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Spectral sensitivity of vertically migrating marine copepods
Jonathan H Cohen1, Richard B Forward
1Duke University Marine Laboratory, 135 Duke Marine Lab Road, Beaufort, North Carolina 28516, USA. jhc6@duke.edu
The Biological Bulletin
|December 14, 2002
Summary
Zooplankton diel vertical migration (DVM) is driven by light. Migrating copepods show specific spectral sensitivities, unlike non-migrating species, indicating light wavelength influences their behavior.
Area of Science:
- Marine Biology
- Zooplankton Ecology
- Photobiology
Background:
- Diel vertical migration (DVM) is a key ecological process in zooplankton.
- Light serves as a primary environmental cue influencing DVM.
- Spectral sensitivity of zooplankton photoreceptors is crucial for understanding DVM.
Purpose of the Study:
- To investigate the spectral sensitivity of four coastal calanoid copepod species.
- To determine if spectral sensitivity differs between DVM and non-migratory copepods.
- To correlate photobehavioral responses with DVM patterns.
Main Methods:
- A photobehavioral approach was employed.
- Four copepod species (Centropages typicus, Calanopia americana, Anomalocera ornata, Labidocera aestiva) were exposed to light stimuli.
- Spectral sensitivity was measured across wavelengths from 350 to 740 nm.
Main Results:
- Migratory copepods (C. typicus, C. americana, A. ornata) exhibited peak photobehavioral responses at twilight wavelengths (480-520 nm).
- Non-migratory L. aestiva showed broad spectral sensitivity with multiple response peaks.
- Spectral response ranges varied among species, even within migratory groups.
Conclusions:
- Diel vertical migration in copepods is linked to specific spectral sensitivities, particularly those matching twilight conditions.
- Non-migratory species possess broader spectral sensitivity, potentially optimizing photon capture in shallow waters.
- Photobehavioral spectral sensitivity provides insight into the proximate mechanisms driving zooplankton DVM.