Evidence for a permanent establishment of the snow crab (Chionoecetes opilio) in the Barents Sea

In the Atlantic the snow crab (Chionoecetes opilio) is naturally distributed on the northwestern side, i.e. eastern Canada and west Greenland. Until recently, there have been no observations of snow crab in eastern Atlantic. However, in 1990s single and occasional reports were made of crabs captured in the eastern part of the Barents Sea, presumably introduced through ballast water. Special attention during the annual bottom-trawl surveys in the Barents Sea during February 2004–2006 were given to include recordings of snow crab to evaluate if the introduced species has succeeded to establish a self-sustaining population in this region. Recordings of snow crabs were systematically noted and biological measurements carried out. The results confirm previous Russian observations of snow crabs in the northern region of Gåsebanken. In addition, a significant number of crabs were also found in the central region of the Barents Sea, mainly in deeper waters from 180 to 350 m depth. The sizes ranged from 14 to 136 mm carapace width. All females above 70 mm were berried with fertilised eggs. A major fraction (31% in 2005; 76% in 2006) of the crabs consisted of juveniles below 50 mm CW, providing evidence for successful recruitment. The small-sized crabs were exclusively found in Gåsebanken, identifying the main recruiting area at present for snow crab in the Barents Sea. The results obtained show that the snow crab is now adapted to the northeast Atlantic.     

Effect of Eyestalk-Ablation on Circulating Ecdysteroids in Hemolymph of Snow Crabs, Chionoecetes opilio: Physiological Evidence for a Terminal Molt

Bering Sea snow crabs (Chionoecetes opilio) are a commerciallyimportant crab harvested in the Bering Sea. Optimal managementof this species requires an understanding of the biology ofthis crab that is currently incomplete. Fisheries managers applya continuous growth model in their management of snow crab,which assumes that male crabs increase in size throughout theirlifespan. Male snow crabs undergo a morphometric molt that leadsto a disproportionate increase in chelae size and it is stilldebated whether this molt is associated with a terminal molt.This study was conducted to determine whether adult male C.opilio are anecdysic. Using current knowledge of the hormonalregulation of crustacean growth, snow crab physiology was manipulatedto induce an increase in molting hormones (ecdysteroids). Sincefemale snow crabs are known to undergo a terminal molt afterattaining reproductive maturity, we compared ecdysteroid levelsin eyestalk-ablated terminally molted females, small-clawedmales and large-clawed males. Snow crabs were collected fromthe Bering Sea and maintained in circulating seawater at approximately6°C. Animals were either eyestalk-ablated or left intact.Ecdysteroid levels in hemolymph were quantified using an enzyme-linkedimmunosorbant assay (ELISA). Circulating ecdysteroids were significantlyhigher in small-clawed male crabs when compared to large-clawedmales or terminally molted females. Eyestalk-ablation increasedcirculating ecdysteroids in small-clawed males, but had no significanteffect on circulating ecdysteroids in large-clawed males orin terminally molted females.     

Der Einfluß der Umgebungstemperatur auf Motilität,Körpertemperatur und Sauerstoffverbrauch von normalen und Pervitin-behandelten Mäusen

Single mice were kept in various ambient temperatures (15° to 35° C) and motility, oxygen consumption, and body temperature were recorded. Untreated animals: Motility was least at 25° C room temperature. Relations between motility and body temperature were linear at all ambient temperatures. The body temperatures of very agile mice did not vary at ambient temperatures from 15° to 30° C whereas that of quiet mice was strongly influenced by the milieu. The relations between oxygen consumption and body weight were also linear at all ambient temperatures; the corresponding regression coefficients decreased progressively with rising ambient temperatures. Oxygen consumption increased at a constant rate with motility, independent of ambient temperatures. Animals treated with methamphetamine: The LD₅₀ of methamphetamine decreased considerably with rising ambient temperature. The influence on body temperature of methamphetamine was very variable and depended on both dose and ambient temperature. Toxic doses of methamphetamine induced hyperthermia in warm surroundings and hypothermia in a cool milieu. Under the influence of methamphetamine, oxygen consumption increased or decreased considerably with the body temperature. Ambient temperatures exerted an essential influence on the cause of death after toxic doses of methamphetamine.     

Broad thermal capacity facilitates the primarily pelagic existence of northern fur seals (Callorhinus ursinus)

Thermoregulatory capacity may constrain the distribution of marine mammals despite having anatomical and physiological adaptations to compensate for the thermal challenges of an aquatic lifestyle. We tested whether subadult female northern fur seals (Callorhinus ursinus) experience increased thermoregulatory costs in water temperatures potentially encountered during their annual migration in the Bering Sea and North Pacific Ocean. Metabolic rates were measured seasonally in 6 captive female northern fur seals (2.75–3.5 yr old) in ambient air and controlled water temperatures of 2°C, 10°C, and 18°C. Rates of oxygen consumption in ambient air (1°C–18°C) were not related to environmental temperature except below 2.5°C (winter only). However, metabolism was significantly higher during the fall seasonal trials (September–October) compared to other times of year, perhaps due to the costs of molting. The fur seals appeared thermally neutral in all seasons for all water temperatures tested (2°C–18°C) except during the summer when metabolic rates were higher in the 2°C water. Comparing this broad thermal neutral zone to the average sea surface temperatures potentially encountered during annual migrations indicates wild fur seals can likely exploit a large geographic area without added thermal metabolic costs.     

Hypothermal effects on survival,energy homeostasis and expression of energy-related genes of swimming crabs Portunus trituberculatus during air exposure

Previously, dry or semi-dry approach under the hypothermal condition is proved to be an alternative method in transport of live swimming crabs Portunus trituberculatus. However, we wondered whether this method can improve crab survival when temperature is kept as cool as possible. In this study, we hypothesized that there is a thermal threshold below which dry or semi-dry approach (air exposure) could cause crab physiological disruption and therefore aggravate their mortality. To test the above hypothesis, crabs (23 °C) were exposed to air at temperatures ranging from 4 to 16 °C. Results showed that crabs had a worse survival and vigor at temperatures below 12 °C. Then we tested crab energy metabolism to explore the possible reason. It was shown that total adenine nucleotide and adenylate energy charge in gills were remarkably reduced by air exposure of below 12 °C. This increased the need for crabs to re-balance energy metabolism, which was indicated by the upregulation of AMPKα and HIF-1α. Meanwhile, there was a significant increase of the expression of Na⁺/K⁺-ATPase, V-type ATPase and HSP90 at temperatures below 12 °C, while all treatments shared a similar level of hemocyanin, urate and lactate in hemolymph and expression of cytochrome c oxidase and NADH-ubiquinone reductase in gills. These results implied that dry or semi-dry approach below 12 °C could exert detrimental effects on P. trituberculatus, and perturbation of energy homeostasis, which is more related with changes of energy-demanding physiological pathways, is a possible reason of crab death and poor vigor.     

Entrainment of the circadian rhythm in larval release of the crab Dyspanopeus sayi by temperature cycles

Marine and estuarine crabs brood attached eggs, which hatch synchronously releasing larvae at precise times relative to environmental cycles. The subtidal crab Dyspanopeus sayi has a circadian rhythm, in which larvae are released within the 4-h interval after the time of ambient sunset. Previous studies demonstrated that the rhythm can be entrained by the light:dark cycle. Since subtidal crabs are also exposed to temperature fluctuations, an unstudied question was whether the circadian rhythm could be entrained by the diel temperature cycle. To answer this question, ovigerous D. sayi were entrained in darkness to 2.5, 5, and 10 °C temperature cycles that were reverse in phase from the ambient temperature cycle. After entrainment, larval release times were monitored in constant conditions of temperature and darkness with a time-lapse video system. The effectiveness of a temperature cycle to shift the timing of larval release increased as the magnitude of the temperature cycle increased and as crabs were exposed to increasing numbers of entrainment cycles. However, entrainment to a 10 °C cycle only lasted 2 days in constant conditions. When crabs were entrained to a light:dark vs. a 10 °C temperature cycle, the light:dark cycle was dominant for entrainment. Nevertheless, ovigerous crabs do sense temperature cycles and in areas where daylight is too low for entrainment, temperature cycles can be used to regulate the time of larval release.     

Short‐term effect of hypoxia on ammonia excretion and respiration rates in the crab carcinus maenas

The metabolic response of the crab Carcinus maenas to short‐term hypoxia (60% and 35% saturated seawater) was studied at 17.5°C in fed, 3 day‐unfed and 6 day‐unfed crabs.

Ammonia excretion rate decreased under hypoxia: a 40% and 45% decrease in the normoxic rate was observed in fed crabs at 35% saturation and in 3 day‐unfed crabs at both hypoxic levels respectively. In the 6 day‐unfed crabs, the effect of hypoxia was concealed by the effect of starvation.

Oxygen consumption rate was directly related to the external O₂ tension irrespective of the crab's nutritional state. Stressed crabs behaved as a whole, as oxygen‐conformers.

A strong relationship was observed between ammonia excretion and oxygen consumption rates in fed crabs under hypoxia but not in starved crabs.     

On the growth of the blue king crab (<Emphasis Type="Italic">Paralithodes platypus</Emphasis>) population in the Peter the Great Bay of the sea of Japan

The causes of the appearance of large blue king crabs (Paralithodes platypus) in Peter the Great Bay for the last decade are discussed. This species is an important commercial resource in the waters of Russian Far Eastern seas, and its general concentrations are related mainly to the sublittoral and upper bathyal zones of the northwestern Bering Sea and the northern Sea of Okhotsk. Until recently, this species has been observed in areas along the continental coast of the northwestern Sea of Japan up to the Peter the Great Bay, where it incidentally showed up in red king crab (P. camtschaticus) and snow crab (Chionoecetes opilio) catches but was also commercially used. This area was considered as the southern periphery of the species range. Since the late 1990s, both male and female blue king crabs have been recorded in trawl and trap catches during research works conducted within the Peter the Great Bay. Since 2002, any commercial catches of shelf crab species are prohibited in the waters south of 47°20′ N because of a dramatic decline in their populations. Since then all the illegally caught crabs, including blue king crabs that are seized live from poachers, are released back into the water in certain places of the bay. In total, at least 29 503 blue king crabs, including egg-bearing females, were released within the period from 2002 to November 2009. At present, the overall blue king crab abundance in Peter the Great Bay, estimated based on the trap catches over an area of 7048 km², is 50500, the abundance of commercial-size males (with a carapace width over 130 mm) is 7500, and the male to female ratio is 1.00: 1.35. The increase in the blue king crab population observed in the bay is the result of the immigration of mature and viable individuals from other areas of its range. After this “uncontrolled introduction” blue king crabs adapted to new conditions, and then began breeding and spreading over the entire area of the bay.     

The period of occurrence,density, and distribution of larvae of three commercial crab species in Peter the Great Bay,Sea of Japan

Based on materials from plankton surveys carried out in 2004–2009, the period of occurrence, density, and distribution of larvae of three commercial species of crabs in the Peter the Great bay and adjacent areas of Sea of Japan were studied. The larvae of the horsehair crab Erimacrus isenbeckii (Brandt, 1848) occurred in the plankton from mid-March to early June, within the range of water temperature from −1 to 10.8°C. The larvae of the helmet crab Telmessus cheiragonus (Tilesius, 1812) appeared in the plankton in mid-April and occurred to the end of June within the temperature range from 2.8 to 13.0°C. The larvae of the snow crab Chionoecetes opilio (O. Fabricius, 1788) appeared in the plankton in mid-April as well, but some individuals sporadically occurred until early August. All the species of crabs produced one generation of larvae for their reproduction season. The terms of larval stay in plankton depended on water temperature and the duration of the pelagic period increased in colder years. In that area, the larvae of C. opilio were the most abundant (up to 41 ind./m³) and the zoea density of horsehair and helmet crabs was significantly lower (no more than 2 ind./m³). The larvae of C. opilio occurred over the entire area of the Peter the Great bay; the greatest aggregations of their early stages were observed in its southwestern open part. The maximum density of E. isenbeckii zoea was recorded in the south of the Amursky bay and in the Posyet bay. Individual larvae of T. cheiragonus occurred in the Posyet bay and in the southern part of the Amursky and Ussuriisky bays. The late-stage larvae of all crab species were concentrated in areas of the coastal circulation.     

Effects of temperature on oxygen consumption and heart rate in the semi‐terrestrial crab,Ocypode sa ratan (Forskål)

The effect of temperature on the rate of oxygen consumption and heart rate has been investigated in the Red Sea, semi‐terrestrial crab, Ocypode saratan. The Q₁₀ values for both oxygen consumption and heart rate were often <2 and were relatively constant over a wide range of temperature. This suggests that O. saratan is well adapted for life in a high temperature environment. It was noted, however, that behavioural mechanisms were important in reducing the degree of temperature stress that could be experienced in the field. The rates of oxygen consumption of immersed crabs were significantly lower than those of crabs maintained in air at the same temperature.     

Effects of Temperature and Water Loss on Terrestrial Locomotor Performance in Land Crabs: Integrating Laboratory and Field Studies

SYNOPSIS. Terrestrial and semi-terrestrial crustaceans are exposedto fluctuations in ambient temperature and conditions that favorevaporative water loss. These environmental stresses alter performancelimits in the laboratory and behavior in the field. The maximalrate of oxygen consumption, maximum aerobic speed, and endurancecapacity are greater at a body temperature (T_b) of 24°Cthan at 15°C or 30°C in the ghost crab, Ocypode quadrata.The total metabolic cost to move at the same relative speedis greater at a T_b of 24°C than at 15°C. Slower aerobickinetics at 15°C result in a smaller relative contributionof oxidative metabolism to total metabolic cost. However, therelative contributions from accelerated glycolysis are similarat both temperatures. When locomotion is intermittent, the totaldistance traveled before fatigue can be similar at Tbs of 15and 24°C but result from different movement and pause durationsat these temperatures. Performance limits of the ghost crabare negatively affected by dehydration and are sensitive torates of water loss. In the laboratory, endurance capacity ofthe fiddler crab, Uca pugilator, is greater at a T_b of 30°Cthan at 25°C. In the field, freely moving fiddler crabswith a T_b of 30°C travel at faster mean preferred speeds,as determined by motion analysis, than crabs at 25°C. Datafor land crabs support and advance general ectothermic modelsfor the effects of temperature and dehydration on locomotorperformance.     

Red king crab (<Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis>) fisheries in Russian waters: historical review and present status

The red king crab (Paralithodes camtschaticus) is a highly valued delicacy on the international market and currently contributes significantly to the income from fisheries in the regions where it is harvested. Russian income from red king crab export is $200–250 million per year. We review both the biology and fishery of the two largest populations of this species in Russia, i.e., in western Kamchatka (Sea of Okhotsk) and in the Barents Sea. The latter was established in the mid-1990s after introduction of red king crab to the area in the 1960s. The Barents Sea crabs are larger, grow faster and mature earlier than the crabs from the Sea of Okhotsk owing to more favorable temperature conditions in the Barents Sea. Additionally, we provide fishery information for the Prymorie population of red king crab (Sea of Japan) that remains depressed and closed for commercial fishery at present. Although the fishery period of red king crab in western Kamchatka is much longer than in the Barents Sea (1930–present time vs. 2004–present time), similar patterns were observed for the exploited king crab populations. High annual landings led to a pronounced decrease in population density and total abundance that, in turn, led to closures or some limitations of fisheries. Subsequent rehabilitations of the populations provided an opportunity for reopening of the fisheries and further exploration of red king crab populations under sustainable management. The main reason explaining a decline in red king crab populations both in the North Pacific and in the Barents Sea is high, mainly illegal, fishing pressure. Sustainable harvest strategies for the fisheries could prevent negative scenarios (overfishing) in the future.     

Size variations in temperature effects in carcinus maenas

The wet wt/O₂ consumption of Carcinus maenas (L.) was examined under natural conditions. Freshly collected crabs were measured in five sets of experiments made at ambient temperatures, using two locations in Ireland and one in France.

When comparing locations, oxygen consumption bears no relationship to temperature but appears to be a function of local conditions, or local races.

Wicklow crabs measured at ambient temperatures of 9°, 11°, and 16°C exhibited a size effect. Ten g crabs were not affected by temperature, but 60g crabs had a Q₁₀ of 1.5 (mean rates).

Variations increased with temperature, a potential source of misinterpretation of a standard rate independent of temperature. Biological rhythms may produce this variation. It is important to know the behavioural state of animals during experiments.

Overall, temperature appears to have little effect upon crabs under natural conditions.     

Thermoregulation in the primitively eusocial paper wasp, Polistes dominulus

Regulation of wing muscle temperature is important for sustaining flight in many insects, and has been well studied in honeybees. It has been much less well studied in wasps and has never been demonstrated in Polistes paper wasps. We measured thorax, head, and abdomen temperatures of inactive Polistes dominulus workers as they warmed after transfer from 8 to ~25°C ambient temperature, after removal from hibernacula, and after periods of flight in a variable temperature room. Thorax temperature (T _th) of non-flying live wasps increased more rapidly than that of dead wasps, and T _th of some live wasps reached more than 2°C above ambient temperature (T _a), indicating endothermy. Wasps removed from hibernacula had body region temperatures significantly above ambient. The T _th of flying wasps was 2.5°C above ambient at T _a = 21°C, and at or even below ambient at T _a = 40°C. At 40°C head and abdomen temperatures were both more than 2°C below T _a, indicating evaporative cooling. We conclude that P. dominulus individuals demonstrate clear, albeit limited, thermoregulatory capacity.     

Epibionts of the red king crab Paralithodes camtschaticus (Tilesius, 1815) in Sayda Inlet of Kola Bay

The species composition of organisms associated with the red king crab Paralithodes camtschaticus (Tilesius, 1815) was investigated in Sayda Inlet of Kola Bay in 2004–2005. Nine fouler species and three symbiotic species were found on the carapaces of the red king crab. Balanus crenatus Bruigere 1789 barnacles were the most abundant fouler species and were found on 14.8% of the crabs. Symbiotic amphipods Ischyrocerus commensalis Chevreux, 1900 were found for one-tenth of all the crabs studied. The mean intensity of the amphipods was significantly greater for September, when the reproduction period of this species occurred. Male and female crabs were hosted with the same intensity. The number of host crabs increased accordingly to the crab size. The proportion of hosted crabs was three-fold less in Sayda Inlet than in the less polluted areas of the Barents Sea.     

Walking speed and area utilization of red king crab (<Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis>) introduced to the Barents Sea coastal ecosystem

The red king crab (Paralithodes camtschaticus) was introduced in the Barents Sea in the 1960s and soon established a viable population. Proper management and exploitation of the Barents Sea king crab stock require better understanding of the spatial dynamics at different scales. This study examines the small-scale movement patterns of seven adult male crabs tracked for a period of up to one month from mid July to mid August at 150 m depth in a semi-enclosed fjord on the Russo-Norwegian border. The crabs were tagged with acoustic transmitters and their movements monitored with an acoustic positioning system. Low walking speeds (<0.01 m s⁻¹) were most frequent but the crabs could move at a maximum speed of 0.15 m s⁻¹ and walk an actual distance of up to 270 m over a period of one hour. However, the crabs usually moved within a relatively restricted area with mean hourly longest rectilinear distance varying from 26 to 64 m. The crabs alternated between periods of low and high activity, which could reflect feeding in and movements between food patches. The lack of a diel activity rhythm may be due to high light levels during the polar summer night, or a chemically mediated food search strategy.     

At the tipping point: Differential influences of warming and deoxygenation on the survival,emergence, and respiration of cosmopolitan clams

Although warming and low dissolved oxygen (DO) levels are co‐occurring significant climatic stressors in the ocean, the combined effects of these stressors on marine benthic animals have not been well established. Here, we tested the effects of elevated temperatures and low dissolved oxygen levels on the survival, emerging behavior from sediment, and the respiration of juvenile cosmopolitan Manila clams (Venerupis philippinarum) by exposing them to two temperatures (20 and 23.5°C) and DO levels (3.5 and 6–7 mg/L). Although within previously described tolerable ranges of temperature and DO, this 3.5°C increase in temperature combined with a 50% decrease in DO had a devastating effect on the survival of clams (85% mortality after 8 days). The mortality of clams under normoxia at 23.5°C appeared to be higher than under the low DO condition at 20°C. On the other hand, more clams emerged from sediment under the low DO condition at 20°C than under any other conditions. Oxygen consumption rates were not significantly affected by different conditions. Our results suggest temperature elevation combined with low oxygen additively increases stress on Manila clams and that warming is at least as stressful as low DO in terms of mortality. However, low DO poses another threat as it may induce emergence from sediment, and, thus increase predation risk. This is the first evidence that a combination of warming and deoxygenation stressors should reduce population survival of clams much more so than changes in a single stressor.     

Changes in embryonic development and hatching in Chionoecetes opilio (snow crab) with variation in incubation temperature

Water temperature affects the distribution, movement, and reproductive potential of female snow crab, Chionoecetes opilio. Ovigerous females of C. opilio from the eastern Bering Sea were held at five temperatures (-1, 0, 1, 3, and 6 degrees C) in the laboratory while their embryos developed from gastrula to hatching. The duration of incubation increased by 105 d (30%) with decreasing temperature; however, a switch to a 2-year duration of embryo incubation was not observed. For females held at 6, 3, and 1 degrees C, their embryos underwent a short period of diapause late in development; no diapause was observed for embryos of females held at 0 or -1 degrees C. Successful extrusion of a subsequent clutch and hatch timing comparable with that observed in the eastern Bering Sea indicated that temperatures of 0 to 3 degrees C may be optimal for multiparous female reproduction. We demonstrated that a switch from 1-year to 2-year reproduction cannot be triggered by changing the thermal regime after several months of embryonic development. The timing of female movement from colder to warmer waters may be important for maintaining population reproductive potential during the recent phase of warming and contraction of cold-water biomes in the Bering Sea.     

Temperature-related heart rate in water and air and a comparison to other temperature-related measures of performance in the fiddler crab Leptuca pugilator (Bosc 1802)

Performance in poikilotherms is known to be sensitive to temperature, often with a low-sloping increase with temperature to a peak, and a steep decline with increasing temperature past the peak. We complemented past measures of performance by measuring heartbeat rates of the fiddler crab Leptuca pugilator in water and in air as a function of a range of temperatures previously shown to affect other measures of performance. In water over a range of 20–50 °C, heartbeat increased steadily to a peak at 40 °C and then steeply declined to near zero at 50 °C. In air, heartbeat also increased, but to a peak at 35 °C and then with a gentler decline than was found in water. Part of this different response may be due to evaporative water loss, which reduced body temperature in air, and therefore thermal stress, relative to body temperature when crabs were immersed in water. Increased availability of oxygen from air, according to the oxygen and capacity-limited thermal tolerance hypothesis, likely increased aerobic scope past the thermal peak, relative to within water, where oxygen delivery at higher temperatures may have been curtailed.We compared the heart rate performance relations to two previous measures of performance – endurance on a treadmill and sprint speed, both done in air. The peak performance temperature increased in the order: treadmill endurance time, sprint speed, heart rate in air, and heart rate in water, which demonstrates that different performance measures give different perspectives on the relation of thermal tolerance and fitness to temperature. Endurance may therefore be the limiting upper thermal stress factor in male fiddler crabs, when on hot sand flats. Temperature preference, found to be for temperatures <30 °C in air, could be a bet-hedging evolutionary strategy to avoid aerobic scope affecting endurance.     

Effects of microwave exposure and temperature on survival of mice infected with Streptococcus pneumoniae

Female CD-1 mice were injected with an LD₅₀ dose of Streptococcus pneumoniae and then exposed to 2.45 GHz (CW) microwave radiation at an incident power density of 10 mW/cm² (SAR = 6.8 W/kg), 4 h/d for 5 d at ambient temperatures of 19 °C, 22 °C, 25 °C, 28 °C, 31 °C, 34 °C, 37 °C and 40 °C. Four groups of 25 animals were exposed at each temperature with an equal number of animals concurrently sham-exposed. Survival was observed for a 10-d period after infection. Survival of the sham-exposed animals increased as ambient temperature increased from 19 °C–34 °C. At ambient temperatures at or above 37 °C the heat induced in the body exceeded the thermoregulatory capacity of the animals and deaths from hyperthermia occurred. Survival of the microwave-exposed animals was significantly greater than the shams (～20%) at each ambient temperature below 34 °C. Based on an analysis of the data it appears that the hyperthermia induced by microwave exposure may be more effective in increasing survival in infected mice than hyperthermia produced by conventional methods (ie, high ambient temperature). Microwave radiation may be beneficial to infected animals at low and moderate ambient temperatures, but it is detrimental when combined with high ambient temperatures.