Studies on the Physiology of Hyacinth Bulbs Hyacinthus Orientalis L. I. Sugar Content and Metabolic Activities in Bulbs Exposed to Low Temperatures

Changes in the content of carbohydrates and in the activity of hydrolytic enzymes were studied in hyacinth bulbs exposed to low temperatures. It was found that the amount of insoluble carbohydrate initially present in the scales and buds of hyacinth bulbs decreased greatly after a prolonged period of low temperature treatment. This decrease was greater in rooted bulbs, held at a low temperature for 63 days in natural conditions, than in unrooted bulbs stored in a refrigerator for the same period. At the same time the levels of soluble mono- and oligosaccharides, and of soluble starch, increased in the scales and buds of chilled bulbs. These changes in sugar level were found to be correlated with changes in the activity of certain hydrolytic enzymes. The activity of these enzymes was higher in rooted bulbs than in those which had not rooted before treatment. The activity of hydrolytic enzymes was found to be considerably higher in the flower buds than in the scales.     

Sensitivity of alpine stream ecosystems to climate change and human impacts

• 1 Climatic changes and water resource developments alter the relative contribution of the water sources (glacier-melt, snow-melt, rainfall run-off and springflow) to the discharge regime of alpine streams.
• 2 Likely changes in the magnitude and variability of a range of climatic determinants of glacier behaviour, as a result of an enhanced Greenhouse Effect, are shown to have important implications for the future hydrogeomorphological and thermal dynamics of alpine streams.
• 3 Zoobenthic communities typically show deterministic patterns in alpine streams due to the over-riding influence of water temperature and channel stability. These communities could act as indicators of change in the relative contribution of run-off, particularly to alterations of glacier-melt patterns.
• 4 A reduction of glacial meltwater, following diversion for HEP generation, is used as an example to illustrate the sensitivity of the zoobenthic communities to changes in temperature and flow regimes, and geomorphological dynamics.

     

Damselfish as keystone species in reverse: intermediate disturbance and diversity of reef algae

Substrates located within the defended territories of Hawaiian damselfish for 1 year were subjected to intermediate grazing intensity and, as a result, showed greater diversity of algae than substrates either protected within fish-exclusion cages or exposed to intense fish grazing outside territories. Thus, this damselfish enhances local diversity on reefs through "intermediate-disturbance" effects, and is a keystone species that decreases rather than increases overall predation intensity relative to areas where it is absent.