Impact of Nutrient Loading and Eurasian Watermilfoil on Phytoplankton Communities Among Channels of the Les Cheneaux Islands, Lake Huron

Authors: Jade E. Ortiz¹ , Amy M. Marcarelli¹ , Gary L. Fahnenstiel¹ , Rob A. Smith²

Author Affiliation: ¹ Michigan Technological University, ²Les Cheneaux Watershed Council

Journal: Unpublished; Cooperative Project between LCWC & MTU; 2014

Abstract: Water quality is a concern in channels of the Les Cheneaux Islands, but little is known about phytoplankton communities, which form the base of the pelagic food web.

This report provides a basis for understanding primary producer responses to nutrient loading and Eurasian watermilfoil (Myriophyllum spicatum) management efforts in the waterways of the Les Cheneaux Islands.

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; December 2001

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; February 24, 2021

Abstract:

The Les Cheneaux Watershed Council has monitored water quality variables within the Les Cheneaux Islands (LCI) since 2001, a project sponsored by the Les Cheneaux Islands Association. A period from 2013 through 2020 was different from previous years in that the Lake Huron rise (LHr) continued every year. Resulting LHr of 171 cm ( 67.4 in) occurred from a record low level in January 2013 to a record high level during the summer months of 2020. Water temperature profiles during the sampling season from May through Sep decreased 5°C ( 9.5°F) during the LHr. This study examines the relationship between L Huron level and LCI temperatures during those eight years. It is possible that the simple incursion of cooler LH water into the LCI channels could have could have contributed to lower seasonal temperatures. If that hypothesis is true, then such volumes of cooler, low-nutrient LH water could affect food webs within the islands which could have long lasting environmental effects on aquatic systems, especially the aquatic plant community. A follow-up examination of the phosphorus and plankton variation during the same period will follow this study.

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; February 2021

Abstract:

Variation of Great Lakes water levels in the four-to-five foot range have been recorded since the mid-1800s. No lake level shifts of almost six feet over a short eight-year period have been recorded during that time. The Les Cheneaux Watershed Council (LCWC) took advantage of this unprecedented event to monitor plankton, phosphorus and temperature changes during the recent rapid Lake Huron (LH) rise. Each year, data and water specimens were collected monthly by LCWC from May through Sep and samples were subsequently analyzed at the Univ MI Biological Station, Douglas Lake. Water level increase within the Les Cheneaux Islands from an historic low in 2013 through the summer of 2020 to the historic high is shown in the figure below. LH increased almost six feet, water temperature dropped, total phosphorus concentrations decreased almost sixfold and plankton density decreased fivefold. Although annual variation occurred, trendlines for all three variables monitored had a downward slope during the study. Temperature decline attributed to the inflowing, cooler LH water appears to have decreased plankton metabolism and, therefore, overall plankton density. A dilution effect from the inflow of low-nutrient LH water would be expected to limit available phosphorus as a plankton energy source. However any phosphorus dilution was apparently offset by higher water levels suspending organics from the shorelines, which then became available as a plankton food source. Plankton growth deficits due to phosphorus availability were not obvious. These same variables will continue to be monitored as Lake Huron waters recede.

Authors: Arielle Earn, Kennedy Bucci, Chelsea M. Rochman

Author Affiliation: 

University of Toronto, Department of Ecology and Evolutionary Biology, St. George Campus, Toronto, Ontario, Canada

Journal: Journal of Great Lakes Research

Abstract: Plastic pollution is ubiquitous in freshwater systems worldwide, and the Laurentian Great Lakes are no exception. We conducted a systematic review to synthesize the current state of the literature on plastic pollution, including macroplastics (>5 mm) and microplastics (<5 mm), in the Great Lakes.We completed a second systematic review of plastic pollution and its impact on freshwater ecosystems in general to inform how plastic in the Great Lakes may impact wildlife. Among studies published in the literature, we found 390 tested effects, 234 (60%) of which were detected and 156 (40%) of which were not; almost all of the freshwater effects (>98%) were tested on microplastics. Based on a subset of these papers, we found that the shape and size of a particle likely affects whether an effect is detected, e.g., more effects are detected for smaller particles.

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; February 10, 2023

 

Abstract:

A study published in 2021 tracked the changes in nutrients, plankton and temperatures in Les Cheneaux Islands (LCI) waters during a seven-year period from 2013 through 2020 in which L Huron (LH) increased to a record high level and at a record rate (Ref. 1). The LH level has decreased during both 2021 and 2022 since the record high was documented in 2020 by the Army Corps of Engineers (USACE). This report quantifies changes in the same three variables during the period of decline that were monitored during the time of rapid rise.

Seasonal water temperatures within LCI channels increased from 2020 through 2022 by 1.5°-2.5° C (3.2°-5.3° F) during which time LH level declined by 66 cm (26 inches).   With lower depths in the LCI channels one could expect water column nutrient concentrations to increase. As a result of warmer water and increased nutrients one could also expect plankton densities to increase. This was not the case. Rather, plankton density decreased by about 20% from 2020; the year of record high LH level.

It is not obvious why the plankton density dropped during a time of seasonal water temperature and nutrient increases. Conversely, a plankton concentration increase could be expected under these circumstances. One possible explanation is that micronutrients provided in the LH water were reduced in concentration due to the lower LH level. Another possibility is that the three year observation is not sufficient to accurately track trends of the complex water chemistry dynamics between LH and the LCI channels.  Monitoring of these variables continues.

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; January 30, 2023

 

Abstract:

Les Cheneaux waters continue to be rated as excellent for recreational purposes based on analytical results from water samples collected during the summer of 2022. As has been the case since 2001, areas of our channels that have historically been rated as low in nutrients and algae concentrations have remained so. Similarly, areas which have been rated as higher in nutrients and algae densities have also remained in this category.

Trophic History of Les Cheneaux Waters: 2001-2012

Authors: R. A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; January 13, 2013

Abstract: Factors that contribute to the growth of aquatic plants and affect recreational water quality have been studied by the Les Cheneaux Watershed Council and the Les Cheneaux Islands Association since 2001. During this survey period the recreational water quality has been classified as excellent according to limnology, or water scientist, criteria. The trophic state, or the potential of nutrients to support algal or plankton biomass, has remained essentially the same between 2001 and 2012.

Phosphorus and Phytoplankton Dynamics in the Les Cheneaux Islands during a Rapid Rise in Lake Huron Water Level

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; April 2016

Abstract: The LCWC studies nutrients in the water, primarily phosphorus, and the density of free-floating algae, phytoplankton, to get an idea of what the season’s weed growth might be like. Rooted aquatic weeds like Eurasian watermilfoil get most of their nutrients from the bottom sediments and algae get their nutrient directly from the water.

From 2013 to the end of 2015 we experienced a 37 inch rise in lake levels. An unprecedented lake rise for a two year period, that resulted in a 30% dilution rate. What effect does that amount of dilution have on the weed growth, phytoplankton growth and availability of nutrients? That is what this paper addresses.

Rapid decline of phytoplankton in the Les Cheneaux Islands during a five-year period.

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; April 2018

Abstract:

The balance between plankton and rooted aquatic plants is critical to a healthy aquatic ecosystem. Moreover, plankton species and population densities are important to the aquatic food web. Estimates of phytoplankton (free-floating algae) density for this study were made by measuring photosynthetic chlorophyll which was chemically extracted from phytoplankton contained in water samples collected monthly throughout Les Cheneaux during a five month period each year. Resulting chlorophyll concentrations, in this case Chlorophyll-a, were used to estimate phytoplankton population densities throughout the study. Following a 2013 peak concentration in Chlorophyll-a (Chl-a) ⁽¹⁾ recorded from twelve different sites throughout LCI, a steady, annual decline in Chl-a was observed through 2017.

Results from Island Wide Water Monitoring, Summer 2018

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; April 2019

Abstract:

Ratings of 2018 water samples fell within expected nutrient ranges for the inner and outer island zones of the Les Cheneaux Islands and reflected high quality water for recreational purposes as has been the case since this type survey began in 2001. Analytical values for all test sites were within range of samples quantified by the Univ Mich Biological Station during the previous five seasons. The relationship of three variables: Total Phosphorus, Soluble Reactive Phosphorus and Chlorophyll-a was different than expected in 2018. Samples from the same test sites will be compared in 2019 to determine if 2018 result were an exception to past findings or an indication of a new
trend. Thanks to those who helped with sample collections during the season: Scott Myers, Lynn Wolters, John Bentley, Neil Williams and Mike Jellison.

Author: R.A. Smith

Author Affiliation: LCWC

Journal: Unpublished Report

Abstract

A primary nutrient for algae and weed growth has remained within a limited range during the past seven years.

Abstract: Three variables monitored during annual LCWC sampling of Les Cheneaux waters include Total Phosphorus (TP), Soluble Reactive Phosphorus (SRP) and Chlorophyll-a (Chl-a). Phosphorus is a growth limiting nutrient for phytoplankton (free-floating algae). Therefore, the availability of phosphorus is a primary factor in determining how much algae is present during any given year. SRP is a readily used form of phosphorus and can be quickly depleted during times of rapid algae growth. The relationship of these variables is an indicator of Les Cheneaux water chemistry stability. Observed values for these variables each year remain within the upper oligotrophic index signaling the nutrient fluctuation to be within normal Les Cheneaux variation. The stability of TP, SRP and Chl-a demonstrates the resiliency of our wetland ecology, even during years of continued increase in the Lake Huron level of 63 inches ( 160 cm) during this reporting period.
A follow-up paper will be developed to compare SRP/TP ratios of Les Cheneaux waters those of L Huron open waters to deter-mine if the seven-year rise in lake level impacted LCI ratios.

Author: R.A. Smiith

Author Affiliation: LCWC

Journal: Unpublished Report

Abstract

Les Cheneaux waters remain of a highly desirable quality for recreational use.

Ratings of 2019 water samples fell within expected trophic (nutrient) ranges for inner and outer island zones of the Les Cheneaux Islands. Variables quantified for Les Cheneaux water samples were: Total Phosphorus (TP), Soluble Reactive Phosphorus (SRP) and Chlorophyll-a (Chl-a).
TP and SRP values were found to be about equal in concentration. Chlorophyll-a was used as an indirect measure of phytoplankton concentration. As Chl-a values increase the SRP is metabolized and, therefore, decreased. Seasonal 2019 temperatures ranged from an average of 10.5 C (51 F) for the inner island zones to 16.5 C (62 F) for the outer island zones. Water clarity remained high to a point that the Secchi disk could be read when lying on the bottom at sites 2, 4a,8 and 9 where the depth ranged from 10ft to 45ft.

Author: R. A. Smith

Author Affiliation: LCWC

Journal: Unpublished Report

Abstract

Les Cheneaux waters remain of a highly desirable quality for recreational use.

Ratings of 2019 water samples fell within expected trophic (nutrient) ranges for inner and outer island zones of the Les Cheneaux Islands. Variables quantified for Les Cheneaux water samples were: Total Phosphorus (TP), Soluble Reactive Phosphorus (SRP) and Chlorophyll-a (Chl-a).
TP and SRP values were found to be about equal in concentration. Chlorophyll-a was used as an indirect measure of phytoplankton concentration. As Chl-a values increase the SRP is metabolized and, therefore, decreased. Seasonal 2019 temperatures ranged from an average of 10.5 C (51 F) for the inner island zones to 16.5 C (62 F) for the outer island zones. Water clarity remained high to a point that the Secchi disk could be read when lying on the bottom at sites 2, 4a,8 and 9 where the depth ranged from 10ft to 45ft.

Author: R.A. Smith

Author Affiliation: LCWC

Journal: Unpublished Report April 2020

Abstract:

From 2013 through 2019 water levels in the Les Cheneaux Islands have risen 63 inches (160 cm). During the same period, aver- age water temperatures dropped 3.5^o to 4.5 ^o Centigrade ( 8^o Fahrenheit). It was expected that these shifts in conditions would result in a related downward shift in phosphorus concentrations that are monitored each summer as part of our water quality program. This was not the case, however. Phosphorus values appeared to change little. Neither did it make sense that, while phosphorus concentrations remained level, the algae population densities decreased. Phosphorus is a primary food source for algae and if the phosphorus levels remained level, then algae concentrations would have been expected to remain within a constant range as well. Algae populations measured were phytoplankton, the free-living plankton that are found dispersed in the water column. The following paper examines this apparent disconnect between the expected and the actual.

ACKNOWLEDGMENTS:

Sincere appreciation is expressed to several people involved during this lengthy study, they include:

• Editors of this document: Bill Kurtz, Scott Myers and Ed
• Sample analysis: Tim Veverica and staff at the Univ Mich Biol Station at Douglas
• Sample collection: Scott Myers, Lynn Wolters, Neil Williams, Mark Clymer, Mike & Laurel Jellison, Fred and Joyce Moore, Barb Smith, Mary Baker, Dave Dunn.

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; December 10, 2020

Abstract:

Remote sensing probes were installed in Pearson Creek and Beavertail Creek at the end of October, 2020, in a collaborative program involving LSSU, the ISD and Cedarville High School. Data recorded by the probes will be used to compare water characteristics of the two creeks over time.

Authors: R.A. Smith

Author Affiliation: LCWC

Journal: LCWC Report; December 10, 2020

Abstract:

Low phosphorus and low planktonic algae concentrations recorded during 2020 seasonal Les Cheneaux water monitoring were similar in productivity range, or nutrient rating, to the open waters of Lakes Huron and Superior which are considered pristine waters with low nutrients and lower algal biomass. Given the varied concentrations of phosphorus and plankton among test sites, the change was essentially balanced, resulting in a net neutral change for the 2020 season. Barring major environmental impacts, Les Cheneaux waters can be expected to remain desirable in quality of the fishery and for recreational activities for coming years.