Indirect effects of lake acidification on Chaoborus population dynamics: the role of food limitation and predation

1997 ◽  
Vol 54 (3) ◽  
pp. 637-646 ◽  
Author(s):  
J M Fischer ◽  
T M Frost
Keyword(s):  
Food Limitation ◽  
Fish Predation ◽  
Invertebrate Predation ◽  
Little Rock ◽  
Chaoborus Punctipennis ◽  
Consistent Manner ◽  
Experimental Acidification ◽  
Ambloplites Rupestris ◽  
Mesocyclops Edax

A twofold increase in Chaoborus punctipennis abundance following experimental acidification of one basin of Little Rock Lake, Wisconsin, provided an opportunity to examine the hypotheses that C. punctipennis dynamics were regulated by (i) food resources for instars I and II, (ii) fish predation on instars III and IV, and (iii) invertebrate predation on instars I and II. Neither food limitation nor fish predation appeared to be important constraints on C. punctipennis abundance. Although rotifer biomass increased significantly during the acidification, C. punctipennis did not respond in a consistent manner to variation in food availability. Bioenergetics estimates of C. punctipennis consumption by rock bass (Ambloplites rupestris), the most acid-sensitive fish species, were small compared with C. punctipennis production. In contrast, invertebrate predation appeared to be an important constraint on C. punctipennis abundance. Chaoborus punctipennis abundance increased dramatically when abundance of the predator Mesocyclops edax declined to near zero. Comparison of M. edax predation rates and first instar production suggested that M. edax could exert strong predation pressure on C. punctipennis Thus, invertebrate predation may create a juvenile bottleneck for populations of small-bodied Chaoborus species in moderately productive acidified lakes.

Experimental Acidification of Little Rock Lake, Wisconsin: Chemical and Biological Changes over the pH Range 6.1 to 4.7

1993 ◽  
Vol 50 (5) ◽  
pp. 1101-1121 ◽  
Author(s):  
P. L. Brezonik ◽  
J. G. Eaton ◽  
T. M. Frost ◽  
P. J. Garrison ◽  
T. K. Kratz ◽  
...  
Keyword(s):  
Micropterus Salmoides ◽  
Little Rock ◽  
Pomoxis Nigromaculatus ◽  
Food Web Interactions ◽  
Biological Responses ◽  
Seepage Lake ◽  
Experimental Acidification ◽  
Ph Range ◽  
Ambloplites Rupestris ◽  
Oak Leaves

The two basins of this seepage lake were separated by a vinyl curtain in August 1984 after a year of background studies, and acidification of one basin with H2SO4 began at ice-out in 1985. Chemical and biological responses measured during successive 2-yr periods at pH ~5.6, 5.1, and 4.7 verified some but not all impacts predicted at the outset. Changes in major, minor, and trace ions generally agreed with predictions. Internal alkalinity generation (IAG) increased at lower pH, and sulfate reduction eliminated ~50% of added H2SO4. Sediment cation exchange was important in IAG and acidified surface sediments, possibly diminishing the lake's ability to counteract further H+ inputs. Mass loss of oak leaves was reduced at pH 5.1 (birch leaves at pH 4.7). Population parameters were more sensitive than community measures for plankton. Species composition changed at each pH, especially at pH 4.7. Many changes in zoopiankton and benthos were indirect responses to an algal mat that developed at lower pH or to food web interactions; these were not predicted accurately. Sensitivity of major fishes to lower pH was Ambloplites rupestris > Micropterus salmoides > Pomoxis nigromaculatus > Perca flavescens. Fish production was reduced at pH's above those resulting in population decreases.

Chaoborus populations: response to food web manipulation and potential effects on zooplankton communities

1987 ◽  
Vol 65 (12) ◽  
pp. 2846-2852 ◽  
Author(s):  
Monica M. Elser ◽  
Carl N. von Ende ◽  
Patricia Sorrano ◽  
Stephen R. Carpenter
Keyword(s):  
Food Web ◽  
Food Limitation ◽  
Major Change ◽  
Fish Predation ◽  
Chaoborus Flavicans ◽  
Reference Lake ◽  
Chaoborus Punctipennis ◽  
Consumption Rates ◽  
Zooplankton Communities ◽  
Major Reduction

Chaoborus populations were studied in two lakes in which fish predation was experimentally reduced, and in a reference lake. In Tuesday Lake, major reduction of fish predation led to substantial increases in density of Chaoborus punctipennis. Analysis of crop contents and estimates of consumption rates suggested that C. punctipennis caused declines of rotifer and copepod populations following the manipulations. In Peter Lake, lesser changes in fish predation caused no major change in density of Chaoborus flavicans, perhaps because food limitation compensated for effects of reduced predation. In both Peter Lake and the reference lake, Paul Lake, C. flavicans preyed heavily and selectively on Daphnia less than about 1.4 mm in total length. Bioenergetic calculations indicated that up to 46% of the daphnids were consumed daily. At some times of the year, certain zooplankton populations (especially noncolonial rotifers, small copepods, and small cladocerans) were strongly influenced by Chaoborus predation.

scholarly journals Global monopole metric in 2 + 1 dimensions

2019 ◽  
Vol 16 (01) ◽  
pp. 1950006
Author(s):  
S. Habib Mazharimousavi ◽  
M. Halilsoy
Keyword(s):  
Exact Solution ◽  
Cosmological Constant ◽  
Electric Charge ◽  
Radial Distance ◽  
Series Solutions ◽  
Global Monopole ◽  
Negative Cosmological Constant ◽  
Consistent Manner ◽  
Positive Integers

In order to obtain the geometry of a global monopole without cosmological constant and electric charge in [Formula: see text] dimensions, we make use of the broken [Formula: see text] symmetry. In the absence of an exact solution, we determine the series solutions for both the metric and monopole functions in a consistent manner that satisfies all equations in appropriate powers. The new expansion elements are of the form [Formula: see text] for the radial distance [Formula: see text] and positive integers [Formula: see text] and [Formula: see text] constrained by [Formula: see text]. To the lowest order of expansion, we find that in analogy with the negative cosmological constant the geometry of the global monopole acts repulsively, i.e. in the absence of a cosmological constant the global monopole plays at large distances the role of a negative cosmological constant.

Racial and Moral Crisis: The Role of Little Rock Ministers

1959 ◽  
Vol 64 (5) ◽  
pp. 509-516 ◽  
Author(s):  
Ernest Q. Campbell ◽  
Thomas F. Pettigrew
Keyword(s):  
Little Rock ◽  
Moral Crisis

Effects of fish predation in erosional and depositional habitats in a temperate stream

2000 ◽  
Vol 57 (7) ◽  
pp. 1369-1379 ◽  
Author(s):  
Jordan Rosenfeld
Keyword(s):  
Coho Salmon ◽  
Resource Limitation ◽  
Fish Predation ◽  
Benthic Invertebrate ◽  
Invertebrate Community ◽  
Ceramic Tiles ◽  
Organic Detritus ◽  
Predation Effects ◽  
Temperate Stream

Combined effects of predation by benthic and drift-foraging fish (prickly sculpin (Cottus asper) and coho salmon (Onchorhynchus kisutch) parr) on benthic invertebrate community and trophic structure were evaluated in Mayfly Creek, a previously fishless stream in the Coast Range Mountains of British Columbia. The role of microhabitat (substrate) in mediating predation effects was assessed by comparing invertebrate community structure on unglazed ceramic tiles and gravel baskets nested within enclosures. The role of macrohabitat was evaluated by placing enclosures in pool and riffle habitats. Effects of fish predation were most pronounced on tile substrate and in riffle habitat and least pronounced on gravel substrate in pool habitat. The presence of fish caused a decrease in abundance of larger-bodied herbivores (primarily the mayflies Ameletus and Baetis) and had positive indirect effects on algae and smaller invertebrates (primarily Orthocladiinae chironomids and nemourid stoneflies), probably through competitive release. In contrast with herbivores, detritivorous invertebrates were less influenced by fish predation and more highly correlated with the abundance of organic detritus. The distribution and abundance of detritivores in Mayfly Creek appear to be primarily influenced by bottom-up forces (implying resource limitation), while grazers in algal-based food chains are more strongly influenced by top-down effects (fish predation).

Experimental acidification of Little Rock Lake (Wisconsin): Fish research approach and early responses

1989 ◽  
Vol 18 (1-2) ◽  
pp. 167-174 ◽  
Author(s):  
William A. Swenson ◽  
J. Howard McCormick ◽  
Timothy D. Simonson ◽  
Kathleen M. Jensen ◽  
John G. Eaton
Keyword(s):  
Research Approach ◽  
Little Rock ◽  
Little Rock Lake ◽  
Experimental Acidification ◽  
Rock Lake

Enhancing and supporting the role of academic tutors in developing undergraduate writing skills: Reflections on the experiences of a social work education programme

2012 ◽  
Vol 5 (2) ◽  
pp. 27-48 ◽  
Author(s):  
Nathan Hughes ◽  
Sue Wainwright ◽  
Caroline Cresswell
Keyword(s):  
Academic Writing ◽  
Academic Support ◽  
Writing Skills ◽  
Education Programme ◽  
Independent Study ◽  
Learning Needs ◽  
Consistent Manner ◽  
Effective Use ◽  
Work Education

Whilst approaches to the development of undergraduate academic writing skills vary between disciplines and institutions, academic tutors are consistently presented as playing an important role. One aspect of this role is supporting students to engage effectively with feedback in order to develop consciousness and competence regarding academic writing. This article reports on the use of a form, which was designed to encourage students to use feedback in a structured and consistent manner and to support subsequent tutor-tutee dialogue. Students and tutors who used the form suggest it encouraged students to reflect on their learning needs and identify priority issues for discussion with the tutor. However, barriers to its effective use remain. In particular, there was resistance amongst students to accessing academic support, due to anxieties that staff would look negatively upon those who seek help. Students expressed concern that tutors would perceive those seeking support as failing to cope with the demands of independent study, a set of skills they perceive that they were required to have on arrival at university, rather than to acquire during the course of their studies with the help and guidance of their academic tutor.

Experimental acidification of Little Rock Lake, Wisconsin: The first four years of chemical and biological recovery

1995 ◽  
Vol 85 (3) ◽  
pp. 1713-1719 ◽  
Author(s):  
C. J. Sampson ◽  
P. L. Brezonk ◽  
T. M. Frost ◽  
K. E. Webster ◽  
T. D. Simonson
Keyword(s):  
Little Rock ◽  
Biological Recovery ◽  
Little Rock Lake ◽  
Experimental Acidification ◽  
Rock Lake
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