Glycerol and water balance in a near-isosmotic teleost, winter-acclimatized rainbow smelt

1993 ◽  
Vol 71 (9) ◽  
pp. 1849-1854 ◽  
Author(s):  
James A. Raymond
Keyword(s):  
Water Balance ◽  
Freezing Point ◽  
Urine Flow ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Water Losses ◽  
Drinking Rate ◽  
Osmotic Water ◽  
High Concentrations ◽  
Reduced Drinking

Rainbow smelt, Osmerus mordax, have previously been shown to produce high concentrations of glycerol in winter to avoid freezing, becoming almost isosmotic in a marine environment when temperatures reach the freezing point of seawater. Here it is shown that osmotic water losses, as shown by drinking rate, decrease dramatically in winter as a result of the increased osmolality. Urine flow also appears to decrease in winter in response to reduced drinking. Glycerol is lost through the skin and gills, and probably through intestinal discharge, at total rates ranging from 3.5 to 9.5 mg∙100 g−1∙h−1. Combined permeabilities to glycerol of the gills and skin in the head were in the range 0.9–2.6 × 10−7 cm∙s−1. Glycerol concentrations, efflux, and permeability of the gills were comparable to those for urea in marine elasmobranchs. However, mechanisms for conserving the two osmolytes may differ.

Glycerol-3-phosphatase and not lipid recycling is the primary pathway in the accumulation of high concentrations of glycerol in rainbow smelt (Osmerus mordax)

2013 ◽  
Vol 304 (4) ◽  
pp. R304-R312 ◽  
Author(s):  
Delphine Ditlecadet ◽  
William R. Driedzic
Keyword(s):  
Lipid Metabolism ◽  
Carbon Cycling ◽  
Animal Species ◽  
Strong Support ◽  
Small Fish ◽  
Osmerus Mordax ◽  
Glycerol Production ◽  
Rainbow Smelt ◽  
Hepatic Cells ◽  
High Concentrations

Rainbow smelt is a small fish that accumulates glycerol in winter as a cryoprotectant when the animal is in seawater. Glycerol is synthesized in liver from different substrates that all lead to the formation of glycerol-3-phosphate (G3P). This study assesses whether glycerol is produced by a direct dephosphorylation of G3P by a phosphatase (G3Pase) or by a cycling through the glycerolipid pool followed by lipolysis. Foremost, concentrations of on-board glycerolipids and activity of G3Pase and of enzymes involved in lipid metabolism were measured in smelt liver over the glycerol cycle. Concentrations of on-board glycerolipids did not change over the cycle and were too low to significantly contribute directly to glycerol production but activities of enzymes involved in both potential pathways were up-regulated at the onset of glycerol accumulation. A second experiment conducted with isolated hepatic cells producing glycerol showed 1) that on-board glycerolipids were not sufficient to produce the glycerol released even though phospholipids could account for up to 17% of it, 2) that carbon cycling through the glycerolipid pool was not involved as glycerol was produced at similar rates following inhibition of this pathway, and 3) that G3Pase activity measured was sufficient to allow the synthesis of glycerol at the rate observed. These results are the first to clearly support G3Pase as the metabolic step leading to glycerol production in rainbow smelt and the first to provide strong support for a G3Pase in any animal species.

Sodium, Chloride and Water Balance of the Intertidal Teleost, Xiphister Atropurpureus

1967 ◽  
Vol 47 (3) ◽  
pp. 519-524
Author(s):  
DAVID H. EVANS
Keyword(s):  
Sodium Chloride ◽  
Water Balance ◽  
Sea Water ◽  
Urine Flow ◽  
Drinking Rate ◽  
Euryhaline Teleost ◽  
Xiphister Atropurpureus ◽  
Low Rate

1. The rate of loss of sodium, chloride and water via the urine and the rate of intake of sodium, chloride and water by ingestion of the medium was determined for the euryhaline teleost, Xiphister atropurpureus. 2. The urinary losses of sodium and chloride were approximately 0.5 mM/kg. fish/day in both 100 % sea water (480 mM-Na/kg.) and 10% sea water. The ingestion of sodium and chloride by drinking the medium amounted to approximately 4 mM/kg. fish/day in 100% sea water and approximately 0.1 mM/kg. fish/day in 10% sea water. 3. The low rate of urine flow in 10 % sea water and the low drinking rate in 100 % sea water indicate a relative impermeability to water in both salinities.

Hypoxia modifies planktivore–zooplankton interactions in Lake Erie

2012 ◽  
Vol 69 (12) ◽  
pp. 2018-2028 ◽  
Author(s):  
Steven A. Pothoven ◽  
Henry A. Vanderploeg ◽  
Tomas O. Höök ◽  
Stuart A. Ludsin
Keyword(s):  
Lake Erie ◽  
Osmerus Mordax ◽  
Large Prey ◽  
Bythotrephes Longimanus ◽  
Rainbow Smelt ◽  
Leptodora Kindtii ◽  
Vertical Distributions ◽  
Consumption Rates ◽  
High Concentrations ◽  
Zooplankton Production

We evaluated vertical distributions of fish and zooplankton, planktivore consumption, and prey production in Lake Erie during 2005 to determine how hypolimnetic hypoxia alters fish (i.e., rainbow smelt (Osmerus mordax) and emerald shiners (Notropis atherinoides)) and invertebrate planktivore (i.e., Bythotrephes longimanus and Leptodora kindtii) relationships with their mesozooplankton prey. Hypoxia concentrated 45%–76% of fish into a narrow (<2 m) metalimnetic layer, but only 3%–13% of zooplankton production was in this layer. The epilimnion may have served to some degree as a refuge for mesozooplankton because high temperatures may have excluded rainbow smelt. High concentrations of fish above the hypolimnion likely resulted in increased competition for large prey (i.e., predatory claodcerans). Although hypoxia did not result in overall high predation demands by planktivores relative to total zooplankton production, planktivore consumption rates within the metalimnion exceeded zooplankton production in that layer.

scholarly journals Intestinal Na+ and Cl- levels control drinking behavior in the seawater-adapted eel Anguilla japonica

1996 ◽  
Vol 199 (3) ◽  
pp. 711-716 ◽  
Author(s):  
M Ando ◽  
K Nagashima
Keyword(s):  
Sea Water ◽  
Direct Action ◽  
Choline Chloride ◽  
Drinking Behavior ◽  
Anguilla Japonica ◽  
Urine Flow ◽  
Perfusion Medium ◽  
Drinking Rate ◽  
Gastrointestinal Fluid ◽  
High Concentrations

To analyze drinking mechanisms in seawater teleosts, seawater-adapted eels were used as a model system. When the intestine of the eel was perfused with iso-osmotic mannitol, the eels drank sea water. However, when the perfusion medium was switched to iso-osmotic NaCl, seawater drinking was depressed. This depression was observed even after blocking NaCl absorption across the intestine by replacement of the perfusate with choline chloride or by treatment with furosemide, an inhibitor of NaCl and water absorption across the eel intestine. Furthermore, depression of drinking rate preceded an increase in urine flow by over 1 h. These results indicate that this depression is not due to a recovery of blood volume and suggest that intestinal Cl- itself inhibits drinking. Direct action of luminal Cl- on drinking behavior was further supported by the observation that perfusion with iso-osmotic NMDG-HCl, Tris-HCl, choline chloride and RbCl all inhibited seawater drinking. When NaCl in the perfusion medium was replaced with sodium acetate, sodium butyrate, sodium methylsulfate or NaSCN, the drinking rate was enhanced threefold, suggesting that Na+ itself stimulates drinking in the absence of Cl-. In the present study, concentrations of Na+ and Cl- in the swallowed fluid were also measured simultaneously. As the drinking rate was enhanced, the Na+ and Cl- concentrations in the gastrointestinal fluid were increased. On the basis of these results, it seems possible that high concentrations of Cl- in the intestine reduce the drinking rate, thus lowering esophageal Cl- concentration due to desalination of the ingested sea water. When Cl- concentration in the intestine falls below a certain level, Na+ will stimulate seawater drinking again.

scholarly journals Adaptations to a Terrestrial Existence by the Robber Crab Birgus Latro: VI. The Role of the Excretory System in Fluid Balance

1990 ◽  
Vol 152 (1) ◽  
pp. 505-519 ◽  
Author(s):  
PETER GREENAWAY ◽  
H. H. TAYLOR ◽  
S. MORRIS
Keyword(s):  
Drinking Water ◽  
Fresh Water ◽  
Fluid Balance ◽  
Filtration Rate ◽  
Sea Water ◽  
Urine Flow ◽  
Water Losses ◽  
Drinking Rate ◽  
The Difference

Primary urine is formed by filtration in the antennal organ of Birgus latro L. Urine isosmotic with the haemolymph is released into the anterior branchial chambers where substantial reabsorption of water and ions may occur. Some of the branchial fluid is ingested and the remainder (final excretory fluid, P) is released. Crabs supplied with fresh water have a low drinking rate (1.82 ml 100 g−1 day−1). Primary urine is partially reabsorbed (27%) in the antennal organ and urine flow (4.48 ml 100 g−1 day−1) is significantly lower than filtration rate (5.77 ml 100 g−1 day−1). The volume of P released is small in crabs drinking fresh water (0.45 ml 100 g−1 day−1) and the fluid is dilute (≈25 mmol l−1 NaCl). The difference between P flow and drinking rate (1.37 ml 100 g−1 day−1) represents evaporative and faecal water losses. Provision of saline drinking water (300, 600 or 1000 mosmol kg−1 sea water) doubles rates of drinking, filtration and urine flow and increases P flow fourfold. Evaporative/faecal water loss remains constant. Reabsorption of salts from the P rapidly decreases when saline media are provided for drinking.

Fish community change in Lake Superior, 1970–2000

2003 ◽  
Vol 60 (12) ◽  
pp. 1552-1574 ◽  
Author(s):  
Charles R Bronte ◽  
Mark P Ebener ◽  
Donald R Schreiner ◽  
David S DeVault ◽  
Michael M Petzold ◽  
...  
Keyword(s):  
Great Lakes ◽  
Native Species ◽  
Fish Community ◽  
Lake Trout ◽  
Community Change ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Additional Species ◽  
Community Agencies ◽  
Natural Reproduction

Changes in Lake Superior's fish community are reviewed from 1970 to 2000. Lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) stocks have increased substantially and may be approaching ancestral states. Lake herring (Coregonus artedi) have also recovered, but under sporadic recruitment. Contaminant levels have declined and are in equilibrium with inputs, but toxaphene levels are higher than in all other Great Lakes. Sea lamprey (Petromyzon marinus) control, harvest limits, and stocking fostered recoveries of lake trout and allowed establishment of small nonnative salmonine populations. Natural reproduction supports most salmonine populations, therefore further stocking is not required. Nonnative salmonines will likely remain minor components of the fish community. Forage biomass has shifted from exotic rainbow smelt (Osmerus mordax) to native species, and high predation may prevent their recovery. Introductions of exotics have increased and threaten the recovering fish community. Agencies have little influence on the abundance of forage fish or the major predator, siscowet lake trout, and must now focus on habitat protection and enhancement in nearshore areas and prevent additional species introductions to further restoration. Persistence of Lake Superior's native deepwater species is in contrast to other Great Lakes where restoration will be difficult in the absence of these ecologically important fishes.

Planktivory by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario

1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman
Keyword(s):  
Laboratory Experiments ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Field Observations ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Consumption Rates ◽  
South Shore ◽  
Young Of The Year ◽  
Veliger Larvae

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

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