Comparison of the Marine Wood Borer Populations in Los Angeles Harbor in 1950-1951 with the Same Populations in 2013-2014
Reish, Donald J.
Gerlinger, Thomas V.
Ware, Robert R.
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A 14 month study was conducted of the marine wood borers present on monthly suspended wooden blocks at nine stations in Los Angeles Harbor in 2013-2014, and compared to the results of a marine borer study conducted in 1950-1951. Many environmental changes have occurred in the harbor over the past 60+ years. The harbor land mass of the outer harbor has been expanded towards the breakwater, channels were deepened, and the water quality improved as a result of pollution abatement. Existing pilings were removed, replaced or covered with two layers of polyethylene. The isopod Limnoria tripunctata and the pelecypod Lyrodus pedicellatus were the principal species and present at nearly all stations. Station C located in the Consolidated Slip area of the inner harbor was the site of 87 and 58 percent of the Limnoria and Lyrodus, respectively, counted during the study. Neither of these species was present at this station in 1950-1951. The dissolved oxygen concentration at this station improved from a mean of 0.1 ppm in 1950-1951 to a mean of 6.7 in 2013-2014 as a result of improved environmental conditions. Larval settlement at Station D numbered in the thousands in 1950-1951 but only 22 were counted during the 2013-2014 survey. This difference was attributed to the effect of piling covering or removal. It is recommended that existing creosoted pilings be covered or removed in the inner harbor area since this was the region of greatest occurrence of wood borers in 2013-2014.