ISSN:1208-6053    

DOI:10.1139/erauthor99

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

The Great Lakes Herring Gull Monitoring Program has annually provided information concerning levels of environmental contaminants in herring gull eggs since 1974, making it one of the longest running biomonitoring programs in the world. The program was initiated in response to observations of poor reproductive success in colonial waterbirds on the Great Lakes.Initial studies examined the role of halogenated hydrocarbons (HAHs) in causing this reproductive dysfunction. By the late 1970s, reproductive success in herring gulls had improved greatly and emphasis was placed on developing more sensitive indicators to measure the subtle effects associated with HAH exposure. Geographic and temporal trends in Great Lakes contamination were also elucidated. Analysis of herring gull tissues led to the identification of HAHs (mirex, photomirex, polynuclear aromatic hydrocarbons, chlorobenzenes, dioxins) previously undetected in Great Lakes upper trophic level biota. Data collected as part of this program have improved our understanding of contaminant sources and fate in the Great Lakes and have provided us with a means to assess our progress in controlling contaminant inputs. The extensive nature of this dataset has allowed detailed examination of the factors that regulate contaminant levels in this species. Most monitoring programs rely on less extensive datasets for the interpretation of environmental trends and may benefit from the mechanisms identified here. Research has also identified other stressors, e.g., dietary deficiencies, that may affect the success ofGreat Lakes herring gull populations. Ongoing monitoring of this species will continue to provide new insights into the dynamic Great Lakes ecosystem.Key words: herring gull,Larus argentatus, Great Lakes, environmental monitoring,halogenated hydrocarbons, contaminants.

ISSN:1208-6053    

DOI:10.1139/a99-011

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

This paper approaches ecological data analysis from a different vantage point and has implications for ecological risk assessment. Despite all the advances in theoretical ecology over the past four decades and the huge amounts of data that have been collected in various marine monitoring programs, we still do not know enough about how marine ecosystems function to be able to make valid predictions of impacts before they occur, accurately assess ecosystem ``health,'' or perform valid risk assessments. Comparisons are made among the fields of psychology, social science, and ecology in terms of the applications of decision theory or approach to problem diagnosis. In all of these disciplines, researchers are dealing with phenomena whose mechanisms are poorly understood. One of the biggest impediments to the interpretation of ecological dataand the advancement of our understanding about ecosystem function is the desire of marine scientists and policy regulators to cling to the ritual of null hypothesis significance testing (NHST) with mechanical dichotomous decisions around a sacred 0.05 criterion. The paper is divided into three main sections: first, a brief overview of common misunderstandings aboutNHST; second, why diagnosis of ecosystem health is and will be such a difficult task; and finally, some suggestions about alternative approaches for ecologists to improve our "diagnostic accuracy'' by taking heed of lessons learned in the fields of clinical psychology and medical epidemiology.Key words: statistical significance, Bayesian statistics, risk assessment

ISSN:1208-6053    

DOI:10.1139/a99-014

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

A literature review is given of atmospheric trace metal concentrations in aerosols above the North Sea and the English Channel over the period 1971-1994. Literature data have been gathered and intercompared to look for possible trends in the reported concentrations. Six trace metals are considered: Cd, Cu, Pb, Zn, Ni, and Cr. A distinction is made between measurements in different regions of the North Sea, and between coastal and marine areas. The majority of the data deals with the Southern Bight, providing the most reliable trends. Strong decreasing trends are observed for the Pb and Zn concentrations above the North Sea during the years 1971-1994. For Cd, Cu, Ni, and Cr, much less data are available in the literature. Despite this, also for Cd and Cu a decreasing trend is present. Cr and Ni concentrations are fluctuating, mostly without a certain pattern. The trends in the concentrations are also compared to changes in the European emission profiles.Key words: heavy metals, aerosols, North Sea, trend analysis, literature.

ISSN:1208-6053    

DOI:10.1139/a99-012

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

A comprehensive review is presented of changes of PCB concentrations in aquatic biota collected from Lake Ontario between 1977 and 1993, with emphasis on data for lake trout. Results of three major lake trout surveys from Canadian and United States agencies indicate lake trout PCBs have declined from the early 1980s, but changes in recent years are masked by interannual variability. These results also apply to other biota in the aquatic food web. PCB concentrations were consistent among the surveys after consideration of fish lipid content, age or size and analytical protocol. Variability of 20 to 30% in annual average estimates is attributed to both analytical and in situ sources. Current levels of PCBs in many salmonids exceed PCB consumption and wildlife protection advisories. The average half-life for PCBs in Lake Ontario biota is about 12 years and it will take three to four times that to reach the International Joint Commission target of 100 ng/g (ww) for protection of wildlife. It is essential that the design of monitoring programs ensures consistent, coordinated sampling and analysis. A monitoring strategy of annual sampling of key species supplemented with periodic intensive sampling of the entire food web (e.g., every 5 years) is suggested as more effective than current practices. There is a frequently neglected need for fuller interpretation of contaminant dynamics based on complementary research on the nature of the changing biotic and abiotic environments in a complex aquatic ecosystem like Lake Ontario.Key words: Lake Ontario, PCBs, fish, food webs, monitoring data, bioaccumulation.

ISSN:1208-6053    

DOI:10.1139/a99-013

出版商:NRC Research Press    

年代:2000

数据来源: NRC