Influence Of Fish Size Research Articles

Diet characteristics of tidal creek-associated fishes of the northeastern Arabian Sea with special reference to microplastic ingestion

The present study assessed the diet characteristics, trophic guild structure, and microplastics (MPs) ingestion by a group of fish sourced from the tidal creeks of the Mumbai coast along the Eastern Arabian Sea. The diet patterns were characterized using gastro-somatic index (GaSI), relative length of gut (RGL), diet overlap (α), diet breadth (Bi), and relative abundance of food items (%IOP), with a special emphasis on MPs contamination. The findings revealed that teleost and shrimps are the most preferred food items for these species. Whereas MPs contribute 5.50% of the total diet composition of the selected fishes. Additionally, we tried to find out the influence of fish size and dietary attributes on MP ingestion, identifying trophic level as a significant factor influencing contamination levels. Using the Polymer Hazard Index (PHI), the potential risks posed by MPs in fish samples were assessed, revealing notable discrepancies among polymers. For instance, polyvinyl chloride showed the highest PHI score of 198.75 and a hazard score reaching the highest risk category (IV), indicating substantial environmental risk. In summary, our findings highlight the impact of fish diet characteristics on MPs contamination and the varying levels of MP risks along the Mumbai coast, categorized according to polymer type from low to high risk.

Bioaccumulation of two macro-elements (Sodium and Potassium) in relation to body size and condition factor of Notopterus chitala from River Indus, Ghazi Ghat, Pakistan

Notopterus chitala is a member of the primitive teleost lineage and considered as commercially important food fish. To study the concentration of sodium and potassium and the influence of fish size and condition factor on the bioaccumulation of these macro-elements, a total of 16 fish specimens of N. chitala were collected from the River Indus. Mean (±SD) body weight, total length and condition factor was found 250.32±113.93 g, 32.93 ± 4.85 cm and 0.647± 0.094. Fish samples were oven dried, grinded, ashed and digested into 1M HNO3 to make sample solution. Flame atomic absorption measurements were analyzed to detect the concentration of sodium and potassium with atomic absorption spectrophotometer. Mean concentration of sodium was found 255.51± 32.45 µgg-1 with range values 206.28-298.70 µgg-1, while potassium was observed 1327.15 ± 234.71 µgg-1 with range 815.08-1694.87 µgg-1 in wet body weight of wild captured N. chitala. Body weight, total length and condition factor represented insignificant correlations with the concentrations of sodium and potassium in N. chitala, indicating no dependence of fish size on the bioaccumulation of these essential minerals in the body of this fish species.

Habitat associations and impacts on a juvenile fish host by a temperate gnathiid isopod.

The distribution and abundance of organisms is typically shaped by multiple biotic and abiotic processes. Micropredators are parasite-like organisms that are smaller than their hosts and/or prey and feed on multiple hosts during a given life stage. Unlike typical parasites, however, they spend much or most of their time free-living, associating only temporarily with hosts. In the ocean, micropredators can impact multiple fish species, and in particular can have significant lethal and sub-lethal effects on newly settled fish. Although gnathiid isopods are abundant and primary micropredators in coral reef ecosystems, their impacts are relatively unexplored within sub-tidal temperate rocky reefs. We investigated the distribution of juvenile gnathiid isopods along sub-tidal temperate rocky reefs and tested trap methodology. We also quantified both the sub-lethal and lethal impacts of feeding-stage juvenile gnathiid isopods on juvenile, post-settlement reef fish, Heterostichus rostratus (giant kelpfish). We were most interested in determining the relationship between gnathiid infestation level and fish swimming performance, in particular swimming metrics relevant to predator avoidance maneuvers. We found that Gnathia tridens was present in rocky reefs rather than embayments along the Southern California coastline and that within rocky reefs, gnathiids occurred in the highest densities in lighted traps. Surprisingly, we observed almost no influence of fish size or gnathiid sub-lethal infestation level on ambient or burst swimming performance metrics. However, burst duration was reduced by gnathiid infestation, which is important in predator avoidance. There were significant differences in survivorship among small fish compared to large fish as a result of gnathiid infestation. Larger fish survived higher numbers of gnathiids than smaller fish, indicating that parasite-induced mortality is greater for smaller fish. Investigations of the effects of micropredators on subsequent predator-mediated mortality, including the susceptibility of fishes and their individual responses to micropredators, can further contribute to our understanding of processes affecting recruitment in resident reef fish populations. Further research, especially within temperate sub-tidal ecosystems, is needed to understand and highlight the overlooked importance of micropredation in shaping fish populations within a reefscape.

Mercury and selenium levels in archive samples of wild Atlantic bluefin tuna from the Mediterranean Sea

This study examined total mercury (THg) and selenium (Se) levels in archive samples (white and red muscles, liver, gills) of the wild Atlantic bluefin tuna (ABFT) (Thunnus thynnus) (n = 18) captured in the central Adriatic Sea. The influence of fish size, age, and tissue type on element distribution was examined. There were significant differences in THg and Se levels, and Se:THg molar ratios among tissues. THg levels were highest in liver and lowest in gills (liver > red muscle > white muscle > gills), while Se levels were also highest in liver but lowest in white muscle (liver > red muscle > gills > white muscle). Se:THg molar ratios were highest in gills (22–82), intermediate in liver (11–29) and red muscle (7–36), and lowest in white muscle (1.7–7.6). Concentrations of THg in all tissues and Se in liver and caudal muscle were positively correlated with tuna age and size, while the Se:THg molar ratio in gills and all white muscles was negatively correlated with tuna age and size, indicating that the protective role of Se against THg is reduced in older specimens. The selenium health benefit values (HBVSe) were above zero in all tissues, indicating a small excess of Se after Hg sequestration. However, since the obtained HBVSe for edible tissues were near zero (0.01–0.04), and more than 70% of white muscle samples and all red muscle samples exceeded the EU regulatory limit for THg in fish muscle, it would be advisable to limit their intake in adults to one meal per month.

Juvenile Oblada melanura (L. 1758) otolith shape variation as an early environmental indicator

Abstract Coasts are increasingly subject to the pressure of human activities, thus bioindicators of stress are also becoming necessary. We tested whether the otolith shape of Oblada melanura juveniles could be used as indicator of anthropic impacts. Otolith shapes, defined by Fourier elliptic analysis, were compared using canonical analysis of principal coordinates. In this three-year study, we compared two geographically close sites: one with low-level pollution and one near a recreational harbour. Determining the minimum fish standard length at which the influence of fish size on otolith shape does not occult other influences, 11 mm in this study, is a prerequisite for the study of otolith shape variation in juveniles. Inter-annual environmental variations interfere with local conditions and delays between samplings are also important considerations. We have demonstrated that the comparison of O. melanura juvenile otolith shape is an effective method to compare the short-term influence of different environmental conditions.

Per- and poly-fluoroalkyl compounds in freshwater fish from the Rhône River: Influence of fish size, diet, prey contamination and biotransformation

Pools of aquatic plants and benthic invertebrates were collected along with 47 individuals from three cyprinid fish species (Barbus barbus, Gobio gobio, Rutilus rutilus) at a site in the Rhône River (France). Carbon and nitrogen isotopic ratios (δ13C and δ15N) and a wide range of per- and poly-fluorinated chemicals (PFASs) were analysed in all samples. The sum of PFAS concentrations (ΣPFAS) increased from aquatic plants to fish dorsal muscles; molecular profiles were dominated by C9–C13 perfluorocarboxylic acids (PFCAs), while perfluorooctane sulfonate (PFOS) and perfluorooctane sulfonamide (FOSA) were detected in all samples at lower concentrations. ΣPFAS and especially ΣPFCAs were higher in barbels (B. barbus) than in other species, while roaches (R. rutilus) were less contaminated by PFOS than barbels and gudgeons (G. gobio). Gudgeons accumulated significantly higher FOSA concentrations. Young (small) barbels displayed significantly higher PFOS, perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) concentrations than did large specimens; conversely, perfluorotetradecanoic acid (PFTeDA) concentrations were significantly higher in large barbels. Multiple linear regressions were performed on the whole set of fish samples with size, mass and isotopic ratios as explicative variables, and several single compounds as explained variables. Regardless of the compound, the regressions did not explain much of the contamination variability. However, adding species as a qualitative variable, i.e. performing analyses of covariance (ANCOVAs) improved the fit greatly, while adding sex did not. Diet (i.e. δ13C and δ15N) was the main factor explaining interspecific differences. Biotransformation was assessed by comparing concentration ratios of PFOS or FOSA to their precursors in the food-web compartments. These ratios increased from invertebrates to fish, and differed among fish species, suggesting that biotransformation occurred but was species-specific. Biomagnification factor calculations showed that C11–C13 PFCAs, PFOS and FOSA were apparently biomagnified in barbels and gudgeons.

Effects of size and diet on stable hydrogen isotope values (δD) in fish: implications for tracing origins of individuals and their food sources

Recent studies suggest that stable hydrogen isotope ratios (δD) of fish can be used to track their watershed origin and the relative contributions of source material. Both applications assume that there is no metabolic or trophic effect on tissue δD. We studied the local variation of δD values in four fish species of contrasting size and feeding habits in an isotopically homogenous reservoir (Flix, Spain). Other isotopic values (δ15N, δ13C) and trace metal content were measured as indicators of trophic and bioaccumulation patterns. In addition, isotopic values (δD, δ15N, δ13C) of other food web components were measured for comparison. Muscle δD values differed greatly among fish species: European catfish, Silurus glanis (–131‰); common carp, Cyprinus carpio (–141‰); rudd, Scardinius erythrophthalmus (–158‰); and roach, Rutilus rutilus (–163‰). The influence of fish size and trophic position affected the fish δD values. Possible mechanisms that drive δD variation among fish might be a metabolic effect and (or) the compounding effect of ambient water δD on exchangeable H at each trophic stage. Our findings showed that size and feeding habits are factors that should be controlled when tracing origins of fish or their dependence on nutrient inputs using δD measurements.

Influence of fish size and sex on mercury/PCB concentration: Importance for fish consumption advisories

Fish advisories for polychlorinated biphenyls (total-PCBs) and mercury are often given on a length-specific basis and fish sex is usually not considered. The relationship between concentration and length is well established for mercury, however its suitability for total-PCBs and the influence of sex over the large scale covered by most monitoring programs is not well known. Here we use what is perhaps the largest consistent sport fish contaminant dataset to evaluate the relationship between total-PCB/mercury and length and sex. We evaluated seven of the most commonly consumed fishes from the Canadian Great Lakes and two Ontario (Canada) inland lakes. For mercury, the relationship between concentration and length was significant ( p < 0.05) in most fish species and locations. For total-PCB, this relationship was also generally significant in Chinook salmon and lake trout, which are the species with the most advisories for this compound. In contrast, significant relationships were found less often for whitefish, northern pike, smallmouth bass, walleye, and especially yellow perch. However, mercury usually drives fish consumption advisories for these species. Overall, our results support the protocol of issuing contaminant advice on a length-specific basis in fish monitoring programs with reasonable confidence when at least a moderate number of samples over the natural size range of a species are included in the analysis. Sex differences were common for walleye (males > females, p < 0.05) but not other species, suggesting that an equal number of male and female walleye should be used in deriving fish advisories for walleye.

Improving the mechanical characteristics of faecal waste in rainbow trout: the influence of fish size and treatment with a non-starch polysaccharide (guar gum)

This study (3 × 2 randomized factorial design) describes differences in the mechanical properties of faeces from rainbow trout of three size classes (small ≈40 g, mid-size ≈150 g, large ≈650 g) and assesses the effects of a non-starch polysaccharide binder (guar gum). Observations made at the macroscopic level were reinforced by rheological measurements of viscosity and elastic modulus. Mid-sized fish excreted mechanically the most stable faeces, roughly twice as stable as those of small fish and three times more stable than faeces from large fish. The addition of 3 g kg−1 of guar gum saw some mechanical characteristics improve by about 700%. Faeces from large- and mid-sized fish were more easily stabilized than those of small fish. Mechanical recovery potential for faecal samples disrupted by water turbulence was determined. Stability differences observed for different fish size had no significant effect but the improvements imparted by guar gum reduced postfiltration effluent load to about 35% for large fish, about 24% for mid-size and about 22% for small fish. Faecal leaching decreased significantly with increasing stability. Guar gum was shown to have significant potential for improving the treatability of fish faecal waste.

Three species of fishes from an eutrophic, seasonally alkaline lake are not more tolerant to acute exposure to high pH in the laboratory

A number of different freshwater fish species (perch Perca fluviatilis, roach Rutilus rutilus and rudd Scardinius erythrophthalamus) from either eutrophic (Slapton Ley, a seasonally alkaline lake) or non‐eutrophic waters were compared with respect to their sodium uptake kinetics and tolerance to acute (1 h) exposure to pH 9·5. Further comparisons were made with rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta. The influence of fish size was also investigated in rainbow trout. Exposure to pH 9·5 was found to disrupt sodium balance and inhibit ammonia excretion in all species and sizes of fishes. The origin of fishes did not have a significant effect on the sodium uptake kinetics or the physiological responses to high pH water. The fishes from the eutrophic lake therefore did not appear to have any increased tolerance to acute exposure to alkaline water. In contrast to previous studies there was no inhibition of Na+ uptake during exposure to high pH. Indeed in some groups of fish Na+ uptake was actually stimulated, as was Na+ efflux. These differences are attributed to experimental water composition and interspecific differences in physiology. It was not always possible to size‐match fishes of the different species, so rainbow trout were used to assess the effect of body mass (from 2 to 40 g), on Na+ uptake kinetics and Na+ or ammonia fluxes during alkaline water exposure in rainbow trout. Size had no significant effect on these measurements within this narrow range, which helps validate the comparison between species in this study.

Influence of fish size and water temperature on the metabolic demand for oxygen by barramundi, Lates calcarifer (Bloch), in freshwater

Oxygen demand by all animals is driven primarily by their needs for sustaining metabolism. Typically, larger animals require more oxygen and cellular fuel to carry out respiration than smaller animals. This relationship in most cases is not linear and is usually described by a coefficient and exponent (e.g. axb): the exponent b showing the relationship between live-weight and energy/oxygen demand and is often termed the metabolic body weight (MBW) exponent, while the coefficient (a) tends to be temperature specific and describes the relationship between MBW and maintenance metabolic energy and oxygen demand at that specific temperature. Across all temperatures (range 26.0–32.0°C), the relationship between barramundi (Lates calcarifer) live-weight (x; g) and relative oxygen consumption as standard metabolic rate (y; mg O2 kg−1 h−1) at 29.4±1.5°C (mean±SD) was described by the exponential curve: y=710.19 x−0.3268, R2=0.6875 (n=222 assessments). Examination of the same data but on a gross oxygen consumption (mg O2 h−1) basis showed a relationship between live-weight (x; g) and gross oxygen consumption (y; mg O2 h−1) that was described by the exponential curve: y=0.710 x0.6732, R2=0.9033. Evaluation of the combined relationship between fish live-weight (y; g) and water temperature (x; °C) on gross oxygen consumption rate (z; mg O2 h−1) was described by the equation: z=(−20.7818+1.4017x−0.0227x2) ×y0.673.

Effects of stream enclosures on drifting invertebrates and fish growth

AbstractStream ecologists often use enclosure experiments to investigate predator–prey interactions and competition within and among fish species. The design of enclosures, manipulation of species densities, and method of replication may influence experimental results. We designed an experiment with enclosure cages (1 m2, 6-mm mesh) to examine the relative influence of fish size, density, and prey availability on growth of brown trout (Salmo trutta), brook trout (Salvelinus fontinalis), and slimy sculpin (Cottus cognatus) within enclosures in Valley Creek, Minnesota. In addition, we examined water flow and invertebrate drift entering enclosures and in open riffles to investigate whether enclosures reduced the supply of invertebrate prey. Growth of small (age-0) brook and brown trout was not influenced by fish density, but growth of larger (age-1) trout generally decreased as density increased. Sculpin growth was not related to fish size or density, but increased with mean size of invertebrates in the drif...

Long‐term dynamics of Chernobyl 137Cs in freshwater fish: quantifying the effect of body size and trophic level

Summary 1. Freshwater fish are a potentially important link in the transfer of radionuclides from polluted ecosystems to people. A pulsed contamination event such as the Chernobyl fallout in 1986 is a challenge to the prediction of radioactivity in biota, because activity concentrations of radionuclides can change dynamically among populations during an initial equilibration phase. This was demonstrated from time‐series of 137caesium (Cs) in fish from three Swedish lakes (1986–2000, eight species, &gt; 7600 individuals). In addition, we used these data to test hypotheses about the influence of fish size and trophic level on the temporal patterns of 137Cs. 2. In order to facilitate comparisons, a pulse‐response model was developed to extract key parameters from field data: the timing (tmax) and level (Csmax) of the peak concentrations, the near steady‐state level (Csbase) and the long‐term decline rate (λ). 3. Peak concentrations in different fish were attained 56–806 days after the fallout. This delay (tmax) increased with body size and trophic level. Csmax increased with fish size but was highest at intermediate trophic levels. Csbase increased by a factor of 1·8 per trophic level, but was not influenced by size across species. The 137Cs‐size relationship within species, however, shifted from negative to positive during the first 2 years. 4. The apparent ecological half‐life (T1/2) for 137Cs increased after tmax and initially differed among fish and lakes. About 10 years after the fallout T1/2 was no longer significantly different among fish or lakes, suggesting that steady‐state among 137Cs levels in fish had been reached. The mean T1/2 during 1996–2000 was 46 years, implying that the future recovery from present 137Cs levels (more than 10‐fold higher than pre‐Chernobyl levels) will be dominated by the physical decay of 137Cs (30 years). 5. The influence of fish size and trophic level on 137Cs dynamics has been consistent among the three lakes. The duration of the 137Cs pulse in fish appeared to be regulated by fish ecophysiology, whereas the amplitude also appeared to be regulated by lake characteristics. 6. Synthesis and applications. These data have implications for the predictive modelling of pulsed contaminants in lake ecosystems and show that (i) complex temporal concentration trends in fish can be adequately modelled by a combination of simple first‐order equations; (ii) a one‐component decline function is insufficient to describe the observed increase in ecological half‐life over time; (iii) fish weight and trophic level can and should be treated as independent variables because their influence differs and changes over time. For management purposes, a pulse‐response model for fish can be scaled to different systems by using established relationships to account for differences in fallout and catchment biogeochemistry.

The influence of fish size on the avoidance of hypoxia and oxygen selection by largemouth bass

The influence of fish size on the avoidance of hypoxia and oxygen selection by largemouth bass

Energy Digestibility Coefficients of Commonly Used Feedstuffs in Different Size-Classes of Indian Major Carps, Labeo rohita (Hamilton) and Cirrhinus mrigala (Hamilton)

The apparent energy digestibility coefficient of nine different feedstuffs were determined for two size-classes of Indian major carps (Labeo rohita and Cirrhinus mrigala., Cyprinidae) using chromic oxide as the indigestible marker. Among the ingredients tested, rice polish showed the lowest while the soybean oil cake showed the highest digestibility in both species. The influence of fish size on energy digestibility was found to be insignifi­cant (P&gt;0.01). Irrespective of fish size, plant and animal origin feed stuffs showed no sig­nificant (P&gt;0.01) difference in their digestibility in both species. Only the animal origin feed stuffs, in both size-classes, exhibited species dependent variability in their digestibility.

Influence of fish size on proliferation and differentiation of cultured myosatellite cells of white axial muscle of carp ( Cyprinus carpio L.)

Abstract The in vitro proliferation [uptake of 5-bromo-2′-deoxyuridine (BrdU)] and the degree of differentiation (presence of desmin) of myosatellite cells isolated from white axial muscle of carp between 3 cm and 27 cm standard length (SL) were examined 17 h after isolation. The fraction of the myosatellite cells that were both desmin positive and BrdU positive never exceeded 2% of the total number of isolated myosatellite cells, irrespective of the standard length of the donor(s). This indicates that, for carp, the temporal relationship between replication and desmin expression of myosatellite cells is different from that described for myogenic cells of mammals and birds. The percentage of BrdU positive myosatellite cells was significantly correlated with standard length: it increased from 10% for carp of about 5 cm SL to 40–50% for carp between 20 cm and 27 cm SL. The percentage of desmin positive myosatellite cells was about 50–60%; it was not significantly correlated with standard length. The percentage of myosatellite cells that were both BrdU negative and desmin negative showed a stepwise difference in this percentage with increasing length. Fish smaller than 10 cm SL, had more of these cells (10–40%), than larger fish (which had 0–12%). So, apparently the composition of the myosatellite cell population changes during growth. The low percentage of proliferating cells, and the relatively high percentage of differentiated (desmin positive) myosatellite cells obtained from 3–6 cm large carp, suggests that, in these small fish, muscle growth strongly depends on the use of a pool of myogenic cells that has been formed at an earlier stage of their development.

Influence of Fish Size, Origin, and Stress on Ascorbate Concentration in Vital Tissues of Hatchery Rainbow Trout

Abstract One-year-old rainbow trout (Oncorhynchus mykiss of probable steelhead origin) were analyzed for total ascorbate and dehydroascorbate concentrations before stocking and after transportation stress. Fish were reared on practical diets containing 0–60 mg total ascorbate per kilogram in state hatcheries in Ohio and New York. We concentrated on the influence of origin, fish size, and stress of short duration on ascorbate status in vital tissues. Liver ascorbate concentrations varied significantly between hatcheries – 78.9 ± 15.6 μg/g at Altmar, New York, and 123.6 ± 32.7 μg/g at London, Ohio – and were highly correlated with fish size (r = –0.572,N= 57). In fish subjected to hauling stress, liver and kidney ascorbate increased, whereas the dehydroascorbate decreased significantly if the fish size variable was included in the analysis. The livers, kidneys, and intestines of rainbow trout reared under practical hatchery conditions showed moderate levels of ascorbate compared with organs of fish experime...