As complementary to the previous project, here I described a higher-level habitat cascade, again in soft-bottom estuarine communities, testing how a higher order habitat cascade affects client diversity. Here, the primary habitat former was again a bivalve while both the secondary and tertiary habitat formers were seaweeds but different in species and morphologically features (see previous project). To date, there are only two cases of ‘long habitat cascades’ described but I believe that they are common and widespread even if not enough investigated.
In this study I hypothesized the existence of a 4-level habitat cascade based on the successive interaction between the bivalve Austrovenus stutchburyi, the green seaweed Ulva sp. and the red seaweed Gracilaria chilensis, testing the following hypothesis:
(1) the 4-level habitat cascade is more stable than the corresponding 3-level one previously described (Austrovenus–Gracilaria-invertebrates), i.e., it supports larger abundance and richness of invertebrates as a result of a more structurally complex interaction;
(2) this condition is consistent across season, with more noticeable effects in summer;
(3) the contribution of Ulva as 3rd habitat former is relevant across latitudes, with stronger effects in northern regions, irrespective of the condition of the second habitat former (here, artificial mimic);
(4) similar effects are reported when the habitat formers are non-living (here, artificial mimic), as a result of the contribution of Ulva’s mimics to the morphological features of the habitat cascade.