A New Estimate of Zooplankton Retention by Gill Rakers and Its Ecological Significance

Abstract

The probability that prey will be retained by gill rakers of white crappies Pomoxis annularis (9–15 cm total length) was determined by comparisons of size‐frequency distributions of prey in a laboratory pool and in stomach contents. White crappies trained to feed on large‐bodied Daphnia magna were released individually into a pool containing that species and an assemblage of small‐bodied species. Most attacks were directed at Daphnia magna, but several prey were ingested for every attack, and nonselective capture was assumed for the small‐bodied among them. Estimated retention probabilities for species of Ceriodaphnia, Bosmina, and Cyclops were less than 10% for mean prey sizes smaller than 0.35 mm and increased linearly with mean prey size to 100% for prey larger than 0.55 mm. In contrast, retention probabilities calculated by traditional means from distances between gill rakers predicted that all prey larger than 0.23 mm would be retained. The new retention estimates, based on actual results of the retention process, predict that many small‐bodied zooplankton present in lakes are immune from predation by white crappies because they cannot be retained by the gill rakers. Received April 1, 1982 Accepted May 25, 1983

Prey capture by the four larval instars of Chaoborus crystallinus

“…Observations on fourth-instar C. crystallinus feeding on small prey consistently resulted in more prey in the crops than the number of strikes made with the head capsule. These "extra" prey could have been captured incidentally while the larvae struck at other prey items, a phenomenon well described for planktivorous fish (Wright et al 1983). Giguere and Dill (1983) suggested that the mandibular fans might be used for filter feeding.…”

Consumption of marine snow by two species of juvenile mullet and its contribution to their growth

“…bacteria attached to particles). There is a minimum-sized particle that can be retained on the gill rakers of a species (Wright et al 1983). Therefore, there are size classes of plankton that should be too small for certain fish species to consume.…”

“…Previous s t u h e s on filter-feeding fishes have shown that as food particle size increases feeding efficiency also increases (Wright et al 1983, Friedland et al 1984. McIntyre (1983) found that gizzard shad Dorosoma cepedianum collected 24 times more food from tanks in which algal flocculation was induced by adding clay particles to the water, as compared to tanks without flocculation.…”

A review of planktivorous fishes: Their evolution, feeding behaviours, selectivities, and impacts

“…Helostoma temmincki (Liem, 1967); l Centrarchidae: bluegill sunfish, Lepomis macrochirus (Werner, 1972(Werner, , 1974(Werner, , 1977Werner & Hall, 1974Vinyard & O'Brien, 1975O'Brien et al, 1976;Werner et al, , 1981Werner et al, , 1983aWerner et al, , 1983bVinyard, 1980;Gardner, 1981;Mittelbach, 1981;Janssen, 1982); northern longear sunfish, Lepomis megalotis peltastes, and pumpkinseed, L. gibbosus (Laughlin & Werner, 1980); white crappie, Pomoxis annularis (Wright et al, 1983;Wright & O'Brien, 1984); largemouth bass fry, Micropterus salmoides (Elliot, 1976); l Percidae: Eurasian perch, Perca fluviatilis (Guma'a, 1978;Furnass, 1979;Stenson, 1980); yellow perch, Z? flavescens (Galbraith, 1967;Wong & Ward, 1972;Rasmussen, 1973); l Cichlidae: Congo tilapia, Tilapia rendalli (Caulton, 1976); blue tilapia, 7: aurea (Spataru & Zorn, 1978;Gophen et al, 1983aGophen et al, , 1983bDrenner et al, 1984b); 7Y esculenta (Greenwood, 1953); T nilotica (Moriarty, 1973;Moriarty & Moriarty, 1973); Sarotherodon galilaeus (Lauzanne & Iltis, 1975;Spataru, 1976;Spataru & Zorn, 1976;Lauzanne, 1977;Gophen, 1980;…”

“…Nevertheless, several prey may be inhaled incidentally during the capture of the pursued prey (Wright et al, 1983).…”