Final answer:
The primary sector in Atlantic Canada faces decline due to the collapse of the cod fisheries, primarily caused by overfishing. This decline directly impacts the economy and environment, with repercussions throughout the food web.
Step-by-step explanation:
The primary sector has been decreasing in Atlantic Canada due to the collapse of cod fisheries. The primary sector includes industries such as agriculture, mining, forestry, and fishing. Therefore, when the cod population suffered a collapse primarily due to overfishing, those working within this sector found their livelihoods at risk as the natural resource they depended upon became scarce.
A software developer, however, would be categorized in the quaternary sector of the economy, which involves knowledge-based activities, often dealing with information technology, consulting, and research.
The collapse of the cod population due to overfishing is a critical environmental and economic issue. Ecosystems can be dramatically affected, as tertiary consumers (top predators in the food web) would die out due to lack of food, potentially leading to the collapse of the entire food web.