The organization of tissues in appendages often affects their mechanical properties and function. In the fish family Labridae, swimming behavior is associated with pectoral fin flexural stiffness and ...morphology, where fins range on a continuum from stiff to relatively flexible fins. Across this diversity, pectoral fin flexural stiffness decreases exponentially along the length of any given fin ray, and ray stiffness decreases along the chord of the fin from the leading to trailing edge. In this study, we examine the morphological properties of fin rays, including the effective modulus in bending (E), second moment of area (I), segmentation, and branching patterns, and their impact on fin ray stiffness. We quantify intrinsic pectoral fin ray stiffness in similarly sized fins of two closely related species that employ fins of divergent mechanics, the flapping Gomphosus varius and the rowing Halichoeres bivittatus. While segmentation patterns and E were similar between species, measurements of I and the number of fin ray branch nodes were greater in G. varius than in H. bivittatus. A multiple regression model found that of these variables, I was always significantly correlated with fin ray flexural stiffness and that variation in I always explained the majority of the variation in flexural stiffness. Thus, while most of the morphological variables quantified in this study correlate with fin ray flexural stiffness, second moment of area is the greatest factor contributing to variation in flexural stiffness. Further, interspecific variation in fin ray branching pattern could be used as a means of tuning the effective stiffness of the fin webbing to differences in swimming behavior and hydrodynamics. The comparison of these results to other systems begins to unveil fundamental morphological features of biological beams and yields insight into the role of mechanical properties in fin deformation for aquatic locomotion.
This study quantifies pectoral fin ray morphology and its relationship to stiffness. Variation in fin ray second moment of area explains the majority of the variation in stiffness, providing insight into the relationship between form and function.
Un total de 326 helmintos parásitos fueron recuperados de 94 especímenes de Halichoeres bivittatus (Pisces: Labridae) en dos sitios de la zona arrecifal en los límites del Parque Nacional Sistema ...Arrecifal Veracruzano, Veracruz, México, el suroeste del Golfo de México: Punta Gorda (n = 51) y Mata de Uva (n = 43). Los peces fueron capturados entre mayo y septiembre de 2001. Cada muestra se analizó a nivel de comunidad componente e infracomunidad. Tres especies de helmintos se localizaron en intestino: Nicolla halichoeri (Digenea) considerándose nuevo registro de localidad, Procamallanus (Spirocamallanus) garnotus (Nematoda) es nuevo registro de hospedero, y las larvas de Tetraphyllidea gen. sp. (Cestoda) fueron los parásitos con mayor prevalencia e intensidad promedio para cada sitio. La riqueza de especies para ambos sitios fue de S = 3 y el índice de diversidad de Shannon-Wiener (Punta Gorda, H´'= 0,42; Mata de Uva, H´'= 0,49) fueron inferiores a los registrados para las comunidades hospedero-parásito de lábridos y de hospederos de la localidad. No hubo correlación entre el número total de especies o el número total de helmintos con respecto a la longitud total o el peso del hospedero. El análisis de las curvas de especies acumuladas para la comunidad componente sugirió, que el inventario de especies de helmintos estaba casi completo para ambos sitios. La abundancia de larvas del céstodo ubica a H. bivittatus como hospedero intermediario del parásito.
Growth rate, longevity, maturity and spawning seasonality were estimated for the endemic Hawaiian hogfish Bodianus albotaeniatus. The sex‐specific von Bertalanffy growth parameters are L∞ = 339 mm ...fork length (LF) and K = 0.66 year−1 for females and L∞ = 417 mm LF and K = 0.33 year−1 for males. The maximum age is 22 years. Histological gonad analysis and the absence of small and young males indicate a monandric protogynous hermaphrodite. Size and age at maturity for combined sexes are L50 = 238 mm LF and A50 = 1.6 years.
Pteragogus trispilus Randall, 2013, previously known as Pteragogus pelycus, is a lessepsian migrant to the eastern Mediterranean Sea. Reporting two specimens, this paper confirms the occurrence of ...the species in Iskenderun Bay (Eastern Mediterranean coast of Turkey) in addition to the previous reports from the Mediterranean coast of Turkey. This report is the first observation for the location and; thus, fills a gap in the distribution range of the species. All measurements and counts as well as morphological and color descriptions of P. trispilus are given in the study.
Changes from coral to macroalgal dominance following disturbances to corals symbolize the global degradation of coral reefs. The development of effective conservation measures depends on ...understanding the causes of such phase shifts. The prevailing view that coral-macroalgal phase shifts commonly occur due to insufficient grazing by fishes is based on correlation with overfishing and inferences from models and small-scale experiments rather than on long-term quantitative field studies of fish communities at affected and resilient sites. Consequently, the specific characteristics of herbivorous fish communities that most promote reef resilience under natural conditions are not known, though this information is critical for identifying vulnerable ecosystems. In this study, 11 years of field surveys recorded the development of the most persistent coral-macroalgal phase shift (>7 years) yet observed on Australia's Great Barrier Reef (GBR). This shift followed extensive coral mortality caused by thermal stress (coral bleaching) and damaging storms. Comparisons with two similar reefs that suffered similar disturbances but recovered relatively rapidly demonstrated that the phase shift occurred despite high abundances of one herbivore functional group (scraping/excavating parrotfishes: Labridae). However, the shift was strongly associated with low fish herbivore diversity and low abundances of algal browsers (predominantly Siganidae) and grazers/detritivores (Acanthuridae), suggesting that one or more of these factors underpin reef resilience and so deserve particular protection. Herbivorous fishes are not harvested on the GBR, and the phase shift was not enhanced by unusually high nutrient levels. This shows that unexploited populations of herbivorous fishes cannot ensure reef resilience even under benign conditions and suggests that reefs could lose resilience under relatively low fishing pressure. Predictions of more severe and widespread coral mortality due to global climate change emphasize the need for more effective identification and protection of ecosystem components that are critical for the prevention of coral reef phase shifts.
In fish, social interactions are commonly accompanied by acoustic signalling. Males have been found to produce sounds in a large range of species, but female sounds have received considerably less ...attention. But even in males, there remain significant taxonomical gaps, e.g. in one of the largest fish families, the wrasses. Here, we investigate sound production in territorial males and females of the corkwing wrasse in a field study in Norway. We complemented an in-depth analysis of the visual and acoustic behavioural repertoire of territorial males by descriptions of female behaviours. Males as well as females produced sounds in courtship and agonistic contexts. We recorded four types of sounds and found significant differences between male and female sound properties. We hereby provide one of the first descriptions of sound production in wrasses and, to our knowledge, the first one to also investigate female sound production. Our study shows that wrasses are an underappreciated family when it comes to sound production. With a repertoire of four different calls, corkwing wrasses are remarkably versatile among fishes. Our results highlight the potential and importance of future research about sound communication in neglected taxa, and in both sexes.
Age structure data is essential for single species stock assessments but length-frequency data can provide complementary information. In south-western Australia, the majority of these data for ...exploited species are derived from line caught fish. However, baited remote underwater stereo-video systems (stereo-BRUVS) surveys have also been found to provide accurate length measurements. Given that line fishing tends to be biased towards larger fish, we predicted that, stereo-BRUVS would yield length-frequency data with a smaller mean length and skewed towards smaller fish than that collected by fisheries-independent line fishing. To assess the biases and selectivity of stereo-BRUVS and line fishing we compared the length-frequencies obtained for three commonly fished species, using a novel application of the Kernel Density Estimate (KDE) method and the established Kolmogorov-Smirnov (KS) test. The shape of the length-frequency distribution obtained for the labrid Choerodon rubescens by stereo-BRUVS and line fishing did not differ significantly, but, as predicted, the mean length estimated from stereo-BRUVS was 17% smaller. Contrary to our predictions, the mean length and shape of the length-frequency distribution for the epinephelid Epinephelides armatus did not differ significantly between line fishing and stereo-BRUVS. For the sparid Pagrus auratus, the length frequency distribution derived from the stereo-BRUVS method was bi-modal, while that from line fishing was uni-modal. However, the location of the first modal length class for P. auratus observed by each sampling method was similar. No differences were found between the results of the KS and KDE tests, however, KDE provided a data-driven method for approximating length-frequency data to a probability function and a useful way of describing and testing any differences between length-frequency samples. This study found the overall size selectivity of line fishing and stereo-BRUVS were unexpectedly similar.
Aim
Compare the distribution and composition of temperate Labridae (wrasse) assemblages on shallow water coastal reefs in South‐Western Australia between 2006 and 2015, after a decade characterized ...by both gradual ocean warming and severe heatwave events.
Location
South‐Western Australia from Port Gregory to the Recherché Archipelago.
Methods
Surveys of Labridae fishes were conducted in 2006 and repeated in 2015 across 112 reefs spanning 2,000 km of coastline, using diver‐operated stereo‐video systems (stereo‐DOVs). We used a hierarchical design with seven regions, four locations in each region, four reef sites in each location and twelve transects in each site.
Results
In 2015, we found an increase in abundance of tropical and subtropical labrid species that were rarely observed in 2006. Three temperate species declined in abundance, which tended to be large and slow growing fish. Twenty‐two labrid species increased in abundance. There was also a discernible poleward shift in 20 of the 25 most abundant and representative labrid species from 2006 to 2015. The labrid community composition was explained predominantly by sea surface temperature (SST), physical reef structure and kelp (Ecklonia radiata) cover.
Main conclusions
Our study reveals that labrid assemblages associated with the shallow water temperate reefs of South‐Western Australia have undergone rapid changes across almost 2,000 km of coastline, with warm‐temperate waters showing the strongest change. However, cool‐temperate waters on the south coast also showed significant changes in the composition of the labrid assemblages. Our findings provide important insights into the effects of warming and habitat loss on warm‐temperate assemblages and the potential trajectory of change for cool‐temperate assemblages under a warmer future.
This study investigated tool use by the graphic tuskfish Choerodon graphicus in New Caledonia. Anvils included rocks, a conical shell, flat dead corals and a concrete mooring. Sixteen tool‐use events ...were observed in 10 h. A tool‐use event often involved more than one anvil (44%). On average, C. graphicus struck prey six times and spent 84 s at an anvil. The only prey items brought to anvils were bivalve and gastropod molluscs. These results provide a foundation for future research on tool use in fishes.
Patterns of reproductive ontogeny in four species of coral reef wrasses (F: Labridae) Hemigymnus melapterus, Hemigymnus fasciatus, Cheilinus fasciatus and Oxycheilinus digramma were investigated. ...Populations of each species were sampled from two island groups of the central Great Barrier Reef (GBR), Australia, and from coral reefs in the central Philippines. These three sampling locations span 30° of latitude. The GBR and Philippine reefs experience biologically significant differences in water temperature, geography and human activity. The studied wrasses are effectively unfished in Australia but heavily fished in the Philippines. Gonad weights, histology and demographic data were obtained across the entire size and age range of H. melapterus, C. fasciatus and O. digramma from all locations. Analysis identified three processes of male recruitment: functional gonochorism and both forms of protogynous hermaphroditism, monandry and diandry. The expression of these distinct sexual ontogenies was locality dependent. Populations of H. melapterus, H. fasciatus, C. fasciatus and O. digramma on the GBR showed consistently uniform patterns of sexual ontogeny, with all species being exclusively monandric. H. melapterus, C. fasciatus and O. digramma in the Philippines displayed complex sexual ontogenies, with all species showing histological evidence of both diandry and functional gonochorism. Reproductive investment in gonadal tissue, and population sex structure, also differed between GBR and Philippine coral reefs. Philippine populations had substantially lower gonado‐somatic indices than populations on the GBR. Nonetheless, Philippine populations matured more rapidly and displayed a protracted timing of sex change over a large size and age range. Thus, mature females appeared earlier and persisted later into ontogeny in the Philippines than on GBR reefs. Protracted timing of sex change on Philippine reefs is likely linked to the presence of primary males in the population, which is known to reduce the strength of selection for mature females to undergo sex change and become male. Hypotheses based on social structure of fish populations, environmental factors and evolutionary history were developed to account for the different patterns of sexual ontogeny in the focal wrasses.
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