Department of Fish and Wildlife Conservation
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- Germination Response of Legume Seeds Subjected to Moist and Dry HeatMartin, R. E.; Miller, R. L.; Cushwa, Charles T. (Ecological Society of America, 1975)Prescribed burning is used in southeastern USA to promote growth of leguminous plants which produce seed important as quail food. These seed are characterized by a hard seed coat and the ability to remain dormant but viable for a long time. This study was conducted to determine the effect of heat on germination of seed from several of these legume species. Seeds of 18 species and two varieties were subjected to moist and dry heat treatment. Moist heat increased germination in eight species and two varieties, and dry heat increased germination in seven species and two varieties.
- Offshore distribution of alewife, alosa-pseudoharengus, and blueback herring, alosa-aestivalis, along the Atlantic coastNeves, Richard (National Marine Fisheries Service Scientific Publication Office, 1981)This study of the offshore distribution of alewife, Alosa pseudoharengus, and blueback herring, A. aestivalis, in the Atlantic Ocean was based on catch data collected over the 16-year period 1963-78 during bottom trawl surveys by the National Marine Fisheries Service and its predecessor agency. All catches of the two species were made where bottom water temperatures ranged from 2° to 17° C, and catches were most frequent at bottom temperatures between 4° and 7° C. Most catches ofboth species were made at stations where depth was less than 100 m. Chi-square analyses indicated that alewives were captured significantly more often than expected in the 56 to no m depth stratum and blueback herring in the 27 to 55 m stratum (P<0.01).During summer and autumn, all catches of the two species were confined to the region north of latitude 40° north in three general areas: Nantucket Shoals, Georges Bank, and the perimeter of the Gulf of Maine (especially in autumn along the northwestern edge of the gulf), Winter catches were between latitude 40° and 43° north, and spring catches were distributed throughout the continental shelf area between Cape Hatteras, N.C., and Nova Scotia. Previous studies on juveniles, food of adults, and differences in time of capture during National Marine Fisheries Service surveys indicated that these species are vertical migrators, apparently following the diel movements of zooplankton in the water column.
- The case for environmental moderation (or why people who live in recycled bottles shouldn't throw stones)Nielsen, Larry A. (University of California Press, 1981)I am an environmentalist. I turn off the water while I brush my teeth, and I only buy beer in returnable bottles. I started a paper-recycling system in my department at the university. And, as soon as I can afford it, I'm going to trade my roomy, comfortable station wagon for a car that gets conscience-soothing gas mileage. Perhaps, though, I'm not an environmentalist at all. Perhaps I'm just overly conscientious. I use my turn signals when no one is around to notice. I always flush in public toilets, and I contribute a dime every time I get coffee from the departmental pot (well, almost every time).
- A Comparison of Principal Components from Real and Random DataStauffer, Dean F.; Garton, E. O.; Steinhorst, R. K. (Ecological Society of America, 1985)We compared principal components derived from sets of real data with dimensions of 120 x 7, 120 x 4, 150 x 11, 150 x 8, 150 x 5, 454 x 12, 454 x 8, and 454 x 5, to those from sets of randomly generated data of corresponding size. Principal components from subsets of 25, 50, 75, and 100 observations from the 120- and 150-observation data sets and those from subsets of 25, 50, 75, 100, 150, 200, 300, and 400 observations from the 454-observation data sets were compared. Percent variance association with components from real data was relatively constant over all sample sizes; percent variance decreased with larger samples of random data. A bootstrap method was used to develop standard error estimates on percent variance and percent of remaining variance associated with components from real data. Percent of remaining variance associated with the first four components from real data was significantly higher than analogous components from random data.
- Assessment of Sampling Stability in Ecological Applications of Discriminant AnalysisWilliams, B. K.; Titus, K. (Ecological Society of America, 1988-08)A simulation study was undertaken to assess the sampling stability of the variable loadings in linear discriminant function analysis. A factorial design was used for the factors of multivariate dimensionality, dispersion structure, configuration of group means, and sample size. A total of 32 400 discriminant analyses were conducted, based on data from simulated populations with appropriate underlying statistical distributions. Results from the simulations suggest that minimum sample sizes must exceed multivariate dimensionality by at least a factor of three to achieve reasonable levels of stability in discriminant function loadings. However, the requisite sample size would vary with respect to each of the design factors and, especially, with the overall amount of system variation. A review of 60 published studies and 142 individual analyses indicated that sample sizes in ecological studies often have met that requirement. However, individual group sample sizes frequently were very unequal, and checks of assumptions usually were not reported. We recommend that ecologists obtain group sample sizes that are at least three times as large as the number of variables measured.
- Species-Area Relationship for Stream FishesAngermeier, Paul L.; Schlosser, I. J. (Ecological Society of America, 1989-10)We sampled riffles and pool habitats of small streams in Minnesota, Illinois, and Panama to examine variation in species-area relationships within and between the respective fish faunas. For six of the seven steams studies, habitat lume was a better predictor of species richness than was habitat area, and number of individuals was a better predictor of species richness than habitat volume. Slopes of species-volume relationships were similar among regions, but the number of species per unit volume was greater in Panama. Multiple regression analyses indicated that knowledge of habitat complexity and volume did not enhance appreciably the capability of linear models to predict species richness from number of individuals in the sample. These results support the hypothesis that species-area relationships may often be epiphenomena stemming from the more comprehensive community "samples" intercepted by larger habitat patches. Although number of individuals was the best single predictor of species richness, habitat structure and type clearly influenced species' distributions in some streams, thereby indicating that species-area relationships were not strictly sampling phenomena. An index of habitat complexity based on depth, current, and bottom type was correlated with species richness in two Panama streams. Also, the abundance of individual species was more likely to be correlated with habitat volume in Panama than in Illinois or Minnesota, and species relative abundances were more similar between years in Panama than in Illinois or Minnesota streams, especially in pools. These patterns suggest that in streams subject to strong seasonal and annual environmental variation, habitat features are poorer predictors of fish distribution and abundance than in streams subject to less environmental variability. We speculate that annual variability in reproductive success and harsh winters interact to maintain imbalance between the fish assemblages and their habitat in Minnesota. Weak relationships between species richness and habitat volume or complexity may be indicative of population variability and the predominance of extinction/recolonization processes in community organization.
- Development and Analysis of an Energetics-Based Model for Trout Populations in Appalachian StreamsMeyer, Kelly J.; Orth, Donald J. (Virginia Tech, 1990-10)
- James River Mainstem Investigation: Recreational UseGarman, Greg C.; Smock, Leonard A.; Nielsen, Larry A.; Orth, Donald J.; King, Mark A.; Stanovick, John J. (1991-07)
- James River Mainstem Investigation: Executive SummaryGarman, Greg C.; Smock, Leonard A.; Nielsen, Larry A.; Orth, Donald J.; King, Mark A.; Stanovick, John J. (1991-07)
- James River Mainstem Investigation: Fisheries Yield ModelGarman, Greg C.; Smock, Leonard A.; Nielsen, Larry A.; Orth, Donald J.; King, Mark A.; Stanovick, John J. (1991-07)
- Ospreys Use Bald Eagle Nests in Chesapeake Bay AreaTherres, Glenn D.; Chandler, Sheri K. (Raptor Research Foundation, 1993)Ospreys (Pandion haliaetus) and Bald Eagles (Haliaeetus leucocephalus) share similar breeding habitat in the Chesapeake Bay area and elsewhere. The nests of these species are similar in size and appearance. Ospreys typically build large stick nests in dead trees or on man-made structures (C.J. Henny et al. 1974, Chesapeake Sci. 15:125-133; A.F. Poole 1989, Ospreys: a natural and unnatural history, Cambridge Univ. Press, NY), while Bald Eagles usually build larger nests in live trees (P.B. Wood et al. 1989, J. Wildl. Manage. 53:441-449; Maryland Dept. of Natural Resources, unpubl. data). Osprey nests are usually placed in the open at the top of dead trees or structures, while Bald Eagle nests are usually beneath the tree canopy obscured from view. Both select nest sites close to large bodies of water or wetlands (J.M. Andrew and J.A. Mosher 1982, J. Wildl. Manage. 46:383-390; Poole 1989). Eagles nest earlier than Osprey; in the Chesapeake Bay area eagles are on eggs when Ospreys return in March.
- VT Fisheries Management Magazine(Virginia Tech, 1994)“A class magazine produced by students in Fisheries Management, Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University.” “Devoted to identifying fisheries management problems, uncovering their causes, and developing creative solutions.”
- VT Fisheries Management Magazine(Virginia Tech, 1995)“A class magazine produced by students in Fisheries Management, Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University.” “Devoted to identifying fisheries management problems, uncovering their causes, and developing creative solutions.”
- Ecological Monitoring in the New River Gorge National River: Analysis of Environmental Impacts from the Black Fly Pest Management ProgramVoshell, J. Reese Jr.; Orth, Donald J. (Virginia Tech, 1995-11)
- New River Gorge National River Long-Term Ecological Monitoring System User Manual: Field and Laboratory MethodsVoshell, J. Reese Jr.; Orth, Donald J.; Hiner, Stephen W.; Easton, Robert S. (Virginia Tech, 1996-08)
- VT Fisheries Management Magazine(Virginia Tech, 1997)“A class magazine produced by students in Fisheries Management, Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University.” “Devoted to identifying fisheries management problems, uncovering their causes, and developing creative solutions.”
- VT Fisheries Management Magazine(Virginia Tech, 1998)“A class magazine produced by students in Fisheries Management, Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University.” “Devoted to identifying fisheries management problems, uncovering their causes, and developing creative solutions.”
- Local vs. regional influences on local diversity in stream fish communities of VirginiaAngermeier, Paul L.; Winston, M. R. (Ecological Society of America, 1998-04)Local species richness is a function of many factors operating at multiple spatial and temporal scales. We examined stream fish communities from regions throughout Virginia to assess (1) the relative influence of local vs, regional factors on local species richness, (2) evidence for community saturation, and (3) scale dependency of regional influences. We defined regions at four spatial scales: major drainages, drainage-physiography units, hydrologic-physiography units, and sites. We used multiple regression to identify key correlates of local native and introduced diversity for each regional scale. Both local (e.g., microhabitat diversity) and regional (e.g., species richness) factors were correlated with local diversity; regional diversity was the most consistent correlate. Plots of local vs, regional native diversity were asymptotic for the three largest regional definitions, thereby suggesting community saturation. However, analogous plots for introduced species were not asymptotic; local introduced diversity was a linear function of regional introduced diversity. Introduced populations were pervasive, but less abundant locally than native populations, thereby suggesting that native species are better adapted. Overall, stream fish communities in Virginia appeared to be neither completely saturated nor freely invadable. The ability of regression models and particular independent variables to account for variation in local diversity changed considerably with regional scale. Most regional correlates of local diversity were scale dependent. The concept of hierarchical environmental filters provides a useful framework for integrating the multiple scales over which ecological processes organize communities. Retrospective analyses of the impacts of introduced species on native communities provide some insight regarding community saturation, but conclusive evidence must await studies that couple comparative and experimental approaches. Clear interpretation of regional influences on local diversity will require careful definition of regions. Comparative analyses at multiple regional scales may be the most insightful approach to understanding the complete array of processes that organize communities.