The first biomanipulation conference: a synthesis

Abstract

At the First Biomanipulation Conference held in Amsterdam (8-11 August 1989), studies presented considered mainly trophic interactions in lakes, enclosures and laboratory systems. Studies on the interactions between phytoplankton and zooplankton emphasized the edibility of the phytoplankton in relation to the zooplankton size structure and the trophic state. Most lake experiments involved 50-100 reduction in fish standing stock or alternatively heavy stocking with piscivorous fish. The most dramatic effects of biomanipulation were found in shallow, eutrophic lakes which exhibited radical changes in ecosystem structure because of changes in light climate and consequently, luxuriant development of macrophytes. There was still much controversy about the top-down effects in relation to trophic state, especially those concerning the role of fish and zooplankton in the development and succession of phytoplankton. Many experiments showed indirect effects within the food web, emphasizing the importance of feedbacks and the complexity of the food web rather than the simplicity of the food chain. The stabilizing effects of refugia for zooplankton and fish on the ecosystem were stressed. Shallow lakes responded generally more rapidly to biomanipulation and this was most successfully accomplished when TP concentration was < 50/~g 1-', even though in a few cases at 10-20 fold higher TP concentrations (mostly PO4-P lakes) the results achieved could be maintained for two or more summers. For a guaranteed success of the measures an almost complete removal of fish appeared to be indispensible; moreover in many cases removal of benthivorous fish appeared to be even more important than that of planktivorous fish.

Trophic cascade and biomanipulation: Interface of research and management‐A reply to the comment by DeMelo et al

“…The same factors that demand a lakewide scale in trophic cascade experiments pertain to biomanipulation (Carpenter and Kitchell 1988;Kitchell 1992). Spatial heterogeneity, littoral-pelagic exchange, vertical migrations, and refuges are now seen as critical topics in biomanipulation research (Shapiro 1990;Lammens et al 1990). Although lab or enclosure experiments will remain important for tests of key mechanisms (Frost et al 1988), it is difficult to see how the most crucial questions about biomanipulation can be resolved without whole-lake trials (Shapiro 1990; Lammens et al 1990;McQueen 1990).…”

Interactions between coot (Fulica atra) and submerged macrophytes: the role of birds in the restoration process

“…Further, the simple reduction of nutrient loading has rarely been successful as a single measure (Sas, 1989). It is widely accepted that restructuring the biological community of shallow lakes, usually through biomanipulation of the fish community (Lammens et al, 1990) is important in counteracting buffering mechanisms tending to preserve algal domination even where the nutrient concentration is suitable for stable macrophyte populations (Irvine et al, 1989;Scheffer et al, 1993).…”

Zoo-heleoplankton structure in three artificial ponds of North-eastern Argentina

“…In the three artificial ponds, the variation in densities suggested different patterns of zooplankton abundance associated with trophic and abiotic condition, and with planktivorous fish predation (Lammens et al 1990, Sendacz et al 2006. The composition and seasonal variation were related to the increase of dominant species.…”

“…The dominance of small-sized zooplankters in the three ponds studied here was due to the selective planktivorus fish predation (Gulati 1990), and to the influence of abiotic condition, which can determine the replacement of large-bodied zooplankton by small-sized zooplankton (Lammens et al 1990). …”