One hundred and sixty four plastic particles (mean length 4.1 mm) recovered from the scats of fur seals (Arctocephalus spp.) on Macquarie Island were examined. Electron micrographs of 41 of the plastic particles showed that none could be identified as plastic pellet feedstock from their shapes. Commonly, such pellets are cylindrical and spherical. Instead, all the 164 plastic particles from the seal scats were angular particles of 7 colors (feedstock particles are normally opaque or white) and could be classified into 2 categories: i) fragmented along crystal lines and likely to be the result of UV breakdown; and ii) worn by abrasion (where striations were clearly visible) into irregular shapes with rounded corners. White, brown, green, yellow and blue were the most common colors. In composition, they came from 5 polymer groups; poly-ethylene 93%, polypropylene 4%, poly(1-Cl-1-butenylene) polychloroprene 2%, melamine-urea (phenol) (formaldehyde) resin 0.5%, and cellulose (rope fiber) 0.5%. The larger groups are buoyant with a specific gravity less than that of seawater. These small plastic particles are formed from the breakdown of larger particles (fragments). Their origin seems to be from the breakdown of user plastics washed ashore and ground down on cobbled beaches. Certainly most particles (70%) had attained their final form by active abrasion. It is hypothesized that the plastic particles were washed out to sea and then selected by size and consumed by individuals of a pelagic fish species, Electrona subaspera, who in turn were consumed by the fur seals. Thus, the particles were accumulated both by the fish and the seals in the usual process of their feeding.

Bone mineral density (mg cm⁻³) was studied in male Baltic grey seals (4–23 years of age) by noninvasive computed tomography (pQCT). The material was grouped according to year of collection. Group A: 1850–1955, a period before the main introduction of organochlorines (OCs); Group B: 1965–1985, a period with very high OC contamination; and Group C: 1986–1997, a period with decreasing concentrations of OCs. The reproducibility of the measurements was good with a Coefficient of Variation (CV) ranging from 0.1% to 2.1%. Trabecular bone mineral density of the radius was significantly higher in specimens collected 1986–1997 than in those collected 1965–1985 (p < 0.05). Cortical bone mineral density of the mandible was significantly lower in specimens collected 1986–1997 compared with those collected 1850–1955 (p < 0.05). These results indicate different responses over time in trabecular and cortical bone. During the period of very high OC contamination (1965–1985), trabecular bone density was lowest, whereas cortical bone density was lowest in specimens collected 1985–1997, representing a period of fairly low OC contamination. The mechanisms behind these effects are not known. However, it can be assumed that OCs are involved. Information about residue levels of OCs in the studied individuals is lacking and, therefore, it was not possible to evaluate the impact of OCs in this respect.

In a world increasingly modified by human activities, the conservation of biodiversity is essential as insurance to maintain resilient ecosystems and ensure a sustainable flow of ecosystem goods and services to society. However, existing reserves and national parks are unlikely to incorporate the long-term and large-scale dynamics of ecosystems. Hence, conservation strategies have to actively incorporate the large areas of land that are managed for human use. For ecosystems to reorganize after large-scale natural and human-induced disturbances, spatial resilience in the form of ecological memory is a prerequisite. The ecological memory is composed of the species, interactions and structures that make ecosystem reorganization possible, and its components may be found within disturbed patches as well in the surrounding land-scape. Present static reserves should be complemented with dynamic reserves, such as ecological fallows and dynamic successional reserves, that are part of ecosystem management mimicking natural disturbance regimes at the landscape level.

During the last decade, several well-publicized grazing-related incidents of vegetation degradation have helped to form an official opinion of overutilization of some mountain areas and a concern that Swedish reindeer husbandry may not be ecologically sustainable. We examine these examples in a temporal and management perspective to assess the scale of impact on summer grazing grounds in the Swedish mountains. Long-term data on population dynamics of reindeer show no trend with fluctuations around 225 000 animals for the last century. Data on grazing effects from Långfjället (Dalarna) and Mittåkläppen (Härjedalen) are discussed in detail. We compare these data to the situation in Finnmark, Norway, and in northern Finland where reindeer husbandry in recent decades does not seem to have been ecologically sustainable. We conclude that large-scale overexploitation by reindeer in the Swedish mountains is not evident. However, strong grazing and trampling effects may be found around enclosures and fences.

The first comprehensive seaweed flora of a Brazilian region was published by Joly in 1957, describing and illustrating 105 taxa. Twenty years later Oliveira and Berchez resurveyed the area and found only 69 taxa, with a strong reduction in the number of brown algae. In another survey, performed in 1991 at the 3 studied stations with the largest species richness, the same reduction trend was found and no brown algae were observed. This reduction in biodiversity was attributed to increased pollution. Here we present the results of a new survey made in 1998–1999. This shows the return of some species recorded in the 1950s, including 7 species of brown algae. This increase in species number is thought to be a consequence of the efforts made by the local government to reduce pollution and the building of a submarine sewage terminal.

A predictive model for gas-phase PCBs and trans-nonachlor over Lake Michigan has been constructed and the resulting data examined for trends. In this paper, we describe the model results to show how the magnitude and variability of a plume of contaminants from the Chicago area contributes to a highly variable region of net contaminant deposition over the entire lake. For the whole lake, gross annual deposition of PCBs is ∼ 3200 kg, although the net annual gas exchange is not significantly different from zero. The data-driven model illustrates that on a daily basis, the net exchange of persistent organic pollutants (POPs) can change from net deposition to net volatilization depending on the area of plume impact. These findings suggest that i) control of urban areas can accelerate the rate of volatilization from lakes; and ii) release of POPs from urban areas is largely a result of volatilization processes.

The transport of organic and inorganic material in 10 Norwegian rivers has been monitored from 1990 to 1998. The suspended material in the rivers consisted of 40–80% organic materials. A major part of this was DOC with a C/N mole ratio > 25. The C/N ratio of the organic material increases with increasing river flow when drained from forest-dominated catchments, in contrast to mountain dominated catchments where variation in runoff does not influence the C/N ratio. Laboratory experiments showed that more than 90% of the DOC remained in solution when salinity increased to 30. The flocculated and settled material contained less than 5% organic material with a C/N ratio of 6.7–12.4, comparable to C/N ratios in cultivated soils and coastal marine sediments. This confirms that only a minor amount of organic material carried to the sea by rivers settles in the coastal zone.

Transformation in Polish agriculture initiated by political changes in the 1990s brought about essential variations in the structure of agricultural land use. The share of cereals in cropping patterns increased, while fodder plants decreased. In addition, the level of mineral fertilization was reduced. In livestock production animal stock showed a sharp fall, which led to a decreased load of organic fertilization. The changes in cropping pattern and lower fertilization rates resulted in a decrease in the organic matter level in soils, which may impair soil quality status. These phenomena were strongly manifested in the Wielkopolska Region mainly because of the prevalence of light soils in this area, from which nutrients are readily washed out to groundwaters. It was found that many of the negative aspects of these changes in the agricultural landscape can be mitigated by establishing shelterbelts. We conclude that shelterbeds are especially effective in the control of nutrient output from a watershed.

Alachlor, metolachlor and their respective environmentally stable aniline degradation products, 2,6-diethylaniline and 2-ethyl-6-methylaniline were analyzed in water and sediment samples from 9 sites along River Nzoia, Kenya using gas chromatography. The degradation products were detected in > 90% of the sediment and water samples, while the parent compounds occurred in < 14% of the water samples. Much higher concentrations of the pesticides and their degradation products occurred in the sediment than in the water (1.4 up to 10 800-fold), indicating an accumulation of the compounds in the sediment. The constant occurrence of the degradation products in the sediment during the study period infers a persistence of these compounds. It is hypothesized that the prevailing tropical climatic conditions favor a quick breakdown of the pesticides to their environmentally stable degradation products, thereby making the latter more important pollutants than their parent products in the study area.

Both frequency and intensity of disturbances in many ecosystems have been greatly enhanced by increasing human activities. As a consequence, the short-lived plant species including many exotics might have been dramatically increased in terms of both richness and abundance on our planet, while many long-lived species might have been lost. Such conclusions can be drawn from broadly observed successional cycles in both theoretical and empirical studies. This article discusses 2 major issues that have been largely overlooked in current ecosystem management policies and conservation efforts: i) life history constraints; and ii) future global warming trends. It also addresses the importance of these 2 factors in balancing disturbance frequency and intensity for optimal biodiversity maintenance and ecosystem management.

During the last decade, several well-publicized grazing-related incidents of vegetation degradation have helped to form an official opinion of overutilization of some mountain areas and a concern that Swedish reindeer husbandry may not be ecologically sustainable. We examine these examples in a temporal and management perspective to assess the scale of impact on summer grazing grounds in the Swedish mountains. Long-term data on population dynamics of reindeer show no trend with fluctuations around 225 000 animals for the last century. Data on grazing effects from Långfjället (Dalarna) and Mittåkläppen (Härjedalen) are discussed in detail. We compare these data to the situation in Finnmark, Norway, and in northern Finland where reindeer husbandry in recent decades does not seem to have been ecologically sustainable. We conclude that large-scale overexploitation by reindeer in the Swedish mountains is not evident. However, strong grazing and trampling effects may be found around enclosures and fences.

The first comprehensive seaweed flora of a Brazilian region was published by Joly in 1957, describing and illustrating 105 taxa. Twenty years later Oliveira and Berchez resurveyed the area and found only 69 taxa, with a strong reduction in the number of brown algae. In another survey, performed in 1991 at the 3 studied stations with the largest species richness, the same reduction trend was found and no brown algae were observed. This reduction in biodiversity was attributed to increased pollution. Here we present the results of a new survey made in 1998–1999. This shows the return of some species recorded in the 1950s, including 7 species of brown algae. This increase in species number is thought to be a consequence of the efforts made by the local government to reduce pollution and the building of a submarine sewage terminal.

A predictive model for gas-phase PCBs and trans-nonachlor over Lake Michigan has been constructed and the resulting data examined for trends. In this paper, we describe the model results to show how the magnitude and variability of a plume of contaminants from the Chicago area contributes to a highly variable region of net contaminant deposition over the entire lake. For the whole lake, gross annual deposition of PCBs is ∼ 3200 kg, although the net annual gas exchange is not significantly different from zero. The data-driven model illustrates that on a daily basis, the net exchange of persistent organic pollutants (POPs) can change from net deposition to net volatilization depending on the area of plume impact. These findings suggest that i) control of urban areas can accelerate the rate of volatilization from lakes; and ii) release of POPs from urban areas is largely a result of volatilization processes.

The transport of organic and inorganic material in 10 Norwegian rivers has been monitored from 1990 to 1998. The suspended material in the rivers consisted of 40–80% organic materials. A major part of this was DOC with a C/N mole ratio > 25. The C/N ratio of the organic material increases with increasing river flow when drained from forest-dominated catchments, in contrast to mountain dominated catchments where variation in runoff does not influence the C/N ratio. Laboratory experiments showed that more than 90% of the DOC remained in solution when salinity increased to 30. The flocculated and settled material contained less than 5% organic material with a C/N ratio of 6.7–12.4, comparable to C/N ratios in cultivated soils and coastal marine sediments. This confirms that only a minor amount of organic material carried to the sea by rivers settles in the coastal zone.

Transformation in Polish agriculture initiated by political changes in the 1990s brought about essential variations in the structure of agricultural land use. The share of cereals in cropping patterns increased, while fodder plants decreased. In addition, the level of mineral fertilization was reduced. In livestock production animal stock showed a sharp fall, which led to a decreased load of organic fertilization. The changes in cropping pattern and lower fertilization rates resulted in a decrease in the organic matter level in soils, which may impair soil quality status. These phenomena were strongly manifested in the Wielkopolska Region mainly because of the prevalence of light soils in this area, from which nutrients are readily washed out to groundwaters. It was found that many of the negative aspects of these changes in the agricultural landscape can be mitigated by establishing shelterbelts. We conclude that shelterbeds are especially effective in the control of nutrient output from a watershed.

Alachlor, metolachlor and their respective environmentally stable aniline degradation products, 2,6-diethylaniline and 2-ethyl-6-methylaniline were analyzed in water and sediment samples from 9 sites along River Nzoia, Kenya using gas chromatography. The degradation products were detected in > 90% of the sediment and water samples, while the parent compounds occurred in < 14% of the water samples. Much higher concentrations of the pesticides and their degradation products occurred in the sediment than in the water (1.4 up to 10 800-fold), indicating an accumulation of the compounds in the sediment. The constant occurrence of the degradation products in the sediment during the study period infers a persistence of these compounds. It is hypothesized that the prevailing tropical climatic conditions favor a quick breakdown of the pesticides to their environmentally stable degradation products, thereby making the latter more important pollutants than their parent products in the study area.

Both frequency and intensity of disturbances in many ecosystems have been greatly enhanced by increasing human activities. As a consequence, the short-lived plant species including many exotics might have been dramatically increased in terms of both richness and abundance on our planet, while many long-lived species might have been lost. Such conclusions can be drawn from broadly observed successional cycles in both theoretical and empirical studies. This article discusses 2 major issues that have been largely overlooked in current ecosystem management policies and conservation efforts: i) life history constraints; and ii) future global warming trends. It also addresses the importance of these 2 factors in balancing disturbance frequency and intensity for optimal biodiversity maintenance and ecosystem management.