scholarly journals Alternative Attractors of Shallow Lakes

2001 ◽  
Vol 1 ◽  
pp. 254-263 ◽  
Author(s):  
Marten Scheffer
Keyword(s):  
Shallow Lakes ◽  
Algal Blooms ◽  
Sediment Resuspension ◽  
Fish Predation ◽  
Fish Stock ◽  
Nutrient Loads ◽  
High Concentration ◽  
Temporary Reduction ◽  
Light Levels ◽  
Turbid State

Ponds and shallow lakes can be very clear with abundant submerged plants, or very turbid due to a high concentration of phytoplankton and suspended sediment particles. These strongly contrasting ecosystem states have been found to represent alternative attractors with distinct stabilizing feedback mechanisms. In the turbid state, the development of submerged vegetation is prevented by low underwater light levels. The unprotected sediment frequently is resuspended by wave action and by fish searching for food causing a further decrease of transparency. Since there are no plants that could serve as refuges, zooplankton is grazed down by fish to densities insufficient to control algal blooms. In contrast, the clear state in eutrophic shallow lakes is dominated by aquatic macrophytes. The submerged macrophytes prevent sediment resuspension, take up nutrients from the water, and provide a refuge for zooplankton against fish predation. These processes buffer the impacts of increased nutrient loads until they become too high. Consequently, the response of shallow lakes to eutrophication tends to be catastrophic rather than smooth, and various lakes switch back and forth abruptly between a clear and a turbid state repeatedly without obvious external forcing. Importantly, a switch from a turbid to a stable clear state often can be invoked by means of biomanipulation in the form of a temporary reduction of the fish stock.

scholarly journals Possible effects of climate change on ecological functioning of shallow lakes, Lake Loenderveen as a case study

2007 ◽  
Vol 38 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Sebastiaan Schep ◽  
Gerard Ter Heerdt ◽  
Jan Janse ◽  
Maarten Ouboter
Keyword(s):  
Climate Change ◽  
Shallow Lakes ◽  
Ecological Status ◽  
Nutrient Load ◽  
Nutrient Loads ◽  
Clear Water ◽  
Turbid State ◽  
Good Ecological Status ◽  
Ecological Functioning

Possible effects of climate change on ecological functioning of shallow lakes, Lake Loenderveen as a case study The European Water Framework Directive (WFD) requires all inland and coastal waters to reach "good ecological status" by 2015. The good ecological status of shallow lakes can be characterised by clear water dominated by submerged vegetation. The ecological response of shallow lakes on nutrients largely depends on morphological and hydrological features, such as water depth, retention time, water level fluctuations, bottom type, fetch etc. These features determine the "critical nutrient load" of a lake. When the actual nutrient load of a lake is higher than the critical nutrient load, the ecological quality of this lake will deteriorate, resulting in a turbid state dominated by algae. Climate change might lead to changes in both environmental factors and ecosystem response. This certainly will have an effect on the ecological status. As an illustration the results of a multidiscipline study of a shallow peaty lake (Loenderveen) are presented, including hydrology, geochemistry and ecology. Ground- and surface water flows, nutrient dynamics and ecosystem functioning have been studied culminating in an application of the ecological model of the lake (PCLake). Future scenarios were implemented through changing precipitation, evaporation and temperature. Climate change will lead to higher nutrient loads and lower critical nutrient loads. As a consequence lakes shift easier from clear water to a turbid state.

Water Quality Trends in Hamilton Harbour: 1987 to 1995

1996 ◽  
Vol 31 (3) ◽  
pp. 473-484 ◽  
Author(s):  
Murray N. Charlton ◽  
Robin Le Sage
Keyword(s):  
Algal Blooms ◽  
Action Plan ◽  
Secchi Depth ◽  
Water Clarity ◽  
Nutrient Loads ◽  
Hamilton Harbour ◽  
Near Shore ◽  
The Media ◽  
Park Area ◽  
Water Quality Trends

Abstract A series of water samples and Secchi depth measurements were conducted in Hamilton Harbour between 1987 and 1995. The data indicate little recent improvement in the harbour generally. Detection of real improvements may require high frequency sampling and a more extensive sample grid once a cause for improvement is in place. Some measures, such as chlorophyll and Secchi depth, approach RAP initial goals sometimes during recent years, but algal blooms still occur, which prevent attainment of satisfactory average conditions. The cause of aesthetic improvements in water clarity reported in the media was investigated with sampling along an inshore-offshore transect and intense Secchi measurements in the LaSalle Park area. The data are consistent with a transient clarifying effect of zebra mussels on structures near shore. The need to reduce nutrient loads as recommended in the Remedial Action Plan continues.

How climate change and eutrophication interact with microplastic pollution and sediment resuspension in shallow lakes: A review

2020 ◽  
Vol 705 ◽  
pp. 135979 ◽  
Author(s):  
Yafei Zhang ◽  
Jie Liang ◽  
Guangming Zeng ◽  
Wangwang Tang ◽  
Yue Lu ◽  
...  
Keyword(s):  
Climate Change ◽  
Shallow Lakes ◽  
Sediment Resuspension

Assessment of Phytoplankton Nutrient Limitation in Productive Waters: Application of Dilution Bioassays

1993 ◽  
Vol 50 (10) ◽  
pp. 2208-2221 ◽  
Author(s):  
Hunter J. Carrick ◽  
Claire L. Schelske ◽  
Frederick J. Aldridge ◽  
Michael F. Coveney
Keyword(s):  
Large Fraction ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Nutrient Reduction ◽  
High Concentration ◽  
Phytoplankton Assemblages ◽  
Lake Apopka ◽  
P Limitation ◽  
Management Scheme ◽  
Total P

Excessive nutrient loads to aquatic systems can complicate otherwise predictable relationships between nutrient concentrations and phytoplankton biomass. We conducted six bioassays on surface phytoplankton assemblages collected from productive Lake Apopka, Florida, to measure the effect of nutrient reduction on phytoplankton growth and nutritional state. Lake water was mixed with one of three diluents to create a gradient of ambient nutrient concentrations; nitrogen (N) and phosphorus (P) limitation at each level of dilution was evaluated in a 2 × 2 factorial design. While the addition of N clearly increased the growth of phytoplankton in undiluted Lake Apopka water, the phytoplankton became more P limited with the reduction of particles (30–60% dilution). Regression of algal yields onto total P concentrations from our bottle experiments indicated that an 8 μg∙L−1 change in P leads to only a 1 μg∙L−1 change in chlorophyll yield, probably due to the high concentration of P in the lake. Because dilution influences factors in addition to ambient nutrient concentrations, results obtained with the technique must be carefully evaluated. Despite this, reduction of particles to improve water quality may, in concept, be a reasonable management scheme in lakes where a large fraction of the nutrients is particulate.

scholarly journals Responses of food web to hypolimnetic aeration in Lake Vesijärvi

Hydrobiologia ◽  
2020 ◽  
Vol 847 (21) ◽  
pp. 4503-4523 ◽  
Author(s):  
Jukka Ruuhijärvi ◽  
Tommi Malinen ◽  
Kirsi Kuoppamäki ◽  
Pasi Ala-Opas ◽  
Mika Vinni
Keyword(s):  
Body Size ◽  
Food Web ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Perca Fluviatilis ◽  
Fish Predation ◽  
Filamentous Cyanobacteria ◽  
Low Oxygen ◽  
High Quality ◽  
Oxygen Conditions

AbstractWe studied the responses of a food web, especially fish and zooplankton, to summertime aeration, pumping of oxygen-rich epilimnetic water to the hypolimnion in Lake Vesijärvi, southern Finland. The aim of hypolimnetic aeration was to reduce internal loading of phosphorus from sediment. The population of smelt (Osmerus eperlanus L.), the main planktivore of the pelagial area, collapsed during the two 1st years of aeration due to increased temperature and low oxygen concentrations in the hypolimnion. The population recovered after the 4th year of hypolimnetic aeration, when oxygen conditions were improved. Despite elevated hypolimnetic temperature, smelt reached exceptionally high abundance, which led to a significant reduction in cladoceran body size. The density of perch (Perca fluviatilis L.) increased at first, but then decreased when the proportion of smelt and cyprinids increased. Biomasses of Daphnia decreased probably as a result of the disappearance of dark, low-oxygen deep-water refuge against fish predation and low availability of nutritionally high-quality algae. Occasionally filamentous cyanobacteria, such as turbulence tolerant Planktothrix agardhii (Gomont), were abundant, suggesting deteriorated food resources for zooplankton. The responses of food web were controversial with respect to the aim of the management, which was to prevent the occurrence of harmful algal blooms.

Wind Resuspension of Sediments in a Prairie Lake

1984 ◽  
Vol 41 (12) ◽  
pp. 1763-1767 ◽  
Author(s):  
Glenn L. Carper ◽  
Roger W. Bachmann
Keyword(s):  
Shallow Lakes ◽  
Suspended Solids ◽  
Sediment Resuspension ◽  
Wave Theory ◽  
Wind Effects ◽  
Wind Velocities ◽  
Critical Velocities ◽  
Wind Mixing

We measured levels of inorganic suspended solids in Little Wall Lake, Iowa, and concluded that sediment resuspension occurred when wind velocities exceeded critical velocities as calculated from wave theory. The percentages of the lake bed subject to resuspension for winds of given velocities were calculated, as were the percentages of time that winds of such velocities could be expected. We concluded that only a small percentage of the lake bed is subject to resuspension most of the time. The techniques to calculate wind effects and to summarize the data on frequency of wind mixing used in this study should be generally applicable to problems of sediment resuspension in other shallow lakes.

scholarly journals Cyanobacterial blooms in shallow lakes of the Iławskie Lake District

2011 ◽  
Vol 11 (2) ◽  
pp. 69-79 ◽  
Author(s):  
Ewa Dembowska
Keyword(s):  
Green Algae ◽  
Trophic Level ◽  
Shallow Lakes ◽  
Algal Blooms ◽  
Catchment Area ◽  
Cyanobacterial Blooms ◽  
Lake District ◽  
Eutrophic Lakes ◽  
Blue Green Algae ◽  
Catchment Areas

Cyanobacterial blooms in shallow lakes of the Iławskie Lake DistrictThe dominance of blue-green algae observed in many lakes is related to a high trophic level. Shallow eutrophic lakes are particularly often abundant in blue-green algae. The research on phytoplankton, the results of which are presented in this paper, was carried out between 2002 and 2005 in six lakes. These lakes differed considerably in their size and management methods applied in the catchment (drainage) area. A few types of water blooms were distinguished, which is related to the catchment area management, the intensity of mixing and the trophic level. Algal blooms of the Planktothrix type appeared in lakes situated in an open area of agricultural catchment basins. Algal blooms of the Limnothrix type were characteristic of lakes with a forest-agricultural catchment area but surrounded by high shores, which reduced the wind influence on the mixing. Sporadic mixed algal blooms were typical of lakes situated in forest catchment areas.

Seagrass responses to and recovery (?) from seven years of brown tide

1999 ◽  
Vol 5 (4) ◽  
pp. 306 ◽  
Author(s):  
C. P. Onuf
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Seagrass Meadow ◽  
Water Clarity ◽  
Brown Tide ◽  
Halodule Wrightii ◽  
Clear Water ◽  
High Concentration ◽  
Grass Meadow ◽  
Reduced Light

Most harmful algal blooms are relatively short, violent paroxysms to aquatic systems. The Texas brown tide was unique in its 7-year domination of upper Laguna Madre wherein it reduced light penetrating 1 m from 31 to 63% on an annual basis between June 1990 and May 1997. In response, seagrasses declined in biomass in deep areas for two years. Over the next three years, bare areas opened up in the deepest areas of the seagrass meadow and the outer seagrass boundary retreated landward. In the last two years of the brown tide, regression of the dominant species, Halodule wrightii, slowed and stopped, and Halophila engelmanni, a previously minor species, revegetated some areas. Subsequent to cessation of meadow retreat, water clarity improved to pre-brown tide levels, consistent with the hypothesis that regeneration of nutrients from retreating sea grass meadow may have been the source of the nutrient subsidy required to sustain the brown tide at high concentration. However, after a short interlude of clear water and Halodule recovery, a resurgence of the bloom occurred and areas of regrowth succumbed. Although human activities did not seem to be involved in initiation or persistence of the brown tide, nutrients brought in by runoff from agricultural lands may have contributed to the return of bloom conditions.

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