Comparison of the Polychaetous Annelids Populations on Suspended Test Panels in Los Angeles Harbor in 1950-1951 with the Populations in 2013-2014

Abstract

A 14-month study was conducted of the polychaetous annelids present on attached wooden blocks at nine stations in Los Angeles Harbor in 2013-2014. The results were compared to a similar study conducted at the same stations in 1950-1951. The primary objective in both studies was to determine the location and occurrence of marine borers in the harbor. Since fouling organisms, including polychaetes, attached to the wooden blocks, it also provided an opportunity to study the polychaetes that settled on the blocks. The number of polychaete species in these two studies increased from 22 to 71. The serpulid Hydroides elegans was a dominate species in both studies but the pollution indicator Capitella capitata, common in the earlier study, was rare in the recent study. There was a seasonal occurrence in both the number of species and specimens with highs in the warmer months and lows from December through March in both studies. Many environmental changes have occurred in the Los Angeles Harbor complex over the past 63 years. New harbor piers constructed that extend into the Outer Harbor, channels have been dredged deeper and pollution abatement programs initiated. The water quality has been improved especially in the Inner Harbor as a result of these changes where the dissolved oxygen in the water was low or absent in 1950-1951 but higher (over 6.0 mg/L) in 2013-2014. This study is unusual since long-term, seasonal comparisons of marine invertebrate populations are uncommon.