Identifying sub-habitats in ponds

Posted on December 28, 2013

While substrate particle size is the most influential factor affecting the distribution of macroinvertebrate species in freshwater streams, in stillwater lakes and ponds aquatic vegetation is much more important. Aquatic macrophytes play key ecological roles by providing surfaces for periphyton, macroinvertebrates and developing eggs, and by sheltering animals from attacks by larger predators. The possibility that different macrophyte species act as distinct sub-habitats for separate invertebrate communities was investigated in a study of a single pond in northwest England. The pond had a surface area of 700 m2, a maximum depth of 140 cm and a clay bottom overlain with coarse gravel and fine silt. It was well supplied with nutrients and supported five species of aquatic plants. Vegetated, open-water and pond bottom sub-habitats were sampled for macroinvertebrates by making 1 m sweeps with a 900 µm mesh pond net. Multivariate pattern analyses showed that the various sub-habitats supported different invertebrate communities that could be distinguished by their positions on two environmental gradients, namely the transition from open water to dense vegetation, and the degree of three-dimensional complexity of the vegetation. Four main types of sub-habitat were recognised: (1). Submerged plants with dense, complex leaf structure (Ceratophyllum, Elodea, Callitriche); (2) Emergent and floating-leaf plants with simple structure (Phragmites, Nymphaea); (3) Bottom substrate; and (4) Open water. Mean invertebrate abundance varied significantly between habitats, being relatively high in vegetation and over four times greater in complex than in simple plant habitats. Lowest numbers of invertebrate individuals and species were recorded in open water. The study illustrates how the structural diversity of aquatic vegetation can have a strong influence on the makeup of invertebrate communities in small bodies of water.

Reference: Walker, P., Wijnhoven, S. & Van der Velde, G. 2013. Macrophyte presence and growth form influence macroinvertebrate community structure
Aquatic Botany 104, 80–87.