Final answer:
The elevated temperatures from the power plant would likely cause aquatic organisms to experience seasonal stress due to lower dissolved oxygen levels and the physiological impact of temperature on cold-blooded organisms.
Step-by-step explanation:
The construction of the Lake Anna by Dominion Virginia Power for the North Anna Nuclear Power Station has led to an increase in the lake's average water temperature by seven degrees compared to typical water temperatures in the area. The effect of this increase on aquatic organisms is multifaceted. The higher temperatures result in lowered dissolved oxygen levels due to the fact that warmer water holds less oxygen. During thermal stratification in the summer, there's a separation of water layers, preventing oxygen-rich surface water from mixing with deeper waters. Additionally, in the winter, although organisms can survive beneath the ice due to the water's density remaining liquid, the elevated temperatures from the power station's influence could still affect these organisms too. Most nonmammalian aquatic organisms are cold-blooded, and their physiology is directly affected by the surrounding water temperature. These elevated temperatures could lead to severe seasonal stress by affecting their metabolism, respiration, and overall health because enzymes, vital for metabolic processes, are efficient only within a narrow temperature range. Over time, these conditions can lead to a suffocation-like state for organisms that depend on dissolved oxygen, or force them into environments which fall outside of their optimal temperature range, causing stress or death. Therefore, the statement that aquatic organisms will thrive year-round is inaccurate, as is the notion that they will not be affected. The option suggesting that organism will migrate to warmer waters in winter does not apply since the water is already warmer due to the power station's operations. The most fitting answer is that aquatic organisms will experience seasonal stress due to fluctuations in water temperatures and the associated physiological and ecological consequences.