Temperature cycles affect colonization potential of calanoid copepods

Area of Science:

• Marine Biology
• Ecology
• Oceanography

Background:

• Marine calanoid copepods can become invasive species.
• Copepod fitness, crucial for colonization, depends on biochemical processes influenced by ambient temperature.
• Yearly temperature cycles and their fluctuations (amplitudes) can significantly affect marine copepod populations.

Purpose of the Study:

• To investigate how temperature cycle amplitudes impact marine copepod fitness and colonization potential.
• To develop metrics for assessing periodic (yearly) fitness in copepods.
• To model the growth and persistence of invasive copepods in variable temperature environments.

Main Methods:

• Derived approximate metrics for yearly intrinsic growth rate and weighted net reproductive rate.
• Modeled an Allee-effect free, stage-structured, fast-maturing copepod population with year-round reproduction.
• Simulated population dynamics in habitats with different yearly temperature cycle amplitudes.

Main Results:

• Yearly fitness increased substantially when copepods moved from high to low amplitude temperature fluctuation habitats, with constant mean temperatures.
• The developed fitness metrics predicted potential range expansion.
• Modeled range expansion aligned with predicted fitness gradients.

Conclusions:

• Temperature amplitude, not solely mean temperature, is a critical factor influencing marine copepod fitness and invasive potential.
• Gradients in temperature amplitude between habitats may drive the colonization success of invasive copepods.
• Further research is needed to understand the impact of temperature amplitude gradients on invasive calanoid copepods.