David G. Argent

Predicting freshwater fish distributions using landscape-level variables

Abstract Management and conservation of aquatic systems requires the ability to identify species’ historical, current, and potential distributions. We explored how a geographic information system can be used in conjunction with a few broad landscape variables to provide watershed-scale information useful for identifying diverse aquatic areas and predicting potential fish habitat. We developed species habitat profiles for all fish species that are known to occur in Pennsylvania. Five landscape variables were used to characterize a species’ habitat profile to predict its statewide distribution: presence in a major drainage basin, presence in a physiographic region, median watershed slope, level of watershed disturbance, and watershed-stream size. Each of these variables was referenced to a small watershed boundary. Using these variables, we predicted a species potential habitat range. Distribution maps that we generated were then compared to known distributions with an average accuracy of 73%. While many collections have been made in Pennsylvania over the last 50 years, we determined that many areas still remain unexplored as potential sampling locations. Among those fishes whose predicted distribution was less than the actual sampled distribution, four receive special protection in Pennsylvania and one is federally endangered. Moreover, we determined that small watersheds (1:24,000 scale) in the Allegheny River drainage, in the Pittsburgh Low Plateau Section, of small size (3–4 order), with moderate slope (2–4%), and moderate watershed disturbance (25–75%) have the highest fish species richness. Our results should facilitate the conservation of fish species and our technique should be easily repeatable in other geographic areas.

Fish assemblage changes in relation to watershed landuse disturbance

Fish assemblage collections were assessed in sub-watersheds containing various land use types to relate overall biotic condition to patterns of watershed disturbance and to the influence of introduced fishes. Four hundred historical and contemporary fish collections were analyzed in conjunction with land use and land cover data among 200, first- through fourth-order sub-watersheds across Pennsylvania. A high degree of collinearity among several land use types and the presence of non-indigenous fishes was determined, indicating multiple anthropogenic influences. Significant relationships were found between various land use types and the Jaccard coefficient of similarity, the primary index used to evaluate changes between fish collections, across all major drainages. In general, the Jaccard coefficient of similarity increased to a value of one as the percentage of forested land increased, while the Jaccard coefficient of similarity decreased as percentages of agricultural and urban land increased. Sub- watersheds that showed declines in species richness had significantly higher percentages of agricultural and developed land, while those sub-watersheds with higher amounts of forested land appeared relatively stable. Seventy-percent of those species that experienced declines were either insectivores or benthic insectivores. The largest increases among the fish guilds occurred within the insectivore-piscivore group. We conclude that land use influences at the sub-watershed scale and the introduction of non-indigenous fishes have had a significant influence on fish community composition.

Efficiency and Selectivity of Gill Nets for Assessing Fish Community Composition of Large Rivers

Abstract To evaluate the efficiency and selectivity of gill netting for assessing fish biodiversity in the upper Ohio River system, we compared the efficiency of five gill-net types for sampling large-bodied fishes (adult total length greater than 250 mm) during fall 2001 and spring and fall 2002. Mesh sizes ranged from 3.8 cm to 14 cm (bar measure). We set the gill nets in selected pools of the Allegheny, Monongahela, and Ohio rivers 186 times over three seasons for a total of 1,644 net-hours. Nets were attached to a variety of structures, including trees and rootwads, bridge pylons, lock and dam chambers, and channel marker buoys. Nets were fished from late evening to first light, and all fish captured were identified, enumerated, and released. A total of 823 individuals representing 30 species or hybrids were captured. All net types captured common carp Cyprinus carpio and flathead catfish Pylodictis olivaris, but we captured a significantly greater diversity of fishes in graded-mesh gill nets with sma...

Ichthyofauna of the Monongahela River Basin in Pennsylvania: A Contemporary Evaluation

ABSTRACT By the 1900s, the ichthyofauna of Pennsylvanias Monongahela River basin was decimated by a combination of discharges from industrial, coal extraction, and municipal sources. Over the past half-century, water quality improvements resulting fiom federal and state mandates have initiated a continuing recovery of fish populations throughout the mainstem. We compiled the results of recent (2003–06) collections from the river and its tributary network by a number of state, federal, and academic agencies employing a variety of gear. The combined sampling methods yielded 32,999 fishes on the mainstem, representing 14 families and 64 species/hybrids, while 6,825 fishes representing 10 families and 51 species/hybrids were captured from the tributaries. Tributary species richness ranged from 24 to 0 concomitant with declining water quality. Members of the families Ictaluridae and Cyprinidae dominated mainstream communities, while the Percidae and Cyprinidae were prevalent in its tributaries. Twenty-two species were captured only from the Monongahela mainstem, while 11 were unique to its tributaries and 39 were cosmopolitan. Overall, the Monongahela Basin ichthyofaunal complement currently numbers 75 species/hybrids.

Development and Application of an Index of Biotic Integrity for Fish Communities of Wadeable Monongahela River Tributaries

ABSTRACT We developed an index of biotic integrity (IBI) to assess the health of fish communities inhabiting low-order tributaries of the Monongahela River in Pennsylvania. Environmental stressors observed were urbanization, agriculture, raw and treated sewage discharges, net alkaline mine drainage, and acid mine drainage (AMD). Species richness ranged from zero in streams impacted by AMD and/or untreated sewage to 24 in our reference stream. Our IBI classified the majority (>90%) of streams in this region as significantly stressed, receiving qualitative evaluations of “fair” to “very poor.” Moreover, of the 4,090 fishes collected, only four species representing 2% of the total number collected were classified as intolerant to pollution.

Fish Assemblage Connectivity in the Monongahela River Basin

Abstract Tributary and mainstem corridors represent important fish-connectivity avenues in large riverscapes. We evaluated the connectivity of 40 Monongahela River tributaries in southwestern Pennsylvania and their respective mainstem junctions using a variety of gears. Twelve tributaries were so fragmented by physical and water-quality impediments, comparisons could not be made. Among the 28 remaining tributaries, classified as adventitious (lst–3rd order) or ordered (4th–5th order), we evaluated fish communities using the Jaccard coefficient of similarity, a cluster analysis, and a Venn diagram. Adventitious tributaries shared 82% of their total faunal complement with ordered tributaries and 29% with the mainstem, while 70% of the ordered ichthyofauna was common to the mainstem. The ichthyofauna of the adventitious tributary network was more distinct and isolated from the mainstem than that of ordered tributaries. In fragmented riverscapes such as this, islands (tributaries) of biodiversity may warrant special protection.

Movement and Habitat Use of Stocked Juvenile Paddlefish in the Ohio River System, Pennsylvania

Abstract In 2002 and 2003 we released a total of 66 hatchery-reared, juvenile paddlefish Polyodon spathula (249–318 mm eye-to-fork length) in Pennsylvanias upper Ohio River system and tracked them with radiotelemetry in two different pools of the Ohio and Allegheny rivers to determine (1) poststocking survival, (2) whether release site influences survival, (3) dispersal distance and direction of movement, and (4) habitat selection. Survival was fair (mean = 78% in 2002 and 67% in 2003) for 0.23–0.43-kg paddlefish after 9 weeks. In 2003, fish stocked in the upstream half of the pool had a greater survival (100%) after 63 d than those stocked in the downstream half (44%). Within 4 d of stocking, 77% of juvenile paddlefish were located in tailwaters, and fish found these habitats regardless of stocking location. Habitat measurements at all postdispersal locations had median depths of 5.2 and 6.1 m in 2002 and 2003, respectively, and median near-surface velocities of 0.17 and 0.12 m/s. Fish selected tailwate...

Seasonal Use of Recently Fenced Agricultural Riparian Habitat by Avifauna in Pennsylvania

Abstract Streambank fencing is increasingly used to exclude livestock from riparian corridors and to enhance biological communities. Our study examined vegetative change and avian-community use of recently fenced agricultural habitat. We conducted strip-transect surveys to census bird communities, line-transect and plot surveys to assess vegetation, and intensive nest monitoring to gauge use and reproductive success across 12 fenced riparian sites in southwestern Pennsylvania. Selected sites varied in age from 3 to 8 years since fencing and averaged 21 m in width. We found avian use was significantly greater in spring than in fall across our fenced sites. We determined that canopy cover, shrub cover, and herbaceous ground cover could predict various attributes of the avian community present within the fenced riparian areas. Our results also suggest that the avian community has greater species richness within sites containing greater habitat complexity, and that these sites are important breeding and nesting areas. Among the 145 nests monitored, 38% successfully fledged young. We found no differences in distance to corridor edge between successful nests and nests that failed. Our study confirms that riparian renovation efforts do have conservation value for both migratory and resident birds.

Use of the Coefficient of Community Loss (I) to Assess Cultural Stresses on Monongahela River Tributary Fish Communities

ABSTRACT We utilized a single metric, the coefficient of community loss (I) to assess the health of fish communities inhabiting 27 low-order Monongahela River tributaries in Pennsylvania. All streams were sampled during summers of 2003 and 2004 utilizing two-pass back-pack electrofishing from the mouth extending 200 m upstream. Environmental stressors observed in and on-stream were habitat alteration and non-point source discharges due to urbanization and agriculture along with point-source discharges of raw and treated sewage, net alkaline mine drainage, and acid mine drainage (AMD). Species richness and I-metric scores in streams impacted by major AMD and/or untreated sewage were 0 and α, respectively. While those exhibiting minimal cultural stress had species richness totals and I-metric scores of 24 and 0.24, respectively. Values of I were negatively correlated with index of biotic integrity scores (-0.951), suggesting that I could provide a rapid comprehensive assessment of the relative health of fish communities within a major watershed.

Potential impacts of climate change on brook trout (Salvelinus fontinalis) populations in streams draining the Laurel Hill in Pennsylvania

To establish a baseline for assessment of climate change effects on populations of brook trout (Salvelinus fontinalis) in southwestern Pennsylvania, we surveyed a collective of headwater streams for fish population status and the development of annual air and stream temperature profiles. The 20 streams selected, 10 located on each facing slope of an anticlinal fold on the Appalachian Plateau, Laurel Hill, historically supported self-sustaining brook trout populations. In these watersheds, anthropogenic activity was minimal and riparian canopy intact. Three, from each facing slope along with the cool-water receiving stream for the respective tributary network, received riparian air and in-stream temperature data loggers. Data loggers were retrieved after one calendar year and temperature profiles for all eight streams downloaded. From these, we analyzed the air/stream temperature relationship for the calendar year and during the growing season for each headwater stream. Wild brook trout were present in all streams along with mottled sculpins (Cottus bairdi) and occasional representatives of six other species. Streams varied in the number of days experiencing thermal stress for brook trout (>18°C) ranging from a minimum of 0 to a maximum of 67, and the slope of each individual air/in-stream temperature relationship correlated with temporal stress. Local differences in riparian cover and groundwater inputs appear to be responsible for the deviation from climate model predictions and suggest resiliency in these headwater ecosystems. Of more immediate concern is the potential for the interruption of connectivity among tributary networks. Thermal profiles of the cool-water receiving streams revealed air temperature as a strong correlate of in-stream temperature. A warming climate may progressively constrict these avenues of gene flow among resident brook trout tributary populations leading eventually to their genetic isolation.