Based on the observation that faunal assemblages vary with depth and composition of sediments varies with depth, it can be proposed that differences in
composition of sediments cause the difference in assemblages. Therefore, a
relevant hypothesis is that, for any particular composition of sediments, similar
fauna will be found at all depths. Also, at any depth, the fauna in a particular
type of sediment will be similar to that in the same type of sediment at other
depths.
(ii) Given previous observations of fewer amphipods in areas where rays feed, the
model can be proposed that predation or disturbance by the rays decreases
the number of amphipods. This leads to the hypothesis that areas where rays
are experimentally prevented from entering will develop larger numbers of
amphipods than in corresponding control areas.