Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FISHES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67Linked to original sources
PubMed1999

Consumption of freshwater fish in Kahnawake: risks and benefits.

Kahnawake is a Mohawk community located on the south shore of the Saint Lawrence River near Montreal. A comprehensive study was conducted in 1996-1997 to address the local concern regarding health risks of contaminant exposure associated with freshwater fish consumption. Forty-two participants, including most of the identified active fishermen (n=33), were interviewed. Walleye, perch, bullhead, and smallmouth bass were the species most consumed. Average daily intake of locally caught fish was 23 g/day. Nutrient and contaminant levels of locally collected fish were analyzed. Fish were good sources of protein, polyunsaturated fatty acids (particularly omega-3 fatty acids), calcium, zinc, and iron. Levels of cadmium, lead, arsenic, polychlorinated biphenyls (PCBs), and other chlorinated pesticides were at least 10 times lower than the guideline levels. Mercury levels of some predatory fish exceeded the guideline of 0.5 microgram/g. Average daily intakes of all contaminants were below the guideline levels by a factor of 10 except for mercury. Average mercury intake rate was about one-third that of the guideline level (200 micrograms/week). Contrary to residents' perception, Kahnawake fish were not particularly contaminated. In view of the nutritional as well as cultural benefits, fishing and fish consumption may be promoted.

Adolescent↗
PubMed2002

The relationship between fish intake and the prevalence of asthma: the Tokorozawa childhood asthma and pollinosis study.

OBJECTIVE: The Japanese have a higher intake of fish and a lower incidence of asthma than occupants of western countries. The present epidemiological study investigated the relationship between dietary fish intake and the prevalence of asthma among a childhood population. METHODS: Subjects represented all public elementary and junior high schools in Tokorozawa City in Japan (age range: 6-15 years old). The study population included 1,673 currently asthmatic students and 22,109 controls. Participants' parents completed the Japanese version of American Thoracic Society and Division of Lung Diseases, National Heart, Lung, and Blood Institute questionnaire for children, adopted by the Japan Environment Agency. We added supplementary questions (e.g., parental history of asthma and questions about frequency of foods eaten, including frequency of fish intake). Odds ratios for cases of current asthma according to frequency of fish intake were calculated, and a logistic regression analysis was used to adjust for possible confounding variables. RESULTS: After adjustments for age, gender, parental history of asthma, and vegetables and fruits intake, a significantly higher prevalence of asthma was noted among subjects who ate fish one to two times a week than among those who ate fish one to two times a month (adjusted odds ratio: 1.117; 95% confidence interval: 1.005-1.241; P = 0.041). The risk increased gradually with increasing frequency of fish intake, and the positive trend was statistically significant. CONCLUSIONS: The results indicated that frequency of fish intake was positively related to the prevalence of asthma. This result might have important implications for health.

Adolescent↗
PubMed1994

Regulation of cytochrome P4501A1 in teleosts: sustained induction of CYP1A1 mRNA, protein, and catalytic activity by 2,3,7,8-tetrachlorodibenzofuran in the marine fish Stenotomus chrysops.

Cytochrome P4501A1 (CYP1A1) is known to play important roles in the activation and detoxification of carcinogens and other toxicants in vertebrate animals, including fish. Although extensively studied in mammalian systems, the regulation of CYP1A forms in other vertebrates is less well understood. We examined the time course and dose-response relationships for induction of CYP1A1 mRNA, protein, and catalytic activity by 2,3,7,8-tetrachlorodibenzofuran (TCDF) in the marine fish Stenotomus chrysops (scup). The time course of CYP1A1 induction was determined following a single ip dose (10 nmol/kg) of 2,3,7,8-TCDF. Hepatic ethoxyresorufin O-deethylase activity was increased after 1 day, reached a maximum by 8 days, and was still elevated 14 days after treatment. The content of immunodetectable CYP1A1 protein in liver was elevated on Day 1 and continued to increase through 14 days. CYP1A1 protein content was also strongly induced in heart and gill beginning at 2 days after treatment and extending through Day 14. Hepatic CYP1A1 mRNA was strongly induced by 1 day after dosing and remained elevated through 14 days. The sustained induction of CYP1A1 mRNA by 2,3,7,8-TCDF contrasts with the transient induction seen previously in fish treated with nonhalogenated inducers and most likely reflects differences in persistence of the inducers. Dose-response studies indicated that induction of CYP1A1 mRNA, protein, and catalytic activity occurred following doses of 2,3,7,8-TCDF as low as 0.4 nmol/kg (120 ng/kg), within the range of whole-body contents of this congener measured in fish from contaminated environments. The estimated dose producing half-maximal CYP1A1 induction in scup was approximately 2-10 nmol/kg, suggesting that the sensitivity of these fish to induction may be as great as or greater than that of rats. In contrast to previous results obtained with 3,3',4,4'-tetrachlorobiphenyl (TCB) and beta-naphthoflavone, which appear to inhibit or inactivate CYP1A1 in fish and other vertebrates, there was a good correlation among levels of CYP1A1 mRNA, protein, and catalytic activity in individual fish following various doses of 2,3,7,8-TCDF. The difference in response to 2,3,7,8-TCDF versus 3,3',4,4'-TCB may reflect differences in the inducing potencies of the two compounds relative to their similar potencies as inhibitors of CYP1A1 catalytic activity. In additional studies to evaluate structure-activity relationships for CYP1A1 induction by chlorinated dibenzofurans in fish, scup were treated with 2,3,6,8-tetrachlorodibenzofuran (2,3,6,8-TCDF). At 10 or 50 nmol/kg, 2,3,6,8-TCDF was inactive as an inducer of CYP1A1 mRNA, protein, or catalytic activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Sister chromatid exchange analysis in cultured peripheral blood leukocytes of the coldwater marine fish, Pacific staghorn sculpin (Leptocottus armatus): a feasible system for assessing genotoxic marine pollutants.

The genotoxicity of environmental contaminants and test compounds to aquatic and marine fish has primarily been assessed by in vivo techniques that require sacrifice of the test organism for analysis. The major objective of this research was to develop an in vitro sister chromatid exchange (SCE) assay which would utilize cultured peripheral blood leukocytes (PBLs) of a coldwater marine fish species. Use of PBLs in cytogenetic genotoxicity tests has several advantages, the major one being that the experimental fish need not be sacrificed for sample collection. In addition, this nondestructive method of tissue collection permits the investigator to take multiple samples from a single individual and thereby allows the use of an individual as its own control and to monitor its SCE frequency over time. A suitable in vitro culture method for fish PBLs was a prerequisite for cytogenetic analysis of this tissue. The in vitro culture conditions necessary to provide a sufficient number of dividing cells for performance of the SCE assay were established in our laboratory for the PBLs of the Pacific staghorn sculpin (Leptocottus armatus), a common bottom-dwelling Puget Sound fish. The major components of this culture system are heparinized whole blood, fetal bovine serum-supplemented enriched tissue culture medium (RPMI 1640), purified protein derivative of tuberculin as a mitogen, and an incubation temperature of 13.5 degrees C. This in vitro PBL culture system is unique because it involves cultured blood cells from a coldwater marine fish species. Using this culture method, SCE induction was investigated in Pacific staghorn sculpin PBLs which had been exposed in vitro to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a known direct-acting inducer of SCEs. Cultured cells exposed in vitro responded to MNNG in a dose-related manner in regard to SCE induction, and the frequency of "outlier" cells increased at the higher concentrations of MNNG. With further development, this technique may be adaptable for use with in vivo genotoxicity studies and provide information concerning the induction and persistence of chemically induced SCEs in fish. This PBL/SCE assay may also be a feasible assessment tool for detecting exposure of marine fish to genotoxic environmental contaminants in laboratory and field situations.

Animals↗
PubMed1996

Sensory cues for the gradual frequency fall responses of the gymnotiform electric fish, Rhamphichthys rostratus.

The sensory cues for a less known form of frequency shifting behavior, gradual frequency falls, of electric organ discharges (EODs) in a pulse-type gymnotiform electric fish, Rhamphichthys rostratus, were identified. We found that the gradual frequency fall occurs independently of more commonly observed momentary phase shifting behavior, and is due to perturbation of sensory feedback of the fish's own EODs by EODs of neighboring fish. The following components were identified as essential features in the signal mixture of the fish's own and the neighbor's EOD pulses: (1) the neighbor's pulses must be placed within a few millisecond of the fish's own pulses, (2) the neighbor's pulses, presented singly at low frequencies (0.2-4 Hz), were sufficient, (3) the frequency of individual pulse presentation must be below 4 Hz, (4) amplitude modulation of the sensory feedback of the fish's own pulses induced by such insertions of the neighbor's pulses must contain a high frequency component: sinusoidal amplitude modulation of the fish's own EOD feedback at these low frequencies does not induce gradual frequency falls. Differential stimulation across body surfaces, which is required for the jamming avoidance response (JAR) of wave-type gymnotiform electric fish, was not necessary for this behavior. We propose a cascade of high-pass and low-pass frequency filters within the amplitude processing pathway in the central nervous system as the mechanism of the gradual frequency fall response.

Animals↗
PubMed1991

Fish diet and physical fitness in relation to membrane and serum lipids, prostanoid metabolism and platelet aggregation in female students.

The effects of a 14-week fish diet and exercise programme on lipid metabolism and platelet aggregation in healthy female students (n = 99) were studied. The subjects were divided into four groups: a control group, a fish diet group (3.5 meals containing fish per week, 0.9 g n-3 fatty acids per day), an exercise group (at least three training sessions per week) and a combined fish diet and exercise group. The proportion of n-3 fatty acids increased at the expense of n-6 fatty acids in platelets and erythrocyte ghosts in the fish diet groups. Serum triglyceride concentrations tended to decrease in the fish diet and exercise groups and a significant decrease was found in the combined fish diet and exercise group (13%, P less than 0.05). No significant changes took place in the other serum lipid and apolipoprotein concentrations. Platelet production of thromboxane B2, plasma 6-keto-PGF1 alpha concentrations and adenosine 5'-diphosphate (ADP)-induced platelet aggregation also remained unchanged in all groups during the study. However, an inverse correlation was found between physical fitness (maximal oxygen uptake and maximal exercise intensity) and serum triglycerides, total cholesterol, low density lipoprotein cholesterol and platelet aggregation. This suggests that improved physical fitness is related to beneficial changes in serum lipid concentrations and to a decreased aggregation tendency of platelets. The responses of the female subjects to a fish diet were smaller when compared to earlier studies on male subjects. This suggests that there are sex differences in the efficiency of n-3 fatty acids in modifying lipid metabolism.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Comparative study of myosins present in the lateral muscle of some fish: species variations in myosin isoforms and their distribution in red, pink and white muscle.

Myosin isoforms and their distribution in the various fibre types of the lateral muscle of eight teleost fish (representing a wide range of taxonomic groups and lifestyles) were investigated electrophoretically, histochemically and immunohistochemically. Polyclonal antisera were raised against slow (red muscle) and fast (white muscle) myosins of the mullet, and used to stain sections of lateral muscle. Antisera specific for fast and slow myosin heavy chains only (anti-FHC and anti-SHC respectively) and for whole fast and slow myosins (anti-F and anti-S respectively) were obtained, and their specificity was confirmed by immunoblotting against electrophoretically separated myofibrillar proteins. The ATPase activity of myosin isoforms was examined histochemically using methods to demonstrate their acid- and alkali-lability and their Ca-Mg dependent actomyosin ATPase. As expected, the predominant myosin (and fibre) type in the red muscle showed an alkali-labile ATPase activity, reacted with the anti-S and anti-SHC sera (but not anti-F or anti-FHC) and contained two 'slow' light chains, whereas the predominant myosin (and fibre) type in the white muscle showed an alkali-stable ATPase activity, reacted with anti-F and anti-FHC sera (but not anti-S or anti-SHC) and contained three 'fast' light chains. However, superimposed upon this basic pattern were a number of variations, many of them species-related. On analysis by two-dimensional gel electrophoresis fish myosin light chains LC1s, LC2s and LC2f migrated like the corresponding light chains of mammalian myosins, but fish LC1f consistently had a more acidic pI value than mammalian LC1f. Fish LC3f varied markedly in Mr in a species-related manner: in some fish (e.g. eel and mullet) the Mr value of LC3f was less than that for the other two light chains (as in mammalian myosin), whereas in others it was similar to that of LC2f (e.g. cat-fish) or even greater (e.g. goldfish). Species differences were also seen in the relative intensity of LC1f and LC3f spots given by the fish fast myosins. In most of the fish examined the red muscle layer showed some micro-heterogeneity, containing (in addition to the typical slow fibres) small numbers of fibres with a histo- and immunohistochemical profile typical of white muscle (fast) fibres. However, other immunohistochemically distinct minority fibres were found in the red muscle of the goldfish. Three types of pink muscle were distinguished: a mosaic of immunohistochemically typical red and white fibres (e.g. grey mullet).(ABSTRACT TRUNCATED AT 400 WORDS)

Anguilla↗
PubMed1994

Fish oil and the prevention and regression of atherosclerosis.

Epidemiological studies in the seventies have put forward that dietary rather than genetic factors are responsible for the lower incidence of ischemic heart disease in Greenland Inuit and have generated a large body of both in vitro and in vivo experimental studies, exploring the putative favorable effects of fish (oil) on atherogenesis and its risk factors. The first part of this report reviews the in vivo animal studies, concentrating on the hypercholesterolemic models and the arterialized vein graft model. In the hypercholesterolemic animal studies, the results are inconclusive as the studies reporting a protective effect are matched by the number of studies showing no effect or an adverse effect. The diversity in species, dose of fish oil, duration of study, type of vessel studied and type of fish oil preparation (content of n-3 fatty acids, unesterified n-3 fatty acids, ethylesters or triglycerides) could all contribute. Furthermore, the definitions and criteria used in the literature to evaluate atherogenesis are diverse and it appears that while one parameter is affected, another is not necessarily modified in the same direction, stressing the importance of extending the analysis of the effects on atherogenesis to more than one parameter. We also believe that it is time to reach a consensus as to which animal model mimics most closely a particular human situation. Only in appropriate models, investigating more than one atherosclerosis variable, can the effects of a putative anti-atherogenic drug or diet be verified. In the veno-arterial autograft model, mimicking the patient after coronary bypass grafting, dietary fish oil has been consistently effective in preventing accelerated graft intima proliferation. It could therefore be of interest to evaluate the effects of fish oil on graft patency in patients after coronary bypass surgery after a period of years. The results from studies on restenosis after percutaneous transluminal angioplasty are also reviewed and it is concluded that the two large scale trials, that are currently underway, might reliably answer the question whether fish oil is effective as a non-pharmacological adjuvants in the prevention of restenosis. Lastly, the studies on the effects of fish oil on the regression of experimental atherosclerosis are reviewed. In view of the small number of studies (i.e., four) investigating the effects of fish oil on the regression of atherosclerosis, it is premature to draw any conclusion, and therefore further experimental work is required.

Animals↗
PubMed1994

Different stability of posttranslationally modified brain microtubules isolated from cold-temperate fish.

Microtubule proteins were isolated by a temperature-dependent assembly-disassembly method from brain tissue of for cold-temperature fish; one fresh water fish (Oncorhynchus mykiss), and three marine fish (Labrus berggylta, Zoarces viviparus and Gadus morhua). The alpha-tubulins from all four fish species were acetylated. The alpha-tubulins from the marine fish were composed of a mixture of tyrosinated and detyrosinated tubulin, while the fresh water fish tubulin only reacted with an antibody against detyrosinated tubulin. The isolated microtubules had a similar MAP composition. A 400 kD protein and a MAP2-like protein were found, but MAP1 was missing. All microtubules disassembled upon cooling to 0 degrees C. In spite of these common characteristics, the assembly of microtubules from Labrus berggylta was inhibited by colchicine and calcium, in contrast to the assembly of microtubules from Oncorhynchus mykiss and Zoarces viviparus. For the latter, colchicine was not completely inhibitory even at a concentration as high as 1 mM, and calcium induced the formation of both loosely and densely coiled ribbons. The effects of calcium and colchicine on microtubules from Oncorhynchus mykiss and Zoarces viviparus were modulated by either fish or cow MAPs, indicating that the effects are due to intrinsic properties of the fish tubulins and not the MAPs. In view of these findings, our results suggest that there is no correlation between colchicine sensitivity, inability of calcium to inhibit microtubule assembly, and acetylation and detyrosination.

Acetylation↗
PubMed1995

[Thermogenesis and energy utilization of olive oil and fish oil in a model study with sows].

An animal model experiment was conducted with nine adult sows to study the effect of olive oil and fish oil (40% polyunsaturated fatty acids) on thermogenesis compared to wheat starch as control. The treatments were given to each animal according to a latin square design. The basal diet (20 g DM/kg W0.75) was mainly based on barley and soybean meal, and matched 60% of the ME requirements with all the other nutrients meeting maintenance requirements. The isoenergetic supplements amounted to 176 kJ gross energy per kg W0.75 and day. During each experimental period a complete energy balance was recorded for each animal using indirect calorimetry technique (RQ-method) as well as the carbon-nitrogen-balance technique. The treatments did not influence the digestibility of the rations. Digestibility of energy and of carbon averaged 83.4% and 83.3%, respectively. All three supplements were nearly completely digested as calculated by the difference method. Fish oil increased urine energy and decreased CH4 production, the shifts, however, were in absolute terms very small. The mean O2 consumption was 1,002 l/d showing no significant treatment effects. CO2 production was lowered with olive oil by 10%, and with fish oil by 13% compared to the starch diet. The daily heat production was 20.95, 20.72, and 20.04 MJ when starch, olive oil or fish oil was given. Corrected for equal energy retention the difference of thermogenesis between olive oil and starch was -0.4 MJ/d, and between fish oil and starch -1.2 MJ/d. These differences corresponded to a relation of starch:olive oil:fish oil = 1:0.95:0.86. The relation between starch and olive oil reflected exactly the theoretical expectation, calculated from the ATP regeneration by oxidation of both nutrients. When fish oil was added, the daily heat production was lower than theoretically calculated, which might be interpreted as an effect on the metabolic rate in general rather than especially on the efficiency of ATP formation from fish oil oxidation. In any case, there was no hint of a facultative thermogenesis induced by the oils.

Adenosine Triphosphate↗
PubMed1977

Mercury levels in freshwater fish of the state of South Carolina.

Samples of fish from freshwater sources of rivers, lakes and ponds all over the state of South Carolina were collected during the Summer of 1974 and 1975. The fish collected were Bass, Bluegill, Redbreast, Catfish, Shad, Carp, Crappie, Mudfish and Pike. Samples were analyzed using the flameless atomic absorption procedure outlined by Hatch and Ott, and Uthe et al as modified for use with Perkin-Elmer, Coleman MAS-50 mercury analyzer. Triplicate samples of fish tissue were analyzed by wet digestion method. The mean mercury levels in ppb were determined for baseline mercury levels. A significant finding of this report is that those species for which fish of widely differing weights were analyzed, larger fish had higher mercury levels. Mercury levels exceeding the U.S. Food and Drug Administration guideline of 500 ppb for fish tissues have been found in the Mudfish from Edisto River and Pike fish from Lake Murray. Higher levels of mercury occurred in the highly vascularized blood tissues of liver and kidney than in muscle. Carnivorous and bottom-feeding fishes are the most reliable indicators of mercury pollution.

Animals↗
PubMed1989

Fish oil prevents change in arachidonic acid and cholesterol content in rat caused by dietary cholesterol.

Rats were fed diets high in either saturated fat (beef tallow) or alpha-linolenic acid (linseed oil) or eicosapentaenoic and docosahexaenoic acids (fish oil) with or without 2% cholesterol supplementation. Consumption of linseed oil and fish oil diets for 28 days lowered arachidonic acid content of plasma, liver and heart phospholipids. Addition of 2% cholesterol to diets containing beef tallow or linseed oil lowered 20:4 omega 6 levels but failed to reduce 20:4 omega 6 levels when fed in combination with fish oil. Feeding omega 3 fatty acids lowered plasma cholesterol levels. Addition of 2% cholesterol to the beef tallow or linseed oil diet increased plasma cholesterol concentrations but not when fish oil was fed. Feeding the fish oil diet reduced the cholesterol content of liver, whereas feeding the linseed oil diet did not. Dietary cholesterol supplementation elevated the cholesterol concentration in liver in the order: linseed oil greater than beef tallow greater than fish oil (8.6-, 5.5-, 2.6-fold, respectively). Feeding fish oil and cholesterol apparently reduced 20:4 omega 6 levels in plasma and tissue lipids. Fish oil accentuates the 20:4 omega 6 lowering effect of dietary cholesterol and appears to prevent accumulation of cholesterol in plasma and tissue lipids under a high dietary load of cholesterol.

Animals↗
PubMed1994

Effect of dietary fish oil on blood levels of free fatty acids, ketone bodies and triacylglycerol in humans.

Although the reduction of serum triacylglycerol concentrations by dietary fish oil is a well-known effect, the exact mechanism of this effect has not been previously studied in human subjects. Therefore, the aim of this study was (i) to examine the effect of short-term fish oil supplementation on blood concentrations of ketone bodies, free fatty acids and triacylglycerol in healthy humans and (ii) to verify whether the observed relationships between these variables would be consistent with reduced lipolysis and/or enhanced hepatic fatty acid oxidation after fish oil supplementation. Twenty subjects (21-23 years, normal liver function tests) were randomly divided into two groups to supplement their usual diet with either 30 g/d of fish oil (n = 11) or olive oil (n = 9). Venous blood samples were drawn after an overnight fast, before and after 1, 3 and 7 d of fish oil/olive oil supplementation. Blood concentrations of triacylglycerol and free fatty acids decreased consistently after fish oil supplementation; the reduction was already significant after one day of fish oil (P < 0.001 for triacylglycerol and P = 0.01 for free fatty acids). In contrast, neither of these blood values changed after olive oil supplementation (P > 0.10). No significant changes in glucose, insulin or ketone body levels were observed in either group after supplementation. After fish oil, but not after olive oil supplementation, the ratio of blood ketone body levels to free fatty acid levels increased significantly (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2000

Accumulation of butyltin and phenyltin compounds in various fish species.

Concentrations of organotins (OTs) were measured in the muscle of 11 species of fishes from the Port of Osaka and Yodo River, Japan. Tributytin (TBT) and triphenyltin (TPT) compounds were detected in the range of 0.011-0.182 mg/kg wet weight and < 0.001-0.130 mg/kg wet weight, respectively. Concentrations of TBT were higher than those of TPT in the muscle of fish. Concentrations of OTs in fish from sea areas were higher than those from rivers, and the ratios of TBT to total butyltins (BTs) in fish from sea areas were also higher than those from rivers. A similar trend was found for TPT. Logarithm of bioconcentration factor (BCF) of TBT in fish was in the range of 2.7-3.9. No sex differences in TBT and TPT concentrations in Japanese sea perch were observed, and the concentrations of TBT and TPT were not related to total length of fish. No correlation was also observed between the concentration of TBT or TPT and lipid content. The concentrations of BTs and phenyltins (PTs) in organs and tissues of three fish species were determined. TBT was higher concentration in liver, brain, and muscle of white croaker and yellowtail. The ratios of TBT to the total BTs were 30-40%, and the ratios of TPT to total PTs in these fishes were greater than 50% of the total PT concentrations.

Animals↗
PubMed1997

Concentration, distribution, and comparison of selected trace elements in bed sediment and fish tissue in the South Platte River Basin, USA, 1992-1993.

During August-November 1992 and August 1993, bed sediment and fish liver were sampled in the South Platte River Basin and analyzed for 45 elements in bed sediment and 19 elements in fish liver. The results for aluminum, arsenic, cadmium, chromium, copper, iron, lead,manganese, selenium, silver, uranium, and zinc are presented here. All 12 trace elements were detected in bed sediment, but not all were detected in fish liver or in all species of fish. A background concentration of trace elements in bed sediment was calculated using the cumulative frequency curves of trace element concentrations at all sites. Arsenic, cadmium, copper, lead, manganese, silver, uranium, and zinc concentrations were greater than background concentrations at sites in mining areas or at sites that have natural sources of these elements. Trace element concentrations in fish liver generally did not follow the same patterns as concentrations in bed sediment, although concentrations of aluminum and cadmium were higher in fish liver collected at mountain sites that had been disturbed by mining. Concentrations of aluminum, arsenic, cadmium, chromium, copper, iron, lead, silver, and zinc increased in bed sediments in urban areas. Iron, silver, and zinc concentrations in fish liver also increased in urban areas. Concentrations of cadmium, copper, silver, and zinc in fish liver increased in the agricultural areas of the basin. Downstream changes in trace element concentrations may be the result of geological changes in addition to changes in land use along the river.

Animals↗
PubMed2004

Landscape character and fish assemblage structure and function in western Lake Superior streams: general relationships and identification of thresholds.

As part of a comparative watershed project investigating land-cover/land-use disturbance gradients for streams in the western Lake Superior Basin, we examined general relationships between landscape character and fish assemblage structure and function. We also examined the shape of those relationships to identify discontinuity thresholds where small changes in landscape character were associated with marked shifts in the fish assemblages. After completing a geographic analysis of second- and third-order watersheds in the western Lake Superior drainage, we randomly selected 48 streams along mature forest and watershed storage gradients in 2 hydrogeomorphic regions as our study sites. During the summers of 1997 and 1998, we used electrofishing to sample fish assemblages from each stream. Each of the landscape factors was significantly associated with fish assemblage structure and function based on analysis of covariance. Watershed storage was related to the greatest number of fish assemblage characteristics, but hydrogeopmorphic region and mature forest cover were strongly associated as well. The hydrogeomorphic region also mediated relationships between watershed character and fish assemblages. Discontinuity thresholds for our fish assemblages averaged 11% for watershed storage and 50% for watershed mature forest cover based on piecewise regression analysis. Although many of the landscape-fish relationships might have been manifest through effects on in-stream habitat, our results highlight the importance of management and land-use planning decisions at the watershed and landscape scales.

Animals↗
PubMed2005

Differential stress responses in fish from areas of high- and low-predation pressure.

We subjected fish from regions of high and low levels of predation pressure in four independent streams to a mild stressor and recorded their opercular beat rates. Fish from low-predation areas showed higher maximum, minimum and mean opercular beat frequencies than fish from high-predation regions. The change in opercular beat frequency (scope) was also significantly greater in fish from low- than in fish from high-predation regions. Under normal activity levels, however, low predation fish showed a reduced opercular beat frequency, which may be indicative of reduced activity levels or metabolic rate. Opercular beat frequency was negatively correlated with standard length as one would expect based on higher metabolic rates in smaller fish. We suggest that these contrasting stress responses are most likely the result of differential exposure to predators in fish from high- and low-predation areas. We argue that reduced stress responses in high-predation areas evolved to prevent excessive energy expenditure by modulating the fright response.

Adaptation, Physiological↗
PubMed2004

Fish protein improves blood pressure but alters HDL2 and HDL3 composition and tissue lipoprotein lipase activities in spontaneously hypertensive rats.

The two-month effects of dietary fish protein and casein on VLDL, HDL(2) and HDL(3) compositions and hepatic lipase (HTGL) and tissue lipoprotein lipase (LPL) activities were examined in spontaneously hypertensive rats (SHR) at 4 wk of age. After 2 mo of experiment, the fish protein diet induced lower blood pressure (-14 %) as compared to casein. Liver triacylglycerol and total cholesterol concentrations were 1.37- and 1.71-fold lower in the fish protein group than in the casein group, respectively. Total cholesterol concentration in plasma was also diminished by fish protein (-21 %) and was reflected in HDL(2) fraction (-44 %). SHR fed the fish protein diet as compared with those fed casein, showed a significantly low HDL(3) particle number, as measured by diminished HDL(3) mass and apo A-I. The consumption of fish protein did not affect VLDL particle number, but significantly decreased VLDL-triacylglycerol (-32 %) and adipose tissue total lipid concentrations as compared to casein. This was accompanied by diminished HTGL and adipose tissue LPL activities (-10%, -91%, respectively). These data demonstrate that fish protein plays an antihypertensive role and reduces plasma and tissue lipid concentrations. Thus, a fish protein intake might be beneficial for patients with hypertension.

Animals↗