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Nicholls K.H.,S 15 Concession 1
Journal of the Marine Biological Association of the United Kingdom | Year: 2013

Six new marine species of the silica-scaled heterotrophic genus Thaumatomastix are formally described: two were found in Canadian Atlantic Ocean coastal waters (T. asymmetrica sp. nov. and T. sablensis sp. nov.) and four from Canadian Pacific Ocean coastal waters (T. inornata sp. nov., T. multipora sp. nov., T. gwaii sp. nov. and T. curvata sp. nov.). These discoveries more than double the number of known marine species of this genus from four to ten. The scale structures of all differ significantly from those of previously known species and therefore warrant erection as new species. Amended descriptions of two previously little-known freshwater species (T. triangulata and T. nigeriensis) are provided based on specimens found in freshwater ponds and lakes in Ontario, Lanada, and provide evidence refuting the recent published proposals to transfer T. triangulata back to the photo-autotrophic genus Chrysosphaerella and to transfer T. nigeriensis to the related thaumatomonad genus Reckertia. Until now, all known species of Reckertia (including several taxa previously classified in Thaumatomastix) were marine. This paper describes the first known freshwater species of Reckertia (R. hindoni sp. nov.) found in two separate Ontario ponds. The similarities and differences among many of the marine and freshwater species of Thaumatomastix suggest a common ancestor but significant evolutionary divergence over time and space. © 2012 Marine Biological Association of the United Kingdom. Source


Nicholls K.H.,S 15 Concession 1 | Hoyle J.A.,Ontario Ministry of Natural Resources | Johannsson O.E.,Canadian Department of Fisheries and Oceans | Dermott R.,Canadian Department of Fisheries and Oceans
Journal of Great Lakes Research | Year: 2011

Thirty-two biological variables (taxonomic and/or functional groups) representing the four major communities, phytoplankton, zooplankton, benthos and fish, characterizing the upper Bay of Quinte (Lake Ontario) ecosystem, were assembled for the 27-year period, 1982-2008. Coincident regime shifts were detected in phytoplankton, benthos, and fish in 1995, which was just after invasive zebra mussels (Dreissena spp.) became established in the bay in 1993-1994. Two independent methods were used to detect these shifts: 1) principal components analysis followed by a Regime Shift Detector test for a change point in the running mean of the first principal component scores and (2) measurements of significant difference between pre- and post-Dreissena ecosystem structure based on measures of Bray-Curtis community similarity. Although a statistically significant shift was not detected in the zooplankton community by itself, zooplankton variables were instrumental in the overall ecosystem shift, determined for the combined four communities. All 32 variables were ranked for their individual contribution to the difference between the pre- and post-Dreissena ecosystem structures. The resolution of two distinct ecosystem structures, pre- and post-Dreissena, was greatly improved after employing a novel method of variable optimization that involved a selective and sequential removal of variables contributing least to the statistical difference between pre- and post-Dreissena ecosystem structures. The resultant 20-variable subset defined a 1995 ecosystem regime shift at very high level of statistical confidence (ANOSIM-R = 0.970). © 2010 Elsevier B.V. Source


Nicholls K.H.,S 15 Concession 1 | Carney E.C.,12421 6th Line
Aquatic Ecosystem Health and Management | Year: 2011

The objective of this contribution is to further the understanding of long-term (37 years) changes in the composition and biomass of the phytoplankton of the Bay of Quinte (northeastern Lake Ontario), especially those changes associated with the simultaneous point-source phosphorus loading reduction/white perch winter kill of early 1978 and the establishment of dreissenid mussels in the mid-1990's. The relatively shallow and polymictic upper bay has facilitated the ice-free period domination of the phytoplankton by meroplanktonic diatoms (especially Aulacoseira spp.); while a more balanced representation by several algal Divisions has characterized the thermally stratified, dimictic lower bay. At all three stations (upper bay, middle bay and lower bay), phytoplankton biomass declined and community similarity decreased after both the phosphorus loading and the Dreissena interventions, but the biomass changes associated with the P load reduction were greater than those associated with Dreissena establishment. Conversely, the loss of phytoplankton community similarity after Dreissena establishment was greater than that associated with P loading reduction at all three stations. The Remedial Action Plan phytoplankton objective of 4-5 mm3 l-1 (May-October mean) has been met inconsistently since the establishment of Dreissena. The post-Dreissena period, however, was also characterized by occasional very high biomass values for the potentially toxic cyanoprokaryote (blue-green alga) Microcystis, as well as by a dramatic decline in the bloom-forming bluegreen Aphanizomenon, and the near extirpation of the diatoms, Tabellaria and Synedra spp. A partially synthetic phytoplankton community was constructed using data taken from three local aquatic systems (Trenton Bay, upper Hay Bay and West Lake). This might be used as a reference against which past and future changes in the upper Bay of Quinte phytoplankton can be compared and evaluated. © 2011 AEHMS. Source


Nicholls K.H.,S 15 Concession 1
Methods in Ecology and Evolution | Year: 2011

1. Human activities have led to ecological regime shifts, first revealed at the community level in ecosystems. A regime shift in a biological community is a sudden change in the relative contributions of several taxa, resulting in a post-shift state that remains stable over the long term with a structure that is outside the boundaries of the 'normal' pre-shift variability. Most methods for regime shift detection are based on univariate statistics (e.g. commercial fish catch data, sea surface temperature anomalies). Multivariate methods suitable for identifying change in multi-species communities can be used to identify regime shifts in communities. 2.In this paper, I use a 37-year record (1972-2008) of phytoplankton in the Bay of Quinte (northeastern Lake Ontario) to demonstrate the use of several largely independent data analysis methods that are shown here to concur in their output. Among the most powerful procedures is an approach that models the anomalies around long-term Grand Mean and reference-point community structures that were compared to annual structures using Bray-Curtis community similarity coefficients. CUSUM plots of model residuals, segmented regression analysis and other tests are all useful to identify the location of break-points in records of anomalies. Follow-up significance testing was performed separately with permutation tests. Improved sensitivity of these techniques when applied to highly seasonal data was demonstrated after extraction of seasonal components as periodic functions. 3.Statistically significant shifts in the Bay of Quinte phytoplankton were detected in the year following an approximate 50% reduction in point-source phosphorus loading in early 1978 and again immediately after the establishment of invasive dreissenid mussels in the mid-1990s. Associated with this second intervention was an increased representation by species of the potentially toxic Cyanoprokaryote Microcystis, and dramatic declines in some diatom species, with significant implications for human use and food web function. 4.This paper provides a 'tool box' of methods (most freely available on the WWW) for those needing to distinguish between true shifts and normal inter-annual variability in biological communities. Ability to measure statistically significant change in communities can lead to enhanced understanding of cause-effect relations and to enhanced capabilities for prediction of change. © 2011 The Authors. Methods in Ecology and Evolution © 2011 British Ecological Society. Source


Zoelucasa sablensis n. gen et n. sp. is a small heterotrophic flagellate housed within a pyriform lorica of relatively large imbricate,circular siliceous scales. It was found in near-shore benthic sand/seawater samples of both the Pacific and Atlantic Oceans (west and east coasts of Canada; salinity = 32-33 ppt). The median length and width of the lorica was 18 and 11 μm, respectively (n = 29). This taxon lacks chloroplasts and swims with a slow zig-zag motion controlled by a short (5-7 μm long), anteriorly-directed flagellum and a longer trailing flagellum, 15-20 μm in length. Its classification within the phylum Cercozoa (most likely, Class Imbricatea) is tentative, as there are no known morphological homologues (discoidal, overlapping siliceous plate-scales forming a test or lorica enclosing a heterotrophic flagellate). Further study of cultured and wild material, including a search for other possible non-flagellate (e.g. amoeboid?) life history stages, TEM examination of cell sections, and rDNA sequencing will most certainly provide more opportunities for a justifiable classification, possibly including a new Order. Source

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