How Nemo finds home: the neuroecology of dispersal and of population connectivity in larvae of marine fishes
Leis, JM and Siebeck, U and Dixson, DL, How Nemo finds home: the neuroecology of dispersal and of population connectivity in larvae of marine fishes, Integrative and Comparative Biology, 51, (5) pp. 826-843. ISSN 1540-7063 (2011) [Refereed Article]
Nearly all demersal teleost marine fishes have pelagic larval stages lasting from several days to several weeks,
during which time they are subject to dispersal. Fish larvae have considerable swimming abilities, and swim in an
oriented manner in the sea. Thus, they can influence their dispersal and thereby, the connectivity of their populations.
However, the sensory cues marine fish larvae use for orientation in the pelagic environment remain unclear. We review
current understanding of these cues and how sensory abilities of larvae develop and are used to achieve orientation with
particular emphasis on coral-reef fishes. The use of sound is best understood; it travels well underwater with little
attenuation, and is current-independent but location-dependent, so species that primarily utilize sound for orientation
will have location-dependent orientation. Larvae of many species and families can hear over a range of ~100-1000 Hz,
and can distinguish among sounds. They can localize sources of sounds, but the means by which they do so is unclear.
Larvae can hear during much of their pelagic larval phase, and ontogenetically, hearing sensitivity, and frequency range
improve dramatically. Species differ in sensitivity to sound and in the rate of improvement in hearing during ontogeny.
Due to large differences among-species within families, no significant differences in hearing sensitivity among families
have been identified. Thus, distances over which larvae can detect a given sound vary among species and greatly increase
ontogenetically. Olfactory cues are current-dependent and location-dependent, so species that primarily utilize olfactory
cues will have location-dependent orientation, but must be able to swim upstream to locate sources of odor. Larvae can
detect odors (e.g., predators, conspecifics), during most of their pelagic phase, and at least on small scales, can localize
sources of odors in shallow water, although whether they can do this in pelagic environments is unknown. Little is known
of the ontogeny of olfactory ability or the range over which larvae can localize sources of odors. Imprinting on an odor
has been shown in one species of reef-fish. Celestial cues are current- and location-independent, so species that primarily
utilize them will have location-independent orientation that can apply over broad scales. Use of sun compass or polarized
light for orientation by fish larvae is implied by some behaviors, but has not been proven. Use of neither magnetic fields
nor direction of waves for orientation has been shown in marine fish larvae. We highlight research priorities in this area.