Ecology and Evolutionary Biology.

Chair: Clifford Ochs, University of Mississippi 

Vicechair: David Beckett, University of Southern Mississippi

THURSDAY MORNING

Lake View I

9:00 FERMENTATION ABILITY OF SACCHAROMYCES CEREVISIAE AND ZYMOMONAS MOBIL IS UTILIZING VARIOUS SUGARS PRESENT IN AN ACID HYDROLYZATE

Valerie O'Bannon *, Yi Zhang, Kui Zeng, Ken Lee, Maria Begonia, and Huey-Min Hwang, Jackson State University, Jackson, MS 39217

An alternative energy source could be found in microbial fermentation of the sugars present in the acid stream derived from agricultural biomass treated with acid hydrolysis. The determining factor in the production of ethanol from biomass is finding a suitable microbe. The microorganism must be tolerant to acidic conditions and able to ferment various hexose and pentose sugars. Saccharomyces cerevisiae and Zymomonas mobilis are microbes that can ferment various sugars and survive in acidic conditions. The purpose of this study is to determine the ability of Saccharomyces cerevisiae and Zymomonas mobilis to ferment sugars present in an acid hydrolyzate achieved by treating southern pine sawdust with [H.sub.2][SO.sub.4]. Five-day old cultures of Saccharomyces cerevisiae (ATCC #765) and Zymomonas mobilis (ATCC #31821) were added to fermentation media containing 0.5% of glucose, mannose, xylose or arabinose at 1:10 ratio. The samples were incubated at 30[degrees]C under anaerobic or aerobic conditions for 24 and 48 hours. Ethanol yield was measured by gas chromatography. Results showed that both Saccharomyces cerevisiae and Zymomonas mobilis could ferment glucose (0.3-0.5% ethanol yield) anaerobically or aerobically at virtually the same rate. Saccharomyces cerevisiae but not Zymomonas mobilis could ferment mannose under both anaerobic and aerobic conditions (0.3% ethanol yield). Saccharomyces cerevisiae and Zymomonas mobilis fermented xylose and arabinose with ethanol yield of 0.1%. This research was funded by DE-FG02-00ER45830 through DOE/EPSCoR program.

9:15 ALL YOUEVER WANTED TO KNOW ABOUT PIMPLEBACKS: AGE AND GROWTH IN A FRESHWATER MUSSEL

Erica Brantley *, Ann Philippi, and Melvin Warren, University of Mississippi, University, MS 38677

Freshwater mussels can be found on every continent except Antarctica. There are over 300 species of freshwater mussels that occur in North America, the most diverse freshwater mussel fauna on Earth. The presence of freshwater mussels indicates a balanced ecosystem because mussels are longlived, sedentary, benthic (bottom-dwelling) filter feeders, and are dependent on particular fish species to complete their reproductive cycle. This paper discusses species diversity and the age and growth rates of the pimpleback mussels in the Little Tallahatchie River of Mississippi. My research is based upon pimpleback mussels that are <5 years old. The purpose of this paper is to determine: (1) what species are present at two sites and does the species composition differ between sites; (2) does the age frequency distribution differ between sites, and (3) in mussels <5 years old, how does growth rate differ between sites, and with age.

9:30 COMMUNITY COMPOSITION OF CHIRONOMIDS IN SANDY SUBSTRATES IN THREE BLACKWATER STREAMS IN SOUTHERN MISSISSIPPI

Robert C. Fitch * and David C. Beckett, University of Southern Mississippi, Hattiesburg, MS 39406

The majority of streams in Mississippi have sand bottoms. In this study we investigated the larval chironomid (Diptera: Chironomidae) composition in the spring and summer in three sandy-bottomed blackwater streams located in southern Mississippi. The principal objective of this study was to describe how the chironomid communities in sand substrates varied among sites within a stream, as well as among streams. We were also interested in seasonal changes in chironomid communities. Most of the animal biomass collected from sandy substrates is in the form of relatively small invertebrates, including the chironomids. In all sites the most common chironomid larvae was Rheosmittia sp., which accounted for 50-90% of the chironomids collected. Rheosmittia sp. is a very small chironomid and is an obligate sand dweller in streams and rivers. The mean density of Rheosmittia sp. from the spring data in Black Creek is approximately 133,000 individuals/[m.sup.2] in sandy substrate. Based on evidence from our laboratory, thi s genus of chironomid dominates sand substrates from streams of the size investigated in this study up to and including the lower Mississippi River. Other chironomid taxa found in the present study included Polypedilum scalaenum group, P. halterale group, Paracladopelma sp., and Stictochironomus sp. In addition to characterizing the invertebrate fauna of sand substrates, we plan to determine if these communities will serve as indicators of pollutional disturbance.

9:45 FIXED ACTION PATTERNS IN THE COURTSHIP BEHAVIOR OF THE SALTICID SPIDER, ZYGOBALL USNER VOSUS (PECKHAM) WITH AN EVALUATION OF CRANE'S HYPOTHESIS OF SIMULTANEOUS "FEAR" AND SEXUAL DRIVES IN THE COURTSHIP OF JUMPING SPIDERS

John D. Davis, St. Andrews Episcopal Middle School, 370 Old Agency Road Ridgeland, MS 39157

The Jumping Spiders (Salticidae) are a large and taxonomically-confused group of visually oriented spiders. Crane (1949) has suggested that the study of ritualized behavior patterns may be useful in establishing evolutionary relationships within this family. Crane also suggests that the complex courtship behaviors of jumping spiders arose from conflicting "fear" and sexual drives, resulting in an approach-avoidance gradient in the movements of courtship rituals. Using slow-motion 16 millimeter filming and frame by frame analysis, complete courtships by five different pairs were broken down into fixed action patterns which were then statistically treated for variation. Quantitative descriptions of fixed action patterns and their variation have not been published for this species and are the first part of a detailed study of such behaviors in the genus Zygobailus. Comparison of the first and final ten fixed action components in five successful courtships do not support Crane's approach-avoidance gradient model of salticid courtship.

10:00 Break

10:15 ROOST FIDELITY OF RAFINESQUE's BIGEARED BAT, CORYNORHINUS RAFINESQUII, IN SOUTHERN MISSISSIPPI

Austin W. Trousdale* and David C. Beckett, University of Southern Mississippi, Hattiesburg, MS 30406

We used banding and radiotelemetry to evaluate fidelity of Rafinesque's big-eared bat, Corynorhinus raflnesquii, to natural and manmade roosts. We captured bats that we had located during surveys of bridges and abandoned buildings in DeSoto National Forest in southeastern Mississippi. Of 104 bats banded between July 2000 and September 2002, 34 individuals were recaptured, most of them at their original site of capture. Twenty-one bats (7 males, 14 females) have thus far demonstrated long-term fidelity to specific roosts, that is, they were found at the same sites [greater than or equal to] 3 months after their initial capture. Short-term fidelity (measured in days) was assessed for 14 radiotagged bats. Males tended to use manmade structures (e.g., abandoned houses) and exhibit high fidelity to these sites, whereas most females used trees and showed lower fidelity to their roosts. Although long-term fidelity to roosts was pronounced in some individuals, data suggest that roost lability is often practiced by the species (particularly so by females) during short term periods.

10:30 SURVEY OF SALAMANDERS IN MISSISSIPPI LIMESTONE CAVES

David C. Beckett*, John G. Himes, and Austin W. Trousdale, University of Southern Mississippi, Hattiesburg, MS 39406

Mississippi's largest and best-developed limestone caves are in a rock unit called the Vicksburg Group (VG), which extends near the surface as a narrow belt east to west from Wayne County to Hinds County. The caves of Mississippi have received little scientific attention; the only comprehensive effort to survey caves in Mississippi took place in the early 1 970s. During 2000-2002 we surveyed for salamanders in the larger limestone caves of Mississippi, all within the VG. We found a total of four species: Plethodon mississippi was the most abundant, followed by Eurycea guttolineata, Eurycea cirrigera, and Desmognathus fuscus. Three species (P. mississippi, E. cirrigera, and E. guttolineata) were present in Pitts Cave, the largest known cave in Mississippi. We did not find Pseudotriton montanus flavissimus in any of the caves, and question the validity of an investigator's statement made ca. haIfa century ago, that "it is one of the most numerous salamanders in Miss. limestone caves." The composition of salaman ders we found is similar to that found by investigators in the earlier survey, conducted almost thirty years ago.

10:45 A PRELIMINARY REPORT ON IDENTIFYING CNIDARIANS USING MOLECULAR TECHNIQUES

Brian R. Kreiser*, Richard L. Darden, and Brian D. Ortman, University of Southern Mississippi, Hattiesburg, MS 39406

A challenge faced by many ecological studies in the marine environment is obtaining accurate identifications of morphologically cryptic species or their life-history stages. In this project, we are developing molecular markers to identify various cnidarian groups. The basic protocol involves using the polymerase chain reaction (PCR) to amplify a specific target gene. Identifications are made by screening these PCR products using a variety of techniques including size variation, restriction fragment length polymorphisms (RFLPs) and selective amplification by PCR. We are refining this approach with two goals in mind. First, we are using this technique to identify individual polyps. Second, we are optimizing these techniques for use in the identification and quantification of cnidarian species present in ballast water.

11:00 Divisional Business Meeting

11:15 Divisional Poster Session

A STUDY OF PHOTOINDUCED ECOTOXICITY OF 6-AMINOCHRYSENE TO MICROBIAL ASSEMBLAGES AND RECOVERY OF THEIR HETEROTROPHIC ACTIVITY

Baoying Zheng *, Kui Zeng, Yi Zhang, Huey-Min Hwang, and Hongtao Yu, Jackson State University, Jackson, MS 39217

6-Aminochrysene (6-AC), a slightly water-soluble polycyclic aromatic hydrocarbon (PAH) compound, has been of great concern due to ecotoxicity caused by the parent compound and its photoproducts. Microbial assemblages in a river water sample were used to determine the ecotoxicity of 6-AC and its photoproducts. The microbial bioassay includes spread plate counting and microbial mineralization of (14) C-D-glucose. In dark, at 6-AC concentration of 10 [mu]M, bacterial viability was not affected and heterotrophic activities were inhibited by 42% and 40% respectively after 36 and 120 min. Under sunlight, exposure to 6-AC photoproducts inhibited bacterial viability and heterotrophic activities by 62%, 93%, and 74%, 74%, after 36 and 120 min respectively. Therefore, photoinduced toxicity of 6-AC to microbial assemblages was observed in this study. The same methods were used to study the recovery of heterotrophic activity of microbial assemblages in the river water after 36 min-exposure to 6-AC in sunlight. There was no obvious recovery of heterotrophic activities after two and four hours, and about 20% was recovered overnight. For the microbial assemblages viability test, in the dark about 12.6% and 100% were recovered after four hours and overnight respectively; under room light, about 3.5% and 71.8% were recovered correspondingly. This research was supported by: (1) NIH-RCMI 1G12RR1245901 and NIH-SCORE S06GM08047 (to JSU); (2) U.S. Department of the Army #DAAD 19-01-1-0733 to JSU; and (3) U.S. Department of Energy #DE-FG02-00ER45830 with subcontract to JSU.

PRODUCTION OF INDOLE-3-ACETIC ACID (IAA) IN FRESHWATER WETLANDS AND PHYLOGENETIC EVALUATION OF INDOLE-3-PYRUVATE DECAR-BOXYLASE (IPDC)

Dinesh Talreja * and Lydia Halda-Alija, University of Mississippi, University, MS 38677

Production of indole-3-acetic acid (IAA), a key physiological feature of heterotrophic and enteric plant growth-promoting (PGP) rhizosphere assemblages associated with freshwater macrophyte Juncus effusus L. was examined using classical microbiological methods over a period of three years. Up to 85% of PGP rhizobacteria produced IAA. The cultivated enteric bacteria as determined on MacConkey agar were an average 3.2 x [10.sup.3] CFU [gm.sup.-1] dry soil in the vegetated sediments as compared to 3.9 x [10.sup.1] CFU [gm.sup.-1] dry soil in the unvegetated sediments. Interestingly, enteric bacteria produced IAA even when tryptophan was not added to the medium. API20E and 16SrRNA sequencing assigned most of the enteric isolates to Enterobacter cloacae, Enterobacter agglomerans, and Klebsiella oxytoca. Indole-3-decarboxylase (IPDC) is a key enzyme in IAA synthesis in these bacteria. A ClustalX-generated sequence analysis showed the occurrence of similar sequences for IPDC in diverse microorganisms and plants like Arabidopsis thaliana, Fragaria anannasa, Pisum sativum, and Zea mays. A neighbor-joining (NJ) tree was created using the distance method. The phylogenetic tree of the IPDC sequences that originate from different plant and microbial species was supported by a very high bootstrap value (more than 98%). Our results indicate that the number of enteric bacteria was significantly higher (p <0.05) in vegetated sediments as compared to unvegetated sediments which was due to the rhizosphere effect (R/S = 82.1).

RECOVERY AND ENUMERATION OF BACTERIA AND FUNGI FROM SOILS CONTAMINATED WITH LEAD AND CADMIUM

Diahanna Hackett*, Darla Gilliard*, Ashley Davis*, Bridgette Matthews*, Afrachanna Butler, Maria Begonia, and Gregorio Begonia, Jackson State University, Jackson, MS 39217

Little is known about in situ microbial community responses to heavy metal stress. Such study is necessary before remediation of heavy metals can be effectively pursued. The primary objective of this study was to evaluate the effects of soil-applied lead (Pb), cadmium (Cd) and chelates on soil microbial populations. In this study, soils that were previously amended with various metal and chelate concentrations and planted with wheat for six weeks were used after they have been cleaned of debris, air-dried, and sieved to the desired particle size. An appropriate volume (0.1 ml) of each serially diluted soil sample was spread plated on tryptic soy agar for bacteria and on rose bengal Martin's agar for fungi. Results showed that both lead and cadmium differentially affected both soil bacterial and fungal populations. Generally, soil bacteria were tolerant to all levels of soil-applied Pb. Soil fungi were tolerant up to 1,000 mg Pb/kg, but were severely inhibited at 2,000 mg Pb/kg dry soil. Soil bacterial populat ions were severely reduced by Cd, especially at the two highest concentrations (1,000 and 2,000 mg Cd/kg dry soil) in combination with the highest EGTA treatment (5.0 mmol/kg dry soil). Soil fungi were tolerant to both Cd and EGTA as evidenced by their similar or higher numbers compared to those present in the control treatments. The resistance of the soil bacteria and fungi to soil-applied lead and cadmium indicates that these microorganisms have resistance mechanisms to deal with metal toxicity.