Flow-related patterns in abundance and composition of the fish fauna of a degraded Australian lowland river

1. A 7‐year study was conducted in three hydrologically distinct sections within the highly regulated, lowland Campaspe River to investigate the influence of hydrology on temporal and spatial patterns in fish composition, abundance and recruitment. One section had 6 months, one section 2 months and one section no months of increased flow due to storage releases. The fish fauna of the less regulated, nearby Broken River served as a reference to which that of the Campaspe River was compared for the last 3 years of the study to allow insight into the relative effects of hydrology, barriers to movement and other environmental characteristics. The study included one high‐flow year, a moderate‐flow year and five low‐flow years. 2. A total of 16 fish species – 10 native and six alien – were caught in the Campaspe River, although of the native species, only three are considered to have self‐sustaining populations. The remaining species are either itinerants or a result of stocking. Alien species comprised approximately 64% of the total biomass of all fish caught. 3. Overall composition of the fish fauna did not differ significantly by year, but did by section of river. Species richness and the abundance of most of the dominant species also differed significantly by river section, but there was little inter‐annual variation in the abundance of any species, except for European perch and for common carp; the latter showing an increase in abundance following a high‐flow event during the spring of 2000 as a result of recruitment. 4. Overall faunal composition was not influenced by hydrology. However, multiple regression indicated that species richness, abundance of the dominant species and abundance of young‐of‐year (YOY) of golden perch, European perch and common carp all were influenced significantly by hydrological variables. The nature of the relationships was dependent on river section and hydrological season (‘winter’ or ‘spring/summer’). Of note was the result that the total abundance of fish and that of YOY common carp were significantly positively related to the number of spells above the threshold for movement upstream through the lower two weirs in the Campaspe River. Only one significant relationship between hydrological and fish‐related variables was found for the upper river section, whereas seven and five were found for the lower and middle sections respectively. 5. Comparisons with fish collected in the Broken River over 3 years suggest that the fauna of the Broken River is in a more natural state than that of the Campaspe River. Since the two rivers do not differ substantially in water quality, and since both contain significant weirs, which act as barriers to movement of fish, flow regulation is most likely to be the major reason for the poor state of the fauna in the Campaspe River.     

Effect of seedling treatment on growth and yield of sugar beet in the field

Sugar-beet seeds were germinated (1) in a growth cabinet at 20°C lit continuously by fluorescent tubes (L), (2) in a cabinet at 20°C lit by fluorescent tubes for 16 h/day (S), (3) in a cage with glass roof and open sides with natural illumination (N), or (4) in the open ground (D). The seedlings from the cabinets and cage were transplanted to the field when they had two true leaves. Samples were taken on six occasions during growth, and leaf areas and dry weights determined. There were no differences between treatments in total number of leaves produced or leaf area duration. Leaf area per plant increased fastest on L plants at first, but from mid-June until end of July drilled plants had the largest leaf surface. From August onwards S plants had the largest area. Although treatment had little effect on growth of the tops, roots grew fastest throughout the season on the plants raised in growth cabinets and the final mean root dry weight of L and S plants was 39% greater than of N and D plants. Throughout the season L and S plants had a larger root:top ratio than plants raised in the cage or drilled directly in the field. The larger roots of plants raised in the cabinets evidently provided a larger sink for carbohydrate and increased the mean photosynthetic efficiency of the leaves over the whole season by 11 % and increased yield of roots by 6 tons/acre.     

THE USE OF SEED DRESSINGS CONTAINING γ-BHC IN THE ESTABLISHMENT OF SUGAR-BEET SEEDLINGS

From 1949 to 1952 field trials were made to determine the effect of seed dressings containing γ-BHC, with and without the addition of organic mercurial compounds, upon the establishment of sugar-beet seedlings. Most of the trials were made in fields where no serious pest problems were anticipated. The 1949 trials established the concentration of γ-BHC non-phytocidal to sugar-beet seedlings. Later trials tested the effect on pre- and post-singling plant populations of dressings applied to natural or rubbed seed sown at standardized rates. Parallel tests of dressed seed were made on farms representing a variety of soil types, It was found that the phytotoxiCity of γ-BHC varied with season and soil type, but that a dressing containing 40 % was usually safe. In these trials, the benefits from seed dressing were, as a rule, slight. Generally the combined mercury-γ-BHC seed dressing gave the best pre-singling stand of plants. Most of the improvement was attributable to the organic mercury rather than to the γ-BHC, but where pest attacks occurred, γ-BHC gave marked improvements in stand. Wireworm appeared to be the chief pest controlled: control of pygmy mangold beetle was only partial.     

Root Formation on Petioles of Detached Primary Leaves of Dwarf Bean (Phaseolus vulgaris) Pretreated with Gibberellic Acid, Triiodobenzoic Acid, and Cytokinins

Rooting experiments carried out with isolated primary leavesof dwarf bean demonstrated the effect of GA on increasing theIAA level and IAA synthesis. Pretreatment of the lamina of isolatedleaves with GA, especially when tryptophane was added at thesame time, strikingly increased the rooting of petioles. Enhancedroot formation on the petiole of GA-pretreated leaves can beattributed to increase of IAA level by GA in the lamina, i.e.in IAA biosynthesis the utilization of tryptophane releasedfrom the proteins of isolated leaves is promoted by GA. Application of TIBA on the upper part of petiole suppressedthe stimulatory effect of GA on root initiation presumably becauseTIBA inhibits the transport of IAA into the petiole, which resultsin failure of rooting. Pretreatment of the leaves with cytokinins also results in failureof root production. These substances retard protein decompositionin isolated leaves so that the quantity of TPP available forauxin synthesis is less. Simultaneously, this treatment increasesthe cytokinin concentration in the leaf tissues so that theauxin/cytokinin ratio alters and mainly callus forms on thebase of the petioles and differentiation of root primordia cannottake place.     

Strengthening the Natural and National Park system of Iberia to conserve vascular plants

The diversity of the Iberian vascular flora has been investigated using WORLDMAP versions 3.08 and 3.18. Two data sets scoring plant distributions as presences within the Iberian Peninsula were compiled; one for 2133 species at 50 × 50 km grid and the other for 801 species at 10 × 10 km map grids. Patterns of biodiversity were determined using the diversity measures of species richness, range-size rarity and character richness diversity. Using the diversity measures, combined with an area selection method, maps of priority areas were calculated using iterative procedures. Near minimum sets (NMSs) for both scales were calculated. Comparison of the NMS for the 10 × 10 km grid with the near minimum set for existing reserves (NMSER) showed that at least 2% more of the land surface would be required above and beyond the existing protected area network, currently comprising 6% of the area, to ensure representation of all species at least once as listed within the present data-base. It is demonstrated that reserve systems selected on a variety of different criteria are suboptimal when compared to particular groups of target organisms with a definite goal of representation for conservation. Calculating efficiency of existing reserve systems and accounting for all taxa identifies precisely the extra required areas for the protected area system to satisfy particular goals of representation.     

Variation in abundance across a species' range predicts climate change responses in the range interior will exceed those at the edge: a case study with North American beaver

The absence of information about how abundance varies across species' ranges restricts most modeling and monitoring of climate change responses to the range edge. We examine spatial variation in abundance across the northeastern range of North American beaver ( Castor canadensis ), evaluate the extent to which climate and nonclimate variables explain this variation, and use a species–climate envelope model that includes spatial variation in abundance to predict beaver abundance responses to projected climate change. The density of beaver colonies across Québec follows a roughly logistic pattern, with high but variable density across the southern portion of the province, a sharp decline in density at about 49°N, and a long tail of low density extending as far as 58°N. Several climate and nonclimate variables were strong predictors of variation in beaver density, but 97% of the variation explained by nonclimate variables could be accounted for by climate variables. Because of the peak and tail density pattern, beaver climate sensitivity (change in density per unit change in climate) was greatest in the interior and lowest at the edge of the range. Combining our best density–climate models with projections from general circulation models (GCM) predicts a relatively modest expansion of the species' northern range limit by 2055, but density increases in the range interior that far exceed those at the range edge. Thus, some of the most dramatic responses to climate change may be occurring in the core of species' ranges, far away from the edge-of-the-range focus of most current modeling and monitoring efforts.