Which Are Harder? Soft Skills or Hard Skills?

Contains fulltext : 161352.pdf (preprint version ) (Open Access

Cultural Credit for Collaborative Contributions to Support Interdisciplinary Ecology

<p>Presentation for the 2013 NSF Macrosystems Principle Investigator's meeting in Washington DC.</p

Temporal and spatial variation of limnological variables and biomass of different macrophyte species in a Neotropical reservoir (São Paulo - Brazil)

AIM: This study reports an investigation of limnological characteristics and aquatic macrophyte occurrence in a neotropical reservoir in order to assess the spatio-temporal variation of water and sediment variables and their influence on plant distribution. METHODS: Macrophytes, water and sediment samples were collected from a Brazilian reservoir in different seasons from four main arms of the reservoir. In total sixteen water-sediment variables were analyzed including N:P ratio and Trophic State Index. The plants were collected using a quadrat sampling procedure and the dry weight per sample was measured. MANOVA was performed to evaluate spatial and temporal variation of environmental variables as well as seasonal biomass differences. To assess the relationship among environmental variables and macrophytes an ordination analysis (using Canonical Correspondence Analysis: CCA) was carried out. RESULTS: The spatial and temporal variation of limnological variables generated a heterogeneous system which supports the presence of different species of macrophyte. pH, dissolved oxygen and sediment composition were important predictors of Polygonum lapathifolium occurrence while nutrients were associated with Eichhornia crassipes and Pistia stratiotes. Inorganic substances were related to biomass variation of Eichhornia azurea and Myriophyllum aquaticum. CONCLUSIONS: The spatial variation of the environmental variables has caused heterogeneity in the reservoir and it may support the occurrence of different species of macrophyte. Limnological variables highlighted in CCA are important to predict the species occurrence and their control in the study area

Macrophyte architecture affects the abundance and diversity of littoral microfauna

We tested the hypothesis that structural complexity is an important factor influencing the abundance and taxon richness of microfauna (e.g., rotifers, copepods, cladocerans) in littoral habitats. Research on littoral microfauna has to date focused mainly on field observations, which commonly show microfauna have preference for some macrophytes over others. However, while such studies commonly conclude that macrophyte architecture is a major determinant of these variations, independent factors may also be responsible (e.g., differences in macrophyte ages, differences in macrophyte bed densities and the depth of the respective macrophyte beds sampled). We used artificial macrophytes with three levels of complexity to keep the surface area and mass of the substrate sampled constant, and to control for confounding factors not related to the complexity of the plants. Our results support the hypothesis that structural complexity is an important factor influencing abundance and taxon richness, independent of other potential confounding factors. Microfaunal (mainly rotifer) abundance and richness were generally greater on more complex artificial macrophytes, likely a result of more complex substrates (1) providing a greater variety of habitat, (2) supporting a greater concentration or variety of food and/or (3) affording greater protection against predators. Less mobile surface-associated (i.e., benthic/periphytic) taxa were found to discriminate among substrates, whereas the abundance and richness of planktonic species were not affected by complexity level. Relatively low abundances and taxon richness of microfauna recorded in control samples, which did not contain artificial macrophytes, supports the contention that vegetated areas sustain a higher abundance and variety of species than non-vegetated areas