Sluggish Fish Research Articles

Cold winter fish slow down naturally rather than by depressing metabolism

We are all familiar with the archetypal grizzly bear, hedgehog and squirrel depressing their metabolism when snuggling down for their winter hibernation. But what about sluggish fish lurking at the bottom of icy pools? Are these so-called ‘cold-blooded’ (ectothermic) animals making an active choice to reduce their metabolism to conserve energy during winter, or are their metabolisms simply coming along for the ride as temperatures fall and they cool naturally? Cold critters run more slowly than warm ones. Unfortunately, it's difficult to tell the difference between the two scenarios. However, animals that actively suppress their metabolic rates tend to get more sluggish than animals that passively allow the chilliness to slow them down. Wondering whether cold-blooded fish are simply allowing their metabolic rates to remain in harmony with their surroundings or are actively depressing them, Connor Reeve, Lauren Rowsey and Ben Speers-Roesch from the University of New Brunswick, Canada, collected cunner, pumpkinseed sunfish, American eels and mummichogs to find out how the chilly fish weather winter conditions.First, the team wanted to find out when the fish switched from active lifestyles to sluggish winter existences as the temperature declined gradually to 1–2°C over a 14-day period. ‘The fish were held in their own plastic aquaria, which contained a pipe for shelter, and were video recorded continuously using an infrared-sensitive camera that can see in day and night’, says Reeve, who filmed the fish dining and pottering around their individual enclosures until it became too cold. Impressively, the mummichogs never became entirely still, even at the chilliest temperature of 1.1°C, although they gave up feeding by 3°C, and the sunfish also continued feeding and moving a little at temperatures below 7°C. However, the cunner all became inactive by 7–8°C and the eels gave up moving around by 3°C. But were the fishes actively suppressing their metabolic rates to a point where they were unable to remain active, or were their metabolic rates declining naturally as the water cooled?Next, the team recorded the fishes’ oxygen consumption rates, which provides an estimate of their metabolic rates, and filmed the animals’ antics as they cooled 3°C each day from their usual summer temperatures (14–17°C) to ∼2.5°C. Then, after allowing the fishes to adapt to the new chilly temperature for 4–6 weeks, the team rewarmed the fishes to their summer temperatures, as if experiencing a mini heatwave, while keeping track of the animals’ movements and oxygen consumptions the whole time. The team then calculated how much the fishes’ metabolic rates declined as they were chilled and rewarmed and discovered that the metabolic rates never changed by more than 3.5-fold for every 10°C temperature change, which is the minimum metabolic rate change experienced by animals that actively suppress metabolic rate to conserve energy. The metabolic rates of the cunner, pumpkinseed sunfish, American eels and mummichogs all tied in perfectly with temperature of their surroundings. They were simply going along with the metabolic flow, allowing themselves to be cooled naturally by their environment, rather than actively depressing their metabolism.However, the team suspects that instead of being completely dormant – like American eels and cunner, which shut down entirely at low temperatures – chilly pumpkinseed sunfish and mummichogs merely become lethargic. Reeve suggests that this form of winter lethargy ‘encompasses a larger intermediate scope of activity, relative to winter dormancy or winter activity’. In fact, the team reckons that most fish residing in temperate waters tend to the lethargic end of the spectrum – rather than full-blown dormancy – as many species remain active to some extent during long chilly winters.

Antioxidant defense system and oxidative status in Antarctic fishes: The sluggish rockcod Notothenia coriiceps versus the active marbled notothen Notothenia rossii

Adaptive responses of antioxidant defense systems (ADS) to changes in increased levels of activity are critical, especially in Antarctic fishes. The benthopelagic marbled notothen (Notothenia rossii) shows higher spontaneous activity than the benthonic and sluggish rockcod (N. coriiceps). Therefore, we hypothesize that species-related responses of ADS would occur to counteract different rates of reactive oxygen species formation in these two Antarctic fish. Here we evaluated ADS and oxidative damage in tissues (brain, gills, liver and white muscle) of the two Antarctic fish. Despite no significant differences in lipid and protein oxidative damage were observed, we actually found species- and tissue-specific differences in ADS. Gill metallothionein-like proteins (MTLP) and liver reduced glutathione (GSH) concentrations were higher in N. coriiceps than in N. rossii. Brain and gill antioxidant capacity against peroxyl radicals (ACAP); gill enzyme [glutamate-cysteine ligase (GSL), superoxide dismutase (SOD) and catalase (CAT)] activity; liver GCL and SOD activity; and white muscle CAT activity were higher in N. rossii than in N. coriiceps. Therefore, the more active fish (N. rossii) maintains higher activities of enzymes involved in superoxide ions (O2.-) detoxification and GSH production in peripheral tissues (gills, liver and white muscle). This allows the more active fish (N. rossii) to keep levels of lipid and protein oxidative damage similar to those observed in the sluggish fish (N. coriiceps). It is worth noting that the more active fish also shows a higher brain antioxidant capacity, which could involve other non-enzymatic antioxidants like vitamins C and E. In contrast, N. coriiceps shows lower consumption of non-enzymatic antioxidants in peripheral tissues than N. coriiceps. As hypothesized, our results indicate that differences in ADS profiles between fish species are likely related to their habits and metabolic rates. This would imply in different fish abilities to deal with oxidative stress associated with increasing seawater temperature.

The energy cost of embryonic development in fishes and amphibians, with emphasis on new data from the Australian lungfish, Neoceratodus forsteri

The rate of oxygen consumption throughout embryonic development is used to indirectly determine the 'cost' of development, which includes both differentiation and growth. This cost is affected by temperature and the duration of incubation in anamniote fish and amphibian embryos. The influences of temperature on embryonic development rate, respiration rate and energetics were investigated in the Australian lungfish, Neoceratodus forsteri, and compared with published data. Developmental stage and oxygen consumption rate were measured until hatching, upon which wet and dry gut-free masses were determined. A measure of the cost of development, the total oxygen required to produce 1 mg of embryonic dry tissue, increased as temperature decreased. The relationship between the oxygen cost of development (C, ml mg(-1)) and dry hatchling mass (M, mg) in fishes and amphibians is described by C = 0.30 M(0.22 0.13 (95% CI)), r (2) = 0.52. The scaling exponent indicates that the cost of embryonic development increases disproportionally with increasing hatchling mass. At 15 and 20°C, N. forsteri cost of development is significantly lower than the regression mean for all species, and at 25°C is lower than the allometrically scaled data set. Unexpectedly, incubation of N. forsteri is long, despite natural development under relatively warm conditions, and may be related to a large genome size. The low cost of development may be associated with construction of a rather sluggish fish with a low capacity for aerobic metabolism. The metabolic rate is lower in N. forsteri hatchlings than in any other fishes or amphibians at the same temperature, which matches the extremely low aerobic metabolic scope of the juveniles.

Stereological estimation of surface area and barrier thickness of fish gills in vertical sections

Previous morphometric methods for estimation of the volume of components, surface area and thickness of the diffusion barrier in fish gills have taken advantage of the highly ordered structure of these organs for sampling and surface area estimations, whereas the thickness of the diffusion barrier has been measured orthogonally on perpendicularly sectioned material at subjectively selected sites. Although intuitively logical, these procedures do not have a demonstrated mathematical basis, do not involve random sampling and measurement techniques, and are not applicable to the gills of all fish. The present stereological methods apply the principles of surface area estimation in vertical uniform random sections to the gills of the Brazilian teleost Arapaima gigas. The tissue was taken from the entire gill apparatus of the right-hand or left-hand side (selected at random) of the fish by systematic random sampling and embedded in glycol methacrylate for light microscopy. Arches from the other side were embedded in Epoxy resin. Reference volume was estimated by the Cavalieri method in the same vertical sections that were used for surface density and volume density measurements. The harmonic mean barrier thickness of the water-blood diffusion barrier was calculated from measurements taken along randomly selected orientation lines that were sine-weighted relative to the vertical axis. The values thus obtained for the anatomical diffusion factor (surface area divided by barrier thickness) compare favourably with those obtained for other sluggish fish using existing methods.

Feeding habits of Bathydraco marri (Pisces, Notothenioidei, Bathydraconidae) from the Ross Sea, Antarctica

In comparison with other bathydraconids, all species of the genus Bathydraco are poorly known from an ecological perspective. The diet of juvenile Bathydraco marri Norman, 1938 was studied for the first time in specimens collected in the southwestern Ross Sea during summer 1998. Fish were collected in a single otter trawl catch at 330–340 m depth. The stomach content analysis showed that this species fed exclusively on crustaceans. Overall, 20 prey taxa were identified to genus or species level. Mysids, amphipods and copepods were the most important prey in decreasing order of importance. Other prey, such as Euphausia superba, isopods and tanaids were eaten occasionally and in very small amounts. A multivariate analysis was applied to feeding data to assess ontogenetic or sex-related changes in diet. No difference was detected between sexes, whereas diet of small and large fish differed in some degree. An ontogenetic shift from small and pelagic crustaceans such as copepods to benthic–benthopelagic prey such as amphipods and mysids was observed. Relating present results with published data on physiological characteristics of B. marri, it was possible to infer their feeding behaviour and mode of life. Like other bathydraconids, this species appeared to be an inactive and sluggish fish, which relied on more or less motile benthic or epibenthic prey adopting a “sit and wait” feeding strategy. On the other hand, smaller fish seem to be more active, feeding also on pelagic prey such as copepods that can be seasonally abundant, thus reducing the intraspecific competition for food.

The Collected Poems of Kenneth Koch (review)

Reviewed by: The Collected Poems of Kenneth Koch Jason Koo The Collected Poems of Kenneth Koch By Kenneth KochAlfred A. Knopf, 2005, 761 pp., $40 It is time. Long overshadowed by his New York School affiliates John Ashbery and Frank O'Hara, and dismissed by critics for being too silly, Kenneth Koch should now get the attention he deserves with this beautiful edition of his collected poems published by Knopf three years after his death. The size of the book may come as a surprise to some—over seven hundred pages of poems—but for fifty years Koch was one of the most resourceful and energetic poets on the American scene, [End Page 161] pumping out big, inclusive poems that swallowed up the more small-minded works of his contemporaries. In the process Koch transformed himself from a minor poet who seemed too in love with his own high jinks to a major spirit of the age, one of those rare poets who excite you with a feeling of life almost the moment you step onto the page. Like his hero Vladimir Mayakovsky, Koch believed in a poetry of excitement. "Formerly I believed/books were made like this," Mayakovsky writes in "The Cloud in Trousers," "a poet came,/lightly opened his lips,/and the inspired fool burst into song." But the problem, he continues, is that "before they can launch a song,/poets must tramp for days with callused feet,/and the sluggish fish of the imagination/flounders softly in the slush of the heart." Koch's poems, like Mayakovsky's, often take as their subject the sorry state of poetry itself, over which the dull and overly serious reign supreme. "Why should we be organized to defend the kingdom/Of dullness?" he asks in his first signature poem, "Fresh Air." A grand master of the poetic smack-down, Koch lampoons the "young poets trembling in universities . . . bathing the library steps with their spit" (whom he offs via "the Strangler"), but also supposed untouchables: "Yeats of the baleful influence, Auden of the baleful influence, Eliot of the baleful influence . . ." In "The Art of Poetry," the central long poem of his career, he dishes it out to Wordsworth and Whitman as well: [Wordsworth] was really terrible after he wrote the "Ode: Intimations of Immortality from Recollections of Early Childhood," for the most part, Or so it seems to me. Walt Whitman's "corrections," too, of Leaves of Grass, And especially "Song of Myself," are almost always terrible. Koch is easily the funniest poet in the language. And his humor should not be regarded merely as a childish indulgence, a distraction from the real purpose of the art; it is a supremely liberating force, akin to the power of metaphor. Koch's humor, in other words, does not just amuse; it transforms. At any moment while reading a Koch poem an irrepressible smile can break out on your face, regardless of your mood. Take these two moments from "Some General Instructions" and "Straits": [End Page 162] When Pleasure is mild, you should enjoy it, andWhen it is violent, permit it, as far as You can, to enjoy you.El Greco lived in Seville but wasn't a SpaniardBut a Greek. As was the case with Christ, his name designated what,not who, he was. This brand of humor, like the stand-up of Mitch Hedberg, jolts you into life. Suddenly the world seems full of charm and wonder again. Single lines are often sublime in their silliness; they make you shake your head at the wonder of a man who thinks like this: O Labrador, you are the sexual Pennsylvania of our times! ["The Pleasures of Peace"] "Hit My Tits" could be a motto on the sailboat of your happiness. ["The Art of Love"] Koch can be too silly, and a great many poems in this book are throwaways, tedious in their excitability. Koch probably used more exclamation points than any writer in history, and when the writing is not inspired, it can seem like he's trying to rev a bad poem into a great one simply by using more excited punctuation. But when Koch is on, few poets...

Baseline respiration and spontaneous activity of sluggish marine tropical fish of the family Scorpaenidae

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 219:229-239 (2001) - doi:10.3354/meps219229 Baseline respiration and spontaneous activity of sluggish marine tropical fish of the family Scorpaenidae Christopher Zimmermann1,2,*, Andreas Kunzmann1,3 1Institut für Polarökologie der Universität Kiel, Wischhofstr. 1-3, Geb. 12, 24148 Kiel, Germany 2Institut für Seefischerei, Bundesforschungsanstalt für Fischerei, Palmaille 9, 22767 Hamburg, Germany 3Zentrum für Marine Tropenökologie, Universität Bremen, Fahrenheitstr. 6, 28359 Bremen, Germany *E-mail: czimmermann@ipoe.uni-kiel.de ABSTRACT: Baseline respiration and spontaneous activity were determined simultaneously for 6 specimens of tropical scorpionfishes, belonging to 2 different genera: Scorpaenopsis oxycephalus and S. diabolus (false stonefish) and Parascorpaena sp. and P. aurita. The experiments were conducted in an intermittent-flow respirometer at 24°C, at ambient light regime (12 h dark: 12 h light) and salinity (S = 32). Permanent measurements of fish activity by an infrared video system (number of movements) and oxygen consumption were coupled allowing the calculation of a standard oxygen consumption (SOC) rate. The experimental set-up allowed quantification of spontaneous activity. Relative SOC values varied between 32.3 mg O2 h-1 kg-1 wet mass (wm) for a large S. oxycephalus (82 g WM) and 68.9 mg O2 h-1 kg-1 WM for the smallest investigated specimen, a P. aurita (16 g WM). The latter also showed the highest spontaneous activity rate (mean 98 movements h-1; max.: 870 h-1), while the values for the most sluggish individual did not exceed 24.6 h-1 (mean) and 480 h-1 (max.), respectively. Absolute SOC for a standard mass of 50 g was calculated to be 2.0 mg O2 h-1, using a wet mass versus oxygen consumption relationship of SOC (mg O2 h-1) = 0.26 x WM(g)0.527. The tropical scorpionfish investigated are some of the most sluggish fish found on coral reefs, with activity levels (means and variance) similar to that of boreal or polar scorpaenids (e.g. sculpins). In this respect, there was no indication for any specific adaptation to temperature. Baseline oxygen consumption values of the fish in this study were the lowest recorded for marine tropical species, and a first rough comparison of the resting metabolism of scorpaenid fish over a wide range of environmental temperatures might indicate a reduced thermal sensitivity of the tropical fish investigated. KEY WORDS: Respiration · Standard oxygen consumption · Spontaneous activity · Coral reefs · Scorpionfishes · Scorpaenidae Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 219. Online publication date: September 10, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

On the respiration of Torpedo marmorata.

1. The oxygen consumption of resting Torpedo marmorata was measured using three different methods. The results indicate that this species has a much lower oxygen consumption than other elasmobranchs of comparable size. 2. The gills are ventilated by a mechanism similar to that of other rays, but a relatively small spiracular opening seems to be associated with a more important role of the oro-branchial pump. During hypoxia there is a marked increase in both frequency and amplitude of the ventilatory movements. 3. The frequency of the heart beat is low and shows little change during hypoxia, except under extreme conditions when bradycardia occurs. 4. In some individuals, coupling between cardiac and ventilatory pumps is relatively low but seems to increase at lower ventilatory frequencies and when the ratio between the ventilatory and cardiac frequencies is a whole number. 5. Extreme hypoxia can be withstood for many hours but eventually the ventilatory rhythm ceases; it does not recommence immediately following a rise in ambient oxygen tension. 6. The blood has a low oxygen-carrying capacity and a high affinity. 7. The surface area of the gills is smaller than that of other species that have been investigated, but the quantity of oxygen transferred/unit surface area is similar to that known for other species. 8. It is concluded that Torpedo is a sluggish fish adapted to conditions of low oxygen, but the conditions under which this occurs remain to be determined.

DIMENSIONS AND ULTRASTRUCTURE OF TOADFISH GILLS

1. This analysis of the measurement from the gills of about 60 toadfish using log/log transformation has shown that the gill area and its constituent parts increases with body weight as follows:Total area (mm2) = 560.7 W0.79 Total filament length(mm) = 302.1 W0.485 Secondary lamellae/mm on one side of filament = 15.99 W-0.075 Average bilateral area of a secondary lamella (mm2) = 0.06 W0.3722. A comparison with the corresponding data for other fish, particularly tunas, shows differences in the values of these relationships and confirms the general conclusion that the gills of more sluggish fish have a smaller number of larger secondary lamellae and relatively wider spaces through which the water flows.3. An electron microscope study of the toadfish secondary lamella has shown the same basic structure as in other teleost fish but the collagen layer of the basement membrane is especially thick. Also noticeable are distinct lymphoid spaces between the two epithelial layers and the presence of stages in the de...

The dimensions of fish gills in relation to their function.

ABSTRACTMeasurements have been made of the gill areas of fourteen species of British fish, all marine except for the tench and trout. In addition the gill area of the Antarctic icefish, Chaenocephalus (lacking haemoglobin) has been measured. The different parameters of the gill sieve have been considered quantitatively in relation to the size of the gill area, resistance to the passage of water, and the diffusion conditions at the gills. From calculations of the expected flow through a sieve of the measured dimensions it has been concluded that a sufficient volume would pass in the inter-lamellar spaces despite their fine dimensions. Differences in the nature of the sieve relative to the theoretical one and changes during the respiratory cycle account for the ventilation volumes measured being less than those calculated. The theoretical analysis of the operation of the gill sieve are discussed in relation to measurements of Gray (1954) and to the developmental studies of Price (1931). It is concluded that more active fish not only have larger gill areas but that the conditions for gaseous exchange are better than for more sluggish forms and that the area is increased in such a way as to keep the resistance to flow to a low value. This is mainly achieved by having an increased total filament length and a large number of secondary folds. More sluggish fish have more widely spaced and higher lamellae and their total filament length is reduced. The resistance to flow relative to the area is less in these forms than in the more active species. Consideration is given to the different pathways along which water can infiltrate past the respiratory epithelium and analogies are drawn with the alveolar air, and the physiological and anatomical dead-spaces of the mammalian lung.

A COMPARATIVE STUDY OF THE RESPIRATORY METABOLISM OF EXCISED BRAIN TISSUE OF MARINE TELEOSTS

1. The oxygen consumption of brain tissue of 17 species of marine teleost fishes was determined at 30° C.2. A positive correlation exists between rate of oxygen consumption and activity of fishes. The more active fishes, like the menhaden, had a higher Qo2 then the sluggish fishes, such as the toadfish.3. In general, when comparing results of this paper with various physiological indices of activity, a positive relationship was noted.4. Qo2 of brain tissue of the pinfish and the toadfish were independent of body weight and body length.

Notes From the Plymouth Aquarium. II

As known from ancient times, Electric Rays (Torpedo) have the power of giving severe numbing shocks, and it has repeatedly been stated that this power, which is electrical, is used both as a means of protection and for paralysing prey. That the shock is used in the capture of prey seems never to have been definitely proved. Indeed Roule (1935, p. 161) expresses the opinion that the electric shock is not used for securing food and even doubts that it is normally and effectively used as a means of defence. There appears to be no detailed account of the manner in which Torpedo feeds, but the ninth edition (1925) of the Guide to the Aquarium of the Zoological Station at Naples mentions (p. 106) that the Electric Ray rises from the mud to throw itself against approaching mullet (Mugil), and that the mullet, overcome by fright and electric shock, fall to the ground to be eaten. This very short and incomplete account was not seen until after the following paragraphs had been written.Both Torpedo nobiliana Bonaparte and T. torpedo L. occur from time to time off Plymouth, the former being by far the commoner, and both have been kept in our aquarium tanks. They are sluggish fishes, spending most of the time lying still on the bottom, occasionally swimming for short spells. They swim by sculling with the tail, which has a large caudal and two dorsal fins. This mode of swimming differs strikingly from that of normal rays, which undulate the pectoral fins and trail their tails' it resembles the swimming movements of Rhina squatina (L.), another fish with a sluggish disposition and, as noted below, some other resemblances to Torpedo.

THE AUTOLYSIS OF MUSCLE OF HIGHLY ACTIVE AND LESS ACTIVE FISH

1. All fish muscles examined show the typical pattern of catheptic activity characteristic of such mammalian tissues as liver, kidney, spleen and muscle.2. Muscles of the relatively sluggish fish such as carp, gar, dogfish and cod autolyze slowly and to a relatively small extent in the ten-day period of the experiments.3. Muscle from the game fish mackerel, albacore, bonita and sword-fish autolyze much more rapidly and completely in the same time, and under the same conditions.4. A correlation appears to exist between the normal functional activity of the muscles and the speed and extent to which they digest. This represents we believe a mechanism for maintenance of activity through mobilization of tissue proteins during periods of food scarcity.5. The data suggest that muscle proteins of the active species are more readily fragmented by the enzymes present than are the proteins of less active species.

BLOOD SUGAR AND ACTIVITY IN FISHES WITH NOTES ON THE ACTION OF INSULIN

1. Correlations between the blood sugar, hemoglobin, body-form, activity and habits of fifteen species of marine teleosts are pointed out.2. The fishes that show the greatest activity, those that feed at the surface or are aggressively predaceous, have the highest blood sugar concentration. The sluggish bottom feeders have low sugar content in the blood.3. Insulin shock may be easily produced in active species of fishes. In sluggish forms no external evidence of the action of insulin could be detected.4. The blood sugar of fishes is reduced by the action of insulin. Less time is required for reduction of sugar content to take place in the active fishes than in the sluggish forms, due probably to differences in the metabolic rate of the different species. In the sluggish forms the sugar content may be reduced without convulsions or shock being apparent.5. The normal sugar of some of the sluggish fishes is often lower than the insulin-reduced sugar of the more active fishes.