Increasing Body Size Research Articles

Diurnal and Sex Ratio Flight Activity of Rare Cavity-Dweller Eucnemis capucina Ahrens, 1812 (Coleoptera: Eucnemidae) in Lowland Deciduous Forest: Case Study from Czech Republic

The cavity-dwelling saproxylic beetles are very poorly studied because of their hidden way of life, and they are threatened by forest management. Eucnemis capucina is a rare and sporadic species in all of its distribution area. This species is associated with old hollow trees, which may be why it is on the red lists of many European countries; however, this association could be an indicator of diverse forest structure. We monitored diurnal and seasonal flight activity with intercept flight traps installed on massive ash trees during three seasons. The observed peak of seasonal activity was in May and June. Contrasting most eucnemids, E. capucina is clearly a daytime species, with flight activity between 8:00 and 20:00 and peaking at 14:20. The peak of flight activity is the same for both sexes, but males are more active at the beginning and end of the flight period compared to females. An unequal sex ratio 1.91:1 (F:M) of captured individuals was recorded. The increasing body size of females affected the number of eggs in the body of adult females. The average potential fecundity of a female was 54 eggs, 10 eggs per 1 mm of female body length. The eggs themselves were oval in shape and only the length of the eggs correlated to the body size of the females; the width did not change with body size and did not correlate with egg length, either. We also confirmed that even a single hollow tree can host high numbers or whole populations of rare species and, thus, have a high conservation value. Our study may help better understand the biology of cavity-dwelling beetles and their active life.

Effect of iodine concentration and body size on iodine subtraction in virtual non-contrast imaging: A phantom study

IntroductionDual-energy computed tomography (DECT) can generate virtual non-contrast (VNC) images. Herein, we sought to improve the accuracy of VNC images by identifying the optimal slope of contrast media (SCM) for VNC-image generation based on the iodine concentration and subject's body size. MethodsWe used DECT to scan a multi-energy phantom including four iodine concentration rods (15, 10, 5, and 2 mg/mL), and 240 VNC images (eight SCM ranging from 0.49 to 0.56 × three body sizes × ten scans) that were generated by three-material decomposition. The CT number of each iodine and solid water rod part was measured in each VNC image. The difference in the CT number between the iodine and the solid water rod part was calculated and compared using paired t-test or repeated measures ANOVA. ResultsThe SCM that achieved an absolute value of the difference in CT number of <5.0 Hounsfield units (HU) for all body sizes simultaneously was greater at lower iodine concentration (SCM of 0.5, 0.51, and 0.53 at 10, 5, and 2 mg/mL iodine, respectively). At an iodine concentration of 15 mg/mL, no SCM achieved an absolute difference of <5.0 HU in CT number for all body sizes simultaneously. At all iodine concentrations, the SCM achieving the minimal difference in the CT number increased with the increase in body size. ConclusionBy adjusting the SCM according to the iodine concentration and body size, it is possible to generate VNC images with an accuracy of <5.0 HU. Implications for practiceImproving the accuracy of VNC images minimizing incomplete iodine subtraction would make it possible to replace true non-contrast (TNC) images with VNC images and reduce the radiation dose.

Does the Evolution of Ontogenetic Niche Shifts Favor Species Coexistence? An empirical test in Trinidadian streams.

A major question in ecology is how often competing species evolve to reduce competitive interactions and facilitate coexistence. One untested route for a reduction in competitive interactions is through ontogenetic changes in the trophic niche of one or more of the interacting species. In such cases, theory predicts that two species can coexist if the weaker competitor changes its resource niche to a greater degree with increased body size than the superior competitor. We tested this prediction using stable isotopes that yield information about the trophic position (δ15 N) and carbon source (δ13 C) of two coexisting fish species: Trinidadian guppies (Poecilia reticulata) and killifish (Rivulus hartii). We examined fish from locations representing three natural community types: 1) where killifish and guppies live with predators; 2) where killifish and guppies live without predators; and 3) where killifish are the only fish species. We also examined killifish from communities in which we had introduced guppies, providing a temporal sequence of the community changes following the transition from a killifish only to a killifish-guppy community. We found that killifish, which are the weaker competitor, had a much larger ontogenetic niche shift in trophic position than guppies in the community where competition is most intense (killifish-guppy only). This result is consistent with theory for size-structured populations, which predicts that these results should lead to stable coexistence of the two species. Comparisons with other communities containing guppies, killifish and predators and ones where killifish live by themselves revealed that these results are caused primarily by a loss of ontogenetic niche changes in guppies, even though they are the stronger competitor. Comparisons of these natural communities with communities in which guppies were translocated into sites containing only killifish showed that the experimental communities were intermediate between the natural killifish-guppy community and the killifish-guppy-predator community, suggesting contemporary evolution in these ontogenetic trophic differences. These results provide comparative evidence for ontogenetic niche shifts in contributing to species coexistence and comparative and experimental evidence for evolutionary or plastic changes in ontogenetic niche shifts following the formation of new communities.

Type 1 vomeronasal receptor expression in juvenile and adult lungfish olfactory organ

Lungfish are the most closely related fish to tetrapods. The olfactory organ of lungfish contains lamellae and abundant recesses at the base of lamellae. Based on the ultrastructural and histochemical characteristics, the lamellar olfactory epithelium (OE), covering the surface of lamellae, and the recess epithelium, contained in the recesses, are thought to correspond to the OE of teleosts and the vomeronasal organ (VNO) of tetrapods. With increasing body size, the recesses increase in number and distribution range in the olfactory organ. In tetrapods, the expression of olfactory receptors is different between the OE and VNO; for instance, the type 1 vomeronasal receptor (V1R) is expressed only in the OE in amphibians and mainly in the VNO in mammals. We recently reported that V1R-expressing cells are contained mainly in the lamellar OE but also rarely in the recess epithelium in the olfactory organ of lungfish of approximately 30 cm body length. However, it is unclear whether the distribution of V1R-expressing cells in the olfactory organ varies during development. In this study, we compared the expression of V1Rs in the olfactory organs between juveniles and adults of the African lungfish Protopterus aethiopicus and South American lungfish, Lepidosiren paradoxa. The density of V1R-expressing cells was higher in the lamellae than in the recesses in all specimens evaluated, and this pattern was more pronounced in juveniles than adults. In addition, the juveniles showed a higher density of V1R-expressing cells in the lamellae compared with the adults. Our results imply that differences in lifestyle between juveniles and adults are related to differences in the density of V1R-expressing cells in the lamellae of lungfish.

Age-Related and Seasonal Dynamics of Hemocyte Population in the Mussel &lt;i&gt;Crenomytilus grayanus&lt;/i&gt; (Dunker, 1853)

The cellular composition of the hemolymph of the mussel Crenomytilus grayanus is represented by hemoblasts, hyalinocytes, basophilic, neutrophilic and acidophilic granulocytes with a significant predominance of the latter. With the age of the mollusk, the average values of the size and granularity of hemocytes increased due to accumulation of granulocytes in the hemolymph (up to 100% of all cells) and their mature highly differentiated acidophilic forms (up to 99% of all cells); this indicates a decrease in the rate of renewal of the cell population. During the autumn period of sexual inertia, the number of cells in the hemolymph of mussels decreased with increasing age of mollusks but without any correlation with the shell size. However, in summer, during the spawning period, the concentration of hemocytes either did not change or increased with increasing body size, directly correlating with the number of young basophilic granulocytes. This correlation may indicate either a relationship between the number of hemocytes and the ability of mussels to reach large sizes, or a higher potency in aged mussels for emergency mobilization of the immune system in the summer season through rapid replenishment of the pool of circulating cells with subsequent redistribution of young and mature cell forms between hemolymph and the internal organs.

Associations of childhood-to-adulthood body size trajectories and genetic susceptibility with the risks of osteoarthritis: a population-based cohort study of UK Biobank data

BackgroundLarge adulthood body size was associated with increased risk of osteoarthritis. We aimed to examine the association between body size trajectories from childhood to adulthood and potential interactions with genetic susceptibility on osteoarthritis risk. MethodsWe included participants from the UK Biobank aged 38–73 years in 2006–10. Childhood body size information was collected by questionnaire. Adulthood BMI was assessed and transformed into three categories (<25 kg/m2 for normal, 25–29·9 kg/m2 for overweight, and >30 kg/m2 for obesity). A Cox proportional hazards regression model was applied to assess the association between body size trajectories and osteoarthritis incidence. Osteoarthritis-related polygenic risk score (PRS) was constructed to evaluate its interactions with body size trajectories on osteoarthritis risk. FindingsFor the 466 292 participants included, we identified nine body size trajectories [thinner to normal (11·6%), overweight (17·2%), or obesity (26·9%); average to normal (11·8%), overweight (16·2%), or obesity (23·7%); and plumper to normal (12·3%), overweight (16·2%), or obesity (23·6%)]. Compared with individuals in the average-to-normal group, all other trajectory groups had higher risks of osteoarthritis, after adjustment for demographic, social-economic and lifestyle covariates (hazard ratios [HRs] 1·05–2·41; all p<0·01). Among them, thinner-to-obesity (HR 2·41; 95% CI 2·23–2·49) had the most prominent association with increased osteoarthritis risk. A high PRS was significantly associated with an increased risk of osteoarthritis (1·14; 1·11–1·16), whereas no interaction between childhood-to-adulthood body size trajectories and PRS on osteoarthritis risks was observed. The population attributable fraction suggested that body size towards normal in adulthood could eliminate osteoarthritis cases by 18·67% for thinner-to-overweight to 38·74% for plumper-to-obesity. InterpretationAverage-to-normal body size seems to be the healthiest childhood-to-adulthood trajectory for osteoarthritis risk, whereas a trajectory of increased body size from thinner to obesity has the highest risk for osteoarthritis. These associations are independent of osteoarthritis genetic susceptibility. FundingThe National Natural Science Foundation of China (32000925) and Guangzhou Science and Technology Program (202002030481).

Phenotypic Plasticity in Juvenile Frogs That Experienced Predation Pressure as Tadpoles Does Not Alter Their Locomotory Performance

Anuran species can respond to environmental changes via phenotypic plasticity, which can also result in ecological impacts across the life history of such species. We investigated the effects of predation pressure (i.e., the non-consumption effect) from the dragonfly larva (Anax parthenope) on the phenotypical change of tadpoles into juvenile frogs (specifically the black-spotted pond frog, Pelophylax nigromaculatus), and also analyzed the impact of morphological changes on locomotory performance after metamorphosis. The experiments on predator impact were conducted in the laboratory. Body length, weight, development timing, and metamorphosis timing in the presence of dragonfly nymphs were measured in both tadpoles and juvenile frogs. The body and tail shapes of the tadpoles, as well as the skeletal shape of the juvenile frogs, were analyzed using landmark-based geometric morphometrics. Furthermore, the locomotory performance of the juvenile frogs was tested by measuring their jumping and swimming speeds. Tadpoles that had grown with predators possessed smaller bodies, deeper tail fins, and slower development rates, and they waited longer periods of time before commencing metamorphosis. Having said this, however, the effect of predator cues on the body length and weight of juvenile frogs was not found to be significant. These juvenile frogs possessed longer limbs and narrower skulls, with subtle morphological changes in the pelvis and ilium, but there was no subsequent difference in their swimming and jumping speeds. Our results showed that the changes in anatomical traits that can affect locomotor performance are so subtle that they do not affect the jumping or swimming speeds. Therefore, we support the view that these morphological changes are thus by-products of an altered tadpole period, rather than an adaptive response to predator-escape ability or to post-metamorphosis life history. On the other hand, delayed metamorphosis, without an increase in body size, may still be disadvantageous to the reproduction, growth, and survival of frogs in their life history following metamorphosis.

Functional space analyses reveal the function and evolution of the most bizarre theropod manual unguals

Maniraptoran dinosaurs include the ancestors of birds, and most used their hands for grasping and in flight, but early-branching maniraptorans had extraordinary claws of mysterious function. Alvarezsauroids had short, strong arms and hands with a stout, rock-pick-like, single functional finger. Therizinosaurians had elongate fingers with slender and sickle-like unguals, sometimes over one metre long. Here we develop a comprehensive methodological framework to investigate what the functions of these most bizarre bony claws are and how they formed. Our analysis includes finite element analysis and a newly established functional-space analysis and also involves shape and size effects in an assessment of function and evolution. We find a distinct functional divergence among manual unguals of early-branching maniraptorans, and we identify a complex relationship between their structural strength, morphological specialisations, and size changes. Our analysis reveals that efficient digging capabilities only emerged in late-branching alvarezsauroid forelimbs, rejecting the hypothesis of functional vestigial structures like T. rex. Our results also support the statement that most therizinosaurians were herbivores. However, the bizarre, huge Therizinosaurus had sickle-like unguals of such length that no mechanical function has been identified; we suggest they were decorative and lengthened by peramorphic growth linked to increased body size.

Role of sexual and natural selection in the evolution of sexual size dimorphism in primates

AbstractIn mammals, the dominant theory proposes that sexual size dimorphism evolved by sexual selection in a polygynous reproductive scenario. Natural selection is an alternative hypothesis where dimorphism represents an adaptation to ecological pressures. I tested evolutionary models based on sexual and natural selection processes using phylogenetic confirmatory path analyses. I employed data for 225 primate species in terms of their diel activity, body mass, sexual size dimorphism, level of sociality, and level of polygyny. The model that received the most support from path analyses was a mixed model in which dimorphism evolved after an increase in body size that resulted from a response to an ecological pressure, i.e., a change from nocturnal to diurnal habits, with a lesser role of polygyny. Phylogenetic path analysis suggests that natural selection has played an important role in the evolution of sexual size dimorphism in primates.

Environmental drivers of body size in North American bats

Abstract Bergmann's rule—which posits that larger animals live in colder areas—is thought to influence variation in body size within species across space and time, but evidence for this claim is mixed. We used Bayesian hierarchical models to test four competing hypotheses for spatiotemporal variation in body size within 20 bat species across North America: (1) the heat conservation hypothesis, which posits that increased body size facilitates body heat conservation (and which is the traditional explanation for the mechanism underlying Bergmann's rule); (2) the heat mortality hypothesis, which posits that increased body size increases susceptibility to acute heat stress; (3) the resource availability hypothesis, which posits that increased body size is enabled in areas with more abundant food; and (4) the starvation resistance hypothesis, which posits that increased body size reduces susceptibility to starvation during acute food shortages. Spatial variation in body mass was most consistently (and negatively) correlated with mean annual temperature, supporting the heat conservation hypothesis. Across time, variation in body mass was most consistently (and positively) correlated with net primary productivity, supporting the resource availability hypothesis. Climate change could influence body size in animals through both changes in mean annual temperature and resource availability. Rapid reductions in body size associated with increasing temperatures have occurred in short‐lived, fecund species, but such reductions will be obscured by changes in resource availability in longer‐lived, less fecund species. Read the free Plain Language Summary for this article on the Journal blog.

Candidate genes potentially involved in molting and body size reduction in the male of the horned gall aphid, Schlechtendalia chinensis.

In general, insects grow (increase in body size) through molting. To the opposite, the body size of the males of the horned gall aphid, Schlechtendalia chinensis, gets smaller after molting and as they age. To understand the molecular bases of this rare phenomenon, transcriptomes were generated from 1-5days old male and the data were analyzed via a weighted gene co-expression network analysis (WGCNA). A total of 15 partitioned modules with different topological overlaps were obtained, and four modules were identified as highly significant for male body length (p < 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis suggested that a portion of genes in the four modules are likely involved in autophagy and apoptosis. In addition, a total of 40 hub genes were obtained in the four modules, and among them eight genes were highly expressed in males compared to individuals of other generations of S. chinensis. These eight genes were associated with autophagy and apoptosis. Our results reveal the unique negative growth phenomenon in male S. chinensis after molting, and also suggest that the male S. chinensis with no ability to feed probably decompose their own substances via autophagy and apoptosis to provide energy for life activities such as germ cell development.

Changes in Cortical Composition during Gyrification in the Developing Brain

Background and Hypothesis: Abnormal brain folding has been implicated in neurodivergent conditions such as schizophrenia and autism, yet the mechanical and biological processes responsible for this process are not well understood. One current hypothesis is that cortex growth outpaces growth of the underlying white matter to drive mechanical buckling. However, mechanical stresses, such as those resulting from buckling, can also influence cellular behavior. In this study, we hypothesized that mechanical stresses from cortical folding influence processes of biological growth within the cortex, such as dendrite arborization within the neuropil and neuronal differentiation.&#x0D; Methods: To quantify change in cell body size and neuropil over the period of cortical folding, sections of the developing ferret brain (postnatal days 20, 26, 32, and 38) were stained with FluoroNissl dye, imaged with confocal microscopy, and analyzed using Fiji software. Change in percent neuropil, cell area, cell density, and overall length were quantified at upper, middle, and lower thirds of the cortex to assess the influence of bending stresses within gyri and sulci during development.&#x0D; Results: Preliminary analysis revealed a substantial increase in neuropil over time in the upper layers of the cortex. However, gyral regions expected to experience mechanical tension and increased expansion did not exhibit the hypothesized differences in neuropil or cell size. Though there was an overall increase in neuropil volume fraction and cell body size over time, throughout all layers of the cortex, these factors only accounted for roughly 2/3 of the physical growth quantified throughout these cortical layers.&#x0D; Potential Impact: Findings indicate that neuropil and cell body expansion are insufficient to fully explain the growth observed during cortical folding. These results highlight a potential role for alternative cellular processes, such as the migration of other cell types into the cortex, to induce cortical growth and folding in gyrencephalic species.

Magneto-nanofluid flow in cylinder-embedded discretely heated-cooled annular thermal systems: Conjugate heat transfer and thermodynamic irreversibility

The present work investigates magnetohydrodynamics-driven thermal-fluid flow characterization in cylinder-embedded annular thermal systems subjected to peripheral differential heating. It explores Al2O3/water nanofluid flow-associated heat transfer and entropy generation in the presence of a magnetic field and a conducting cylindrical obstruction (block). The consequence of various obstruction sizes on thermo-fluid flow behavior is also analyzed. The transport equations are handled by a finite element-based solver. The thermal-flow analysis is carried out for the relevant vital parameters such as Rayleigh number (Ra), Hartmann number (Ha), magnetic field orientation (γ), and obstruction size. Through the investigation, it is found that Nusselt number (Nu) is greatest when the internal conducting block size is the least. It can thus be inferred that flow circulation plays a dominant role in determining the Nu value. Heat flow dynamics described by the heatlines, as well as flow structure examined by the streamlines, are found to vary depending upon the obstruction size, and the field orientation (γ). Furthermore, the total entropy generation figures out that when the buoyant forces within the thermal systems are low, the entropy generation is uniform along the periphery; however, when the buoyant forces take a significantly higher value, the contours of entropy generation are seen to be more concentrated near the discretely heated and cooled walls. It is seen that if the inner conducting body size increases, the overall entropy production significantly increases. Finally, a generalized single mathematical correlation is developed for both heat transfer and entropy generation. This thermal system configuration has practical relevance and the present findings could enrich the understanding of pre-existing concepts in the area of thermal systems pertaining to effective heat-exchanging devices.

Scaling patterns of body plans differ among squirrel ecotypes.

Body size is often hypothesized to facilitate or constrain morphological diversity in the cranial, appendicular, and axial skeletons. However, how overall body shape scales with body size (i.e., body shape allometry) and whether these scaling patterns differ between ecological groups remains poorly investigated. Here, we test whether and how the relationships between body shape, body size, and limb lengths differ among species with different locomotor specializations, and describe the underlying morphological components that contribute to body shape evolution among squirrel (Sciuridae) ecotypes. We quantified the body size and shape of 87 squirrel species from osteological specimens held at museum collections. Using phylogenetic comparative methods, we first found that body shape and its underlying morphological components scale allometrically with body size, but these allometric patterns differ among squirrel ecotypes: chipmunks and gliding squirrels exhibited more elongate bodies with increasing body sizes whereas ground squirrels exhibited more robust bodies with increasing body size. Second, we found that only ground squirrels exhibit a relationship between forelimb length and body shape, where more elongate species exhibit relatively shorter forelimbs. Third, we found that the relative length of the ribs and elongation or shortening of the thoracic region contributes the most to body shape evolution across squirrels. Overall, our work contributes to the growing understanding of mammalian body shape evolution and how it is influenced by body size and locomotor ecology, in this case from robust subterranean to gracile gliding squirrels.

Trophic Positions of Sympatric Copepods across the Subpolar Front of the East Sea during Spring: A Stable Isotope Approach

We investigated the trophic relationship between particulate organic matter (POM) and sympatric copepods within the epipelagic zone (~200 m depth) in the East Sea during spring based on stable isotope analysis (SIA). The SIA indicated that interspecific differences in the prey size and vertical segregation of feeding migration range among copepods may promote niche partitioning among sympatric copepods in each region of the subpolar front (SPF). Additionally, our results showed remarkable differences in the copepod community structure and resource utilization across the SPF. The south region of the East Sea showed higher species richness of copepods than the north region, while copepods that fed mainly on POM in the surface and subsurface chlorophyll maximum layers showed smaller body sizes in the south region. These results revealed that the food chain between primary producers and higher trophic levels was longer in the south region than in the north region. Additionally, δ13C and δ15N values of copepods increased gradually with the body size increase whereas δ15N values in the north region showed the reverse trend. Latter results could be attributed to the consumption of deep-layer POM in small copepods. Therefore, we suggest that northward shifts in the distribution of copepods under global warming may decrease energy efficiency in the pelagic ecosystem of the East Sea.

Age and Feeding Habits of Caml Grenadier Macrourus caml in Cosmonauts Sea

Macrourus caml is a main by-catch in the Southern Ocean fishery and a main prey species of Antarctic toothfish Dissostichus mawsoni; it plays an important role in the Southern Ocean ecosystem. In this study, age estimation and stomach content analysis were conducted by using samples collected from the Cosmonauts Sea in 2021. The main objectives of this study were to estimate the age and diet of grenadier M. caml and explore the feeding habits of M. caml. Morphological analysis and molecular identification were conducted to determine the diet of M. caml in this study. Stomach content analysis showed that M. caml mainly fed on Malacostraca, Sagittoidea, Cnidaria and Algae, with the Malacostraca accounting for over 50%. The feeding habits of male and female M. caml were similar. The age of M. caml ranged from 9 to 19 years. Additionally, with the increase of body size, the proportion of Cnidaria was decreasing whereas the proportion of Malacostraca was increasing. The results would provide a reference for exploring the trophic level of M. caml and the food web in the Cosmonauts Sea.

Gnawing pressure led to the expansion of JAZ genes in angiosperms

A long-standing problem in evolutionary biology is why some populations differentiate into many species while the majority do not. Angiosperms is an excellent group for investigating this problem because their diversity is unevenly distributed in space and phylogeny. Plant hormone participates in growth, development and defense. However, jasmonic acid (JA) was the only hormone response to bites. We first searched jasmonate ZIM-domain (JAZ), AUXIN/INDOLE ACETIC ACID (IAA / aux), PYR/PYL/RCAR (PYL), DELLA, and SUPPRESSOR OF MAX2 1-like (SMAX) in 272 plant species. We found the gene number change trends were consistent with origination rates and species numbers of angiosperms. So, 26 representative species were selected as an example for further analysis. The results showed JAZ had experienced two lineage-specific gene expansion events in angiosperms, which coincided with increases in mammalian body size and dental diversity. The proliferation of large herbivores as a results of mammalian prosperity after dinosaur extinction may be related to angiosperm evolution and bursting. The proliferation of large herbivores as the result of mammalian prosperity after the extinction of the dinosaurs was related to angiosperm evolution and bursting. Overall, our study uncovered a previously unknown co-evolution mechanism in terrestrial plants exposed to extreme environmental conditions.

Using a novel biologging approach to assess how different handling practices influence the post-release behaviour of Northern Pike across a wide range of body sizes

There is a growing body of research focused on how angled fish respond to catch-and-release (C&amp;R). However, most of those studies do not span a wide range of body sizes for the targeted species. Physical injury and physiological responses to C&amp;R can be size-dependent, and methods used for landing fish of different sizes vary. As such, studying the response to C&amp;R across a range of fish sizes may help inform best practices that improve outcomes for released fish. Northern Pike (Esox lucius) widely ranges in body size. Anglers may land them by hand, cradle, or net, and they are often released voluntarily or to comply with regulations. We angled 25 Northern Pike (total length 620–1030 mm) from one population and recorded fight, handling, and unhooking times across landing methods (i.e., hand, cradle, net). Prior to release, a pop-off biologging package was temporarily affixed to each fish to monitor locomotor activity, depth, and water temperature during a 12-h period post-release to understand how the interaction of landing method and body size influenced post-release behaviour and short-term fate. Fight and handling time increased with increasing body size. Northern Pike landed with a cradle or net had shorter fight times but longer handling times, compared to fish landed by hand. Post-release locomotor activity was greater for larger fish and those landed with a net. Fish &lt;775mm and landed by hand had greater locomotor activity than fish landed with a net or cradle, while fish &gt;775mm landed by hand had reduced locomotor activity compared to fish landed with a net. There was no post-release mortality observed. Collectively, anglers should use a net for Northern Pike &gt;775 mm to avoid long fight times and reduce post-release exhaustion, but also attempt to reduce the extent of handling associated with fish landed by net.

Effects of spirulina (Arthrospira maxima) on teratogenicity and diclofenac-induced oxidative damage in Xenopus laevis

Diclofenac (DCF) is a medication that is highly consumed and eliminated worldwide; it is constantly detected in the environment (primarily in water) and resists conventional degradation processes. It was included in the European Union watch list for the water framework. There are no regulations for this compound in Mexico. Therefore, this study evaluated the protective effect antioxidant activity of spirulina (Arthrospira maxima) against DCF-induced toxicity in Xenopus laevis at early life stages. X. laevis oocytes were exposed at the medium blastula stage for 96 h to three different mixtures: DCF+S 2 (149 µg L-1 DCF plus 2 mg L-1 spirulina), DCF+S 4 (149 µg L-1 DCF plus 4 mg L-1 spirulina), DCF+S 10 (149 µg L-1 DCF plus 10 mg L-1 spirulina). Other groups of oocytes were also exposed to DCF 149 µg L-1 and a control group. The mortality and malformation rate, growth, lipid peroxidation, and antioxidant enzymatic activity (superoxide dismutase and catalase) were determined. Spirulina at 4 and 10 mg L-1 reduced DCF-induced mortality by 80% and reduced malformations in severity and frequency. The abnormalities were malformations of the eye, tail, notochord, intestine, and rectum. All spirulina exposure groups showed an increase in total body size compared to those exposed to DCF.

Reproductive biology, length-weight relationship and diet of co-occurring butterfly rays, Gymnura poecilura and Gymnura zonura, in Malaysian waters.

Recent IUCN assessments had resulted in up listing of the status of butterfly rays due to concerns of overfishing, but inadequate biological understanding of these rays prevents meaningful conservation and management measures. Therefore, this study was undertaken to address knowledge gaps in the reproductive biology and diet of longtail butterfly ray (Gymnura poecilura) and zone tail butterfly ray (Gymnura zonura) in Malaysian waters. From surveys of landing sites and fish markets from years 2017 to 2022, size (disc width, DW), weight and maturity were recorded, and stomachs were collected from 94 G. poecilura (N=39 females and 55 males) and 20 G. zonura (N=10 females and 10 males) specimens. The length-weight relationships were significantly different between sexes for G. poecilura. The size at maturity (DW50) was estimated to be 476.0 mm (females), 385.0 mm (males) for G. poecilura and 442.0 mm (combined) for G. zonura. The number of embryos ranged from 1 to 6, and the embryo size was between 73.90 to 130.44 mm DW. Dietary analysis of stomach contents revealed that fish prey was dominant in both G. poecilura [94.4% Index of Relative Importance (IRI)] and G. zonura (100% IRI). Ontogenetic shift was seen in G. poecilura that fed on more variety of prey items, including shrimps, squids and crabs with an increase in body size. Both species co-occur all along coastal Malaysia although G. zonura is rarely encountered from fisheries surveys along the Strait of Malacca. Given similar habitat associations and dietary habits, G. poecilura may be able to outcompete G. zonura across their shared habitat range. The validity of G. japonica and G. micrura records in Malaysia remains questionable and requires future investigation.