Lars Hagerman

Haemocyanin concentration in the shrimp Crangon crangon (l.) after exposure to moderate hypoxia

Abstract 1. 1. The brown shrimp Crangon crangon was kept under normoxia and moderate (40% saturation) hypoxia. Haemocyanin concentrations were measured and the data segregated according to moult stage of the animals. 2. 2. The mean, normoxic haemocyanin concentration was 0.5–0.6 mM·l −1 for intermoult animals and this increased to 0.8 mM·1 −1 and 1.3mM·1 −1 after 1 and 2 weeks hypoxia, respectively. 3. 3. During the moult cycle, haemocyanin concentration varied in normoxia from 0.3 mM · 1 −1 (stage A) to 0.75mM·1 −1 (stage D 3 ). 4. 4. Haemocyanin was synthesized under hypoxia in all moult stages at about 5–6% of the normoxic mean value per day. 5. 5. Starved Crangon showed a rapid drop in haemocyanin levels.

The oxygen consumption of Crangon vulgaris (Fabricius) (Crustacea, natantia) in relation to salinity

Abstract The oxygen consumption rate (OCR) of the sand-living Crangon vulgaris was measured at various temperatures and salinities. Starvation was found to have no influence on resting OCR, while the active OCR was steadily decreasing. In the temperature range 0–20°C the Q10 was between 2.5 and 3.6, i. e. within the normal range for crustaceans. The OCR was compared for animals weighing 100 ± 10 mg and 200 ± 20 mg (wet weight) at various salinities at the temperatures +6, 13 and 20°C. At all temperatures OCR was found to increase at salinities lower than about 20%, and at +6 and +13°C it also increased at higher salinities, while no significant increase at higher salinities was found at +20°C. It is suggested that this OCR pattern reflects the osmo-regulatory work, as Crangon is a homoiosmotic animal with isotony in 21–23%. Only a small part of the respiratory increase is caused by higher activity at high and low salinities.

Aspects of blood physiology and ammonia excretion in Nephrops norvegicus under hypoxia

Abstract 1. 1. Circulating haemocyanin, glucose, lactate, and ammonia concentrations and ammonia excretion rates of Nephrops norvegicus were studied in normoxia and in various hypoxia levels for periods up to 3 weeks. 2. 2. Increases in circulating glucose and lactate took place in oxygen tensions PwO2; = 3. 3. In moderate hypoxia (half saturation), N. norvegiens synthesised haemocyanin; in more severe hypoxia some haemocyanin catabolism occurred. 4. 4. Mean normoxic blood ammonia concentration was 130 μM NH+4/1 with large individual variation. Blood ammonia levels decreased with time in both normoxia and hypoxia showing a lowered metabolic rate (activity level) over the experimental period. In short term experiments, blood ammmonia levels decreased in hypoxia. 5. 5. Mean ammonia excretion rate was O.16μ M NH+4 g/wet wt/hr under normoxia and excretion rate showed a negative, linear relationship to external oxygen tension.

Locomotory activity patterns of Crangon vulgaris (fabricius) (crustacea, natantia)

Asbtract The diellocomotory rhythm of Crangon vulgaris from a non-tidal area was investigated by means of photocells. Crangon was found to be nocturnal with the light-dark change acting as a Zeitgeber. The activity level did not change significantly during the year, but the activity pattern changed considerably. In winter (nLD 8: 16) Crangon showed two or three activity peaks, in summer (nLD 17: 7) only one. It was possible to shift the period of activity to any time of the day by displacing the dark period. If the lighted period was prolonged to more than 22 hours Crangon showed a phase-shift to a diurnal activity. At the same time the level of activity decreased markedly. No free-running rhythm persists in constant darkness. The rhythm was shown to be of a fully external origin. Certain environmental conditions, for instance the absence of a correct substratum, completely break down the rhytm. Such conditions exert a stronger influence than the Zeitgeber.

The toxicity of chromium, nickel and zinc: effects of salinity and temperature, and the osmoregulatory consequences in the mysid Praunus flexuosus

Abstract The effect of salinity (4.5–27ℵ) and temperature (5 and 15°C) on the acute toxicity of chromium, nickel and zinc to the mysid crustacean Praunus flexuosus (Muller) has been investigated, at time intervals up to 300 h. Increased metal concentration led to reduced median survival time. Increased temperature, and salinities above or below the isosmotic point, led to reduced median survival times at a given metal concentration and reduced median lethal concentrations of metals. The effect of salinity on metal toxicity has been clearly linked to disruption of the normal pattern of hyper/hypoosmoregulation. The death of animals in chromium or zinc solutions may be related to a progressive decrease in the ability of the animals to osmoregulate, with the rate of osmotic decline related to the median survival time, or the loss of osmoregulatory ability may be a secondary effect of metal poisoning and dying. Nickel was found to be less toxic than either chromium or zinc and to have less effect on osmoregulation.

Nephrops norvegicus: field study of effects of oxygen deficiency on haemocyanin concentration

Abstract A 2-month period of oxygen deficiency occurred in parts of the southern Kattegat during the late summer of 1986, and was accompanied by commercial catches of Nephrops which included dead, moribund, and pale-coloured animals. Haemocyanin levels in live animals at this time were very low when compared with a representative population sampled off eastern Scotland. It is contended that the hypoxia affected the feeding activity of Nephrops and that the resulting starvation induced the low haemocyanin values. Such events have been observed elsewhere in laboratory studies. In some of the sampling areas, population haemocyanin levels recovered following the return to normoxic conditions after autumnal storms.

Respiratory rate, haemolymph oxygen tension and haemocyanin level in the shrimp Palaemon adspersus: Rathke

The marine shrimp Palaemon adspersus Rathke, frequenting Zostera meadows, shows an oxygen consumption rate (MO2) that is independent of water oxygen tension (PwO2) as PO2 decreases to a critical point (Pcr) near 70 mm Hg. This respiratory independence is associated with maintenance of a relatively constant “arterial” (post-branchial) haemolymph tension (PaO2) at 70–80 mm Hg. At lower PwO2 values, both MO2 and PaO2 fall, reflecting, in contrast to the above independence, a direct dependence of MO2 on internal PO2. Haemolymph copper measurements demonstrate relatively high haemocyanin concentrations and oxygen-carrying capacities, but MO2 levels reflect an insignificant role for the pigment as an oxygen store. The data are discussed as regards adaptations for aerobic metabolism.

Oxygen and carbon dioxide transporting qualities of hemocyanin in the hemolymph of a natant decapodPalaemon adspersus

Summary1.The O2 and CO2 combining properties ofPalaemon adspersus hemolymph is studied, aiming to assess respiratory function and the environmental and metabolic adaptations of hemocyanin of natant decapods where, in contrast to the intensively-studied, larger and predominantly less active reptant decapods, virtually no information is available.2.The hemolymph shows a high O2 carrying capacity (mean=2.8 vol%), a low O2 affinity (at 15 °C half-saturation tension,P50=16 and 37 mm Hg at pH 7.85 and 7.65, respectively), pronounced cooperativity in O2 binding (Hills coefficient,n≃2.8) and a large, pH dependent Bohr factor (ϕ=ΔlogP50/ΔpH=−2.0 and −0.9 at pH 7.85 and 7.4, respectively) (Figs. 1 and 2). These qualities are distinct from those typifying reptant hemocyanins and appear illsuited for O2 transport at low ambient tensions, but well-adapted for O2 delivery in tissues at highPO2, supporting high levels of metabolism and activity.3.CO2 has a specific, augmenting effect on O2 affinity at high pH (Fig. 3), indicating carbamate formation with an opposite oxygenation-linkage as in vertebrate hemoglobins. Astrup titrations indicate the presence of a small but distinct Haldane effect at physiological pH, and buffering capacity varies greatly (ΔHCO3/ΔpH≃−4.4 to −9.3 mmol·1−1·(pH unit)−1 depending on hemocyanin concentration) (Fig. 4). Equilibrium curves of total, non-protein-bound CO2 show large capacitance for transport at low, in vivo CO2 tensions (Fig. 4).4.The data are discussed comparatively, particularly as regards hemocyanin function in reptant decapods, and the O2, CO2 and proton exchanges involved.

Effects of hypoxia on osmotic and ionic regulation in the brown shrimp Crangon crangon (L.) from brackish water

When exposed to hypoxia (PwO2, <Pcr) and low salinity conditions, the shrimp, Crangon crangon (L.) shows a progressive loss of blood chloride until a new, stable value, still higher than that of the medium, is reached. Simultaneously, circulating levels of calcium progressively increase. Under identical experimental conditions, circulating levels of sodium and magnesium and the blood total osmolarity (Δ °C) are unchanged. The possible explanations for such changes are considered along with their adaptive significance.

Haemocyanin concentration, carrying capacity and haemolymph pH under hypoxia in Mesidothea entomon (L.) (isopoda, crustacea)

Abstract The haemocyanincontaining blood of the isopod Mesidothea entomon was investigated with regard to changes in the concentration of haemocyanin, carrying capacity (Hcy + dissolved O2) and pH under hypoxia of 10–20 torr for up to 96 h. Normoxic Hcy concentration was 0.79 mM · l−1 and after 96 h hypoxia this increased to 1.17 mM · I−1, carrying capacity changed correspondingly from 1.8 vol% to 2.19 vol%. The physically dissolved oxygen was negligible. Haemolymph pH for Mesidothea under normoxia was 7.646 at 10°C and this increased to 7.909 after 96 h under hypoxia. The results are discussed in relation to the ecology of the species.