Coexistence in Cold Waters: Animal Forests in Seaweed-Dominated Habitats in Southern High-Latitudes

Abstract

Coexistence between species plays an important role in structuring marine benthic communities but is often underestimated in current ecological studies. In the cold-water ecosystem, such as Chilean fjord/channels and Antarctic areas, animal forests are dominant on rocky substrates and exist among dense macroalgal forests as well as encrusting coralline algae. The distribution patterns of both animal and macroalgal forests are influenced by the topography of the rocky wall, where animal forests formed by trees- and mound-like growth forms become dominant with an increasing degree of inclination. The macroalgal forest tends to decrease from the inclined toward the overhanging profile. Along a latitudinal gradient, very abundant gregarious animal forests (e.g., mytilids ) on the subantarctic shallow rocky substrate tend to decrease in their abundance and distribution toward the rocky substrate of the Antarctic shallow areas. A contrasting pattern emerges regarding clonal animal forests (e.g., sponges), where dense assemblages of clonal growth forms are dominant in the Antarctic rocky substrate and tend to decrease toward the southern tip of South America. In both the Chilean fjord and channels and Antarctic ecosystems, the animal forests are key elements in the seascape as they have great potential as a tourist attraction and also provide important ecosystem services.