In 1985, Dashidaira Dam, equipped with a flushing gate, was built on the Kurobe River in Toyama, Japan. Since the dam sediments were first flushed out in December 1991, benthic fish counts have decreased year by year due to repeated flushing of clay-rich dam sediments.

In June 2001, the flushed dam water contained a low oxygen concentration (1 to 2 mg/l) and high concentrations of smectite and vermiculite. To establish the cause of the death of the benthic fish, living flatfish were collected from Toyama Bay in order to examine their gills, which showed tissue damage and chemical changes caused by adherent expandable clays, derived from the flushed dam sediments. For comparison, exposure experiments on rainbow trout were carried out using smectite suspensions. Examination by optical microscopy revealed that the gills had shrunk because of the smectite concentrations. Low oxygen concentrations and large amounts of expanding clays have a significant effect on downstream benthic life.

The dam reservoirs of the Upper Rhone were drained every three years until 2003, and the water level of the Villebois reservoir was lowered by 1.5 m. This resulted in considerable drying of its littoral habitats and the disappearance of the abundant macro-invertebrates that live in them. This study investigates the response to this drying disturbance of bivalve populations and especially of the life history traits of the two potamic species, Pisidium moitessierianum and Pisidium supinum. The low density of these bivalves observed during the months following the drying of May 2003 until spring 2004 shows that the contribution of drift in population recovery was very limited during this period. Due to the faster turnover of its cohorts and a higher increase in litter size in 2004, P. moitessierianum once again dominated bivalve communities from 2005 onwards. In the Villebois reservoir recovery of bivalve communities in terms of structure and density was total three years after the drying of 2003. Observations suggest an increase in litter size and continuous recruitment: the reproductive strategy adopted by these bivalves represent response to the fall in numbers on the one hand, and to considerable magnitudes of temperature and flow rates on the other hand, enabling the rapid adjustment of populations to drying disturbance and variations in environmental conditions. Taking into account the response of bivalve populations to this event, its effects are comparable to those of a supra-seasonal drought (Lake, 2003, Freshw. Biol., 48, 1161–1172).

Tropical rain forests are evergreen and experience a climate suitable for plant growth year round (Whitmore 1998). However, most tropical rain-forest trees display periodic shoot growth (Borchert 1991) and show synchronous leaf flushing at the community level (Itioka & Yamauti in press, Medway 1972, Ng 1981). Synchronous leaf flushing may have a great impact on animal population such as herbivores, because young leaves are suitable food resources for many herbivores (Aide 1988, 1992; Coley 1983, Itioka & Yamauti 2004, Lowman 1985).

Energy metabolism during flushing of mink (Mustela vison) in relation to a control group was studied by means of combining pooled data from balance and respiration experiments carried out in 1993 (experiment I) and 1994 (experiment II) and some blood metabolites from experiment II. The experiments, which were divided into six 1-week balance periods, started on 7 February and continued until 22 March. Flushing was performed by restricted feeding in periods 2 and 3 and refeeding in periods 4 and 5. Each balance period included a 24-h measurement of heat production by means of indirect calorimetry in open-air circuit respiration chambers. In experiment II blood samples were taken at weekly intervals and analysed for total triiodothyronine, total thyroxine, free thyroxine, glucose, insulin and fructosamine. Generally, intake of digestible nutrients and energy metabolism measurements within the flushed group were strongly influenced by period (energy supply), whereas they remained stable in the control group and differences between treatment groups over the total experiment were non-significant. The fluctuation in energy status induced by flushing did not involve major changes in body weight. Blood metabolites reflected the food intake by being fairly stable in the control group and decreasing during restriction and increasing during refeeding in the flushed group (P < 0·05). As an effect of flushing the number of corpora lutea increased significantly (P < 0·05).