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Body Length (body + length)
Kinds of Body Length Selected AbstractsLENGTH-MASS AND TOTAL BODY LENGTH OF ADULT FEMALE SEA OTTERS IN PRINCE WILLIAM SOUND BEFORE AND AFTER THE EXXON VALDEZ OIL SPILLMARINE MAMMAL SCIENCE, Issue 4 2002Lisa Mignon Rotterman Abstract After the 1989 T/V Exxon Valdez oil spill (EVOS), the body condition of non-pregnant female sea otters (Enhydra lutris) ages 4 yr and older in the EVOS-affected region of western Prince William Sound, Alaska (WPWS), was significantly poorer than that of individuals captured in the same or adjacent habitat in WPWS approximately a decade earlier, and than that of individuals inhabiting unoiled habitat in eastern PWS (EPWS) between 1984 and 1990. However, the body condition of females of this age category captured in WPWS prior to EVOS was not significantly different from that of pre-and postspill EPWS females. The mean total body length (TBL) of non-pregnant females captured prespill in WPWS was significantly less than that of pre-and postspill EPWS and postspill WPWS females. Evidence from this and other studies suggests that the body condition of at least some classes of sea otters was negatively affected by one or more EVOS-related factors. [source] Laboratory-based reproduction success of ruffe, Gymnocephalus cernuus (L.), in brackish water is determined by maternal propertiesECOLOGY OF FRESHWATER FISH, Issue 2 2006A. Albert Abstract,, Body length, age, egg size, embryo salinity tolerance and length at hatching of the freshwater (salinity <0.1 ppt, Lake Peipsi) and brackish-water (salinity 2,6 ppt, Pärnu and Matsalu Bay) ruffe, Gymnocephalus cernuus (L.), were examined to reveal their reproductive success in moderate salinity. Eggs of females originating from brackish water were significantly larger than eggs of freshwater females. No correlation between egg size and female size and age was found in brackish-water populations. In the freshwater population there was a small negative correlation between egg size and female size, but no correlation with female age. Fertilisation by sperm of males of different origin (brackish water or freshwater) produced no significant differences at any critical developmental stage (fertilisation, gastrulation, hatching) in the development of eggs from brackish-water or freshwater females at 3.3, 5.5, 7.7 and 9.9 ppt salinity. Survival rates in different salinity depended only on female origin; embryonic salinity tolerance was higher in ruffe inhabiting brackish water. Obviously, embryo salinity tolerance in ruffe is determined by egg qualities. [source] Generalised regressions provide good estimates of insect and spider biomass in the monsoonal tropics of AustraliaAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 3 2006Christopher J Brady Abstract, The estimation of arthropod biomass is often important in studies of terrestrial ecosystem structure and function, including analyses of the relative importance of different arthropod taxa in the diet of insectivorous animals. In order to estimate arthropod biomass in eucalypt woodlands and rehabilitated mine-land in the monsoonal tropics of northern Australia, insect morpho-species (n = 693) and spider morpho-species (n = 100) were collected, sorted, then weighed and measured. Body length,weight regressions were determined for spiders, nine insect orders and all insects combined. There was a significant relationship between body length and weight for all taxonomic groups, with the power model being a better predictor than linear or exponential models for all groups except Diptera (which was best predicted by the linear model). Whilst Schoener (1980) found that the length,weight regression slopes of neotropical insects (all orders combined, as well as several individual orders) differed from those of their temperate North American counterparts, our comparisons between monsoon-tropical and temperate Australian arthropods suggested differences among Dipterans and spiders only. We conclude that generalised regressions provide adequate estimates of arthropod biomass across Australia, providing that the body proportions of the dominant taxa do not vary substantively. [source] Effects of in utero exposure to 2,2,,4,4,,5,5,-hexachlorobiphenyl (PCB 153) on somatic growth and endocrine status in rat offspringCONGENITAL ANOMALIES, Issue 4 2008Kenichi Kobayashi ABSTRACT Exposure to polychlorobiphenyl (PCB) mixtures at an early stage of development has been reported to affect endocrine glands; however, little is known about the precise toxicological properties of individual PCB. The present study was undertaken to determine whether prenatal exposure to 2,2,,4,4,,5,5,-hexachlorobiphenyl (PCB 153), a di- ortho -substituted non-coplanar congener, affects postnatal development in rat offspring. Pregnant Sprague-Dawley rats (Crj: CD (SD) IGS) were given PCB 153 (0, 16, or 64 mg/kg/day) orally from gestational day (GD) 10 through GD 16, and developmental parameters in the male and female offspring were examined. We found no dose-dependent changes in body weight, body length (nose,anus length), tail length, or the weights of kidneys, testes, ovaries and uterus in offspring at 1 or 3 weeks of age. Liver weights were increased in the PCB 153,treated groups, although we observed a significant difference only in males. Anogenital distance was unaffected in the PCB 153,treated groups. We observed a significant dose-dependent decrease in the plasma concentrations of thyroxine and tri-iodothyronine, whereas those of thyroid-stimulating hormone were not significantly changed. In addition, there were no dose-dependent changes in plasma concentrations of growth hormone and insulin-like growth factor-I in any dose group. These findings suggest that prenatal exposure to PCB 153 (GD 10,16, 16,64 mg/kg/day) may alter the thyroid status in rat offspring to some extent without affecting somatic growth or its related hormonal parameters. [source] On the morphology of Acanthostomum spiniceps (Looss, 1896) and A. absconditum (Looss, 1901) (Digenea: Cryptogonimidae: Acanthostominae) with particular reference to the juvenile stageACTA ZOOLOGICA, Issue 3 2006Mohammed Hasan Ibraheem Abstract The morphology of juvenile and adult stages of Acanthostomum spiniceps and A. absconditum, from bagrid fish of the river Nile in Egypt, was studied with both light and scanning electron microscopy. In early juveniles, circumoral spines are absent and the entire body surface is covered with tegumental spines. Late juveniles show gradual differentiation of the circumoral tegument into a collar of spines associated with a reduction in density of tegumental spines at the posterior extremity of the body. Genital primordia appear when juveniles are about 1.75 mm long. The distributions of tegumental spines on adult A. spiniceps and A. absconditum are similar. Spines are denser on the dorsal and ventral surfaces of the anterior and middle parts of the body and less dense towards the posterior end. The tegumental fold surrounding the ventral sucker of A. absconditum has spines while the fold of A. spiniceps lacks them. The most important morphological features differentiating both species are the number of circumoral spines, body shape, ratio of body length to width, sucker sizes, and the presence or absence of spines on the ventral sucker. [source] Barchan-shaped ripple marks in a wave flumeEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2004Noritaka Endo Abstract Barchans, isolated crescent-shaped bedforms, are believed to be formed under almost unidirectional wind or water ,ows and limited sand supply. The formation of barchan morphologies under the action of purely oscillatory wave motion has not yet been fully investigated. The present study attempted to form barchan topography in a wave ,ume and to compare this with barchans in the ,eld. Barchan morphologies of ripple size, called the barchan ripples, were generated from a ,at bed by the action of waves. The horn width, the distance between horn tips, of the barchan ripples increased linearly with an increase in the total length, the overall length projected on the centre line of the barchan, with a coef,cient common to barchan dunes in deserts. The ratio of horn length to horn width of the barchan ripples was smaller than that of barchan dunes, but similar to that of subaqueous barchans in the ,eld. The longer the wave period was, the larger the ratio of the body length to horn width became. Most subaqueous barchans formed under waves (in the laboratory) and unidirectional ,ows (in the ,eld) had blunter horns than subaerial barchans. The shape of the barchan ripples changed with wave period. The outer rim became rounder with increasing wave period. The relationship between the base area and the height of barchan morphologies seems to be linear, with a constant coef,cient for the scale from ripples to dunes. The barchan ripples showed a linear relationship between the height and the horn width, similar to that for barchan dunes. The migration speed of the barchan ripples was proportional to the cube of the ,ow velocity and was inversely proportional to height. The same relation with a different value of the coef,cient was obtained for barchan dunes. Copyright © 2004 John Wiley & Sons, Ltd. [source] Environmental features influencing Carabid beetle (Coleoptera) assemblages along a recently deglaciated area in the Alpine regionECOLOGICAL ENTOMOLOGY, Issue 6 2007MAURO GOBBI Abstract 1.,The spatio-temporal approach was used to evaluate the environmental features influencing carabid beetle assemblages along a chronosequence of an Italian Alpine glacier foreland. The influence of environmental variables on species richness, morphology (wing and body length), and distribution along the chronosequence was tested. 2.,Species richness was found to be a poor indicator of habitat due to weak influences by environmental variables. It seems that the neighbouring habitats of a glacier foreland are not able to determine significant changes in carabid species richness. 3.,Instead it appears that history (age since deglaciation) and habitat architecture of a glacier foreland are strongly correlated to species adaptive morphological traits, such as wing morphology and body length. Assemblages characterised by species with reduced wing size are linked to the older stages of the chronosequence, where habitat is more structured. Assemblages characterised by the largest species are linked to the younger sites near the glacier. These morphological differentiations are explained in detail. 4.,Habitat age can therefore be considered the main force determining assemblage composition. On the basis of the relationship between morphological traits and environmental variables, it seems likely that age since deglaciation is the main variable influencing habitat structure (primary effect) on the Forni foreland. The strong relationship between carabid assemblages and habitat type indicates that site age has but a secondary effect on carabid assemblages. This may be utilised to interpret potential changes in assemblages linked to future glacier retreat. [source] Total population density during the first year of life as a major determinant of lifetime body-length trajectory in marble troutECOLOGY OF FRESHWATER FISH, Issue 4 2008S. Vincenzi Abstract,,, The conditions experienced early in life can strongly influence life-history trajectories in a variety of animal species. Here, we use data from four isolated populations of the endangered stream-dwelling salmonid marble trout (Salmo marmoratus Cuvier 1817) living in the Soca and Idrijca river basins (Slovenia) to explore the influence of the total density experienced during and after the first year of life by marble trout year-classes on body length of marble trout through the lifetime. Analyses were performed by pooling together the stream-specific datasets to cover a wider range of densities. Mean body length of marble trout year-classes through the lifetime (from age 1+ to 5+) was negatively related to total density of marble trout during the first year of life. The relationship between density during the first growth period and body length through the lifetime was well described by negative power curves. Total population density after the first year of life was not correlated with body length, thus suggesting that body growth trajectories are heavily determined early in life. Given size-dependent sexual maturity and egg production in marble trout, the relationship between density early in life and lifetime individual growth may have strong implications in terms of population dynamics and regulation of population size. [source] Tooth size and skin thickness in mature sockeye salmon: evidence for habitat constraints and variable investment between the sexesECOLOGY OF FRESHWATER FISH, Issue 3 2006S. P. Johnson Abstract ,, Pacific salmon develop many sexually dimorphic features at maturity, and the extent of development varies among populations. In this study, we compared a suite of traits including body length, body depth, jaw length, tooth size and skin mass in male and female sockeye salmon breeding in beach and creek habitats. Both tooth size and skin mass varied positively with body length. Within each of the breeding habitats, males had longer teeth than females, and within each sex, beach spawners had longer teeth than creek spawners. Males also had heavier skin than females in each habitat but, unlike the case with tooth size, creek spawners showed a much stronger relationship between skin mass and body length than did beach spawners. Tooth length was positively related to jaw length and skin mass among individuals within a given sex and habitat. Taken together, these results suggested that variation in tooth size parallels variation in other sexually dimorphic traits. Males and beach spawners tend to exhibit large trait values relative to females and creek spawners, and ,well-endowed' individuals displayed high values of all traits rather than a trade-off as might occur if investment in one trait compromised investment in others. However, the finding that creek fish tended to have thicker skin for a given body length than did beach fish suggested that factors other than merely defense against conspecifics during battle, such as abrasion and desiccation resistance in small streams, may influence the evolution of skin mass in mature sockeye salmon. [source] Residency and movement of stream-dwelling Japanese charr, Salvelinus leucomaenis, in a central Japanese mountain streamECOLOGY OF FRESHWATER FISH, Issue 3 2002T. Nakamura Abstract,,,The residency and movement of stream-dwelling adult (2+ and older) Japanese charr, Salvelinus leucomaenis, were studied by mark and recapture experiments in the Jadani Stream, a headwater tributary of the Tedori River, central Japan, from 1986 to 1989. Of the marked fish, 31.3,58.3% were recaptured in the same pools where they had been caught during the study periods of summer (June,August), autumn (August,November) and winter,spring (November to the next June) and no seasonal movement was observed. The mean distances that the fish moved during the study periods ranged from 139.0 to 502.3 m and many movements longer than 1000 m were observed. Between the resident and the moved fish, there was little difference in body length, growth rate or sex. For the fish that had been resident in the same pools and riffles at previous recaptures, most fish were recaptures in the same locations at the next recapture. Conversely, for the fish that moved previously, most fish were recaptured in different locations from previous sites at the next recapture. These results suggest that Japanese charr exhibit relatively high residency throughout the year, but many fish moved longer distance. The results also suggest the presence of static and mobile components in the charr population. [source] Population persistence of the parasitoid fly Zaira cinerea (Fallén) (Diptera: Tachinidae) utilizing multiple host carabid beetles with different seasonality and qualityENTOMOLOGICAL SCIENCE, Issue 3 2010Atsushi OHWAKI Abstract Zaira cinerea (Fallén) is a parasitoid fly (Diptera: Tachinidae) that attacks adult carabid beetles. To better understand mechanisms of population persistence in this species, we examined seasonality of host beetle abundance, the frequency of parasitism, and the timing of fly eclosion. In addition, we evaluated host quality using numbers of larvae or puparia per individual beetle as a measure of quality. The fly parasitized only large carabids (,15 mm body length); the lengths of fly puparia reached 7.4,10.8 mm during development in beetle abdomens, and larger hosts are likely essential. Of the 18 large carabid species collected in this study, we chose two, Carabus maiyasanus Bates and Leptocarabus procerulus (Bates), because they were large and abundant (87% of total catch). The two carabids had different phonologies; C. maiyasanus was abundant from spring to summer, and its abundance dropped sharply in autumn, while L. procerulus was abundant in autumn and rare from spring to summer except July. Parasitism was observed in all the months from May to November except June, and adult flies eclosed more than once a year (in early summer, late summer, and mid-autumn), indicating that the species is multivoltine. Host quality of L. procerulus was higher than that of C. maiyasanus. Carabus maiyasanus was mainly used as a host from spring to summer, and L. procerulus was used in autumn. Thus, adult beetles of one or both species are available over most of spring, summer, and autumn, allowing population persistence of this fly species over time. [source] Biology of Anagrus atomus (Hymenoptera: Mymaridae), an egg parasitoid of the grape leafhopper Arboridia kermanshah (Homoptera: Cicadellidae)ENTOMOLOGICAL SCIENCE, Issue 3 2004Shahram HESAMI Abstract Biology, morphology and oviposition behavior of Anagrus atomus (Linnaeus), an egg parasitoid of the grape leafhopper Arboridia kermanshah Dlabola in Isfahan, Iran, were investigated. Adults were smaller than those so far reported from other regions. Females continuously drummed on plant surfaces with their antennae to search for host eggs. Parasitoid eggs hatched 2,3 days after oviposition, and A. atomus had two larval instars. First instar larvae were sacciform and immobile. Second instar larvae appeared 4 days after oviposition and were very active, and doubled their body length. The prepupal and pupal stages lasted for 1 and 5,6 days, respectively. Adult emergence began 16 days after oviposition, and peaked on day 17. [source] Effects of the estrogen agonist 17,-estradiol and antagonist tamoxifen in a partial life-cycle assay with zebrafish (Danio rerio)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2007Leo T. M. van der Ven Abstract A partial life-cycle assay (PLC) with zebrafish (Danio rerio) was conducted to identify endocrine-disrupting effects of 17,-estradiol (E2) and tamoxifen (TMX) as reference for estrogen agonist and antagonist activity. Adult zebrafish were exposed for 21 d and offspring for another 42 d, allowing differentiation of gonads in control animals. The assessed end points included reproductive variables (egg production, fertilization, and hatching), gonad differentiation of juveniles, histopathology, and vitellogenin (VTG) expression. With E2, the most sensitive end points were feminization of offspring (at 0.1 nM) and increased VTG production in males (at 0.32 nM). At 1 nM, decreased F1 survival, increased F1 body length and weight, VTG-related edema and kidney lesions, and inhibited spermatogenesis were observed. Oocyte atresia occurred at even higher concentrations. Exposure to TMX resulted in specific effects at an intermediate test concentration (87 nM), including oocyte atresia with granulosa cell transformation and disturbed spermatogenesis (asynchrony within cysts). In F1, decreased hatching, survival, and body weight and length as well as decreased feminization were observed. Decreased vitellogenesis and egg production in females and clustering of Leydig cells in males occurred at higher concentrations. Toxicological profiles of estrogen agonists and antagonists are complex and specific; a valid and refined characterization of endocrine activity of field samples therefore can be obtained only by using a varied set of end points, including histology, as applied in the presented PLC. Evaluation of only a single end point can easily produce under- or overestimation of the actual hazard. [source] Intraclonal variability in Daphnia acetylcholinesterase activity: The implications for its applicability as a biomarkerENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Liane Biehl Printes Abstract The relationship between individual growth and acetylcholinesterase (AChE) activity was evaluated for Daphnia magna. Analysis on the influence of two different culture media on baseline AChE activity was performed with Daphnia similis. The results indicated an inverse relationship between D. magna body length and AChE activity. An increase in total protein, which was not proportional to an increase in the rate of the substrate hydrolysis (, absorbance/min), seems to be the reason for this inverse size versus AChE activity relationship. Therefore, toxicants such as phenobarbital, which affect protein and size but not AChE activity directly, have an overall affect on AChE activity. In contrast, the AChE inhibitor parathion altered AChE activity but not protein. Culture medium also had a significant affect on AChE activity in D. similis. Changes in total protein seem to be the main reason for the variations in baseline AChE activity in Daphnia observed in the different evaluations performed in this work. Therefore, AChE activity in Daphnia must be interpreted carefully, and variations related to changes in total protein must be taken into account when applying this enzyme as a biomarker in biological monitoring. [source] Body Dimensions of Infants Exposed to Antiepileptic Drugs In Utero: Observations Spanning 25 YearsEPILEPSIA, Issue 7 2000K. Wide Summary: Purpose: To investigate the influence of maternal antiepileptic drug (AED) treatment on pregnancy duration, birth weight, body length, head circumference, and intrauterine growth in infants exposed in utero to antiepileptic drugs in Sweden between 1973,1997, with 963 singleton infants. Methods: Data collected from (a) 1973,1981 (record linkage between a hospital discharge register and a medical birth register); (b) 1984,1995 (prospectively collected information in one defined catchment area with two delivery hospitals); and (c) 1995,1997 (medical birth register data). Observed numbers of infants below a defined size for body measurements compared with expected numbers calculated from all births in Sweden after stratification for year of birth, maternal age, parity, and education or smoking habits in early pregnancy. Standard deviation scores estimated with same stratification procedures. Results: Fraction of monotherapy exposures increased from ,40% to ,90% from 1973 to 1997. Significantly increased numbers of infants with small body measurements found in exposed group. Negative influence on body dimensions decreased over time. More marked effects found in infants exposed to polytherapy. In monotherapy, only infants exposed to carbamazepine consistently showed reduction in body dimensions. Significant effect on gestational age in girls and on number of small for gestational age (<2 SD) in boys. Conclusions: Polytherapy with antiepileptic drugs and negative influence on body dimensions decreased. In monotherapy, only carbamazepine has a negative influence on body dimensions in this study. [source] Male Mate Choice in the Guppy (Poecilia reticulata): Do Males Prefer Larger Females as Mates?ETHOLOGY, Issue 2 2004Emily J. E. Herdman Although females are the choosier sex in most species, male mate choice is expected to occur under certain conditions. Theoretically, males should prefer larger females as mates in species where female fecundity increases with body size. However, any fecundity-related benefits accruing to a male that has mated with a large female may be offset by an associated fitness cost of shared paternity if large females are more likely to be multiply mated than smaller females in nature. We tested the above hypothesis and assumption using the Trinidadian guppy (Poecilia reticulata) by behaviourally testing for male mate choice in the laboratory and by ascertaining (with the use of microsatellite DNA genotyping) patterns of male paternity in wild-caught females. We observed significant positive relationships between female body length and fecundity (brood size) and between body length and level of multiple paternity in the broods of females collected in the Quaré River, Trinidad. In laboratory tests, a preference for the larger of two simultaneously-presented virgin females was clearly expressed only when males were exposed to the full range of natural stimuli from the females, but not when they were limited to visual stimuli alone. However, as suggested by our multiple paternity data, males that choose to mate with large females may incur a larger potential cost of sperm competition and shared paternity compared with males that mate with smaller females on average. Our results thus suggest that male guppies originating from the Quaré River possess mating preferences for relatively large females, but that such preferences are expressed only when males can accurately assess the mating status of encountered females that differ in body size. [source] Female Preferences for Call Traits and Male Mating Success in the Neotropical Frog Physalaemus enesefaeETHOLOGY, Issue 2 2003Zaida Tárano Female preferences for male call traits may affect male mating success and the evolution of exaggerated secondary sexual traits. We used phonotaxis experiments to examine female preferences in the frog Physalaemus enesefae in relation to variation in male call duration, dominant frequency, intercall interval and amplitude (dB SPL). Females preferred long calls, low and average dominant frequency calls, short intercall intervals and more intense calls. We compared the patterns of female preferences with those of acoustic variation among males to test the prediction that properties with low within-male variation are associated with stabilizing or weakly directional female preferences, whereas properties with high within-male variation are associated with directional preferences. Females had weakly directional preferences for the dominant frequency of the call and strongly directional preferences for call duration and call rate. We also determined whether the temporal relationship between calls influenced preferences based on the dominant frequency of the call. Preferences for low-frequency over high-frequency calls disappeared when calls partially overlapped. Females preferred the leading call regardless of its dominant frequency. We also investigated mating patterns in the field. There was size-assortative mating, as male and female body sizes snout-vent length (SVL) were positively correlated. In addition, differences in the frequency distributions of body length (SVL) between mated and unmated males approached significance; lower SVL classes were underrepresented among mated males. These patterns may reflect female preferences for lower dominant frequency calls, as there is a negative correlation between male mass and the dominant frequency of the call. [source] EMPIRICAL EVIDENCE FOR AN OPTIMAL BODY SIZE IN SNAKESEVOLUTION, Issue 2 2003Scott M. Boback Abstract The concept of optimal size has been invoked to explain patterns in body size of terrestrial mammals. However, the generality of this phenomenon has not been tested with similarly complete data from other taxonomic groups. In this study we describe three statistical patterns of body size in snakes, all of which indicate an optimal length of 1.0 m. First, a distribution of largest body lengths of 618 snake species had a single mode at 1.0 m. Second, we found a positive relationship between the size of the largest member of an island snake assemblage and island area and a negative relationship between the size of the smallest member of an island snake assemblage and island area. Best-fit lines through these data cross at a point corresponding to 1.0 m in body length, the presumed optimal size for a one-species island. Third, mainland snake species smaller than 1.0 m become larger on islands whereas those larger than 1.0 m become smaller on islands. The observation that all three analyses converge on a common body size is concordant with patterns observed in mammals and partial analyses of four other disparate animal clades. Because snakes differ so strikingly from mammals (ectotherms, gape-limited predators, elongate body shape) the concordant patterns of these two groups provide strong evidence for the evolution of an optimal body size within independent monophyletic groups. However, snakes differ from other taxonomic groups that have been studied in exhibiting a body size distribution that is not obviously skewed in either direction. We suggest that idiosyncratic features of the natural history of ectotherms allow relatively unconstrained distributions of body size whereas physiological limitations of endotherms constrain distributions of body size to a right skew. [source] COMPARATIVE PHYLOGENETIC ANALYSIS OF THE EVOLUTION OF SEMELPARITY AND LIFE HISTORY IN SALMONID FISHESEVOLUTION, Issue 5 2002Bernard J. Crespi Abstract The selective pressures involved in the evolution of semelparity and its associated life-history traits are largely unknown. We used species-level analyses, independent contrasts, and reconstruction of ancestral states to study the evolution of body length, fecundity, egg weight, gonadosomatic index, and parity (semelparity vs. degree of iteroparity) in females of 12 species of salmonid fishes. According to both species-level analysis and independent contrasts analysis, body length was positively correlated with fecundity, egg weight, and gonadosomatic index, and semelparous species exhibited a significantly steeper slope for the regression of egg weight on body length than did iteroparous species. Percent repeat breeding (degree of iteroparity) was negatively correlated with gonadosomatic index using independent contrasts analysis. Semelparous species had significantly larger eggs by species-level analysis, and the egg weight contrast for the branch on which semelparity was inferred to have originated was significantly larger than the other egg weight contrasts, corresponding to a remarkable increase in egg weight. Reconstruction of ancestral states showed that egg weight and body length apparently increased with the origin of semelparity, but fecundity and gonadosomatic index remained more or less constant or decreased. Thus, the strong evolutionary linkages between body size, fecundity, and gonadosomatic index were broken during the transition from iteroparity to semelparity. These findings suggest that long-distance migrations, which increase adult mortality between breeding episodes, may have been necessary for the origin of semelparity in Pacific salmon, but that increased egg weight, leading to increased juvenile survivorship, was crucial in driving the transition. Our analyses support the life-history hypotheses that a lower degree of repeat breeding is linked to higher reproductive investment per breeding episode, and that semelparity evolves under a combination of relatively high juvenile survivorship and relatively low adult survivorship. [source] Testing hypotheses about fecundity, body size and maternal condition in fishesFISH AND FISHERIES, Issue 2 2004Marten A. Koops Abstract Recent research suggests that maternal condition positively influences the number of eggs spawned in fishes. These studies commonly choose a priori to use body length rather than weight as an explanatory variable of offspring production, even though weight is usually the better predictor of fecundity. We are concerned that consistent exclusion of body weight as a predictor of egg production inflates the variance in fecundity attributable to maternal condition. By analysing data on three populations of Atlantic cod (Gadus morhua, Gadidae) and 10 populations of brook trout (Salvelinus fontinalis, Salmonidae), we illustrate the need for a statistically defensible method of model selection to distinguish the effects of maternal condition on egg production from the effects of body size alone. Forward stepwise regression and null model analyses reveal how length-based regressions can significantly over-estimate correlations between condition and fecundity, leading us to conclude that the effect of condition on egg productivity may not be as ubiquitous or as biologically important as previously thought. Our work underscores the need for greater statistical clarity in analyses of the effects of maternal condition on reproductive productivity in fishes. [source] The effects of kin and familiarity on interactions between fishFISH AND FISHERIES, Issue 4 2003Ashley J W Ward Abstract Fish have been shown to discriminate between individuals on very general bases such as species, body length and colour. More recently, evidence has been accumulating from a number of species that relatedness and familiarity may be extremely important in mediating a range of interactions between individual fish. Studies have shown that fish are able to recognize kin and/or familiars, and that this ability potentially conveys significant benefits, including increased inclusive fitness, reduced inbreeding costs, reduced competition and enhanced antipredator behaviour. Here, we review the literature and consider future directions and applications for this research. [source] Emigration patterns among trout, Salmo trutta (L.), kelts and smolts through spillways in a hydroelectric damFISHERIES MANAGEMENT & ECOLOGY, Issue 5-6 2008M. KRAABØL Abstract, The emigration patterns among radio-tagged trout, Salmo trutta L., kelts (n = 41, total length: 60,90 cm) and smolts [n = 27, total body length (BL): 22,30 cm] in the regulated River Gudbrandsdalslågen, south-east Norway, were studied by investigating the influence of sex (kelts) and BL (kelts and smolts) on the timing of emigration. In total, 49% of the kelts emigrated towards the hydroelectric dam shortly after spawning, whilst 51% over-wintered. Female kelts were five times more likely to initiate autumn emigration, and eight times more likely to descend the spillways during the first release of surface water than males. Large individuals of both sexes descended earlier than smaller individuals. Larger smolts were more likely to descend during the first release of surface water than smaller smolts. To safeguard the emigration of iteroparous trout kelts and smolts, the spillways should release surface water both in autumn and spring to avoid selective forces during emigration through spillways. [source] Prespawning migratory behaviour and spawning success of sea-ranched Atlantic salmon, Salmo salar L., in the River Gudenaa, DenmarkFISHERIES MANAGEMENT & ECOLOGY, Issue 5 2000K. Aarestrup The migratory behaviour of sea-ranched Atlantic salmon, Salmo salar L., was analysed by radio-telemetry in the River Gudenaa, Denmark. The main objectives were to: (1) estimate mortality of returning adults through the fjord; (2) observe rate of progression and migratory pattern in the fjord and river; and (3) record whether spawning occurs in the river. Forty-two returning salmon (19 males and 23 females of total body length from 60,97 cm) reared and released as smolts, were caught and equipped with external radio transmitters in the outer estuary of the River Gudenaa in 1994 and 1995. Of the tagged salmon, 18 (43%) were caught in the estuary, four (10%) were not recorded after release and 20 (47%) entered the river. The mean rate of progression through the fjord was 7.6 km d,1 (range 1.4,18.2) in 1994 and 5.4 km d,1 (range 1.6,17.1) in 1995. Eleven salmon were alive at the onset of the spawning period. Eight were retrieved dead from the river during or after the spawning period; four with empty gonads assumed to be successful spawners, and four with intact gonads. In 1994, unsuccessful spawners (found dead with intact gonads) entered the river earlier and had a longer total migration distance in the river compared to successful spawners. This suggests that spawning success of sea-ranched salmon is associated with time of river entry and river migration length. [source] Functional diversity of crustacean zooplankton communities: towards a trait-based classificationFRESHWATER BIOLOGY, Issue 5 2007ALLAIN J. BARNETT Summary 1. While studies of phytoplankton and terrestrial plant communities have increasingly emphasised the use of functional traits in ecological research, few have yet to apply this approach to zooplankton communities. 2. This study reviews laboratory and observational studies on zooplankton feeding and life history and provides a series of functional trait tables for the North American freshwater zooplankton. Qualitative and quantitative trait tables highlight areas where data were more scarce and point to which types of studies could fill in gaps in our knowledge of zooplankton niches. 3. Data were most complete for the Cladocera across most traits, while feeding information for cyclopoids was most sparse. Qualitative data that distinguished congeneric species were lacking for most groups. 4. A regional community dendrogram for common north-eastern North American zooplankton species was generated and shows that taxonomic differences between species do not capture fully functional differences based on the traits of body length, habitat, trophic group and feeding type. 5. The data collected here, combined with readily measurable species attributes, can be used to generate a multivariate measure of the functional niche of each species found in a community. Armed with this information, functional relationships that are useful for ecological studies of lake ecosystems can be more easily conducted. [source] Trading safety for food: evidence from gut contents in roach and bleak captured at different distances offshore from their daytime littoral refugeFRESHWATER BIOLOGY, Issue 5 2006Z. MACIEJ GLIWICZ Summary 1. Regular diel habitat shifts in roach were detected by hydro-acoustics in five moderately eutrophic, stratifying (maximum depth 24,27 m) and approximately circular lakes (of surface area 15, 75, 125, 300 and 900 ha and diameters 250, 600, 1000, 1700 and 2600 m) in north-eastern Poland in the years 1998,2000, when the lakes were free of smelt and other typical offshore planktivores, and their offshore areas were completely free of fish during the day. 2. The diel change in roach distribution was shown to assume a similar pattern in each lake: fish migrated from a daytime littoral refuge towards the centre of the lake at dusk, and returned to the littoral refuge at dawn. After sunset, fish gradually dispersed offshore until they covered the entire lake area in each of the three smaller lakes. In each of the two larger lakes, only small numbers of fish were seen in the central area at night, implying that the centre of the lake retained high food availability throughout the summer. 3. Inshore,offshore gradients in zooplankton prey density, body size, and numbers of eggs per clutch were weak or undetectable in the two smallest lakes, but strong and persistent in the three larger lakes, with Daphnia densities 5,30 times as high and body length 1.2,1.5 times as great in the central area as inshore. 4. The likely increase in the potential predation risk with distance from the littoral daytime refuge was found to be compensated by increased food gains in those fish which moved offshore at dusk to feed within a short time window, when light intensity was lower to make the risk reduced, but still high enough to see zooplankton prey. The benefit because of increased prey acquisition was greatest in the centre of the largest lake (at 1300 m from the shore), as revealed from gut inspections of roach and bleak trawl-sampled at different distances from the edge of the reed belt, and seen as a gradual, order-of-magnitude increase in the volume of food in the foregut, The food volume against distance-from-shore regression was highly significant on each of the four sampling dates in the largest lake, in spite of the wide variability of food volume in individual fish. [source] Thermal adaptation of Arctic charr: experimental studies of growth in eleven charr populations from Sweden, Norway and BritainFRESHWATER BIOLOGY, Issue 2 2005S. LARSSON Summary 1. Experimental growth data for Arctic charr (Salvelinus alpinus L.), all fed on excess rations, from 11 European watercourses between 54 and 70°N were analysed and fitted to a new general growth model for fish. The model was validated by comparing its predictions with the growth rate of charr in the wild. 2. Growth performance varied among populations, mainly because of variation in the maximum growth potential, whereas the thermal response curves were similar. The estimated lower and upper temperatures for growth varied between ,1.7 to 5.3 and 20.8,23.2 °C, respectively, while maximum growth occurred between 14.4 and 17.2 °C. 3. There was no geographical or climatic trend in growth performance among populations and therefore no indication of thermal adaptation. The growth potential of charr from different populations correlated positively with fish body length at maturity and maximum weight in the wild. Charr from populations including large piscivorous fish had higher growth rates under standardised conditions than those from populations feeding on zoobenthos or zooplankton. Therefore, the adaptive variation in growth potential was related to life-history characteristics and diet, rather than to thermal conditions. [source] Effects of experimentally induced cyanobacterial blooms on crustacean zooplankton communitiesFRESHWATER BIOLOGY, Issue 2 2003Anas Ghadouani SUMMARY 1.,Large in situ enclosures were used to study the effects of experimentally induced cyanobacterial blooms on zooplankton communities. A combination of N and P was added to shallow (2 m) and deep enclosures (5 m) with the goal of reducing the TN : TP ratio to a low level (,5 : 1) to promote cyanobacterial growth. After nutrient additions, high biomass of cyanobacteria developed rapidly in shallow enclosures reaching levels only observed during bloom events in eutrophic lakes. 2.,In the shallow enclosures, particulate phosphorus (PP) was on average 35% higher in comparison with deep enclosures, suggesting that depth plays a key role in P uptake by algae. Phytoplankton communities in both deep and shallow enclosures were dominated by three cyanobacteria species ,Aphanizomenon flos-aquae, Anabaena flos-aquae and Microcystis aeruginosa, which accounted for up to 70% of total phytoplankton biomass. However, the absolute biomass of the three species was much higher in shallow enclosures, especially Aphanizomenon flos-aquae. The three cyanobacteria species responded in contrasting ways to nutrient manipulation because of their different physiology. 3.,Standardised concentrations of the hepatotoxic microcystin-LR increased as a result of nutrient manipulations by a factor of four in the treated enclosures. Increased biomass of inedible and toxin producing cyanobacteria was associated with a decline in Daphnia pulicaria biomass caused by a reduction in the number of individuals with a body length of >1 mm. Zooplankton biomass did not decline at moderate cyanobacteria biomass, but when cyanobacteria reached high biomass large cladocerans were reduced. 4.,Our results demonstrate that zooplankton communities can be negatively affected by cyanobacterial blooms and therefore the potential to use herbivory to reduce algal blooms in such eutrophic lakes appears limited. [source] Reproductive traits of stream-dwelling brown trout Salmo trutta in contrasting neighbouring rivers of central SpainFRESHWATER BIOLOGY, Issue 8 2002G. G. NICOLA 1.,Reproductive traits were studied in seven wild populations of resident brown trout in Spain. We examined whether growth, and certain environmental conditions such as water temperature or food abundance, could explain interpopulation variation in the reproductive characters. 2.,The results indicated that nearby populations subjected to a wide variation in environmental conditions exhibited a similar reproductive performance. 3.,Age distributions and sex ratios were not significantly different among populations. Age ranged from 0+ to 4+ years but the populations were dominated by the 0+ to 2+ groups. In all rivers females matured at age 2+ as opposed to age 1+ and 2+ for males. Mean length at the end of the growth period differed significantly among populations. However, annual growth rate was similar among rivers and was not significantly correlated with either biomass of the benthos or water temperature during the growth season. 4.,Reproductive effort, body condition, fecundity and egg size did not correlate significantly with either the abundance of benthic invertebrates or water temperature. Once the effect of body length on both egg size and number was removed, a significant negative correlation was found between these two traits among populations. [source] Interpreting the smells of predation: how alarm cues and kairomones induce different prey defencesFUNCTIONAL ECOLOGY, Issue 6 2009Nancy M. Schoeppner Summary 1.,For phenotypically plastic organisms to produce phenotypes that are well matched to their environment, they must acquire information about their environment. For inducible defences, cues from damaged prey and cues from predators both have the potential to provide important information, yet we know little about the relative importance of these separate sources of information for behavioural and morphological defences. We also do not know the point during a predation event at which kairomones are produced, i.e. whether they are produced constitutively, during prey attack or during prey digestion. 2.,We exposed leopard frog tadpoles (Rana pipiens) to nine predator cue treatments involving several combinations of cues from damaged conspecifics or heterospecifics, starved predators, predators only chewing prey, predators only digesting prey or predators chewing and digesting prey. 3.,We quantified two behavioural defences. Tadpole hiding behaviour was induced only by cues from crushed tadpoles. Reduced tadpole activity was induced only by cues from predators digesting tadpoles or predators chewing + digesting tadpoles. 4.,We also quantified tadpole mass and two size-adjusted morphological traits that are known to be phenotypically plastic. Mass was unaffected by the cue treatments. Relative body length was affected (i.e. there were differences among some treatments), but none of the treatments significantly differed from the no-predator control. Relative tail depth was affected by the treatments and deeper tails were induced only when tadpoles were exposed to cues from predators digesting tadpoles or cues from predators chewing + digesting tadpoles. 5.,These results demonstrate that some prey species can discriminate among a diverse set of potential cues from heterospecific prey, conspecific prey and predators. Moreover, the results illustrate that the cues responsible for the full suite of behavioural and morphological defences are not induced by tadpole crushing nor can they be induced by generalized digestive chemicals produced when predators digest their prey. Instead, both prey damage and predator digestion of conspecific tissues appear to be important for communicating predatory risk to phenotypically plastic anuran prey. Importantly, the production of chemical cues by predators may be unavoidable and prey have evolved the ability to eavesdrop on these signals. [source] State-dependent fertility in pinnipeds: contrasting capital and income breedersFUNCTIONAL ECOLOGY, Issue 5 2000I. L. Boyd Abstract 1.,The study tested the hypothesis that the occurrence of pregnancy in mammals that are capital breeders will be most closely related to state variables that are indices of food stores. Income breeders would not be expected to have the same relationship. 2.,The study examined the relationships between mass, time of year, age and body length with the occurrence of pregnancy in three species of pinniped. This included two capital breeders (Crabeater Seal, Lobodon carcinophagus Hombron & Jacquinot, and Grey Seal, Halichoerus grypus Fabricius) and one income breeder (Antarctic Fur Seal, Arctocephalus gazella Peters). Multiple logistic regression analysis was used to examine the relationships and the interactions between the different state variables. 3.,In both the capital breeders the state variables used in the study explained approximately twice the amount of variability (55% compared with 25%) in the occurrence of pregnancy than in the income breeder. Mass was the dominant state variable among both the capital breeders whereas in the income breeder mass was less important both relative to other state variables and in absolute terms. The results support the conclusion that the occurrence of pregnancy in capital breeders is more sensitive to body reserves than it is in income breeders. 4.,The results also support the conclusion that life histories are the end result of a variety of functional responses to different state variables that have differing degrees of influence. In particular a size-structured approach to studies of population dynamics in pinnipeds may be a more informative way of predicting population responses to environmental variability than the more traditional age-structured approach. [source] | ||||||||||||||||||||||||||||||||||||||||