Alkaloids of the leaves of Erythrophleum chlorostachys

From the leaves of Erythrophleum chlorostachys (F. Muell.) Bail. growing at Mareeba, North Queensland, β-dimethylaminoethyl cinnamate (II), N-2-hydroxyethyl-N-methyl cinnamamide (III), N-2-hydroxyethyl-N-methyl-trans-p-hydroxycinnamamide (IV) and N-2-hydroxyethylcinnamamide (V) were isolated. The structures were confirmed by synthesis. The amides (III), (IV) and (V) may possibly be artefacts of isolation since, as free bases, the cinnamic esters isomeric with (III) and (V) rearrange to (III) and (V) respectively, with half-lives less than 3 days and 1 day, respectively. Leaves of E. chlorostachys growing at Cooktown, North Queensland, and at Darwin, N.T., did not contain these compounds but contained alkaloidal esters of diterpenoid acids as in other Erythrophleum species

Coherent assembly of phytoplankton communities in diverse temperate ocean ecosystems

The annual cycle of phytoplankton cell abundance is coherent across diverse ecosystems in the temperate North Atlantic Ocean. In Bedford Basin, on the Scotian Shelf and in the Labrador Sea, the numerical abundance of phytoplankton is low in spring and high in autumn, thus in phase with the temperature cycle. Temperature aligns abundance on a common basis, effectively adjusting apparent cell discrepancies in waters that are colder or warmer than the regional norm. As an example of holistic simplicity arising from underlying complexity, the variance in a community variable (total abundance) is explained by a single predictor (temperature) to the extent of 75% in the marginal seas. In the estuarine basin, weekly averages of phytoplankton and temperature computed from a 13 year time-series yield a predictive relationship with 91% explained variance. Temperature-directed assembly of individual phytoplankton cells to form communities is statistically robust, consistent with observed biomass changes, amenable to theoretical analysis, and a sentinel for long-term change. Since cell abundance is a community property in the same units for all marine microbes at any trophic level and at any phylogenetic position, it promises to integrate biological oceanography into general ecology and evolution

Rethinking the Use of Seabed Sediment Temperature Profiles to Trace Submarine Groundwater Flow

Submarine groundwater fluxes across the seafloor facilitate important hydrological and biogeochemical exchanges between oceans and seabed sediment, yet few studies have investigated spatially distributed groundwater fluxes in deep-ocean environments such as continental slopes. Heat has been previously applied as a submarine groundwater tracer using an analytical solution to a heat flow equation assuming steady state conditions and homogeneous thermal conductivity. These assumptions are often violated in shallow seabeds due to ocean bottom temperature changes or sediment property variations. Here heat tracing analysis techniques recently developed for terrestrial settings are applied in concert to examine the influences of groundwater flow, ocean temperature changes, and seabed thermal conductivity variations on deep-ocean sediment temperature profiles. Temperature observations from the sediment and bottom ocean water on the Scotian Slope off eastern Canada are used to demonstrate how simple thermal methods for tracing groundwater can be employed if more comprehensive techniques indicate that the simplifying assumptions are valid. The spatial distribution of the inferred groundwater fluxes on the slope suggests a downward groundwater flow system with recharge occurring over the upper-middle slope and discharge on the lower slope. We speculate that the downward groundwater flow inferred on the Scotian Slope is due to density-driven processes arising from underlying salt domes, in contrast with upward slope systems driven by geothermal convection. Improvements in the design of future submarine hydrogeological studies are proposed for thermal data collection and groundwater flow analysis, including new equations that quantify the minimum detectable flux magnitude for a given sensor accuracy and profile length.</p