A 22 m sediment core was collected from the unsaturated zone (USZ) in the dunes south of Ashdod, Israel, in a low rainfall year, following an even lower-rainfall year. The mineralogy of was quartz with some clay and carbonate. The local climate is semi-arid. The roots of the sparse vegetation can reach ~8 m. The porosity was ~40–55%. The DIC ranged from 2 to 13 mmole C/L. Large variability is noted in the soil moisture, with a maximum at the high clay region at ~8 m. Oxygen isotopes enter the USZ with rain falling on the surface. There is 18O enrichment in the top of the section due to evaporation during the summer. Below this depth δ18O values of ~ –5‰ prevail as in the local aquifer. CO2 and the carbon isotopes enter the USZ laterally by exhalation from roots. The δ13C varies from –5‰ to –23‰, representing stages in carbon isotopic fractionation: CO2gas becomes dissolved CO2aqueous which then forms carbonic acid and HCO3– . The high δ13C, Δ14C, and DIC are found at the 8 m depth. These values along with high humidity are replicated at ~22m depth. They most probably represent recharge water from the previous rainy season at 8 m depth subsequently pushed down 12.8±0.8 m during the last winter.

Water flow in plant tissues takes place in two different physical domains separated bysemipermeable membranes: cell insides and cell walls. The assembly of all cell insides andcell walls are termed symplast and apoplast,respectively. Water transport is pressure driven in both, where osmosis plays an essentialrole in membrane crossing. In this paper, a microscopic model of water flow and transportof an osmotically active solute in a plant tissue is considered. The model is posed on thescale of a single cell and the tissue is assumed to be composed of periodicallydistributed cells. The flow in the symplast can be regarded as a viscous Stokes flow,while Darcy’s law applies in the porous apoplast. Transmission conditions at the interface(semipermeable membrane) are obtained by balancing the mass fluxes through the interfaceand by describing the protein mediated transport as a surface reaction. Applyinghomogenization techniques, macroscopic equations for water and solute transport in a planttissue are derived. The macroscopic problem is given by a Darcy law with a force termproportional to the difference in concentrations of the osmotically active solute in thesymplast and apoplast; i.e. the flow is also driven by the local concentration differenceand its direction can be different than the one prescribed by the pressure gradient.

Improved coral cultivation will facilitate the reduction of wild harvesting, reef restoration, preservation of biodiversity, and the use of corals as model experimental organisms. In this study, we examine species-specific responses in growth and survival of corals from the effects of light, water motion and artificial (i.e. non-living aquarium trade) food supplements. Three species representing distinct, diverse and abundant coral genera were chosen (Montipora capitata(Mc), Porites compressa (Pc) and Pocillopora damicornis (Pd)) for three experiments to examine: (1) the interaction of water flow and light on growth and survival of Mc and Pc; (2) the effects of artificial foods on Mc, Pc and Pd; and (3) the effects of increasing dosage of artificial foods in an open system on Mc and Pc. Pc thrived at the highest light levels with low flow, while Mc exhibited bleaching and reduced growth in the same conditions and grew best in shaded treatments. High constant flow (~11 cm s-1) resulted in slightly less overall growth than low constant flow (~4 cm s-1). Some artificial foods resulted in a significant increase in growth in Mc and Pd, but not in Pc. These combined results suggest that Mc may be more heterotrophic than Pc. This study illustrates that each species has unique requirements for optimal growth conditions that can be determined by relatively simple and low cost experiments, but that ideal conditions for one species might not be generalized to others.

Myxobolus cerebralis, the myxozoan parasite responsible for whirling disease in salmonid fishes, has a complex life-cycle involving an invertebrate host and 2 spore stages. Water flow rate is an environmental variable thought to affect the establishment and propagation of M. cerebralis; however, experimental data that separates flow effects from those of other variables are scarce. To compare how this parameter affected parasite infection dynamics and the invertebrate and vertebrate hosts, dead, infected fish were introduced into a naïve habitat with susceptible hosts under 2 experimental flow regimes: slow (0·02 cm/s) and fast (2·0 cm/s). Throughout the 1-year study, uninfected fry were held in both systems, the outflows were screened weekly for spores and the annelid populations were monitored. We found clear differences in prevalence of infection in the worms, prevalence and severity of infection in the fish, and host survival. Both flows provided environments in which M. cerebralis could complete its life-cycle; however, both the parasite and its invertebrate host proliferated to a greater extent in the slow flow environment over the 1-year study period. This finding is of significance for aquatic systems where the flow rate can be manipulated, and should be incorporated into risk analysis assessments.