Principal component analysis (PCA) is one of the most commonly used tools in ecological data. This method reduces effective dimensionality a multivariate data set by producing linear combinations original variables (i.e., components) that summarize predominant patterns In order to provide meaningful interpretations for principal components, it important determine which are associated with particular components. Some analysts incorrectly test statistical significance correlation between and...

Data on the presence or absence of 25 fish species in a survey 52 lakes from watersheds Black and Hollow rivers south-central Ontario were analyzed with eight similarity coefficients. Comparisons made Jaccard, Ochiai, Phi, Rogers-Tanimoto, Russell Rao, Simple Matching, Sorensen-Dice, Yule coefficients using results R-mode cluster analysis, principal-coordinates analysis (PCoA), nonmetric multidimensional scaling. Coefficients grouped into those representing measures co-occurrence measuring...

A method is presented that constrains principal components analysis (PCA) to extract a first component that, by definition, summarizes isometric size alone. The remaining information partitioned according variation in shape. Size-constrained and conventional procedures are compared with analyses of data on sexual dimorphism the painted turtle (Chrysemys picta marginata) crayfish (Cambarus bartoni). Contrary results from standard using covariance or correlation matrices, size-constrained...

En comparant les changements survenus a long terme dans communautes de crustaces zooplanctoniques trois lacs experimentalement chaules situes pres des usines metallurgiques Sudbury (Ontario) avec valeurs temporelles et spatiales mesurees reference distance Sudbury, nous (i) demontrons l'utilite l'etude la restauration d'un bassin lacustre, (ii) comparons indicateurs univaries multivaires (iii) determinons si rapidite depend gravite pollution acide metallique. Les ont permis d'etablir...

Matrix comparison tests (i.e., Mantel's test or quadratic assignment) are employed with increasing frequency to measure the concordance between genetic, behavioural, morphological, ecological, and geographic distances. Such compare an observed of matrix association a null distribution derived from randomly generated subset all possible permutations one original matrices. Typically, 500–2000 permutated matrices used generate statistical thereby estimate probability obtaining two We...

Studies of ecological communities often make implicit assumptions that the species have nonrandom patterns organized through biotic and abiotic factors. Although such are generally not tested, analyses conclusions derived depend on patterns' being present. Several "null" or "neutral" models been proposed to test for these patterns. We contrast two more prevalent develop new models, subsequently evaluating them with five sets fish community data. Three null provide similar results, from which...

Time trends in abundance, body size, species richness, and composition indicate that crustacean zooplankton communities of southern Canadian Shield lakes changed between 1980 2003. Total abundance did not decline despite reductions total phosphorus, but all other metrics changed. Species richness declined Harp Lake (Ontario, Canada) following its Bythotrephes invasion, increased three lakes. Average cladoceran length from 0.6 to 1.0 mm seven the lakes, as larger-bodied taxa replaced smaller...

We analyzed the 21‐yr dynamics of dissolved organic carbon (DOC) in 55 lakes during ice‐free periods five regions across eastern Canada relation to total solar radiation (TSR), precipitation, air temperature, sulfate deposition (SO4), Southern Oscillation Index (SOI), North Atlantic Oscillation, and Pacific Decadal (PDO). A synchronous pattern DOC was found among within each region; however, a not regions, except for Kejimkujik Yarmouth. Long‐term trends increasing or decreasing...

Abstract The ball‐and‐cup diagram for conceptualizing ecosystem stability, resistance, and resilience is often presented as a ball rolling around within between two or more cups. This analogy has long history in ecology been used to illustrate changes over time where the magnitude of required push from one cup another represents regime shift an alternative state. Another approach visualizing involves ordinations repeated measures community data environmental variables tracking trajectories...

We investigated the temporal coherence (i.e., correlation or synchrony between time series) of annual abundances among populations freshwater zooplankton in eight lakes Ontario, Canada, from 1980 to 1992. estimated using intraclass coefficient (ri). While values ri were relatively low comparisons all lakes, they statistically significant for three seven common cladoceran and copepod taxa (Bosmina longirostris, Leptodiaptomus minutus, Mesocyclops edax). These positive correlations imply that...

Abstract. Both lake-specific (e.g. pH) and regional precipitation) factors affect DOC concentration pattern. Using annual in nine boreal lakes the ice-free season, potential influences of five factors, air temperature, precipitation, SO4 deposition, solar radiation (photosynthetically active radiation, or PAR) southern oscillation index (SOI) have been explored through multiple regression. Mean winter precipitation summer explained 59% variation mean (F3,17= 8.29, p= 0.0013). Solar were...

We used multiple linear regression analyses to explore empirical relationships between dissolved organic carbon (DOC) concentrations, weather, and acidification in long-term data sets from 12 small Boreal Shield lakes Ontario, Canada. In two which pH changes have been very large (4.5 ~6.0), explained most of the temporal variation DOC concentrations. remaining lakes, average previous temperature (on scale a decade or more) was usually best explanatory variable for Lake-specific models...

Large reductions in sulphur emissions at the Sudbury, Ont., Canada, smelters recent decades have resulted decreased lake acidity, and biological improvements followed. Lakes Sudbury area offer a very unique opportunity to develop our understanding of processes regulating restructuring aquatic ecosystems recovering from acidification. Here, we examine changes crustacean zooplankton communities that accompanied chemical recovery Whitepine Sans Chambre lakes, near over last two decades. In both...

Morphological variation in size and shape has physiological, ecological taxonomic significance (e.g., Peters, 1983; Schmidt-Nielsen, 1984; Bookstein et al., 1985). As a result, there is considerable interest partitioning components of associated with from Mosimann James, 1979; Humphries 1981; Reist, 1985; Sampson Siegel, Somers, 1986; Corruccini, 1987). Size-related often evaluated within bivariate framework involving logarithmic transformations regression Smith, 1980; Seim Saether, 1983)....

Researchers in aquatic sciences frequently employ empirically derived models to predict productivity, yield, and abundance of fish. We demonstrate that predictive employing ratios standardized biomass lake morphometric variables are biased by spurious correlations due mathematical transformations the use inappropriate null models. Our findings emphasise studies incorporating like mean depth or morphoedaphic index require cautious interpretation. Future research should focus on more...

Based on chemical criteria such as excess sulfate and low bicarbonate relative to cation, 50 lakes in the Wawa area show some degree of acidification. We conclude that observed perturbations lake chemistry fish populations were primarily result smelting operations area. Six have acidified pH 3.1–4.1 had high concentrations metals Al, Mn, Fe. Most contact with felsic mafic metavolcanic rocks containing minerals siderite, only a few granitic basins. The six most acidic contained no fishes...

The role that climate plays in determining the temporal dynamics of freshwater zooplankton is poorly understood, despite its potential to synchronize population on a regional basis. We quantify spatial synchrony common taxa among lakes Dorset, Ontario, area and investigate climatic mechanisms responsible for these patterns at both annual seasonal scales. show several are characterized by similar abundance across region, suggesting synchronising effect abundances. Using multiple regression...

We examined long-term changes in phytoplankton composition from 1981 to 2003 seven intensively studied lakes on the southern Canadian Shield Ontario, Canada. Significant (P < 0.05), temporally coherent increases relative biovolume of colonial chrysophytes were observed six lakes, with coincident declines diatom algae. Variance partitioning analyses identified water chemistry variables, and co-variation physicoclimatic as most important structuring assemblages through time study (variance...