Differential influence of a monotypic and diverse native aquatic plant bed on a macroinvertebrate assemblage; an experimental implication of exotic plant induced habitat

Abstract

Aquatic plants mediate ecological processes in aquatic habitats, specifically predator-prey (bluegill sunfish (Lepomis macrochirus Rafinesque)-macroinvertebrate) interactions. Macroinvertebrate colonization is directly and indirectly influenced by substrate heterogeneity, interstitial space, and surface complexity. Exotic invasive plant species, such as Hydrilla verticillata L.F. Royle, may alter the available structure in aquatic habitat by creating a shift to a homogeneous habitat, thus affecting the macroinvertebrate community. Since macroinvertebrates provide a food base for young phytophilic fishes, changes in their density and abundance may alter food webs. We investigated the hypothesis that macroinvertebrate community structure is influenced by differences in habitat heterogeneity by measuring difference between a heterogeneous native aquatic plant bed, homogenous hydrilla plant bed, and habitat with no plants. Studies were conducted in the field (pond) and the experimental treatments were: (1) no plants, (2) monotypic bed of hydrilla, and (3) diverse native plants. Aquatic plants, regardless of species, supported greater macroinvertebrate abundance, richness, and biomass. Macroinvertebrate abundance, richness, and biomass in a hydrilla-dominated habitat did not differ significantly from a diverse plant habitat, except for richness in October. Indicator taxa did differ significantly between respective treatments, suggesting a change in species composition. However, no significant effect of fish predation on macroinvertebrate populations and/or community structure was documented. The data suggest that a shift from a natural mosaic of vegetated habitat to a highly complex monotypic habitat (e.g., exotic hydrilla) may reduce spatial heterogeneity important to structuring a macroinvertebrate assemblage.

Methods for sampling benthic macroinvertebrates in tropical lentic systems

“…Greater macroinvertebrate diversity, richness and abundance might be expected at the vegetated site, given the presence of emergent plants which should have increased habitat heterogeneity, thus providing a greater variety of shelter and food resources (Spänhoff & Arle 2007, Theel et al 2008. In Lower Peirce, the weed-cutting regime reduced the inlake vegetation, leaving a relatively uniform silt/sand benthos with occasional woody debris.…”

Forecasting the impact of an invasive macrophyte species in the littoral zone through aquatic insect species composition

“…Hydrilla verticillata (L. f.) Royle, Hydrocharitaceae) (Theel et al, 2008) the invasion of white ginger lily shifted aquatic insect assemblage composition probably due to habitat alterations. Our results showed that white ginger lily shifted aquatic insect assemblages when compared with other native vegetation bank profiles.…”

Influene of aquatic macrophytes on the interactions among aquatic organisms in shallow wetlands (Upo Wetland, South Korea)

“…Pelagic-and epiphytic algae exhibited different seasonal distribution patterns, suggesting that they showed opposing relationship with the seasonal gradient of macrophyte cover. In general, epiphytic algae were strongly influenced on the seasonal development of macrophyte species due to qualitative and quantitative change of substrate surface of stem or root in accordance with season (Castro et al 2007, Theel et al 2008. The colonization by various macrophytes species increases the substrate surface for attachment of epiphytic algae, thus the macrophytes' dominance can support high abundance of epiphytic algae.…”