Development of hormosira banksii (PHAEOPHYCEAE) embryos in selected components of secondarily-treated sewage effluent

We investigated the effects of phosphate, ammonium, and a mixture of heavy metals as components of sewage effluent, together with the effects of reduced salinity due to sewage effluent discharge into a marine environment, on the development of Hormosira banksii (Turner) Decaisne embryos. The concentration of each effluent component tested in this study was calculated to approximate levels in the shore zone where H. banksii once occurred at Boags Rocks (Victoria, Australia) and the artificial sea medium was diluted to 20‰ S based on average salinity levels measured at this site. Newly fertilized eggs were cultured in each of these components and combinations of components for up to 7 days. Ammonium, elevated to levels that occur in the vicinity of the outfall, and fresh water, which reduces seawater salinity, were the most damaging of the effluent components tested. Osmotically stressed embryos commonly showed swollen chloroplasts, loss of cell contents, vesiculate cytoplasm, and stunted rhizoid development. Exposure to elevated levels of ammonium retarded embryo development and growth until day 7, when cellular damage became evident. The number of damaged embryos was significantly greater when exposed to elevated levels of ammonium added to artificial seawater medium diluted to 20‰ S. The adverse effects caused by elevated levels of ammonium and reduced seawater salinity on H. banksii embryo development could have contributed to the disappearance of this species from Boags Rocks.     

Interaction between humic substances and carbohydrates in a Pampasic pond (Argentina)

Interaction between humic substances from a Pampasic pond and carbohydrates was studied. Determinations were performed by gel chromatography using radiolabeled glucose. The results showed that upon lowering the pH the interaction decreases in relation to the steric arrangement that causes the diminution of the accessibility of the available sites. Results of displacement experiments carried out by addition of unlabeled glucose, galactose, saccharose and starch, confirmed that the interaction occurs mainly through labile non specific bonds and is, to a certain degree, independent of the carbohydrate molecular weight involved. This revised version was published online in July 2006 with corrections to the Cover Date.     

Terrestrial Chironomidae on agricultural soil treated with sewage sludge

Adult Chironomidae were caught in emergence traps for three subsequent years (1988–1990) on agricultural soil. Larvae were extracted from soil samples taken since June 1989. The field was subdivided into 5 plots treated with different amounts of sewage sludge. On some plots the sludge was artificially enriched with heavy metalts. The phenology of Chrinonomidae in the three years and their distribution over the different plots are discussed. The results suggest that the abundance of Chironomidae is increased by sewage sludge and appears to be also increased by heavy metals.