Patterns Of Osmoregulation Research Articles

Ontogeny of osmoregulation, physiological plasticity and larval export strategy in the grapsid crab Chasmagnathus granulata (Crustacea, Decapoda)

The grapsid crab Chasmagnathus granulata populates brackish-water lagoons and other estuarine environments. In its reproduction, this species follows a strategy of larval export, i.e. its larvae live under different salinity conditions from the juveniles and adults. In the present experi- mental investigation, ontogenetic changes in the capability for osmoregulation were studied in all 4 zoeal stages, the megalopa, the juvenile crab instars I, II and IV, and adults (all reared in seawater, 32‰). Moreover, we studied effects of embryonic and larval acclimation on osmoregulation. The zoea I larvae were slight hyper-regulators at low salinities (10 to 17‰) and hyper-osmoconformers at higher salinities. Stages II to IV zoeae were generally hyper-osmoconformers. At metamorphosis to the megalopa, the type of osmoregulation changed to hyper-hypo-regulation. The osmoregulatory capacities under both hypo- and hypersaline conditions increased strongly in the crab I and through- out later juvenile development. These patterns in osmoregulation match the ontogenetic changes that typically occur in the ecology of C. granulata: the zoea I hatches in brackish estuarine waters, where the juveniles and adults live, before it is exported to coastal marine zones. This initial larval stage is euryhaline and capable of hyper-osmoregulation at low salinities. The same capabilities were observed in the megalopa, which re-invades the brackish adult environment. This stage is known to settle in semiterrestrial habitats near the adult burrows, where both brackish and hypersaline condi- tions are likely to occur; this coincides with the first ontogenetic appearance of the hyper-hypo- osmoregulation pattern. The zoeal stages II, III and IV, in contrast, develop in the adjacent sea, where the salinity is higher and more stable. Correspondingly, these intermediate larval stages were found to be stenohaline osmoconformers. Preceding exposure of the eggs and larvae to a reduced salinity (20‰) enhanced the hyper-osmoregulatory capacity at low salinities (5 to 10‰) in all zoeal stages. This indicates an effect of non-genetic acclimation and, hence, phenotypic plasticity. This trait should have an adaptive value, as it increases the chance of larval survival, at least in the initial larval stage, which is in the field exposed to highly variable, mostly reduced salinities.

432 Irrigation Frequency Affects Growth and Water Use Efficiency of Two Xeriphytic Landscape Plants

Growth and water use efficiency (WUE) of two Southwest landscape plants under various regimes of irrigation frequency was studied in a greenhouse experiment. Red bird of paradise (Caesalpinia pulcherrima L.) and blue palo verde (Cercidium floridum Benth. ex A. Gray) were grown at three levels of irrigation frequency intended to mimic a range of watering practices determined via survey data from the Phoenix, Ariz., metropolitan area. During two irrigation cycles, measurement of mid-day water and osmotic potentials, lysimetric whole-plant transpiration (T), and mid-day shoot gas exchange was made. Irrigation frequency treatments affected Cercidium more than Caesalpinia. Frequent irrigations increased Cercidium shoot length and dry weight. For both species, infrequently irrigated plants showed patterns of osmoregulation in response to drying soil. Transpiration (T) was consistently highest for infrequently irrigated plants. WUE was affected by treatment for Cercidium, but not Caesalpinia. Gas exchange was unrelated to plant growth or T. Instantaneous transpiration efficiency (ITE) was negatively correlated to the ratio of intracellular CO2 to ambient (CICA) in all treatments, suggesting that under well-watered conditions, WUE might be reduced by negative feedback effects of high internal CICA ratios.

Osmoregulation by Adélie Penguin Chicks on the Antarctic Peninsula

-Physiologists have long contended that consumption of a diet of marine invertebrates imposes a high salt load on animals. I measured water and salt contents in the food, excreta, and body fluids of Ad6lie Penguin (Pygoscelis adeliae) chicks to determine patterns of osmoregulation in a bird that eats almost exclusively marine invertebrates. Adelie Penguins eat krill (Euphausia spp.) and feed the same to their chicks by regurgitation. Adelie chicks sometimes receive food that is significantly saltier than their body fluids, but on average the food has salt concentrations similar to those in their plasma. Adelie chicks excrete excess solutes via the salt glands, which are fully functional at hatching, and via the kidneys, which produce urine that is more concentrated relative to urine of other bird species. Larger chicks receive food that is drier than that eaten by smaller chicks, and larger chicks may compensate by excreting more of a given salt load via the salt glands, thus conserving water. Regurgitated food has significantly less Na+ than Cl-, but the salt glands secrete equal amounts of these two ions. Consequently, in larger chicks Na+ may be shunted from the urine to be excreted via the salt glands. The loss of this cation in the urine is compensated for by addition of NH4+. Received 26 July 1996, accepted 1 February 1997. ADPLIE PENGUINS (Pygoscelis adeliae) live in an osmotically challenging marine environment. Adelie Penguins have little or no access to fresh water, and up to 99% of their diet is marine invertebrates, usually krill (mostly Euphausia superba; Volkman et al. 1980). Adelie chicks potentially face the same osmotic challenges as the adults, because the only food they receive is that regurgitated by their parents. Unless adults modify the composition of krill fed to chicks, then the chicks' osmoregulatory physiology must be sufficiently developed to handle potentially high salt loads delivered in the food within hours after hatching (Douglas 1963, 1968). The purpose of this study was to determine the magnitude of salt loads received by chicks, determine if adults alter the salt composition of food given to chicks, and measure the salt concentrations of chick excretions (e.g. urine and salt-gland secretion) to determine salt-output capability. Adelie Penguins are good subjects for physiological studies of osmoregulation for four important reasons. First, their large size (adults weigh 4 to 5 kg) allows collection of relatively large samples of tissues and body fluids, which facilitates ion analyses. Second, Adelie Penguins are found in dense colonies near research 1 E-mail: donjanes@ucracl.ucr.edu stations in Antarctica, and this abundance combined with their relative tameness permits acquisition of large sample sizes. Third, their life history is well known (Ainley et al. 1983). Fourth, all of the material input into chicks is regurgitated by the parents, simplifying measurements of water and salt influx.

Anhomeostasis: Seasonal Water and Solute Relations in Two Populations of the Desert Tortoise (Gopherus agassizii) during Chronic Drought

Seasonal patterns of osmoregulation and water balance were compared in two populations of the desert tortoise (Gopherus [= Xerobates] agassizii) inhabiting portions of the Mojave Desert with different seasonal rainfall patterns. During an extreme drought year, tortoises lost as much as 40% of their initial body mass, and mean total body water volume decreased to below 60% of body mass. They stored wastes in, and apparently resorbed water from, their large urinary bladders. Osmolality of initially dilute bladder urine increased until it was isosmotic to blood plasma, after which osmolality of both fluids increased, eventually to some of the highest levels known for terrestrial reptiles. The increase in plasma osmolality comprised increases in plasma sodium, chloride, and especially urea concentrations. Bladder urine osmolality increased (owing primarily to soluble potassium) most rapidly during periods when tortoises ate annual plants; thus, their normal diet apparently was osmotically stressful. When rainfall events occurred, tortoises at both sites drank copiously, voided concentrated bladder urine, and stored dilute urine; body mass, total body water, and plasma and urine concentrations returned to hydrated levels. Drinking rainwater was as important for tortoises in the western Mojave, where summer rain is rare, as in the eastern Mojave, where it is predictable. Tortoises osmoregulate opportunistically, a tactic made possible by their capacity to tolerate temporary "anhomeostasis" and by extremely low rates of water loss (measured with isotopically labeled water). This opportunism resulted in wide, behaviorally based variation among individuals in all variables measured, as well as large differences (due to timing of rainfall) between populations and in temporal patterns between years within populations.

Use of Potassium and Sucrose by Onion Guard Cells during a Daily Cycle of Osmoregulation

Solute content of stomata from intact onion cotyledons grown under either greenhouse or growth chamber conditions was followed over the course of a daily light cycle to determine patterns of osmoregulation. Initial opening of stomata was well correlated with guard cell potassium accumulation under both growth conditions. Subsequently, however, there was a consistent decrease in guard cell potassium content despite constant or increasing aperture. Although a secondary increase in potassium was sometimes observed during the second half of the light cycle, guard cell potassium content was poorly correlated with aperture. Sucrose levels in guard cells increased 60% during the period of declining potassium content, suggesting its use as an alternate osmoticum. Guard cells are postulated to use multiple pathways for the production of osmotica over the course of a complete daily cycle of stomatal movements.

Changes in the pattern of osmoregulation in the brackish water amphipod Gammarus duebeni Lilljeborg (crustacea) during embryonic development

AbstractEggs of the gammarid amphipod Gammarus duebeni Lilljeborg were cultured in sterilised in vitro conditions over a range of external seawater concentrations. The osmoregulatory ability of embryos and newly hatched individuals cultured in these conditions was examined over a wide range of external concentrations (75‐1,250 mOsm·kg−1 at 15°C). For all of the developmental stages examined the isosmotic point of the periembryonic fluid, P.F. (fluid from the space between the embryo and the vitelline membrane) or haemolymph from newly hatched individuals was similar (500‐550 mOsm·kg−1). Regulation of the P.F. by early stage 2 and 3 embryos, characterised by reddening cephalothorax and limb bud development, and of the haemolymph by new hatchlings followed a hyper‐isosmotic regulation pattern. In dilute external concentrations (between 50 and 100 mOsm·kg−1) P.F./haemolymph was maintained at a concentration of approx. 400 mOsm·kg−1): This difference diminished with increasing external concentration so that at and above 500‐550 mOsm·kg−1 P.F./haemolymph and external concentrations were isosmotic. Maintenance of a hyperosmotic P.F. in dilute media maintains cell function and establishes the osmotic gradient required for the uptake of water that results in the characteristic swelling of embryos. P.F. osmolality was regulated before the appearance of the coxal gills possibly via the vitelline membrane and/or the dorsal organ. In contrast, P.F. from later, stage 5‐7 embryos (eye pigmentation and cardiovascular development but still pre‐hatch) showed a distinct hyper‐hypo‐osmotic pattern of regulation: In dilute media the P.F. was maintained at levels between 400 and 550 mOsm·kg−1, and at external concentrations above 550 mOsm·kg−1 the P.F. was less concentrated than the medium (a difference of > 350 mOsm·kg−1 in the most concentrated external media). The functional significance of this hyper‐hypo‐osmoregulatory pattern is unknown although its appearance may be associated with the appearance of the coxal gills and the subsequent degeneration of the dorsal organ. This study has demonstrated that osmoregulatory function changes with ontogeny in amphipods and that the most “complicated” pattern (hyper‐hypo‐regulation) is associated with late embryo rather than the most “complex” (adult) stage. © 1995 Wiley‐Liss, Inc.

Osmoregulation and salinity tolerance in zoeae and juveniles of the snow crabChionoecetes opilio

Osmoregulation and salinity tolerance were studied in zoeae 1 and instar IX juveniles of Chionoecetes opilio. In zoeae 1, the lower and upper lethal salinities for 50% of the animals (LS 50) at 14 °C were about 10 and 42‰ at 24 h, 18 and 41‰ at 48 h, 25 and 38‰ at 96 h. In juveniles, the approximate 48 h LS 50 s at 6 °C were 13.5 and 46‰. Both developmental stages are able to withstand relatively ample but brief variations of salinity. Their short-term euryhalinity is discussed in relation to the salinity of their habitat. Zoeae were hyper-osmoconformers. Juveniles were osmoconformers and isoionic to the external medium except for Mg++ which was hypo-regulated. Isosmotic and isoionic regulation in post-metamorphic stages are presumably an attribute of the family Majidae. The pattern of osmoregulation in zoeae 1 and juveniles relate C. opilio to the first of three groups of species previously characterized by their pattern of ontogeny of osmoregulation.

Daily Rhythms in Rates of Glomerular Filtration and Cloacal Excretion in Captive and Wild Song Sparrows (Melospiza melodia)

We infused polyethylene glycol (PEG) into laboratory-housed song sparrows (Melospiza melodia) via intraperitoneally implanted osmotic minipumps. The plasma concentration of PEG was significantly higher at the end of the dark phase of the photoperiod than at the end of light, indicating a nighttime reduction in the rate of glomerular filtration (GFR, the route of PEG elimination). The rate of cloacal voiding of PEG also varied through the day. The rate was similar to the rate of PEG infusion from the minipump during most of the daylight hours. However, PEG excretion was signifcantly reduced during the dark phase and elevated during the first hours of light, a pattern that resulted from sequestering urine in the lower intestine during the night. To examine patterns of osmoregulation in the field, we also implanted minipumps into free-living sparrows. One to fiue days later we recaptured the birds and measured concentrations of PEG in plasma and urine. As in the laboratory, the GFR (and urine flow rate) tended to be lowest in the early morning and higher later in the day. This nocturnal reduction in GFR and cloacal voiding should contribute to minimizing water losses during the night.

Osmoregulatory adjustments by three atherinids ( Leptatherina presbyteroides; Craterocephalus mugiloides; Leptatherina wallacei) to a range of salinities

1. 1. Patterns of osmoregulation were studied in three species of Swan river atherinids ( Leptatherina presbyteroides, lower estuarine and marine; Craterocephalus mugiloides, mid estuarine; Leptatherina wallacei, upper estuarine) over a wide range of salinities. 2. 2. The plasma Na + concentration was elevated with an increase in salinity. 3. 3. Haematocrit and body water content decreased with acclimation to higher salinity. 4. 4. All three species of atherinids osmotically regulated over a salinity range greater than that which these fish are reported to occur in.

Na +-K + ATPase and carbonic anhydrase activities in larvae, postlarvae and adults of the shrimp Penaeus japonicus (Decapoda, Penaeidea)

1. 1. Activities of Na +-K + ATPase and carbonic anhydrase were measured through the early post-embryonic development of Penaeusjaponicus. In adults, only the Na +-K + ATPase activity was measured. 2. 2. ATPase activity was variable in the successive development stages. From zero in nauplii, the activity slightly increased in zoeae, and rose sharply in mysis stages 2 and 3. 3. 3. A further significant increase in activity was noted at the transition from late mysis to early postlarvae, concomitant with a change from the larval osmoconforming pattern of osmoregulation to the postlarval and adult hyper-hyporegulating pattern. 4. 4. The activity of Na +-K + ATPase, measured in isolated cephalothorax, increased from PL3 to PL4 to its maximum value in PL5; at this stage, osmoregulatory capacity was fully efficient. 5. 5. In young stages of P. japonicus, the variations in Na +-K + ATPase activity appear correlated with the development of osmoregulatory ultrastructures, and with osmoregulation and salinity tolerance. 6. 6. These results are discussed with regard to their ecological and physiological implications. 7. 7. In adults, the activity of Na +-K + ATPase was high in gills and epipodites and no activity was detected in branchiostegites. These results are related to the ultrastructure of these organs. 8. 8. The activity of carbonic anhydrase did not change significantly in larval and postlarval stages. 9. 9. From these results, it is proposed that the effector sites of osmoregulation are located in branchiostegites, pleurae and epipodites in postlarvae, and in epipodites and mainly in gills in adults.

Osmotic and Ionic Regulation of Two Brine Fly Species (Diptera: Ephydridae) from a Saline Hot Spring

The brine fly Paracoenia calida Mathis is known only from the hot (source temperature = 54 C) saline (22 ppt) waters of Wilbur Hot Springs, Colusa Co., California. To investigate whether the high salinity is responsible for the endemic distribution of P. calida, I measured its hemolymph osmotic and ionic (sodium, chloride, potassium) concentrations and salinity tolerance (50% lethal exposure) of larvae exposed to a range of salinities (0-102 ppt) and water temperatures (15-40 C). Results were compared to similar measurements made on a co-inhabitant of P. calida, the geographically widespread brine fly Ephydra goedeni Wirth. In hypertonic waters (380-1,900 mM sodium chloride; 22-102 ppt) both species maintained their hemolymph hypoosmotic at concentrations between 150 and 350 mM NaCl regardless of water temperature. In hypotonic waters (0 and 25 mM NaC1), both species regulated their hemolymph hyperosmotic at 100 mM NaC1 regardless of water temperature. In contrast to their similar patterns ofosmoregulation, larvae of P. calida had an extremely low survivorship in deionized (0 mM NaC1) and diluted Wilbur Hot Springs water (7 mM NaCl; 1 ppt), whereas E. goedeni larvae exhibited their highest survivorship in deionized water. Paracoenia calida larvae in deionized water had high concentrations of K in their hemolymph. Perhaps this excess K leaked out from muscle and nervous tissues in response to declining hemolymph levels of Na and Cl; or the loss of K from these tissues may be an effect of cell death. Regardless, I suggest that P. calida is restricted to Wilbur Hot Springs because it cannot tolerate dilute salinities. In contrast, E. goedeni occurs throughout western North America in part because it can tolerate dilute salinities.

The pattern of osmotic regulation in larvae of the mosquito Culiseta inornata.

Larvae of Culiseta inornata (Williston) can survive and complete development in dilutions of sea water ranging from 50-700 mosmol kg-1. The larvae hyperregulate with regard to haemolymph osmotic concentration in dilute media (50-400 mosmol kg-1) and osmoconform when external salinities exceed 400 mosmol kg-1. This pattern of osmoregulation is distinct from that observed in freshwater and saline-water mosquito species. We propose that mosquitoes exhibiting this osmoregulatory pattern should be described as 'brackish-water' species. Larvae of Culiseta inornata are able closely to regulate both sodium and chloride ion concentrations in the haemolymph over the full range of salinities tested (50-750 mosmol kg-1). The Malpighian tubules produce an isosmotic, potassium-rich fluid. In vitro and in vivo sampling of rectal fluids demonstrates that rectal secretions are isosmotic or only slightly hyperosmotic to the haemolymph and the surrounding saline media, and that they are isotonic with regard to sodium.

The effect of a decrease in salinity on respiration, Osmoregulation and activity in the shore crab,Carcinus maenas (L.) at different acclimation temperatures

1. The rates of oxygen consumption (\(\dot V_{{\text{O}}_2 } \)) of individual crabs varied with their live mass. Mean\(\dot V_{{\text{O}}_2 } \) increased with acclimation temperature in 100% seawater (Q10 2.36) but not in 50% seawater. 2. Exposure to 50% seawater caused a significant increase in\(\dot V_{{\text{O}}_2 } \) to twice the rate in 100% seawater at 10°C. There was no significant increase in\(\dot V_{{\text{O}}_2 } \) on dilution at 18°C (Fig. 5). 3. Heart rate, ventilation volume (\(\dot V\)) and a-VO2 content difference were unaffected by dilution. The rise in\(\dot V_{{\text{O}}_2 } \), following dilution at 10°C may, as far as the cardiovascular system is concerned, arise from an increase in cardiac stroke volume. 4. Crabs were isosmotic with 100% seawater at 10°C, 14°C and 18°C. In 50% seawater all crabs showed a significant reduction in blood osmolarity, though they maintained the ΔF.p. and Na+ concentration significantly above that of the medium. Crabs acclimated to 10°C maintained a significantly higher blood ΔF.p. and Na+ concentration in 50% seawater than crabs at 18°C (Fig. 6). 5. Crabs acclimated to 10°C were significantly more active after exposure to 50% seawater. There was no significant change in activity, following dilution, in crabs at 18°C (Fig. 7). 6. The variations in\(\dot V_{{\text{O}}_2 } \) with temperature and salinity seem to relate to the measured changes in patterns of osmoregulation and activity. At 10°CCarcinus osmoregulates more effectively than at 18°C and is hyperactive in low salinities, which may represent an avoidance reaction. At 18°C, the summer temperature, the crab tolerates internal dilution and is relatively quiescent.

Osmoregulation and differential penetration of two grey mullets, Chelon labrosus (Risso) and Liza ramada (Risso) in estuarine fish ponds

Grey mullet ponds situated in Arcachon Bay on the western Atlantic coast of France, display contrasting mixohaline habitats. The pattern of osmoregulation of Chelon labrosus and Liza ramada exhibiting differential penetration of fish ponds has been investigated. Key variables of salinity and temperature have been considered. The tolerances to low salinities and to fresh water have been determined. The dynamics of variation in plasma osmotic pressure and major plasma electrolytes (Na +, Cl −, K +) were studied in terms of: (1) gradual adaptation to a decreasing salinity gradient; (2) effects of a long-term adaptation in fresh water; (3) effects of low temperatures on sea water adapted fish. Both species can adapt to a wide range of salinities; however, while L. ramada show a good hypoosmotic regulation, with no alteration in plasma concentration over a wide range of salinity and after a long stay (5 months) in fresh water, C. labrosus cannot live for long periods of time in a wholly fresh water habitat. Both field samples obtained from thick-lipped grey mullets forced to stay in a freshwater pond and experimentally adapted fish showed, after 3 months, an unequivoqual decrease in plasma sodium and chloride, and plasma osmolality decreased to the same extent; this pattern of no compensation is bound, sooner or later, to end in death. The inability of C. labrosus to develop a long-term hypoosmoregulation in fresh water is referred to salinity preferences which probably limit the upstream penetration of this species. Plasma osmolality and major electrolytes (sodium and chloride) increased in cold (4 °C) sea water. This response might be due to a reduced ability of grey mullets to osmoregulate in cold waters. In the poly-mesohaline ponds, Winter drop in temperature (4–6 °C) causes grey mullets to migrate to the meso-oligohaline ponds where the mean temperature is more elevated (8 °C) and temperature changes less rapid (6–9 °C).

A Re-Examination of the Functional Morphology of the Soft-Rays in Teleosts

SCHOLANDER, P. F., L. VAN DAM, J. W. KANWISHER, H. T. HAMMEL, AND M. S. GORDON. 1957. Supercooling and osmoregulation in arctic fish. J. Cell. Comp. Physiol. 49:5-24. STROGANOV, N. S. 1939. Acclimatization of Gambusia in north latitudes. The action of temperature upon the interrelation of processes of gas and nitrogen metabolism in Gambusia broockii. Uchenye Zapiski MGV 33:30-45. ToEws, D. P., AND C. P. HICKMAN, JR. 1969. The effect of cycling temperatures on electrolyte balance in skeletal muscle and plasma of rainbow trout Salmo gairdneri. Comp. Biochem. Physiol. 29:905-918. UMMINGER, B. L. 1969a. Physiological studies on supercooled killifish (Fundulus heteroclitus) I. Serum inorganic constituents in relation to osmotic and ionic regulation at subzero temperatures. J. Exp. Zool. 172:283-302. . 1969b. Physiological studies on supercooled killifish (Fundulus heteroclitus) II. Serum organic constituents and the problem of supercooling. Ibid. 409-424. . 1971a. Osmoregulatory role of serum glucose in freshwater-adapted killifish (Fundulus heteroclitus) at temperatures near freezing. Comp. Biochem. Physiol. 38A:141-145. . 1971b. Patterns of osmoregulation in freshwater fishes at temperatures near freezing. Physiol. Zool. 44:20-27.

Patterns of Osmoregulation in Freshwater Fishes at Temperatures near Freezing

Patterns of Osmoregulation in Freshwater Fishes at Temperatures near Freezing

Osmotic regulation and urea metabolism in the lemon shark Negaprion brevirostris.

Osmotic regulation and urea metabolism in the lemon shark Negaprion brevirostris.

Osmotic Regulation in the Tadpoles of the Crab-Eating Frog (Rana Cancrivora)

ABSTRACT Salinity tolerance, osmoregulatory mechanisms and some effects of salinity on embryonic development and metamorphosis have been studied in the tadpoles of the euryhaline crab-eating frog (Rana cancrivora). Tadpoles in developmental stages III-XIX survive well in all salinities from fresh water to 32% sea water. They are good osmoregulators over this entire range, plasma osmotic concentration changing by only 250 m-osmoles/1. in the face of environmental concentration changes of 900 m-osmoles/1. Na, Cl, and K account for over 90% of plasma osmotic concentration in all external concentrations. The osmoregulatory mechanisms used by the tadpoles appear to be similar to those used by euryhaline teleost fishes. In hyperosmotic media they probably drink, then excrete salts by an extrarenal pathway. A metamorphosis in osmoregulatory mechanisms occurs simultaneously with morphological metamorphosis. The osmoconforming behaviour of adult frogs is fully developed in the tadpoles by developmental stage XXV. As in other anuran species there probably is no significant urea production before metamorphosis. Both early embryonic development and the completion of metamorphosis beyond stage XIX apparently require low salinities. The pattern of osmoregulation shown by tadpoles of the freshwater R. limno-charis is identical with osmoregulatory patterns found in adult freshwater anurans. Evolutionary and ecological impheations of the data are discussed.