Succession of benthic hard-bottom communities in the shallow sublitoral of Comau Fjord, Chile

Succession was already studied over decades. The present thesis investigated the succession on hard substrate at two different study sites within the fjord Comau, Chile. Nine plates were installed at both sites (mouth of fjord and inner fjord) and photographed over three years. Additionally the natural community was recorded and a ground truthing was carried out to verify the analyzed species. Respectively at both sites over 50 different species were identified. Abundance data decreased with only one exception continuously, whereas the percentage cover increased. But the communities on the recruitment plates do still not reach the community structure of the natural environment. The present data showed that the hard-bottom succession in the fjord Comau is best described by the TOLERANCE MODEL (Connell & Slatyer, 1977). An important species of the natural community is the stony coral Desmophyllum dianthus, which normally (outside the fjord) grows beneath 1000 m water depth. The results of this work indicate that the mature community is not reached after 36 months.

Biology community and bottom sediments in the West Bay of the Furugelm Island, Sea of Japan

An experiment was carried out on the soft bottom in the sublitoral zone of the Furugelm Island (Peter the Great Bay, Sea of Japan) to study formation of benthic communities. Boxes with defauned sediments were placed on depths of 4, 6 and 13 m and exposed during 60 days in the summer period. Half of them were covered with a net with mesh size 2 cm to prevent effect of large predators. It was found that spatial pattern of invertebrates' sinking in the bay conforms to distribution of benthic communities. Larvae of benthic invertebrates sinks in general in places inhabited by their adult species. The main factors responsible for recolonzation are: sediment type and local hydrodynamic conditions. Heart-shaped sea urchin Echinocardium cordatum is numerically dominated in the bay on depth 3-4.5 m, but its larvae sinks in the deeper area. Community structure is supported by mature specimen migration to places inhabited by species. Predators affect largely on the species.