Anodonta Imbecillis Research Articles

Comparative response ofCeriodaphnia dubiaand juvenileAnodonta imbecillisto pulp and paper mill effluents discharged to the tennessee river and its tributaries

The responses of Ceriodaphnia dubia (daphnid) in a 7–d chronic daily-renewal bioassay and 6–d-old juvenile Anodonta imbecillis (paper pondshell mussel) in a 9–d acute daily-renewal bioassay are compared. Values for relative sensitivity to selected complex, industrial, whole-effluent samples were generated following determination of either observed or calculated no-observable-effect concentrations (NOEC). Results from tests using effluents from six pulp and paper products facilities in the Tennessee River Valley indicate that A. imbecillis juveniles are substantially more sensitive than C. dubia to selected effluents. It is suggested that a juvenile mussel bioassay should be used to assess the toxicity of effluent releases to waters with freshwater mussel resources.

Growth Rates of the Freshwater Mussel, Anodonta imbecillis Say 1829, in Five West Virginia Wildlife Station Ponds

Growth rates of a thin-shelled, freshwater bivalve mollusc, Anodonta imbe- cillis Say 1829, were studied for 3 yr (May 1984 through June 1987). A total of 487 A. imbecillis individuals were collected from five ponds at the McClintic Wildlife Station (Mason County, West Virginia). Mussels were measured for initial shell length, numbered and replaced in their respective ponds. Summer growth was determined from the recovery of 139 individuals, and annual growth was calculated for 81 recovered mussels. Increase in shell length was inversely correlated with initial shell length (r-values of -0.827 and -0.851 for summer and annual increases, respectively). A 10-yr length-age growth curve, based on annual data, was calculated for this mussel species. Growth is rapid over the 1st 4 yr; after the 4th yr, increases in shell length are slight. One of the study ponds (Pond 12) was contaminated with waterborne nitroaromatic residues. Growth of mussels from this pond was noticeably lower than that of mussels in noncontaminated ponds.

Population Dynamics of Unionicola formosa (Acari: Unionicolidae), a Water Mite with a Harem

The population dynamics of the water mite Unionicolaformosa, a symbiont of the freshwater mussel Anodonta imbecillis, were monitored for 2 years in a North Carolina farm pond. Since the density (number/mussel) of females was correlated with host-size, but males were uniformly isolated at 1/host, the sex ratio approached 80:1 (female:male) among large mussels. This harem distribution persisted throughout the year. Female mites were most abundant in winter and experienced -50 % mortality by early summer. Nymphs were present throughout the year. Size-frequency data for fernales, coupled with the pattern of occurrence of nymphs, suggested that recruitment into the adult population began in May as overwintering nymphs transformed to adults, and continued into late summer and autumn. Egg production occurred throughout the year, but oviposition and the development of eggs were seasonal, with larvae emerging from the host from late spring to early autumn. Adult U formosa probably live at least 2 years. INTRODUCTION The life cycle of freshwater mites is complex and includes the egg, prelarva, larva, protonymph (postlarval resting stage I), deutonymph (nymph), tritonymph (postlarval resting stage II) and the adult (Bottger, 1977; Hevers, 1980). Five genera of the water mite family Unionicolidae commonly occur in association with freshwater sponges, gastropods and/or mussels (Mitchell and Pitchford, 1953). The cosmopolitan genus Unionicola includes species whose life histories involve a mollusc or poriferan, either temporarily as a site for oviposition and for the postlarval resting stages (Hevers, 1980), or more permanently in associations which include parasitism of the molluscan host by nymphs and adults (Baker, 1977). The larvae of free-living, predatory species, as well as those of symbiotic species, probably all have a brief (3to 8-day) parasitic dependence upon chironomid dipterans (Davids, 1977; Booth and Learner, 1978; Jones, 1978; Hevers, 1978a, 1980). Unionicola formosa (Dana and Whelpley) occurs throughout much of North America in symbiotic associations with several genera of anodontine mussels (Bivalvia: Unionidae) (Vidrine, 1980). Field observations (Dobson, 1966; Roberts, 1977; Vidrine, 1980) and experimental behavioral studies (LaRochelle and Dimock, 1981; del Portillo and Dimock, 1982) indicate that in the southeastern U.S. the mussel Anodonta imbecillis Say is the preferred host of this mite. Although the spectrum of interactions between U formosa and its molluscan hosts is not fully known, females oviposit in the host's gills, and presumably the larvae and nymphs embed in host tissue prior to their ontogenetic transformations. The nature of any nutritional dependence of this mite upon its hosts has not been fully resolved (LaRochelle, 1979); however, the mantle cavity of the host clearly constitutes a microcosm for the mite and is the focal point for much of the biology of this species. The ecology of the Unionicolidae is less well-known than that of some other taxa of marine and freshwater mites (e.g, Davids, 1973a, 1977; Kitron, 1980; Lanciani, 1982; Riessen, 1982; Viets, 1982). Seasonal distributional data for species associated with molluscan hosts are available only for Najadicola ingens (Koenike) from New Hampshire 'Contribution No. 214 from the Tallahassee, Sopchoppy and Gulf Coast Marine Biological Association.

The effect of season and location on phosphoadenylate concentrations and adenylate energy charge in two species of freshwater clams.

Concentrations of phosphoadenylate nucleotides and the adenylate energy charge ((ATP+1/2ADP)/(ATP+ADP+AMP)) have been suggested as sensitive integrating measures of the energy state of organisms. This synoptic study investigated the seasonal and spatial variation of phosphoadenylate concentrations and AEC in two freshwater bivalve molluscs, the paper-shell clam, Anodonta imbecillis and the asian clam, Corbicula fluminea. Concentrations of all three adenylates, as well as the total adenylate concentration and adenylate energy charge of both species varied seasonally. These fluctuations were closely related to reproductive periods in both species. Total adenylate concentrations and ATP concentrations were slightly negatively correlated with shell length in A. imbecillis but the ADP and AMP concentrations and AEC were not significantly correlated with shell length. In C. fluminea the AEC was negatively correlated were positively correlated with shell length. Neither species exhibited significant differences in AEC between two collection locations. When C. fluminea collected from the Savannah River were acclimated and fed in the laboratory their AEC increased significantly.

STUDIES ON THE LIFE CYCLES OF TWO SPECIES OF FRESH-WATER MUSSELS BELONGING TO THE GENUSANODONTA

1. Aodonta grandis and Anodonta imbecillis have been studied with reference to the glochidia and later stages in the life cycles.2. Through experimental infestation, glochidia of Anodonta imbecillis have been reared under laboratory conditions through the period of transformation to the juvenile stage.3. An examination of mature individuals collected at various times of the year yielded only glochidia, showing no evidences of transformation to the juvenile stage.4. The claim that metamorphosis in Anodonta imbecillis occurs in the marsupia of the parent has not been confirmed by this investigation.5. Apomotis cyanellus served as host to the glochidia of Anodonta imbecillis.6. The transformation of glochidia of Anodonta grandis has been followed in experimental infestations using Apomotis cyanellus and Amploplites rupestris as hosts.7. Anodonta grandis may be differentiated from Anodonta grandis gigantea on the basis of glochidial measurements.

THE EXISTENCE OF A SHORT REPRODUCTIVE CYCLE INANODONTA IMBECILLIS

Anodonta imbecillis cannot be classed with either long or short term breeders as defined by Lefevre and Curtis. In specimens obtained at Fairport, Iowa, a complete reproductive cycle (including metamorphosis from glochidia to juvenile mussels, for reproduction in this species does not depend on parasitism) is completed in from 3 to 4 weeks during the late summer. Another cycle begins after an interval varying from 2 to 3 days to 2 weeks. Gravid A. imbecillis have been found in all months but April. It is possible therefore that this short reproductive cycle is repeated throughout the year.