ERA Sciences Peer Reviewed Papers and Journal Articles

Critiquing the school community: a qualitative study of children’s conceptualizations of their school

Julie Ann Pooley et al. — Mon, 12 Apr 2010 19:53:01 PDT

Schools are traditionally seen as responsible for the educational outcomes of our children. However, schools also play an important role in the development of aspects such as self-efficacy, participation, competence and self-determination. As schools are often run as societies rather than communities, they offer little opportunity for these attributes (self-efficacy, participation, competence and self-determination) to develop. Forty-six children aged from nine to 12 years were interviewed to ascertain their conceptualizations of the school community. The children define their school in terms of people, places for activities and interaction, a place for safety, cooperation, influence and functionality. The responses closely align to the adult conceptualizations of sense of community as purported by McMillan and Chavis (1986). Implications of this research suggest that children can and should have an integral role in designing a curriculum and systems relevant to the school context if we are at all concerned with their psychological wellness.

Cyanobacterial Blooms in the Wetlands of the Perth region, Taxonomy and Distribution: an overview

J John et al. — Tue, 23 Mar 2010 22:40:29 PDT

The distribution pattern (spatial and temporal) of cyanobacterial blooms in Perth wetlands and the Canning River in Western Australia has been investigated sporadically over a span of 20 years. The major bloom-forming species have been identified as Microcystis aeruginosa, M. flos-aquae, Anabaena circinalis, A. spiroides and Nodularia spumigena. Blooms of potentially toxic Anabaena spp. have occurred in the Canning River since 1993, and in many Perth wetlands for several years. For the first time, the Swan River estuary itself experienced a prolonged toxic bloom of Microcystis flos-aquae in February 2000. The two species of Anabaena and Microcystis aeruginosa blooms have occurred under salinity of less than 3 ppt, whereas blooms of Microcystis flos-aquae occurred in salinity above 3 ppt. Microcystis blooms were most common and persistent in most of the alkaline, shallow, mostly mesotrophic to eutrophic lakes but rarely in oligotrophic lakes. Both species of Microcystis were often found together, although M. flos-aquae appeared to be dominant in late summer and autumn, when salinity levels were at maximum. Shape and size of colonies and cells were the stable morphological features differentiating the two species of Microcystis. Microcystins associated with these blooms ranged from < 0.5 to 1 645 µg L-1 in wetlands and 0.05 to 124 µg L-1 in the Swan River estuary. Nodularia spumigena blooms were confined to two freshwater lakes with salinity slightly below 3 ppt. This is the first time N. spumigena blooms are reported in freshwater lakes. The hepatotoxin nodularin was also detected in these wetlands, but at low levels.

Grasstree (Xanthorrhoea preissii) leaf growth in relation to season and water availability

Dylan Korczynskyj et al. — Tue, 26 Jan 2010 17:12:14 PST

Water stress usually arrests growth of even the most deep-rooted species during summer drought in Mediterranean-type climates. However, scant evidence suggests that grasstrees may represent an unusual exception. We used weather data and plant water potential to investigate the relationship between leaf growth and season in the grasstree, Xanthorrhoea preissii Endl. (Xanthorrhoeaceae). Leaf production in two contrasting habitats revealed continuous annual growth, oscillating between maximum rates (2.5–3.2 leaves/d) in late-spring to autumn, to a minimum rate of 0.5 leaf/d during winter but never stopping. While the rate of leaf production during the fast-growth season was positively correlated with temperature above 17–18°C, leaf elongation commenced substantially earlier in the year (from 12°C). Leaf water potentials cycled annually, with predawn readings commonly measured as zero during winter–spring and as low as −1.26 MPa during summer, but never indicating stress by exceeding the turgor loss point. Leaf death was synchronized with summer drought. The fast (summer) growth period was characterized by rapidly fluctuating leaf production, particularly in banksia woodland, where plant growth reliably responded quickly to >18 mm of rainfall. Within 24 h of 59 mm of simulated rainfall, grasstrees in banksia woodland showed a marked increase in water potential, and leaf production reached 7.5 times the controls, confirming their capacity to respond to temporary spasmodic summer rains. Rainfall was the best climatic variable for predicting woodland grasstree leaf production during summer, whereas leaf production of forest grasstrees was most closely correlated with daylength. This plastic response of grasstrees between seasonal weather extremes is relatively rare among other mediterranean floras, and has implications for a recently proposed technique for ageing grasstrees.

Short-term Water Quality Variability in Two Tropical Estuaries, Central Sumatra

Peta G. Sanderson et al. — Thu, 30 Apr 2009 21:30:18 PDT

We examined high frequency fluctuations in water quality parameters in two tropical coastal plain estuaries in response to changing tidal flow conditions. The variability in total suspended sediments (TSS), volatile suspended solids (VSS), total organic carbon (TOC) concentrations, and indicators of water quality, including pH, temperature, salinity, and dissolved oxygen, over one spring tidal cycle during the early wet monsoon season was measured in two estuaries in eastern Sumatra. The relatively high rainfall experienced throughout the year, in combination with the recent extensive vegetation clearing and modification of the landscape, resulted in significant concentrations of TSS, VSS, and TOC being discharged to coastal waters. Maximum values are reached on the ebb tide (TSS > 1,013 mg 1^-1; VSS > 800 mg 1^-1; TOC > 60 mg1^-1). The influence of freshwater discharge and tidal flow on water properties of the lower estuaries is also marked by the variability in salinity, dissolved oxygen, and pH over the tidal cycle, with minimum values for each of these parameters following maximum current velocities and after the completion of the strong ebb tide. Estimation of seaward sediment fluxes, which are of significant interest in a region where rapid environmental change is occurring, would require further examination of sedimentary processes, such as resuspension and advection of sediment, as well as a consideration of neap-spring tidal variations and the effect of seasonality on estuarine circulation.