Is the decline of birds and amphibians in a steppe lake of northern Patagonia a consequence of limnological changes following fish introduction?

• 1. Laguna Blanca, in Laguna Blanca National Park, is a lake in Patagonia which has been designated as a Ramsar site since 1971 because of bird diversity and abundance and importance for nesting, particularly for the black neck swan, Cygnus melanocoryphus. It is also valued for its populations of endemic amphibians, Atelognathus patagonicus and Atelognathus praebasalticus.
• 2. Avian and amphibian populations have decreased dramatically in recent years. Percichthys colhuapiensis, Percichthys trucha (Pisces, Percichthyidae), Salmo trutta and Oncorhynchus mykiss (Pisces, Salmonidae) were introduced into Laguna Blanca in 1965. Since 1986, no Atelognathus frogs have been found. The abundance of swans and coots, which are strongly associated with macrophytes for nesting and feeding, has diminished drastically, whereas piscivorous birds have increased.
• 3. The fishless condition of some neighbouring small lakes with abundant pond weeds, aquatic birds and endemic amphibians, was assessed in order to compare the physical and chemical characteristics and the quantitative composition of the benthos among lakes. Fish presence at Laguna Blanca and its absence at El Burro, Antiñir and Jabón lakes, were confirmed. Compared with previous results, it seems that the abundance of Amphipoda (Hyalella), Copepoda and Cladocera at Laguna Blanca has decreased, while Acari has increased and Notostraca has disappeared. Water transparency has diminished in Laguna Blanca and now is lower than that of fishless lakes.
• 4. P. colhuapiensis were captured only in Laguna Blanca, with the highest captures in the littoral zone. The population shows rapid individual growth in the early years and an absence of fish older than 6 years. The preponderance of benthos and the presence of macrophytes in the gut contents of adult P. colhuapiensis appear to indicate that they are important consumers of these resources.
• 5. This paper concludes that fish introduction in Laguna Blanca led to a complex trophic cascade effect (fish predation on tadpoles, fish competition for avian food, bottom disturbance, zooplankton reduction) producing deleterious effects on the amphibian and bird populations.

Copyright © 2006 John Wiley & Sons, Ltd.     

Enhanced resistance to bacterial infection byErwinia carotovora subsp.atroseptica in transgenic potato plants expressing the attacin or the cecropin SB-37 genes

Blackleg and soft rot diseases, caused by the bacteriumErwinia carotovora, are among the diseases that cause important losses in culture and storage of potato. In this paper, we introduced bacterial resistance into potato, via genes encoding for proteins with antibacterial activity. For this purpose, potato clones were transformed either with the gene encoding the acidic attacin protein fromHyalophora cecropia, or with the gene encoding the cecropin analog peptide SB37. These clones were evaluated for soft rot and blackleg resistance, after inoculation with the bacterial strainErwinia carotovora subsp.atroseptica T7. Results reported in this paper indicate that a considerable percentage of the potato clones (15–22%) showed increased resistance to bacterial infection, revealed by reduced severity of blackleg or soft rot symptoms. Expression of the transgenes was demonstrated in some of the clones by Northern blot analysis. This is the first report indicating that expression of the gene encoding for an attacin protein and for the cecropin SB-37 peptide in transgenic potato confers increased resistance to bacterial infection.     

Climate Variability and Oceanographic Settings Associated with Interannual Variability in the Initiation of Dinophysis acuminata Blooms

In 2012, there were exceptional blooms of D. acuminata in early spring in what appeared to be a mesoscale event affecting Western Iberia and the Bay of Biscay. The objective of this work was to identify common climatic patterns to explain the observed anomalies in two important aquaculture sites, the Galician Rías Baixas (NW Spain) and Arcachon Bay (SW France). Here, we examine climate variability through physical-biological couplings, Sea Surface Temperature (SST) anomalies and time of initiation of the upwelling season and its intensity over several decades. In 2012, the mesoscale features common to the two sites were positive anomalies in SST and unusual wind patterns. These led to an atypical predominance of upwelling in winter in the Galician Rías, and increased haline stratification associated with a southward advection of the Gironde plume in Arcachon Bay. Both scenarios promoted an early phytoplankton growth season and increased stability that enhanced D. acuminata growth. Therefore, a common climate anomaly caused exceptional blooms of D. acuminata in two distant regions through different triggering mechanisms. These results increase our capability to predict intense diarrhetic shellfish poisoning outbreaks in the early spring from observations in the preceding winter.     

Benchmarking sunflower water productivity in semiarid environments

Appropriate benchmarking is essential for evaluating the efficiency with which crops use water and for identifying constraints, other than water, to crop yield. No benchmark exists for sunflower. Boundary and simulation analyses were used to quantify the water productivity of sunflower crops grown in the Western Pampas (semiarid central Argentina). The approach involved the use of a large database (n = 169) collected in farmers’ fields over a period of 4 years, and the application of a crop simulation model in combination with actual weather and soil data. Using field data, an upper bound of 8 kg grain ha⁻¹ mm⁻¹ for water productivity, with an apparent seasonal soil evaporation of 75 mm, was defined. Seasonal water supply exceeded maximum expected seasonal crop requirements (ca. 630 mm) for many crops, and a majority of crops with <630 mm of available water during the season had water productivities considerably lower than the upper bound. The field data-based upper bound was indistinguishable from that obtained using yields for a set of 47 simulations using observed initial values for soil water and nitrogen profiles. Simulation confirmed the main features of the boundary-analysis applied to field data, and many simulated crops had yields that fell below the boundary function, even when simulated yield was plotted against simulated seasonal evapotranspiration or transpiration. Long-term (33-year) simulation analyses for two sites showed that most sunflower crops in the area are subjected to episodes of transient and unavoidable water stress after floral initiation. High levels of available soil water at sowing moderate, but in most years do not eliminate, these exposures to water stress. Yield gaps with respect to the boundary function were associated with deficient or excessive rainfall during grain filling, and other, non-water related, factors such as inadequate crop nutrition, biotic stresses, low photothermal quotients during the interval close to anthesis, and lodging. A grain yield/seasonal evapotranspiration plot for a large (n = 154) data set from experiments conducted by others in five separate environments suggests that the boundary function found for the Western Pampas is broadly applicable. Sunflower water productivity, corrected for oil-synthesis costs and seasonal vapour pressure deficit differences, approximates that of winter cereals grown in Mediterranean environments.     

High prevalence of intestinal zoonotic parasites in dogs from Belgrade, Serbia--short communication

To identify areas of risk for canine-related zoonoses in Serbia, the aim of this study was to provide baseline knowledge about intestinal parasites in 151 dogs (65 household pets, 75 stray and 11 military working dogs) from Belgrade. The following parasites, with their respective prevalences, were detected: Giardia duodenalis (14.6%), Ancylostomatidae (24.5%), Toxocara canis (30.5%), Trichuris vulpis (47.0%) and Taenia-type helminths (6.6%). Of all examined dogs, 75.5% (114/151) were found to harbour at least one parasite species. Of these, mixed infections with up to four species per dog occurred in 44.7% (51/114). Infections with all detected species were significantly higher (p < 0.05) in military working (100%) and stray dogs (93.3%) versus household pets (50.8%). Among all parasites, agents with zoonotic potential including Giardia, Ancylostomatidae and Toxocara were detected in 58.3% (88/151) of all examined dogs with a significant difference (p < 0.05) among the subgroups (100%, 62.7% and 46.2% for military working dogs, stray dogs and household pets, respectively). The high prevalence of zoonotic parasites registered in the dog population from a highly urban area in south-eastern Europe indicates a potential risk to human health. Thus, veterinarians should play an important role in helping to prevent or minimise zoonotic transmission.     

Vergleichende Untersuchungen an Haaren von Pudu pudu und europäischen Cerviden

The awn and the fur hair of Pudu were investigated. Values of the length are between 14 and 56 mm for the awn hair, and 9 to 36 mm for the fur hair. Hair thickness--especially at the thickest point--ranges from 140 to 236 microns for the awn hair and from 19 to 106 microns for the fur hair. The values of the cuticle scales are between 12 and 18 microns for the length and between 41 and 66 microns for the width. The shape of the scales is rectangular in the basal three quarters (R) and becomes crenated (R/Z) in the apical quarter. The medulla is continuous with large hollow vesicles. The similarity to the hair of european red deer is surprising.     

Chemical control of Delia platura in Phaseolus vulgaris with seed and soil treatments in Chile

A field trial with beans (Phaseolus vulgaris L.) was performed in the Santiago area, to evaluate the insecticidal effect of aldrin, carbofuran, chlorpyriphos, diazinon and lindane, applied to the seed or to the seed furrow, against the bean fly, Delia platura Meigen (Diptera, Anthomyiidae). Plant emergence was reduced with carbofuran and diazinon as a seed treatment, and chlorpyriphos in the furrow, in relation to the checks. All insecticidal treatments reduced the damage to the plants, demonstrating the value of using insecticides for controlling this pest.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

Genetic structure of highland papayas (<Emphasis Type="Italic">Vasconcellea pubescens</Emphasis> (Lenné et C. Koch) Badillo) cultivated along a geographic gradient in Chile as revealed by Inter Simple Sequence Repeats (ISSR)

In Chile Vasconcellea pubescens is cropped to produce canned fruit, juice, jam and processed sweets. Additionally this species produces latex with a high level of papain, an important and valuable proteolytic enzyme with industrial applications. In this investigation seven ISSR primers were used to study the level and organization of genetic diversity in 333 samples of V. pubescens. Out of the 114 bands recorded, 63 proved to be polymorphic (P = 55.3%). At the species level, the genetic diversity was rather low (h = 0.01 ± 6,80188E-05, Shannon’s Index I = 0.16 ± 0,000148). The major portion of the genetic diversity was found within groups (65%). The genetic differentiation between the different groups was significant, as the AMOVA analysis suggested (Φ_pt = 0.35). When analysing the Northern area alone, the differentiation increased to Φ_pt = 0.40. When only the Southern area was analysed, Φ_pt decreased to 0.18, indicating greater genetic similarity among the samples. The results generated from Structure and Bayesian Analysis of Population Structure distinguished 8 genetically different groups, five of them located in the north and three in the south. The results are discussed in the light of the growers’ practices.     

Boron increases pollen quality,pollination, and fertility of different genetic lines of pepper

Using different genetic lines of pepper, this study analyses the effect of boron (B) on pollen quality and its capacity to pollinate and fertilize. Three different B concentrations (100, 150, and 200 mg L^?1) were applied to six genetic lines, evaluating the in vitro pollen quality and pollen formation. In a second experiment, the highest and the lowest B concentrations were applied to two low-pollen genetic lines, evaluating the growth of the pollen tubes in flowers pollinated with treated pollen. The higher B concentrations significantly improved pollen quality and formation in vitro, while improved pollination and fecundity was observed after monitoring the pollen tubes. For all variables, the specific genetic line also showed some effect. This technique represents a tool for improving pollen in manual hybrid seed programs.