The contribution of fog to the water relations of Sequoia sempervirens (D. Don): foliar uptake and prevention of dehydration

Fog is a defining feature of the coastal California redwood forest and fog inputs via canopy drip in summer can constitute 30% or more of the total water input each year. A great deal of occult precipitation (fog and light rain) is retained in redwood canopies, which have some of the largest leaf area indices known (Westman & Whittaker, Journal of Ecology 63, 493–520, 1975). An investigation was carried out to determine whether some fraction of intercepted fog water might be directly absorbed through leaf surfaces and if so, the importance of this to the water relations physiology of coast redwood, Sequoia sempervirens. An array of complimentary techniques were adopted to demonstrate that fog is absorbed directly by S. sempervirens foliage. Xylem sap transport reversed direction during heavy fog, with instantaneous flow rates in the direction of the soil peaking at approximately 5–7% of maximum transpiration rate. Isotopic analyses showed that up to 6% of a leaf's water content could be traced to a previous night's fog deposition, but this amount varied considerably depending on the age and water status of the leaves. Old leaves, which appear most able to absorb fog water were able to absorb distilled water when fully submersed at an average rate of 0.90 mmol m² s^?1, or about 80% of transpiration rates measured at the leaf level in the field. Sequoia sempervirens has poor stomatal control in response to a drying atmosphere, with rates of water loss on very dry nights up to 40% of midday summer values and rates above 10% being extremely common. Owing to this profligate water use behaviour of S. sempervirens, it appears that fog has a greater role in suppressing water loss from leaves, and thereby ameliorating daily water stress, than in providing supplemental water to foliar tissues per se. Although direct foliar absorption from fog inputs represents only a small fraction of the water used each day, fog's in reducing transpiration and rehydrating leaf tissues during the most active growth periods in summer may allow for greater seasonal carbon fixation and thus contribute to the very fast growth rates and great size of this species.     

Eimeria ornata N. Sp. (Apicomplexa: Eimeriidae) from the Ornate Box Turtle, Terrapene ornata ornata (Reptilia: Testudines), in Texas

Eimeria ornata n. sp. is described from the feces of 6/16 (37.5%) ornate box turtles, Terrapene ornata ornata , in northcentral Texas. Endogenously sporulated oocysts are ellipsoid 17.9 × 15.7(16-21 × 14-18) μm, with a thin, single-layered wall; shape index 1.14 (1.0-1.3). A micropyle is absent but a polar granule was present in one third of the oocysts. An oocyst residuum was present, consisting of numerous small globules situated either in a distinct mass or scattered within the oocyst. The sporocysts are elongate, 11.1 × 5.4 (9-13 × 5-6) μm, with an indistinct Stieda body at 1 pole. A sporocyst residuum is present, consisting either as a compact mass or as scattered granules. The sporozoites are elongate, 9.5 × 2.0 (8-12 × 2) μm, in situ, with spherical anterior and posterior refractile bodies. The new species is distinguished from the similar Eimeria carri Ernst & Forrester, 1973, from eastern box turtles, T. Carolina , by slight differences in oocyst morphology and endogenous sporulation.     

Identification of Sporozoite Surface Proteins and Antigens of Eimeria nieschulzi (Apicomplexa)

Sodium dodecyl sulfate polyacrylamide gel electrophoresis, immunoblotting, lectin binding, and ¹²⁵I surface labeling of sporozoites were used to probe sporozoites of the rat coccidian, Eimeria nieschulzi. Analysis of silver stained gels revealed >50 bands. Surface iodination revealed about 14 well labeled, and about 10 weakly labeled but potential, surface proteins. The most heavily labeled surface proteins had molecular masses of 60, 53–54, 45, 28, 23–24, 17, 15, 14, 13, and 12 kD. Following electrophoresis and Western blotting, 2 of the 12 ¹²⁵I labeled lectin probes bound to two bands on the blots, which collectively indicated that two bands were glycosylated. Concanavalin A (ConA) specifically recognized a band at 53 kD, which may represent a surface glycoprotein, and a lectin derived from Osage orange (MPA) bound to a single band at 82–88 kD, that may also be a surface molecule. Immunoblotting using sera collected from rats inoculated orally with oocysts, as well as sera from mice hyperimmunized with sporozoites, revealed that many surface molecules appear to be immunogenic.     

Pyrethroid resistance in Australian field populations of the sheep body louse, Bovicola (Damalinia) ovis

Abstract. Synthetic pyrethroid (SP) resistance has developed in Australian field populations of the sheep body louse, Bovicola ( Damalinia ) ovis. Laboratory bioassays were used to measure the susceptibility of lice to cypermethrin and the other registered SPs. Results of these bioassays indicated resistance to cypermethrin, deltamethrin, cyhalothrin and alphacypermethrin. So far, high-level resistance has been diagnosed in only a few strains. The toxicological responses of these strains were clearly separated from those of the majority of louse strains tested. Furthermore, these strains had survived immersion in commercial SP dips. The level of resistance described in some strains was sufficient to cause pour-on products to fail despite the fact that the LC50s of these strains fell within the normal range of field responses.     

Characterization of 20 microsatellite loci in the long‐tailed tit Aegithalos caudatus (Aegithalidae,AVES)

We characterized 20 microsatellite loci in the long‐tailed tit, Aegithalos caudatus. Polymorphic loci were identified by testing 114 loci that had been originally isolated in other avian species. The loci were characterized in 23–163 unrelated long‐tailed tits from a British population and displayed between two and 42 alleles, with observed heterozygosity ranging between 0.09 and 0.97.     

The timing of gonadal development and moult in three raptors with different breeding seasons: effects of gender, age and body condition

Differences between species in breeding seasons are thought to be mediated through differences in their reproductive physiology. Little is known about how the timing and duration of gonadal maturation varies between raptor species, how the timing of moult relates to the gonadal cycle, whether the timing and degree of sexual maturation varies between juveniles and adults or whether body condition has a significant effect. To address these questions, data on gonadal size and moult for adults and juveniles of both sexes of three raptor species were extracted from the Predatory Bird Monitoring Scheme (based on birds found dead by members of the public). The three species, Sparrowhawk Accipiter nisus, Kestrel Falco tinnunculus and Barn Owl Tyto alba, have different ecologies – diurnal bird predator, diurnal mammal predator and nocturnal mammal predator, respectively. All are single‐brooded but have different breeding seasons. The duration of gonadal maturation was markedly different between the species. Barn Owls showed the earliest maturation and the latest gonad regression, and Sparrowhawks the latest maturation and earliest gonad regression. Kestrels were intermediate. In males of all species, the testes remained fully mature throughout their respective breeding seasons. In females, the ovaries remained partially mature throughout the breeding season. Moult started slightly earlier in Sparrowhawks than in Kestrels and coincided with gonadal regression in the two species. Although females of the two species started to moult earlier than males, moult duration was similar between the sexes. Barn Owls showed no distinct annual pattern of moult. In juveniles of all three species, the gonads were smaller than in adults throughout spring and started to mature later. Gonad size in birds that had starved tended to be smaller than in birds dying from other causes, but did not influence the difference in gonad mass between adults and juveniles and between seasons. Body condition had no effect on moult. Whilst ecology has led to the evolution of different breeding seasons, differences between species, and between adults and juveniles, are mediated through adaptive differences in their reproductive physiology.     

Fog interception by Sequoia sempervirens (D. Don) crowns decouples physiology from soil water deficit

Although crown wetting events can increase plant water status, leaf wetting is thought to negatively affect plant carbon balance by depressing photosynthesis and growth. We investigated the influence of crown fog interception on the water and carbon relations of juvenile and mature Sequoia sempervirens trees. Field observations of mature trees indicated that fog interception increased leaf water potential above that of leaves sheltered from fog. Furthermore, observed increases in leaf water potential exceeded the maximum water potential predicted if soil water was the only available water source. Because field observations were limited to two mature trees, we conducted a greenhouse experiment to investigate how fog interception influences plant water status and photosynthesis. Pre-dawn and midday branchlet water potential, leaf gas exchange and chlorophyll fluorescence were measured on S. sempervirens saplings exposed to increasing soil water deficit, with and without overnight canopy fog interception. Sapling fog interception increased leaf water potential and photosynthesis above the control and soil water deficit treatments despite similar dark-acclimated leaf chlorophyll fluorescence. The field observations and greenhouse experiment show that fog interception represents an overlooked flux into the soil–plant–atmosphere continuum that temporarily, but significantly, decouples leaf-level water and carbon relations from soil water availability.