QUALITATIVE AND QUANTITATIVE OBSERVATIONS ON AQUATIC ALGAL COMMUNITIES AND RECOLONIZATION WITHIN THE BLAST ZONE OF MT. ST. HELENS, 1980 AND 19811

Abstract

ABSTRACTDespite the destruction and total rearrangement of much of the area north of Mt St. Helens, many different species of algae became established in the aquatic systems located in the blast zone within 3–4 months after the eruption of May 18, 1980. Initial sites of intense algal activity were found in benthic regions associated with warm springs and in the littoral and phytoplanktonic communities of some small lakes. In the summers of 1980–81, overall phytoplankton numbers and activity were low in the large lakes closest to the crater (e.g. Spirit Lake). However, diatoms, blue‐green and green algal isolates from these lakes were obtained in laboratory cultures on a reduced inorganic medium used to enumerate metal and sulfur oxidizing bacteria. Species of Nodularia, Pseudanabaena, Anabaena, Oscillatoria, Nitzschia, Tribonema, Chlamydomonas, Chlorella, and microflagellates (predominantly cryptomonads) were among the more common forms found in preserved samples or isolated in cultures.