Sediment samples from the coastal lagoons and estuaries of New York and New Jersey were used to investigate the influence of contaminants on diatom assemblages. Multivariate analyses demonstrated correspondence between composition of diatom assemblages and concentrations of several metals and total PAH. The effects of the individual contaminants were difficult to disentangle because of the considerable correlations between their concentrations. The most conspicuous trend was the increase in the relative abundance of small centric planktonic diatoms in response to contamination and the corresponding decrease in the benthic flora. The high relative abundance of planktonic species on contaminated sediments apparently resulted not so much from their tolerance to pollution, but from the paucity of benthic species. A comparison of the assemblages on the surface and at the depth of approximately 8-10cm revealed a statistically significant temporal change in community composition towards planktonic diatoms.
This tutorial demostrates the use of ordination methods in R package vegan. The tutorial assumes familiarity both with R and with community ordination. Package vegan supports all basic ordination methods, including non-metric multidimensional scaling. The constrained ordination methods include constrained analysis of proximities, redundancy analysis and constrained correspondence analysis. Package vegan also has support functions for fitting environmental variables and for ordination graphics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.