Geology topics

Cynthia S. Loftin

Publications and source records attributed to Cynthia S. Loftin.

25 records · Page 2Linked to original sources

USGS2013

Carcass analog addition enhances juvenile Atlantic salmon ( Salmo salar ) growth and condition

Our study used historic marine-derived nutrient (MDN) delivery timing to simulate potential effects of restored connectivity on juvenile Atlantic salmon (ATS; Salmo salar ) growth and condition. Four headwater streams were stocked with ATS young of the year (YOY) and received carcass analog additions (0.10 kg·m –2 wetted area) in treatment reaches to match the timing of sea lamprey ( Petromyzon marinus ) spawning. Individual ATS mass was 33%–48% greater and standard length was 9%–15% greater in treatment reaches relative to control reaches for 4 months following nutrient additions. Percent total lipids in YOY ATS were twice as great in treatment reaches 1 month following carcass analog additions and remained elevated in treatment fish for 2 more months. Absolute growth rates, based on otolith microstructure analysis, correlated with water temperature fluctuations in all reaches and were elevated by an average of 0.07 mm·day –1 in treatment reaches for 1 month following carcass analog additions. Simulated sea lamprey MDNs increased juvenile ATS growth, which, via potential increases in overwinter survival and decreases in smolt age, may contribute to population persistence and ecosystem productivity.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2013

Landsat imagery reveals declining clarity of Maine’s lakes during 1995-2010

Water clarity is a strong indicator of regional water quality. Unlike other common water-quality metrics, such as chlorophyll a , total P, or trophic status, clarity can be accurately and efficiently estimated remotely on a regional scale. Satellite-based remote sensing is useful in regions with many lakes where traditional field-sampling techniques may be prohibitively expensive. Repeated sampling of easily accessed lakes can lead to spatially irregular, nonrandom samples of a region. Remote sensing remedies this problem. We applied a remote monitoring protocol we had previously developed for Maine lakes >8 ha based on Landsat satellite data recorded during 1995–2010 to identify spatial and temporal patterns in Maine lake clarity. We focused on the overlapping region of Landsat paths 11 and 12 to increase availability of cloud-free images in August and early September, a period of relative lake stability and seasonal poor-clarity conditions well suited for annual monitoring. We divided Maine into 3 regions (northeastern, south-central, western) based on morphometric and chemical lake features. We found a general decrease in average statewide lake clarity from 4.94 to 4.38 m during 1995–2010. Water clarity ranged from 4 to 6 m during 1995–2010, but it decreased consistently during 2005–2010. Clarity in both the northeastern and western lake regions has decreased from 5.22 m in 1995 to 4.36 and 4.21 m, respectively, in 2010, whereas lake clarity in the south-central lake region (4.50 m) has not changed since 1995. Climate change, timber harvesting, or watershed morphometry may be responsible for regional water-clarity decline. Remote sensing of regional water clarity provides a more complete spatial perspective of lake water quality than existing, interest-based sampling. However, field sampling done under existing monitoring programs can be used to calibrate accurate models designed to estimate water clarity remotely.

Maine↗

USGS2012

Mercury bioaccumulation in wood frogs developing in seasonal pools

Seasonal woodland pools contribute significant biomass to terrestrial ecosystems through production of pool-breeding amphibians. The movement of amphibian metamorphs potentially transports toxins bioaccumulated during larval development in the natal pool into the surrounding terrestrial environment. We documented total mercury (THg) in seasonal woodland pool water, sediment, litter, and Lithobates sylvaticus LeConte (Wood Frog) in Acadia National Park, ME. THg concentrations in pool water varied over the study season, increasing during April—June and remaining high in 2 of 4 pools upon October refill. Water in pools surrounded by softwoods had lower pH, greater dissolved organic carbon, and greater THg concentrations than pools surrounded by hardwoods, with seasonal patterns in sediment THg but not litter THg. THg increased rapidly from near or below detection in 1–2 week old embryos (<0.2 ng; 0–0.49 ppb wet weight) to 17.1–54.2 ppb in tadpoles within 6 weeks; 7.2–42.0% of THg was methyl Hg in tadpoles near metamorphosis. Metamorphs emigrating from seasonal pools may transfer mercury into terrestrial food webs.

Northeastern Naturalist↗

USGS2009

Effects of introduced fish on macroinvertebrate communities in historically fishless headwater and kettle lakes

Widespread fish introductions have led to a worldwide decline in the number of fishless lakes and their associated communities. Studies assessing effects of fish stocking on native communities in historically fishless lakes have been limited to high-elevation headwater lakes stocked with non-native trout. Little is known about the effect of fish stocking in historically fishless and hydrologically isolated lowland kettle lakes. We compared the effects of introduced fish on macroinvertebrate communities in kettle lakes stocked with centrarchids, salmonids, and cyprinids, and headwater lakes stocked with brook trout ( Salvelinus fontinalis ) in Maine, USA. Fish had significant effects on macroinvertebrate community structure in both lake types, with reduced species richness and abundances of taxa characteristic of fishless lakes. The effects of introduced fish were more pronounced in headwater lakes despite a less diverse fish assemblage than in kettle lakes. We attribute this to abundant submerged vegetation providing refuge from fish predation and reduced stocking frequency in kettle lakes. We assessed effects of stocking duration on macroinvertebrates in a subset of headwater lakes with known dates of trout introduction. Species richness and abundance of most taxa declined within 3 years following trout introduction; however, richness and abundance were least in lakes with long stocking histories (≥40 years). Macroinvertebrates previously identified as fishless bioindicators were absent from all stocked lakes, indicating that trout rapidly eliminate these sensitive taxa. Conservation of this historically undervalued ecosystem requires protecting remaining fishless lakes and recovering those that have been stocked.

Maine↗

USGS2007

Influence of observers and stream flow on northern two-lined salamander (Eurycea bislineata bislineata) relative abundance estimates in Acadia and Shenandoah National Parks, USA

We investigated effects of observers and stream flow on Northern Two-Lined Salamander ( Eurycea bislineata bislineata ) counts in streams in Acadia (ANP) and Shenandoah National Parks (SNP). We counted salamanders in 22 ANP streams during high flow (May to June 2002) and during low flow (July 2002). We also counted salamanders in SNP in nine streams during high flow (summer 2003) and 11 streams during low flow (summers 2001?02, 2004). In 2002, we used a modified cover-controlled active search method with a first and second observer. In succession, observers turned over 100 rocks along five 1-m belt transects across the streambed. The difference between observers in total salamander counts was not significant. We counted fewer E. b. bislineata during high flow conditions, confirming that detection of this species is reduced during high flow periods and that assessment of stream salamander relative abundance is likely more reliable during low or base flow conditions.

Maine, Virginia↗

USGS2005

Mercury bioaccumulation in northern two-lined salamanders from streams in the northeastern United States

Mercury (Hg) bioaccumulation in salamanders has received little attention despite widespread Hg contamination of aquatic ecosystems and worldwide amphibian declines. Here we report concentrations of methyl Hg (MeHg) and total Hg in larval northern two-lined salamanders ( Eurycea bislineata bislineata ) collected from streams in Acadia National Park (ANP), Maine, and Bear Brook Watershed, Maine (BBWM; a paired, gauged watershed treated with bimonthly applications (25 kg/ha/yr) of ammonium sulfate [(NH 4 ) 2 SO 4 ]) since 1989), and Shenandoah National Park (SNP), Virginia. MeHg comprised 73–97% of total Hg in the larval salamander composite samples from ANP. At BBWM we detected significantly higher total Hg levels in larvae from the (NH 4 ) 2 SO 4 treatment watershed. At ANP total Hg concentrations in salamander larvae were significantly higher from streams in unburned watersheds in contrast with larval samples collected from streams located in watersheds burned by the 1947 Bar Harbor fire. Additionally, total Hg levels were significantly higher in salamander larvae collected at ANP in contrast with SNP. Our results suggest that watershed-scale attributes including fire history, whole-catchment (NH 4 ) 2 SO 4 additions, wetland extent, and forest cover type influence mercury bioaccumulation in salamanders inhabiting lotic environments. We also discuss the use of this species as an indicator of Hg bioaccumulation in stream ecosystems.

Maine, Virginia↗

USGS2000

The Cooperative Wildlife Research Unit and wildlife education: Historic development, future challenges

In 1932, J. N. 'Ding' Darling proposed a 3-year tripartite arrangement between the Iowa Fish and Game Commission, Iowa State University, and himself to establish the first Cooperative Wildlife Research Unit. Three years later, the Cooperative Wildlife Research Unit Program was broadened to include 9 land-grant colleges representing recognized ecoregions in the United States. In 1960, the Units were given statutory recognition by Public Law 86-686 that also included provision for establishing Cooperative Fishery Units. The Cooperative Research Unit idea has evolved to 39 Units in 2000. Today, the main cooperators of the Unit program are the land-grant university, the state fish and game or conservation agency, the U.S. Geological Survey, and the Wildlife Management Institute. The Cooperative Units mission, as stated in Public Law 86-686, remains: 'To facilitate cooperation between the Federal Government, colleges and universities, and private organizations for cooperative unit programs of research and education relating to fish and wildlife and for other purposes.' Graduate research and education continue to be the program's primary missions. In any given year >600 graduate and post-graduate students are involved. Post-graduate employment of Unit-afffiliated students is >90%. Perhaps the primary benefit to the education process is the Units' formal connection to the state cooperator and to their federal agency that might not otherwise be available to university faculty and students. Units are conduits to state and federal funding for research projects conducted by university faculty and students. The CRU program is well positioned to educate a multitalented, ethnically diverse cadre of graduate students who will be prepared not only for their first professional job but also for their career by having been instilled with a desire for life-long professional accomplishment.

Wildlife Society Bulletin↗