Species-specific algal responses to zooplankton: experimental and field observations in three nutrient-limited lakes

Elser, James J.; Goff, Nancy C.; MacKay, Neil A.; Amand, Ann L. St.; Elser, Monica; Carpenter, Stephen R.

doi:10.1093/plankt/9.4.699

Cited by 55 publications

(41 citation statements)

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“…Positive relationship among chl a, phaeopigment and zooplankton population can be explained by a positive and selective effects of grazing by zooplankton. Positive effects of grazing results increased growth rates of phytoplankton via nutrient regeneration that could potentially offset the negative effects of grazing mortality (Elser et al 1987). At the time of grazing a degree of size and selectivity also exists among the grazing zooplankton.…”

Section: Resultsmentioning

confidence: 99%

Seasonality of Phytoplankton productivity of the river Turag of Dhaka in relation to its water quality

Khondker

Abed

2014

Bangladesh J. Bot.

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A total of 16 water quality parameters together with the phytoplankton biomass as chlorophyll a and potential primary productivity of the river Turag of Bangladesh were measured for one year (July 1994 -June 1995. Potential primary productivity ranged from 6.22 -199.7 µgC/l/hr which showed a closer peak with total phytoplankton. Chlorophyll a, phosphate-phosphorus and nitrate-nitrogen concentration of the river ranged from 1. 84 -162.8, 30.28 -796.54 and 27.02 -905.04 µg/l, respectively. A decrease in the mean concentration of these parameters in monsoon was seen compared to their high concentration in pre-monsoon period, which however, increased again in post-monsoon and winter. In the one hand, strong positive correlation was observed between primary productivity and chl a, on the other hand, chl a showed strong positive correlation with phosphate-phosphorus and nitrate nitrogen. Significant negative correlation between dissolved oxygen (DO) and phosphate-phosphorus indicates the eutrophic nature of the river. This effect was minimized in monsoon. Concentration of phosphate-phosphorus, nitrate-nitrogen and chl a remained high in pre-monsoon period but reduced by 90, 87 and 97%, respectively in monsoon. Besides, DO recovered 90% in monsoon compared to its pre-monsoon concentration. Within a span of one and a half decade, the concentration of PO 4 -P and NO 3 -N in the water has increased 4 -and 32-fold, respectively.

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Section: Resultsmentioning

confidence: 99%

Seasonality of Phytoplankton productivity of the river Turag of Dhaka in relation to its water quality

Khondker

Abed

2014

Bangladesh J. Bot.

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“…Thus, each summer experiment consisted of either an ambient or a Daphnia gradient, For spring experiments, we collected D. pulicaria from nearby Lake Monona. We collected Daphnia the evening before an experiment and held the animals at Lake Mendota epilimnetic temperatures overnight (Elser et al 1987). By collecting Daphnia with a coarsemesh net, we ensured that we did not add unwanted smaller zooplankton to containers along with Daphnia.…”

Section: Methodsmentioning

confidence: 99%

Seasonal patterns of grazing and nutrient limitation of phytoplankton in a eutrophic lake

Vanni

Temte

1990

Limnology & Oceanography

141

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Observations and experiments on zooplankton grazing and nutrient (N and P) limitation of phytoplankton of Lake Mendota, Wisconsin, revealed that the relative strength of the two factors varied markedly during the seasonal succession of phytoplankton. Furthermore, seasonal changes in grazing and nutrient limitation were caused not only by seasonal changes in zooplankton community structure and nutrient availability but also by changes in phytoplankton community structure, which led to changes in edibility to zooplankton. The spring phytoplankton bloom of diatoms and small flagellates was highly vulnerable to grazing by both cyclopoid copepods and Duphnia, although Daphnia had a much stronger effect. Increased Duphnia grazing in late spring resulted in low phytoplankton biomass (the clear-water period) and a phytoplankton community dominated by colonial green algae-taxa vulnerable to grazing by Daphnia but not other zooplankton. Nutrients (N and P) did not limit phytoplankton growth during the spring bloom or the clear-water period. After the clear-water period, the summer phytoplankton community was dominated by blue-greens and Ceratium. Grazing effects by both Daphnia and copepods were low in summer, while nutrient limitation (both N and P) became severe. Reduced grazing impacts in summer may have resulted from prior intense grazing impacts, which led to dominance of grazing-resistant taxa. These results suggest that seasonal variation in the strength of grazing and nutrient controls in eutrophic lakes results from changes in zooplankton biomass and community structure, nutrient availability, and phytoplankton community structure interacting to determine phytoplankton seasonal succession.Freshwater phytoplankton communities often undergo pronounced seasonal succession (Reynolds 1984). The successional pattern in a lake is fairly repeatable among years, and patterns among lakes are somewhat predictable according to trophic status (e.g. Reynolds 1984;Sommer et al. 1986). Understanding the mechanisms causing seasonal succession and its consequences for other trophic levels, however, is still limited ' Present address:

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“…However, ~1 could increase in the grazer treatment compared to the grazer-free control. This effect is usually ascribed to nutrient excretion (Sterner 1985;Elser et al 1988), but other explanations are also possible, especially in dense biofilms as studied here. Such explanaAcknowledgments Technical assistance by Cordula Stielau and Britta Johannsen is gratefully acknowledged.…”

Section: Theorymentioning

confidence: 57%

“…Experiments of that type fall into two categories. If grazers clearly differ in size from their food organisms or can be added individually, grazer densities can be manipulated without manipulating the density of food organisms (Lehman and Sandgren 1985;Sterner 1986;Elser et al 1988). If grazers cannot be well separated from their food, the entire plankton community is diluted by filtered seawater or lake water (Landry and Hasset 1982;Andersen et al 1991).…”

Section: Discussionmentioning

confidence: 99%

Selectivity of Idothea chelipes (Crustacea: Isopoda) grazing on benthic microalgae

Sommer¹

1997

Limnology & Oceanography

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Periphyton grazing by the marine isopod Idothea chelipes was studied by exposing periphyton grown on glass slides to a gradient of grazer densities. An analysis of the algal growth rates and their relationships to grazer density revealed two groups of algae. The unicellular diatoms Licmophora ehrenbergii, Fragilaria tabulata, Navicula spp., Cocconeis costata, and the green alga Ulothrix implexa had high maximal gl'owth rates (0.90-1.47 d-l) and suffered high grazing losses (0.41-0.68 d--l per grazer ind.). The tube dwelling diatc,m Amphipleura rutilans and the cyanobacteria Lyngbya confervoides and Spirulina subsalsa had low maximal growth rates (0.38-0.81 d-l) and suffered only moderate grazing losses (0.10-0.27 d-l per grazer ind.). The species of the first group seemed to be less strongly resource limited than did the species of the second group. Grazing by I. chelipes has the potential to drive succession from the well-edible to the less edible periphyton species.Grazing on marine benthic microalgae has received much less attention than has grazing on phytoplankton. Most studies have concentrated on bulk effects on biomass, but not on selectivity, between algal species. Most selectivity studies in marine benthic herbivory have concentrated on selectivity between macrophytes and microalgae (Hawkins and Hartnoll 1983;Peduzzi 1987), cleaning of macrophytes from their microalgal epiphytes (Neckles et al. 1993), or selectivity between macrophytes (Schaffelke et al. 1995). Herein, I present results of in situ experiments where periphyton grown on artificial substrates have been exposed to gradients of Idothea chelipes densities. Its congener Idiothea baltica is an omnivore with a broad food spectrum that includes benthic microalgae, filamentous algae, macroalgae, detritus, animals, and even occasional cannibalism. Despite its omnivory, I. baltica is quite selective within food categories. Among macroalgae there is a clear preference of Fucus vesiculosus over Fucus evanescens (Schaffelke et al. 1995); within filamentous algae, germlings of the green alga Enteromorpha spp. are preferred over germlings of the brown alga Pilayella litoralis while adult P. litoralis are preferred over adult Enteromorpha (Schramm et al. 1996). In the western Baltic Sea, Zdiothea spp. are among the most important benthic herbivores. TheoryIn the absence of guts analysis or direct observations of ingestion, feeding selectivity can best be analyzed by comparing mortality rates due to grazing (grazing rate, 7) between food species (Sterner 1989). When ignoring other sources of mortality, y can be calculated from the gross growth rate (p) and the net growth rate (r) in the presence of a grazer (y = p -r). However, ~1 could increase in the grazer treatment compared to the grazer-free control. This effect is usually ascribed to nutrient excretion (Sterner 1985;Elser et al. 1988), but other explanations are also possible, especially in dense biofilms as studied here. Such explanaAcknowledgments

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Species-specific algal responses to zooplankton: experimental and field observations in three nutrient-limited lakes

Cited by 55 publications

References 0 publications

Seasonality of Phytoplankton productivity of the river Turag of Dhaka in relation to its water quality

Seasonality of Phytoplankton productivity of the river Turag of Dhaka in relation to its water quality

Seasonal patterns of grazing and nutrient limitation of phytoplankton in a eutrophic lake

Selectivity of Idothea chelipes (Crustacea: Isopoda) grazing on benthic microalgae

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