The Importance of Competition for Food Resources in the Interaction Between Brook Trout (\u3cem\u3eSalvelinus fontinalis\u3c/em\u3e) and Rainbow Trout (\u3cem\u3eSalmo gairdneri\u3c/em\u3e)

The last 80 years have seen a drastic reduction in the range of the brook trout (Salvelinus fontinalis) the only salmonid native to the Southern Appalachians. Much of this range reduction is directly correlated with increases in the range of the introduced rainbow trout (Salmo gairdneri). The purpose of this study was to determine if competition for food resources plays a significant role in this interaction. Stomach contents were obtained from sympatric and allopatric populations of brook and rainbow trout during June, July, August and September of 1987. Terrestrials comprised the majority of food items in the stomachs of adult fish from all populations, the mean percentage relative wet weight ranging from 59% in sympatric rainbow trout to 74% in sympatric brook trout. Comparisons using Schoener\u27s Index of Dietary Overlap indicated that there was significant dietary overlap between all populations during the majority of the sampling dates. Analysis of variance indicated that there were no significant differences in the mean relative weight of stomach contents of adult brook trout in sympatry or allopatry, or between adult brook trout and adult rainbow trout living in sympatry. However, the mean relative weight of stomach contents in adult rainbow trout in allopatry was significantly lower than that in adult rainbow trout in sympatry or adult rainbow in allopatry. Calculated caloric intake using the mean observed stomach values was never sufficient to meet the estimated metabolic demands of adult fish at any of the sites during any of the sampling periods, despite the fact that there seemed to be sufficient food resources in the stream drift. Fulton-type condition factors of sympatric and allopatric brook trout were not significantly different, but condition factors of sympatric rainbow trout were significantly higher than the condition factor of allopatric rainbow trout. Population estimates taken in July and October indicated all populations suffered losses in biomass as standing crops decreased from 48% in allopatric rainbow trout populations to 24% in sympatric rainbow trout populations. In summary, despite data that seemed to indicate that these populations were food limited, there was no evidence to support competition for food resources in areas where the two species coexist

Investigating Hydrologic Alteration as a Mechanism of Fish Assemblage Shifts in Urbanizing Streams

Stream biota in urban and suburban settings are thought to be impaired by altered hydrology; however, it is unknown what aspects of the hydrograph alter fish assemblage structure and which fishes are most vulnerable to hydrologic alterations in small streams. We quantified hydrologic variables and fish assemblages in 30 small streams and their subcatchments (area 8-20 km 2) in the Etowah River Catchment (Georgia, USA). We stratified streams and their subcatchments into 3 landcover categories based on imperviousness (20% of subcatchment), and then estimated the degree of hydrologic alteration based on synoptic measurements of baseflow yield. We derived hydrologic variables from stage gauges at each study site for 1 y (January 2003-2004). Increased imperviousness was positively correlated with the frequency of storm events and rates of the rising and falling limb of the hydrograph (i.e, storm flashiness ) during most seasons. Increased duration of low flows associated with imperviousness only occurred during the autumn low-flow period, and this measure corresponded with increased richness of lentic tolerant species. Altered storm flows in summer and autumn were related to decreased richness of endemic, cosmopolitan, and sensitive fish species, and decreased abundance of lentic tolerant species. Species predicted to be sensitive to urbanization, based on specific life-history or habitat requirements, also were related to stormflow variables and % fine bed sediment in riffles. Overall, hydrologic variables explained 22 to 66% of the variation in fish assemblage richness and abundance Linkages between hydrologic alteration and fish assemblages were potentially complicated by contrasting effects of elevated flows on sediment delivery and scour, and mediating effects of high stream gradient on sediment delivery from elevated flows. However, stormwater management practices promoting natural hydrologic regimes are likely to reduce the impacts of catchment imperviousness on stream fish assemblages. ?? 2005 by The North American Benthological Societ

From Duty to Right: The Role of Public Education in the Transition to Aging Societies

This paper argues that the introduction of compulsory schooling in early industrialization promoted the growth process that eventually led to a vicious cycle of population aging and negative pressure on education policy. In the early phases of industrialization, public education was undesirable for the young poor who relied on child labor. Compulsory schooling therefore discouraged childbirth, while the accompanying industrialization stimulated their demand for education. The subsequent rise in the share of the old population, however, limited government resources for education, placing heavier financial burdens on the young. This induced further fertility decline and population aging, and the resulting cycle may have delayed the growth of advanced economies in the last few decades

Diel Habitat Use by Fishes in a Blue Ridge Stream, Georgia

We determined diel habitat use by fishes in a Blue Ridge stream in Georgia using direct underwater observation on two occasions in September 1999. During both day and night sampling periods, individuals in the family Centrarchidae were most commonly found in shallow (\u3c20 cm depth) and deep (\u3e= 20 cm depth) areas with low water velocities (\u3c 10 cm.s(-1) average velocity). During the day, representatives of Cyprinidae were most common in deep areas with higher water velocities (\u3e 10 cm.s(-1) average velocity) but shifted to shallow areas with low water velocities during the night. Differences in diel habitat use by the two families are best explained by differences in predator avoidance strategies

Effects of Fright Bias on Sampling Efficiency of Stream Fish Assemblages

Relative efficiencies of three different fish sampling techniques (prepositioned area shockers, single pass electroshocking, and a combined shocking-seining method) with differing potential to induce fright bias were compared in riffle, run and pool habitats in Roanoke River, Virginia. Twenty-three species were captured by the three techniques. Of the three techniques, pre-positioned area shockers had the highest species accumulation rate in each of the three habitats sampled. The single pass electroshocking method had higher species accumulation rates than the combined technique in pools and runs, whereas the performance of the two techniques was similar in riffles. Pre-positioned area shockers also captured a higher proportion of larger, more mobile individuals than the other two techniques. Based on our results, prepositioned area shockers were the least biased of the three techniques for sampling riverine fish

The Effect of Road Crossing on Fish Movements in Small Etowah Basin Streams

Increased road construction associated with urbanization may result in fragmentation and loss offish populations in streams. In this study, we documented frequency of movement of fishes through three separate types of road-crossings (clear-span bridges, box culverts, and tube culverts) in six small streams using mark-recapture sampling. Upstream movement between areas separated by either box or tube culverts was lower than upstream movement between similar areas not separated by a road crossing. Downstream movement between areas separated by box culverts was also lower than downstream movement between areas without obstructions. Upstream and downstream movement between areas separated by clear-span bridges was generally similar to patterns of movement between areas not separated by a road crossing. Our results indicate that culverts may limit, to some degree, movements of fishes in small streams

Status of Water Quality and Biological Integrity in Major Watersheds in Bartow County, Georgia

Technical Report for Bartow County, GA

Comparing Abiotic and Biotic Parameters Within a Geologically Diverse Area (Bartow County, GA)

During the summer of 2000, we sampled twenty-two stream sites in Bartow County (Georgia) for fish, macro-invertebrates, water quality, habitat condition, and bacterial indicators as part of a county-wide watershed assessment. Three major geological regions occur within the county (to the west rocks are mainly limestone, to the north shales and sandstones, and to the east and southeast harder metamorphic rocks). Because the county is so geologically diverse yet all sites are within the same drainage basin, this data set provides a rare opportunity to examine the influence of watershed geology within a relatively small geographic area on parameters and metrics traditionally used to assess anthropogenic impacts. Principal component analysis (PCA) and other comparisons indicate that most biotic and abiotic parameters over all sites are related to one another in ways expected among sites that vary due to anthropogenic impacts. Multimetrics developed for fish and for invertebrates reflected trends along the primary PCA `water quality\u27 factor (turbidity, suspended solids, and BOD), whereas site geology did not reflect trends across this factor. As expected dissolved ions (as well as alkalinity and pH) were strongly related to watershed geology, but other less obvious water quality parameters such as nitrate were also associated with geologic location. Most individual metrics that are traditionally used to assess invertebrate and fish communities did not appear to be influenced by geology, but rather by anthropogenic habitat and water changes. In addition, differences in taxonomic composition of invertebrate communities were associated with watershed geology. Any given invertebrate community within the western limestone region was most similar (based on similarity indices of species composition) to other communities within this same region. Communities within the other two regions were not similar to western communities, but not distinctly different from each other. Because water chemistry between streams of western limestone and streams of northern shale-sandstone are more similar, geological influences on invertebrate species distribution may reflect physical stream characteristics (such as streambed morphology and substrate characteristics) rather than water chemistry. While underlying geology strongly affected many water quality parameters, biotic measures were relatively independent of these water quality effects, indicating biotic parameters are reliable in assessing degradation in a geologically diverse basin