Capture and Mortality Rates of Ducks in Selected Trap Types

ABSTRACT We evaluated different trap styles and related mortality of trapped ducks (Anas spp.) for 3 field seasons as part of the United States-Canada Cooperative Waterfowl Banding Program. During 2002, we evaluated 4 trap designs and caught 10,966 ducks. Trap style affected capture rates (P = 0.018, F₅ = 9.02), with Benning II and oval traps catching more ducks than cloverleaf and star traps. In 2003, we tested 3 trap styles and caught 10,849 ducks. Trap style affected duck capture rates (P < 0.01, F₅ = 15.16), with oval traps with 6-m lead panels catching more ducks than Benning II traps and cloverleaf traps. During 2004, we tested 3 trap styles and caught 11,737 ducks. Trap style affected capture rates (P < 0.01, F₅ = 11.23), with oval traps with 6-m leads catching more ducks than either the oval trap without leads or Benning II traps. Trap style affected mortality rates of ducks, but overall mortality of trapped ducks was low with a rate of 1.16% in 2002, 0.32% in 2003, and 0.17% in 2004; mortality was not a major problem in our study. Waterfowl managers may be able to catch more ducks using oval traps with leads without increasing mortality of captured ducks.     

Long Distance Transport of Abscisic Acid in NaCI-Treated Intact Plants of Lupinus albus

Plants of Lupinus albus were grown for 51 d under control (1.1mol m^–3 NaCl) and saline (40 mol m^–3 NaCl) conditions.Plants were harvested and changes of carbon, nitrogen and abscisicacid (ABA) contents of individual organs were determined 41d and 51 d after germination. In the period between the twoharvests xylem and phloem saps were collected and respirationand photosynthesis of individual organs were measured. Usingflows of carbon, C/ABA ratios and increments of ABA flows ofABA in phloem and xylem and rates of biosynthesis and degradationof ABA were calculated. Both under control and saline conditionsnet biosynthesis occurred in the root, the basal strata of leavesand in the inflorescence. Metabolic degradation of ABA tookplace in the stem internodes and apical leaf strata. Salt stress increased xylem transport of ABA up to 10-fold andphloem transport to the root up to 5-fold relative to that ofthe controls. A considerable amount of ABA in the xylem saporiginated from biosynthesis in the roots, i.e. 55% in salt-treatedand smaller than 28% in control plants. The remaining part ofABA in the xylem sap originated from the shoot: it was translocatedin the phloem from fully differentiated leaves towards the rootand from there it was recirculated back to the aerial partsof the plant. The data suggest that ABA may serve as a hormonalstress signal from the root system. Key words: Lupinus albus, salt stress, abscisic acid, long distance transport     

Concentrations and Transport of Solutes in Xylem and Phloem along the Leaf Axis of NaCl-treated Hordeum vulgare

Hordeum vulgare cv. California Mariout was established in sandculture at two different NaCl concentrations (0.5 mol m^–3‘control’ and 100 mol m^–3) in the presenceof 6.5 mol m^–3 K ⁺. Between 16 and 31 d after germination,before stem elongation started, xylem sap was collected by useof a pressure chamber. Collections were made at three differentsites on leaves 1 and 3: at the base of the sheath, at the baseof the blade, i.e. above the ligule, and at the tip of the blade.Phloem sap was collected from leaf 3 at similar sites throughaphid stylets. The concentrations of K ⁺, Na⁺, Mg2⁺ and Ca²⁺were measured. Ion concentrations in xylem sap collected at the base of leaves1 and 3 were identical, indicating there was no preferentialdelivery of specific ions to older leaves. All ion concentrationsin the xylem decreased from the base of the leaf towards thetip; these gradients were remarkably steep for young leaves,indicating high rates of ion uptake from the xylem. The gradientsdecreased with leaf age, but did not disappear completely. In phloem sap, concentrations of K⁺ and total osmolality declinedslightly from the tip to the base of leaves of both controland salt-treated plants. By contrast, Na⁺ concentrations inphloem sap collected from salt-treated plants decreased drasticallyfrom 21 mol m^–3 at the tip to 7.5 mol m^–3 at thebase. Data of K/Na ratios in xylem and phloem sap were used to constructan empirical model of Na⁺ and K⁺ flows within xylem and phloemduring the life cycle of a leaf, indicating recirculation ofNa⁺ within the leaf. Key words: Hordeum vulgare, xylem transport, phloem transport, NaCl-stress     

THERAPEUTIC STRATEGIES FOR THE INHIBITION OF INDUCIBLE NITRIC OXIDE SYNTHASE—POTENTIAL FOR A NOVEL CLASS OF ANTI-INFLAMMATORY AGENTS

In recent years, NO, a gas previously considered a potentially toxic chemical, has become established as a diffusible universal messenger mediating cell—cell communication throughout the body. In mammals, NO is a recognized mediator of blood vessel relaxation that helps to maintain blood pressure. In the central nervous system NO acts as a non-conventional neurotransmitter and participates in the establishment of long-term plasticity required for memory formation. In addition, NO is responsible for some parts of the host response to sepsis and inflammation and contributes to certain disease states. A number of strategies have emerged with regard to a pharmacological control of pathological NO overproductions. This review will discuss these novel therapeutic approaches that may provide new means for clinical medicine.     

Ionic Relations of Garden Orache, A triplex hortensis L.: Growth and Ion Distribution at Moderate Salinity and the Function of Bladder Hairs

The growth of garden orache, A triplex hortensis was studiedunder conditions of mild NaCl or Na₂SO₄ salinity. Growth, drymatter production and leaf size were substantially stimulatedat 10 mM and 50 mM Na⁺ salts. Increased growth, however, appearedto be due to a K⁺-sparing effect of Na⁺ rather than to salinityper se. The distribution of K⁺ and Na⁺ in the plant revealeda remarkable preference for K+ in the roots and the hypocotyl.In the shoot the K/Na ratio decreased strongly with leaf age.However, the inverse changes in K⁺ and Na⁺ content with leafage were dependent on the presence of bladder hairs, which removedalmost all of the Na⁺ from the young leaf lamina. Measurementsof net fluxes of K⁺ and Na⁺ into roots and shoots of growingAtriplex plants showed a higher K/Na selectivity of the netion flux to the root compared to the shoot. With increasingsalinity the selectivity ratio S_{K, Na}^* of net ion fluxes tothe roots and to the shoots was increased. The data suggestthat recirculation of K⁺ from leaves to roots is an importantlink in establishing the K/Na selectivity in A. hortensis plants.The importance of K⁺ recirculation and phloem transport forsalt tolerance is discussed. Key words: Atriplex hortensis, Salinity, Potassium, Sodium, K⁺ retranslocation, Bladder hairs, Growth stimulation     

Effect of Exogenous Glycinebetaine on Na+ Transport in Barley Roots

Ahmad, N., Wyn Jones, R. G. and Jeschke, W. D. 1987. Effectof exogenous glycinebetaine on Na⁺ transport in barley roots.—J.exp. Bot. 38: 913–921. A comparison has been made of the kinetics of 22Na⁺ uptake intoexcised barley roots and roots pre-loaded with glycinebetaine.The elevated intracellular glycinebetaine or a metabolic consequencethereof increased the Na⁺ influx, and the effect was relatedto the level of internal glycinebetaine and or Na⁺ [Cl^–].The quasi-steady-state Na⁺ influx at the tonoplast rather thanthe plasmalemma influx was apparently influenced by glycinebetaineloading. The tonoplast fluxes and vacuolar Na⁺ content wereconsistently higher in glycinebetaine-loaded roots than unloadedroots. A membrane-modifying role of glycinebetaine in relationto ion compartmentation is discussed. Key words: Excised roots, glycinebetaine, Na⁺, ion fluxes, barley     

Strategies of passerine migration across the Mediterranean Sea and the Sahara Desert: a radar study

Radar observations of the diurnal timing of bird migration in the Sahara Desert are presented for autumn migration. Study sites were on a transect along the north-south migratory direction. Three groups of birds migrating either during day, evening or night in the northern part of the Western desert in Egypt were identified. The maximum of day and night groups occurred later the further south the study sites were. Based on the distance between sites and the timing of peak migration, birds were flying at an estimated ground speed of about 20 m/s. The maximum of the evening group was at about 21:00 h at all sites. The three groups were classified according to three different strategies of migration across the Mediterranean Sea and the Sahara Desert: (1) the day group of birds performed a non-stop flight across the sea and at least the northern part of the desert; [2] the night group performed an intermittent migratory strategy with stopover at the coast of Egypt to continue migration the next evening; (3) the evening group birds were also intermittent migratory fliers, but they stopped somewhere in the desert after a continuous flight across the sea and part of the desert. About 20% of all migrants are involved in non-stop migration and 80% in intermittent migration with stopover at the coast (70%) or with stopover in the desert (10%). It is argued that any species of small passerine has the option to use any of the three strategies.     

A matter of timing: heat wave impact on crustacean zooplankton

1. Climate change has affected zooplankton phenology and abundance in many freshwater ecosystems. The strong temperature anomalies that characterise summer heat waves make these events particularly suitable to study the effects of different seasonal warming patterns on zooplankton. Since heat waves are expected to occur more frequently under continuing climate change, they may also allow us to investigate how freshwater systems will be affected in the future. 2. Using a long‐term data set (1991–2007) from a shallow, eutrophic lake in Germany, we identify time periods in spring and summer during which cyclopoid copepods and bosminids are particularly sensitive to changes in water temperature. Based on this knowledge, we consider why summer populations responded differently to recent heat wave events that occurred at different times in the season. 3. Linear regressions of moving averages suggested that water temperatures shortly before and shortly after the clear‐water phase (CWP) were crucial for summer development of bosminids and cyclopoid copepods, respectively. Algal food availability (diatoms and cryptophytes) in the first weeks after the CWP also strongly influenced the summer populations of the two zooplankton groups. 4. Inter‐annual differences in water temperature during the critical time periods at least partly explained the contrasting responses of cyclopoid copepods and bosminids to heat wave events. 5. Our findings indicate that the zooplankton response to climate warming, particularly to heat wave events, is critically dependent on the temporal pattern of elevated water temperatures. Beyond that, we show that the summer zooplankton populations react to periods of warming in relation to events in the plankton annual cycle (such as the CWP in eutrophic lakes) rather than to warming at a fixed time in the season.