Ictiobus

Abstract: The external morphology of Lernaea cyprinacea L. in Vigo Co., Indiana, was more variable than has been previously reported. The pregenital prominence was absent in small lernaeids, then de- veloped as a single protuberance, which doubled as the female copepod lengthened and matured. No correlation was found between the location on the host fish and the direction of torsion. Sixteen species of fishes, taken in Vigo Co., were parasitized by L. cyprinacea. They were: Notropis blennius,* N. atherinoides,* N. spilopterus,* N. volucellus,* Semotilus atromaculatus,* Phenacobius mirabilis,* Hybognathus nu- chalis,* Ictiobus niger,* I. cyprinellus,* Lepomis macrochirus, Microp- terus salmoides, Pomoxis annularis,* Catostomus commersoni, Esox americanus,* Moxostoma erythrurum,* and Percina maculata* (asterisk denotes new host records). L. cyprinacea parasitized 0.8% of the fishes examined. Usually there was one parasite per fish, attached near a fin.

Abstract: Experimental mesocosm studies revealed that the presence of benthivorous smallmouth buffalo (Ictiobus bubalus) significantly enhanced turbidity, phytoplankton biomass, ammonium (NH4 +), and total nitrogen (N) and phosphorus (P) concentrations in a shallow, aerobic, hypereutrophic oxbow lake. The effects of Ictiobuson water quality are similar to the results of experiments performed on other benthivorous fish species. Prior studies have suggested that enhanced phytoplankton biomass in the presence of benthivorous fishes is a result of P excretion by fish and physical relocation of sediment P to the water column. However, our results revealed that enhanced microbial NH4 + regeneration and subsequent uptake by phytoplankton may also be an important factor causing increased phytoplankton biomass levels in the presence of benthivorous fishes. Net sediment plus water column particle NH4 + fluxes were over six times higher in the presence of Ictiobus, relative to the control. Increased biological demand...

Abstract: Intestinal tracts of 541 buffalofishes, genus Ictiobus (428 bigmouth, 57 black, and 56 small-mouth) caught in 1966–69 in central Arizona reservoirs were analyzed. Bigmouth buffalo (I. cyprinellus) from Roosevelt and Apache lakes fed mostly on planktonic algae and crustaceans, with indications of a near-bottom feeding habit. Black (I. niger) and smallmouth (I. bubalus) buffalo fed on benthic macro-invertebrates, with molluscs being the most important group utilized by both species.

Abstract: The life cycle of the caryophyllaeid cestode Archigetes iowensis was studied in naturally and experimentally infected hosts. Adults are seasonal parasites of the fish, Cyprinus carpio, while larvae occur in the seminal vesicles of the oligochaete, Limnodrilus hoffmeisteri. Procercoids are characterized by a well-formed scolex, fully developed reproductive organs, and by a cercomer. Larvae occasionally produce eggs within the annelid host. Feedings of infected annelids to fish did not provide conclusive evidence regarding the manner in which fish acquire their infections. The periodicity of adults in fish seems to result from changes in the resistance of carp to these helminths. Life cycles for members of the caryophyllaeid genera Archigetes Leuckart and Biacetabulum Hunter were studied in an attempt to resolve taxonomic problems. Archigetes iowensis Calentine, the subject of this report, normally produces eggs within a fish host, but procercoids occasionally exhibit progenetic development within the annelid intermediate host. Pertinent literature was cited earlier (Calentine, 1962); more recent accounts of Archigetes include Brinkhurst et al. (1962), Kulakowskaja (1962a, b), and Nybelin (1963). Studies on Biacetabulum and taxonomic considerations will be reported later. MATERIALS AND METHODS Natural history studies were conducted on the Iowa River (Franklin and Hardin counties, Iowa, USA). A total of 975 fishes representing 20 species was examined for the presence of intestinal parasites. Members of the cyprinid genera Cyprinus, Hybopsis, Notropis, Pimephales, and Semotilus and those of the catostomid genera Carpiodes, Catostomus, Hypentelium, Ictiobus, and Moxostoma were included. Carp (Cyprinus carpio L.), the Received for publication 10 October 1963. * Part of a doctoral thesis, Iowa State University. This study was supported in part by National Science Foundation Grants (G-9022 and B-6844) under the direction of M. J. Ulmer, and in part by a Public Health Service predoctoral fellowship (GPM-18,590) from the National Institutes of Health. t Present address: Department of Biology, Wisconsin State College, River Falls, Wisconsin. only fish host found for A. iowensis, were examined 9 months of the year (March through November) during the interval 1961 to 1963. Cestodes were fixed (without pressure) in AFA and oligochaetes were preserved in Bouin's fluid. Specimens were processed in the usual manner using carmine stains for whole mounts and hematoxylin for most sections. Egg development was followed in stream water at room temperature. Feeding experiments were conducted by mixing embryonated eggs with a small quantity of mud, to which 72 to 99 tubificids were added. After 1 to 3 days exposure, annelids were removed and maintained in a separate container. All oligochaetes were held in mud under aeration at room temperature and were fed a mixture of oatmeal, cornmeal, and commercial fish food. Tubificids used in experiments were either laboratory-reared specimens or worms collected in nature and maintained in the laboratory 3 to 6 months prior to use. Fish used in experiments were taken from waters where Archigetes was apparently absent. Small fish were allowed to ingest infected annelids while the larger fish were force fed.