Barnacles and mussels are filter feeders that attach themselves to rocks in the ocean. They eat by filtering small particles of food from the ocean water as it flows over them. A scientist observed a dense colony of barnacles covering the surface of a rock. The mussels were only able to attach to a few, small crevices on the same rock. Evaluate this observation and explain a limiting factor that is affecting the barnacles and mussels on the ocean rock.

For the strategies below, decide whether they are best described as demand-side solutions or supply-side solutions to meeting human needs for fresh water. remember that a demand-side solution reduces demand for fresh water, whereas a supply-side solution increases the supply of fresh water. (a) damming a river to create a reservoir (b) desalinating seawater (c) a nation invading a neighboring country to access their rivers (d) raising water prices for consumers and businesses (e) providing tax breaks for companies that use less water (f) replacing inefficient irrigation with more-efficient drip irrigation to grow crops (g) requiring low-flow showerheads in all new homes