Diet and Digestion Rates of Slimy Sculpin, Cottus cognatus, in an Alaskan Arctic Lake

1985 ◽  
Vol 42 (3) ◽  
pp. 483-487 ◽  
Author(s):  
Anne E. Hershey ◽  
Michael E. McDonald
Keyword(s):  
Dry Weight ◽  
Age And Growth ◽  
Quadratic Model ◽  
Gut Contents ◽  
Growth Data ◽  
Passage Rate ◽  
Cottus Cognatus ◽  
Gut Passage ◽  
Slimy Sculpin ◽  
Toolik Lake

In arctic Toolik Lake, slimy sculpin (Cottus cognatus) rely on a diet of larval chironomids (Diptera: Chironomidae). Dry weight of sculpin gut contents was not correlated with fish wet weight. This finding, combined with age and growth data, suggested that sculpin may be food limited in Toolik Lake, particularly as they approach reproductive size. Since three taxonomically distinct chironomids were digested at similar rates, one chironomid species was used as a marker to measure gut passage. Gut passage rate as a function of temperature fits an inverse quadratic model slightly better than a negative exponential model. Sculpins took approximately 1 d to digest food at typical summer temperatures (8–16 °C), but approximately 2 d at a typical winter temperature (4 °C). Since winter is three times longer than summer, winter feeding by sculpins may have greater impact on chironomid density than summer feeding. If sculpin are important in the diet of other Toolik Lake fishes, they may serve as an important trophic link between benthic and pelagic production.

Site fidelity of slimy sculpin (Cottus cognatus): insights from stable carbon and nitrogen analysis

2004 ◽  
Vol 61 (9) ◽  
pp. 1717-1722 ◽  
Author(s):  
M A Gray ◽  
R A Cunjak ◽  
K R Munkittrick
Keyword(s):  
Environmental Impacts ◽  
Site Fidelity ◽  
Fish Muscle ◽  
Sentinel Species ◽  
Agricultural Activity ◽  
Local Conditions ◽  
Cottus Cognatus ◽  
Site Specific ◽  
Isotopic Signatures ◽  
Slimy Sculpin

Concerns regarding sentinel species for assessing environmental impacts include residency, abundance, and suitability for measuring responses, if effects are to be attributable to local conditions. Stable isotope analysis was used as a tool to investigate site fidelity of slimy sculpin (Cottus cognatus) to establish residency and exposure for the sculpin. We predicted that sculpin collected from sites adjacent to agricultural activity would show higher δ15N values than those collected from sites in forested areas because of isotopic enrichment by fertilizers in the former. The predominant use of chemical fertilizer applications in the region, however, resulted in no specific enrichment of 15N in sculpin collected in the agricultural region. However, there was an incremental enrichment in the fish muscle tissue of approximately 5‰ in δ13C values in a downstream direction, irrespective of surrounding land use. As a result, the dual-isotope comparison was successful at demonstrating site-specific isotopic signatures across sites for 30 km of the river system. The site-specific signatures suggest that slimy sculpin are not moving considerable distances among sites and are incorporating their isotopic signatures over a narrow spatial scale. The results support the use of the slimy sculpin as a sentinel species for investigating site-specific environmental impacts.

Food of Shorthorn Sculpin, Myoxocephalus scorpius, in the Cumberland Sound Area of Baffin Island

1974 ◽  
Vol 31 (3) ◽  
pp. 355-359 ◽  
Author(s):  
I. A. Moore ◽  
J. W. Moore
Keyword(s):  
Dry Weight ◽  
Abundant Species ◽  
The Other ◽  
Gut Contents ◽  
Baffin Island ◽  
Littorina Saxatilis ◽  
Shorthorn Sculpin ◽  
Cumberland Sound ◽  
Myoxocephalus Scorpius ◽  
Benthic Prey

One hundred shorthorn sculpins, Myoxocephalus scorpius, over 15 cm in length captured from June to October, 1972, in Cumberland Sound, Baffin Island, fed almost exclusively (90% by both numbers and dry weight) on the planktonic amphipods Pseudalibrotus glacialis and Parathemisto libellula. In contrast, 140 fish captured about the same times from nearby Pangnirtung Fjord fed heavily on the benthic gastropods Littorina saxatilis and Margarites umbilicalis (each 34% by numbers and 22% by weight) and the bivalve Modiolaria discors (16% by both). Drifting ice on Cumberland Sound probably reduced the level of illumination making the detection of benthic prey difficult and causing the sculpins in this area to feed entirely on the better illuminated, brightly colored plankton. At both localities, the most abundant species in the plankton and the epifauna were also the most frequently encountered in gut contents. On the other hand, coelenterates, planktonic gastropods, copepods, and infauna, all of which were abundant in the environment, were rarely eaten.

Irrigation Effects on Roots and Shoots of Pearl Millet (Pennisetum typhoides)

1979 ◽  
Vol 15 (2) ◽  
pp. 161-168 ◽  
Author(s):  
P. J. Gregory ◽  
G. R. Squire
Keyword(s):  
Grain Growth ◽  
Pearl Millet ◽  
Root Length ◽  
Monsoon Season ◽  
Dry Weight ◽  
Growth Data ◽  
Pennisetum Typhoides ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
Irrigation Effects

SUMMARYIrrigated and unirrigated crops of pearl millet were grown in Hyderabad, India, during the post-monsoon season of 1977. Irrigation increased both the dry weight of roots and the number of root axes, but because the additional axes were thick and unbranched the total length of roots was unaffected. However, irrigation did cause more of the root length to be in the top 20 cm of soil. Yield of the irrigated crop was higher than that of the dry crop, mainly because more tillers survived to produce grain. Grain growth of the dry crop occurred when the net growth of the crop was zero, probably because of movement of assimilate from stems to panicles. Possible strategies for improving yields are examined in the light of the growth data.

IMPACTS OF NONPOINT INPUTS FROM POTATO FARMING ON POPULATIONS OF SLIMY SCULPIN (COTTUS COGNATUS)

2005 ◽  
Vol 24 (9) ◽  
pp. 2291 ◽  
Author(s):  
Michelle A. Gray ◽  
R. Allen Curry ◽  
Kelly R. Munkittrick
Keyword(s):  
Cottus Cognatus ◽  
Slimy Sculpin

Fecundity of the Slimy Sculpin, Cottus cognatus, in Lake Michigan

Copeia ◽  
1976 ◽  
Vol 1976 (4) ◽  
pp. 802 ◽  
Author(s):  
Jeffrey W. Foltz
Keyword(s):  
Lake Michigan ◽  
Cottus Cognatus ◽  
Slimy Sculpin

scholarly journals Coconut Coir and Peat Biocontainers Influence Plant Growth Retardant Drench Efficacy

2018 ◽  
Vol 28 (3) ◽  
pp. 370-377 ◽  
Author(s):  
Nicholas J. Flax ◽  
Christopher J. Currey ◽  
James A. Schrader ◽  
David Grewell ◽  
William R. Graves
Keyword(s):  
Plant Growth ◽  
Substrate Surface ◽  
Growth Index ◽  
Dry Weight ◽  
Growth Retardant ◽  
Rice Hull ◽  
Growth Data ◽  
Greenhouse Production ◽  
Uncoated Paper ◽  
Coconut Coir

We evaluated the effects of seven types of 4.5-inch top-diameter biocontainers and five rates of paclobutrazol drench on the growth and development of angelonia (Angelonia angustifolia ‘Serena White’) and petunia (Petunia ×hybrida ‘Wave® Purple Improved Prostrate’) during greenhouse production. The container types included were biopolyurethane-coated paper fiber; uncoated paper fiber; rice hull; coconut coir; peat; two types of bioplastic container, one made from 90% polylactic acid (PLA) and 10% lignin [PLA-lignin (90/10 by weight)] and another made from 60% PLA and 40% soy polymer with adipic anhydride {SP.A [PLA-SP.A]; (60/40 by weight)}; and a petroleum-based plastic control. All containers were filled with 590 mL of substrate composed of (by vol) 75% canadian sphagnum moss and 25% perlite. Ten days after transplanting seedlings, 2-fl oz aliquots of deionized water containing 0, 1, 2.5, 5, 10, or 20 mg·L−1 paclobutrazol were applied to the substrate surface as drenches. The date of anthesis was recorded for each plant, and growth data were collected 6 weeks after transplant. Shoots were harvested and dried and shoot dry weight (SDW) was recorded. Height (angelonia only) and diameter of angelonia and petunia and time to flower were calculated. Container type and paclobutrazol concentration interacted to affect size and SDW of angelonia and petunia. Growth index of angelonia treated with 0 mg·L−1 paclobutrazol and grown in coir and peat containers was 19% to 29% and 29% to 38% smaller than that of plants in other container types, respectively. Diameter of untreated petunia grown in peat containers was similar to that of those grown in coir and uncoated paper fiber containers, but was smaller (10.9 to 13.5 cm) than that of plants grown in other container types. As paclobutrazol concentrations increased from 0 to 20 mg·L−1 treatments, SDWs of petunia grown in coir containers were suppressed by 23%, whereas plants grown in rice hull containers were up to 45% less. Our results indicate that growth suppression of angelonia and petunia grown in biocontainers using paclobutrazol drenches varies by the type of biocontainer. Producers should reduce paclobutrazol drench concentrations to produce plants of appropriate size if substituting coir or peat biocontainers for traditional petroleum plastics, whereas no adjustment in plant growth retardant (PGR) drench concentrations is required for plants produced in the other biocontainer types we evaluated.

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