Effects of a surfacing effluent plume on a coastal phytoplankton community
KAUST DepartmentRed Sea Research Center (RSRC)
Biological and Environmental Sciences and Engineering (BESE) Division
Marine Science Program
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AbstractUrban runoff and effluent discharge from heavily populated coastal areas can negatively impact water quality, beneficial uses, and coastal ecosystems. The planned release of treated wastewater (i.e. effluent) from the City of Los Angeles Hyperion Wastewater Treatment Plant, located in Playa del Rey, California, provided an opportunity to study the effects of an effluent discharge plume from its initial release until it could no longer be detected in the coastal ocean. Non-metric multi-dimensional scaling analysis of phytoplankton community structure revealed distinct community groups based on salinity, temperature, and CDOM concentration. Three dinoflagellates (Lingulodinium polyedrum, Cochlodinium sp., Akashiwo sanguinea) were dominant (together >50% abundance) prior to the diversion. Cochlodinium sp. became dominant (65-90% abundance) within newly surfaced wastewater, and A. sanguinea became dominant or co-dominant as the effluent plume aged and mixed with ambient coastal water. Localized blooms of Cochlodinium sp. and A. sanguinea (chlorophyll a up to 100mgm-3 and densities between 100 and 2000cellsmL-1) occurred 4-7 days after the diversion within the effluent plume. Although both Cochlodinium sp. and A. sanguinea have been occasionally reported from California waters, blooms of these species have only recently been observed along the California coast. Our work supports the hypothesis that effluent and urban runoff discharge can stimulate certain dinoflagellate blooms. All three dinoflagellates have similar ecophysiological characteristics; however, small differences in morphology, nutrient preferences, and environmental requirements may explain the shift in dinoflagellate composition. © 2013 Elsevier Ltd.
SponsorsThe authors thank the City of Los Angeles Environmental Monitoring Division for providing logistical support, ship time, and ship crew. We also thank the captains and crew of the MV Marine Surveyor and the RV Sea World. The City of Los Angeles (M. Dojiri, B. Brantley), USC (D. Caron, A. Schnetzer, Z. Zheng), SCCWRP (D. Diehl), NASA JPL (B. Holt), and UCSD (E. Terrill) were involved in the planning, implementation, field component, and sample/data processing of this project. Lastly, we would like to thank two anonymous reviewers for their comments and suggestions. This work was supported in part by a NASA Oceans & Ice Research Project Award (NRA-04-OES-02), through the NASA Earth Systems Science Fellowship Program (NNX06AF70H), and through USC Sea Grant.
JournalContinental Shelf Research