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On Earth Day of this year, the British Petroleum-operated Deepwater Horizon oil drilling rig exploded in the Gulf of Mexico, 41 miles off the Louisiana coast. The blast killed 11 workers, injured 17, launched a massive oil spill, and triggered an environmental catastrophe—the full impact of which may not be realized for years.
We used rates of ingested shot and elevated blood-lead levels (≥0.18 ppm) to estimate the proportion of Canada geese (Branta canadensis) exposed to lead on 3 study areas in Manitoba, Minnesota, and Missouri. Lead exposure was prevalent on all areas and was common after the hunting season closed, when up to 15% of geese could have been exposed to lead shot. However, the proportion of steel shot ingested by geese has increased during the past 2 decades. We suggest that lead exposure is still a source of indirect hunting mortality in Canada geese but project that the prevalence of lead exposure in the Eastern Prairie Population and other waterfowl populations will decrease as nontoxic shot regulations persist and hunters use steel or other nontoxic shot.
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The problem of controlling the sea lamprey in the upper Great Lakes has received considerable attention in recent years and requires no review here (Applegate and Moffett. 1955). Electromechanical weirs and traps and electrical barriers have been developed which can be successfully employed to block and/or destroy spawning runs of adult sea lampreys. These devices. when installed in all known $pawning streams. provide an effective method of reducing the numbers of sea lampreys in each lake basin. Initial efforts at control of the lamprey have employed these devices (Applegate. Smith. and Nielsen. 1952; Erkkila. Smith. and McLain. 1956).
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Automated opaque flux-chamber measurements of soil carbon dioxide (CO 2 ) flux (soil respiration) into the atmosphere at the Amargosa Desert Research Site show seasonal and diel cycles of soil respiration that are closely linked with soil temperature and soil moisture. During 1998, soil respiration increased with soil warming through spring, reaching a maximum rate (not counting anomalously high values scattered through the record) of about 0.055 moles CO 2 m -2 day -1 around Julian Day 120. Respiration rates then declined along with volumetric soil moisture content, tending to stay at or below about 0.02 moles CO 2 per square meter per day (m -2 day -1 ) for the rest of the year, except after summer rainfalls when respiration sharply increased for short periods. The diel respiration pattern during dry spells is marked by a sharp rise in CO 2 flux coincident with steeply rising soil temperatures in the morning, then dropping back to low levels about the time of maximum soil temperature. The reason for this pattern in unclear.