Field Evidence of Metal Transfer from Invertebrate Prey to an Intertidal Predator, Thais clavigera (Gastropoda: Muricidae)

Dissolved and particulate organic matter were studied in northern San Francisco Bay estuary on seven dates from April to October 1996 when flow from the Sacramento and San Joaquin river Delta was declining. Measurements were made at three to 11 stations (usually eight) along the salinity gradient from the Sacramento River to the Central Bay. Dissolved constituents included monosaccharides (MONO), total carbohydrates (TCHO), dissolved primary amines (DPA), dissolved organic carbon (DOC), and the fluorescence of humic substances (HF). Particulate constituents included bulk suspended particulate matter (SPM), chlorophyll a (CHL), particulate organic carbon (POC) and particulate organic nitrogen (PON). April was distinct from subsequent months due to very high DOC and MONO concentrations and somewhat elevated TCHO, DPA and HF concentrations. DOC, MONO, TCHO and HF concentrations generally decreased with increasing salinity suggesting an upper estuarine source of these constituents. In contrast, DPA had a bimodal distribution suggesting both upper and lower estuarine sources. There was evidence of a persistent, additional source of organic matter near Suisun Bay that was high in DOC and HF, but low in DPA. It was speculated that this material originated from one or more of the following: (a) the San Joaquin River, (b) exchange with the shoals and intertidal reaches of Suisun Bay, and (c) flux of DOC from particulate organic matter (POM). The particulate organic constituents, POC and PON, strongly correlated with SPM but not with CHL, suggesting that sediments were relatively important and phytoplankton were relatively unimportant contributors to POM pools.