Multivariate Analysis of Sediment Toxicity in an Ocean Ecosystem: A Southern California Bight Case Study

Contaminated sediments can negatively affect aquatic organisms and beneficial uses of coastal regions. Monitoring programs typically collect many indicators of sediment toxicity, yet multivariate approaches that comprehensively evaluate data across heterogeneous spatial environments are frequently not performed. In this paper, we explore a multivariate approach to show that a list of suspected drivers of sediment toxicity to native Mytilus galloprovincialis (mussel) and Eohaustorius estuarius (a marine amphipod) population can be narrowed down without excluding samples, and that redundancies in sampling sites can be identified and isolated. Using a 153 × 28 data matrix assembled from a southern California-wide bight monitoring program, we demonstrate by this approach that Port of Los Angeles (PLA) and San Diego Bay (SDB) contained the most toxic sediments in the bight in 2008, the nature of which was unique to each locality. (Note: Little toxicity was observed here in 2013 and 2018.) In PLA sediments, mussels were more affected than amphipods, with higher survivability associated with low Hg and Sn levels. Conversely, amphipods had higher mortality than mussel embryos in SDB sediments, with higher survivability associated with low Be and Co levels. Nitrogen, organic content, and finer sediment particles were not related to the survivability of these organisms.