5.3 Seasonal succession
6 min read•august 20, 2024
Seasonal succession in is a dynamic process driven by physical, chemical, and biological factors. These changes impact water temperature, nutrient availability, and organism populations throughout the year, shaping ecosystem structure and function.
Understanding seasonal patterns is crucial for managing water resources and predicting ecosystem responses to environmental change. From spring turnover to winter stagnation, each season brings unique challenges and opportunities for lake organisms and ecosystems.
Seasonal patterns in lakes
- Seasonal patterns in lakes are driven by changes in physical, chemical, and biological factors that influence the structure and function of aquatic ecosystems
- Understanding seasonal succession is crucial for managing water resources, assessing ecosystem health, and predicting responses to environmental change
- Seasonal patterns vary among lakes depending on their morphology, geographic location, and watershed characteristics
Factors influencing seasonal succession
Physical factors
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- Solar radiation and photoperiod drive seasonal changes in water temperature and light availability
- Wind stress influences mixing and stratification patterns
- Inflows and outflows affect water residence time and nutrient loading
- Lake morphology (depth, surface area) modulates the impact of physical factors
Chemical factors
- Nutrient availability (nitrogen, phosphorus) limits primary production and shapes phytoplankton community composition
- Dissolved oxygen concentrations are influenced by water temperature, mixing, and biological processes
- pH and alkalinity affect the solubility and speciation of nutrients and metals
- Dissolved organic matter influences light attenuation and nutrient cycling
Biological factors
- Phytoplankton growth and succession are driven by nutrient availability, light, and grazing pressure
- Zooplankton population dynamics are influenced by food availability (phytoplankton) and by fish
- Benthic organisms (macrophytes, invertebrates) interact with pelagic communities through nutrient cycling and habitat provision
- Fish populations respond to changes in prey availability and habitat conditions
Spring succession
Spring turnover and mixing
- Increasing solar radiation and air temperature lead to the breakdown of thermal stratification
- Vertical mixing of the water column redistributes nutrients and oxygen
- Isothermal conditions facilitate deep convective mixing
Nutrient availability in spring
- Mixing replenishes surface waters with nutrients accumulated in the hypolimnion during winter
- High nutrient concentrations support rapid phytoplankton growth
- Nitrogen and phosphorus are often co-limiting factors for primary production
Phytoplankton blooms
- Diatoms and cryptophytes dominate early spring phytoplankton communities
- Rapid growth leads to high biomass and chlorophyll concentrations
- Blooms may be triggered by increased light availability and nutrient supply
Zooplankton population dynamics
- Overwintering zooplankton populations (copepods, rotifers) respond to increased food availability
- Cladocerans (Daphnia) emerge from resting eggs and contribute to grazing pressure on phytoplankton
- Zooplankton grazing can influence the timing and magnitude of phytoplankton blooms
Summer stratification
Thermal stratification
- Increasing solar radiation and air temperature lead to the formation of distinct thermal layers
- Epilimnion (warm, well-mixed surface layer) is separated from the hypolimnion (cold, dense bottom layer) by the metalimnion
- Stratification stability depends on the temperature gradient and wind stress
Epilimnion characteristics
- Warm, well-oxygenated, and nutrient-depleted due to phytoplankton uptake
- High light availability supports photosynthesis and primary production
- Diurnal temperature fluctuations and wind mixing
Metalimnion and thermocline
- Region of rapid temperature change (thermocline) acts as a barrier to vertical mixing
- Nutrient and oxygen gradients are often associated with the metalimnion
- Deep chlorophyll maximum may develop at the thermocline due to optimal light and nutrient conditions
Hypolimnion characteristics
- Cold, dense, and isolated from surface mixing
- Nutrient accumulation from settling organic matter and sediment release
- Oxygen depletion due to microbial decomposition and limited gas exchange
Nutrient depletion in epilimnion
- Phytoplankton uptake and sedimentation lead to nutrient limitation in the surface layer
- Nitrogen and phosphorus deficiency can shift phytoplankton community composition
- Nutrient regeneration in the epilimnion is limited by stratification
Phytoplankton community shifts
- Nutrient depletion and grazing pressure favor small, motile, and grazing-resistant species
- Cyanobacteria may dominate under low nitrogen and high light conditions
- Dinoflagellates and chrysophytes are common in nutrient-poor epilimnia
Zooplankton vertical migration
- Diel vertical migration allows zooplankton to balance food availability and predation risk
- Daytime descent to the metalimnion or hypolimnion reduces visibility to fish predators
- Nighttime ascent to the epilimnion provides access to phytoplankton prey
Fall turnover
Cooling and mixing of water column
- Decreasing air temperature and solar radiation lead to surface cooling and convective mixing
- Deepening of the mixed layer erodes the thermocline and destabilizes stratification
- Complete mixing (turnover) occurs when the water column becomes isothermal
Nutrient redistribution
- Mixing of the water column redistributes nutrients accumulated in the hypolimnion
- Increased nutrient availability in the surface layer can stimulate phytoplankton growth
- Nutrient inputs from the watershed (leaf litter, runoff) contribute to nutrient loading
Phytoplankton and zooplankton responses
- Increased nutrient availability and mixing can trigger a fall phytoplankton bloom
- Diatoms and cryptophytes often dominate fall phytoplankton communities
- Zooplankton populations decline as water temperature decreases and food availability becomes limited
Winter stagnation
Ice cover and light limitation
- Ice formation on the lake surface reduces light penetration and gas exchange
- Snow cover on ice further attenuates light and limits photosynthesis
- Low light availability suppresses primary production and phytoplankton growth
Oxygen depletion in hypolimnion
- Microbial decomposition of organic matter consumes oxygen in the absence of photosynthesis
- Limited gas exchange and mixing lead to hypoxic or anoxic conditions in the hypolimnion
- Oxygen depletion can stress or eliminate sensitive benthic organisms and fish
Overwintering strategies of organisms
- Phytoplankton and zooplankton may form resting stages (spores, cysts) to survive unfavorable conditions
- Benthic invertebrates may enter diapause or migrate to deeper, oxygenated sediments
- Fish may reduce activity, aggregate in oxygenated areas, or migrate to inflows or outflows
Interannual variability
Climate effects on seasonal succession
- Year-to-year variations in temperature, precipitation, and wind patterns influence the timing and magnitude of seasonal events
- Warmer winters and earlier ice-out can lead to earlier spring blooms and longer growing seasons
- Changes in the frequency and intensity of storms can alter nutrient loading and mixing patterns
Anthropogenic impacts on succession
- Nutrient enrichment from land use and wastewater discharge can intensify phytoplankton blooms and alter community composition
- Climate change is expected to increase water temperatures, alter stratification patterns, and shift species ranges
- Invasive species introductions can disrupt native communities and alter seasonal succession patterns
Implications of seasonal succession
Nutrient cycling and budgets
- Seasonal patterns of nutrient uptake, regeneration, and sedimentation influence lake nutrient budgets
- Internal loading from sediments can sustain phytoplankton blooms during stratified periods
- Quantifying nutrient fluxes is essential for understanding ecosystem metabolism and predicting responses to perturbations
Food web dynamics
- Seasonal changes in primary production and phytoplankton composition propagate through the food web
- Phytoplankton-zooplankton interactions (grazing, nutrient recycling) shape energy transfer and trophic structure
- Fish recruitment and growth are influenced by the timing and magnitude of plankton production
Water quality and clarity
- Phytoplankton blooms and organic matter production affect water transparency and color
- Seasonal changes in nutrient concentrations and algal biomass influence drinking water treatment and recreational use
- Harmful algal blooms (cyanobacteria) can impair water quality and pose health risks to humans and wildlife
Fisheries and ecosystem management
- Understanding seasonal patterns is crucial for managing fish populations and setting harvest quotas
- Timing of fish stocking and habitat management actions can be optimized based on seasonal succession
- Monitoring seasonal indicators (water temperature, nutrient concentrations, plankton communities) informs adaptive management strategies
Key Terms to Review (18)
Biodiversity: Biodiversity refers to the variety of life forms in a given ecosystem, encompassing the diversity of species, genetic variations, and ecological processes. This concept is crucial for maintaining ecosystem stability and resilience, influencing interactions among organisms and their environment. It plays a significant role in seasonal changes, species composition, and the complex relationships within aquatic habitats.
Climax community: A climax community is a stable and mature ecological community that has reached a steady state of development, where the species composition remains relatively constant over time. This community represents the final stage of ecological succession, where environmental conditions favor certain species that dominate the landscape, creating a balance among organisms, and sustaining biodiversity.
Colonization: Colonization refers to the process by which a species establishes itself in a new habitat, often leading to changes in the ecological dynamics of that environment. It involves the initial arrival and subsequent establishment of organisms, and is influenced by factors such as resource availability, competition, and environmental conditions. The impact of colonization can be seen through seasonal patterns, life cycles of organisms, and the introduction of non-native species.
Competition: Competition refers to the interaction between organisms or species that vie for the same resources, such as food, space, or mates, in a given environment. This struggle can shape community structure and influence population dynamics, affecting everything from seasonal changes in biodiversity to the functioning of food webs.
Facilitation Model: The facilitation model is a concept in ecology that describes how certain species can promote the growth and establishment of other species within a community, particularly during the process of succession. In this model, early colonizers modify the environment in ways that make it more hospitable for subsequent species, leading to a more diverse and stable ecosystem over time.
Field experiments: Field experiments are research studies conducted in real-world settings to investigate ecological processes, interactions, and responses in natural environments. These experiments allow scientists to observe phenomena in their natural context, providing insights into how variables affect ecosystems and species over time, especially during specific periods like seasonal succession.
Frederic Clements: Frederic Clements was an American plant ecologist known for his pioneering work in community ecology, particularly in the concept of plant succession. He proposed that ecological communities progress through a series of stages, ultimately reaching a stable endpoint called a climax community. His ideas on succession and plant communities laid the groundwork for understanding how ecosystems change over time, especially in the context of seasonal variations.
H.A. Gleason: H.A. Gleason was a prominent ecologist known for his work on plant succession and community ecology, particularly his ideas on the role of individual species in ecological communities. His research emphasized that ecological communities are not static but are dynamic systems shaped by various environmental factors, including disturbance and seasonal changes.
Inhibition Model: The inhibition model is a theoretical framework that explains how the presence of certain species in an ecosystem can limit or inhibit the growth and survival of other species. This model is particularly relevant in understanding community dynamics, as it emphasizes the interactions among species during processes like seasonal succession, where competition and resource availability play crucial roles.
Lakes: Lakes are large bodies of freshwater or saline water surrounded by land, serving as vital ecosystems that support diverse forms of life. They play a crucial role in regulating water flow, providing habitat for various organisms, and influencing local climates. Additionally, lakes are important in understanding nutrient cycling, biological diversity, and the impacts of human activity on freshwater resources.
Longitudinal Studies: Longitudinal studies are research methods that involve repeated observations or measurements of the same subjects over an extended period. This approach allows scientists to track changes, developments, or trends within a specific population, providing valuable insights into processes like seasonal succession. By examining how ecosystems evolve through time, researchers can better understand the dynamics of environmental factors and their impacts on aquatic communities.
Pioneer stage: The pioneer stage refers to the initial phase of ecological succession, where the first organisms to colonize a barren or disturbed environment establish themselves. These organisms, typically hardy species like lichens and mosses, play a crucial role in modifying the environment and paving the way for subsequent species to thrive, which is essential for the process of seasonal succession.
Predation: Predation is the biological interaction where one organism, the predator, hunts and consumes another organism, the prey. This interaction plays a crucial role in regulating population dynamics, influencing community structure, and driving evolutionary adaptations within ecosystems.
Primary succession: Primary succession is the ecological process that occurs in lifeless environments where no soil exists, leading to the establishment of a biological community over time. This process typically begins after a significant disturbance, like volcanic eruptions or glacial retreats, which exposes bare rock or sand and initiates a gradual series of changes in species composition. It highlights how ecosystems can develop from scratch, starting with pioneer species and progressing to more complex communities through stages.
Secondary succession: Secondary succession is the ecological process that occurs after a disturbance in an area that previously supported life, leading to a gradual reestablishment of a biological community. This type of succession happens in environments where soil and seeds remain intact, allowing for quicker recovery than primary succession, which starts from bare rock or lifeless substrates. Over time, a series of species will replace one another, leading to a mature ecosystem.
Trophic Levels: Trophic levels are the hierarchical stages in a food chain that represent the flow of energy and nutrients from one organism to another. They categorize organisms based on their feeding relationships and energy acquisition, ranging from primary producers at the base, through various levels of consumers, to decomposers at the top. Understanding trophic levels helps illuminate the structure and dynamics of ecosystems.
Vegetation change: Vegetation change refers to the alterations in plant communities and ecosystems over time due to various environmental factors, including seasonal shifts, climate variations, and human activities. These changes can be cyclical or gradual and are often observed through processes such as succession and disturbance recovery. Understanding vegetation change is crucial for studying ecosystem dynamics and biodiversity.
Wetlands: Wetlands are unique ecosystems characterized by the presence of water, either permanently or seasonally, which supports a rich diversity of plant and animal life. These areas act as critical interfaces between land and water, providing numerous ecological functions such as habitat for wildlife, water filtration, flood control, and carbon storage. The dynamic nature of wetlands influences seasonal changes in biodiversity, the role of organisms within food webs, and the interactions between various species.