Microhabitat–zooplankton relationship in extensive macrophyte vegetations of eutrophic clear-water ponds

Abstract

The influence of different macrophyte taxa or growth forms on biological and environmental variables is often analysed in one-lake studies. However, the unique combination of non-vegetational characteristics of a waterbody, i.e. its site identity, can be an influential factor in itself, shaping the measured parameters irrespective of the presence or absence of certain macrophyte species. In this situation, the relative strengths of all factors can be determined best in a study that explicitly accounts for differences in the identity of the waterbodies. Several functional macrophyte groups are known to provide a potent microinvertebrate refuge or permanent habitat. The objective of this study was to detect patterns in the zooplankton assemblages associated with different extensive habitats of macrophyte species and to relate these patterns to three major factors: the microhabitat, the pond identity and the seasonality in the warmer months of the year. Five ponds located in the Woluwe catchment of the Brussels-Capital Region (Belgium) were studied monthly for macrophyte and zooplankton characteristics from July until October 2005. The vegetation in the clear ponds was characterized by extensive monospecific stands (Ceratophyllum, Chara, Nitella, Potamogeton, Nuphar and filamentous algae). Zooplankton could be analysed in seven different vegetation types and in the open water zones and contained a total of 17 cladoceran and 27 rotifer genera. Principal components analysis (PCA) ordination of zooplankton communities showed a seasonal gradient and a tendency to group within-pond habitats, although they differed in macrophyte species and habitat structure. Despite the absence of clustering of similar microhabitats across ponds, percent volume infested (PVI), vegetation biomass density and Daphnia length (used as a proxy for fish predation pressure) contributed significantly positive to the Shannon zooplankton biodiversity indices. Moreover, densities of most zooplankton subgroups and of total zooplankton were significantly and positively related to PVI. It is assumed that in eutrophic ponds, extensive, often monospecific macrophyte vegetations provide an ecological environment suitable for both macrophyte-associated species and migrating pelagic zooplankton, thereby maintaining a high microinvertebrate biodiversity.

Water quality and communities associated with macrophytes in a shallow water-supply reservoir on an aquaculture farm

“…These results can mostly be explained by macrophytes habitat and morphology present in this shallow reservoir, which both macrophytes are floating perennial aquatic plant or free-floating perennial or annual macrophytes. The number of planktonic taxa found was higher than those pointed by Albertoni et al (2007) and lower than found by Onsem et al (2010).…”

“…Macrophyte stands may also be responsible for the existence or the amplification and compression of vertical gradients in physical-chemical parameters such as light and oxygen availability. This may increase the faunal diversity over the whole water column (Onsem et al, 2010).…”

“…Submerged macrophytes are considered most suited as a daytime refuge, although some studies indicate the occurrence of a protective potential offered by stands of floating leaves and emergent vegetation with shelter to the zooplankton community (Onsem et al, 2010).…”

Zooplankton diversity and macrophyte biometry in shallow water bodies of various trophic state

“…The wide range of the zooplankton diversity index in the investigated ponds reflected a high level of habitat heterogeneity. Macrophytes in ponds, which can overgrow the whole column of water or occur in patches, can be a home for a variety of zooplankters, both macrophyte-associated as well as migrating pelagic species, as stated by van Onsem et al (2010). Thus, a great range of zooplankton diversity was also ascertained for small water bodies in an agricultural landscape.…”

Macrophyte - environment relationships during a monospecific and a multispecific massive invasion in a fishpond

“…They affect the habitat of the plankton community, particularly as a food source directly or indirectly through the periphyton growing on the macrophytes. Macrophyte species have specific and divergent traits that result from details in plant architecture, allelopathic activity, palatability for herbivores and association with certain organisms that may attract or repel zooplankton species (Van Onsem et al 2010). The micro-invertebrate community associated to macrophytes consists of planktonic, phytophylus and micro-faunal species (Zrum & Hann 1997).…”