Impaired short-term functioning of a benthic community from a deep Norwegian Fjord following deposition of mine tailings and sediments

The extraction of minerals from land-based mines necessitates the disposal of large amounts of mine tailings. Dumping and storage of tailings into the marine environment, such as fjords, is currently being performed without knowing the potential ecological consequences. This study investigated the effect of short-term exposure to different deposition depths of inert iron ore tailings (0.1, 0.5, and 3 cm) and dead subsurface sediment (0.5 and 3 cm) on a deep water (200 m) fjord benthic assemblage in a microcosm experiment. Biotic and abiotic variables were measured to determine structural and functional changes of the benthic community following an 11 and 16 day exposure with tailings and dead sediment, respectively. Structural changes of macrofauna, meiofauna, and bacteria were measured in terms of biomass, density, community composition and mortality while measures of oxygen penetration depth, sediment community oxygen consumption and 13C-uptake and processing by biota revealed changes in the functioning of the system. Burial with mine tailings and natural sediments modified the structure and functioning of the benthic community albeit in a different way. Mine tailings deposition of 0.1 cm and more resulted in a reduced capacity of the benthic community to remineralize fresh 13C-labeled algal material, as evidenced by the reduced sediment community oxygen consumption and uptake rates in all biological compartments. At 3 cm of tailings deposition, it was evident that nematode mortality was higher inside the tailings layer, likely caused by reduced food availability. In contrast, dead sediment addition led to an increase in oxygen consumption and bacterial carbon uptake comparable to control conditions, thereby leaving deeper sediment layers anoxic and in turn causing nematode mortality at 3 cm deposition. This study clearly shows that even small levels (0.1 cm) of instantaneous burial by mine tailings may significantly reduce benthic ecosystem functioning on the short term. Furthermore, it reveals the importance of substrate characteristics and origin when studying the effects of substrate addition on marine benthic fauna. Our findings should alert decision makers when considering approval of new deep-sea tailings placement sites as this technique will have major negative impacts on benthic ecosystem functioning over large areas

Chronology of wing development in Megoura viciae Buckt. and Acyrthosiphon pisum Harris (Homopera: Aphididae)

The development of wings was studied in males of Megoura viciae and winged parthenogenetic females od A. pisum. Wing buds are evident two days before birth in both males and females. No wing bud-like structures were observed in wingless females both before and after birth

DNA content in the nurse cell nuclei of viviparous and oviparous females of Megoura viciae

Microfluorometric evaluations of DNA content carried out in both viviparous and oviparous females of Megoura viciae have shown that the increased nuclear volume of the nurse cell nuclei is due to repeated duplications of the whole genome. DNA overreplication begins, together with the first appearance of the ommatidia, 3 days before birth both in viviparous and oviparous female embryos, but it proceeds at different rates in the different reproductive categories. In oviparous females, 11 replication cycles take place (maximum DNA content 2048C), whereas in viviparous females only a few DNA replications occur (maximum DNA content 16C). The relationship we found between the increased DNA content in nurse cell nuclei and development of ommatidia suggests that the switch mechanism determining the beginning of DNA overreplication may be directly influenced by photoperiod effects on the developing embryos

INTERAZIONI TRA FUNGHI E AFIDI NELLA INDIVIDUAZIONE DI STRATEGIE DI LOTTA BIOLOGICA.

E' stato effettuato uno studio sulle interazioni tra il fungo Trichoderma harzianum e l'afide Schizaphis graminum, uno dei più importanti agenti nocivi delle colture cerealicole. Lo studio ha messo in evidenza una diversa sensibilità delle forme attere e alate: infatti il fungo aderisce e si sviluppa sulle forme alate, mentre non aderisce e non ha nessun effetto sulle forme attere

Characterization of Acyrthosiphon pisum Harris (Homoptera, Aphididae) karyotype using G and C banding.

The paper deals with the characterization of Acyrthosiphon pisum Harris (Homoptera, Aphididae) karyotype using G and C banding

Effetto repellente di isolati fungini su due specie di afidi.

L'effetto repellente di isolati fungini del genereTrichoderma è stato studiato su due specie di afidi: Schizaphis graminum, Megoura viciae

New approaches to the study of aphids chromosomes.

The paper describes the advantages in using new approaches to the study of aphids holocentric chromosomes