Multiyear oscillations in depth affect water quality in Lake Apopka

Havens, Karl E.; Ji, Gaohua

doi:10.1080/20442041.2018.1428429

Cited by 17 publications

(18 citation statements)

References 27 publications

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“…During droughts, lower water levels with highly concentrated suspended solids may actually worsen conditions for macrophytes. These effects, which have also been observed in shallow, subtropical Lake Apopka [104], are, however, not straightforward, as they are very much affected by the hydraulic response of the system (i.e., lake retention time) to hydro-meteorological factors, such as the intensity, duration and frequency of flood-producing extreme rainfall events, and the characteristics of the basin that determine its response in terms of erosion and run-off, which ultimately increase sediment input. As previously explained, the hydraulic regime, meteorological patterns and sediment dynamics are all changing in Ypacaraí Lake because of major engineering interventions, land use and climate change.…”

Section: Opportunities For Researchsupporting

confidence: 59%

Eutrophication, Research and Management History of the Shallow Ypacaraí Lake (Paraguay)

et al. 2018

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Ypacaraí Lake is the most renowned lake in landlocked Paraguay and a major source of drinking and irrigation water for neighbouring towns. Beyond its socioeconomic and cultural significance, it has great ecological importance, supporting a rich biodiversity. Rapid growth of human presence and activities within its basin has led to its environmental degradation, a heartfelt matter of high political concern that compels intervention. Here, by reconstructing the history of scientific and management-oriented research on this system, we provide a comprehensive assessment of current knowledge and practice to which we contribute our recent, novel findings. An upward trend in total phosphorus concentration confirms ongoing eutrophication of an already eutrophic system, evidenced by consistently high values of trophic state indices. Downward trends in water transparency and chlorophyll-a concentration support the hypothesis that primary production in this lake is fundamentally light limited. Statistical and other analyses suggest high sensitivity of the system to hydraulic, hydro-morphological and hydro-meteorological alterations arising, respectively, from engineering interventions, land use and climate change. By discussing knowledge gaps, opportunities for research and challenges for management and restoration, we argue that this case

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Section: Opportunities For Researchsupporting

confidence: 59%

Eutrophication, Research and Management History of the Shallow Ypacaraí Lake (Paraguay)

et al. 2018

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“…We reached similar conclusions after studying the relationship between cyanobacteria blooms and water depth in seven central Florida lakes [7]. We recently found that in one of Florida's largest lakes, Lake Apopka, multi-year oscillations in depth were the major factor affecting TP, TN, Chl-a, and Secchi disk transparency (SD) in this lake over the period of time from 1999 to 2016 [8].…”

Section: Introductionmentioning

confidence: 53%

“…Chl-a concentrations increased, and SD declined. As we discussed previously [8], it is likely that during shallow depth periods, the reduced lake volume concentrated nutrients, enhanced the relative effects nutrient mobilization by benthivorous fish, and resulted in a loss of cladoceran zooplankton due to intensified fish predation. Periods of extreme shallow depth also coincided with stagnation (little or no water movement into or out of the lake), and this further supports the development of cyanobacteria blooms that happened to coincide with the elevated TP and TN in the water column [7].…”

Section: Discussionmentioning

confidence: 85%

“…Lake rehabilitation programs have included: purchasing a large area of former agricultural land north of the lake to reduce P loads, restoring it to wetland habitat [14], constructing a large wetland treatment system to filter algal cells from the lake water [15], and removing large quantities of benthivorous fish from the lake by commercial gill netting after documenting that their activities contribute to the high internal P loading [11,16,17]. Our study from 1999 to 2016 indicated that there were no significant downward trends in TP, TN, Chl-a and no significant increase in SD [8] despite the ongoing lake restoration actions. However, the intent of that study was only to document the effects of three successive shallow depth events on water quality in a case study, and not to evaluate the efficacy of the Lake Apopka restoration program.…”

Section: Introductionmentioning

confidence: 87%

“…The period of record is from August 1985, when sampling began, to August 2018, the most recently available data. A subset of this same dataset was used by Havens and Ji [8] in the previous assessment of the effects of rainfall and water depth on this lake. Sampling in each month was done in north, south, and central sites ( Figure 1).…”

Section: Samplingmentioning

confidence: 99%

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Periods of Extreme Shallow Depth Hinder but Do Not Stop Long-Term Improvements of Water Quality in Lake Apopka, Florida (USA)

Havens

2019

Water

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We recently documented that during times of extreme shallow depth, there are severe effects on the water quality of one of the largest shallow lakes in the southeastern USA—Lake Apopka. During those times, total phosphorus (TP), total nitrogen (TN), chlorophyll-a (Chl-a) and toxic cyanobacteria blooms increase, and Secchi transparency (SD) declines. The lake recovers when water levels rise in subsequent years. In this paper, we determined whether extreme shallow depth events, particularly when they re-occur frequently, can stop the long-term recovery of a shallow eutrophic lake undergoing nutrient reduction programs. Apopka is an ideal location for this case study because the State of Florida has spent over 200 million USD in order to reduce the inputs of P to the lake, to build large filter marshes to treat the water, and to remove large quantities of benthivorous fish that contribute to internal P loading. We obtained data from 1985 to 2018, a period that had relatively stable water levels for nearly 15 years, and then three successive periods of extreme shallow depth, and we examined the long-term trends in TP, TN, Chl-a, and SD. There were significant decreasing trends in all of these water quality variables, and even though water quality deteriorated during periods of extreme shallow depth, and reduced the slope of the long-term trends, it did not stop the recovery. However, in the future, if climate change leads to more frequent shallow depth events, which in lakes such as Apopka, result in the concentration of water and nutrients, it is unclear whether the resilience we document here will continue, vs. the lake not responding to further nutrient input reductions.

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Water depth influences algal distribution and productivity in shallow agricultural lakes

2021

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Agricultural activity can alter water quality and quantity resulting in lakes facing increasing interactive stressors including eutrophication, suspended sediment and water withdrawal. This study examined the relationships between water depth, water quality and algae in shallow agricultural lakes in the lower Mississippi River Basin (LMRB) to assess how lake depth influences algal structure and function, focusing on factors that typically regulate growth, that is, light, temperature and nutrients. Lake water and sediment cores were collected in shallow (mean = 0.8 m) and deep (mean = 1.7 m) locations in three lakes seasonally for 1 year. Additionally, interactive effects of light and temperature on algal growth were investigated through a laboratory experiment to determine the relative importance of each in regulating algal biomass and net oxygen production. In these shallow, turbid, eutrophic lakes, deeper water had lower nutrient concentrations and temperature across all seasons and clearer water in the summer. Shallow areas had more phytoplankton and periphyton. Water temperature had a stronger correlation than light with both phytoplankton and periphyton biomass. Algal biomass generally decreased with increasing water temperature, but biomass was better predicted by increasing nitrogen availability, and productivity declined with greater phosphorus availability. Water depth was therefore likely influencing different locations of the same lake towards different algal stable states. Mitigating excess algal production is an important goal towards limiting hypoxic conditions in the LMRB, and increasing water storage could help moderate temperature, nutrients and turbidity effects that contribute to algal blooms in lakes receiving agricultural runoff.

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Multiyear oscillations in depth affect water quality in Lake Apopka

Cited by 17 publications

References 27 publications

Eutrophication, Research and Management History of the Shallow Ypacaraí Lake (Paraguay)

Eutrophication, Research and Management History of the Shallow Ypacaraí Lake (Paraguay)

Periods of Extreme Shallow Depth Hinder but Do Not Stop Long-Term Improvements of Water Quality in Lake Apopka, Florida (USA)

Water depth influences algal distribution and productivity in shallow agricultural lakes

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