Response of the crayfish Cambarus bartonii bartonii to acid exposure in southern Appalachian streams

1991 ◽  
Vol 69 (6) ◽  
pp. 1585-1591 ◽  
Author(s):  
Robert J. Distefano ◽  
Richard J. Neves ◽  
Louis A. Helfrich ◽  
Mark C. Lewis
Keyword(s):  
Sublethal Effects ◽  
Acid Tolerance ◽  
Reproductive Activity ◽  
Acid Exposure ◽  
Initial Increase ◽  
Molt Cycle ◽  
Southern Appalachian ◽  
Exposure Levels ◽  
Normal Acidity ◽  
Appalachian Streams

Intermolt adult and juvenile Cambarus bartonii bartonii (Fabricius) from southern Appalachian Mountains streams tolerated considerable acidity when acutely exposed to greatly reduced pH levels in laboratory bioassays. Tolerance increased with increasing size or age of crayfish. Ninety-six-hour exposures yielded LC50 values of pH 2.43, 2.56, and 2.85 for adults, advanced juveniles, and early juveniles, respectively. Lowering the water temperature increased the acid tolerance and survival time of intermolt adults during severe acidification (temperatures ranged from 20.2 to 13.3 °C). Acid exposure of intermolt adults in soft water up to 96 h caused a linear decrease in hemolymph [Na]. Hemolymph [Ca] increased through 48 h and then returned to near pre-exposure levels. An initial increase in [K] was followed by a decrease to slightly below pre-exposure levels. Hemolymph [Mg] remained unchanged. No Ca was lost from carapaces. These observations indicate that occasional episodes of higher than normal acidity in southern Appalachian streams are not necessarily a threat to intermolt adult and juvenile C. b. bartonii. Nevertheless, gradually increasing acidity and loss of watershed buffering capacity could produce sublethal effects such as altered reproductive activity, or changes in early life history stages and more sensitive molt cycle stages, that could damage these populations.

Strategies for coexistence in three species of net-spinning caddisflies (Trichoptera) in second-order southern Appalachian streams

1977 ◽  
Vol 55 (11) ◽  
pp. 1829-1840 ◽  
Author(s):  
Diane Malas ◽  
J. Bruce Wallace
Keyword(s):  
Particle Size ◽  
Vascular Plant ◽  
Distribution Patterns ◽  
Gut Contents ◽  
Dietary Composition ◽  
Particle Sizes ◽  
Southern Appalachian ◽  
Fine Particulate ◽  
Animal Material ◽  
Appalachian Streams

Three species of net-spinning caddisflies, Parapsyche cardis, Diplectrona modesta, and Dolophilodes distinctus were studied. Larvae of Dolophilodes are found at the lowest current velocities followed by Diplectrona, then Parapsyche, which prefer the higher velocities. Parapsyche larvae are most abundant on upper surfaces of stones while Diplectrona and Dolophilodes are found primarily on undersides of stones. These distribution patterns are probably related to capture net mesh dimensions which differ greatly for the three species, Parapsyche having the largest and Dolophilodes the smallest meshes. Significant correlations existed for mean foregut particle size and capture net mesh opening size between instars of all species within seasons, between instars of all species throughout the year, and between instars within species throughout the year. These correlations support the contention that particle size selection is an important aspect of feeding differences between species. There are large differences between mesh opening sizes of last-instar Dolophilodes and first- and second-instar Diplectrona larvae. However, based on mean particle size measurements of foregut contents, there is no corresponding gap in the spectrum of particle sizes used for food. Dietary composition also varied between species. Parapsyche consumed primarily animal material. Fine particulate detritus composed over 95% of Dolophilodes gut contents and Diplectrona consumed mostly vascular plant and detritus fragments in late instars and fine particulate detritus in early instars.

Comparative Analysis of Acid Resistance between Susceptible and Multi-Antimicrobial-Resistant Salmonella Strains Cultured under Stationary-Phase Acid Tolerance–Inducing and Noninducing Conditions

2003 ◽  
Vol 66 (5) ◽  
pp. 732-740 ◽  
Author(s):  
R. T. BACON ◽  
J. N. SOFOS ◽  
P. A. KENDALL ◽  
K. E. BELK ◽  
G. C. SMITH
Keyword(s):  
Stationary Phase ◽  
Antimicrobial Agents ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Acid Resistance ◽  
Low Ph ◽  
Acid Exposure ◽  
Acid Adaptation ◽  
Acid Shock ◽  
Resistant Strains

This study compared acid resistance levels among five antimicrobial-susceptible strains of Salmonella and five strains that were simultaneously resistant to a minimum of six antimicrobial agents. The induction of a stationary-phase acid tolerance response (ATR) was attempted by both transient low-pH acid shock and acid adaptation. For acid shock induction, strains were grown for 18 h in minimal E medium containing 0.4% glucose (EG medium) and exposed to sublethal acid stress (pH 4.3) for 2 h, and subsequently, both shocked and nonshocked cultures were acid challenged (pH 3.0) for 4 h. Acid adaptation was achieved by growing strains for 18 h in tryptic soy broth containing 1.0% glucose (TSB+G), while nonadapted cultures were grown for 18 h in glucose-free tryptic soy broth (TSB−G). Acid-adapted and nonadapted inocula were acid challenged (pH 2.3) for 4 h. Initial (0 h) mean populations of nonchallenged Salmonella were 8.5 to 8.7, 8.4 to 8.8, and 8.2 to 8.3 log CFU/ml for strains grown in EG medium, TSB−G, and TSB+G, respectively. After 4 h of acid challenge, mean populations were 3.0 to 4.8 and 2.5 to 3.7 log CFU/ml for previously acid-shocked susceptible and resistant strains, respectively, while corresponding counts for nonshocked strains were 4.3 to 5.5 log CFU/ml and 3.9 to 4.9 log CFU/ml. Following 4 h of acid exposure, acid-adapted cultures of susceptible and resistant strains had mean populations of 6.1 to 6.4 log CFU/ml and 6.4 to 6.6 log CFU/ml, respectively, while corresponding counts for nonadapted cultures were 1.9 to 2.1 log CFU/ml and 1.8 to 2.0 log CFU/ml, respectively. A low-pH–inducible ATR was not achieved through transient acid shock, while an ATR was evident following acid adaptation, as adapted populations were 4.2 to 4.8 log units larger than nonadapted populations following acid exposure. Although some strain-dependent variations in acid resistance were observed, results from this study suggest no association between susceptibility to antimicrobial agents and the ability of the Salmonella strains evaluated to survive low-pH stress.

Effects of forest disturbance on leaf breakdown in southern Appalachian streams

1991 ◽  
Vol 24 (3) ◽  
pp. 1687-1690 ◽  
Author(s):  
E. F. Benfield ◽  
J. R. Webster ◽  
S. W. Golladay ◽  
G. T. Peters ◽  
B. M. Stout
Keyword(s):  
Forest Disturbance ◽  
Leaf Breakdown ◽  
Southern Appalachian ◽  
Appalachian Streams

scholarly journals Impacts of Petroleum, Petroleum Components, and Dispersants on Organisms and Populations

Oceanography ◽  
2021 ◽  
Vol 34 (1) ◽  
pp. 136-151
Author(s):  
Steven Murawski ◽  
◽  
Martin Grosell ◽  
Cynthia Smith ◽  
Tracey Sutton ◽  
...  
Keyword(s):  
Sublethal Effects ◽  
Future Research ◽  
Molecular Tools ◽  
Short Term ◽  
Testing Procedures ◽  
Laboratory Results ◽  
Polycyclic Aromatic ◽  
Chemical Studies ◽  
Exposure Levels

Following the Deepwater Horizon blowout, oil, degraded oil, oil mixed with dispersants, and management responses to the spill affected a variety of Gulf of Mexico organisms. This review provides examples of various documented impacts, common patterns, and trends across organisms and/or their environments, and discusses future implications as well as directions for future research. Organism effects are generally characterized as lethal and sublethal. Sublethal can be short term, long term, or permanent and multigenerational. We present individual examples of effects on behavioral response, olfaction, vision, cardiac function, and gene shift, based on research done in laboratories, mesocosm settings, and the field. Future research should emphasize collection and analysis of routine toxicological baselines and examine how and if molecular impacts cascade up to populations. This research will require development of rapid molecular tools and testing procedures to determine exposure compared to field-relevant exposure levels and to be able to extrapolate laboratory results to the field, especially given the mosaic of differing contaminant concentrations (below, at, or exceeding critical concentrations that result in lethal or sublethal effects) occurring in the environment. Recent chemical studies have identified a detectable suite of polycyclic aromatic hydrocarbon metabolites for which there are no toxicity data; further research is needed to determine their impacts on food webs.

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