Foliage Substrates Research Articles

Research on self-purification capacity of Lake Taihu.

An effective measure to cope with eutrophication of lakes is to remove nutrients that can cause algal blooming by taking advantage of natural water purification processes. Here, the term "purification" is defined, in a wide sense, as the potential role of a water body to contribute to the reduction of pollutants and thus controlling eutrophication. Also regarded as a kind of ecological regulating services, biological purification involves various processes concerning seasonal nutrient fixation, such as uptake by aquatic macrophyte, biofouling onto foliage substrates, feeding by organisms in higher trophic level, and eternal loss or removal of substance from the water. In order to evaluate the water purification ability, a numerical lake ecosystem model (EcoTaihu) was developed and applied to Lakes Taihu. The model includes the biological interactions between pelagic compartments (phytoplankton and zooplankton, detritus, dissolved organic matter, fish, and nutrients). Under dynamic forcing of meteorological and hydrological parameters, the model was run over years to evaluate the annual nutrient cycles and purification functions. The reproducibility of the model was validated for water body by comparison with the field data from the water quality monitoring campaign. Numerical results revealed that self-purification capacity of nitrogen of Lake Taihu in years 2006, 2008, and 2010 is 4.00 × 10(4), 4.27 × 10(4), and 4.11 × 10(4)ton, respectively, whereas self-purification capacity of phosphorus of Lake Taihu in years 2006, 2008, and 2010 is 1.56 × 10(3), 1.80 × 10(3), and 1.71 × 10(3)ton, respectively.

Evaluation of biological water purification functions of inland lakes using an aquatic ecosystem model

An effective measure to cope with eutrophication of lakes is to remove nutrients that can cause algal blooming by taking advantage of natural water purification processes. Here the term “ purification” is defined, in a wide sense, as the potential role of a water body to contribute to the reduction of pollutants and thus controlling eutrophication. Also regarded as a kind of ecological regulating services, biological purification involves various processes concerning seasonal nutrient fixation, such as uptake by aquatic macrophytes, biofouling onto foliage substrates, feeding by organisms in higher trophic level, and eternal loss or removal of substance from the water. In order to evaluate the water purification ability, a numerical lake ecosystem model highlighting the role of macrophyte colonies in the shore zone was developed and applied to Lakes Suwa, Kasumi and Biwa, as well as five small lakes attached to Lake Biwa. The model includes the biological interactions between pelagic compartments (phyto- and zooplankton, detritus, dissolved organic matter, pelagic fish and nutrients) and benthic compartments (macrophytes, epiphytic algae, phytal animals, macro- and megalobenthos, and demersal fish). Under dynamic forcing of meteorological and hydrological parameters, the model was run over a year to evaluate the annual nutrient cycles and purification functions. The reproducibility of the model was validated for each water body by comparison with the field data from the water quality monitoring campaign. Numerical results revealed that the water purification ability, from viewpoints of both stock and flux, generally tends to be higher in the shore region than in the offshore region owing to a wide variety of aquatic biota. Moreover, it increases almost in proportion to the density of vegetation in the shore region. Nutrient fluxes representing the purification processes turned out to be closely connected with the surface area or equivalently with the retention time of the water bodies, suggesting that biological purification does not become dominant against physical turnover until the surface area reaches around 10 3 ha or the retention time exceeds the order of 10 2 days.

Habitat use and foraging behaviour of the scarlet robin and the flame robin at a site of breeding-season sympatry

The habitat selection and foraging ecology of scarlet robins (Petroica multicolor) and flame robins (Petroica phoenicea) were observed for three years at a site of breeding-season sympatry in order to examine seasonal patterns of foraging behaviour, habitat and resource use, and the significance of competition for food as a cause of interspecific aggression. Both species occupied habitats with open ground layers of grass or bark, and a sparse shrub-and-sapling layer. Flame robins occupied more mesic habitats; scarlet robins occurred in drier habitats. Seven habitat variables provided 73% separation between habitats occupied by the two species of robin. Both species foraged mostly on the ground during the cooler months. In summer and autumn, scarlet robins became snatchers of arthropods from bark and foliage substrates, and flame robins hawked for flying insects close to the ground. High overlap between their use of available foraging space, especially vertical foraging space, probably caused interspecific competition for food and space, leading to interspecific aggression and territorial behaviour. Such competition, in conjunction with the flame robin's interspecific dominance and apparently greater resilience to practices such as timber harvesting, may cause long-term changes to the distribution and relative abundance of each species. Recommendations for habitat management are considered briefly.

Liquid Chromatographic Method for Quantitation of Glyphosate and Metabolite Residues in Organic and Mineral Soils, Stream Sediments, and Hardwood Foliage

A liquid chromatographic method for determining glyphosate (GLYPH) and its major metabolite aminomethylphosphonic acid (AMPA) in various environmental substrates is described. Ion-exchange column chromatography is coupled with post-column ninhydrin derivatization and absorbance detection at 570 nm. Use of a valve-switching technique allowed quantitation of both analytes in a single chromatographic run and eliminated slow-eluting, coextracted interferences. The method was successfully used to quantitate GLYPH and AMPA in organic and mineral soils, stream sediments, and foliage of 2 hardwood brush species. Mean recovery efficiencies for GLYPH as determined from fortified blank field samples were as follows: bottom sediment 84%, suspended sediment 66%, organic soils 79%, mineral soils 73%, alder leaf litter 81%, salmonberry leaf litter 84%, and artificial deposit collectors 87%. Precision for GLYPH determination was good with less than 14% coefficient of variation on mean recovery for all substrates. Limits of detection were lowest for sediments (0.01 microgram/g dry mass) and highest for foliage substrates (0.10 microgram/g dry mass). Using this system, 6 samples/person/day were routinely analyzed.

Food availability for forest birds: effects of prey distribution and abundance on bird foraging

To evaluate availability of food for passerine birds in a northern hardwood forest, we measured the abundance and distribution of Lepidoptera larvae, a major food type, on the foliage of the dominant tree species and the foraging behaviour used by birds to capture prey from foliage substrates. Larval abundances averaged 2.1 per 400-leaf sample, and differed significantly among tree species and strata and within and between years. Although American beech had significantly higher larval densities, yellow birch hosted a greater proportion of free-living larvae, which were more readily available to foraging birds. Most larvae (78–91%) were found on leaf blades, with 62–75% on leaf undersurfaces. Bird species differed significantly in the frequencies at which they attacked prey on different foliage substrates (upper or lower leaf surfaces, petioles, twigs) and tree species. Several changed their foraging patterns from one tree species to another. Six of the 10 bird species directed attacks to substrates in proportion to the abundance of larvae there; the other 4 deviated from this pattern because of preferences for other kinds of prey or because of different abilities to perceive and capture prey from trees with differing foliage structures. Our results suggest that availability of food for forest birds is a function of (i) the types and abundances of prey present, which vary among tree species, (ii) the foliage structure and characteristics of the trees, which influence prey detectability and accessibility, and (iii) the morphological and behavioural abilities of each bird species to perceive and capture those prey. Food availability therefore cannot be assessed by simply measuring prey abundance alone and must essentially be determined separately for each bird species. Since each tree species provides a differing set of foraging opportunities for birds, the mix of tree species at a site, coupled with the arthropod resources they support, will influence which bird species can successfully exploit that habitat and hence will affect bird community structure.