Final answer:
Commercially valuable fish and shellfish spend parts of their life cycles in estuaries and coastal water habitats, with areas like bivalve beds being crucial for growth. The Pacific oyster, a key aquaculture species, has also become invasive in new environments, impacting local ecosystems.
Step-by-step explanation:
Many commercially valuable fish and shellfish spend a portion of their life cycle in estuaries and coastal water habitats, such as bivalve beds, mudflats, and mussel beds. These areas provide critical environments for the growth and development of various marine species. For example, the Pacific oyster (Crassostrea gigas) is known for its high growth rates and reproductive output, making it a prominent species in aquaculture. Additionally, estuaries serve as important feeding grounds for larger predatory fish that are also commercially fished. However, the introduction of species like the Pacific oyster to new environments has led to it becoming an invasive species, affecting local ecosystems and native species. The introduction of species across regions, often for aquaculture purposes, can create ecological changes, leading to potential problems such as the depletion of native species and alterations in the food web structure.