Linking Freshwater Flows and Ecosystem Services Appropriated by People: The Case of the Baltic Sea Drainage Basin

Humanity's dependence on ecosystem support is “mentally hidden” to large segments of society; it has no price in the market and is seldom accounted for in decision making. Similarly, the needs of ecosystems for fresh water for generation of nature's services are largely invisible. Freshwater assessments predominantly have focused on human uses of liquid water in rivers, lakes, and reservoirs. We estimated the spatial appropriation of terrestrial and marine ecosystems—the ecological footprint—of the 85 million inhabitants in the Baltic Sea drainage basin with regard to consumption of food and timber and waste assimilation of nutrients and carbon dioxide. We also estimated the amount of fresh water—the water vapor flow—that the inhabitants depend upon for their appropriation of these ecosystem services. The ecological footprint estimate corresponds to an area as large as 8.5–9.5 times the Baltic Sea and its drainage basin with a per capita ecosystem appropriation of 220,000–250,000 m². This large estimate is mainly attributed to carbon sequestering by marine ecosystems and forests. The water vapor flow of the ecological footprint of forests, wetlands, agriculture, and inland water bodies for making the human appropriation of ecosystem services possible is estimated at 1175–2875 km³ y⁻¹. Human dependence on water vapor flows for ecosystem services is as great as 54 times the amount of freshwater runoff that is assessed and managed in society. Decision making on an increasingly human-dominated planet will have to address explicitly the critical interdependencies between freshwater flows and the capacity of ecosystems to generate services. We advocate a dynamic ecohydrological landscape-management approach upstream and downstream in watersheds to reduce unintentional impacts, irreversible change, and further loss of freshwater resources, ecosystem services, and resilience. Received 6 October 1998; accepted 30 March 1999.     

Understanding Long-Term Changes in Species Abundance Using a Niche-Based Approach

One of the major challenges to understanding population changes in ecology for assessment purposes is the difficulty in evaluating the suitability of an area for a given species. Here we used a new simple approach able to faithfully predict through time the abundance of two key zooplanktonic species by focusing on the relationship between the species’ environmental preferences and their observed abundances. The approach is applied to the marine copepods Calanus finmarchicus and C. helgolandicus as a case study characterising the multidecadal dynamics of the North Sea ecosystem. We removed all North Sea data from the Continuous Plankton Recorder (CPR) dataset and described for both species a simplified ecological niche using Sea Surface Temperature (SST) and CPR Phytoplankton Colour Index (PCI). We then modelled the dynamics of each species by associating the North Sea’s environmental parameters to the species’ ecological niches, thus creating a method to assess the suitability of this area. By using both C. finmarchicus and C. helgolandicus as indicators, the procedure reproduces the documented switches from cold to warm temperate states observed in the North Sea.     

Ecological research in the tropical alpine ecosystems of the Venezuelan páramo: past,present and future

ABSTRACT

Background: Tropical mountain ecosystems of the Northern Andes have long fascinated researchers because of the unique conditions associated with cold climates in equatorial latitudes. More than six decades have elapsed since the beginning of systematic ecological research in the Venezuelan páramos, making them one of the best-studied tropical alpine regions in the world.

Aims: We review the conceptual development and state of the art of ecological research in the Venezuelan páramos, with emphasis on environmental and plant ecology research, presenting a general framework for the studies included in this special issue.

Methods: We provide a historical sketch of the periods that have marked ecological studies in the Venezuelan páramos. Then, we synthesise research on environmental drivers, plant population and community ecology, ecosystem functioning, the response of the páramo to climate change and human disturbance; we finally consider agroecology and conservation.

Results and conclusions: This review demonstrates the significant contributions made to alpine ecology in key areas such as biodiversity/ecosystem function changes during succession, nutrient cycling, species interactions and socio-ecological research. We indicate the need to develop a more integrated view of the links between evolutionary processes, functional diversity, community dynamics and ecosystem services both in natural and human-impacted areas.     

Introduction into the ecosystem of the North Sea: Hydrography,biota, and food web relationships

The North Sea, one of the most productive of the earth's seas and oceans, is also surrounded by some of earth's most densely populated and heavily industrialized regions. A growing number of signals are being received which indicate that this valuable ecosystem is increasingly under stress. This has generated a corresponding increase in concern over the steps to be taken to protect the North Sea. While there are divergent views on what constitutes an ‘ideal’ North Sea, there is a general recognition that any decisions that are made should be based on a good understanding of this ecosystem. The intention of this paper is to give an overview of what is presently known, and to identify areas where more studies are needed. A brief summary of the hydrography and the biota of the North Sea is given. Biotic and abiotic structure justify partitioning the North Sea into three ecologically different regions: southern, central, and northern. For the most part, neither the top predators,e.g. marine birds and mammals, nor the macroalgae and sea grasses are included in this overview.     

Synergistic Effects of Climate and Fishing in a Marine Ecosystem

Current climate change and overfishing are affecting the productivity and structure of marine ecosystems. This situation is unprecedented for the marine biosphere and it is essential to understand the mechanisms and pathways by which ecosystems respond. We report that climate change and overfishing are likely to be responsible for a rapid restructuring of a highly productive marine ecosystem with effects throughout the pelagos and the benthos. In the mid-1980s, climate change, consequent modifications in the North Sea plankton, and fishing, all reduced North Sea cod recruitment. In this region, production of many benthic species respond positively and immediately to temperature. Analysis of a long-term, spatially extensive biological (plankton and cod) and physical (sea surface temperature) dataset suggests that synchronous changes in cod numbers and sea temperature have established an extensive trophic cascade favoring lower trophic level groups over economic fisheries. A proliferation of jellyfish that we detect may signal the climax of these changes. This modified North Sea ecology may provide a clear indication of the synergistic consequences of coincident climate change and overfishing. The extent of the ecosystem restructuring that has occurred in the North Sea suggests we are unlikely to reverse current climate and human-induced effects through ecosystem resource management in the short term. Rather, we should understand and adapt to new ecological regimes. This implies that fisheries management policies will have to be fully integrated with the ecological consequences of climate change to prevent a similar collapse in an exploited marine ecosystem elsewhere. Author Contributions  RRK conceived the project and GB analysed the data. RRK, GB and JAL co-wrote the paper.     

Predictive ecosystem research in the Wadden Sea

Predictive ecosystem research needs a pluralistic approach. Retrospective studies reveal the initial causes of ongoing ecological change. In the Wadden Sea, inherent ecosystem stability may be falsely assumed, because the effects of modern coastal architecture and of anthropogenic eutrophication to some extent complement each other. Expected environmental changes often have corresponding phases in the past which may serve as a model to predict ecological implications. Historically, quantitative ecology entered the Wadden Sea, via fisheries research, from the oceanic side. Quantified material fluxes may reveal imbalances which are indicative of the rough direction of ecosystem change. For ecosystem research to contribute to the maintenance of the Wadden Sea as a centre of coastal organisms, quantitative knowledge of resources and ecosystem metabolism must be supplemented by qualitative knowledge of habitat requirements and species interdependences. Qualitative ecology entered the Wadden Sea from the landward side. Extending this approach to anticipatory field experiments may help to predict ecological changes at the species level.     

Multi‐decadal and ontogenetic trophic shifts inferred from stable isotope ratios of pinniped teeth

Identifying and characterizing top predators’ use of trophic resources provides important information about animal ecology and their response to changing conditions. Information from sources such as stable isotopes can be used to infer changes in resource use as direct observations in the wild are difficult to obtain, particularly in the marine environment. Stable carbon and nitrogen isotope values were recovered from the canine teeth of grey seals collected from haul outs in the central North Sea in the 1970/1980s (n = 44) and 2000s (n = 25), spanning a period of marked ecosystem changes in the region. Extracting material deposited during juvenile and adult life‐stages, we reconstructed a multi‐decadal record of δ¹⁵N and δ¹³C variation. Using established correlations between stable isotope ratios and sea bottom temperature we created a proxy for baseline isotopic variability to account for this source of temporal change. We found 1) a significant long‐term decline in juvenile grey seal δ¹⁵N values, suggesting trophic position has decreased over time; 2) a decline in adult δ¹⁵N values and contraction in stable isotopic niche space after the North Sea regime shift, signifying both a decline in trophic position and change in foraging habits over the 20th century; and 3) evidence for dietary segregation between juvenile and adult animals, showing juvenile individuals feeding at a lower trophic position and in more nearshore areas than adults. Our results demonstrate the efficacy of mining archived biological samples to address ecological questions and imply important ontogenetic and long‐term shifts in the feeding ecology of a top predator. Long‐term changes in grey seal trophic dynamics may be partly in response to well documented ecosystem changes in the North Sea. Such indirect monitoring of marine predators may have utility when set in the context of ecosystem assessments where paucity of long‐term monitoring data is prevalent.     

Tropical grassy biomes: linking ecology,human use and conservation

Tropical grassy biomes (TGBs) are changing rapidly the world over through a coalescence of high rates of land-use change, global change and altered disturbance regimes that maintain the ecosystem structure and function of these biomes. Our theme issue brings together the latest research examining the characterization, complex ecology, drivers of change, and human use and ecosystem services of TGBs. Recent advances in ecology and evolution have facilitated a new perspective on these biomes. However, there continues to be controversies over their classification and state dynamics that demonstrate critical data and knowledge gaps in our quantitative understanding of these geographically dispersed regions. We highlight an urgent need to improve ecological understanding in order to effectively predict the sensitivity and resilience of TGBs under future scenarios of global change. With human reliance on TGBs increasing and their propensity for change, ecological and evolutionary understanding of these biomes is central to the dual goals of sustaining their ecological integrity and the diverse services these landscapes provide to millions of people.This article is part of the themed issue ‘Tropical grassy biomes: linking ecology, human use and conservation’.     

Biodiversity in the Black Sea: effects of climate and anthropogenic factors

The Black Sea ecosystem and diversity underwent dramatic adverse changes during the 1960s and, especially, 1970s and 1980s of the last century. Anthropogenically-induced eutrophication increased through greater biogenic flow, dumping and pollutant discharge, in turn causing red tides, fish kills and oxygen depletion over the northwestern shelf. Anthropogenic pressures, associated with the economic situation of the Black Sea countries, has decreased during the last decade, allowing some improvement in the state and biodiversity of the ecosystem. The abundances of several native species have increased. However, mediterranization—the invasion by species from the adjacent basin and beyond—has continued. The conclusion is grounded, that biodiversity is not only inter- and intra-species diversity but also spatial–temporal variability, abundance and productivity dynamics, differences of the metabolic strategies providing sustainable existence in the changing environment. Biodiversity at the intra-species level expresses itself in spatial and temporal variations of the Black Sea biota. It has been shown, that рreservation of the Black Sea ecosystem’s biodiversity must be based on the measures which should be undertaken in national and social spheres, and be directed to the recreation, stabilization and conservation of this unique sea basin. Measures must be implemented nationally to conserve, stabilize or recreate the ecosystem biodiversity of this unique sea basin.     

The potential of and limitations to marine population prognosis

Following the 19th century recognition and definition of basic ecological entities, functional analysis has been the highlight of this century. The synthesis of these findings enables ecological prognosis. The population as the basic functional unit has been repeatedly treated; in the marine field, fisheries management approaches developed into multi-species population analysis. As in planktology, theoretical ecology, and classic biocoenotic research, the population interactions are of increasing scientific interest. A mathematical model is suggested that combines these extrinsic and intrinsic functional relationships in order to define the fit of the ecological niche to the environment, the decisive measure of the expected population success, and thus of the probable population development needed for prognostic purposes. It is discussed in how far the orientation towards the predictive power or — with respect to the “skill” of meteorological prognoses — the “ecological prognostic skill” improvement may serve as a means to choose the best investigative strategy.     

Grasshopper (Orthoptera: Acrididae) communities respond to fire,bison grazing and weather in North American tallgrass prairie: a long-term study

Because both intrinsic and extrinsic factors influence insect population dynamics, operating at a range of temporal and spatial scales, it is difficult to assess their contributions. Long-term studies are ideal for assessing the relative contributions of multiple factors to abundance and community dynamics. Using data spanning 25 years, we investigate the contributions of weather at annual and decadal scales, fire return interval, and grazing by bison to understand the dynamics of abundance and community composition in grasshopper assemblages from North American continental grassland. Each of these three primary drivers of grassland ecosystem dynamics affects grasshopper population and community dynamics. Negative feedbacks in abundances, as expected for regulated populations, were observed for all feeding guilds of grasshoppers. Abundance of grasshoppers did not vary in response to frequency of prescribed burns at the site. Among watersheds that varied with respect to controlled spring burns and grazing by bison, species composition of grasshopper assemblages responded significantly to both after 25 years. However, after more than 20 years of fire and grazing treatments, the number of years since the last fire was more important than the managed long-term fire frequency per se. Yearly shifts in species composition (1983–2005), examined using non-metric multidimensional scaling and fourth-corner analysis, were best explained by local weather events occurring early in grasshopper life cycles. Large-scale patterns were represented by the Palmer Drought Severity Index and the North Atlantic Oscillation (NAO). The NAO was significantly correlated with annual mean frequencies of grasshoppers, especially for forb- and mixed-feeding species. Primary grassland drivers—fire, grazing and weather—contributing both intrinsic and extrinsic influences modulate long-term fluctuations in grasshopper abundances and community taxonomic composition. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Assessment of bioinvasion impacts on a regional scale: a comparative approach

This paper presents an overall bioinvasion impact assessment on the scale of a large marine region—the Baltic Sea, as defined by the Helsinki Commission. The methodology is based on a classification of the abundance and distribution range of alien species and the magnitude of their impacts on native communities, habitats and ecosystem functioning aggregated in a “Biopollution Level” index (BPL) which ranges from ‘no impact’ (BPL = 0) to ‘massive impact’ (BPL = 4). The assessment performed for nine Baltic sub-regions revealed that documented ecological impact is only known for 43 alien species out of 119 registered in the Sea. The highest biopollution (BPL = 3, strong impact) occurs in coastal lagoons, inlets and gulfs, and the moderate biopollution (BPL = 2)—in the open sea areas. The methodology was also used to classify species into alien (BPL = 0) versus ‘impacting’ species (BPL > 0), which can be divided into ‘potentially invasive’ (BPL = 1) and ‘invasive’ (BPL > 1) ones. No clear correlation between the number of established alien and impacting species was found in the sub-regions of the Baltic Sea. The methodology, although requiring a substantial research effort, proved to be useful for interregional comparisons and evaluating the bioinvasion effects of individual alien species.     

Community genetics: what have we accomplished and where should we be going?

Research in community genetics seeks to understand how the dynamic interplay between ecology and evolution shapes simple and complex communities and ecosystems. A community genetics perspective, however, may not be necessary or informative for all studies and systems. To better understand when and how intraspecific genetic variation and microevolution are important in community and ecosystem ecology, we suggest future research should focus on three areas: (i) determining the relative importance of intraspecific genetic variation compared with other ecological factors in mediating community and ecosystem properties; (ii) understanding the importance of microevolution in shaping ecological dynamics in multi-trophic communities; and (iii) deciphering the phenotypic and associated genetic mechanisms that drive community and ecosystem processes. Here, we identify key areas of research that will increase our understanding of the ecology and evolution of complex communities but that are currently missing in community genetics. We then suggest experiments designed to meet these current gaps.     

Species-specific PCR discrimination of species of the calanoid copepod Pseudocalanus, P. acuspes and P. elongatus, in the Baltic and North Seas

Two species of the calanoid copepod Pseudocalanus, P. acuspes and P. elongatus, have been reported from the Baltic and North Seas. Morphometric analysis based on Frost (Can J Zool 67:525–551, 1989) did not identify the species in samples collected during the German GLOBEC program; the majority of measurements fell outside reported ranges for Baltic and North Sea specimens. A multiplexed species-specific PCR (SS-PCR) protocol was designed from a ~700 bp sequence of mitochondrial cytochrome oxidase I (mtCOI), with primers designed to amplify regions of different sizes for the two species to allow detection by gel electrophoresis. The accuracy and reliability of the multiplexed SS-PCR reaction was confirmed by sequencing the mtCOI region. Preliminary SS-PCR analysis of geographic distributions of the two species indicated that P. acuspes occurred exclusively at sampling sites in the Baltic Sea, whereas P. elongatus was found in the southern North Sea and at one site in the Baltic. The SS-PCR protocol can be used for routine identification of the two species for studies of population, community and ecosystem dynamics.     

Nutrient emission reduction scenarios in the North Sea: An abatement cost and ecosystem integrity analysis

Economic cost–benefit appraisal (and its sub-set cost-effectiveness) of ecosystem conservation and/or pollution abatement strategies have proved to be powerful decision-making aids. But the monetary economic valuation of ecosystem goods and services (gains and losses) can only provide a good indication of social welfare impacts under certain conditions and in selective contexts. The values derived through this appraisal process will, for a number of measures, be underestimates of the full total system value [Turner, R.K., Paavola, J., Cooper, P. Farber, S., Jessamy, V., Georgiou, S., 2003. Valuing nature: lessons learned and future research directions. Ecol. Econ. 46, 493–510]. The economic analysis is best suited to assessing the value of ‘marginal’ gains and losses in ecosystem goods/services and not the total destruction of whole systems (including life support systems, the value of which is not commensurate with monetary values and/or is infinitely high). In this study economic costs and what we call ‘ecological risk’ analysis are used to appraise the implementation costs and ecological benefits of selected measures for combating eutrophication. Ecological risk is expressed in terms of ecosystem integrity and resilience. The paper presents three regional case studies dealing with the issue of nutrient emission reduction to the southern North Sea, namely the catchments/estuaries of the Humber (UK), the Rhine (Germany and The Netherlands) and the Elbe (Czech Republic and Germany). On the basis of these comparative regional examples, wider implications in the light of international management of the North Sea are presented.A range of nutrient reduction scenarios have been deployed within the overall OSPAR target agreement of 50% nitrogen and phosphorous reduction compared with 1985 levels. Each scenario assumes pollution reduction measures, characterised in terms of their overall implementation costs and nutrient-reduction effects. Specific policy instruments analysed were: the creation of more intertidal habitat via managed coastal realignment in the Humber area, farm-based land cover changes in the Rhine catchment and a mix of agricultural regime and wastewater treatment plant (WWTP) improvements in the Elbe area. The ecological consequences associated with each reduction scenario have been modelled [using the ERSEM model, see Baretta, J.W., Ebenhöh, W., Ruardij, P., 1995. An overview over the European Regional Sea Ecosystem Model, a complex marine ecosystem model. Neth. J. Sea Res. 33 (3/4), 233–246] for the coastal zones supplied from the rivers Elbe, Humber and Rhine. The modelled ecological quality indicators, which describe scenario effects on the coastal zone ecosystem, are then aggregated in terms of ecosystem integrity and ecological risk. The results are presented in terms of two selected key-indicators: implementation costs of the abatement measures and changes in ecological risk status, across the different catchments and assuming different scenarios. They thus provide a possible basis for international agreement negotiations at the North Sea scale.     

On the physical oceanography of the Kattegat and Clyde Sea area, 1996–98, as background to ecophysiological studies on the planktonic crustacean, Meganyctiphanes norvegica (Euphausiacea)

 The euphausiid, Meganyctiphanes norvegica (M. Sars), has an extremely wide distribution around the North Atlantic, from Canada to the Arctic to the western Mediterranean. It appears to be adaptable to life under quite different oceanographic conditions, yet no morphological features have been identified that distinguish any of the populations occurring in different areas between which exchange must be supposed to be restricted. The genetic, physiological, behavioural and ecological investigations that are being carried out on M. norvegica in the Kattegat, the Clyde Sea area and the Ligurian Sea (the EU MAST III PEP Project) in order to study its adaptability must be closely related to the physical environment within which the respective populations occur. This paper presents a summary of the hydrographic conditions found in the Kattegat and the Clyde Sea area in summer and in winter, during each research cruise, and places them in the context of current understanding of the hydrography in each area. An account of the hydrography of the Ligurian Sea is in preparation (Dallot et al., in preparation). The data will be used in the further analysis of genetic, physiological and behavioural adaptability of M. norvegica, and will be available for use as appropriate to supplement other hydrographic studies in the regions concerned. Received: 2 February 1999 / Accepted: 6 April 1999     

People as Ecological Participants in Ecological Restoration

In 1987, Bradshaw proposed that ecological restoration is the ultimate “acid test” of our understanding the functioning of ecosystems ( Bradshaw 1987 ). Although this concept is widely supported academically, how it can be applied by restoration practitioners is still unclear. This is an issue not limited to Bradshaw’s acid test, but moreover, reflects a general difficulty associated with the polarization between conceptual restoration (restoration ecology) and practical restoration (ecological restoration), where each has functioned to certain degree in isolation of the other. Outside of the more obvious pragmatic reasons for the relative independence between ecological restoration and restoration ecology, we propose that a more contentious explanation is that the approach taken toward understanding ecosystem development in restoration ecology is tangential to what actually takes place in ecological restoration. Current paradigms assume that the process of ecosystem development in restoration should follow the developmental trajectories suggested by classical ecological succession models. However, unlike these models, ecosystem development in restoration is, at least initially, largely manipulated by people, rather than by abiotic and biotic forces alone. There has been little research undertaken to explore how restoration activities impact upon or add to the extant ecological processes operating within a restoration site. Consequently, ecological restoration may not be so much an acid test of our understanding the functioning of ecosystems, but rather, an acid test of our understanding mutually beneficial interactions between humans and ecosystems.     

Adventive flora of Israel — Phytogeographical,ecological and agricultural aspects

73 adventive wild species occur in the flora of Israel: 39 are of tropical origin, 20 are North American. The geographical distribution pattern suggests that about two thirds of the species reached Israel through neighbouring countries, while only one third arrived directly from their countries of origin. — Three patterns of population dynamics can be recognized: accidental species (7), colonizing species (30), and species penetrating into natural habitats (3). There is insufficient information about the remaining species. — About 20 species are widespread noxious weeds which now have economic significance in Israel, 20 others are known to have similar ecological tendencies in other countries. These species soon may become aggressive weeds in Israel.     

The Ecosystem as a Multidimensional Concept: Meaning,Model, and Metaphor

The ecosystem is a fundamental ecological concept that is not as simple as it first appears. We explore three key dimensions of the concept that make it both complex and broadly useful—its basic definition, its application via models to concrete or specific situations, and its metaphorical connotations as used in general communication within the domain of science and with the public at large. Clarity in identifying what the dimensions are and how they are related can help to maintain the rigor of the concept for specific scientific uses while also allowing enough flexibility for its use in the integration of scientific principles, as well as in public discourse. This analysis of the ecosystem as a multidimensional concept is likely to be generalizable to other important concepts in ecology. Received 28 February 2001; accepted 5 September 2001.     

Marine biological shifts and climate

Phenological, biogeographic and community shifts are among the reported responses of marine ecosystems and their species to climate change. However, despite both the profound consequences for ecosystem functioning and services, our understanding of the root causes underlying these biological changes remains rudimentary. Here, we show that a significant proportion of the responses of species and communities to climate change are deterministic at some emergent spatio-temporal scales, enabling testable predictions and more accurate projections of future changes. We propose a theory based on the concept of the ecological niche to connect phenological, biogeographic and long-term community shifts. The theory explains approximately 70% of the phenological and biogeographic shifts of a key zooplankton Calanus finmarchicus in the North Atlantic and approximately 56% of the long-term shifts in copepods observed in the North Sea during the period 1958–2009.