Gravel Bottom Research Articles

The Gonads, Larvae, and Budding of the Polystyelid Ascidians Stolonica and Distomus

Stolonica socialis (Hartmeyer) and Distomus variolosus Gaertner are two species of styelid ascidians with a capacity for budding and colony formation, found on both sides of the western end of the English Channel. Distomusoccurs immediately below the level of extreme low spring tides, commonly encrusting the sides of rocks and laminarian bases. Stolonica is more usually found by dredging in deeper water, on the upper sides of stones or gravel bottom. Their external appearance and general internal anatomy have been well described and beautifully illustrated in the monograph of Lacaze-Duthiers and Delage (1892), while the process of budding has been investigated by Selys-Longchamps (1917).

Propagation of the Creek Chub in Ponds with Artificial Raceways

Successful spawning of the creek chub (Semotilus a. atromaculatus) was achieved in a specially designed raceway. An artificial stream, having a gravel bottom with pools and riffles, was constructed within the basin of a pond in which brood stock were introduced. Spawning activity commenced in late April and terminated in early May. A heavy mortality occurred among the brood stock when the ratio of males was equal to, or greater than that of the females. A better survival was attained by increasing the number of females. The breeding fish had a tendency to concentrate in certain zones of the spawning raceway, and as a result many redds were destroyed in the overworked areas. To offset this condition, thus increasing the efficiency of the raceway, deposited eggs were removed from the beds and successfully cultured in a hatchery by the use of Mechean jars and egg trays. The complete incubation period (fertilized egg to free-swimming fry) was about 25 days at a mean temperature of 55° F. Several rearing ponds were stocked with 8-day-old fry; others with 20-day-old fry. Though the 8-day-old fry were found to tolerate long-distance transporting, they did not survive in any appreciable numbers after introduction into rearing ponds. The stocking of ponds with 20-day-old fry was more successful, for more than 50 percent of the fry survived. Production in ponds where the fish had to rely on a natural food supply was light as compared to that achieved in a pond where artificial feeding was practiced.

Bottom Fauna of Portions of the Cowichan River, B.C.

The yields per sq. m. computed as (1) av. wet wt. and (2) no. of organisms were: pool—36.91 g., 745; riffles—14.60 g., 1061; creek—8.25 g., 536. Vegetation is the most productive type of habitat, followed by mud, rubble, gravel bottom. The river may be designated as a "Trichoptera stream". No close correlation was found between no. of organisms in bottom fauna and no. in trout stomachs, thus suggesting discrimination among trout for food organisms.

Hot Springs, S. D., as a Health Resort.

Chicago, Ill., June 1, 1899. To the Editor: —Hot Springs is situated in the Black Hills, about 3400 feet above the sea-level, in a valley surrounded by mountains not over 5000 feet in altitude, and it differs from the surrounding country meteorologically and geologically. Deadwood, which is about ninety miles distant, is much colder, and about 5000 feet above sea-level, which may account for the difference. Spearfish, fourteen miles from Deadwood is about 3500 feet about sea-level and is much colder than Hot Springs during the winter. This applies with equal truth to all localities thirty or more miles distant from Hot Springs. It derives its name from the large number of mineral springs which supply all the bath-houses with water not exceeding 90 degrees F. One very pleasant feature is an enormous plunge-bath, supplied by innumerable springs percolating through a gravel bottom, thereby ensuring constant cleanliness and drainage. The