Relationship between plant roots and benthic animals in three sediment types of a dimictic mesotrophic lake
Relationships between plant roots and benthic animals were studied in a mesotrophic, dimictic lake. Two field studies were investigated, the first focusing on differences in benthic community parameters inside and outside a root zone under selective sampling on three sites; the second tested the same differences but under random sampling in three 9m2 plots. All the data were also analyzed against three sediment types. A positive relationship was discovered between presence of plants and numbers of certain chironomid groups (brown and non-predatory chironomids, chironomid genera and total number of animals) on silty sediment. Also, presence of roots influenced abundance of oligochaetes but with no specific relationship to sediments. Abundances of red chironomids and amphipods were related to sediment type when analyzed outside the root zone. Study design (selective or random sampling within an area) influenced results for all the animal groups but especially for predatory chironomids (Tanypodinae). In general, brown and red hironomids followed different patterns, and distribution patterns of brown chironomid-related groups were similar to ones expected from the influence by oxygen released from plant roots. Calculations suggest that the oxygen released from roots could support about 25 chironomids in vicinity of one plant. These results suggest that brown chironomid-related animal groups might be aggregated around plant roots because of higher oxygen concentrations.