3 resultados para Women and literature - Italy - History - 20th century
em DigitalCommons@University of Nebraska - Lincoln
Resumo:
North Pacific right whales (Eubalaena japonica) were extensively exploited in the 19th century, and their recovery was further retarded (severely so in the eastern population) by illegal Soviet catches in the 20th century, primarily in the 1960s. Monthly plots of right whale sightings and catches from both the 19th and 20th centuries are provided, using data summarized by Scarff (1991, from the whale charts of Matthew Fontaine Maury) and Brownell et al. (2001), respectively. Right whales had an extensive offshore distribution in the 19th century, and were common in areas (such as the Gulf of Alaska and Sea of Japan) where few or no right whales occur today. Seasonal movements of right whales are apparent in the data, although to some extent these reflect survey and whaling effort. That said, these seasonal movements indicate a general northward migration in spring from lower latitudes, and major concentrations above 40°N in summer. Sightings diminished and occurred further south in autumn, and few animals were recorded anywhere in winter. These north-south migratory movements support the hypothesis of two largely discrete populations of right whales in the eastern and western North Pacific. Overall, these analyses confirm that the size and range of the right whale population is now considerably diminished in the North Pacific relative to the situation during the peak period of whaling for this species in the 19th century. For management purposes, new surveys are urgently required to establish the present distribution of this species; existing data suggest that the Bering Sea, the Gulf of Alaska, the Okhotsk Sea, the Kuril Islands and the coast of Kamchatka are the areas with the greatest likelihood of finding right whales today.
Resumo:
ABSTRACT This thesis will determine if there is a discrepancy between how literature defines conservation, preservation, and restoration, and how natural resource professionals define these terms. Interviews were conducted with six professionals from six different agencies that deal with natural resources. These agencies consisted of both government and non-government groups. In addition to interviewing these professionals regarding how they define the terms, they were asked where their work fits into the context of these terms. The interviewees’ responses were then compared with the literature to determine inconsistencies with the use of these terms in the literature and real world settings. The literature and the interviewees have agreed on the term conservation. There are some different points of view about preservation, some see it as ‘no management’ and some others see it as keeping things the same or ‘static.’ Restoration was the term where both the literature and professionals thought of moving an ecosystem from one point of succession or community, to another point on a continuum. The only thing in which they disagree on is the final goal of a restoration project. The literature would suggest restoring the ecosystem to a past historic condition, where the interviewees said to restore it to the best of their abilities and to a functioning ecosystem.
Resumo:
White Rock Lake reservoir in Dallas, Texas contains a 150-cm sediment record of silty clay that documents land-use changes since its construction in 1912. Pollen analysis corroborates historical evidence that between 1912 and 1950 the watershed was primarily agricultural. Land disturbance by plowing coupled with strong and variable spring precipitation caused large amounts of sediment to enter the lake during this period. Diatoms were not preserved at this time probably because of low productivity compared to diatom dissolution by warm, alkaline water prior to burial in the sediments. After 1956, the watershed became progressively urbanized. Erosion decreased, land stabilized, and pollen of riparian trees increased as the lake water became somewhat less turbid. By 1986 the sediment record indicates that diatom productivity had increased beyond rates of diatom destruction. Neither increased nutrients nor reduced pesticides can account for increased diatom productivity, but grain size studies imply that before 1986 diatoms were light limited by high levels of turbidity. This study documents how reservoirs may relate to land-use practices and how watershed management could extend reservoir life and improve water quality.