Benthic Invertebrates as Indicators of Marine Pollution: 35 Years of Study

Los Angeles-Long Beach Harbors were a grossly polluted body of water at the time of initiation of benthic invertebrate studies in 1951. Waste discharges included industrial, domestic and storm waters which received little or no treatment. The inner harbor water mass contained little or no dissolved oxygen, but the outer harbor was well oxygenated. Benthic conditions were characterized by four different associations of animals plus an azoic zone. A pollution abatement program was initiated in 1968 and has continued to this day. Waste discharges were either eliminated or diverted to treatment plants. The effects of this abatement program were noted shortly thereafter and had a dramatic effect on the benthic fauna. The azoic and polluted zones were repopulated and are now characterized by a rich, varied benthic fauna. Benthic species known only previously from offshore areas are now resident inhabitants of the outer harbor. The usefulness of benthic monitoring over the past 35 years has demonstrated the rapidity of the improvement of ecological conditions as a result of pollution abatement. Furthermore, the knowledge gained from 35 years of study has provided a valuable data base as future changes in the harbor are contemplated.