Self-filling enclosures to experimentally assess plankton response to pulse nutrient enrichments.

Experimental nutrient additions are a fundamental approach to investigating plankton ecology. Possibilities range from whole-lake fertilization to flask assays encompassing a trade-off between closeness to the "real world" and feasibility and replication. Here we describe an enclosure type that minimizes the manipulation of planktonic communities during the enclosure filling.

Weed cutting in a large river reduces ecosystem metabolic rates in the case of River Gudenå (Denmark).

Problems related to extensive macrophyte growth are widespread both in modified and man-made canals and streams, and in streams with natural morphology and rich vegetation. The weed cutting is a common management practice in order to reduce flood risk and enhance water conveyance. Although the short- and long-term impacts on the stream physical habitats and biota have been extensively studied, only little information exists on the effects of weed cutting on ecosystem metabolism, especially for larger rivers.