Aquatic Ecasystems — Our Liviiii; Ri'\iiiines 



For further information: 



Arthur E. Bogan 



Freshwaler MiilluM;an Research 



36 Venus Way 



Sewell. NJ OSliso 



TiiloldDhi i)Hii;nifha (Figs. I and 2) is the 

 only aquatic gastropod now federally listed as 

 endangered; none is listed as threatened, 

 although 104 species of aquatic gastropods 

 from Alabama are on the federal candidate list. 

 Most are from the Coosa and the Cahaha rivers 

 (Table I). Conservation and recovery of the 

 remaining diversity will require immediate 

 action to prevent further declines and extinc- 

 tions. This will necessitate action to improve 

 water quality across the basin and to decrease 

 the amount of silt entering the streams and 

 rivers. In addition, the survey of the aquatic gas- 

 tropod fauna of the Mobile Bay basin is not 

 complete, and additional fieldwork in the main 

 channels of the larger rivers is needed, especial- 

 ly on the vertical limestone wall habitats. 



References 



Athearn, H. 1970. Discus.sion of Dr, Heard's paper. 

 Malacologia 10(1):28-.^1. 



Bogan, A.E., and J.M. Pierson. 199.?a. Survey of the aquat- 

 ic gastropods of the Coosa River Basin, .Alabama: 1992. 

 Final report submitted to Alabama Natural Heritage 

 Program. Montgomery. 14 pp. 



Bogan, A.E.. and J.M. Pierson. 199.^b. Survey of the aquat- 

 ic gastropods of the Cahaba River Basin. Alabama: 1992. 

 Pinal report submitted to Alabama Natural Heritage 

 Program. Montgomery. 20 pp. 



Burch. J.B. 1989. North American freshwater snails. 



Malacological Publications. Hamburg, MI. ,^6,^ pp, 

 Goodrich. C. 1922. The Anculosae of the Alabama Ri\er 



drainage. University of Michigan. Museuin of Zoology, 



Miscellaneous Publ. 7:1-57. 

 Goodrich, C. 1924. The genus Gyiotcmui. University of 



Michigan. Museum of Zoology, Miscellaneous Publ. 



12:1-29. 

 Goodrich, C, 19.^6. Goniobasis of the Coosa River, 



Alabama. University of Michigan. Museum of Zoology, 



Miscellaneous Publ. 31:1-60. 

 Goodrich. C. 1944a. Certain operculates of the Coosa River. 



The Nautilus 5811): 1-10. 

 Goodrich. C. 1944b. Pulmonates of the Coosa River. The 



Nautilus 58(1): 11-15. 

 Heard. W.H. 1970. Eastern freshwater niollusks (II). The 



south Atlantic and gulf drainages. Malacologia 10(1):23- 



27, 

 Hershler. R., J.M. Pierson. and R.S. Krotzer. 1990. 



Rediscovery of Tutotomu iiuii^nifua (Conrad) 



(Gastropoda: Viviparidae). Proceedings of the Biological 



Society of Washington 103(4):815-S24. 

 Palmer, S. 1986. Some extinct molluscs of the U.S.A. Atala 



13(1): 1-7. 

 Stansbery. D.H. 1971. Rare and endangered niollusks in 



eastern United Slates. Pages 5-18 in S.E. Jorgenson and 



RE. Sharp, eds. Proceedings of a Symposium on Rare 



and Endangered Mollusks (Naiads). U.S. Bureau of 



Sport Fisheries and Wildlife. Washington. DC. 

 Stein, C.B. 1976. Gastropods. Pages 21-41 in H. Boschung. 



ed. Endangered and threatened species of Alabama. Bull. 



Alabama Museum of Natural History 2. 



Protozoa 



by 



Diana Lipscomb 



George Washington 



Unirersitv 



The diverse assemblage of organisms that 

 carry out all of their life functions within 

 the confines of a single, complex eukaryotic 

 f\ei' glossary) cell is called protozoa. 

 Pcinimecium. Euglena, and Amoeba are well- 

 known examples of these major groups of 

 organisms. Some protozoa are more closely 

 related to animals, others to plants, and still oth- 

 ers are relatively unique. Although it is not 

 appropriate to group them together into a single 

 taxonomic category, the research tools used to 

 study any unicellular organism are usually the 

 same, and the field of protozoology has been 

 created to cairy out this research. The unicellu- 

 lar photosynthetic protozoa are sometimes also 

 called algae and are addressed elsewhere. This 

 report considers the status of our knowledge of 

 heterotrophic protozoa (protozoa that cannot 

 produce their own food). 



Free-living Protozoa 



Protozoans are found in all moist habitats 

 within the United States, but we know little 

 about their specific geographic distribution. 

 Because of their small size, production of resis- 

 tant cysts, and ease of distribution from one 

 place to another, many species appear to be cos- 

 mopolitan and may be collected in similar 

 microhabitats worldwide (Cairns and Ruthven 

 1972). Other species may have relatively nar- 

 row limits to their distribution. 



Marine ciliates inhabit interstices of sedi- 

 ment and beach sands, surfaces, deep sea and 

 cold Antarctic environments, planktonic habi- 

 tats, and the algal mats and detiitus of estuaries 

 and wetlands. Our actual knowledge of salinity, 

 temperature, and oxygen requirements of 

 marine protozoa is poor (although some groups, 

 such as the foraminifera. are better studied than 

 others), and even the broadest outlines of their 

 biogeographic ranges are usually a mystery. In 

 general, freshwater protozoan communities are 

 similar to marine communities except the spe- 

 cialized interstitial fauna of the sand is largely 

 missing. In freshwater habitats, the foraminifera 

 and radiolaria common in marine environments 

 are absent or low in numbers while testate 

 amoebae exist in greater numbers. Relative 

 abundance of species in the marine versus 

 freshwater habitat is unknown. 



Soil-dwelling protozoa have been docu- 

 mented from almost every type of soil and in 

 every kind of environment from the peat-rich 

 soil of bogs to the dry sands of deserts. In gen- 

 eral, protozoa are found in greatest abundance 

 near the soil surface, especially in the upper 15 

 cm (6 in), but occasional isolates can be 

 obtained at depths of a meter (yard) or more. 

 Protozoa do not constitute a major part of soil 

 biomass. but in some highly productive regions 

 such as forest litter, the protozoa are a signifi- 

 cant food source for the microinvertebrates, 

 with a biomass that may reach 20 g/m- of soil 

 suiface area there. 



