The abiotic factor that is essential for all aquatic ecosystem with the exception of hydro thermal vent is SUNLIGHT, THIS IS BECAUSE IT PROVIDES A SOURCE OF ENERGY.
Sunlight is very essential for aquatic ecosystems because it is the principal source of energy from which aquatic plants trap energy to make their food and provided mean of sustenance for themselves and other organisms in the water.
The comparison and contrast between the raft and the shore has something to do with freedom. On the river, Huck and Jim are free from the legal, societal and cultural structures which is the opposite if they were on the shore. However, their freedom on the raft was only for a short period of time. When<span> they went back on the shore, they were once again forced to comply with the </span>laws. The<span> similarities between the raft and the shore </span>are<span> natural. They are both are connected with geographical features.</span><span> </span>