The objective of the work proposed here is to obtain direct measurements of bottom stress in the nearshore environment, where water depths are on the order of meters, energetic currents are forced by both winds and waves, and flows of water and sand are of primary scientific interest and practical concern. Bottom stress (the drag exerted on the sea floor by an oceanic flow) is particularly important in the nearshore environment, where it is believed to play a dominant role in controlling the motion of both water and sand. Bottom stress has not previously been measured in this environment because of fundamental problems produced by surface waves. The proposed measurements will capitalize on a new technique, developed at WHOI within the past year, which has been shown in pilot studies to overcome these problems. The measurements will permit a test of the basic force balance that has traditionally been assumed to hold in the nearshore environment, and they will elucidate the mechanisms by which drag is transmitted to the sea floor.

The proposed measurements will be part of an intensive, multi-investigator field program named Sandyduck, which will occur in Duck, North Carolina during summer and fall of 1997. This program provides an excellent opportunity because other Sandyduck investigators will obtain the high-quality measurements of winds and waves that are essential in order to place the proposed measurements of bottom stress in context. The funding requested here will be applied to purchase and development of the instrumentation required to measure bottom stress. Additional funding for other equipment purchases, participation in the experiment and analysis will be drawn from other sources.

We propose to initiate a research program to detect and isolate genes expressed by a variety of symbiosis-forming algae. We have successfully isolated and cultured a variety of symbiotic algae from several planktonic protozoan species. We propose to use these algae to establish an inducible symbiotic system using the marine ameba Trichosphaerium. We will use state-of-the-art molecular biological approaches to determine which genes are involved in establishing and maintaining the symbiotic relationship. The basis for our program is the hypothesis that photosymbioses result from the induction and expression of specific genes that are held in common among disparate symbiosis-forming algae. Therefore, comparison of the genes expressed from a broad range of symbiotic algae in hospice can be used as a tool to identify those genes expressed specifically for the purpose of establishing and maintaining the symbiotic relationship.

No underwater sonar device currently available performs as well as the bottlenosed dolphin. This project will improve our understanding of the mechanisms behind dolphin sonar by producing computerized models of the outer and middle ear components that are essential to the dolphin's sonar signal transduction and analysis abilities. Computerized tomography of dolphin heads implanted with micro-hydrophores will be used to locate tissue paths specific for water-borne sound, to measure sonic velocities in these paths, and to analyze how received signals are altered compared to the incident sound at each stage of the auditory path. Finite element models will be developed that simulate responses of dolphin ears to a range of acoustic stimuli. These models will provide insights into how each ear component relates to hearing underwater sound and ultrasonics. They will also provide data necessary for the development of a comprehensive, computerized marine mammal hearing model that will allow us to estimate hearing sensitivities for rare and untestable species, such as the sperm whale and blue whale, and to explore possible effects of noise on marine mammal ears.

Permeability describes the ease with which fluid can move through the void space in porous or fractured rock. Although it is understood that permeability displays scale-dependent behavior, the measurements necessary to characterize such behavior over distances larger than ~0.1 m are exceedingly difficult to make. Electrical conductivity, like permeability, is a transport property with wide variability whose magnitude depends on the length scale over which measurements are made. Unlike permeability, electrical conductivity can be measured simply and noninvasively over a wide range of length scales. The electrical conductivity of sandstone is primarily controlled by pore fluid geometry, but while electrical conductivity is commonly used to diagnose the presence of groundwater, the conversion from conductivity to permeability remains problematic.

This proposal seeks funding for one component of a larger study, the aim of which is to characterize the electrical conductivity of the eolian Page sandstone (located near the Utah/Arizona border) over length scales from 1 cm-200 m. The total effort entails an integration of laboratory studies and multi-scale electromagnetic surveys, with the aim of developing methodologies through which electrical conductivity measurements may be used as a reliable proxy for permeability. Here, we seek to establish the first essential link between laboratory and field measurements, through measurements of the small-scale (1 cm-1 m) behavior of electrical conductivity, and by so doing pave the way for the larger and more comprehensive study of scale dependence of transport properties.

I have developed a new model for the volcanic construction of oceanic crust at mid-ocean ridges (MOR) that successfully explains the spectacular seismic images of the shallow oceanic crustal structure along the East Pacific Rise and provides a new context for the interpretation of results of DSDP/ODP drilling in ocean crust. This bimodal lava deposition model predicts as a function of a few parameters the variation in shallow crustal structure across a seafloor spreading center, the abundance of dikes in the lava sequence of the upper ocean crust, and the post-depositional rotation of the lavas as they are buried by younger lava flows. The model is based on a relation between field geology and the CCSP CY-1/lA drill cores in the Troodos ophiolite on Cyprus (ophiolites-portions of ancient oceanic lithospere emplaced onto continental margins during erogenic events-are accessible, oceanic crustal analogues for studying the geology of ocean crust in the field).

I propose to conduct a two-week field study in Cyprus to perform a quantitative comparison between surface geology and drill holes in the Troodos ophiolite, which is the only ophiolite that has been drilled. This comparison will represent a proof of concept, a critical test of the model and the proposed relation between drill holes and geology, which should serve to convince the NSF and colleagues working in the Troodos ophiolite that a systematic study of the relation between Troodos field geology and the Cyprus drill cores will be appropriate and profitable. In a broader context, a further substantiation of the proposed relation (i.e., how accurately do the local Cyprus drill cores describe the regional geology of the ophiolite?) will provide an essential framework for the geologic interpretation of the DSDP/ODP drill holes in ocean crust, which are our primary tools for sampling ocean crust to study its evolution (field mapping of the ocean crust, the way ophiolites are mapped, would require deployment of submersibles, deeply towed, remotely operated and other underwater vehicles too costly to be realistic). In the well-defined context of the bimodal lava deposition model, the proposed field study of selected areas in the Troodos ophiolite and of its cores aims to forge a definitive link between ophiolites and ocean crust through their drill cores, which will contribute greatly toward further understanding of the evolution of ocean crust.

Marine sediments contain a large amount of calcium carbonate, mostly as the mineral, calcite. Reaction of CO₂ in deep waters with this calcium carbonate is believed to be an important part of the mechanism that controls atmospheric CO₂ concentrations on intermediate and long time scales (hundreds to thousands of years). Thus, quantifying the rate of dissolution of sedimentary calcium carbonate is important to the development of predictive and interpretive models of the carbon cycle. Unfortunately, the existing measurements, upon which the kinetic description of calcite dissolution is based, contain uncertainties that greatly restrict our ability to quantify the reaction rate. Recent advances in procedures for pH measurement in seawater have led to improvements of on the order of a factor of 10 in accuracy and precision. I propose to use these new techniques to develop a system for the determination of calcite dissolution rate and saturation product. The work carried out under this grant would serve as the basis for an effort at combining this experimental work with field programs in the tropical Atlantic and Pacific oceans, allowing us to re-evaluate the rate law for calcite dissolution and to evaluate possible spatial variability in the effective saturation product for calcite and its rate of dissolution.

Organic matter cycling in marine systems occurs on many different time scales. Biological uptake and cycling of simple dissolved substances (glucose, amino acids) occurs in only a few hours, while the generation of petroleum and gas in deep sedimentary basins requires several million years. Different techniques and approaches have been employed to study cycling over such diverse time scales; radiotracer and incubation experiments are used to study cycling over 1-100 hr timescales, while radiocarbon and stable isotope measurements are used to study cycling on 10²-10⁶ yr timescales. There is an important gap in our ability to quantify cycles with intermediate time scales of 1-10 years. Annual and decadal cycles are too long for incubation and laboratory tracer experiments, and are difficult to monitor directly by time series measurements. Yet it is on these timescales that much of the organic carbon present in seawater and surface sediments is reprocessed. Here we propose to develop an approach which takes advantage of the incorporation of sea water tritium (half life = 12.45 yrs) into organic matter to quantify DOC cycling in the upper and mid water column. If successful, our research will both address an important issue in the upper ocean carbon cycle and introduce a new approach which has many interesting potential applications for studying carbon cycling in seawater and recent sediments.

I would like support to write a book on "rotating hydraulics" this summer and fall in conduction with Larry Pratt. The area of study involves fluid flows that are constricted to the point where the upstream conditions must be altered. In this way, small localities have influence over large regions. All progress in this subject, which we hope to describe in the book, was made in about the last decade. This will be the topic of the upcoming Geophysical Fluid Dynamics Summer Study Program. Dr. Pratt will be the principal lecturer, I will be the director, and most experts in this area will attend. We both have worked on this area for about twenty years, so this is a perfect time to produce such a study. Assorted examples are known in the ocean. Support will aid the bulk of the work on the text including the production of figures.

The evidence that mantle anisotropy is due to the strain-induced, lattice preferred orientation of upper mantle minerals has provided a means of inferring the mode of mantle deformation from observations of seismic anisotropy. In the presence of multiple layers of seismic anisotropy or complex flow, however, the interpretation of seismic anisotropy is difficult due to the lack of depth resolution in previous studies. The proposed study will explore a new method to obtain better depth, azimuthal and lateral resolutions of seismic anisotropy than in previous studies. Existing, broadband earthquake records from the global seismic networks and arrays (including oceanic island stations) will be used.

All organisms disperse at some stage in their life history, and many organisms have evolved elaborate anatomical and behavioral mechanisms for dispersal. Yet little is known about the evolutionary advantages of dispersal. What we do know comes from the analysis of a few simple mathematical models. Unfortunately, these models are built upon a number of unrealistic biological assumptions. Principal among these is the assumption that dispersal is diffusive. In fact, the dispersal curves of most organisms are characterized by longer dispersal distances than a diffusion model would allow. I am proposing to study the evolution of dispersal using a new modelling framework that would allow me to incorporate more realistic dispersal mechanisms.