Lecture Goals Introduction to the major groups of zooplankton Discussion of common and distinguishing characteristics of these groups Important controls on distribution and abundance of zooplankton

Approach to Freshwater Animals Descriptions of major groups, organized taxonomically when possible Some morphology, but I will focus on life history and ecology Life History: changes experienced by an individual between birth and death that determine habitat requirements, ecology, and reproductive output Ecology: interactions among species, or between the focal species (stage) and physical habitat

What are zooplankton? Microscopic animals that float freely in the water column Very important as primary consumers – converting energy from phytoplankton to a form that can be used by larger animals Important food base for secondary consumers, including fish

Major groups of freshwater zooplankton Rotifers Cladocerans Copepods

Rotifers 50 μm – 3 mm Smallest metazoan

Taxonomy http://tolweb.org/tree/ Kingdom Phylum Class Order Family Genus Species http://tolweb.org/tree/

Rotifer Taxonomy Kingdom: Animalia Phylum: Rotifera Class Order Family Genus Species

Rotifer Diversity **High diversity in morphology

Cyclical Parthenogenesis* STRESS

Resting Eggs

Cyclical Parthenogenesis

No Molting → Cell Expansion Rotifer Life Cycle No Molting → Cell Expansion

Rotifer Colonies

Major groups of freshwater zooplankton Rotifers Cladocerans Copepods

Cladocerans 0.5 mm – 3 mm

Cladoceran Taxonomy Kingdom: Animalia Phylum: Arthropoda Class: Crustacea Orders: Cladocera Family: Daphniidae and Bosminidae Genus Species

Cladoceran Families Daphniidae Bosminidae **High diversity in morphology

Cyclical Parthenogenesis*

Cladoceran Eggs

Cladoceran Life Cycle

Cyclical Parthenogenesis

Ephippium

Cyclical Parthenogenesis

Major groups of freshwater zooplankton Rotifers Cladocerans Copepods

Copepods 1.0 mm – 8.5 mm

Copepod Taxonomy Kingdom: Animalia Phylum: Arthropoda Class: Crustacea Orders: Cyclopoida, Calanodia, Harpacticoid Family Genus Species

Copepod Orders Cyclopoid Calanoid Harpacticoid **Low diversity in morphology

Copepod Egg Sacs Cyclopoid

Copepod Egg Sacs Calanoid

Copepod Egg Sacs Harpacticoid

Copepod Life Cycle

Controls on Zooplankton Distribution and Abundance Temperature  Nutrients Physical Phactors  Phish  Phytoplankton Vertical Migration Parthenogenic ↔ Sexual Cycles Predation among Zooplankton

Controls on Zooplankton Distribution and Abundance Temperature  Nutrients Physical Phactors  Phish  Phytoplankton Vertical Migration Parthenogenic ↔ Sexual Cycles Predation among Zooplankton

Zoop Distribution and Abundance: Temperature  Nutrients

Controls on Zooplankton Distribution and Abundance Temperature  Nutrients Physical Phactors  Phish  Phytoplankton Vertical Migration Parthenogenic ↔ Sexual Cycles Predation among Zooplankton

Zoop Distribution and Abundance: Physical  Phish  Phytoplankton

Zooplankton Population Dynamics

Controls on Zooplankton Distribution and Abundance Temperature  Nutrients Physical Phactors  Phish  Phytoplankton Vertical Migration Parthenogenic ↔ Sexual Cycles Predation among Zooplankton

Zoop Distribution and Abundance: Vertical Migration Pattern Variation with stage and sex Light is proximal cue 3 main hypotheses

Vertical Migration Hypotheses: Predation

Vertical Migration Hypotheses: Food Quality

Vertical Migration Hypotheses: High Feeding Efficiency Growth and Feeding Efficiency as a Function of Temperature “Hunt warm, rest cool” High Growth Efficiency

Controls on Zooplankton Distribution and Abundance Temperature  Nutrients Physical Phactors  Phish  Phytoplankton Vertical Migration Parthenogenic ↔ Sexual Cycles Predation among Zooplankton

Zoop. Distribution and Abundance: Parthenogenic -Sexual Cycles VS.

Parthenogenic -Sexual Cycles Asplanchna Paramecium + = Amictic ♀♀ Amictic ♀♀

Parthenogenic -Sexual Cycles Chlamydomonas Asplanchna Paramecium + + = Euglena Amictic ♀♀

Parthenogenic -Sexual Cycles Large Mictic ♀♀ Enlargement Mictic ♀♀ = Mictic ♀♀ with “Humps” Sex Mictic ♂♂

Controls on Zooplankton Distribution and Abundance Temperature  Nutrients Physical Phactors  Phish  Phytoplankton Vertical Migration Parthenogenic ↔ Sexual Cycles Predation among Zooplankton

Zoop. Distribution and Abundance: Predation among zooplankton

Predation Among Zooplankton Cyclomorphosis

Cyclomorphosis: Elongation

Cyclomorphosis: Enlargement Asplanchna Mictic ♀♀ Large Mictic ♀♀

Cyclomorphosis: Production of Lateral Spines

Cyclomorphosis: Reduction in Spines Keratella

Zooplankton in Streams and Rivers Low-Flow Areas Backwaters Reservoirs

Alternate Copepod Life Cycle  Cocopods Copepuffs