Journal ArticleDOI
The Midsummer Dynamics of Two Daphnia Species in Wintergreen Lake, Michigan
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TLDR
Differences in body size, ephippial production and habitat preferences between the 2 species are consistent with the hypothesis that planktivory is a strong selective force in their evolution.Abstract:
During 1976, midsummer reductions in densities of Daphnia pulicaria and Daphnia galeata mendotae populations occurred in Wintergreen Lake, Michigan Previous attempts to deter- mine the causes of such declines have indicated correlations between predator populations, the pres- ence of unpalatable algae or high midsummer water temperatures, and the reduction or disappearance of the daphnid populations In this study, in situ life table experiments were performed to assess the influence of natural food and temperature conditions on population growth A weekly sampling program showed that D pulicaria was dielly concentrated, after early summer, at depths between the anaerobic hypolimnion and the warmer epilimnion, consistent with previous information indicating it to be a cold-water species However, in situ life table data showed that D pulicaria was capable of surviving in epilimnetic water up to 27C, although reproduction was greatly reduced for a 6-day period in mid-July This reduction in reproduction appeared to be the result of an interaction of high temperatures, declining standing crops of small algae and increasing amounts of Anabaena, Ceratium and Volvox Daphnia galeata mendotae did not show any adverse response to these mid-July algae-temperature conditions Analysis of predator gut contents suggested that both daphnids were heavily preyed upon by bluegills (Lepomis macrochirus) Shifts in the size structure of the daphnid populations were also consistent with intense size-selective predation by bluegills, as was the tendency for the age distri- bution of parthenogenic eggs to become skewed to younger eggs as the midsummer decline proceeded Differences in body size, ephippial production and habitat preferences between the 2 species are also consistent with the hypothesis that planktivory is a strong selective force in their evolutionread more
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Journal ArticleDOI
The relationship in lake communities between primary productivity and species richness
TL;DR: This study investigated the relationship between the primary productivity of lake ecosystems and the number of species for lacustrine phytoplankton, rotifers, cladocerans, copepods, macrophytes, and fish, and compared the effects of short- and long-term whole-lake nutrient addition on primary productivity and planktonic species richness.
Book ChapterDOI
The Role of Predation in Zooplankton Succession
TL;DR: For the last two decades predation has been considered to be a major driving force in shaping zooplankton communities and in determining their density and structure as mentioned in this paper, and predation was considered the major factor responsible for successional events.
Book ChapterDOI
Why do cladocerans fail to control algal blooms
TL;DR: In the absence of planktivorous fish, large-bodied cladocerans effectively control the abundance of algae of a broad size spectrum as discussed by the authors, although difficult to handle and of poor nutritional value, filamentous algae can also be utilized by Daphnia and prevented from population increase.
Journal ArticleDOI
Cyclic and Stable Populations: Plankton as Paradigm
TL;DR: The hypothesis is that the presence or absence of cycles is determined by the relationships between time delays in Daphnia and other rates in the interacting populations, and this findings support a basic premise of most mathematical models in ecology.
Journal ArticleDOI
Effects of experimentally induced cyanobacterial blooms on crustacean zooplankton communities
TL;DR: It is demonstrated that zooplankton communities can be negatively affected by cyanobacterial blooms and therefore the potential to use herbivory to reduce algal blooms in such eutrophic lakes appears limited.
References
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Journal ArticleDOI
The Evolution of Life History Traits: A Critique of the Theory and a Review of the Data
TL;DR: Two models which give alternative explanations for the adaptation of life history traits to stable and fluctuating environments are reviewed and tried to understand what life history data could mean in general, given the present state of knowledge.
Journal ArticleDOI
The Size-Efficiency Hypothesis and the Size Structure of Zooplankton Communities
TL;DR: The size-efficiency hypothesis is an attempt to explain the commonly observed inverse relationship between the abundances of small and of large-bodied herbivorous zooplankton in freshwater lakes.