General Ecology of Six Species of Hawaiian Cardinalfishes

Date
1978-07
Authors
Chave, E.H.
Journal Title
Journal ISSN
Volume Title
Publisher
University of Hawaii Press
Abstract
Six species of cardinalfishes (Pisces: Apogonidae) are found together in shallow marine waters of Hawaii day and night. All six species remain in holes and caves during the day and emerge at night when they feed. The centers of abundance, ecological ranges, and other requirements of the six species differ during their life histories. During the day, Foa brachygramma is found in crevices or rubble on shallow, calm reef flats and unlike the other species may enter areas of low salinity and poor circulation. Young Foa are found under ledges in deeper water than are adults. Apogon menesemus is most abundant in clear, relatively deep water, especially where the substrate is almost completely covered by live coral. It lives at the back of holes or caves. Apogon erythrinus frequently inhabits small, dark holes in either dead coral heads or basalt cliff caves. Apogonichthys waikiki is most often found in pairs in large, widely spaced living coral heads. Apogon maculiferus adults are found under ledges and in caves at depths of over 20 meters. Young A. maculiferus aggregations are found in shallow water under ledges or at cave entrances. Apogon snyderi has the widest habitat distribution, although it is restricted to substrates with some sand. It lives in the middle of caves close to the floor, and under rubble, coral heads, or ledges. Each species reacts differently to increasing or decreasing light levels. Generally, a species' response to a given amount of light in the laboratory is similar in the field. In shallow water, adult Apogonichthys waikiki is not seen outside holes unless light intensity is less than 1.75 fc. Apogon erythrinus emerges or enters holes at about ±5 fc, A. menesemus at about 16 fc, and A. snyderi at about 88 fc. Adult Foa brachygramma leaves or enters cover at about 2400 fc, young Foa at about 700 fc. Adult Apogon maculiferus emerge and enter cover at about 100 fc and young A. maculiferus at about 2700 fc. Diurnal predators remove more individuals of species living in brighter light intensities; cavedwelling predators remove those living in lower light intensities. At night all species are opportunistic carnivores on zooplankton and benthic invertebrates, but there are differences in their foraging locations. Apogon snyderi and A. maculiferus forage mostly over light-colored substrates, but A. maculiferus feeds nearer dawn, higher in the water, in aggregations, and closer to large objects than does A. snyderi. Apogon erythrinus is found no more than 3 cm from hard substrates, vertical and horizontal. The other three species are found near large underwater objects. Foa brachygramma remains near the bottom when there is a current, and groups of fish rise in the water column on quiet nights when there is a half to full moon. Apogon menesemus is most often found in midwater and is often located in the shadow of large underwater objects on moonlit nights. Apogonichthys waikiki hovers near holes in the isolated coral heads where it is found diurnally. Nocturnal predators take individuals of all species except A. waikiki.
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Citation
Chave EH. 1978. General ecology of six species of Hawaiian cardinalfishes. Pac Sci 32(3): 245-270.
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