Pilot and Special Studies

Understanding the Relative Sensitivity of Terns to PBDEs

Authors: Barnett Rattner (USGS)

San Francisco Bay is critical habitat for many birds including several rare and endangered species such as the Least Tern. Some of the highest polybrominanted diphenyl ether (PBDEs) concentrations identified to date have been measured in Bay Area Caspian, Least and Forster’s terns. At present, we have very little information to determine whether these concentrations are causing significant effects.

Recent research by the USGS Patuxent Wildlife Research Center suggests that significant effects on the hatching success of American Kestrels can occur at injected concentrations as low as 1.8 ug/g (wet weight). In contrast, mallards were relatively insensitive to exposure to PBDEs. A number of uncertainties exist with these studies as they are egg injection studies rather than a maternally-derived exposure. Nonetheless, maximum concentrations in tern eggs from the Lower San Francisco Bay are in the range of the injected concentrations that elicit effects.

This egg injection study will determine the sensitivity of terns to PBDEs as measured by the hatching, pipping, and survival of the east coast common tern, a surrogate for the San Francisco Bay area Least, Caspian and Forster’s terns. It will also evaluate the terns for sublethal effects such as deformities, growth, hepatic, thyroid and immune organ histopathology, and biochemical effects.

Sediment Quality Objectives

Authors: Aroon Melwani and Sarah Lowe (SFEI)

In 2009, the State of California adopted Sediment Quality Objectives that incorporate multiple lines of evidence to assess the health of the Estuary’s sediment (i.e., sediment chemistry, sediment toxicity and benthos). At that same time, the RMP began monitoring benthos to provide all three lines of evidence to assess the sediment quality of the Estuary.

Although SQO for bays and estuaries have been adopted, staff from the RMP, SCCWRP, the State Water Resources Control Board, Regional Water Quality Control Board, the USGS, and Department of Water Resources have been meeting to determine how additional SQO assessments will be conducted. The RMP has convened a number of benthic workshops to discuss the development of benthic indices for the oligohaline (freshwater) and mesohaline (moderately saline) portions of the Estuary.

In 2009, the RMP began revising the mesohaline benthic tools for San Francisco Bay. A standardized benthic dataset for San Francisco Bay was reviewed, classification analysis of benthic assemblage data has now been performed; and a best professional judgment exercise commenced. The results of the best professional judgment exercise will be completed in late 2009.

In 2010, we will complete the mesohaline index for the Estuary and develop a chemical score index for San Francisco Bay (a correlation between chemistry and benthos). At present, the chemical score index has been developed for Southern California and it has a poor correlation for San Francisco Bay.

Developing Land Use Classification Scheme for Monitoring

Authors: Lester McKee (SFEI)

A critical need for prioritizing watersheds to monitor and model is an evaluation of land use characteristics that influence stormwater loads to the Estuary. Eight land use types have been identified as important for Southern California...