The ecological history of Lake Ontario according to phytoplankton

Abstract

Lake Ontario's condition has fluctuated since European settlement, and our understanding of the linkages between observed ecosystem shifts and stressors is improving. Changes in the physical and chemical environment of the lake due to non-indigenous species, pollution, sedimentation, turbidity, and climate change altered the pelagic primary producers, so algal assessments have been valuable for tracking long-term conditions. We present a chronological account of algal assessments to summarize past and present environmental conditions in Lake Ontario. This review particularly focuses on pelagic, diatom-based assessments as their fossils in sediments have revealed the combined effects of environmental insults and recovery. This review recaps the long-term trends according to three unique regions: Hamilton Harbour, the main lake basin, and the Bay of Quinte. We summarize pre-European impact settlement; eutrophication throughout most of the 20th century; subsequent water quality changes due to nutrient reductions; and filter-feeding dreissenid colonization and contemporary pelagic, shoreline, and embayment impairments. Recent data suggest that although phytoplankton biovolume is stable, species composition has shifted to an increase in densities of spring eutrophic diatoms and summer cyanobacteria. Continued monitoring and evaluation of historical data will assist in understanding and responding to the natural and anthropogenic drivers of Lake Ontario's environmental conditions.

Subfossil and periphytic diatoms from the upper Paraná river, Brazil: last ~1000 years of a transition period

“…Ecological information: species generally of planktonic habitat, but also found in the periphytic community. Dominant in shallow lakes, occurring in oligotrophic to eutrophic waters, tolerate temperatures of 0 to 30 o C (Van Dam et al 1994, Moro & Fürstenberger 1997, Estepp & Reavie 2015. Species of Aulacoseira genus has heavy silicified cells with a high sinking rate (characteristic clearly observed in the Aulacoseira italica of this study), therefore, this species requires turbulence to maintain its presence in the water column (Bradbury 1975).…”

“…Dominant in shallow lakes, it occurs in mesotrophic to eutrophic waters but is commonly found in eutrophic waters. This species occurs in alkaline waters and tolerate temperatures of 15 to over 30 o C (Van Dam et al 1994, Moro & Fürstenberger 1997, Taylor et al 2007, Zalat & Vildary 2007, Kiss et al 2012, Estepp & Reavie 2015. According to some works, this species is associated with water column mixing, high flood conditions and depth variations, and physical alterations as erosion events, turbulence, and deforestation (Zalat & Vildary 2007, Dong et al 2008, Costa-Böddeker et al 2012, Fontana et al 2014.…”

Deforestation caused abrupt shift in Great Lakes nitrogen cycle

“…Because Lake Ontario receives a large amount of its water from land runoff, it is particularly sensitive to broader ecological processes and human disturbances occurring across the watershed, particularly in terrestrial and riparian zones. Moreover, the significant and highly visible environmental degradation of Lake Ontario's watershed throughout the 20 th century, as well as its close proximity to major population centers, has spurred considerable research into its ecological structure (e.g., Bogue 2001;Meyers 2003;Estepp and Reavie 2015;Stewart et al 2016). For this reason, the lake has a relatively well-documented ecological and biogeochemical history, with numerous isotopic studies of modern fish identifying recent trends in community structure, trophic dynamics, and energy flows (Kiriluk et al 1995;Lumb and Johnson 2012;Rush et al 2012;Yuille et al 2015;Colborne et al 2016;Fera et al 2017).…”

The Analysis of Phytoplankton Abundance Using Weibull Distribution (A Case Study in the Coastal Area of East Yapen in the Regency of Yapen Islands, Papua)

“…namely grazing. The main cause which results in changes in the population of phytoplankton is the intensive grazing activity by zooplankton (Nybakken, 1992;Estepp & Reavie, 2015).…”