Sunderland, Canada
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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.

Nicholls K.H.,S 15 Concession 1
Aquatic Ecosystem Health and Management | Year: 2012

Three independent methods of time-series analysis were applied to a 37-year record of total phosphorus and chlorophyll-a data collected at four sampling stations representing the upper, middle and lower sections of the Bay of Quinte, NE Lake Ontario, Canada. The three methods were used to build consensus around the significance of the apparent declines in total phosphorus (TP) and chlorophyll-a (Chl-a) concentrations following two interventions: (1) point-source phosphorus loading reductions of about 50% to the upper bay in the winter of 1977-1978 and (2) the establishment of Zebra Mussels (Dreissena spp.) in the early to mid-1990's. The methods were applied to May to October monthly means and included: (1) nonparametric tests that accounted for persistence and seasonality and determined the statistical significance of step-trends, (2) ARIMA-Intervention modelling that produced forecasts into post-intervention time periods that were compared statistically to measured data and (3) regime shift detection for identifying the significance of persistent steps after removal of the seasonal components of the data series (modelled as periodic functions). Strong gradients in total phosphorus (TP) and Chl-a concentrations between the upper and lower Bay of Quinte still existed three decades after reductions in point-source loadings of TP to the upper bay, where, during 2000-2008, May-October average TP was 3.8 times higher and Chl-a, 2.9 times higher than in the lower bay. The Remedial Action Plan May-October TP objective of 0.030 mg l-1 for the upper Bay of Quinte was not achieved consistently in recent years. Concurrence among the data analysis methods suggests that the relative decreases in the upper bay TP (31%) and Chl-a (37%) after phosphorus loading reductions were greater than in the lower bay (0% and 10%, respectively). The relative decreases in the upper bay TP (0%) and Chl-a (29%) associated with Dreissena establishment were less than those measured in the lower bay (20% and 50%, respectively). © 2012 Copyright Taylor and Francis Group, LLC.

Nicholls K.H.,S 15 Concession 1 | Torok J.K.,Eötvös Loránd University
European Journal of Protistology | Year: 2016

The morphology of tests (“shells”) representing populations of the small testate amoeba Cyphoderia laevis Penard, 1902 (Cercozoa, Euglyphida) from Canada and Hungary was quantified. Despite often considerable variation the cross-sectional shape of tests, multivariate statistical analysis confirmed the general uniformity of test morphology within populations and between populations at both local (regional, inter- and intra-watershed) scales and over inter-continental scales (Canada and Hungary). Corrections are suggested to recently published misidentifications of C. laevis as Corythionella georgiana Nicholls. The differences between these two taxa are subtle, but significant, and are emphasized here to help preclude similar errors in the future. Schaudinnula nana Badewitz, 2003 is shown to be a superfluous synonym for Cyphoderia laevis. Cyphoderia truncata Schulze, 1875 has some similarities to C. laevis, but its status remains unresolved. Some preliminary reservations are expressed about the classification of Cyphoderia laevis within the genus Cyphoderia owing mainly to its Corythionella-like scale structure and other characteristics of its test that appear to be outside the “usual” range found in other Cyphoderia species. © 2016 Elsevier GmbH

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.

The rarely reported red pigmented dinoflagellate, Woloszynskia pascheri, is described from frozen surface waters in Ontario, Canada. New information based on light microscopy (LM) is provided on cell organelles (dinokaryon, chromosomes, pigment droplets and ectoplasmic vesicular layer), the thin-walled ice-bound pellicle cysts and thick-walled summer resting cysts. An earlier published suggestion that W. pascheri has morphology similar to that of Gymnodinium cryophilum (Wedemayer, Wilcox et Graham) G. Hansen et Moestrup is refuted. The process of red ice formation depends on a number of weather-related and other environmental factors. The most important of these being a mid-winter thaw that creates pathways (cracks and melted areas of ice) for passage of swimming cells from the water underlying the ice to water on the surface of the ice. In thin-walled ice-bound pellicle cysts, W. pascheri remained viable at ambient air temperatures lower than −20°C for several days and suggests a unique biochemical physiology that needs research. A summary of the historical classification of this species reveals a tumultuous past and the continuing assignment of this species within the genus Woloszynskia appears doubtful, given the rapidly improving state of knowledge about the fine structure and molecular biology of many other similar species. © 2016 Springer International Publishing Switzerland

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.

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.

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.

Nicholls K.H.,S 15 Concession 1
Journal of Great Lakes Research | Year: 2016

The rotifer Lecane monostyla (Daday, 1897), widely distributed in equatorial and subtropical regions of the world, is generally considered to be a warm-water stenotherm. This note reports this species in a nearshore benthic sample from Mazinaw Lake, Ontario Canada, a 145 m deep oligotrophic lake with a 4-month annual winter period of ice cover. © 2016 International Association for Great Lakes Research.

In 1961, the testate amoeba Nebela kivuense Gauthier-Lièvre et Thomas, 1961 was described for the first and only time from an area near Lake Edward in the Democratic Republic of the Congo (at 0.002° N Latitude). The lack of recent reports of this species, despite exhaustive surveys of the testate amoebae fauna of the major continents of the world, suggested that N. kivuense was a rare species perhaps endemic to a small, local equatorial region of the African continent. This paper reports its rediscovery from two wetland-conifer forest ecosystems in southern Ontario, Canada (at 44° N Latitude), thus changing dramatically our previous perception of its very restricted global distribution. This has implications for the idea held by many students of biogeography that there is a special category of microscopic protists that contains truly rare species and their rarity, perhaps together with specific habitat requirements and tolerances, limits opportunities for dispersal around the world. The N. kivuense story is a clear example of the dangers of inferring endemism from rarity. © 2015, Jagiellonian University. All rights reserved.

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