Michael Savarese

INFLUENCE OF SALINITY ON THE HABITAT USE OF OYSTER REEFS IN THREE SOUTHWEST FLORIDA ESTUARIES

Abstract To gauge the influence of salinity on the habitat value of oyster reefs, spatial and seasonal patterns of the presence of reef-resident fishes and decapods were assessed in the Caloosahatchee, Estero, and Faka-Union estuaries of Southwest Florida. Lift nets (1 m2) containing 5 L of oyster clusters were deployed on intertidal reefs at three sites along the salinity gradient of each estuary. Nets were deployed during three seasonally dry and three seasonally wet months for a period of 30 d. Oyster densities were estimated at each site and a number of community metrics were calculated as a measure of habitat use (e.g., organism density, biomass, diversity, dominance, richness). Several metrics increased downstream in one or more systems (e.g., organism density, biomass, diversity) and in general appeared to be more related to salinity than to the density of living oysters present. Although organism density was higher during the wet season for all three systems, biomass was higher during the dry season in the Caloosahatchee. In the Caloosahatchee and the Estero, measures of biodiversity tended to be higher during the dry season. These results suggest that the salinity requirements of the organisms that inhabit oyster reefs should be considered in the planning of oyster-reef restoration or enhancement projects or in the management or alteration of freshwater inflow into estuaries.

From Shell Midden to Midden-Mound: The Geoarchaeology of Mound Key, an Anthropogenic Island in Southwest Florida, USA.

Mound Key was once the capital of the Calusa Kingdom, a large Pre-Hispanic polity that controlled much of southern Florida. Mound Key, like other archaeological sites along the southwest Gulf Coast, is a large expanse of shell and other anthropogenic sediments. The challenges that these sites pose are largely due to the size and areal extent of the deposits, some of which begin up to a meter below and exceed nine meters above modern sea levels. Additionally, the complex depositional sequences at these sites present difficulties in determining their chronology. Here, we examine the development of Mound Key as an anthropogenic island through systematic coring of the deposits, excavations, and intensive radiocarbon dating. The resulting data, which include the reversals of radiocarbon dates from cores and dates from mound-top features, lend insight into the temporality of site formation. We use these insights to discuss the nature and scale of human activities that worked to form this large island in the context of its dynamic, environmental setting. We present the case that deposits within Mound Key’s central area accumulated through complex processes that represent a diversity of human action including midden accumulation and the redeposition of older sediments as mound fill.

Near-Surface Imaging (GPR) of Biogenic Structures in Siliciclastic, Carbonate, and Gypsum Dunes

High-resolution geophysical methods, such as ground-penetrating radar (GPR) imaging, are increasingly applied to ichnological research. Large vertebrate and invertebrate burrows and tracks can be detected and resolved using center frequencies of > 400 MHz. Geophysical images of bioturbation structures in siliciclastic, carbonate, and evaporite (gypsum) dunes exhibit characteristic electromagnetic signal returns, which are associated with active burrow openings (ground–wave gap), filled burrows (hyperbolic diffraction and “pull up”), and large tracks (concave up patterns). The noninvasive imaging can be used for pseudo-3D visualization (closely spaced survey lines) and monitoring of biogenic activity (repeated surveys). Because biogenic structures induce distinct anomalies in geophysical records collected at frequencies typical of many geological investigations, caution must be taken to avoid misinterpreting them as primary sedimentary structures.

The Stellate Burrow: A Large and Complex Trace Fossil in Holocene Carbonate Eolianites of the Bahamas

abstract Large, complex burrows, informally referred to as stellate burrows, are present in eolianites of windward sea-cliff exposures facing Exuma Sound on Moriah Harbour Cay (Exumas, Bahamas). These cliffs consist of limestones (age <1,800 years before present) assigned to the Hanna Bay Member of the Rice Bay Formation and comprise three progradational lithofacies of foreshore, backshore, and dune deposits. Upper foreshore and backshore beds contain well-preserved specimens of Psilonichnus upsilon, fossil burrows of the ghost crab Ocypode quadrata. The overlying eolianites exhibit typical physical sedimentary structures characteristic of coastal dunes, with the most striking feature being the abundant presence of stellate burrows consisting of a central shaft (∼3 to 7 cm diameter) and numerous upward-directed branches (∼1 cm diameter) with smooth, unlined walls that form a radiate pattern in cross section. Parallel central shafts commonly join at the base, forming distinctive U-shaped structures that reach total heights of >1 m. Other examples exhibit an irregular arrangement of shafts that merge to form exceptionally large and architecturally complex structures. The result is a distinctive ichnofabric reaching levels of 3 or more on the Droser-Bottjer Ichnofabric Index scale. The presence of abundant stellate burrows can result in a significant increase in porosity and permeability within host eolianites. Previously, stellate burrows were assigned to the ichnogenus Cellicalichnus, with origin attributed to burrowing and brooding activity of halictid (sweat) bees, common today in the Bahamas. Nonetheless, diagnostic cell structures are not present, and there are other important differences between stellate burrows and the previously described ichnospecies of Cellicalichnus. Other tracemaker possibilities are considered and evaluated, but firm identification of the tracemaker for the stellate burrows remains to be resolved.

Effectively Connecting Conservation Paleobiological Research to Environmental Management: Examples from Greater Everglades’ Restoration of Southwest Florida

Much of the research accomplished by paleontologists can be categorized as conservation paleobiology. Unfortunately, these works often go unrealized or under-appreciated because the environmental professionals best positioned to use those results are detached from the science, as managers or decision-makers, or are completely unaware of the scientific discipline. Commonly, a research program with management implications is undertaken without briefing the relevant agencies in advance and without their input with respect to research objectives and design. Academics typically work within or among their academic institutions with a predestined pathway toward peer-review publication in scholarly journals. Those papers often go unread by agency professionals, and universities at times of promotion rarely value technical reports. Partnership and collaboration with agencies is essential. Agency professionals have very specific environmental management objectives and priorities, often influenced by resource limitations. Academic scientists should adapt their research programs to accommodate agency research needs and priorities, and be willing to adopt research designs that best achieve agency objectives, even if those agencies are unable to financially support the effort. Often agencies can support research through in-kind match for field and laboratory work, or with research staff assistance. When partnerships are strong, “request for proposals” (RFPs) from state and local governmental agencies can be customized for specific talents found among academics.