Studies on the transport of sugars in the holothurian Holothuria scabra

Experiments using ¹⁴C sugars were carried out on the holothurian Holothuria scabra Jäger, in order to assess the role of its perivisceral fluid in the translocation and transportation of dissolved organic materials. The results obtained indicate that the perivisceral fluid plays a significant part. Rates of ¹⁴C glucose, fructose and sucrose uptake were followed in major tissues such as the alimentary canal, haemal system, respiratory tree and body wall. The monosaccharides are absorbed more intensively by digestive and haemal systems, the disaccharide by respiratory tree and body wall. It is, therefore, presumed that tissues in H. scabra selectively absorb sugars depending on their metabolic activity.     

Interception and dispersal of artificial food falls by scavenging fishes in the abyssal Northeast Atlantic: early-season observations prior to annual deposition of phytodetritus

The hypothesis that the behaviour of deep-sea scavenging fishes is influenced by seasonal input of organic matter from the ocean surface was investigated by observing responses to baits placed on the sea floor at 4800 m depth in the NE Atlantic (48°50′N; 16°30′W) during spring (April 1994). Data from the present study are compared with those from previous studies of the same location made in summer 1989. The first fishes to arrive at baits were the grenadier Coryphaenoides (Nematonurus) armatus and the eel Histiobranchus bathybius, after delays of 28 and 29 min, respectively; these results are not significantly different from those of summer 1989. Similarly, other indices of activity (staying time and swimming speed) showed no evidence of differences between years/seasons. However, the rate of radial dispersal of bait (0.009 m s⁻¹) by C. (N.) armatus was much slower than in all previous studies. A change in the size distribution of C. (N.) armatus to smaller individuals in spring 1994 was also evident. It is suggested that the fish on the abyssal plain may not comprise a steady-state population and that major episodic or seasonal migrations may occur. Received: 18 October 1996 / Accepted: 20 December 1996     

Gill and intestinal Na+-K+ ATPase activity, and estimated maximal osmoregulatory costs, in three high-energy-demand teleosts: yellowfin tuna (Thunnus albacares), skipjack tuna (Katsuwonus pelamis), and dolphin fish (Coryphaena hippurus)

We hypothesize that the morpho-physiological adaptations that permit tunas to achieve maximum metabolic rates (MMR) that are more than double those of other active fishes should result in high water and ion flux rates across the gills and concomitant high osmoregulatory costs. The high standard metabolic rates (SMR) of tunas and dolphin fish may, therefore, be due to the elevated rates of energy expenditure for osmoregulation (i.e. teleosts capable of achieving exceptionally high MMR necessarily have SMR). Previous investigators have suggested a link between activity patterns and osmoregulatory costs based on Na⁺-K⁺ ATPase activity in the gills of active epipelagic and sluggish deep-sea fishes. Based on these observations, we conclude that high-energy-demand fishes (i.e. tunas and dolphin fish) should have exceptionally elevated gill and intestinal Na⁺-K⁺ ATPase activity reflecting their elevated rates of salt and water transfer. To test this idea and estimate osmoregulatory costs, we measured Na⁺-K⁺ ATPase activity (V _max) in homogenates of frozen samples taken from the gills and intestines of skipjack and yellowfin tunas, and the gills of dolphin fish. As a check of our procedures, we made similar measurements using tissues from hybrid red tilapia (Oreochromis mossambicus ×O. niloticus). Contrary to our supposition, we found no difference in Na⁺-K⁺ ATPase activity per unit mass of gill or intestine in these four species. We estimate the cost of osmoregulation to be at most 9% and 13% of the SMR in skipjack tuna and yellowfin tuna, respectively. Our results, therefore, do not support either of our original suppositions, and the cause(s) underlying the high SMR of tunas and dolphin fish remain unexplained. Received: 7 September 2000 / Accepted: 4 December 2000     

Deep-sea bottom-living fishes at two repeat stations at 2 200 and 2 900 m in the Rockall Trough,northeastern Atlantic Ocean

Repeated sampling of deep-sea bottom-living fishes was conducted at two stations in the Rockall Trough at depths of 2 200 and 2 900 m. The 2 200 m station (M) was sampled 16 times by an Agassiz trawl between April 1978 and April 1985 and yielded 473 fish belonging to 17 species. The 2 900 m permanent station (PS) yielded 781 fish belonging to 11 species from 9 Agassiz trawls, 2 small box otter trawls, 4 semi-balloon otter trawls and 7 epibenthic sledges between March 1975 and April 1985. Macrourid fishes were numerically dominant at both stations with Coryphaenoides guentheri and Coryphaenoides (Nematonurus) armatus being the most abundant species at M and PS, respectively. In terms of biomass the morid, Antimora rostrata, was dominant at M but C. (N.) armatus was dominant at PS. The only species that showed clear evidence of a seasonal reproductive cycle was C. guentheri. Many species showed no indication of reproducing in the Rockall Trough. The diets of almost all the species are described and considered in relation to the food resources exploited. Investigations on the pelagic and benthic invertebrate faunas at these stations should reveal the extent to which the bottom-living fishes exploit the available resources.     

饵料加标研究二甲苯麝香在鱼体内的蓄积和清除能力

二甲苯麝香(musk xylene,MX)是一种人造麝香,具有强烈的麝香气,可用作化妆品香精和皂用香精等的定香剂。由于其持续不断地输入环境,它们在水、土壤、大气中的浓度逐渐升高,并且在动物和人体组织中产生了蓄积,其蓄积效应相当于有机氯农药(organochlorine pesticides,OCPs)等持久性有机污染物,因而研究MX在鱼体内的蓄积特征是十分必要的。本文用含浓度为50 mg·kg-1和100 mg·kg-1的MX的饵料投喂斑马鱼(Danio rerio)和稀有鮈鲫(Gobiocypris rarus)14 d,继而进入为期28 d的清除实验。通过快速溶剂萃取(accelerated solvent extraction,ASE)、凝胶渗透色谱(gel permeation chromatography,GPC)、气相色谱-质谱联用法(gas chromatography-mass spectrometry,GC-MS)测定斑马鱼和稀有鮈鲫体内MX的浓度,继而评估鱼对MX的清除能力。结果表明,饵料中MX浓度越高,鱼体内MX的蓄积水平越高,100 mg·kg-1浓度组的蓄积水平为50 mg·kg-1浓度组的蓄积水平的2~3倍。在整个试验阶段的不同时间点分析鱼的体重和脂肪与鱼体内MX浓度的关系,数据显示,MX在鱼体内的蓄积水平与鱼的体重存在正线性关系,而与鱼体内脂肪含量的关系还有待进一步研究。经28 d的清除,鱼体内的MX残留量接近于零,说明斑马鱼和稀有鮈鲫对MX的清除能力较强。     

Fluids and jellies of the acusticolateralis system in relation to body fluids in Coryphaenoides rupestris and other fishes

The marine deep-water fish Coryphaenoides rupestris has a lymph-like fluid in its large cranial lateral-line canals. A similar canal endolymph is also found in a few other fishes possessing closed lateral-line canals. We have analysed, chemically, the canal endolymph from 3 species of teleosts. In C. rupestris, the ionic composition resembles that of blood plasma, but the content of potassium is slightly lower. In Lota lota, the canal endolymph has a high potassium concentration, as does the inner-ear endolymph. In Glyptocephalus cynoglossus, the ionic composition of the canal endolymph resembles sea water. In all species, the concentrations of glucose and protein are much lower than in the blood plasma. Analyses were further made on endolymph and perilymph of the inner ear, on jelly-like material from the acusticolateralis system, and on body fluids from a small number of fish species, even elasmobranchs and a holocephalan. The water phase of the cupulae of the lateral-line system of C. rupestris had an ionic composition similar to that of the endolymph surrounding the cupulae. High potassium and low values for glucose and protein were found in the inner-ear endolymph of all species investigated. No carbonic anhydrase activity was found in the lateral-line system of C. rupestris, whereas a low activity of this enzyme was found in the inner ear of Gadus morrhua. The investigation shows that the composition of the fluids in contact with the mechano-receptors of the lateral-line system differs between different species of fishes. A few observations were made on the structural organization of the cranial lateral-line system in C. rupestris.     

Photographic and acoustic tracking observations of the behaviour of the grenadier Coryphaenoides (Nematonurus) armatus the eel Synaphobranchus bathybius,and other abyssal demersal fish in the North Atlantic Ocean

Using an autonomous free-fall vehicle (AU-DOS), observations were made of demersal fish attracted to baits and baited acoustic transmitters at two stations in the North Atlantic Ocean. A comparison was made between Station PAP (48°50N; 16°30W), 4800 m deep on the Porcupine Abyssal Plain which is relatively eutrophic, and Station MAP (31°N; 20°W), 4900 m deep on the Madeira Abyssal Plain, which is oligotrophic. Experiments were conducted during summer, in 1989 and 1990. Four species of fish were observed at Station MAP, the grenadier, Coryphaenoides (Nematonurus) armatus, the eel, Synaphobranchus bathybius, and the ophidiids Spectrunculus grandis, and Barathrites sp. At Station PAP, C. (N.) armatus and H. (S.) bathybius were attracted to bait on all deployments and only two other individuals of different species, probably ophidiids, were seen. The mean first grenadier arrival time was 30 and 138 min at Stations PAP and MAP, respectively. Mean first eel arrival time was 29 and 151 min at Stations PAP and MAP, respectively. Estimated population densities of fish were 167 grenadiers km^-2 and 180 synaphobranchid eels km^-2 at Station PAP and 8 grenadiers km^-2 and 7 eels km^-2 at Station MAP. Only the grenadier C. (N.) armatus definitely ingested transmitters, and this species dominated fish activity around the baits. Mean time of departure of grenadiers with transmitters in their stomachs across an acoustic horizon at 1000 m range was 371 and 488 min at Stations PAP and MAP, respectively. Grenadiers had a longer mean staying time at the food source at the more oligotrophic Station MAP (364 min) than at Station PAP (141 min). This corresponds with predictions of optimal foraging theory.     

Gas–liquid chromatography for fenvalerate residue analysis: alterations in the ionic concentration and associated adinosine triphosphatases in fish,Cirrhinus mrigala (hamilton)

In the present study, an attempt has been made to quantify the fenvalerate accumulated in different tissues (gill, muscle and liver) and observe changes involved in the levels of sodium, potassium and calcium ions and Na⁺–K⁺, Mg²⁺ and Ca²⁺ adenosine triphosphatase (ATPase) activities in the freshwater fish, Cirrhinus mrigala on short-term and long-term exposure to the median lethal and sublethal concentration of fenvalerate. Residue analysis using gas–liquid chromatography (GLC) technique revealed that fenvalerate accumulated in highest quantity in gill followed by liver and muscle under median lethal concentration (6?µg?L^?1). Whereas in sublethal concentration (0.6?µg?L^?1), muscle accumulated highest quantity followed by gill and liver, which might be due to the fact that fenvalerate is highly lyphophilic. The ion concentration and ATPase activity were found effected in fish exposed to lethal and sublethal concentrations of fenvalerate. Concentration of Na⁺, K⁺ and Ca²⁺ ions decreased in gill, muscle and liver on being exposed to median lethal concentration to a significant level. Whereas the changes were not highly pronounced at sub lethal level indicating low concentration of fenvalerate and its non-toxic effect at chronic exposure. Na⁺–K⁺, Mg²⁺ and Ca²⁺ ATPases activity were also found decreased in correspondence to the ionic change under median lethal and sub lethal concentrations in target tissues. This might have lead to behavioural changes and create wide-spread disturbance in the normal physiology, ultimately causing the death of the fish. The results suggest that in biomonitoring programmes, ions and associated ATPases can be a good diagnostic tool for fenvalerate toxicity.     

Morphology and kinematics of prey capture in the syngnathid fishes Hippocampus erectus and Syngnathus floridae

The mechanism of prey capture in two syngnathid fishes, the lined seahorse Hippocampus erectus (Perry) and the dusky pipefish Syngnathus floridae (Jordan and Gilbert), is described based on anatomical observations and high-speed video recordings (200 and 400 images s⁻¹) of feeding events by four seahorses and three pipefish. The fish were collected near Turkey Point, Florida, U.S.A., in January 1994 to March 1995. The dominant features of the morphology of these and many other syngnathiform fishes include extreme elongation of the suspensorium and neurocranium with a small mouth located at the anterior tip of the head. In the seahorse, a preparatory phase of prey capture consisted of slow ventral head flexion. This was followed by rapid elevation of the head and snout as the prey was drawn into the mouth by suction. Both H. erectus and S. floridae capture prey rapidly, with peak head excursions and mouth opening occurring within 5 to 7 ms of the onset of the strike. There was no upper jaw protrusion. In both species the time to recovery of the cranium and hyoid apparatus to resting positions was highly variable but took at least 500 ms. Manipulations of freshly dead specimens indicated a biomechanical linkage between head elevation and hyoid depression. However, the predictions of a previously proposed four-bar linkage model that couples hyoid depression to head elevation were not fully supported by kinematic data from one seahorse, suggesting that additional linkages act during the expansive phase of prey capture. These species exhibit the generalized kinematic pattern of prey capture in bony fishes, with head elevation, hyoid depression and mouth opening occurring almost simultaneously. The derived morphology results in a unique feeding behav‐ior, in which prey are captured during a sudden up-swing of the head, which brings the mouth to the prey. Suction is used to draw the prey into the buccal cavity. Received: 4 August 1996 / Accepted: 27 August 1996     

Effect of salinity fluctuation on the osmotic pressure and Na+, Ca2+ and Mg2+ ion concentrations in the hemolymph of bivalve molluscs

Specimens of Chlamys opercularis, Modiolus modiolus, Mytilus edulis, Crassostrea gigas, Scrobicularia plana and Mya arenaria were exposed to both gradual (sinusoidal) and abrupt (square-wave) salinity fluctuations and measurements made of osmotic, Na⁺, Mg²⁺ and Ca²⁺ concentrations in the hemolymph and where applicable in the mantle fluid. In both sinusoidal and square-wave regimes fluctuating between 100 and 50% seawater (100%=ca. 32 S), the hemolymph Na⁺, Mg²⁺, Ca²⁺ and osmotic concentrations followed the concentrations of the external medium in Chlamys opercularis. The hemolymph and mantle fluid osmotic Na⁺, Mg²⁺ and Ca²⁺ concentrations of Modiolus modiolus, Mytilus edulis, Crassostrea gigas and S. plana followed those of the external medium as long as the molluscs' shell valves remained open. There were no changes in the ionic or osmotic concentrations of the hemolymph or mantle fluid of any of these species during periods of shell-valve closure. The hemolymph osmotic, Na⁺ and Mg²⁺ concentrations of wedged-open Modiolus modiolus, Mytilus edulis, C. gigas and S. plana followed those of the external medium. Hemolymph Ca²⁺ concentrations showed a damped response in C. gigas and Mytilus edulis. The hemolymph osmotic, Na⁺, Ca²⁺ and Mg²⁺ concentrations of Mya arenaria fluctuated in a similar manner to the external medium, but were damped. Wedged-open Mytilus edulis exposed to fluctuating salinity and supplied with a constant supply of 10 mM Ca²⁺ showed greater changes in hemolymph ionic and osmotic concentrations than M. edulis exposed to the same salinity fluctuation without a constant Ca²⁺ supply. Chlamys opercularis and Modiolus modiolus survived in a 50% seawater minimum sinusoidal salinity fluctuation for 10 days; wedged-open M. modiolus survived only 3 days. Burrowing had no effect on the osmotic, Na⁺, Mg²⁺ or Ca²⁺ concentrations of the hemolymph of Mya arenaria or S. plana exposed to fluctuating salinities. All of the species studied were shown to be osmoconformers.     

Biomarkers as tools to assess the chronic toxicity of ammonia in the juvenile Mugil cephalus

With juvenile fish as the subject, the effects of low concentration ammonia on antioxidant system were studied using Mugil cephalus. Samples of gill and liver tissue were obtained from 0.35, 0.70, 1.5 and 3?mg/L ammonia groups at 0, 5, 10, 15 and 20 days of exposure, at which times the biomarkers were measured. Results showed that gill malondialdehyde (MDA) content exhibited an initial significant increase (p?≤?0.05) at unionised ammonia concentrations of 0.70, 1.5 and 3.0?mg/L on day 5, followed by subsequent declines, while liver MDA levels exhibited significant increases (p?≤?0.05) at unionised ammonia concentrations of 1.5?mg/L starting on day 10 and at 3.0?mg/L starting on day 5. With exposure to ammonia at different concentrations, Na⁺-K⁺-ATPase activity in liver and gill decreased over time. The Na⁺-K⁺-ATPase activity was negatively related to ammonia concentration from 0.70 to 3.0?mg/L. Overall, our results show that MDA and Na⁺-K⁺-ATPase, evaluated here as potential biomarkers of ammonia exposure, exhibited responses to sublethal concentrations of ammonia that were concentration dependent.     

Luminous bacteria of a monocentrid fish (Monocentris japonicus) and two anomalopid fishes (Photoblepharon palpebratus and Kryptophanaron alfredi): population sizes and growth within the light organs,and rates of release into the seawater

The light organs of monocentrid and anomalopid fishes consist of bacteria-filled tubular invaginations of the epidermis which are connected to the surrounding seawater by ducts. We used the release of bacteria from the light organs to estimate bacterial rates of growth in the light organs. For one monocentrid fish (4 specimens of Monocentris japonicus collected at Jogashima, Japan in 1980) and for two anomalopid fishes (2 specimens each of Photoblepharon palpebratus collected at Sebu, Phillipines in 1981 and Grand Comore Island in 1975 and Kryptophanaron alfredi collected at Parguera, Puerto Rico in 1982) we measured rates of release of bacteria into the surrounding seawater and the bacterial population sizes in the light organs; from this information we calculated doubling times of bacteria in the light organs. In addition, we determined the luminescence of bacteria after their release into the seawater. For M. japonicus, two specimens released 1.1 to 6×10⁶ and 2×10⁷ bacteria h^–1, respectively; the light organs contained about 1.5×10⁸ bacteria. For P. palpebratus, one specimen released 2.2×10⁸ bacteria h^–1; a second specimen had light organs containing 5.2×10⁹ bacteria. For K. alfredi, one specimen released 7×10⁷ bacteria h^–1 and had light organs containing 5.6×10⁸ bacteria; a second specimen released 3.6×10⁷ bacteria h^–1 and had light organs containing 7.3×10⁸ bacteria. Bacterial doubling times in the light organs of these three fishes were variable and ranged from 7.5 to 135 h in M. japonicus and 8 to 23 h in the anomalopids. Bacteria released from M. japonicus into the seawater remained viable, but bacteria from all of the fishes soon ceased to emit light.     

Die stickstoffhaltigen stoffwechselendprodukte und ihre exkretion bei Paracentrotus lividus

The perivisceral fluid of Paracentrotus lividus (Lamarck) contains, as main end-products of the nitrogenous metabolism, ammonia, urea, creatine, creatinine and traces of uric acid. In the organs analysed, the distribution and abundance of ammonia and urea fluctuate considerably. the intestine was found to have the highest NH₄ ⁺?N and the lowest urea-N contents. The axial organ contained the highest amount of urea-N and the lowest quantity of NH₄ ⁺?N; the perivisceral fluid, including the coelomocytes, contained intermediate amounts. The special relations to hemal system and coelothel, the presence of excretory material, and the analogous conditions to other invertebrates, suggest that the coelomocytes and parts of the intestine and axial organ are excretophoric and able to synthesize urea. From the known distribution of ammonia and urea in echinoid species, it is concluded that the ability to synthesize urea must have developed and improved in efficiency during echinoid evolution. P. lividus is predominantly ureotelic. It excretes approximately 91% of the nitrogenous wastes released into the surrounding sea water as urea-N, and only 9% as ammonia-N. Ammonia, and most of the urea, are excreted via the body surface — probably through respiratory surfaces; however, one third of the urea is excreted through the intestine, since urea excretion decreases by this amount when the anus is sealed artificially.     

Bioenergetics of fishes in a high-energy surf-zone

Energy budgets are proposed for four teleost and two elasmobranch species as well as for the main icthyofauna groups for a surf-zone ecosystem. The ecology of surf-zone fishes of eastern Cape beaches, Algoa Bay South Africa, is reviewed. Using the equationC=F+U+R _d +R _R +B, the following general energy budgets were derived for fishes: teleosts – 100=10+4+21+23+42; elasmobranchs – 100=11+2+16+24+48; whereC: food consumption;F: faeces;U: nonfaecal excretion;R _d : apparent specific dynamic action;R _R : routine metabolism;B: growth. These show that most of the energy consumed is used in metabolism (R _d +R _R ) and growth (B) whereas excretion (U) only accounts for a small portion. The energy budgets developed are within ranges recorded for other species. The main feeding groups of surf-zone icthyofauna are the southern mulletLiza richardsonii, the sandsharkRhinobatos annulatus, benthic feeders, zooplankton feeders, omnivorous and piscivorous fish with biomass values of 1000, 1000, 3000, 2400, 400 and 400 kJ m^–1, respectively; and annual consumption budgets of 22107, 13725, 65710, 65476, 9758 and 8517 kJ m^–1 yr^–1, respectively.L. richardsonii feeds mainly on surf diatoms, consuming 0.5% of total diatom production. Zooplankton production supplies 91%, and macrobenthic production 9%, of the energy needs of other non-piscivorous carnivorous fishes. Piscivorous fishes consume 30% of the available fish production. Nonfaecal-energy production (8229 kJ m^–1 yr^–1) is utilised by surf diatoms, and faecal-energy production (30 341 kJ m^–1 yr^–1), is returned to the detritus pool to be utilised by the microbial loop in surf-waters. Our current knowledge of surf-zone energetics indicates that fishes are important predators. This study confirms the concept that the ecosystem generates adequate food for the fish assemblage. Fishes recycle energy, as excretory products, via the detritus pool and surf-diatoms, while fishes moving across the outer boundary of the surf-zone export energy from the system. Data presented, therefore, also support the general concept of a self-sustaining beach/surf-zone ecosystem.Please address all correspondence and requests for reprints to Dr Du Preez at his present address: Research Unit for Fish Biology, Rand Afrikaans University, P.O. Box 524, Johannesburg 2000, Republic of South Africa     

Effects of sublethal concentrations of permethrin on bioaccumulation of cadmium in zebra cichlid (Cichlasoma nigrofasciatum)

The aim of this study was to evaluate the synergistic and antagonistic effects of permethrin on the bioaccumulation of cadmium in zebra cichlid (Cichlasoma nigrofasciatum). Zebra cichlid was exposed to various sublethal concentrations of permethrin combined with cadmium chloride for 15 days. Although at the lowest concentrations, permethrin (0.40 µg L^?1) decreased the bioconcentration potential of cadmium in fish, bioaccumulation of cadmium increased along with increasing concentrations of permethrin (0.80–1.20 µg L^?1). However, the magnitude of changes in the accumulation of cadmium in the fishes simultaneously exposed to 1.60 µg L^?1 permetrin and cadmium chloride was similar to the cadmium levels observed in fishes after exposure to the cadmium chloride alone. The results of this study suggest that the synergistic effects of permethrin on the bioaccumulation of cadmium highly depend on the concentrations of this pesticide in water.     

Determination of persistent organic pollutants in sediment and fish of the western coast of Alexandria,Egypt

Persistent organic pollutants (POPs) were recorded in sediment and fish samples collected from the western coast of Alexandria. Total hydrocarbons (aliphatic+PAHs ) in sediment ranged from 683.8 to 34670.1 ng g ^?1 with an average of 9286.9 ng g ^?1. The sum of C16–C34 of aliphatic fractions was<4000?ng g;^?1, indicating the presence of a fresh petroleum source. For all sediments, the anthracene/phenanthrene ratio was>0.1, suggesting the dominance of a pyrolytic source. Total aliphatics in different fish species ranged from 253 to 11?132 ng g;^?1, while total PAHs ranged from 3862 to 35?746 ng g;^?1 wet weight. Benzo[a]pyrene was the most dominant PAH fraction ranged from 1902.7 to 32 905.5 with an average of 9464.5?ng g;^?1 wet weight in all fish species. Concentrations of polychlorinated biphenyls (PCBs) ranged from 0.79 to 64.9?ng g;^?1 with an average 12.14?ng g;^?1 wet weight. The concentrations of organochlorines in fish species (Euthynnus alleferatus, Scomberomorus commerson, Sphyraena Sphyraena, Diplodus vulgaris, and Alepes djedaba) decreased following the order: PCBs>DDTs>HCHs>total cyclodienes. Concentrations of DDTs in fish tissues ranged from 4.89 to 36.37 ng g^?1 with an average of 16.4?ng g;^?1 wet weight. The concentrations of total HCHs ranged from 0.3 to 65.7?ng g;^?1 with an average of 16.35?ng g;^?1. The present study indicates: (1) fresh petroleum input where Pr/Ph>1; (2) PAHs in sediment<4000 ng g ^?1; (3) BaP concentration exceeded the permissible levels in Alepes djedaba species; (4) DDTs in sediment were below the effective range low level; (5) PCBs>effective range low and相似文献   

Sulfide tolerance and detoxification in shallow-water marine fishes

Hydrogen sulfide is a potent inhibitor of aerobic respiration. Sulfide is produced in sediments, and many species of fish live in association with the bottom. Tolerance tests, enzyme assays, and chromatography of sulfur compounds in thirteen species of shallow-water marine fishes (collected in San Diego, California, USA in 1987–1988) indicate adaptations to sulfide that vary with habitat and lifestyle. Tidal-marsh inhabitants, like Gillichthys mirabilis and Fundulus parvipinnis, have higher tolerance to sulfide (96 h LC₅₀ at 525 to 700 M) relative to outer-bay and open-coast inhabitants (surviving <12 h at much lower concentrations). The cytochrome c oxidase of all species shows high activity and susceptibility to sulfide poisoning, with 50% inhibition at 30 to 500 nM in various tissues. The two marsh species are able to survive at sulfide concentrations already inhibitory to their cytochrome c oxidase and fatal to other species. All species detoxify sulfide by oxidizing it to thiosulfate. All have sulfide-oxidizing activity in the blood, spleen, kidney, liver and gills, which correlates significantly with heme content. Thiosulfate appears in the tissues of sulfide-exposed fish and builds up to high concentrations (up to 2 mM) with stronger and longer exposure. Unexposed fish contain little or no thiosulfate. Sulfide is barely detectable in the tissues, even in high-sulfide exposure tests. We suggest that fish blood, in having high sulfide-oxidizing activity and no cytochrome c oxidase, can act as a short-term first line of defense against sulfide, and thus minimize the amount that reaches the vital organs. The results of this study indicate that sulfide is a significant environmental factor influencing the ecological distribution of marine fishes.     

Na+-K+-adenosine triphosphatase activities in gills of marine teleost fishes: Changes with depth,size and locomotory activity level

Activities of the primary enzyme responsible for monovalent ion regulation, Na⁺-K⁺-adenosine triphosphatase (Na⁺-K⁺-ATPase), were measured in gills of marine teleost fishes with different depths of occurrence (0 to 4800 m), body weights (a range of five orders of magnitude), and locomotory capacities. Specimens were collected off the coasts of California and Oregon in 1983–1989, and at the Galápagos Spreading Center and 13°N East Pacific Rise hydrothermal vent sites in 1987 and 1988, respectively. Except for two hydrothermal vent fishes, deep-sea species had much lower Na⁺-K⁺-ATPase activities g^–1 gill filament than shallow-living species, indicating that osmoregulatory costs, like total metabolic rate, are greatly reduced in most deep-living fishes. Within a species, the total branchial Na⁺-K⁺-ATPase activity per individual was dependent on size; the average allometric scaling exponent was 0.83. Using published values for oxygen consumption rates, and the total branchial Na⁺-K⁺-ATPase activities as an index of osmoregulatory costs, we estimated the maximal cost (as percent of ATP turnover) for osmoregulation in ten teleosts. Osmoregulatory costs averaged about 10% of total ATP turnover among these species, and maximal costs were no greater than about 20%. The percent costs of osmoregulation did not differ between shallow- and deep-living fishes. The reduced total ATP expenditure for osmoregulation in deep-living fishes is proposed to result from the sluggish locomotory habits of these fishes, not from selection for reduced osmotic coastper se. Thus, the reduced swimming abilities of these fishes lead to lower rates of water flow over the gills and less blood flow through the gills due to reduced demands for oxygen. Consequently, passive flux of water and ions through the gills is much lower than in more active fishes, and osmotic costs are thereby minimized. The relatively high activities of Na⁺-K⁺-ATPase in gills of the two hydrothermal vent fishes suggest that these fishes may be more active and have higher metabolic rates than other deep-sea fishes.     

Element levels in cultured and wild sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) from the Adriatic Sea and potential risk assessment

In this study, the role of aquaculture activity as a source of selected metals was analyzed. Significant differences in element content between cultured (Dicentrarchus labrax, Sparus aurata) and wild fishes as well as between fish muscle and their feed were detected. Higher concentrations of trace elements (i.e., As, Cu, Hg, Se) in wild fish tissues in comparison with cultured ones indicate additional sources of metals beside fish feed as natural and/or anthropogenic sources. Generally, mean Cd, Cu, Pb, Se, and Zn concentrations in cultured (0.016, 1.79, 0.14, 0.87, and 34.32 μg/g, respectively) and wild (0.011, 1.97, 0.10, 1.78, and 23,54 μg/g, respectively) fish samples were below the permissible levels, while mean As (2.57 μg/g in cultured, 4.77 μg/g in wild) and Cr (5.25 μg/g in cultured, 2.92 μg/g in wild) values exceeded those limits. Hg values were lower in cultured (0.17 μg/g) and higher in wild (1.04 μg/g) fish specimens. The highest elemental concentrations were observed in almost all fish samples from Kor?ula sampling site. The smallest cultured sea basses showed As (4.01 μg/g), Cr (49.10 μg/g), Pb (0.65 μg/g), and Zn (136 μg/g) concentrations above the recommended limits; however, values decreased as fish size increased. Therefore, the majority of metal concentrations in commercial fishes showed no problems for human consumption. Also calculated Se:Hg molar ratios (all >1) and selenium health benefit values (Se-HBVs) (all positive) showed that consumption of all observed fishes in human nutrition is not risk.     

ATP content and adenylate energy charge of the mussel Mytilus edulis during the annual reproductive cycle in Lindåspollene,Western Norway

The oxygen consumption rates ( VO₂) of 6 specimens (6 to 13 kg) of the albacore tuna Thunnus alalunga were measured at sea, using specimens collected 300 km west of San Diego, California (USA) during July and August, 1981. Fish were tested in a closed continuous-flow respirometer, where they swam at about 1.3 body lengths s^-1 velocity in 15° to 19°C water. The albacore tuna is a temperate pelagic species experiencing water temperatures from about 10° to 20°C and attaining a maximum weight of 45 kg. The VO₂ ranged from 1 249 to 3 336 ml h^-1 (the mean VO₂ for the 6 fish was 2 228 ml h^-1); such values approach those of mammals of a similar size and are 3 to 4 times those of most active fishes (e.g. sockeye salmon). Among fishes, the only higher VO₂ values yet recorded were for the skipjack tuna Katsuwonus pelamis, a tropical species. The remarkably high metabolic rates of tunas are presumably correlated with their continuous swimming activity and the maintenance of endothermy. The exponent relating VO₂ to body weight (1.18), although large, is not statistically different from the exponents for most other active vertebrates.