T52 High-Resolution Geochemical Proxies of Global Change: Progress, Problems, and Utility (Posters)

Sunday, 19 October 2014
9:00 AM - 5:00 PM
Exhibition Hall C

PRELIMINARY GROWTH AND TRACE ELEMENTAL CHARACTERIZATION OF RHODOLITHS (LITHOTHAMNION SP.) FROM THE GULF OF PANAMA, PANAMA

Paper number: T52-7
Program: Technical Sessions
Time: 9:00 AM – 5:00 PM

Authors

Abstract

Rhodoliths, free-living forms of coralline red algae, are an important proxy resource for understanding short and long-term environmental trends in tropical to arctic oceans. Coralline algae produce accretionary, high-Mg skeletons which contain no ontogenetic growth trends, thus permitting the measurement of time series elemental data profiles that may serve as useful proxies for a range of environmental variables. Tropical rhodoliths (n=196) of the Lithothamnion sp. were collected near the southern extent of the Archipelago de Las Perlas, Gulf of Panama via SCUBA diving to test how elemental uptake changes with altered conditions in pH and other environmental parameters related to skeletal growth. For the total sample population, rhodoliths were highly branched and classified as predominantly spheroidal (30.61%) and spheroidal-discoidal (29.08%) with the remaining 40.31% falling into variable categories of spheroidal-ellipsoidal according to the Sneed and Folk (1958) classification scheme. Sizes ranged from 1.5-6.65 cm and average wet weight was 14.4 g. Alizarin Red S (ARS) stain was used to study growth rates for 60 samples randomly selected for mesocosm experiments. Algal growth post-ARS has offered insight into growth rates, sample age, and increment periodicities. To date, samples PRE-028 and PRE-006 have been measured with growth rates of 1.92 µm d-1 and 1.95 µm d-1, respectively, and total sample ages of ca. 13.4 yrs BP and 16.0 yrs BP. Initial tests using LA-ICP-MS indicate that measurable trace elemental patterns (e.g. P and Mn) are present and were analyzed to assess potential environmental variations.