Ecological Indicators (Oct 2023)
Unveiling the influence of specialists and generalists on Macroinvertebrate assemblage heterogeneity in lake Taihu
Abstract
The loss of biodiversity in the era of fast environmental change is often revealed as biotic homogenization. In the large and nutrient-rich Lake Taihu located in eastern China, we evaluated the degree of specialization among organisms and the impact of environmental factors on macroinvertebrate assemblages. First, we measured the niche widths of macroinvertebrate species in respect to environmental conditions and utilized the Outlying Mean Index (OMI) analysis to categorize them into specialists and generalists. The effects of environmental factors on assemblages of macroinvertebrate taxa identified by varying niche widths were then investigated using the lake dataset. Within our study lake, habitats display considerable environmental gradients, resulting in habitat heterogeneity linked to several habitats, and have no barriers to species migration. Generalist macroinvertebrate taxa dominated the macroinvertebrate assemblages in our study lake, but some differences were evident among the different habitat types of the lake. The macrophyte-dominated habitat (MDH) displayed the highest species richness for both generalists (11 species) and specialists (8 species), while the algal-dominated habitat (ADH) had lower richness but higher overall abundances. Generalist species showed the largest abundances, exhibiting considerable spatial heterogeneity among the sampled sites. Our results showed that generalists shape macroinvertebrate assemblages through their abundance and richness variation in large shallow lakes. Furthermore, strong environmental gradients and a high degree of habitat connectivity within large lakes allow specialist and intermediate species to maintain high richness in resource-rich habitats, in addition to generalist species also maintaining high abundance in such lakes.
