Chuck Fisher* and the RIDGE 2000 Steering Committee. Ridge 2000 Office, Department of Biology, Penn State University, 208 Mueller Lab Univerity Park, PA 16802, USA; e-mail ridge2000@psu.edu

Chuck Fisher* and the RIDGE 2000 Steering Committee. Ridge 2000 Office, Department of Biology, Penn State University, 208 Mueller Lab Univerity Park, PA 16802, USA; e-mail ridge2000@psu.edu.

Over the last 50 years, systematic observation and sampling of the world’s oceans have led to significant discoveries. This basic oceanographic research provided crucial evidence for the landmark theories of seafloor spreading and plate tectonics, and led to the discovery of ecosystems based on chemoautotrophy rather than photosynthesis. The RIDGE 2000 Program was conceived to promote an integrated approach towards the study of mid-ocean ridges. Outlined by community workshops over the past two years, it builds directly on the scientific and technological successes of the RIDGE Program. The scientific motivation for the RIDGE 2000 Program is encapsulated in the phrase “from mantle to microbes…” that expresses the inextricable linkages between processes of planetary renewal in the deep ocean and the origin, evolution and sustenance of life in the absence of sunlight.

The RIDGE 2000 Science Plan aims for a comprehensive understanding of the relationships between the geological processes of plate spreading at mid-ocean ridges and the seafloor and sub-surface ecosystems that they support. Research under this program will be structured within an integrated, whole-system approach that will encompass a wide range of disciplines. Detailed studies of specific geographic areas will yield new insights into the connections among the biological, chemical and geological processes that are involved in crustal accretion and subsequent ridge crest processes.


Mussel mimics: an innovative way to show some intertidal mussels just aren't cool

Tara Fitzhenry,* Brian Helmuth, Kristi Gardner. University of South Carolina, Marine Science Program, Columbia SC, 29208, USA.

Intertidal mussels (Mytilus californianus) live between the high and low tide lines of rocky coastlines of the northeastern Pacific, and are cyclically subjected to both aquatic and terrestrial environments. This alternating exposure can lead to rapid and sometimes extreme changes in body temperature, which in turn can have significant and even deadly physiological consequences. Because small temperature loggers have recently become available there are few long-term records of body temperature recorded under field conditions (Helmuth and Hofmann 2001). In order to estimate temperatures in the field we deployed a series of temperature loggers that were designed to thermally match live mussels (similar size, morphology and thermal inertia) at two sites in central Oregon (Boiler Bay and Strawberry Hill). Previous studies have shown that ecological and physiological patterns differ between these two sites, and may be a result of temperature effects, but this hypothesis has yet to be addressed. In controlled experiments, Mytilus californianus did not appear to gape to evaporately cool and therefore evaporation rates were not taken into account. Tests comparing these loggers to real mussels suggest that thermally-matched loggers recorded temperatures that are within a few degrees of real animals, and are considerably more accurate than unmodified loggers. Mussel logger temperatures at these sites reached maxima of 35° or greater, close to the predicted thermal tolerance of this species.To date, results indicate that temperature extremes at the Oregon site are quite high, and are comparable to temperatures recorded much farther south in California. Results suggest that temperature extremes might be slightly higher at the Strawberry Hill site than at Boiler Bay, in accordance with the pattern hypothesized by Dahlhoff and Menge (1996).


Life history observations of newly settled corals (Montastraea annularis species complex) over the first half-year post-settlement

Nicole Fogarty* and Alina M. Szmant. Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Ln, Wilmington NC 28409, USA.

Few studies have documented survivorship patterns of newly settled corals and their interactions with surrounding organisms that are critical to recruitment success. Larvae of the Caribbean coral, Montastraea annularis, were settled in the laboratory on coral rubble or pre-conditioned clay and quarried limestone tiles. Observations began within a few days after settlement, but most were made beginning seven weeks later. Substrates were maintained either in running recirculating seawater (high light) or in shallow trays (low light) with water replaced weekly. Polyps were mapped, the substrate around them characterized, and spat observed. Of the 600+ initial polyps, 32% were on the 12 pieces of rubble, 26% on the 2 clay tiles , and 43% on the 2 limestone tiles. Settlement density was highest on the bottom surfaces of the limestone (8600/m²), and lowest on the tops and bottoms of the clay tiles (ca. 1700/m²). 73% of the larvae settled in aggregates of 2 to 3. More larvae settled on tile bottoms than tops (57 to 68 %). 41% settled < 1 cm from crustose coralline algae (CCA), 15% on CCA and 44% > 1cm from CCA patches. Zooxanthellae infection began one week after settlement; some polyps took 2 weeks to acquire them. Theca secretion was completed within 2 weeks. Skeletal and tissue fusion of aggregated polyps began 8-10 weeks post-settlement, with the exception of 1 cluster of 5, which fused within 1 month of settlement and began to produce extratentacular buds after 14 weeks. High mortality of spat in the well-lit seawater system was caused by algal overgrowth. Juvenile Diadema reduced algal overgrowth but sometimes ate the coral spat as well. Survivorship was greatest in the trays where at low light levels algal growth was considerably less. Overall survivorship after 5.5 months was 25%.