DOCSLIB.ORG

Stable Isotope Diagrams of Freshwater Food Webs

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Stable Isotope Diagrams of Freshwater Food Webs NOTES AND COMMENTS 2293 i.e., m, = d,ls,, where d, is the number of deaths during mortality rates, which have been described above, are the time interval i, and s, is the number of survivors approaches that can enable very short periods of time at the midpoint of the time interval i. to be identified when mortality risks differ substantially Gehan ( 1969) has derived an equation which enables between sets of plants. Although for the field ecologist the variance of the midpoint age-specific mortality to inferences about the causes of plant death will always be determined: be easier than proof, the ability to compare mortality rates over very short time intervals will allow more accurate interpretation of the causes of mortality and Var[m,] = (:/ {1 - ( ~')l promote a sharper understanding of the tolerance lim­ its of species in the field. d, . where q, = -, I.e., s, Acknowledgments: This work was undertaken while K. D. Booth was in receipt of a Science and Engineering 2 , (m,)' 2 {. ( m,' ) } Research Council studentship. We gratefully acknowl­ Var[m,] = T 1 - . 2 edge the helpful comments of four referees, including David Pyke and Dolph Schluter. This formula may be used to calculate 95% confidence intervals around m, values (Fig. 1), aiding the com­ Literature Cited parison of survivorship patterns in the cohorts (Lee Gehan, E. A. 1969. Estimating survival functions from the 1980). When this procedure is applied to the data of life table. Journal of Chronic Diseases 21:629-644. Pyke and Thompson ( 1986), the analysis shows that Lee, E. T. 1980. Statistical methods for survival data anal­ the mortality rates differ significantly in the two cohorts ysis. Lifetime Learning Publications, Belmont, California, during the intervals between days 0-10, 10-20, 30-40, USA. Mantel, N., and W. Haenszel. 1959. Statistical aspects of and 50-60, confirming the conclusions of the analysis the analysis of data from retrospective studies of disease. of the residuals generated during calculation of the lo­ Journal ofthe National Cancer Institute 22:719-748. grank statistic. Muenchow, G. 1986. Ecological use of failure time analysis. Ecology 67:246-250. Conclusions Peto, R., and M. C. Pike. 1973. Conservatism of the ap­ proximation ~ (C - E) 2/E in the logrank test for survival Despite the vigor with which plant demography has data or tumor incidence data. Biometrics 29:579-584. been pursued in the last twenty years, ecologists are Pyke, D. A., and J. N. Thompson. 1986. Statistical analysis still mostly ignorant of the causes of the deaths of in­ of survival and removal rate experiments. Ecology 67:240- dividual plants in the field and of the reasons why 245. Pyke, D. A., and J. N. Thompson. 1987. Erratum. Ecology mortality rates of species differ between sites and dif­ 68:232. ferent growing conditions. Common problems in in­ Tremlett, M., J. W. Silvertown, and C. Tucker. 1984. An terpreting the causes of mortality and the rates of mor­ analysis of spatial and temporal variation in seedling sur­ tality in populations stem from our ignorance of the vival of a monocarpic perennial, Conium maculatum. Oi­ exact times at which plants have died and of variations kos 43:41-45. in mortality rates through time. The analysis of resid­ Manuscript received 16 January 1991; uals, and comparison of confidence intervals about revised 20 May 1991; accepted 21 May 1991. Ecology, 72(6), 1991, pp. 2293-2297 organic matter is cycled in different ecosystems. For © 1991 by the Ecological Society of America example, a few measurements of isotopic compositions of dissolved nutrients, aquatic plants, and animals es­ tablish a chemical outline of food web structure (Fry STABLE ISOTOPE DIAGRAMS OF and Sherr 1984, Minagawa and Wada 1984). These tracer results can be used to check conventional ideas FRESHWATER FOOD WEBS about trophic structure in well-studied systems, and to test how food web structure varies in other systems Brian Fry' where conventional visual studies of trophic relations are difficult or lacking (Rau 1980). A dual-isotope ap­ Stable carbon and nitrogen isotopes are valuable proach is often useful in these studies, for example, tracers in ecological research (Runde! et al. 1988). One with nitrogen isotope measurements functioning as tro­ use of isotope measurements is to rapidly survey how phic level indicators, and carbon isotope measure­ 1 The Ecosystems Center, Marine Biological Laboratory, ments indicating which plants are important sources Woods Hole, Massachusetts 02543 USA. of nutrition for consumers (Peterson and Fry 1987). 2294 NOTES AND COMMENTS Ecology, Vol. 72, No.6 Ecologists from Long Term Ecological Research ll 13C and ll'5N values are reported relative to carbon (LTER) sites in the United States and Puerto Rico in the Peedee belemnite (PDB) limestone and nitrogen recently used isotope analysis to test ideas about aquat­ in air, respectively, in parts per thousand (o/oo). ic food-web structure and terrestrial nitrogen cycling. This note reports an overview of the food-web results 1Jl3C or IJlSN = [Rsample - R,.andard] X 103, and discussed at a workshop in September 1989, and in­ Rstandard 5 cludes a ll' N survey of terrestrial materials that con­ R = 13C/' 2C or 15N/14N. tribute to freshwater food webs as allochthonous or­ ganic matter. A list of isotopic analyses from each site High-purity tank carbon dioxide and nitrogen gases is available.2 were used as working standards during sample analysis. These working standards had been calibrated against National Bureau of Standards (NBS) isotope standards Study Areas NBS-20 limestone and NBS-21 graphite for /l 13C, at­ Samples for studies offood webs were collected from mospheric nitrogen and N-1 ammonium sulfate for streams (sites I, 3, 8, and 17, Fig. 1) and lakes (sites ll'5N (Coplen et a!. 1983, Mariotti 1983, Minagawa et 1, 10, and 16). To determine generality of /l 15N values a!. 1984, Nevins et a!. 1985). PDB and nitrogen in air in plants and soils, samples were also collected at sev­ have by definition ll values of Oo/oo; samples enriched eral sites in forests (sites 2, 9, 12, 15, 16, and 17), in 13C or 15 N are "heavy" and have higher /l 13C and grasslands and deserts (sites 4, 5, and 7), at a coastal ll'5N values, while samples enriched in 12C and 14N dune site (site 14), and at a high-altitude tundra site have lower ll values. (site 6). Food Webs Methods Nitrogen isotopic compositions of plants and vari­ Soils, plant leaf material, plant litter, and whole an­ ous types of animal consumers showed remarkable imals or muscle tissue from fish were collected in the similarity in eight lake and stream sites sampled (Fig. 15 summer of 1989, dried at 60°C, and ground to fine 2). Plants had lowest ll N values of typically -4 to 5 powders. Most samples were composites of > 5 indi­ + 3o/oo, and ll' N values of aquatic and terrestrial plants vidual samples. Samples were combusted at 750°C were generally similar (Fig. 2). A broad analysis of 15 overnight (soils) or 900°C for 1 h (plants, animals) in plants and soil fractions showed that ll N values of evacuated sealed Vycor high temperature glass tubes terrestrial materials at the lake and stream sites were (Corning Glass, Corning, New York) containing 1 g of fairly typical and could be expected to occur at most CuO and 0.5 g Cu metal (Minagawa eta!. 1984). Sam­ other LTER sites where streams and lakes were often ple sizes were typically 5 mg for animals, 15 mg for present, but not sampled (Figs. 2 and 3). Plants and plants, and 50-1000 mg for soils. To obtain accurate soils in these relatively undisturbed L TER sites also 15 ll'5N values, it was necessary to grind soils, but not had generally lower ll N values than previously ana­ plant or animal samples, with CuO prior to combus­ lyzed agricultural plants and soils of North America tion. (Feigin eta!. 1974, Shearer eta!. 1978). Only samples 15 Combustion gases were cryogenically separated and from arid sites 4 and 5 had higher average /l N values similar to those found in agricultural sites (Fig. 3). pure C02 and N 2 measured for carbon and nitrogen isotope values with a Finnigan 251 stable isotope ratio Animals from L TER lakes and streams had higher 5 15 mass spectrometer. Molecular sieve (0.5 nm, Alltech ll' N values than did plants, and animal /l N values Associates, Deerfield, Illinois) was used during collec­ increased with increasing trophic level (Fig. 2). There was an average ll'5N increase of2-3o/oo per trophic level tion and transfer of N 2 gas between vacuum prepara­ tion lines and the mass spectrometer. Replicates usu­ (Fig. 2), and at all sites top predators, such as small­ ally fell within a 0.2o/oo range for both carbon and mouth bass and giant salamanders, had highest values nitrogen isotope measurements; an increased range of­ (up to 9o/oo higher than algae at the base of the food 15 ten resulted if samples had not been finely ground to web). Using the assumption of a 3.3o/oo increase in /l N 15 a flour-like consistency. per trophic level (Minagawa and Wada 1984), the /l N results indicate that there are 2.5-3.5 trophic levels in all stream and lake ecosystems (Fig. 2). 2 See ESA Supplementary Publication Service Document The estimate of 2.5-3.5 trophic levels agrees fairly No. 9102 for 32 pages of supplementary material. This doc­ well with estimates of trophic complexity in other ument is available on microfiche or in printed form.
Load more

Recommended publications
  • Stable Isotope Methods in Biological and Ecological Studies of Arthropods
    eea_572.fm Page 3 Tuesday, June 12, 2007 4:17 PM DOI: 10.1111/j.1570-7458.2007.00572.x Blackwell Publishing Ltd MINI REVIEW Stable isotope methods in biological and ecological studies of arthropods CORE Rebecca Hood-Nowotny1* & Bart G. J. Knols1,2 Metadata, citation and similar papers at core.ac.uk Provided by Wageningen University & Research Publications 1International Atomic Energy Agency (IAEA), Agency’s Laboratories Seibersdorf, A-2444 Seibersdorf, Austria, 2Laboratory of Entomology, Wageningen University and Research Centre, P.O. Box 8031, 6700 EH Wageningen, The Netherlands Accepted: 13 February 2007 Key words: marking, labelling, enrichment, natural abundance, resource turnover, 13-carbon, 15-nitrogen, 18-oxygen, deuterium, mass spectrometry Abstract This is an eclectic review and analysis of contemporary and promising stable isotope methodologies to study the biology and ecology of arthropods. It is augmented with literature from other disciplines, indicative of the potential for knowledge transfer. It is demonstrated that stable isotopes can be used to understand fundamental processes in the biology and ecology of arthropods, which range from nutrition and resource allocation to dispersal, food-web structure, predation, etc. It is concluded that falling costs and reduced complexity of isotope analysis, besides the emergence of new analytical methods, are likely to improve access to isotope technology for arthropod studies still further. Stable isotopes pose no environmental threat and do not change the chemistry or biology of the target organism or system. These therefore represent ideal tracers for field and ecophysiological studies, thereby avoiding reductionist experimentation and encouraging more holistic approaches. Con- sidering (i) the ease with which insects and other arthropods can be marked, (ii) minimal impact of the label on their behaviour, physiology, and ecology, and (iii) environmental safety, we advocate more widespread application of stable isotope technology in arthropod studies and present a variety of potential uses.
    [Show full text]
  • Measurement of the Isotopic Composition of Dissolved Iron in the Open Ocean F
    Measurement of the isotopic composition of dissolved iron in the open ocean F. Lacan, Amandine Radic, Catherine Jeandel, Franck Poitrasson, Géraldine Sarthou, Catherine Pradoux, Remi Freydier To cite this version: F. Lacan, Amandine Radic, Catherine Jeandel, Franck Poitrasson, Géraldine Sarthou, et al.. Measure- ment of the isotopic composition of dissolved iron in the open ocean. Geophysical Research Letters, American Geophysical Union, 2008, pp.L24610. 10.1029/2008GL035841. hal-00399111 HAL Id: hal-00399111 https://hal.archives-ouvertes.fr/hal-00399111 Submitted on 15 Jul 2009 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 Measurement of the Isotopic Composition of dissolved Iron in the Open Ocean 2 3 Lacan1 F., Radic1 A., Jeandel1 C., Poitrasson2 F., Sarthou3 G., Pradoux1 C., Freydier2 R. 4 5 1: CNRS, LEGOS, UMR5566, CNRS-CNES-IRD-UPS, Observatoire Midi-Pyrénées, 18, Av. 6 E. Belin, 31400 Toulouse, France. 7 2: LMTG, CNRS-UPS-IRD, 14-16, avenue Edouard Belin, 31400 Toulouse, France. 8 3: LEMAR, UMR CNRS 6539, IUEM, Technopole Brest Iroise, Place Nicolas Copernic, 9 29280 Plouzané, France. 10 11 Paper published in Geophysical Research Letters (2008) L24610. 12 We acknowledge Geophysical Research Letters and the American Geophysical Union copyright 13 14 This work demonstrates for the first time the feasibility of the measurement of the isotopic 15 composition of dissolved iron in seawater for a typical open ocean Fe concentration range 16 (0.1-1nM).
    [Show full text]
  • Stable Isotope Analyses Differentiate Between Different Trophic Pathways Supporting Rocky-Reef Fishes
    MARINE ECOLOGY PROGRESS SERIES Vol. 95: 19-24, 1993 Published May 19 Mar. Ecol. Prog. Ser. Stable isotope analyses differentiate between different trophic pathways supporting rocky-reef fishes Carrie J. Thomas, Lawrence B. Cahoon Biological Sciences, University of North Carolina at Wilmington, Wilmington, North Carolina 28403, USA ABSTRACT: Stable isotope analyses of 5 reef-associated fishes, Decapterus punctatus. Diplodus holbrooki, Rhornboplites aurorubens. Pagrus pagrus, and Haernulon aurolineatum, were conducted to determine the ability of stable isotope analysis to distinguish among the species and the trophic pathways that support them. Analyses of F13C, 615~,and 634~from white swimming muscle yielded significant differences between species. Multiple stable isotope signatures of these 5 species indicated that at least 2 trophic pathways, one planktonic and one benthic, supported these reef-associated species. Variability of isotopic signatures within species was largely a result of collection site differ- ences. 8l3C and 615N values inchcated that all fishes were feeding at similar trophic levels. P4S values proved to be useful supplements to carbon and nitrogen isotope values in separating species by signature. INTRODUCTION sandy areas (Hales 1987, Donaldson 1991). Other fishes, such as Diplodus holbrooki (spottail pinfish), Total primary production on the continental shelf off feed upon benthic macroalgae and associated inverte- North Carolina, USA, is supported by 3 sources: phyto- brates (Hay & Sutherland 1988, Pike 1991). Finally, plankton, benthic macroalgae, and benthic micro- demersal zooplankton feed on benthic microalgae algae. Cahoon et al. (1990) found benthic microalgal (Tronzo 1989).Demersal zooplankton are in turn a food biomass frequently equalled or exceeded integrated item for fishes such as Haemulon aurolineatum phytoplankton biomass across the shelf.
    [Show full text]
  • Ocean Ecogeochemistry a Review
    Oceanography and Marine Biology: An Annual Review, 2013, 51, 327-374 © Roger N. Hughes, David Hughes, and I. Philip Smith, Editors Taylor & Francis OcEaN EcOgeochemistry: a review KElton w. mcmahon1,2,3, Li Ling HamaDy1 & SImon R. ThorrolD1 1Biology Department, Woods Hole Oceanographic Institution, MS50, Woods Hole, MA 02543, USA E- mail: [email protected] (corresponding author), [email protected] 2Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia E- mail: [email protected] 3Ocean Sciences Department, University of California-Santa Cruz, SantaCruz, CA 95064, USA animal movements and the acquisition and allocation of resources provide mechanisms for indi- vidual behavioural traits to propagate through population, community and ecosystem levels of biological organization. Recent developments in analytical geochemistry have provided ecolo- gists with new opportunities to examine movements and trophic dynamics and their subsequent influence on the structure and functioning of animal communities. we refer to this approach as ecogeochemistry—the application of geochemical techniques to fundamental questions in popula- tion and community ecology. we used meta- analyses of published data to construct δ2H, δ13c, δ15N, δ18O and Δ14c isoscapes throughout the world’s oceans. These maps reveal substantial spatial vari- ability in stable isotope values on regional and ocean- basin scales. we summarize distributions of dissolved metals commonly assayed in the calcified tissues of marine animals. Finally, we review stable isotope analysis (SIa) of amino acids and fatty acids. These analyses overcome many of the problems that prevent bulk SIa from providing sufficient geographic or trophic resolution in marine applications. we expect that ecologists will increasingly use ecogeochemistry approaches to estimate animal movements and trace nutrient pathways in ocean food webs.
    [Show full text]
  • Ocean Primary Production
    Learning Ocean Science through Ocean Exploration Section 6 Ocean Primary Production Photosynthesis very ecosystem requires an input of energy. The Esource varies with the system. In the majority of ocean ecosystems the source of energy is sunlight that drives photosynthesis done by micro- (phytoplankton) or macro- (seaweeds) algae, green plants, or photosynthetic blue-green or purple bacteria. These organisms produce ecosystem food that supports the food chain, hence they are referred to as primary producers. The balanced equation for photosynthesis that is correct, but seldom used, is 6CO2 + 12H2O = C6H12O6 + 6H2O + 6O2. Water appears on both sides of the equation because the water molecule is split, and new water molecules are made in the process. When the correct equation for photosynthe- sis is used, it is easier to see the similarities with chemo- synthesis in which water is also a product. Systems Lacking There are some ecosystems that depend on primary Primary Producers production from other ecosystems. Many streams have few primary producers and are dependent on the leaves from surrounding forests as a source of food that supports the stream food chain. Snow fields in the high mountains and sand dunes in the desert depend on food blown in from areas that support primary production. The oceans below the photic zone are a vast space, largely dependent on food from photosynthetic primary producers living in the sunlit waters above. Food sinks to the bottom in the form of dead organisms and bacteria. It is as small as marine snow—tiny clumps of bacteria and decomposing microalgae—and as large as an occasional bonanza—a dead whale.
    [Show full text]
  • Online Resources for Stable Isotope Laboratory Education and Training and Ecological Applications
    Online Resources for Stable Isotope Laboratory Education and Training and Ecological Applications Lisandra Trine, J. Renée Brooks, and William Rugh Ecological Effects Branch Pacific Ecological Systems Division Corvallis, OR, 97330 Introduction EPA’s Integrated Stable Isotope Research Facility developed a table of online educational and training resources for stable isotope analysis methods and ecological applications. This table was compiled from broad input from the stable isotope geochemistry community on the ISOGEOCHEM list serve. This resource material provides continued training of EPA and other staff in the greater stable isotope research group during situations when they may not have access to the laboratories. For any comments or recommendations to incorporate into this general listing, email [email protected]. Notice/Disclaimer Statement The views expressed in this document are those of the author(s) and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency. Any mention of trade names, products, or services does not imply an endorsement by the U.S. Government or the U.S. Environmental Protection Agency. The EPA does not endorse any commercial products, services, or enterprises. This document provides links to non-EPA web sites that provide additional information about this topic. EPA cannot attest to the accuracy of information on that non-EPA page. Copywrite laws must be considered for all material in these links. Providing links to a non- EPA Web site is not an endorsement of the other site or the information it contains by EPA or any of its employees. Also, be aware that the privacy protection provided on the EPA.gov domain (see Privacy and Security Notice) may not be available at the external link.
    [Show full text]
  • Nuclear and Isotopic Techniques for Marine Pollution Monitoring
    NUCLEAR AND ISOTOPIC TECHNIQUES FOR MARINE POLLUTION MONITORING A. Introduction The greatest natural resource on the Planet, the World Ocean is both the origin of most life forms and the source of survival for hundredsth of millions of people. Pollution of the oceans was an essential problem of the 20 century that was associated with the rapid industrializationst and unplanned occupation of coastal zones It continues to be a concern in the 21 century. The most serious environmental problems encountered in coastal zones are presented by runoff of agricultural nutrients, heavy metals, and persistent organic pollutants, such as pesticides and plastics. Oil spills from ships and tankers continually present a serious threat to birds, marine life and beaches. Also, many pesticides that are banned in most industrialized countries remain in use today, their trans-boundary pathway of dispersion affecting marine ecosystems the world over. In addition to these problems, ocean dumping of radioactive waste has occurred in the past, and might occur again, with authorised discharges of radioactive substances from nuclear facilities into rivers and coastal areas contributing to the contamination of the marine environment. A trans-boundary issue, marine pollution is often caused by inland economic activities, which lead to ecological changes in the marine environment. Examples include the use of chemicals in agriculture, atmospheric emissions from factories and automobiles, sewage discharges into lakes and rivers, and many other phenomena taking place hundreds or thousands of kilometres away from the seashore. Sooner or later, these activities affect the ecology of estuaries, bays, coastal waters, and sometimes entire seas, consequently having an impact on the economy related to maritime activities.
    [Show full text]
  • Stable Isotopes of Carbon and Nitrogen in the Study of Avian and Mammalian Trophic Ecology
    Color profile: Disabled Composite Default screen 1 REVIEW/SYNTHÈSE Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology Jeffrey F. Kelly Abstract: Differential fractionation of stable isotopes of carbon during photosynthesis causes C4 plants and C3 plants to have distinct carbon-isotope signatures. In addition, marine C3 plants have stable-isotope ratios of carbon that are 13 12 intermediate between C4 and terrestrial C3 plants. The direct incorporation of the carbon-isotope ratio ( C/ C) of plants into consumers’ tissues makes this ratio useful in studies of animal ecology. The heavy isotope of nitrogen (15N) is preferentially incorporated into the tissues of the consumer from the diet, which results in a systematic enrichment in nitrogen-isotope ratio (15N/14N) with each trophic level. Consequently, stable isotopes of nitrogen have been used pri- marily to assess position in food chains. The literature pertaining to the use of stable isotopes of carbon and nitrogen in animal trophic ecology was reviewed. Data from 102 studies that reported stable-isotope ratios of carbon and (or) nitrogen of wild birds and (or) mammals were compiled and analyzed relative to diet, latitude, body size, and habitat moisture. These analyses supported the predicted relationships among trophic groups. Carbon-isotope ratios differed among species that relied on C3,C4, and marine food chains. Likewise, nitrogen-isotope ratios were enriched in terres- trial carnivorous mammals relative to terrestrial herbivorous mammals.
    [Show full text]
  • Stable Isotope (D13c and D15n) Values of Sediment Organic Matter in Subtropical Lakes of Different Trophic Status
    J Paleolimnol (2012) 47:693–706 DOI 10.1007/s10933-012-9593-6 ORIGINAL PAPER Stable isotope (d13C and d15N) values of sediment organic matter in subtropical lakes of different trophic status Isabela C. Torres • Patrick W. Inglett • Mark Brenner • William F. Kenney • K. Ramesh Reddy Received: 22 April 2011 / Accepted: 22 February 2012 / Published online: 13 March 2012 Ó Springer Science+Business Media B.V. 2012 Abstract Lake sediments contain archives of past variables yield information about shifts in trophic environmental conditions in and around water bodies status through time, or alternatively, diagenetic and stable isotope analyses (d13C and d15N) of changes in sediment OM. Three Florida (USA) lakes sediment cores have been used to infer past environ- of very different trophic status were selected for this mental changes in aquatic ecosystems. In this study, study. Results showed that both d13C and d15N values we analyzed organic matter (OM), carbon (C), nitro- in surface sediments of the oligo-mesotrophic lake gen (N), phosphorus (P), and d13C and d15N values in were relatively low compared to values in surface sediment cores from three subtropical lakes that span a sediments of the other lakes, and were progressively broad range of trophic state. Our principal objectives lower with depth in the sediment core. Sediments of were to: (1) evaluate whether nutrient concentrations the eutrophic lake had d13C values that declined and stable isotope values in surface deposits reflect upcore, whereas d15N values increased toward the modern trophic state conditions in the lakes, and (2) sediment surface. The eutrophic lake displayed d13C assess whether stratigraphic changes in the measured values intermediate between those in the oligo-meso- trophic and hypereutrophic lakes.
    [Show full text]
  • Using Isotopes to Understand the Oceans and Climate Change
    Using Isotopes to Understand the Oceans and Climate Change A. Introduction 1. The ocean plays a critical role in modulating the earth’s climate. Recent human influence has caused the ocean to absorb additional heat and CO2, because of the increase in atmospheric CO2. The oceans absorb CO2 through physical as well as biological processes. Over the last 50 years radionuclides from both natural and anthropogenic sources have served as sensitive and increasingly indispensable tracers of ocean processes that are important in regulating climate change. Marine scientists have also applied various isotopic techniques to understand the sources, pathways, dynamics, and fate of carbon, as well as pollutants and particles that enter the oceans from land or atmosphere. For example, radiocarbon (14C) and tritium (3H) have been used to determine sources, ages, and pathways of great ocean currents and water masses; carbon-13 (13C), nitrogen-15 (15N), and phosphorus-32 (32P) have served to map ocean productivity and to track the transfer of CO2 to seawater, marine biota, and organic compounds. 2. This annex focuses on the diagnostic value of natural and anthropogenic isotopes to track ocean circulation and cycling of carbon, and to verify global ocean models which underpin future climate predictions and impacts. B. Ocean Circulation FIG. 1. The major global ocean currents that make up the ocean’s thermohaline circulation, which is driven by winds and differences in salinity and temperature due to exchange of heat and freshwater. Source: after Rahmstorf (2002) 3. The major circulation patterns of the global ocean are shown in Figure 1. Large-scale currents are driven by winds as well as seawater density differences arising from changes in salinity and temperature.
    [Show full text]
  • The Essential Role of Isotopes in Studies of Water Resources
    The Essential Role of Isotopes in Studies of Water Resources One of the prerequisites for efficient management of a water resource is reliable information about the quantity, flow and circulation of water within the resource that is being exploited. During the past two decades, isotope techniques have come to play a major role in the qualitative and quantitative assessment of water resources. In studies of surface water, isotope techniques are used to measure water runoff from rain and snow, flow rates of streams and rivers, leakage from lakes, reservoirs and canals and the dynamics of various bodies of water. Studies of groundwater resources (springs, wells) today are virtually unthinkable without isotope techniques. Basically, these techniques are simple and relatively quick. Among the many questions which may be asked of hydrologists about a given groundwater supply, often the most critical one concerns the safe yield so that the source will not run dry, or for a source to be "mined", the total yield. Isotope techniques can be used to solve such problems as: identification of the origin of groundwater, determination of its age, flow velocity and direction, interrelations between surface waters and groundwaters, possible connections between different aquifers, local porosity, transmissivity and dispersivity of an aquifer. The cost of such investigations is often small in comparison to the cost of classical hydrological techniques, and in addition they are able to provide information which sometimes cannot be obtained by other techniques. Isotope hydrology can be divided into two main branches: environmental isotope hydrology, which has become especially important in those regions of the world where basic hydrological data are insufficient, and artificial-isotope hydrology.
    [Show full text]
  • Fao/Government Cooperative Programme Scientific Basis for Ecosystem-Based Management in the Lesser Antilles Including Interactio
    FI:GCP/RLA/140/JPN TECHNICAL DOCUMENT No. 8 FAO/GOVERNMENT COOPERATIVE PROGRAMME SCIENTIFIC BASIS FOR ECOSYSTEM-BASED MANAGEMENT IN THE LESSER ANTILLES INCLUDING INTERACTIONS WITH MARINE MAMMALS AND OTHER TOP PREDATORS THE APPLICATION OF STABLE ISOTOPE ANALYSIS IN MARINE ECOSYSTEMS FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Barbados, 2008 FI:GCP/RLA/140/JPN TECHNICAL DOCUMENT No. 8 FAO/GOVERNMENT COOPERATIVE PROGRAMME SCIENTIFIC BASIS FOR ECOSYSTEM-BASED MANAGEMENT IN THE LESSER ANTILLES INCLUDING INTERACTIONS WITH MARINE MAMMALS AND OTHER TOP PREDATORS THE APPLICATION OF STABLE ISOTOPE ANALYSIS IN MARINE ECOSYSTEMS Report prepared for the Lesser Antilles Pelagic Ecosystem Project (GCP/RLA/140/JPN) by M. Aaron MacNeil School of Marine Sciences and Technology, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Barbados, 2008 The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities,or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not mentioned. The views expressed in this information product are those of the author(s) and do not necessarily reflect the views of FAO. All rights reserved.
    [Show full text]