Development of Primary Production-Light Limitation Metrics for Monitoring Water Quality in Utah Lake

Abstract

Utah Lake has undergone substantial anthropomorphic induced degradation resulting in major ecosystem shifts (Scheffer et al. 2001) following manifest destiny centric Mormon settlement in the mid 1800’s that continues to this day (Richards and Miller 2017, 2019a, 2019b, 2019c). One of the most important ecosystem shifts was from a benthic- driven- primary production state to a water-column- periphyton- primary production state (ongoing paleolimnological studies by BYU and USU researchers). Several important factors contribute(d) to this ecosystem shift: transition from a natural water body to highly regulated reservoir, chronic water level regulation and diversion, heavy nutrient loads and other pollutants, loss of native macrophytes (emergent plants), loss of native mollusks (snails, clams, mussels), loss of native fishes, introduction of invasive fishes including carp, habitat degradation, etc. (Richards and Miller 2017, 2019a, 2019b, 2019c). The shift from benthic primary productivity to water column primary productivity has resulted in chronic algal blooms including cyanobacteria blooms, loss of native biodiversity, increased light limitation, and reduced resistance and resilience to perturbation. One of the primary ambitions of water quality managers and citizens of Utah is to transition Utah Lake from a turbid, eutrophic condition back to a less turbid, less eutrophic, less cyanobacteria influenced condition . Some citizens and state agencies are also keen on reestablishment of the lake’s native flora and fauna, including macrophytes, fishes, and mollusks. This technical report discusses some pertinent metrics to monitor these changes.

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Version 1.1
Development of Primary Production- Light
Limitation Metrics for Monitoring Water
Quality in Utah Lake
Technical Memo
November 17, 2021
Atmosphere
Water Column
tmosphere
Sediment (Benthos)
Nutrient Deposition
Phytoplankton
Primary Production
Periphyton (Benthic Algae)
Primary Production
Epiphytes
Growing on
Macrophytes
Macrophytes
Light Attenuation
By
David C. Richards, Ph.D.
OreoHelix Ecological, Vineyard UT
84059
Phone: 406.580.7816
Email: oreohelix@icloud.com
Nutrients
To
Wasatch Front Water Quality Council
Salt Lake City, UT
Bivalve filter-feeding
Gastropod
grazing

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Introduction
Utah Lake has undergone substantial anthropomorphic induced degradation resulting in major
ecosystem shifts (Scheffer et al. 2001) following manifest destiny
1
centric Mormon settlement in
the mid 1800’s that continues to this day (Richards and Miller 2017, 2019a, 2019b, 2019c). One
of the most important ecosystem shifts was from a benthic- driven- primary production state to a
water-column- periphyton- primary production state (ongoing paleolimnological studies by BYU
and USU researchers). Several important factors contribute(d) to this ecosystem shift: transition
from a natural water body to highly regulated reservoir, chronic water level regulation and
diversion, heavy nutrient loads and other pollutants, loss of native macrophytes (emergent
plants), loss of native mollusks (snails, clams, mussels), loss of native fishes, introduction of
invasive fishes including carp, habitat degradation, etc. (Richards and Miller 2017, 2019a,
2019b, 2019c). The shift from benthic primary productivity to water column primary
productivity has resulted in chronic algal blooms including cyanobacteria blooms, loss of native
biodiversity, increased light limitation, and reduced resistance and resilience to perturbation. One
of the primary ambitions of water quality managers and citizens of Utah is to transition Utah
Lake from a turbid, eutrophic condition back to a less turbid, less eutrophic, less cyanobacteria
influenced condition
2
. Some citizens and state agencies are also keen on reestablishment of the
lake’s native flora and fauna, including macrophytes, fishes, and mollusks.
A quick superficial review of lake zones defined by limnologists as it relates to Utah Lake is
appropriate. The zones we are most interested in for this memo are the littoral vs limnetic zones
and the two basic light zones, photic and aphotic (Figure 1).
1
Manifest destiny: The widely held cultural believe that white American settlers were/are divinely ordained to settle
the entire continent of North America.
2
Although nutrients are the primary cause of algal blooms in Utah Lake it is the state of the system which
determines the result of this process. “The basic mechanism is that cyanobacteria are the superior competitors under
conditions of low light, but also promote such conditions, as they can cause a higher turbidity per unit of phosphorus
than other algae. This mechanism of hysteresis explains the resistance of cyanobacteria dominance in shallow lakes
to restoration efforts by means of nutrient reduction alone.” (Smith et al., 1987, Scheffer et al. 2007, Dokulil and
Teubner 2000).

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Figure 1. Simplistic diagram of different limnological zones of a lake. https://kascomarine.com/wp-
content/uploads/2016/02/C9_fig_9.3-aquatic-science-texas.jpg.
The littoral zone is the area of a lake where rooted aquatic macrophytes (plants) are established.
The limnetic zone is where rooted plants do not exist. Utah Lake currently has a very poorly
functioning littoral zone primarily due to the lake being managed as a reservoir with
unpredictable shoreline water level fluctuations, wind and wave action scouring, high suspended
solid and algal turbidity, and to a lesser extent carp bioturbation.
The photic zone (also known as euphotic) is the depth at which light penetration is sufficient for
photosynthesis and the aphotic zone is the zone below the photic zone and insufficient for
photosynthesis. The lower limit of the photic zone is almost universally considered as the depth
at which < 1% light energy occurs (Kirk 2011). Utah Lake has a very shallow photic zone due to
suspended solid and algal turbidity that varies spatially and temporally. Estimated photic zone
depth using Secchi disk measurement (see Metrics section) has shown that it is often only
between 20 and 40 cm and except for the very shallowest locations on the lake (or sometimes
under ice cover) photosynthetically available light does not penetrate to the benthos to allow for
benthic primary production in which case, only heterotrophic bacterial production occurs
(Richards and Miller unpublished data). One of our primary goals in 2022 is to measure light
attenuation in Utah Lake using a PAR meter and mapping diurnal, seasonal, and spatial patterns
of the photic/aphotic zones (see Metrics section).
Benthic Primary Production
Benthic periphyton (algae) ecosystem functions are numerous and include significant
contributions to gross primary production (Velasco et al. 2003) (often > > 46% primary
productivity (Vadeboncoeur et al. 2002), trophic interactions (Moulten et al. 2004), ecosystem

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engineering (e.g., biostabilization of sediments; Dodds 2003; Droppo et al. 2007; Spears et al.
2007b), regulation of nutrient cycling across the sediment–water interface (Dodds 2003,
Poulickova et al. 2008, Vadeboncoeur et al., 2003), and are vastly underappreciated contributors
to pelagic fisheries (Vadeboncoeur et al. 2002). Periphyton assemblages can also increase
retention of nutrients. According to Dodds (2003), periphyton can:
• Remove nutrients from the water column and cause a net flux of nutrients toward the
sediments,
• slow water exchange across the sediment/water column boundary thus decreasing
advective transport of P away from sediments,
• intercept nutrients diffusing from the benthic sediments or senescent macrophytes,
• cause biochemical conditions that favor P deposition and can,
• trap particulate material from the water column (Adey et al. 1993).
Eutrophication is the most important determinant of shifts from benthic algal production to
phytoplankton production in shallow lakes including Utah Lake, however many other factors are
involved (Vadeboncoeur et al. 2002, 2003, 2008, Dodds 2003), including those listed in the
introductory paragraph.
Despite the importance of benthic algae to lake dynamics that has been known to limnologists
for almost one hundred years (Forbes 1925, Lindeman 1942, Vadeboncoeur et al. 2002), benthic
algae primary production and ecosystem services are now all too often neglected in conceptual or
empirical models of lake ecosystem function and food web models (Vadeboncoeur et al., 2008).
Dodds (2003) summarized the role of periphyton in phosphorus retention in shallow freshwater
aquatic systems (see above). The following (Figure 2) is a diagram from Dodds (2003)
illustrating nutrient flux to and from sediments as modified by periphyton.

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Figure 2. Nutrient flux to and from sediments and water column as modified by periphyton and epiphyton. Taken from Dodds
(2003).
It should be noted that a transition from water column primary production to benthic primary
production is not without potential adverse conditions. For example, given that Utah Lake
nutrient concentrations tend to remain in equilibrium/buffer between sediments, water column,
and atmospheric deposition; increasing water clarity could very well result in major green algal
blooms such as Cladophora sp. (Figure 3).
Figure 3. The green algae, Cladophora sp. that we hypothesize could bloom in Utah Lake if turbidity decreases from
(mis)management actions. Right image: http://www.turtles.org/asp00900.jpg. Bottom Leftimage: https://cpb-us-
w2.wpmucdn.com/sites.uwm.edu/dist/e/211/files/2019/12/Control-Algae-1.jpg.

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Although Cladophora sp. are native to Utah Lake and do not produce toxins, many consider this
to be a nuisance species. However, Cladophora sp. are well known to filter suspended solids
from the water column, have high water column nutrient demand, and transfer large amounts of
nutrients from the water column to the sediments upon senescence. Cladophora sp. blooms are
also spatially and temporally (seasonally and annually) variable and may eventually be reduced
from competition with other successional algae. Management trade- offs are inevitable and the
ecosystem services that some algal taxa provide need to be considered. Unanticipated
consequences are also possible. Many unanticipated and expected but unwanted consequences
such as Cladophora sp. blooms can be mitigated by using a holistic biomanipulation approach to
help transition Utah Lake from water column to benthic primary production (see following
sections).
Assistants to Benthic Primary Producers
A transition from water column primary production to benthic primary production in Utah Lake
will likely prove impossible without major reductions in external source inputs of nutrients
(Scheffer et al. 2001) including those from tributaries, water treatment facility effluent, and
atmospheric deposition. Atmospheric deposition is estimated to be substantially greater than
other external sources and will continue to contribute nutrients to the lake for many years. More
importantly the cycle from sediment nutrients to water column nutrients will continue unabated
until benthic primary production increases. A more holistic biomanipulation approach is required
to circumvent the effects of nutrient loads that maintain water column primary productivity in the
lake.
We have already shown in several of our reports, literature reviews, and our experience working
on Utah Lake that its biological integrity is severely impaired due to loss of native fishes,
mollusks, and littoral zone macrophytes, as well as introduction of numerous exotic fishes.
Historically, the native flora and fauna assisted in maintaining a balance between water column
and benthic primary production prior to their demise. Restoration of the native macrophytes,
mollusks, and a balanced fish assemblage can expedite and help insure the transition.
Mollusks
Bivalves, clams and mussels
The primary contribution of filter feeding bivalves is to filter phytoplankton and increase water
clarity. Bivalves may selectively feed on certain phytoplankton taxa and alter the phytoplankton
assemblage relative abundances (Richards 2018). Long stranded mucilaginous algae are less
palatable to bivalves; however, they can filter these types of algae and deposit into the sediments
as pseudofeces (Richards 2018). Bivalves will also stabilize the substrate and provide habitat for
other organisms, just two of their many ecosystem services often overlooked by non-
malacologists.
Gastropods, Snails and the Mutualistic Positive Feedback Loop
Most freshwater gastropods (snails) graze benthic periphyton and epiphytes growing on
macrophytes and subsequently increase periphytic/epiphytic primary production. It is well
known that snail grazing increases periphytic primary production. Increases in periphytic
primary production demand for water column nutrients competes with phytoplankton primary
production demand for nutrients and increases water clarity by reducing phytoplankton density.
Gastropod excretion directly adds nutrients to the water column that can promote phytoplankton

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production that in turn can increase filter feeding by bivalves. Increased bivalve filter feeding
increases water clarity completing what is known as a mutualistic positive feedback loop and has
been documented by Richards et al. (2020) to occur in nutrient rich sheetflow wetlands of
Farmington Bay, Great Salt Lake although the primary grazers/filter feeders were chironomid
larvae, not mollusks.
See Richards (2017) for more life history, ecological and distribution patterns of mollusks in
Utah Lake drainage and their importance to transition from water column to benthic primary
production.
Macrophytes
Macrophytes, emergent aquatic vegetation (EAV) and submerged aquatic vegetation (SAV) are
critical components of healthy lake ecosystems, particularly shallow lakes (Scheffer 1998). They
provide sediment stabilization, nutrient transfer and cycling, substrate for epiphytes that in turn
provide food resources for secondary consumers such as gastropods, multilevel habitat structure
for juvenile fishes, and security for zooplankton grazers, improve water clarity, etc. Historically,
Utah Lake supported robust emergent aquatic vegetation (EAV) and submerged aquatic
vegetation (SAV) plant communities which were first documented by Cottam (1926) and later by
Brotherson (1981). The SAV communities were once abundant at Utah Lake but are now largely
non-existent and have been since at least 1926 (Cottam 1926), yet EAV communities are still
thriving in many sections of Utah Lake, particularly places such as Powell Slough. We consider
reestablishing macrophytes within the littoral zone to be of the most important biomanipulation
strategies for improvement of Utah Lake’s ecological health and holistically restoring the broken
pieces of its ecosystem function including its transition to a benthic primary production
dominated state.
Metrics
We have initiated a provisional Utah Lake Multimetric Index of Biological Integrity (MIBI) to
help managers better monitor changes in the lake’s health (Richards and Miller 2019c). Some of
the metrics listed below have already been included in our MIBI and are directly relevant to
changes in primary production from water column to benthic. The new additions will be added to
our MIBI after further refinement.
Light attenuation
The simplest and effective metric to measure changes in primary production from water column
to benthic is measuring photosynthetic active radiation (PAR), the light available for primary
production at all wavelengths of the visible spectrum (Kelble et al. 2005). Traditionally light
limitation for aquatic algal growth when light intensity is 1% of surface irradiance (Sverdrup et
al. 1954, Kelble et al. 2005, Kirk 2011). Two methods are often used, Secchi Disk depth and
quanta meters. Secchi Disks are inexpensive (< $70) but need to incorporate nonlinear models to
estimate PAR (Padial and Thomaz 2008), whereas quanta meters are expensive (several
thousand dollars) and directly record PAR.
The worldwide used Secchi Disk depth index of 1.7 does not seem to be accurate and can be as
much as 2.26 (Padial and Thomaz 2008). The nonlinear model for Secchi Disk depth index
developed by Padial and Thomaz (2008) that we will use is:

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k = 2.00 x SD-0.76
where k is the light attenuation coefficient.
PAR varies spatially and temporally in Utah Lake and can change hourly depending on the angle
of the sun and wave action. A robust dataset where and when PAR = 1% in Utah Lake needs to
be generated that can be used to compare current PAR values to future changes anticipating that
PAR will increase during the transition from water column primary productivity to benthic
primary productivity.
Phytoplankton density/diversity
Phytoplankton assemblages are expected to change during and after transition to benthic
primary production. The phytoplankton metrics in Richards and Miller (2019c) will be able
to monitor these changes.
Benthic algae density/diversity
Similar to phytoplankton density/diversity metric except they are expected to improve.
Water column vs. benthic primary production
TBD
Phytoplankton vs periphyton ratio
TBD
Mollusk densities
Focus should be on native fingernail clams (Family Sphaeriidae), Asian clam, Corbicula
fluminea, and native Physa sp. (snail) because C. fluminea and Physa sp. are already present
at low densities in Utah Lake and fingernail clams may be the first native bivalve to increase
in density.
Mollusk diversity
Mollusk diversity is expected to increase during and after transition from water column to
benthic primary productivity.
Macrophyte density and diversity
Macrophyte assemblages are expected to change during and after transition to benthic
primary production. The macrophyte metrics in Richards and Miller (2019c) will be able to
monitor these changes. Additional metrics may be required.
Benthic macroinvertebrate density/diversity
Benthic macroinvertebrate assemblages are expected to change during and after transition to
benthic primary production. The metrics in Richards and Miller (2019c) will be able to
monitor these changes.

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Zooplankton density/diversity
Zooplankton assemblages are expected to change during and after transition to benthic
primary production. The zooplankton metrics in Richards and Miller (2019c) will be able to
monitor these changes.
Littoral zone fish density/diversity
Focus on fish species that rely on littoral zone macrophytes including most juvenile stages.
Additional metrics will be required.
Literature Cited
Adey, W., Luckett, C. & Jensen, K. 1993. Phosphorus removal from natural waters using controlled algal
production. Restor. Ecol. 1: 29–39.
Brotherson, J. D. 1981.Aquatic and semiaquatic vegetation of Utah Lake and its bays. Great Basin
Naturalist Memoirs, pp. 68-84.
Cottam, W. P.1926. An ecological study of the flora of Utah Lake," University of Chicago.
Dodds, W.D. 2003. The role of periphyton in phosphorus retention in shallow freshwater aquatic systems.
J. Phycol. 39: 840-849.
Dokulil, M.T. and K. Teubner. 2000. Cyanobacterial dominance in lakes. Hydrobiologia 438: 1-12.
DROPPO I.G., ROSS N., SKAFEL M. & LISS S.N. 2007. Biostabilisation of cohesive sediment beds in a
freshwater wave-dominated environment. Limnology and Oceanography 52: 577–589. Forbes,
S.A. 1925 (1887). The lake as a microcosm. Bulletin of the Illinois Natural History Survey.
15:537-550.
Kelble, C.R., Ortner, P.B., Hitchcock, G.L., and J.N. Boyer. 2005. Attenuation of Photosynthetically
Available Radiation (PAR) in Florida Bay: Potential for Light Limitation of Primary Producers.
Estuaries 28(4): 560-571.
Kirk, J.T. 2011. Light and photosynthesis in aquatic ecosystems. Third edition. Cambridge University
Press.
Lindeman, R.L. 1942. The trophic-dynamic aspect of ecology. Ecology. 23:399-418.
MOULTEN T.P., DE SOUZA M.L., SILVEIRA R.M.L. & KRSULOVIC F.E.M. 2004. Effects of
ephemeropterans and shrimps on periphyton and sediments in a coastal stream (Atlantic Forest,
Rio De Janeiro, Brazil). Journal of the North American Benthological Society 23: 868–881.
Padial, A. A. and S. M. Thomaz. 2008. Prediction of the light attenuation coefficient through the Secchi
disk depth: empirical modeling in two large Neotropical ecosystems. Limnology 9: 143-151.
POULICKOVA, A. P. HASLER, M. LYSAKOVA AND B. SPEARS. 2008. The ecology of freshwater
epipelic algae: an update. Phycologia 47: 437–450. DOI: 10.2216/07-59.1.

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Richards, D.C. 2017. Native Unionoida Surveys, Distribution, and Metapopulation Dynamics in the
Jordan River-Utah Lake Drainage, UT. Report to Wasatch Front Water Quality Council, Salt Lake
City, UT. OreoHelix Consulting, Vineyard, UT.
Richards, D.C. 2018. A snail, a clam, and the River Jordan: A revealing novel. Technical Report to
Report to Wasatch Front Water Quality Council, Salt Lake City, UT. OreoHelix Consulting,
Vineyard, UT.
Richards, D. C. and T. Miller. 2017. A preliminary analysis of Utah Lake’s unique foodweb with a focus
on the role of nutrients, phytoplankton, zooplankton, and benthic invertebrates on HABs. Utah
Lake Research 2016. Progress Report. Wasatch Front Water Quality Council, Salt Lake City, UT.
OreoHelix Consulting, Vineyard, UT.
Richards, D. C. and T. Miller. 2019a. Utah Lake Research 2017-2018: Progress Report: Continued
analysis of Utah Lake’s unique foodweb with a focus on the role of nutrients, phytoplankton,
zooplankton, and benthic invertebrates on cyanoHABs. Chapter 1: Phytoplankton Assemblages.
Submitted to Wasatch Front Water Quality Council, Salt Lake City, UT. OreoHelix Consulting,
Vineyard, UT.
Richards, D.C. and T. Miller. 2019b. Factors Effecting the Ecological Health and Integrity of Utah Lake
with a Focus on the Relationships between Water Column Regulators, Benthic Ecosystem
Engineers, and CyanoHABs. Progress Report to Wasatch Front Water Quality Council. Salt Lake
City, UT.
Richards, D.C. and T. Miller. 2019c. A Provisional Multi-Metric Index of Biological Integrity (MIBI) to
Assess Water Quality in Utah Lake centered on Regulatory Directives. Draft Technical Report to
Wasatch Front Water Quality Council, Salt Lake City, UT. OreoHelix Ecological, Vineyard, UT.
Richards, D.C., Miller, T.G., Finley, H., Gaichuk, I., Ashurst-McGee, L., and F. Fluckiger. 2020. Ecology
and food web dynamics of an effluent dominated wetland, Great Salt Lake, UT. Progress Report
to North Davis Sewer District, Syracuse, UT. OreoHelix Ecological, Vineyard, UT and Wasatch
Front Water Quality Council, Salt Lake City, UT.
Scheffer, M. 1998. Ecology of Shallow Lakes. Kluwer Academics Publishers.
Scheffer, M., S. Carpenter, J. A. Foley, C. Folke, and B. Walker. 2001.Catastrophic shifts in ecosystems.
Nature. Vol. 413. 591-596.
Scheffer, M., S. H. Hosper, M. L. Meijer, B. Moss and E. Jeppesen, 1993. Alternative equilibria in
shallow lakes. Trends in Ecology and Evolution 8: 275–279.
Scheffer, M., Rinaldi, S., Gragnani, A., Mur, L.R., and E. H. Van Nes. 1997. On the dominance of
filamentous cyanobacteria in shallow, turbid lakes. Ecology, 78(1):272–282.
Smith, V. H., E. Willén & B. Karlsson, 1987. Predicting the summer peak biomass of four species of
blue-green algae (Cyanophyta/Cyanobacteria) in Swedish lakes. Wat. Res. Bull. 23: 397–402.
SPEARS B.M., FUNNELL J., SAUNDERS J. & PATERSON D.M. 2007. On the boundaries: sediment
stability measurements across aquatic ecosystems. In: Sediment dynamics and pollutant mobility

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in rivers: An interdisciplinary approach (Ed. by B. Westrich & U. Fostner), pp. 68–78. Springer,
Germany.
SVERDRUP, H. U., M. W. JOHNSON, AND R. H. FLEMING. 1954. The Oceans: Their Physics,
Chemistry, and General Biology. Prentice Hall, Englewood Hills, New Jersey.
Vadeboncoeur, Y. Vander Zanden, J. and D.M. Lodge. 2002. Putting the lake back together:
Reintegrating benthic pathways into lake food web models. BioScience 52: 44–55.
Vadeboncoeur, Y. et al., 2003. From Greenland to green lakes: Cultural eutrophication and the loss of
benthic pathways in lakes. Limnol. Oceanogr. 48(4): 1408-1418.
Vadeboncoeur, Y., Peterson, G, Vander Zanden, J., and J. Kalff. 2008. Benthic algal production across
lake size gradients: interactions among morphometry, nutrients, and light. Ecology 89(9): 2542-
2552.
VELASCO J., MILLAN A., VIDAL-ABARCA M.R., SUAREZ M.L., GUERRERO C. & ORTEGA M.
2003. Macrophytic, eipipelic, and epilithic primary production in a semiarid Mediterranean
stream. Freshwater Biology 48: 1408–1420.