The Impact of Simulated Acid Rain and Fertilizer Application on a Mature Sugar Maple (Acer Saccharum Marsh.) Forstt in Central Ontario Canada

The effects of two year's addition of simulated acid precipitation, with and without added fertilizer, on mycorrhizae, litter decomposition and soil and tree chemistry in a sugar maple (Acer saccharum Marsh.) dominated forest were investigated. The forest floor beneath mature sugar maple trees was irrigated at monthly intervals between May and September with local lake water acidified to pH 3, pH 4 or untreated lakewater of pH 4.9. In addition, a commercial organic slow-release fertilizer (Maple Gro) was added to the soil prior to irrigation with pH 3 spray. Trees to which no experimental spray was applied were also included as controls. Eight trees were used for each of the five treatments. Application of the acid spray alone did not acidify surface soil nor cause visible symptoms of decline in trees. The pH of the soil solution and soil leachate was increased by addition of acidified lakewater. An increase in the concentration of sulphate (SO₄ ^2-), calcium (Ca), and magnesium (Mg) in soil leachate was only recorded in plots irrigated with water acidified to pH 3 + Maple Gro. The initial rate of litter decomposition tended to be higher following application of the acid sprays, although mycorrhizal infection of sugar maple roots was reduced in the pH 3 and pH 4 treatments. Concentrations of zinc (Zn), chromium (Cr) and nickel (Ni) were highest in wood formed during the period irrigated with water acidified to pH 3. Foliar nitrogen (N) concentrations tended to be higher in all irrigated treatments, although there were no differences between treatment in any of the other nutrients measured in foliage after two years of treatment. It is concluded that the application of simulated acid rain under field conditions results in a complex interaction of events which are not reproduced in pot trials and must be fully understood before the impact of acid rain on sugar maple forests can be evaluated.     

Root characteristics of temperate pasture in New South Wales after grazing at three stocking rates for 30 years

The distribution of length, diameter, surface area and volume of roots was measured in northern New South Wales, Australia, under temperate pasture that had been previously grazed at low and high stocking rates for 30 years; these root characteristics were compared with those of roots under ungrazed pasture. The ungrazed pasture was dominated by Phalaris (Phalaris Aquatica), whereas annual grasses and dicotyledons were a large component of the pasture at low and high stocking rates. A fine-meshed (0.250 mm) sieve was used for separating the roots from the soil, and the root characteristics were measured using image analysis techniques. With this sieve size, root length densities were many times higher than published data for astures where a larger mesh sieve had been used for sample preparation. The lengths of root per unit of soil volume (root length densities) were high for all stocking rates and averaged 91 cm cm^?3 near the soil surface (0 – 5 cm) declining to 4.0 cm cm^?3 at the deepest depth measured (65–75 cm). There was a greater proportion of roots near the soil surface at the higher stocking rates. A greater proportion of fine roots occurred at the higher stocking rates, which was probably due to the differences in botanical composition. Reciprocal, power and logarithmic functions best described the distribution of root length density, root surface area density and root volume density, root surface area density and root volume desnity with depth.     

Single-grain 40Ar-39Ar ages of glauconies: implications for the geologic time scale and global sea level variations

The mineral series glaucony supplies 40% of the absolute-age database for the geologic time scale of the last 250 million years. However, glauconies have long been suspected of giving young potassium-argon ages on bulk samples. Laser-probe argon-argon dating shows that glaucony populations comprise grains with a wide range of ages, suggesting a period of genesis several times longer ( approximately 5 million years) than previously thought. An estimate of the age of their enclosing sediments (and therefore of time scale boundaries) is given by the oldest nonrelict grains in the glaucony populations, whereas the formation times of the younger grains appear to be modulated by global sea level.     

The effects of temperature and food ration on metabolite concentrations in newly settled king scallop (Pecten maximus) spat

Juvenile king scallop (Pecten maximus L.) between 0.2 and 1.5 g wet shell weight per individual, reared at 10, 14 and 17 °C, were fed either a full ration equivalent to 0.5 g (ash-free dry weight of algae) g^− 1 (live weight of spat) week^− 1 or a restricted algal ration of 0.07 g (ash-free dry weight of algae) g^− 1 (live weight of spat) week^− 1. The algal food was a mixture of two microalgal species: Chaetoceros ceratosporum (Droop) Green and Pavlova lutheri Ostenfeld. Measurements were made of tissue concentrations of adenylate tri-, di- and mono-phosphate, lactate, succinate, acetate, pyruvate and l-alanine. The metabolite measurements were used as indicators of viability in animals exposed to a matrix of temperature and food supply conditions. It was found that the variations in metabolic responses could be correlated with those observed in a previous study that measured body condition in relation to the same set of variables. It was also found that the data from the present study were most strongly influenced by temperature-related effects and that there was an optimal temperature range between 10 and 14 °C. The metabolic responses, measured in terms of metabolite concentrations, would seem to confirm the existence of a bi-stable physiology in P. maximus in which there is a switch in state between 10 and 14 °C.     

Responses of digestive enzymes and body lipids to weaning times in yellowtail kingfish Seriola lalandi (Valenciennes, 1833) larvae

The optimal time to wean fish larvae from live feed to artificial feed was explored in yellowtail kingfish Seriola lalandi (YTK). The same weaning regime started at five different days post hatching (DPH), namely 10 DPH (W10), 13 DPH (W13), 16 DPH (W16), 19 DPH (W19) and 22 DPH (W22). The activities of trypsin, lipase and alkaline phosphatase were detected in fish from 8 DPH throughout the experiment, but pepsin activity was first detected in fish on 15 DPH in the W10 and W13 treatments. The increase in pepsin activity was concomitant with the decrease in trypsin activity. Total fish lipids after weaning reduced by 40% in the W10 and W13 treatments, and increased by 20% in the W19 and W22. Fish survival rate in the W22 treatment was significantly higher than that in the W10 and W13 treatments. The results suggest that 16 DPH is the earliest day to wean and the best weaning window for YTK larvae should be 19–22 DPH. This study provides enzymatic evidence to guide the weaning process for YTK larvae, and offers a useful approach to explore optimal weaning time for fish larvae.     

Effects of diets on the growth performance and shell pigmentation of Pacific abalone

This study investigated the effects of natural and artificial diets on growth performance and shell pigmentation of cultured abalone. A 7‐month feeding trial was conducted on 12 000 Pacific abalones (Haliotis discus hannai) with four diets including two extruder‐processed test diets (with & without addition of oleopaprika carotenoids), Pacific dulse (Palmaria mollis) and a combination of Pacific dulse and a test diet. The results showed that the two test diets resulted in higher survival of abalone, but with a lower growth rates when compared with Pacific dulse alone (P < 0.05). The combination diet achieved the highest survival and growth rates. The Pacific dulse resulted in abalone with dark‐brown shells, which are preferred by Asian markets. The test diets led to 52% and 55% of the animals with pink coloured shells and the supplementation of oleopaprika did not affect shell pigmentation. The aqueous acidic extracts from both dark‐brown and pink shells showed blue colour; HPLC‐MS chromatography revealed that the pigments in the extracts were consistent with a biliverdin and a cysteine‐biliverdin. These results are valuable for the development of abalone feed and the control of abalone shell colouration.     

Landscape patterns and diversity of meadow plants and flower-visitors in a mountain landscape

Context

Wild flowering plants and their wild insect visitors are of great importance for pollination. Montane meadows are biodiversity hotspots for flowering plants and pollinators, but they are contracting due to tree invasion.

Objectives

This study quantified flowering plants and their flower-visitor species in montane meadows in the western Cascade Range of Oregon. Species diversity in small, isolated meadows was expected to be lower and nested relative to large meadows. Alternatively, landform features may influence richness and spatial turnover.

Methods

Flowering plants and their visitors were sampled in summers of 2011–2017 in twelve montane meadows with varying soil moisture. All flowering plants and all flower-visitors were recorded during five to seven 15 min watches in ten 3?×?3 m plots in each meadow and year.

Results

A total of 178 flowering plant species, 688 flower-visitor species and 137,916 interactions were identified. Richness of flower-visitors was related to meadow patch size, but neither plant nor flower-visitor richness was related to isolation measured as meadow area within 1000 m. Species in small meadows were not nested subsets of those in large meadows. Species replacement accounted for more than 78% of dissimilarity between meadows and was positively related to differences in soil moisture.

Conclusions

Although larger meadows contained more species, landform features have influenced meadow configuration, persistence, and soil moisture, contributing to high plant and insect species diversity. Hence, conservation and restoration of a variety of meadow types may promote landscape diversity of wild plants and pollinators.

     

From flat foot to fat foot: structure, ontogeny, function, and evolution of elephant "sixth toes"

Several groups of tetrapods have expanded sesamoid (small, tendon-anchoring) bones into digit-like structures ("predigits"), such as pandas' "thumbs." Elephants similarly have expanded structures in the fat pads of their fore- and hindfeet, but for three centuries these have been overlooked as mere cartilaginous curiosities. We show that these are indeed massive sesamoids that employ a patchy mode of ossification of a massive cartilaginous precursor and that the predigits act functionally like digits. Further, we reveal clear osteological correlates of predigit joint articulation with the carpals/tarsals that are visible in fossils. Our survey shows that basal proboscideans were relatively "flat-footed" (plantigrade), whereas early elephantiforms evolved the more derived "tip-toed" (subunguligrade) morphology, including the predigits and fat pad, of extant elephants. Thus, elephants co-opted sesamoid bones into a role as false digits and used them for support as they changed their foot posture.     

Neighborhood-level socioeconomic and urban land use risk factors of canine leptospirosis: 94 cases (2002-2009)

Associations of housing, population, and agriculture census variables, and presence near public places were retrospectively evaluated as potential risk factors for canine leptospirosis using Geographic Information Systems (GIS). The sample population included 94 dogs positive for leptospirosis based on a positive polymerase chain reaction test for leptospires on urine, isolation of leptospires on urine culture, a single reciprocal serum titer of 12,800 or greater, or a four-fold rise in reciprocal serum titers over a 2-4 week period; and 185 dogs negative for leptospirosis based on a negative polymerase chain reaction test and reciprocal serum titers less than 400. Multivariable logistic regressions revealed different risk factors among different census units; however, houses lacking complete plumbing facilities [OR=2.80, 95% C.I.=1.82, 4.32 (census unit, block group); OR=1.36, 95% C.I.=1.28, 1.45 (census tract); OR=3.02, 95% C.I.=2.60, 3.52 (county)]; and poverty status by age (18-64) [OR=2.04, 95% C.I.=1.74, 2.39 (block group); OR=1.53, 95% C.I.=1.41, 1.67 (census tract); and OR=1.62, 95% C.I.=1.50, 1.76 (county)] were consistent risk factors for all census units. Living within 2500m of a university/college and parks/forests were also significantly associated with leptospirosis status in dogs. Dogs that live under these circumstances are at higher risk for leptospirosis and pet owners should consider vaccination.