Effects of simulated upwelling and oligotrophy on chemostat-grown natural marine phytoplankton assemblages

Natural phytoplankton assemblages from the Scripps Pier were grown in two chemostats under conditions that simulated two rates of upwelling followed by oligotrophic conditions. At a moderate upwelling rate (D = 0.3·day^?1) centric diatoms were selected, while at a low rate (D = 0.1·day^?1) a mixture of species dominated. Pumping of low-nutrient water (oligotrophy) resulted in a mixture of species at both rates. Upwelling at a high rate decreased diversity of the crop as compared with the low rate or oligotrophy. These results are compared with those of others who have subjected natural assemblages to continuous culture.     

Marine phytoplankton growth and survival under simulated upwelling and oligotrophic conditions

Dialysis cultures of a diatom, Chaetoceros affinis Lauder, and a dinoflagellate, Gymnodnium splendens Lebour were subjected to simulated upwelling conditions which were followed by oligotrophy. Upwelling was simulated by pumping nutrient-enriched sea water past the enclosed cultures. Oligotrophy was simulated by pumping nutrient-poor sea water past the cultures. After the period of upwelling oligotrophy was carried on for 65 days for G. splendens and 80 days for C. affinis. Both algae survived oligotrophic conditions as evidenced by the ability to initiate new cultures or by observation of motility. Nutrient analyses showed that oligotrophy developed slowly — over a period of several days — so that the cultures were subjected to slow changes similar to those which might occur in the sea when upwelling ceases or when upwelled water moves offshore. C. affinis responded to oligotrophy by developing small flagellated cells (male gametes), by losing discrete protoplasts in silicified cells, and by the breaking up of normal chains of cells. Plastids in G. splendens cells became more discrete under oligotrophic conditions and some large non-flagellated cells were observed. The use of dialysis cultures to simulate features of the ocean is discussed.     

Comparison of environmental indicator sets using a unified indicator classification framework

Environmental indicator sets (EIS) are tools to monitor and assess sustainability, and many environmental organizations have embraced their use. Due to the large number of EIS, it is a challenge to compare and reconcile their differences and gain a comprehensive view of their utility. To compare EIS, the first step is to classify their component indicators, for which several frameworks exist. Among the most widely used, is the causal-chain framework, also referred to as PSR after its categories of Pressure, State and Response. Other frameworks classify indicators by subject, yet none is widely applied. Aiming to compare EIS, we first proposed a unified classification criteria for indicators using PSR and five subject categories (i.e., biodiversity and ecosystem health, E; natural resources, N; physical and chemical contamination, C; human environment, H; and general, G). Then, we used these classification criteria to describe and compare fourteen existing environmental indicator sets. Finally, we compared EIS based on their production characteristics and goals. Across the fourteen EIS, we analyzed 706 indicators (which represent ∼1200 variables) and selected 16 and 79 keywords for classification in the PSR and ENCHG categories respectively. We found on average that the ratio of categories in the causal chain framework was 2.5S:1.5P:1R, while we observed a large variability across EIS. For the subject categories, C-E-N were nearly equally represented among EIS, and better represented than H-G. Also, the evaluated EIS showed a polarization between C-H and E categories that we interpreted as a human vs. natural-ecosystem welfare focus. Finally, we identified three broad categories of EIS based primarily on the organization that produced them, non-governmental organizations, governmental organizations, and international organizations. Our results can contribute to the design and implementation of scientifically robust and representative EIS, which are key to incorporate environmental data to policymaking in the search of sustainability.     

Competition between Dunaliella species at high salinity

Information on the distribution of more than 225 species of planktonic, periphytic, and benthic rotifers from diverse waters in south and central Sweden was analyzed for pH preference. No particularly strong correlation was found between pH and any other environmental factor, with regards to rotifer distribution. However, species indicating oligotrophy generally have their pH optima at or below 7.0, while those indicating eutrophy occur at or above this level. Rotifers found in acidic waters are often non-planktonic or semiplanktonic.     

Suitability of presence vs. absence indicator species to characterize stress gradients: Lessons from zooplankton species of boreal lakes

Indicator species are species that readily reflect some measure of habitat characteristics and have become an increasingly appealing tool in environmental monitoring. Traditionally, habitat conditions were derived based on the presence of specific indicator species, but the absence of indicator species may be just as informative. To evaluate the importance of presence vs. absence of indicator species for characterizing habitats across environmental gradients, we evaluated the interactions of zooplankton and acid-stress in 244 boreal lakes. We adopted the statistical methods proposed by Dufrene and Legendre (1997) to identify presence and absence indicator species to characterize high, intermediate and low acid-stress lake categories. Presence indicator species (identified by the statistical analysis) for highly stressed lakes were not entirely appropriate because further evaluation identified them as ubiquitous generalists. In contrast, absence indicators for highly stressed lakes were more appropriate as these habitat specialists were specifically absent from this category of lakes. On the other hand, presence indicators for the low acid-stress category were largely habitat specialists and therefore appropriate indicators. However there were no presence or absence indicators for lakes at intermediate acid-stress level. Thus the combined use of both presence and absence indicators is recommended to characterize habitats across a stress gradient. To evaluate if the successful application of this combined approach is dependent on a stress gradient, we applied the same analyses to a sub-set of uninfluenced (non-sensitive) lakes representing three different environmental conditions. This approach identified statistically significant presence and absence indicator species for all three different reference conditions. Yet, the absence-based approach was not essential under unstressed conditions, as presence indicator species were habitat specialists for all reference categories. Finally, this study also emphasizes the importance of meaningful ecological traits of species in order to ensure the appropriateness of statistically selected indicator species.     

Effectiveness of entropy-based functions in the analysis of ecosystem state and development

Following the advances in the field of the thermodynamics of far-from-equilibrium systems, several ecological orientors (indicators able to describe the stage and orientation of ecosystem development) incorporating entropy terms have been proposed. Although most of the proposed functions have a good theoretical basis and have proved to perform adequately as ecological indicators, their suitability as ecological orientors has yet to receive a full confirmation in real case studies. The aim of the present contribution is to examine how several entropy-based indicators (exergy, structural information, entropy production, specific entropy production and the Eco-exergy index) perform as orientors when applied to a special case of ecological succession, i.e. eutrophication, in a homogeneous set of shallow lakes lying along a trophic gradient, from oligotrophy to hyper-eutrophy. The results show that a coherent pattern of response emerge, which is also consistent with the classical ecological theory. In particular, the maximisation of storage and the minimisation of specific entropy production are confirmed as the most reliable principles of ecosystem development, whereas the maximisation of dissipation (as entropy production) appears as a debatable criterion of development.     

Measuring the sustainability of cities: An analysis of the use of local indicators

We analyze 17 studies of the use of urban sustainable development indicators (SDI) in developed western countries. The analysis reveals a lack of consensus not only on the conceptual framework and the approach favored, but also on the selection and optimal number of indicators. First, by performing different classifications and categorizations of SDI we identify problems inherent in territorial practices that use SDI. Second, we argue that the lack of consensus in several steps of the creation of SDI stems notably from the ambiguity in the definitions of sustainable development, objectives for the use of such indicators, the selection method and the accessibility of qualitative and quantitative data. Third, based on the reviewed studies, we propose a selection strategy for SDI through which we demonstrate the need to adopt a parsimonious list of SDI covering the sustainable development components and their constituent categories as broadly as possible while minimizing the number of indicators retained.     

Automated GIS-based derivation of urban ecological indicators using hyperspectral remote sensing and height information

Urban ecological indicators allow the objective and quantitative characterisation of ecological conditions in a spatially continuous way by evaluating the influence of urban surface types with respect to ecological functions and ecosystem services. Although the concept had already been developed in the 1980s, the variety of existing indicators had not been widely applied yet in urban planning practice, because of the high manual mapping effort that is required for spatially differentiated urban surface mapping. This paper presents a new automated remote sensing and GIS-based system for the flexible and user-defined derivation of urban ecological indicators. The system is based on automated surface material mapping using airborne hyperspectral image data and height information. Because the material classes obtained from remote sensing analysis differ in part from the surface types needed for the calculation of urban ecological indicators, they have been transformed into so-called linking categories representing the basis for the automated GIS-based derivation of urban ecological indicators. For this purpose, a computer-based system for flexible indicator derivation has been developed, allowing the user-defined integration of indicators based on the variable determination of mapping units, linking categories and respective weighting factors. Based on a comprehensive review of existing ecological indicators, 14 indicators have been selected and implemented in the system. To demonstrate the potential of the new system, a variety of indicators has been derived for two test sites situated in the German cities of Dresden and Potsdam, using city blocks defined by the municipal authorities as spatial mapping units. The initial mapping of surface materials was automatically performed on the basis of airborne hyperspectral image data acquired by the HyMAP system. The results of subsequent GIS-based indicator calculation were validated using results from field-based reference mapping that had been carried out for selected city blocks situated in both cities. An accuracy assessment for these reference city blocks has revealed mean errors of approximately 4%, confirming the suitability of the developed automated GIS-based system for flexible and efficient indicator calculation.     

Nature conservation: priority-setting needs a global change

The limited resources available for the conservation of biodiversity and ecosystem services call for prioritisation schemes. For instance, in the process of systematic conservation planning site selection is partly determined by efficiency gains. In this paper we present an alternative method for global spatial priority-setting based on ecological indicators, combined with social and economic conditions that influence the effectiveness of conservation, and measures for the long-term persistence of biodiversity. In the analysis the assumption made is that nature conservation should prioritize the effective maintenance of functional ecosystems that do not only provide the most ecosystem services but are also more likely to have a high adaptive capacity towards unavoidable environmental change. Furthermore, the effectiveness and permanence of conservation projects is tied to certain socioeconomic and political conditions that, as we suggest, should be evaluated as part of the conservation priority-setting process. We propose three new priority categories: eco-functionally wise (EcoWise), socioeconomically wise (SocioWise) and proactive allocation of conservation resources considering future climate change (ClimateWise) expressed as indices based on 16 different indicators. Analysing the combined effects of these three categories (EcoSocioClimateWise), in a spatially explicit way highlights the importance of tropical, subtropical but also some temperate and boreal forest areas all of which are characterized by high values of vegetation density, tree height and carbon storage. Our recommendations for policy makers prompt a shift in conservation planning towards advocating the use of ecological and socioeconomic indicators in combination with proxies for the vulnerability to future climate change impacts.     

The filter-feeders signal: response of ostracods to marine environmental changes in the Devonian F–F event

The percentage of filter-feeder species in benthic ostracod assemblages shows evident changes during the Late Devonian Frasnian–Famennian (F–F) transition with two sharp rises in the event stratal interval based on materials collected from the Yangdi section, South China. Neither anoxia nor oligotrophy, eustasy should have been the only primary cause of filter-feeders signal in the F–F event. The sea level fall and rise would create deteriorative environmental conditions such as lower oxygenation and less nutrients, which altogether reduced the diversity and abundance of the benthic ostracods in the F–F transition. The percentage of filter-feeders showed a decrease during the regression, and vice-versa. Therefore, the filter-feeders may be potentially an indicator of sea level changes in the F–F event.     

Biological Indicator Systems in Floodplains – a Review

Based on a literature review, the different approaches to biological indicator systems in floodplains are summarised. Four general categories of bioindication are defined and proposed here: 1. Classification indicators, 2.1 Environmental indicators, 2.2 Biodiversity indicators, 3. Valuation indicators. Furthermore, existing approaches in floodplains are classified according to the four categories. Relevant and widely used approaches in floodplains are explained in more detail. The results of the RIVA project are put into the context of these indication approaches. It is concluded that especially functional assessment approaches using biological traits of the species can be seen as very promising and deserve more attention by conservation biologists and floodplain ecologists. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Cultural disturbances and trophic history of a small meromictic lake from central Canada

The recent history of Little Round Lake, a small meromictic lake in southeastern Ontario, is considered. Pollen analyses were used to identify past changes in terrestrial vegetation, whilst limnological conditions were interpreted on the basis of diatom and chrysophyte microfossils. Contemporaneous with the arrival of European settlers (ca. A. D. 1850), the predisturbance assemblage of oligotrophic Cyclotella diatoms was replaced by Synedra spp., which then succeeded to a eutrophic flora dominated by Stephanodiscus hantzschii. Meanwhile, synuracean algae were almost completely excluded. Over the last 30 years, the algal microfossils indicate that the lake underwent a marked return to oligotrophy. Evidence is presented which suggests that this shift was related to the cultural enhancement of meromixis by the seepage of road salt.     

Phytoplankton biomass and primary productivity of of Lake Leake and Tooms Lake,Tasmania

Phytoplankton biomass and primary productivity were studied in two lakes in eastern Tasmania. Low standing crops (7–746 and 42–180 mm³m⁻³ for Lake Leake and Tooms Lake respectively) and low primary productivity (approx. 9 g C m⁻² yr⁻¹ for both lakes) indicate extreme oligotrophy. During a period when biomass remained constant in Lake Leake the hourly assimilation rate in constant light conditions varied seasonally, indicating physiological adjustment by the algae (“light adaptation”). The relationships between plankton biomass and carbon assimilation are discussed.     

A form-function analysis of photon capture for seaweeds

A large material of planktonic and semiplanktonic micro-crustaceans from various type of waters in south and central Sweden was computerized. The more frequent species were listed according to pH-preference and relation to humic content measured as mg Pt/l. Species indicating oligotrophy have their optima just below the neutral point, eurytopic ones around this level, while the eutrophic species Daphnia cucullata and D. magna were closely correlated with higher pH-levels. No really extreme pH-preference was observed. There is no link between trophic indication and the ranking list for humic content. Most planktic species occur at lower humic contents and semiplankters at higher.     

Cross-species identification of proteins from proteome profiles of the marine oligotrophic ultramicrobacterium, Sphingopyxis alaskensis

Sphingopyxis (formerly Sphingomonas) alaskensis is a model bacterium for studying adaptation to oligotrophy (nutrient-limitation). It has a unique physiology which is fundamentally different to that of the well studied bacteria such as Escherichia coli. To begin to identify the genes involved in its physiological responses to nutrient-limited growth and starvation, we developed high resolution two-dimensional electrophoresis (2-DE) methods and determined the identity of 12 proteins from a total of 21 spots using mass spectrometric approaches and cross-species matching. The best matches were to Novosphingobium aromaticivorans; a terrestrial, hydrocarbon degrading bacterium which was previously classified in the genus Sphingomonas. The proteins identified are involved in fundamental cellular processes including protein synthesis, protein folding, energy generation and electron transport. We also compared radiolabelled and silver-stained 2-DE gels generated with the same protein samples and found significant differences in the protein profiles. The use of both methods increased the total number of proteins with differential spot intensities which could be identified from a single protein sample. The ability to effectively utilise cross-species matching from radiolabelled and silver-stained gels provides new approaches for determining the genetic basis of microbial oligotrophy.     

The ratio of diatom frustules to chrysophycean statospores: A useful paleolimnological index

Stratigraphic analyses of the postglacial sediments of Little Round Lake and the recent sediments of two additional southern Ontario lakes were used to compare the relative abundance of fossil diatom frustules to chrysophycean statospores. Relatively few statospores were recorded during eutrophic phases in the lakes' histories such as during periods of anthropogenic activity in the lakes' catch me nt, when diatom frustules were abundant. The increased relative abundance of statospores during the early postglacial in Little Round Lake was attributed to both oligotrophy and a short growing season, conditions that currently exist in many high arctic lakes. From these data it is seen that the ratio of fossil diatom frustules to chrysophycean statospores may provide a useful paleolimnological index of trophic status in temperate lakes. The advantages of this index include its simplicity, the fact that frustules and statospores can be enumerated from the same microscope slides, and that the ratio is independent of sedimentation rates.     

Sustainability indicators for municipalities of megacities: Integrating health,safety and environmental performance

The sustainability assessment of public sector organizations including municipalities, with a focus on the integration of health, safety, and environmental (HSE) issues in the context of sustainability performance indicators, has almost remained underexplored. Moreover, since a large number of the activities of megacities’ municipalities have directly to do with HSE issues, there seems to be a substantial gap in the study of megacities and corresponding local public administrations. The present study is aimed at developing a performance evaluation tool, supported by indicators, to monitor the HSE aspects of sustainable development in the municipalities of megacities. To put the proposed tool into practice, a set of performance evaluation indicators is proposed to be adopted in Iranian municipalities, integrated in the megacity of Tehran. The selection process was conducted by employing Delphi technique. In doing so, a 2-round questionnaire was responded by qualified experts to select the most robust indicators of HSE performance and evaluate the priority of each indicator. A total of 80 indicators were generated and grouped into 13 categories, 29 sub-categories, and 7 themes- (Health (H), Safety (S), Environment (E), Health-Safety (HS), Health-Environment (HE), Safety-Environment (SE), and Health, Safety and Environment (HSE)). Findings indicate that amongst the overall average score of the 13 categories, “Fire and emergency response” is the most important category, closely followed by “Waste”, “Transportation”, and “Natural systems” categories. Moreover, among the 7 proposed themes, the integrated “HSE theme”, nearly followed by “safety theme”, plays the most significant role in enhancing the HSE performance of sustainability in Tehran municipalities. It is concluded that in the HSE context of the megacities municipalities under scrutiny, social aspects of sustainability gain more attention in comparison with the environmental ones. Furthermore, in municipalities of megacities, the indicators related to health and safety could be considered as ‘key indicators’ and should be thus classified into independent categories so that their roles can be highlighted in the management and assessment of municipal sustainable development.     

Diversity of European seagrass indicators: patterns within and across regions

Seagrasses are key components of coastal marine ecosystems and many monitoring programmes worldwide assess seagrass health and apply seagrasses as indicators of environmental status. This study aims at identifying the diversity and characteristics of seagrass indicators in use within and across European ecoregions in order to provide an overview of seagrass monitoring effort in Europe. We identified 49 seagrass indicators used in 42 monitoring programmes and including a total of 51 metrics. The seagrass metrics represented 6 broad categories covering different seagrass organizational levels and spatial scales. The large diversity is particularly striking considering that the pan-European Water Framework Directive sets common demands for the presence and abundance of seagrasses and related disturbance-sensitive species. The diversity of indicators reduces the possibility to provide pan-European overviews of the status of seagrass ecosystems. The diversity can be partially justified by differences in species, differences in habitat conditions and associated communities but also seems to be determined by tradition. Within each European region, we strongly encourage the evaluation of seagrass indicator–pressure responses and quantification of the uncertainty of classification associated to the indicator in order to identify the most effective seagrass indicators for assessing ecological quality of coastal and transitional water bodies.     

Compilation and discussion of driver,pressure, and state indicators for the Grand Bank ecosystem,Northwest Atlantic

There are global calls for new ecosystem-based fisheries management (EBFM) approaches. Scientific support for EBFM includes assessing ecosystem indicators of biological communities, environmental conditions, and human activities. As part of a broader research project we have synthesized a suite of traditional and new indicators for the Grand Bank in Atlantic Canada, which we share here. This is an ideal ecosystem for indicator analysis because it experienced dramatic changes over the past three decades, including a collapse in fish biomass that had profound socio-economic consequences. We exploit the wealth of data for this ecosystem to investigate how individual indicators reflect observed changes in the ecosystem, and then illustrate two applications of this indicator suite. Correlations were used to show that relationships among the fish functional groups changed after the collapse, and that a subset of indicators is sufficient to characterize each ecosystem category. Lagged correlations highlighted how changes in the drivers and pressures are often not immediately manifest in the fish community structure. We also organized indicators into the DPSIR (driver-pressure-state-impact-response) management framework. This exercise illustrated that indicator categorization is contextual and not straightforward, and we advocate for use of simpler categories that clearly show what is actionable. Additional future analyses that can be performed with our newly published suite of indicators are recommended.