Vertical distribution and diel migration in the iridescent copepods of the family Sapphirinidae:a unique example of reverse migration?

Abstract

The vertical distributions and diel vertical migrations of the sapphirinid copepods of the genera Sapphirina and Copilia were investigated in the tropical and subtropical waters in the eastern Indian Ocean, the South China Sea and the western Pacific. Vertically stratified plankton samples were collected at a total of 11 stations including 5 day-night stations and 1 station occupied for a 20 h serial sampling, in the years 1977, 1981, 1988 and 1991. The sapphirinids, the family as a whole, were collected essentially in the upper 200 m, and are considered as typical epipelagic copepods. Three groups of species were recognized according to their patterns of vertical distributions: the upper epipelagic species, the lower epipelagic species, both of the genus Sapphirina, and 2 species of Copilia which showed relatively deep and broad vertical distributions. Marked reverse diel vertical migrations were observed in the upper epipelagic species, S. gastrica, S. stellata, S. nigromaculata and S. auronitens, and, to a lesser extent, in the lower epipelagic species, S. metallina. In the species exhibiting reverse migrations, the vertlcal distnbutions in the daytime were mostly unimodal, while bimodal distributions were occasionally observed at night. A comparison of these vertical patterns with the specific iridescent color patterns in the male and the distribution of light in the ocean suggested that the daytime distributions of the sapphinnids are determined by the underwater Light condition as a proximate cue. It was also hypothesized that the well-developed eye, the iridescence of the male and the daytime shoaling in the sapphirinids are closely related and constitute a presumed mate-findlng mechanism which may be unique in the oceanic plankton.

Iridescence: a functional perspective

“…As further support for the influence of sensory drive on the evolution of iridescence, female guppies in lowpredation environments preferred males with blue or silver iridescence, as did females in habitats with higher transmission of short wavelengths relative to long wavelengths (Endler & Houde 1995). Finally, among iridescent sapphrinid copepods, different species are found at different depths in the water column, and variation in the dominant hue of each species corresponds to the wavelengths available at that depth, supporting an influence of sensory drive (Chae & Nishida 1995). S122 Review.…”

Composição e distribuição da família paracalanidae (Copepoda: Calanoida) ao Largo de São Sebastião, estado de São Paulo-Brasil, com ênfase em três espécies de paracalanus

“…A biomassa zooplanctônica, na zona eufótica, tende a ser maior à noite que durante o dia (Napp et ai., 1988;Hays, 1995). Migradores verticais como os copépodos Calanoida, deslocam-se para a superficie ao anoitecer e descem para as camadas mais profundas ao amanhecer (Pagano et ai., 1993), evitando sua exposição aos predadores visuais (Zaret & Kerfoot, 1975;Chae & Nishida, 1995;Hays et aI., 1995). A migração pode ser provocada também pela intolerância aos raios ultravioletas (Johnson, 1946apud Vinogradov, 1970, os baixos teores de oxigênio da água (Sameoto, 1986), a temperatura e a concentração de matéria orgânica particulada (Paffenhõfer, 1983).…”

Diurnal and tidal vertical migration of pre-settlement King George whiting Sillaginodes punctata in relation to feeding and vertical distribution of prey in a temperate bay

“…The most commonly recognised form of vertical migration is 'diurnal vertical' or 'nocturnal' migration where plankters distribute at the surface at night and migrate deeper during the day (Hutchinson 1967, Haney 1988; however, 'reverse' diurnal migration where animals move downward at night and upwards during the day is also common (Haney 1988, Chae & Nishida 1995. A range of vertical migratory behaviours has been recorded between these extremes (Haney 1988) and a full range of migratory behaviour can be expressed in the same population (Ohman 1990).…”