Variation in concentrations of trace elements in otoliths and eye lenses of a temperate reef fish, Parma microlepis, as a function of depth, spatial scale, and age

Territorial Parma microlepis (Gunther) (Pomacentridae) were collected at di fferent depths, at three sites in each of four estuaries near Sydney, Austr alia. Element concentrations were measured by inductively-coupled-plasma ma ss spectrometry. Significant differences in concentrations of Mn and Ba wer e found in the otoliths of fish sampled in different depth strata, with con centrations generally greatest: in fish found in water <4 m deep. Depth-rel ated differences varied among estuaries (e.g. 0 to 1.2 <mu>g Ba g(-1) otoli th). In most estuaries there was a negative linear relationship between con centrations of Mn and Ba in otoliths and actual depth. Great variation was found within an estuary among sites separated by 0.5 to 3 kin. In the eye l enses, concentrations of Rb differed according to depth of capture of fish. The age of fish (li to 34 yr) had no influence on the concentrations of el ements in otoliths or lenses. Multivariate comparisons of elemental composi tion (= fingerprints) detected significant differences among depth strata. Fish collected from shallow water had the clearest multivariate classificat ion according to depth. There was a close match between our shallow strata and the average depths reached by low-salinity/high-temperature estuarine p lumes. The element composition of whole otoliths and lenses represents aver age concentrations experienced by the fish. The temporal resolution of diff erences in ambient conditions is likely to be coarse in the fish (i.e. mont hs to years).