Function Of Body Length Research Articles

Broadband target strength of arabesque greenling, Pacific sand lance, and pointhead flounder

Abstract Measurement of target strength (TS) is important for estimating the abundance of species using fisheries acoustics. However, most researchers have only used a limited number of representative frequencies for acoustic measurements of fish without a swim bladder (bladderless fish). Here, we measured the broadband TS of three bladderless fish species, arabesque greenling (Pleurogrammus azonus), Pacific sand lance (Ammodytes personatus), and pointhead flounder (Cleisthenes pinetorum), using two broadband echosounders. TS measurements were conducted in a seawater tank over frequency ranges of 45–90 and 80–120 kHz using a tether method. Higher TS and directivity were observed at higher frequencies than at lower frequencies for pointhead flounder and arabesque greenling. However, the TS for Pacific sand lance was relatively flat over the measured frequency spectra. Additionally, the TS of pointhead flounder and Pacific sand lance could be expressed as a function of body length and the TS of arabesque greenling could be expressed as a function of body length and frequency, which could be used in fish species discriminations and size estimations.

Acoustic Target Strength of the Endangered Chinese Sturgeon (Acipenser sinensis) by Ex Situ Measurements and Theoretical Calculations

The Chinese sturgeon, Acipenser sinensis, is a large anadromous and highly endangered protected species. The assessment of its breeding population in the Yangtze River is critically important for effective management and population preservation. Currently, hydroacoustic methods have been widely used to study the adult sturgeons in the river, whereas the acoustic target strength (TS) characteristics of the species have not been studied. In this study, the TS of Chinese sturgeon was carefully evaluated both by ex situ measurements and theoretical calculations. Six Chinese sturgeons (Body Length (BL): 74.0−92.6 cm) were measured by a 199 kHz split echosounder in a 10-m deep net cage. The computed tomography of a Chinese sturgeon (BL: 110.0 cm) was conducted and the Kirchhoff ray mode (KRM) method was used to estimate the theoretical TS. As a result, the mean ex situ TS range of the six specimens was from −26.9 to −31.4 dB, which was very close to the KRM estimation (~1 dB difference). Then, the KRM method was used to predict the TS of Chinese sturgeon as a function of BL in six frequencies commonly used in freshwater environments and to estimate the TS of a representative adult Chinese sturgeon (250 cm) as a function of frequency and tilt angle. This study can provide a good basis for future hydroacoustic studies on the critically endangered Chinese sturgeon.

Comparative study on morphological and biological characters of two sand lances

Morphological and biological characters of Ammodytes personatus and A.hexaperus from the waters nearby Soya in Japan were measured.The results indicated that there was some variance between the two species based on the function of body length and body weight and gonadosomatic index(GSI).One-way ANOVA results showed that though there was great(70%) overlap in vertebra numbers,difference between the two Ammodytes species in vertebra numbers was extremely significant(P0.01).The otolith angle was firstly used for identification of the two species.The average otolith angle of A.personatus [(86.8 0.4) ] was significantly lower than that of A.hexaperus [(93.0 0.5) ](P0.05).The exact discriminant rate(84.3% on average) was high based on otolith angle to identify the two species.It was suggested that otolith angle could be used for identifying A.personatus and A.hexaperus efficiently.

Modelling the migration of post-smolt Atlantic salmon (Salmo salar) in the Northeast Atlantic

Abstract Mork, K. A., Gilbey, J., Hansen, L. P., Jensen, A. J., Jacobsen, J. A., Holm, M., Holst, J. C., Ó Maoiléidigh, N., Vikebø, F., McGinnity, P., Melle, W., Thomas, K., Verspoor, E., and Wennevik, V. 2012. Modelling the migration of post-smolt Atlantic salmon (Salmo salar) in the Northeast Atlantic. – ICES Journal of Marine Science, 69: 1616–1624. The migration of post-smolt Atlantic salmon (Salmo salar) during their first 4 months at sea in the Northeast Atlantic was simulated using an individual-based model that combined a particle-tracking scheme with growth and behaviour routines. The migration was decomposed into both passive pelagic drift with the surface currents, provided by an ocean model, and active horizontal swimming behaviour. The active swimming direction was aligned with the surface current. Swimming speed was a function of body length and calculated from recaptured tagged salmon. Releases of particles in the model were made to the west of Ireland and to the southwest of Norway. The modelled post-smolt distributions were compared with the observed distributions, and a sensitivity analysis using different swimming speeds was performed. The strength and direction of the flow can transport the post-smolts towards areas with favourable feeding conditions. However, in some areas, the direction of migration was sensitive to interannual changes in the windforcing, leading the post-smolts to areas with a different environment and prey. Inclusion in the swimming behaviour of a preference for water with higher temperature and salinity displaced the northward migration more offshore, away from coastal areas.

Depth selectivity and spatial distribution of juvenile lake sturgeon in a large, fragmented river

Summary Lake sturgeon are considered imperilled across much of their range where rehabilitation efforts have been employed to enhance recovery. Habitat requirements are not known for all life stages of lake sturgeon, especially the juvenile stage. Juvenile lake sturgeon can be important in assessing effectiveness of rehabilitation efforts and therefore life history requirements for this stage is important. The objectives of this study were to determine if juvenile lake sturgeon within the Ottawa River, Canada has a depth preference; if so, to determine if depth selectivity was a function of body length; and finally, to determine if spatial structuring exists for juvenile lake sturgeon within reach type (i.e. impounded vs unimpounded reaches). A depth stratified, index netting program selective to juvenile lake sturgeon was conducted in the Ottawa River, Canada from 2008–2010. Overall, a total of 192 juvenile lake sturgeon were sampled. A Bayesian approach was used to analyze the data including logistic regression, Poisson regression and generalized linear model. The probability of capturing a juvenile lake sturgeon in a net and their relative abundance was greatest as the 12–20 m depth stratum and lowest at 35–50 m depth stratum in both impounded and unimpounded river reaches. Lake sturgeon mean total length was smallest at shallowest depth stratum (1–3 m) and greatest in the deepest depth stratum (50–75 m). For spatial segregation, mean total length of lake sturgeon was significantly smaller in the lower reach of the three contiguous, unimpounded reaches whereas the trend was opposite in impounded reaches where the smallest lake sturgeon were sampled in the upper third of the river reach. This study therefore identified areas where the probability of capturing a juvenile lake sturgeon is the greatest and where to best expend efforts through a stratified random sample study design when conducting effectiveness monitoring of any restoration or management actions.

Species- and size-specific variability of mercury concentrations in four commercially important finfish and their prey from the northwest Atlantic

Total mercury was analyzed as a function of body length, season, and diet in four commercially and recreationally important marine fish, bluefish (Pomatomus saltatrix), goosefish (Lophius americanus), silver hake (Merluccius bilinearis), and summer flounder (Paralichthys dentatus), collected from continental shelf waters of the northwest Atlantic Ocean. Mercury levels in the dorsal muscle tissue of 115 individuals ranged from 0.006 to 1.217μg/g (wet weight) and varied significantly among species. The relationship between predator length and mercury concentration was linear for bluefish and summer flounder, while mercury levels increased with size at an exponential rate for silver hake and goosefish. Mercury burdens were the highest overall in bluefish, but increased with size at the greatest rate in silver hake. Seasonal differences were detected for bluefish and goosefish with mercury levels peaking during summer and spring, respectively. Prey mercury burdens and predator foraging habits are discussed as the primary factors influencing mercury accumulation.

Effect of body length and temperature on the crawling speed of Protophormia terraenovae larvae (Robineau-Desvoidy) ( Diptera Calliphoridae)

This work investigates variation in the crawling speed of Protophormia terraenovae larvae (Robineau-Desvoidy) (Diptera Calliphoridae) as a function of body length and ambient temperature. A video-tracking system was used to follow the movement of larvae in an experimental arena, and to estimate their average crawling speed. Recordings were carried out at various temperatures using larvae of different developmental stages. As temperature increased, the larvae crawled at a faster speed. Furthermore, speed increased as a function of body length. We present a general allometric relationship to express the average crawling speed of larvae as a combined function of temperature and body length, expressed in the following equation: speed ( cm / min ) = 5.45 × log [ length ( mm ) ] + 0.66 × temperature ( ∘ C ) - 12.8 These results are particularly useful in forensic entomology for estimating the time that elapsed following the larva's departure from the corpse. This information can provide more accuracy for post-mortem interval estimations and a better comprehension of larvae behaviour and displacement.

Age effects and size effects in the ears of gekkonomorph lizards: inner ear

Audiograms have indicated greater auditory sensitivity in larger than in smaller geckos; part of this difference, interspecifically and intraspecifically, is explained by middle-ear proportions. To investigate the contribution of the inner ear to the variation in sensitivity, we examined it in museum specimens representing 11 species and three subfamilies. We measured papilla basilaris length, and, when intact, the saccular otoconial mass. Papilla length approximated 1% of rostrum-anus length in large geckos but 2% in small geckos; in some species some inter-aural difference was indicated. Over the lumped material, relative papilla length varied as a function of body length, with highly significant correlation. Similar relations prevailed within each subfamily. However, intraspecifically the correlation of papilla basilaris length with animal size was usually nonsignificant. Hair cell populations assessed from SEM photographs were larger in the larger species but intraspecifically did not relate to an individual’s size. Hence interspecifically, the dependence of auditory sensitivity on animal size seems supported by inner-ear differences but intraspecifically this relation derives only from the middle ear. Otoconial mass, as measured by its volume, was correlated with animal length both interspecifically and intraspecifically.

Reproductive biology of the female Japanese mantis shrimp Oratosquilla oratoria (Stomatopoda) in relation to changes in the seasonal pattern of larval occurrence in Tokyo Bay, Japan

: The reproductive traits and the monthly larval abundance of the mantis shrimp Oratosquilla oratoria were investigated in Tokyo Bay, Japan, in 2002. The goal of the study was to elucidate the cause of changes in the monthly pattern of larval abundance from the 1980s to the 1990s as these changes relate to variation in the stock size of the adult shrimp. Oogenesis was divided into 10 stages by histological observation. The developmental stage of oocytes in an individual's ovary was synchronous, suggesting that almost all the oocytes in an ovary are spawned at the same time. The size at first maturity was estimated to be 7 ≤ body length (BL) < 8 cm. Fecundity was expressed as a function of BL, ranging from 19 300 eggs for 8 cm BL to 92 100 eggs for 14 cm BL. Small female shrimps (<10 cm BL) spawned around August. Most large female shrimps (≥10 cm BL) spawned around May, and some large female shrimps also spawned until September. Although most large female shrimps spawned in spring, the larval abundance was low before July and high from August onwards. The results suggest that a substantial decrease in the stock size of large individuals causes the low larval abundance before July.

Refuge use in sticklebacks as a function of body length and group size

A change in anti–predator strategy from hiding to grouping outside a refuge was observed in large three–spined sticklebacks. No such change in strategy was seen in small fish. The body–length dependence of this strategy change is discussed in the context of metabolic constraints.

Refuge use in sticklebacks as a function of body length and group size

A change in anti–predator strategy from hiding to grouping outside a refuge was observed in large three–spined sticklebacks. No such change in strategy was seen in small fish. The body–length dependence of this strategy change is discussed in the context of metabolic constraints.

Mating behaviours of Daphnia pulicaria, a cyclic parthenogen: comparisons with copepods

The pre–and post–contact mating behaviours ofDaphnia pulicariaare investigated by direct observations of vertical distributions, swimming behaviours and male–female interactions. Analysis of vertical distributions in a 1 m deep, thermally stratified migration chamber reveals that females were always located in the upper layer of the water column but males exhibited a bimodal depth distribution, in which an individual's depth was a function of body length and water temperature. The observed distributions of males may be the result of several interacting pressures; predation avoidance, life–history optimization, and avoidance of assortative mating. Male swimming behaviour was faster and orthogonal to that of females, which is in agreement with the predictions of encounter–rate maximization models. Video recordings of males and females interacting in a 1–litre vessel showed that males both pursued and contacted other males more often than females. Thus, there was no evidence thatDaphniaare able to use water–borne chemical signals to locate and identify potential mates. However, the average duration of male–female contacts (13.8 s) was much longer than those between males (1.6 s), suggesting that males can determine the sex of contacted individuals.Daphniamating behaviour is significantly more complex than previously acknowledged. In contrast to the conventional view ofDaphniamales swimming more–or–less randomly and mating with any individual encountered, they exhibit behaviours which increase the potential of mating with females while reducing the risk of predation. Several male behaviours, such as ‘scanning’ and the performance of area–restricted spirals upon encounter, are similar to those reported for some copepods and may be common to zooplankton that lack sophisticated chemosensory abilities. The possibility thatDaphniamay also be able to assess such important female attributes as species and reproductive status is discussed.

Cannibalism on eggs by dark chub, Zacco temmincki (Temminck &amp; Schlegel) (Cyprinidae)

During spawning male dark chub, Zacco temmincki (Temminck &amp; Schlegel), buried eggs by stirring up the river bed with their anal fins. No parental care was shown for eggs after spawning. Many satellites (both males and females) preyed upon eggs at the instant of spawning. The number of eggs produced is a function of body length [log10E=−0.273+3.519log10S, where E is the number of eggs and S is standard length (cm)]. From the size distribution of females that spawned during a reproductive season, the total number of spawning sites used and mean number of eggs per spawning site, at least 97.1% eggs were estimated to be consumed by cannibalism. This marked cannibalism resulted from a lack of parental care and the presence of many satellites produced by the polygynous mating system.

Effects of suspended clay on Daphnia body growth and fitness

SUMMARY1. Suspended sediments often reduce the abundance, fitness, and feeding rates of planktonic cladocerans. This paper examines the effect of suspended clay particles on the body growth and life‐history parameters of Daphnia ambigua. Cohorts were exposed to zero or 50mgl−1 suspended clay (particle size &lt;2μm). Individuals exposed to clay had significantly lower body lengths at a given age than individuals in the control cohort. Parameters for the von Bertalanffy body growth equation were calculated for each individual; the asymptotic maximum body length (lmax) was reduced, but the growth rate constant (k) was unaffected, by the presence of suspended clay. Body length at reproductive maturity was lower in the presence of suspended clay; this may be an adaptive response and is similar to the response of cladocerans to limiting food concentrations.2. Age‐specific survivorship and fecundity were both reduced, and the ages of maturity and first reproduction were both increased, in the presence of suspended clay. The overall effect of these demographic changes was a 70% decline in the net reproductive rate (Ro), a measure of fitness.3. Suspended clay affected the relationship between body length and fecundity. Animals of a given length produced fewer eggs in the presence of suspended clay. In addition, there was a significant interaction in the effects of body length and clay on brood size: the slope of the regression line of brood size as a function of body length was lower in the presence of clay. This interaction has also been observed in limiting food concentrations, and may be caused by reductions in body length at maturity in low food or high clay environments.4. The similarity between the effects of limiting food concentrations and suspended clay on Daphnia body growth, survivorship, fecundity, and brood size makes sense, given previous observations showing that suspended clay reduces the feeding rate of D. ambigua by up to 70% due to mechanical interference with feeding behaviours.

OIL FLOWERS AND OIL BEES: FURTHER EVIDENCE FOR POLLINATOR ADAPTATION.

We examined foreleg length and body size variation in two species of oil-collecting bees (Rediviva; Melittidae) in southern Africa. Oil-collecting bees harvest oil from host flowers by rubbing their forelegs against oil-secreting trichomes. Significant differences in foreleg length occur among populations of both species. Rediviva "pallidula" populations vary significantly in mean foreleg length (11.34 ± 0.42 mm to 12.67 ± 0.36 mm), but not in body length (10.59 ± 0.74 to 10.80 ± 0.64), and foreleg length and body size are not significantly correlated. Instead, foreleg variation appears to be a function of host plant spur length. Ninety-two percent of the variance in foreleg length of R. "pallidula" is explained by mean Diascia spur length. Rediviva rufocincta populations vary significantly in mean foreleg length (10.12 ± 0.70 mm to 12.34 ± 0.68 mm) and in body length (9.03 ± 0.26 mm to 10.56 ± 0.24 mm). Foreleg length scales allometrically with body size in this species as 90.5% of the variance in foreleg length can be explained as a function of body length. Body size appears to be constrained by the morphology of the oil-secreting host plant. Both bees collect floral oil with specially modified setae on the tarsi of their forelegs. The length of the disti- + mediotarsus (refered to here as "tarsus") in relation to the entire foreleg is shorter in R. rufocincta and does not increase as rapidly with increasing foreleg length as for R. "pallidula." These differences in variation can be attributed to differences in position of oil within the flowers of the respective host plants. Rediviva "pallidula" collects oil from Diascia species that have the oil deeply situated in narrow floral spurs of varying length, while R. rufocincta collects oil from the broadly saccate flowers of Bowkeria verticillata and B. citrina.

Feeding behaviour and limb morphology of two cladocerans with small intersetular distances

Length-weight relationships, feeding rates, and surface area and morphology of the third and fourth thoracic limbs of Daphnia carinata and Ceriodaphnia quadrangula s.l. were examined. Weight (W) increased between the square and cube of body length (L). W= 7.88 × 10-7 L2.23, W= 1 .7 × 10-6 L2.26 for D. carinata and C. quadrangula s.l., respectively. Both cladocerans had small (&lt;0.3 �m) intersetular distances. Surface areas (A) of limbs 3 and 4 increased as a power function of body length: A = 5.35 × 10-2 L2.0 (D. carinata); A = 1 .22 L1.6 (C. quadrangula s.l.). Reynolds number was &lt; 1; boundary layers surrounding the setules overlapped at beat rates of 5 and 16 cycles s-1. Filtering rates (K) for both species increased with increasing body length according to K = 1 .8 × 10-4 L2.0 (D. carinata) and K = 1.3 × 10-5 L2.2 (C. quadrangula s.1.). K also increased as a power function of limb surface area. Filtering rates on Ankistrodesmus falcatus decreased above cell concentrations of c. 104 cells ml-1. Hourly feeding rates (No. of cells per animal) increased with increasing cell concentration up to the incipient limiting concentrations and thereafter remained relatively stable. Weight-specific feeding rates for D. carinata decreased with increasing body size but for C. quadrangula s.l. remained relatively constant. D. carinata positively selected particles in the size range 4.8-7.0 �m, whereas C. quadrangula s.l. showed no particle preference within the size range 3-12�m. Both cladocerans showed differences in their feeding behaviour when offered a range of phytoplankton species but both fed most efficiently on A. falcatus. Although these cladocerans had limb morphologies that differentiated them from their Northern Hemisphere counterparts, this was not reflected in their feeding behaviour.

Dispersal of the collembolan, Folsomia Candida Willem, as a function of age

The tendency of Folsomia Candida to disperse varies with age. In laboratory experiments, the youngest individuals rarely moved from the release sites in dispersal trays, while the older F. Candida showed a tendency to move into more distant areas. Distance travelled is an approximately linear function of body length, and length is a power function of age in this species. The same linear relationship between dispersal and age was apparent over short (2 h) and long (24 h) dispersal periods. When food was present on the release site, the dispersive behavior of the youngest and the oldest classes was unchanged. However, the presence of food restricted travel of medium-sized springtails, many of which remained in the release site to feed. Since these young adults begin oviposition while still growing at a relatively high rate, their food requirements are higher than younger and older springtails. This change in behavior significantly altered the relationship between size and distance travelled. In natural situations, it is advantageous for the youngest individuals to remain in the area in which they hatched, where ample food and moisture are likely to be found. Because of their greater tendency to disperse, the older individuals spread their eggs over a larger area.

Notes on the Northern Gulf of Mexico Occurrence of Sagitta friderici Ritter-Zahony (Chaetognatha)

The neritic chaetognath Sagitta friderici Ritter-Zahony, 191 1 was identified in plankton samples from the northern Gulf of Mexico in June 1974. Specimens analyzed from two groups of adults ranged from 6 to 13.7 mm long. Meristic values did not appear to be a function of body length except for individuals in the 12.4 to 13.7 mm range that had larger numbers of hooks and teeth. Adults of sagitta friderici and the closely related S. tenuis Conant, 1896 were compared and found to be distinguishable chiefly by (1) the number of ova per unit length of the ovary, and (2) the arrangement of ova within the ovary. The TC values were highly variable and overlapping, thus casting doubt on the taxonomic importance of that characteristic. Sagitta friderici was abundant in inshore continental shelf waters where the salinity and temperature ranged from 24.9 to 33.9 ppt and 23.0 to 30.3’C, respectively. The failure to determine ecological boundaries between S. friderici and S tenuis revealed a need for more intensive sampling in coastal regions of the Gulf of Mexico.

Mitosis in the intact and regenerating planarian Dugesia mediterranea n.sp. I. Mitotic studies during growth, feeding and starvation

AbstractPlanarian neoblasts, the only cell type in this organism endowed with mitotic power, decrease in density as total body volume, total cell number, and length increase. Studies on mitosis show that the neoblast mitotic rate is a function of body length, being lower as the organism increases in length. The cephalo‐caudal distribution of mitotic figures in animals of different sizes shows a change towards a more even distribution of mitosis jointly with a mitotic increase in the caudal regions as length increases. However, in the sagittal and dorso‐ventral axes, the distribution of mitosis is always nonuniform, probably due to the uneven distribution of parenchymal tissue along them.The pharynx of animals in all size groups examined shows no mitotic figures except some near its base. This may suggest for this organ a proximal type of growth with some cell migration.Feeding elicits a very rapid increase in mitosis which lasts for almost a week, whereas long periods of starvation do not cause a significant increase or decrease in the basal mitotic rate. All these results stress the need of looking at the planarian neoblast mainly as a stem or replacement cell of most differentiated cell types and not as a mere “regeneration cell.” The implications of the results obtained for the mechanisms of growth and shrinkage are discussed.

A New Species of the formosus Group of the Lizard Genus Sceloporus

It will be noticed that although the relationship between centrum length and body length is linear one, the relationship between CL/CW and body length is not. Centrum width increases faster than centrum length as body size increases. This is necessary because the width of vertebra determines its resistance to compression stress. The stress that the vertebra must endure is function of body weight. Thus, centrum width is function of body weight, while centrum length is function of body length. It will be recalled that body weight increases faster than body length (WbaLb3). All of the evidence indicates that the holotypic vertebra of Crotalus giganteus is midbody vertebra. Based on relationship between mid-body vertebral length and snake body length derived from examination of four species of Crotalus, the type of C. giganteus came from snake approximately 1.9 meters long. Klauber (1973) gives the maximum known length of C. adamanteus as 2.2 meters. Neill (1961) records a few C. adamanteus received at Ross Allen's Reptile Institute that exceeded 2.1 meters in length. Thus, the largest known specimen of Crotalus giganteus, the holotype (see Auffenberg, 1963), was no larger than some specimens of Recent Crotalus adamanteus. The name Crotalus giganteus Brattstrom should be referred to the synonymy of Crotalus adamanteus Beauvois. ACKNOWLEDGMENTS