Добірка наукової літератури з теми "Pond ecology Victoria"

AbstractMeltwater habitats in the Darwin Glacier region, Victoria Land (80°S), were sampled in December 2007 and January 2009 to characterize their microbial and metazoan ecology, nutrient status and geochemistry. Targeted areas included terrestrial ponds of the Grant Valley, Lake Wellman, Tentacle Ridge and Diamond Hill, and supraglacial ponds and cryoconite holes of the lower Darwin Glacier. Geochemistry ranged from Na-Cl dominated terrestrial ponds to Na-HCO3dominated, dilute supraglacial ponds and cryoconites. All showed the nitrate enrichment typical of inland ponds of Victoria Land (up to 13 g.l-1NO3-N), with some precipitating nitratine (NaNO3) salt. Elevated pH indicated ongoing photosynthetic processes. Benthic microbial mats were thin and poorly developed, dominated by oscillatoriacean cyanobacteria. Nitrogen-fixing genera were generally absent and diatoms were rare. A large (20 μm long)Cyanothecespecies was the most abundant cyanobacterium in the water and in sediments of the cryoconites. DNA finger-printing identified distinct differences in cyanobacterial and bacterial community structure between the cryoconites, terrestrial ponds and ponds on glacial margins. Eleven metazoan species were identified, with rotifers being the most abundant. Pond substrate (terrestrial rock, ice-cored moraine or supraglacial ice) proved to be a more significant influence on biogeochemistry than other aspects of geography or climatic conditions.

AbstractMeltwater ponds are important biodiversity elements in continental Antarctica. Many occupy closed basins and are vulnerable to changes in the balance between water accrual, through melting of ice and snow, and water loss by ablation and evaporation. We use a two-decade long record of ponds on the McMurdo Ice Shelf to assess temporal variability in key limnological variables. Ponds underwent many-fold change in biologically conservative variables, such as conductivity, and changes were similar in ponds from different catchments but of comparable area. In contrast, biologically active variables (pH, inorganic nutrients and planktonic/benthic biomass) are buffered by in-pond processes and show consistency between years and no coherence across catchments. Coherent behaviour across catchments implies an overarching, climatic effect. However, we could identify no signature of summer air temperature or irradiance in pond dynamics, although winter snow deposition may leave a legacy of low conductivity to the following summer. While ponds are clearly affected by climate, our data show that ecosystem responses are complex and highlight the need for system-appropriate, long-term observation if directional environmental change is to be separated from inherent variability in systems that respond to multiple climatic variables and which have significant biological buffering capacity.

Lithium distributions in lake and pond waters of the McMurdo Dry Valleys of southern Victoria Land, Antarctica were studied to elucidate the origin of dissolved salts and the evolutionary history of the lakes and ponds. The EfLi [(Li/Cl)sample/(Li/Cl)seawater] values of the bottom waters in Lakes Bonney and Fryxell were higher than unity (EfLi=4–7), indicating that the salts originated from sea salts (probably relict seawater) and have been subsequently modified by the contribution of meltwaters containing atmospheric fallout and/or rock and soil weathering products. In contrast, extremely high Li concentrations with high EfLi values in the Don Juan Pond water (EfLi = 180) and the bottom waters of Lake Vanda (EfLi = 40) suggest that the salts originated from deep groundwaters influenced mainly by saline water-rock interactions, as supported by the dissolution experiments of granite in NaCl solution. The low Li concentrations of pond waters with high EfLi values in the Labyrinth indicate that the salts are derived from atmospheric fallout. The decrease of the EfLi values with the increase of Cl concentrations can be explained by the repeated cycles of the migration of Li into the ice phase and subsequent ablation of surface ice, as indicated by seawater freezing experiments.

The extensive ablation zone on the McMurdo Ice Shelf (78°S, 165°30′E) contains numerous ponds that are lined with benthic mats of cyanobacteria and associated micro-organisms. The photoautotrophic biomass content of these mats was examined in six contrasting ponds. Particulate carbon contributed only 3.2% of the mat dry weight, with C:N ratios generally less than 20:1. The chlorophyll a content was low relative to carbon (chlorophylla : C<0.01). Analysis of the mats by high performance liquid chromatography [HPLC] showed that the pigment fraction assayed spectrophotometrically as chlorophyll a contained large quantities (up to 70%) of the degradation product chlorophyllide a and the epimer chlorophyll a'. Photosynthetic rates per unit chlorophyll a[HPLC] were extremely slow: <0.1 mg C (mg Chla)−1, less than one tenth the rates recorded in the overlying phytoplankton community. These analyses indicate that in the ice pond benthic mats most of the dry weight is inorganic, most of the organic carbon is non-chlorophyll-containing material, and much of the chlorophyll a is not photosynthetically active. Cold temperatures and the associated low activity of herbivores and detritivores may contribute towards this preservation of inactive chlorophyll a on the McMurdo Ice Shelf, and perhaps in similar benthic mats in the lakes and streams of southern Victoria Land.

Five taxa in the genus Neidium, N. iridis, N. beatyi sp. nov., N. vandusenense sp. nov., N. collare sp. nov. and N. lavoieanum sp. nov. are documented from a pond and stream system in the VanDusen Botanical Garden, Vancouver, Canada. Neidium beatyi is a large linear species with multiple longitudinal canals and sagittate apices. The areolae are occluded by finger-like silica extensions on the external surface. This taxon is distinguished from Neidium iridis by the number of longitudinal canals (>5), shape of the valve apices, and smaller size. Neidium vandusenense is broadly linear with distinct rostrate apices. Two-three longitudinal canals are present along each margin. Plastid rbcL sequence data associates this taxon with N. amphigomphus. Neidium collare is an elliptic lanceolate taxon with one longitudinal canal. This taxon is genetically related to N. bisculatum sensu lato, but with a different shape form. Neidium lavoieanum has a valve shape form similar to Neidium potapovae, but is larger and genetically similar to N. productum sensu lato. The five Neidium taxa were observed in a small stream next to Lake Victoria (pond) in the VanDusen Botanical Garden Vancouver, Canada. The water was mildly alkaline with a pH of 7.86, a conductance of 163 µS/cm, higher nutrient loads and low metal content.

Aquatic ecosystems around the world have been massively altered through vegetation clearance and changed flow regimes accompanying agricultural development. Impacts may include disrupted dispersal for aquatic species. We investigated this in lentic (standing) waterbodies in agricultural and predominantly forested landscapes of the box-ironbark region of central Victoria, Australia. We hypothesised that higher representation in forested than agricultural landscapes (i.e. ‘forest-bias’) for a species may reflect an ability to disperse more easily through the former, resulting in lower genetic structure in forested than in agricultural landscapes. Conversely, ‘cosmopolitan’ species would show no difference in genetic structure between landscape types. Molecular genetic analyses of a forest-biased diving beetle, Necterosoma wollastoni, and a cosmopolitan waterboatman, Micronecta gracilis, revealed the following, for both species: (1) no evidence for long-term barriers to gene flow in the region, (2) lack of contemporary genetic differentiation over 30 000 km2 and (3) random distribution of related genotypes in space, implying that neither forest nor farmland inhibits their dispersal in a concerted fashion. Taken together, these results indicate very high gene flow and dispersal in the past and present for both these species. Massive landscape change may have little impact on movement patterns of lentic invertebrates that have evolved high dispersal capabilities.

The Australian species of the water beetle genus Hydraena Kugelann, 1794, are revised, based on the study of 7,654 specimens. The 29 previously named species are redescribed, and 56 new species are described. The species are placed in 24 species groups. High resolution digital images of all primary types are presented (online version in color), and geographic distributions are mapped. Male genitalia, representative female terminal abdominal segments and representative spermathecae are illustrated. Australian Hydraena are typically found in sandy/gravelly stream margins, often in association with streamside litter; some species are primarily pond dwelling, a few species are humicolous, and one species may be subterranean. The areas of endemicity and species richness coincide quite closely with the Bassian, Torresian, and Timorian biogeographic subregions. Eleven species are shared between the Bassian and Torresian subregions, and twelve are shared between the Torresian and Timorian subregions. Only one species, H. impercepta Zwick, is known to be found in both Australia and Papua New Guinea. One Australian species, H. ambiflagellata, is also known from New Zealand. New species of Hydraena are: H. affirmata (Queensland, Palmerston National Park, Learmouth Creek), H. ambiosina (Queensland, 7 km NE of Tolga), H. antaria (New South Wales, Bruxner Flora Reserve), H. appetita (New South Wales, 14 km W Delagate), H. arcta (Western Australia, Synnot Creek), H. ascensa (Queensland, Rocky Creek, Kennedy Hwy.), H. athertonica (Queensland, Davies Creek), H. australula (Western Australia, Synnot Creek), H. bidefensa (New South Wales, Bruxner Flora Reserve), H. biimpressa (Queensland, 19.5 km ESE Mareeba), H. capacis (New South Wales, Unumgar State Forest, near Grevillia), H. capetribensis (Queensland, Cape Tribulation area), H. converga (Northern Territory, Roderick Creek, Gregory National Park), H. cubista (Western Australia, Mining Camp, Mitchell Plateau), H. cultrata (New South Wales, Bruxner Flora Reserve), H. cunninghamensis (Queensland, Main Range National Park, Cunningham's Gap, Gap Creek), H. darwini (Northern Territory, Darwin), H. deliquesca (Queensland, 5 km E Wallaman Falls), H. disparamera (Queensland, Cape Hillsborough), H. dorrigoensis (New South Wales, Dorrigo National Park, Rosewood Creek, upstream from Coachwood Falls), H. ferethula (Northern Territory, Cooper Creek, 19 km E by S of Mt. Borradaile), H. finniganensis (Queensland, Gap Creek, 5 km ESE Mt. Finnigan), H. forticollis (Western Australia, 4 km W of King Cascade), H. fundaequalis (Victoria, Simpson Creek, 12 km SW Orbost), H. fundata (Queensland, Hann Tableland, 13 km WNW Mareeba), H. hypipamee (Queensland, Mt. Hypipamee National Park, 14 km SW Malanda), H. inancala (Queensland, Girraween National Park, Bald Rock Creek at "Under-ground Creek"), H. innuda (Western Australia, Mitchell Plateau, 16 mi. N Amax Camp), H. intraangulata (Queensland, Leo Creek Mine, McIlwrath Range, E of Coen), H. invicta (New South Wales, Sydney), H. kakadu (Northern Territory, Kakadu National Park, Gubara), H. larsoni (Queensland, Windsor Tablelands), H. latisoror (Queensland, Lamington National Park, stream at head of Moran's Falls), H. luminicollis (Queensland, Lamington National Park, stream at head of Moran's Falls), H. metzeni (Queensland, 15 km NE Mareeba), H. millerorum (Victoria, Traralgon Creek, 0.2 km N 'Hogg Bridge', 5.0 km NNW Balook), H. miniretia (Queensland, Mt. Hypipamee National Park, 14 km SW Malanda), H. mitchellensis (Western Australia, 4 km SbyW Mining Camp, Mitchell Plateau), H. monteithi (Queensland, Thornton Peak, 11 km NE Daintree), H. parciplumea (Northern Territory, McArthur River, 80 km SW of Borroloola), H. porchi (Victoria, Kangaroo Creek on Springhill Rd., 5.8 km E Glenlyon), H. pugillista (Queensland, 7 km N Mt. Spurgeon), H. queenslandica (Queensland, Laceys Creek, 10 km SE El Arish), H. reticuloides (Queensland, 3 km ENE of Mt. Tozer), H. reticulositis (Western Australia, Mining Camp, Mitchell Plateau), H. revelovela (Northern Territory, Kakadu National Park, GungurulLookout), H. spinissima (Queensland, Main Range National Park, Cunningham's Gap, Gap Creek), H. storeyi (Queensland, Cow Bay, N of Daintree River), H. tenuisella (Queensland, 3 km W of Batavia Downs), H. tenuisoror (Australian Capital Territory, Wombat Creek, 6 km NE of Piccadilly Circus), H. textila (Queensland, Laceys Creek, 10 km SE El Arish), H. tridisca (Queensland, Mt. Hemmant), H. triloba (Queensland, Mulgrave River, Goldsborough Road Crossing), H. wattsi (Northern Territory, Holmes Jungle, 11 km NE by E of Darwin), H. weiri (Western Australia, 14 km SbyE Kalumburu Mission), H. zwicki (Queensland, Clacherty Road, via Julatten).