a and the EFA C20:5(n-3) were elevated by 80 and 93%, respectively, compared to the control after 12 h, but decreased to background levels by 19 d, suggesting that both ice algae and phytoplankton were rapidly consumed Whole core respiration rates in the ice algae treatments were 14 times greater than in the other treatments within 12 h of food addition In the ice algae treatment, both suspension and deposit feeding taxa from 3 different phyla (Mollusca, Annelida and Sipuncula) exhibited significant enrichment in δ13 C values compared to the control Deposit feeders (15% uptake), however, ex- hibited significantly greater uptake of the 13 C-enriched ice algae tracer than suspension feeders (3% uptake) Our study demonstrates that ice algae are readily consumed and assimilated by the Arctic benthos, and may be prefer- entially selected by some benthic species (ie deposit feed- ers) due to their elevated EFA content, thus serving as an important component of the Arctic benthic food web

195 citations


Cited by
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01 Jan 1980
TL;DR: In this article, the influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition and found that the variability of the relationship between the δ^(15)N values of animals and their diets is greater for different individuals raised on the same diet than for the same species raised on different diets.
Abstract: The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

5,548 citations

30 Apr 1984
TL;DR: A review of the literature on optimal foraging can be found in this article, with a focus on the theoretical developments and the data that permit tests of the predictions, and the authors conclude that the simple models so far formulated are supported by available data and that they are optimistic about the value both now and in the future.
Abstract: Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

2,709 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed evidence of how climate change has already resulted in clearly discernable changes in marine Arctic ecosystems and found a total of 51 reports of documented changes in Arctic marine biota in response to climate change.
Abstract: In this article, we review evidence of how climate change has already resulted in clearly discernable changes in marine Arctic ecosystems. After defining the term ‘footprint’ and evaluating the availability of reliable baseline information we review the published literature to synthesize the footprints of climate change impacts in marine Arctic ecosystems reported as of mid-2009. We found a total of 51 reports of documented changes in Arctic marine biota in response to climate change. Among the responses evaluated were range shifts and changes in abundance, growth/condition, behaviour/phenology and community/regime shifts. Most reports concerned marine mammals, particularly polar bears, and fish. The number of well-documented changes in planktonic and benthic systems was surprisingly low. Evident losses of endemic species in the Arctic Ocean, and in ice algae production and associated community remained difficult to evaluate due to the lack of quantitative reports of its abundance and distribution. Very few footprints of climate change were reported in the literature from regions such as the wide Siberian shelf and the central Arctic Ocean due to the limited research effort made in these ecosystems. Despite the alarming nature of warming and its strong potential effects in the Arctic Ocean the research effort evaluating the impacts of climate change in this region is rather limited.

593 citations

Journal ArticleDOI
TL;DR: The biological pump is the process by which photosynthetically-produced organic matter in the ocean descends from the surface layer to depth by a combination of sinking particles, advection or vertical mixing of dissolved organic matter, and transport by animals as mentioned in this paper.

578 citations

Journal ArticleDOI
TL;DR: In this paper, the authors focus on ecosystem dynamics in the northern Bering and Chukchi Seas, with a more limited discussion of the adjoining Pacific-influenced eastern section of the East Siberian Sea and the western part of the Beaufort Sea.

573 citations