Karin E. Limburg

The value of the world's ecosystem services and natural capital

This article provides a crude initial estimate of the value of ecosystem services to the economy. Using data from previous published studies and a few original calculations the current economic value of 17 ecosystem services for 16 biomes was estimated. The services of ecological systems and the natural capital stocks that produce them are critical to the functioning of the Earths life-support system. They contribute to human welfare both directly and indirectly and therefore represent part of the total economic value of the planet. It was estimated that for the entire biosphere the value (most of which is outside the market) ranges US

Complex systems and valuation

16-54 trillion/year with an average of US

Dramatic Declines in North Atlantic Diadromous Fishes

33 trillion/year. Due to the nature of uncertainties this must be considered a minimum estimate. In addition the global gross national product total is around US

The value of ecosystem services: putting the issues in perspective

18 trillion/year.

The use of otolith chemistry to characterize diadromous migrations.

Abstract Ecological and economic systems are undeniably complex. Whereas a goal of delineating ‘ecosystem services’ is to make readily apparent some of the important ways in which ecosystems underpin human welfare, insights are also gained by appreciating the nonlinear dynamic properties of ecosystems. In this paper, we review some of the relevant characteristics of complex systems. Ecosystems and economic systems share many properties, but valuation has typically been driven by short-term human preferences. Here we argue that as the force of humanity increases on the planet, ecosystem service valuation will need to switch from choosing among resources to valuing the avoidance of catastrophic ecosystem change.

THROUGH THE GAUNTLET AGAIN: DEMOGRAPHIC RESTRUCTURING OF AMERICAN SHAD BY MIGRATION

We examined the status of diadromous (migratory between saltwater and freshwater) fishes within the North Atlantic basin, a region of pronounced declines in fisheries for many obligate marine species. Data on these 24 diadromous (22 anadromous, 2 catadromous) species are sparse, except for a few high-value forms. For 35 time series, relative abundances had dropped to less than 98% of historic levels in 13, and to less than 90% in an additional 11. Most reached their lowest levels near the end of the observation period. Many populations persist at sharply reduced levels, but all species had suffered population extirpations, and many species are now classified as threatened or endangered. Habitat loss (especially damming), overfishing, pollution, and, increasingly, climate change, nonnative species, and aquaculture contributed to declines in this group. For those diadromous fishes for which data exist, we show that populations have declined dramatically from original baselines. We also discuss the consequences of these changes in terms of lost ecosystem services.

Tracking Baltic hypoxia and cod migration over millennia with natural tags

a Department of Zoology, Center for En6ironmental Science, Uni6ersity of Maryland, Box 38, Solomons, MD 20688, USA b Institute for Ecological Economics, Uni6ersity of Maryland, PO Box 38, Solomons, MD 20688, USA c Department of Economics (emeritus), Uni6ersity of Wyoming, Laramie, WY, 82070, USA d Center for En6ironment and Climate Studies, Wageningen Agricultural Uni6ersity, PO Box 9101, 6700 HB Wageningen, The Netherlands e Graduate School of Public and International Affairs, Uni6ersity of Pittsburgh, Pittsburgh, PA 15260, USA f Institute for Ecological Economics, Uni6ersity of Maryland, PO Box 38, Solomons, MD 20688, USA g Department of Geography, Uni6ersity of Illinois, Urbana, IL 61801, USA h NCSA, Uni6ersity of Illinois, Urbana, IL 61801, USA i Institute of Ecosystem Studies, Millbrook, NY, USA j Department of Ecology, E6olution and Beha6ior, Uni6ersity of Minnesota, St. Paul, MN 55108, USA k En6ironmental Sciences Di6ision, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA l Department of Ecology, Faculty of Agronomy, Uni6ersity of Buenos Aires, A6. San Martin 4453, 1417 Buenos Aires, Argentina m Jet Propulsion Laboratory, Pasadena, CA 91109, USA n Department of Geography, National Center for Geographic Information and Analysis, Uni6ersity of California at Santa Barbara, Santa Barbara, CA 93106, USA o Ecological Economics Research and Applications, PO Box 1589, Solomons, MD 20688, USA

Communicating with the public: opportunities and rewards for individual ecologists

Chemical constituents in otoliths have become a valuable tool for fish ecologists seeking to reconstruct migratory patterns and life-history diversity in a wide range of species worldwide. This approach has proved particularly effective with fishes that move across substantial salinity gradients over the course of their life, including many diadromous species. Freshwater endmembers of several elemental and isotope ratios (e.g. Sr:Ca, Ba:Ca and (87)Sr:(86)Sr) are typically identifiably distinct from marine values, and often differ among freshwater tributaries at fine spatial scales. Because these chemical tags are generally incorporated in proportion to their ambient dissolved concentrations, they can be effective proxies for quantifying the presence, duration and frequency of movements between freshwater and marine habitats. The development of high precision probe-based analytical techniques, such as laser ablation inductively coupled plasma mass spectrometry (ICP-MS) and microbeam methods, has allowed researchers to glean increasingly detailed life-history profiles of these proxies across otoliths. Researchers are also combining multiple chemical proxies in an attempt to refine interpretations of habitat residence patterns. A thorough understanding of the spatial and temporal variation in water chemistry as well as environmental and physiological controls on incorporation of specific elements into otoliths is required for confident estimation of lifetime salinity experience. First some assumptions, methodological considerations and data processing options that are particularly relevant to diadromous otolith chemistry studies are discussed. Insights into diadromous migrations obtained from decades of otolith chemistry research, highlighting the increasingly recognized importance of contingent behaviour and partial migration are then discussed. Finally, areas for future research and the need to integrate otolith chemistry studies into comprehensive assessments of the effects of global environmental change are identified.

Consumption, Selectivity, and Use of Zooplankton by Larval Striped Bass and White Perch in a Seasonally Pulsed Estuary

Long-distance migration in fishes is one of the more spectacular examples of ontogenetic niche switching, yet details are often obscured because of the difficulty in making direct observations on individual migrants. Juvenile emigration and ultimate re- cruitment to the spawning population were studied retrospectively in American shad (Alosa sapidissima), to look for patterns of size-biased survivorship as a consequence of migration. Adults were collected on or near the spawning grounds in the Hudson River, New York, USA, in spring 1995. Their early life histories were reconstructed by measuring strontium and calcium concentrations in the inner portions of their otoliths, which were deposited when the fish were young-of-the-year (YOY). Sudden elevations of the Sr:Ca ratio were interpreted as seaward migration events, and the physical location of these elevations on the otolith could be related to the age and size at which the fish first emigrated from fresh water. Recruited adults showed distributions of first emigration that were bimodal with respect to size and age, and these patterns were repeated in three of four year classes analyzed. In 1989 and 1990, years when YOY data were available, size distributions of apparently emigrating YOY do not agree with the distributions displayed in the otoliths of returning adults from the same year classes, suggesting that differential mortality had occurred, which was dependent on the timing of emigration. Detailed analysis was possible for the 1990 year class, which showed strong evidence in both sexes of at least two major recruitment bottlenecks-one affecting larvae hatched early, and the second affecting em- igrating juveniles hatched from late cohorts. Potential causes of differential mortality on emigrating juveniles include the presence of large predators outside of the Hudson, as well as the presence of hypoxic waters into which the fish may have entered. This study indicates that long-distance migration of juveniles can be a strong factor that restructures the de- mography of a year class of fish.

Declining oxygen in the global ocean and coastal waters

Growing hypoxic and anoxic areas in coastal environments reduce fish habitat, but the interactions and impact on fish in these areas are poorly understood. Using “natural tag” properties of otoliths, we found significant correlations between the extent of Baltic Sea hypoxia and Mn/Ca ratios in regions of cod (Gadus morhua) otoliths corresponding to year 1 of life; this is associated with elevated bottom water dissolved manganese that increases with hypoxia. Elevated Mn/Ca ratios were also found in other years of life but with less frequency. We propose that cod exhibiting enhanced Mn/Ca ratios were exposed to dissolved manganese from hypoxia-induced redox dynamics in nursery areas. Neolithic (4500 B.P.) cod otoliths (n = 12) had low levels of Mn/Ca ratios, consistent with low hypoxia, but a single otolith dated to the younger Iron Age had a distinct growth band with an elevated Mn/Ca ratio. Sr/Ca patterns reflecting changes in environmental salinity and temperature were similar in both modern and Stone Age otoliths, indicating consistent migration habits across time, and Ba/Sr ratios in modern cod otoliths indicate increasing use of a more saline habitat with age. Using elemental ratios, numerous existing archival collections of otoliths could provide the means to reconstruct hypoxia exposure histories and major patterns of fish movement near “dead zones” globally.