ABSTBRCTPlankton collections near coral reefs were made by hand-towing nets while swimming and by using a suction device for sampling caves. Plankton in sheltered areas was considcrably different from that in nonsheltered areas; some plankton forms maintained position near coral reefs, indicating that the terms planktonic and epibenthic may represent extremes of a behavior continuum.Copepods were observed to swarm and mysids to school on the reef. Mysids ancl nesting pomacentricls exhibit a loosely developed commcnsalism, Offshore plankton probably represents a net energy gain to the reef.

Observations by SCUBA in Georgian Bay and Algonquin Park, Ont., indicate fish have specific habits of diurnal, crepuscular, and nocturnal activity in freshwater lakes. Of 21 species investigated, 17 either schooled or aggregated in the daytime, but only one (Osmerus mordax) schooled at night. The number of fish apparent at night in shallow water was greater than in the daytime primarily because of the influx of offshore species and lack of cover for resting diurnal species. Color changes parallel those reported in tropical oceans; at night a barred or mottled pattern was assumed by some fish resting on the bottom and bold daytime horizontal patterns faded. The parallel evolution of these color patterns in fresh and salt water suggests a strong evolutionary pressure for prey animals to disguise body shape when at rest at night, and that bold color patterns are disadvantageous when swimming at night.

Observations of the reproductive behavior of splake (Salvelinus fontinalis × S. namaycush) planted in Jack Lake, Algonquin Park, Ont., indicated that they spawned on rocky shoals from late October to early November. In mid-October, splake approached the spawning locations. By late October females had selected redd sites and dominant males were aggressively defending the sites that had been cleared by the females, against other males. Redd digging was variable in duration and frequency. Depth of water over redds varied between 0.5 and 4 m. No attempts were made to cover the eggs, most of which settled into the crevices between rocks. Males and females used acoustic signals during both aggression and courtship. The male initiated courtship by maintaining his head over the female's tail, then crisscrossing over the tail. Parallel positioning of the two sexes was a prerequisite to release of sex products. Visual and sonic cues appeared to be used in sequencing behavior. Circling functioned as a neutral action to which any other courting behavior could revert. Nest digging ceased after completion of egg deposition. A swim-in-place behavior of the female was a positive indicator of egg deposition. Egg predation by adult splake was observed, but it appeared to offer no serious threat to natural reproduction. Laboratory observations of splake reproductive behavior in aquaria did not indicate any behavioral obstacles to successful natural reproduction. Courtship behavior and egg deposition in the artificial spawning beds was followed by normal development and emergence of fry.Key words: splake, reproductive behavior, Ontario, visual and acoustic signaling

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A two-and-a-half month fish-collecting expedition to the Chagos Archipelago yielded specimens of 98 species (in 36 genera) of gobioid fishes. Ninety species belong to the Gobiidae, three to the Eleotrididae, one to the Kraemeriidae , and four to the Microdesmidae. Additional species, not collected by us, are Paragunnellichthys fehlmani (Microdesmidae), described from five specimens collected at Diego Garcia, and