Geology topics

Patricia M. Mazik

Publications and source records attributed to Patricia M. Mazik.

21 records · Page 2Linked to original sources

USGS2013

The temperature-productivity squeeze: Constraints on brook trout growth along an Appalachian river continuum

We tested the hypothesis that brook trout growth rates are controlled by a complex interaction of food availability, water temperature, and competitor density. We quantified trout diet, growth, and consumption in small headwater tributaries characterized as cold with low food and high trout density, larger tributaries characterized as cold with moderate food and moderate trout density, and large main stems characterized as warm with high food and low trout density. Brook trout consumption was highest in the main stem where diets shifted from insects in headwaters to fishes and crayfish in larger streams. Despite high water temperatures, trout growth rates also were consistently highest in the main stem, likely due to competitively dominant trout monopolizing thermal refugia. Temporal changes in trout density had a direct negative effect on brook trout growth rates. Our results suggest that competition for food constrains brook trout growth in small streams, but access to thermal refugia in productive main stem habitats enables dominant trout to supplement growth at a watershed scale. Brook trout conservation in this region should seek to relieve the “temperature-productivity squeeze,” whereby brook trout productivity is constrained by access to habitats that provide both suitable water temperature and sufficient prey.

West Virginia↗

USGS2012

Brook trout movement in response to temperature, flow, and thermal refugia within a complex Appalachian riverscape

We quantified movements of brook trout Salvelinus fontinalis and brown trout Salmo trutta in a complex riverscape characterized by a large, open-canopy main stem and a small, closed-canopy tributary in eastern West Virginia, USA. Our objectives were to quantify the overall rate of trout movement and relate movement behaviors to variation in streamflow, water temperature, and access to coldwater refugia. The study area experienced extremely high seasonal, yearly, and among-stream variability in water temperature and flow. The relative mobility of brook trout within the upper Shavers Fork watershed varied significantly depending on whether individuals resided within the larger main stem or the smaller tributary. The movement rate of trout inhabiting the main stem during summer months (50 m/d) was an order of magnitude higher than that of tributary fish (2 m/d). Movement rates of main-stem-resident brook trout during summer were correlated with the maximum water temperature experienced by the fish and with the fish's initial distance from a known coldwater source. For main-stem trout, use of microhabitats closer to cover was higher during extremely warm periods than during cooler periods; use of microhabitats closer to cover during warm periods was also greater for main-stem trout than for tributary inhabitants. Main-stem-resident trout were never observed in water exceeding 19.5°C. Our study provides some of the first data on brook trout movements in a large Appalachian river system and underscores the importance of managing trout fisheries in a riverscape context. Brook trout conservation in this region will depend on restoration and protection of coldwater refugia in larger river main stems as well as removal of barriers to trout movement near tributary and main-stem confluences.

West Virginia↗

USGS2008

Microhabitat use by brook trout inhabiting small tributaries and a large river main stem: Implications for stream habitat restoration in the central Appalachians

Brook trout (Salvelinus fontinalis) habitat restoration is needed across a range of stream sizes; however, studies quantifying brook trout habitat preferences in streams of differing sizes are rare. We used radio-telemetry to quantify adult brook trout microhabitat use in a central Appalachian watershed, the upper Shavers Fork of the Cheat River in eastern West Virginia. Our objectives were to: 1) quantify non-random microhabitat use by adult brook trout in the Shavers Fork main stem (drainage area = 32 km2) and an adjacent tributary, Rocky Run (drainage area = 7 km2); and 2) construct stream-specific habitat suitability curves (HSCs) for four important microhabitat variables (depth, average current velocity, maximum current velocity within one meter, and distance to cover). Brook trout used a subset of available microhabitats in both the main stem and Rocky Run: trout tended to occupy microhabitats that were deeper, higher velocity, and closer to cover than expected by chance alone. Although specific microhabitat values differed between the main stem and tributary populations, the overall patterns in brook trout microhabitat use were consistent regardless of stream size. Habitat suitability curves were constructed based on brook trout microhabitat use and will be used to design and monitor the effectiveness of future habitat restoration efforts in the Shavers Fork watershed. Our results suggest that habitat enhancement projects that increase the availability of deep, high velocity microhabitats adjacent to cover would benefit brook trout in both small tributaries and larger river main stems.

Proceedings of the Southeastern Association of Fis↗