Biology 2483A Lecture 2: Lecture 2 - The Physical Environment

• School: Western University
• Department: Biology
• Course: Biology 2483A
• Professor: Hugh Henry

Document Summary

Potential causes of salmon declines in the north pacific ocean: dam construction, sediment from logging operations, water pollution, overharvesting. But the conditions of oceans, where salmon spend most time as adults, have also been implicated. Hare and francis (1994) studied fish harvest records and showed alternating periods of high and low production associated with climatic variation in the north pacific. Mantua et al. (1997): periods of high salmon production in alaska corresponded with periods of low production in oregon and washington. They also found a correlation between salmon production shifts and sea surface temperatures. The physical environment ultimately determines where organisms can live, and the resources that are available. Thus, understanding the physical environment is key to understanding all ecological phenomena. Weather: current conditions temperature, precipitation, humidity, cloud cover. Climate: long-term description of weather, based on averages and variation measured over decades. Climatic variation includes daily and seasonal cycles, as well as yearly and decadal cycles.