bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biological structure and dynamics of littoral fish assemblages in the Eastern Finger Lakes
Authors: McKenna James E. 
Published: October 2002

Abstract
Fish assemblages from three of the New York Finger Lakes were examined for structure within and between lakes and over time. Species-area relationships indicated that local fish assemblages are the result of recent, lake-specific events that altered the regional species pool. Fish assemblages varied among seasons and those occupying eutrophic waters had different characteristics from those in oligotrophic waters. Bluntnose minnows (Pimephales notatus) were a persistent and important component of most assemblages, but abundance of bluegill (Lepomis macrochirus) was the most distinguishing feature. Species associations indicated that interactions among the fishes had little influence on assemblage structure. Correlations between community structure and abiotic factors were identified. Ten abiotic variables were strongly associated with the species assemblages, but could not fully explain differences between assemblages. Results indicate that the abundance and diversity of water column feeders was related to productivity of lake habitat. In general, fish populations were smaller in oligotrophic waters and water column feeders were poorly represented in those assemblages. Productivity at various trophic levels was implicated as a major factor determining lake fish assemblage structure.
Aquatic ecosystem rehabilitation: Targets, actions, responses
Authors: Zarull M. A. , Hartig J. H. 
Published: October 2002

Abstract
An effort to further define ecosystem health and integrity has been made through development and adoption of quantitative objectives for fourteen beneficial use impairments associated with the Great Lakes Areas of Concern. Narrative descriptions of beneficial use impairments have been used to develop ecosystem type indicators and objectives, which are then used to set goals for rehabilitative actions. This process is both a technical and a social one. Implementation of rehabilitative actions, in addition to being socially, technically and economically challenging has yielded both encouraging and surprising results. The process and the results have reinforced the need for an adaptive management approach to the rehabilitation of aquatic ecosystems.
Alteration of phytoplankton structure in Lake Lucerne due to trophic conditions
Authors: Bürgi H. R. , Stadelmann P. 
Published: October 2002

During the last 45 years, Lake Lucerne (Switzerland) was characterized by four major periods of varying trophic state: 1) the oligotrophic period (1955 to 1969): total phosphorus concentrations below 20 mg m−3, nitrate-nitrogen 300 to 400 mg m−3; 2) a period of accelerated eutrophication (1970 to 1977): total phosphorus concentration 20 to 30 mg m−3, nitrate-nitrogen 400 to 500 mg m−3; 3) a moderate mesotrophic period (1978 to 1988): total phosphorus concentration 20 to 25 mg m−3, nitrate-nitrogen 500 to 600 mg m−3; and 4) a period of growth limiting phosphorus concentration (1989–2001): total phosphorus concentration 5 to 10 mg m−3, nitrate-nitrogen 600 to 700 mg m−3.
The biomass, evenness, species richness and biodiversity of the plankton community was analyzed over 40 years. Annual means of biomass were not closely correlated with nutrient loading. Biodiversity, evenness and monthly changes in biomass proved to be better indicators of environmental changes. Clear water periods due to zooplankton overgrazing were observed during the mesotrophic period. The growth of phytoplankton appeared to be limited by phosphorus. Blooms of nitrogen gas-fixing (N2) cyanobacteria occurred only during the 1971 to 1983 period.
Biodiversity of periphyton (diatoms) and echinoderms around a refinery effluent, and possible associations with stability
Authors: Izsak C. , Price A. R. G. , Hardy J. T. , Basson P. W. 
Published: October 2002

We examine biodiversity in Tarut Bay, Saudi Arabia, around the effluent of a refinery that has operated since 1945. The spatial study involved quarterly assessment of diatom biodiversity in 1976/77 at 24 sites. Taxonomic distinctness decreased significantly towards the refinery outfall, in contrast to the pattern for number of species, Simpson's index and Margalef's species richness index. Ammonia-nitrogen concentrations and primary productivity (mg chlorophyll-a cm−1 d−1) also increased significantly towards the effluent, probably due to nearby sewage/nutrient enrichment.
The spatio-temporal assessment involved comparison of echinoderm biodiversity at eight sites in 1945 through 1947 and 1977. No significant temporal differences were observed in number of species, taxonomic distinctness or beta-diversity, nor was significant correlation detected between biodiversity and proximity to the refinery outfall. The absence of obvious impact is confirmed by statistical comparison of taxonomic distinctness for echinoderms in Tarut Bay with values for the whole Gulf.
Periphyton in Tarut Bay may be perturbed towards the refinery outfall, ‘positively‘ when measured by Simpson's and other ‘absolute’ biodiversity measures, but ‘negatively’ according to taxonomic distinctness, a measure of ‘average’ properties. Hence, diatom persistence stability appears moderate to low. In contrast, the echinoderm fauna may exhibit high stability, explained by either high persistence (withstanding perturbation), or high resilience (perturbation experienced, but system reverted or acclimated to ‘normal’ Gulf state) over a time scale of 30 y.
Pollution and recovery of Lake Orta (Italy): Resilience at work?
Authors: Baudo Renato 
Published: October 2002

This paper attempts to fit the history of pollution and recovery of Lake Orta, Italy, to the ecological theory of resilience, or the ability to restore structure following perturbation. The evolution of this lake can be represented by a model of a folded surface. In the case of Lake Orta, a disturbance, represented by the onset of pollution in 1926, determined the transition to conditions of an extreme environment. If an opposite change is imposed on the environment (in this case, the liming of the whole lake), the model predicts that the ecosystem will not simply revert to the pathway that it has followed up to this point, but will evolve in a different way (hysteresis). Ultimately, the system could arrive either at similar (but never completely identical) conditions to those existing prior to the disturbance, or at some completely different state.
The variations of phytoplankton, zooplankton, benthos, and fish in Lake Orta have been summarized by applying a stochastic exponential population growth model. This model succeeds in showing how resilience and resistance combine together, offering a fairly good description of both the pollution and the recovery of the lake. It can be concluded that at least nothing contradicts the hypothesis that past changes can be explained by the ecological theory of resilience and resistance.
Governance of transboundary pollution in the Danube River
Authors: McGlade Jacqueline M. 
Published: October 2002

Two major issues now influence the effective governance of transboundary pollution in major watercourses such as the River Danube: One is institutional responsiveness in light of changes in global politics and the other relates to the dynamics of the river ecosystem itself. As a result of shifts in economic and political activities arising from globalization a new geography is taking shape in which many nation-states have become 'hollowed-out' and unable to deal properly with environmental issues across varying geographic scales. Without strong institutional frameworks and clear leadership, pathological syndromes can flourish, leading to further significant environmental problems and disparities in ecosystem health.
Similarly, ecosystems do not exist in a steady state; they constantly react to both external and internal changes in ways that cause sudden, and sometimes dramatic, shifts in their make-up. Changes can occur because of subtle long-term alterations as well as catastrophic events. However, if an ecosystem has a high degree of resilience it may recover from a catastrophic event without any intervention. It is very important to understand whether or not particular ecosystems are or are not likely to recover, so that appropriate contingency planning, especially for transboundary aquatic ecosystems, can be undertaken. However, embedding resilience within current management regimes requires a shift in thinking from operating on an ad hoc basis where ecosystems are treated as static entities to one based on the generic principles of dynamical systems.
This paper explores the ramifications of various ecological, legal and social processes on transboundary aquatic system management of the River Danube in central and eastern Europe.
Key elements of fisheries management on Lake Victoria
Authors: van der Knaap M. , Ntiba M. J. , Cowx I. G. 
Published: October 2002

The fisheries of Lake Victoria have always been dynamic and the relevant authorities have continually tried to manage them. During the second half of the last century, numerous changes took place and fisheries managers had to cope with influences other than exploitation, including species introductions, invasive weeds, lake level rise, changes in water quality, and illegal fishing practices. These have influenced the way the fisheries have been managed.
In the 1920s, measures existed to manage the fisheries of Lake Victoria. In those days, a minimum net mesh size of one inch was in place, as well as certain restrictions for trawling and other fishing methods. Over the years, certain fishing gears and methods have been banned; some bans were lifted and then reimposed; minimum mesh sizes have shifted as a result of changing species compositions and changing needs to protect components of the stock. More recently, the fishery has been subjected to a series of bans on export to the European Union because of outbreaks of cholera and fish poisoning practices.
This article presents an overview of fisheries management on Lake Victoria, the successes and failures, impacts of fish exploitation and invasive weeds on species diversity, results of a major research project on the lake to assess the status of the fisheries, and the way forward.
Comparison of thermal stratification, light attenuation, and chlorophyll-a dynamics between the ends of Lake Tanganyika
Authors: Langenberg V. T. , Mwape L. M. , Tshibangu K. , Tumba J.-M. , Koelmans A. A. , Roijackers R. , Salonen K. , Sarvala J. , Mölsä H. 
Published: October 2002

Thermal structure, light attenuation, and chlorophyll-a dynamics within the upper 100 m at the northern and southern ends of Lake Tanganyika were measured from August 1995–July 1996. Pronounced variability of thermal structure in time, depth and region were observed. During the dry windy season (June–September), the water column in the south was largely isothermal down to 100 m, while in the north stratification was detectable. Subsequently, in October, cessation of winds coincided with a reestablishment and strengthening of thermal stratification in the south, and a distinct rise of a weakened thermocline in the north was accompanied by an increase in epilimnetic concentrations of dissolved solids.
The depth of photic zone was highly variable with the average position of 1% of incident photosynthetically active radiance found between 20 and 70 m, sometimes showing vertical shifts of 25 m a week. Weekly observations showed that concentrations of chlorophyll-a were rather similar at both ends of the lake. At both stations, periods of unstable or absent thermal stratification were accompanied by increased concentrations of chlorophyll-a, although in the north chlorophyll-a also peaked during periods of deep thermal stratification and low rates of mixing. Concentrations of chlorophyll-a did not show significant relationship with the available amount of underwater available photosynthetically active radiance (Im from 11–173 μEm−2 s−).
We suggest that in Lake Tanganyika chlorophyll-a maxima can occur whenever growth rates exceed spatial mixing rates, that is, if mixing is less than a critical turbulence. Our observations underscore the consequences of hydrodynamic processes on biological productivity either by securing internal nutrients or by controlling the timing and magnitude of phytoplankton biomass production.
Pelagic food web as the basis of fisheries in Lake Tanganyika: A bioenergetic modeling analysis
Authors: Sarvala Jouko , Tarvainen Marjo , Salonen Kalevi , Mölsä Hannu 
Published: October 2002

Fisheries in Lake Tanganyika, East Africa, are mainly based on two predominantly planktivorous clupeids (Stolothrissa tanganicae and Limnothrissa miodon) and a centropomid predator (Lates stappersi), caught with lift nets, purse seines, and beach seines by traditional, artisanal, and industrial fishers. The biological basis and sustainability of the present fisheries were assessed in a comprehensive project “Research for the Management of the Fisheries on Lake Tanganyika” in 1992–1998. Production in the whole lake was estimated for the entire pelagic food chain leading to the commercially important fish species. Preliminary calculations based on a constant production efficiency suggested that while the crustacean zooplankton production was sufficient to maintain the estimated planktivorous fish production, the food requirements of piscivorous fish exceeded the production of potential prey.
Here, the food consumption by pelagic fish was estimated with a bioenergetic model using actual diet data for different size classes. In order to reveal potential differences in the food web sustaining the fisheries, separate calculations were made for different parts of the lake, which harbor different fish community compositions and size structures. According to the bioenergetic calculations, the food requirements of the planktivorous fish were a reasonable fraction (25–38%) of the zooplankton production. In contrast, very high predation pressure was indicated on shrimps (73–104%), and especially on prey fish (&gt;100%), suggesting that the total biomass of the prey planktivores had been underestimated, or that the predatory fish biomass was overestimated.
Annual catch of Stolothrissa tanganicae was 18–35% of estimated production in individual countries and 25% in the whole lake. For Limnothrissa miodon , the corresponding ratio was moderately low (19–22%) in Tanzania and Zambia, but high (55–61%) in Democratic Republic of Congo and Burundi; in the whole lake, the exploitation rate was 30%. For Lates stappersi , the catch/production ratios were very high (76–112%) in all parts of the lake, and even the lakewide average exploitation rate was as high as 94%. These figures suggest that the present clupeid fishery is on a sustainable basis, while the Lates populations are clearly overexploited.
Planktonic ciliates of the North American Great Lakes: Lakes Superior, Huron, Erie, and Ontario
Authors: Munawar Mohiuddin , Lynn Denis H. 
Published: October 2002

Lakewide information about the planktonic ciliates of the North American Great Lakes has been lacking. Previously published data are limited spatially and temporally and based on few samples. This article focuses on ciliates sampled in lakewide longitudinal surveys conducted by Fisheries and Oceans Canada in four of the Great Lakes. Extensive sampling (n = 442) was conducted at stations distributed across Lakes Superior, Huron, Erie, and Ontario in various years from 1979–2000. The study focuses on abundance, biomass, and size spectrum. Our data demonstrate that ciliates contribute significantly to the planktonic communities of the Great Lakes. Mean abundance ranged from &lt;1.0 to &gt;14,000 l−1. Mean biomass ranged from &lt;1.0 to &gt;680 mg m-3. The mean abundance and biomass values are comparable to those reported earlier by other investigators from Great Lakes and other temperate lakes. Abundance and biomass differences, between the upper and lower Great Lakes, decreased from the 1980s compared to 1990s sampling when four- to ten-fold and two-fold decreases were recorded for the lower and upper Great Lakes, respectively. The six most common genera in these samples were Askenasia, Halteria, Balanion, Strobilidium, Strombidium, and Urotricha.
The ciliate community was dominated by cells &lt;30 μm equivalent spherical diameter. Pre- and post-zebra mussel size spectra of ciliates were compared for Lakes Erie and Ontario. The mean equivalent spherical diameter was significantly greater in Lake Erie in the post years compared to pre-mussel period. On the other hand, in Lake Ontario the mean diameter was significantly greater in the pre-mussel period than the post. It is likely that shifts in these distributions may be due to shifts in the relative abundance of the prey species of the ciliates. Among other factors, zebra mussels may be indirectly influencing the size-frequency distribution of the ciliate community.
CUTTING CARBON EMISSIONS AT A PROFIT (PART I): OPPORTUNITIES FOR THE UNITED STATES
Authors: Krause Florentin , DeCanio Stephen J. , Hoerner J. Andrew , Baer Paul 
Published: October 2002

This article identifies and corrects shortcomings in recent modeling studies on the economics of reducing greenhouse gas emissions in the United States. The major assessments of the Kyoto Protocol—by the U.S. Energy Information Administration, the Clinton White House Council of Economic Advisers, the U.S. Department of Energy Interlaboratory Working Group, and the Stanford Energy Modeling Forum—are found to be seriously incomplete. Each study omits one or several of four major cost‐reducing policy options, resulting in cost estimates that are far too pessimistic.In the present study, these shortcomings are overcome through the integrated evaluation of all major cost‐cutting policy options within a coherent least‐cost framework. Three domestic policies—a national carbon cap and permit trading program, productivity‐enhancing market reforms and technology programs, and recycling of permit auction revenues into economically advantageous tax cuts—are combined with international emissions allowance trading.This analysis shows that an integrated least‐cost strategy for mitigating U.S. greenhouse gas emissions would produce an annual net output gain of roughly 0.4% of GDP in 2010 and about 0.9% of GDP in 2020. On a cumulative net present value basis, the United States would gain $250 billion by 2010 and $600 billion by 2020. International flexibility mechanisms (including emissions trading) are of only secondary significance in realizing these productivity, output, and welfare gains.
Subfossil mammalian tracks (Flandrian) in the Severn Estuary, S. W. Britain: mechanics of formation, preservation and distribution
Authors: Allen J. R. L. 
Published: October 2002

Mammalian tracks and trackways are widely preserved at all stratigraphical levels in the Flandrian sediments of tidal mudflat and marsh origins which formed over the last 8000–9000 years on the marginal wetlands of the inner Bristol Channel and Severn Estuary. The fauna recorded in this way, however, is less diverse than that known from the few, small assemblages of skeletal remains, including some from archaeological sites, so far assessed. Missing or rarely represented in terms of tracks are the smaller of the large mammals. Humans are represented by tracks throughout the Flandrian deposits. In the earlier Flandrian, they were accompanied by deer and aurochs which gave way, in the later Flandrian, to domesticated cattle and sheep/goat; there are sporadic indications of the presence of horse. Wolf/dog, represented by just two records, is the only smaller large mammal so far recorded as a track.
The tracks were made, modified, and eventually preserved under a wide variety of sedimentological conditions on the margins of the estuary. Those environmental conditions constrained the quality of the anatomical evidence preserved in the tracks but can be inferred from the character of the tracks. Field experiments suggest that the moisture content of the sediment at the time was crucial to the general nature of the tracks. The mudflat–marsh silts which received the tracks varied from semi–liquid to firm, depending on tidal and seasonal factors and on the elevation of the sedimentary surface relative to the tidal frame. Some tracks were made in marsh peats which offered little resistance. Deep tracks preserving little detail were produced in weak sediments of high moisture content; tracks formed in strong, firm muds retained full anatomical detail. Referring to mechanical theory, and to a series of laboratory experiments using plasticine, the act of making a track is shown to be similar in character and effect to the indentation of an ideal elastic–plastic material by a punch. The punch represents the descending limb of the animal, the face of the punch the sole of the animal's foot, and the elastic–plastic material the sediment which is pierced and deformed by the downward action of the limb. The character of the experimental tracks, and the range and relative size of the deformation structures they include, is qualitatively similar to what is recorded from the field. Many of the tracks recorded from the field were variously modified in a changeable and dynamic environment before final burial and preservation.
Cerebral oxygenation and haemodynamics in the foetus and newborn infant
Authors: Wyatt John S. 
Published: October 2002

Quantitative techniques have been derived for the measurement of global cerebral blood flow, cerebral blood volume, its reponse to changing arterial carbon dioxide tension and mixed cerebral venous saturation in the human newborn undergoing intensive care. Normal ranges have been established and significant disturbances of cerebral oxygenation and perfusion have been demonstrated in a variety of pathological conditions. Recently, absolute cerebral deoxyhaemoglobin concentration has been obtained in the newborn using second differential spectroscopy. When combined with the measurement of total cerebral haemoglobin concentration, the mean saturation of cerebral blood (SmcO2) may be obtained, allowing global cerebral oxygenation to be determined continuously in the intensive care unit.Marked changes in the concentrations of cerebral oxy– and deoxyhaemoglobin have been observed in foetuses undergoing labour. Measurements of SmcO2from the foetal brain prior to delivery have shown the unexpected close correlation with acid–base status at birth Although movement artefact remains a theoretical risk during uterine contractions, preliminary measurements of optical path length by intensity–modulated spectroscopy have demonstrated only small fluctuations. In future the clinical application of time, phase and spatially resolved spectroscopy is likely to improve both the quantitative accuracy and the regional specificity of physiological measurements in the foetal and neonatal brain.