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1.
J Aquat Anim Health ; 2024 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-39218786

RESUMEN

OBJECTIVE: The Blackchin Guitarfish Glaucostegus cemiculus is endemic to the Mediterranean Sea and is critically endangered, but relevant routine laboratory data are unavailable. Our objectives were to determine the packed cell volume (PCV), comprehensive serum chemistry analytes, and serum total thyroxine (sTT4) concentration; compare serum albumin and serum globulin concentrations as measured by two different methods; and describe the blood cell morphology of healthy, free-ranging Blackchin Guitarfish. METHODS: Wild Blackchin Guitarfish were captured using a seine net. Blood samples for serum chemistry and hematological analyses were obtained and measured using routine laboratory methods. The fish were tagged and released. RESULT: This study included 43 Blackchin Guitarfish (17 males and 26 females) that were younger than 6 months as estimated based on total length and body weight. The median PCV (n = 23) was 22% (minimum-maximum [min-max] = 15-25%). Median sTT4 (n = 10) measured by chemiluminescence immunoassay was 7.86 nmol/L (min-max = 7.52-9.57 nmol/L). The study included a comprehensive, 25-analyte serum chemistry analysis (e.g., serum iron and unbound and total iron-binding capacity) and a morphological description of all blood cells. Serum electrophoresis (SEP; n = 13) yielded a consistent serum albumin-migrating protein fraction and four globulin fractions. Serum electrophoretograms corroborating these results are presented. CONCLUSION: In Blackchin Guitarfish, the serum albumin-migrating fraction measured by SEP combined with serum total protein concentration yields a much higher albumin concentration compared to that measured by bromocresol green spectrophotometry. The true identity of this albumin-migrating fraction remains to be identified. The analytes' calculated 2.5-97.5% interpercentile intervals should be considered as reference intervals applying to Blackchin Guitarfish of similar age but should be applied cautiously to adult fish.

2.
R Soc Open Sci ; 11(9): 240532, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39233723

RESUMEN

The global decline of shark populations, largely driven by overfishing to supply the shark fin trade, poses a significant threat to marine ecosystems. Southeast Asia, and particularly Singapore, is a key hub for the transit and trade of shark fins that contribute to the exploitation of these apex predators. Through the use of DNA barcoding techniques, this study aimed to determine what species of shark are involved in the Singapore shark fin trade. Fins were collected from markets, dried goods shops and traditional Chinese medicine halls throughout Singapore. In total, DNA was extracted from 684 fins collected in January 2024 and PCR amplification targeted a fragment of the mitochondrial COI gene for species identification. Results revealed fins from 24 species across 16 genera, with 19 species listed on CITES Appendices II, and 16 listed as threatened on the IUCN Red List (critically endangered = 2, endangered = 4, vulnerable = 10). The top five most frequently identified species were Carcharhinus falciformis, Galeorhinus galeus, Rhizoprionodon oligolinx, Sphyrna lewini and Rhizoprionodon acutus. Of these, four are listed on CITES Appendix II and four are listed as threatened on the IUCN Red List.

3.
J Fish Biol ; 2024 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-38986516

RESUMEN

The Rio de Janeiro Marine Aquarium (AquaRio) is the first to successfully maintain and reproduce the spiny butterfly ray (Gymnura altavela), providing unique information about the species' biology. Seven rays were kept in captivity between 2018 and 2023, two captured on the southeastern coast of Brazil and five born in the aquarium. The applied abiotic conditions and nutrition allowed for the survival, growth, and reproduction of these individuals. Growth parameters (asymptotic disk width-DW∞ and growth coefficient-k) were estimated based on the von Bertalanffy model using the Fabens method for males and females separately. The best models estimated DW∞ = 106.47 cm and k = 0.396 for males and DW∞ = 172.2 cm and k = 0.190 for females. Sexual dimorphism was corroborated, with females reaching larger sizes and presenting slower growth rates than males. The estimated k values were higher than those estimated for rays of similar size to G. altavela in the natural environment, probably due to the constant water temperature (around 25.5°C), food abundance, low population density, reduced predation rates, and high water quality in the captive environment. A comparison of the captivity findings with other studies on G. altavela age and growth in the Atlantic and Mediterranean indicates a broad phenotypic plasticity regarding growth. Three G. altavela reproductions were recorded, with size at birth appearing to be a key factor for pup's survival. Behavioral pattern observations associated with reproduction are also described, encompassing chasing and copulation, whereas the species' internal morphology is described through coelomic cavity ultrasound scanning.

4.
Biology (Basel) ; 13(6)2024 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-38927285

RESUMEN

A remarkable new deep-water skate, Leucoraja longirostris n. sp., is described based on eight specimens caught during different expeditions to the southern Madagascar Ridge in the southwestern Indian Ocean. The new species differs from all congeners by its remarkably long and acutely angled snout (horizontal preorbital length 17.2-22.6% TL vs. 8.5-11.9% TL and 4.2-6.1 vs. 1.7-3.5 times orbit length, snout angle 65-85° vs. 90-150°). Furthermore, it is apparently endemic to the Madagascar Ridge, distant from the known distribution areas of all congeners. In addition to L. fullonica and L. pristispina, L. longirostris n. sp. is also the only species with plain dorsal coloration. Furthermore, the new species is the only Leucoraja species with an external clasper component dike and, besides L. wallacei, the only one with four dorsal terminal (dt) cartilages. The shape of the accessory terminal 1 (at1) cartilage with four tips is also unique within the genus. A new approach for the visualization of the clasper characters is introduced based on 3D models of all skeletal and external features. This enables a much easier and much more precise interpretation of every single clasper component, of the entire structure, and, in particular, the relationship between external features and skeletal cartilages. A new English translation of the first diagnosis of Leucoraja is provided, along with a revised generic diagnosis and a key to the species of Leucoraja in the Indian Ocean.

5.
Cretac Res ; 155: 105779, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38799703

RESUMEN

Upper Cretaceous coastal marine deposits are widespread in the Southern Urals with a number of marine vertebrates previously reported from this region. However, previous studies on the vertebrate faunas in this region often lack detailed taxonomic descriptions and illustrations, rendering comparisons to other faunal assemblages difficult. A new diverse vertebrate assemblage comprising cartilaginous and bony fishes, as well as marine reptiles, is described here from the Orenburg region near Akkermanovka (Southern Urals, Russia). Thirty five taxa are identified, including three holocephalans (Elasmodus sp., Ischyodus yanschini, Chimaeroid indet.), two hybodontiform sharks (Meristodonoides sp., cf. Polyacrodus sp.), 17 neoselachians (Paraorthacodus cf. andersoni, Paraorthacodus sp., Synechodus sp., Cederstroemia nilsi, Acrolamna acuminata, Archaeolamna ex gr. kopingensis, Cretalamna sarcoportheta, Cretoxyrhina mantelli, Eostriatolamia segedini, E. venusta, Hispidaspis horridus, H. cf. gigas, Pseudocorax laevis, Pseudoscapanorhynchus compressidens, Scapanorhynchus rhaphiodon, Squalicorax kaupi, Ptychodus rugosus), a holostean (Lepisosteidae indet.), nine teleosts (Protosphyraena sp., Saurodontidae indet., cf. Pachyrhizodus sp., Pachyrhizodontidae indet., Enchodus petrosus, E. ferox, E. cf. gladiolus, E. spp., Alepisauroidei indet.), two plesiosaurs (Polycotylidae indet., Plesiosauria indet.), and one mosasaurid (Tylosaurinae indet.). Based on the faunal assemblage, a Santonian-?early Campanian age is proposed. Lamniform sharks are the best represented group in terms of taxic diversity and relative abundance, probably reflecting the peak in diversity this group experienced following the Cenomanian radiation in the Late Cretaceous. The faunal assemblage of Akkermanovka exhibits significant taxonomic overlaps with assemblages reported from Asia and North America, but not from Southern Hemisphere continents, indicating east-west dispersal of several marine taxa during the Late Cretaceous.

6.
Animals (Basel) ; 14(9)2024 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-38731285

RESUMEN

In the ex situ conservation of chondrichthyan species, successful reproduction in aquaria is essential. However, these species often exhibit reduced reproductive success under human care. A key aspect is that conventional sperm analyses do not provide insights into the functional competence of sperm. However, proteomics analysis enables a better understanding of male physiology, gaining relevance as a powerful tool for discovering protein biomarkers related to fertility. The present work aims to build the first proteome database for shark semen and to investigate the proteomic profiles of seminal plasma and spermatozoa from small-spotted catsharks (Scyliorhinus canicula) related to the underlying adaptations to both natural and aquarium environments, thereby identifying the reproductive impact in aquarium specimens. A total of 305 seminal plasma and 535 spermatozoa proteins were identified. Among these, 89 proteins (29.2% of the seminal plasma set) were common to both spermatozoa and seminal plasma. In the seminal plasma, only adenosylhomocysteinase protein showed differential abundance (DAP) between wild and aquarium animals. With respect to the spermatozoa proteins, a total of 107 DAPs were found between groups. Gene Ontology enrichment analysis highlighted the primary functional roles of these DAPs involved in oxidoreductase activity. Additionally, KEGG analysis indicated that these DAPs were primarily associated with metabolic pathways and carbon metabolism. In conclusion, we have successfully generated an initial proteome database for S. canicula seminal plasma and spermatozoa. Furthermore, we have identified protein variations, predominantly within spermatozoa, between aquarium and wild populations of S. canicula. These findings provide a foundation for future biomarker discovery in shark reproduction studies. However, additional research is required to determine whether these protein variations correlate with reproductive declines in captive sharks.

7.
Ecol Evol ; 14(3): e11163, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38500855

RESUMEN

While sexual size dimorphism (SSD) is abundant in nature, there is huge variation in both the intensity and direction of SSD. SSD results from a combination of sexual selection for large male size, fecundity selection for large female size and ecological selection for either. In most vertebrates, it is variation in the intensity of male-male competition that primarily underlies variation in SSD. In this study, we test four hypotheses regarding the adaptive value of SSD in sharks-considering the potential for each of fecundity, sexual, ecological selection and reproductive mode as the primary driver of variation in SSD between species. We also estimate past macroevolutionary shifts in SSD direction/intensity through shark phylogeny. We were unable to find evidence of significant SSD in early sharks and hypothesise that SSD is a derived state in this clade, that has evolved independently of SSD observed in other vertebrates. Moreover, there is no significant relationship between SSD and fecundity, testes mass or oceanic depth in sharks. However, there is evidence to support previous speculation that reproductive mode is an important determinant of interspecific variation in SSD in sharks. This is significant as in most vertebrates sexual selection is thought to be the primary driver of SSD trends, with evidence for the role of fecundity selection in other clades being inconsistent at best. While the phylogenetic distribution of SSD among sharks is superficially similar to that observed in other vertebrate clades, the relative importance of selective pressures underlying its evolution appears to differ.

8.
J Morphol ; 285(2): e21673, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38361272

RESUMEN

Recent studies have uncovered mosaic patterns of allometric and isometric growth underlying ontogenetic shifts in the body form of elasmobranch species (shark and rays). It is thought that shifts in trophic and spatial ecology through ontogeny drive these morphological changes; however, additional hypotheses relating to developmental constraints have also been posed. The bull shark (Carcharhinus leucas) is a large-bodied coastal shark that exhibits strong ontogenetic shifts in trophic and spatial ecology. In this study, we utilise a large data set covering a large number of morphological structures to reveal ontogenetic shifts in the body form of C. leucas, stratifying analyses by sex and size classes to provide fine-scale, more ecomorphologically relevant results. Our results indicate shifts in functional demands across the body through ontogeny, driven by selective pressures relating to trophic and spatial ecology driving the evolution of allometry. We also find significant differences in scaling trends between life stages, and between the sexes, highlighting the importance of utilising large, diverse datasets that can be stratified in this way to improve our understanding of elasmobranch morphological evolution. Ultimately, we discuss the implications of these results for existing ecomorphological hypotheses regarding the evolution of specific morphological structures, and pose novel hypotheses where relevant.


Asunto(s)
Tiburones , Animales
9.
Mar Pollut Bull ; 201: 116155, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38401387

RESUMEN

Sharks are particularly susceptible to bioaccumulation due to their life history characteristics and trophic position within marine ecosystems. Despite this, studies of bioaccumulation cover only a small proportion of extant species. In this study we report concentrations of trace elements and heavy metals in blood samples of Sphyrna lewini for the first time. We report high concentrations of several trace elements and heavy metals, with concentrations of some elements exceeding the limit determined safe for human consumption. High elemental concentrations may reflect biochemical differences between blood plasma and other tissues; however, they may also be symptomatic of high levels of exposure triggered by anthropogenic activities. We also provide evidence of elemental accumulation through ontogeny, the nature of which differs from that previously reported. Ultimately, this baseline study increases our understanding of interspecific and intraspecific variation in bioaccumulation and ecotoxicology in elasmobranchs which may prove important in ensuring adequate management.


Asunto(s)
Metales Pesados , Tiburones , Oligoelementos , Animales , Bahías , Ecosistema , México
10.
Life (Basel) ; 13(10)2023 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-37895466

RESUMEN

The white shark, Carcharodon carcharias, is the main top predator of the present-day Mediterranean Sea. The deep past of C. carcharias in the Mediterranean is witnessed by a rather conspicuous, mostly Pliocene fossil record. Here, we provide a synthesis of the palaeobiology and palaeoecology of the Mediterranean white sharks. Phenetically modern white shark teeth first appeared around the Miocene-Pliocene transition in the Pacific, and soon after in the Mediterranean. Molecular phylogenetic analyses support an origin of the Mediterranean white shark population from the dispersal of Australian/Pacific palaeopopulations, which may have occurred through the Central American Seaway. Tooth dimensions suggest that the Mediterranean white sharks could have grown up to about 7 m total length during the Pliocene. A richer-than-today marine mammal fauna was likely pivotal in supporting the Mediterranean white sharks through the Pliocene and most of the Quaternary. White sharks have seemingly become more common as other macropredators declined and disappeared, notwithstanding the concurrent demise of many potential prey items in the context of the latest Pliocene and Quaternary climatic and environmental perturbations of the Mediterranean region. The overall generalist trophic habits of C. carcharias were likely crucial for securing ecological success in the highly variable Mediterranean scenario by allowing the transition to a mostly piscivorous diet as the regional marine mammal fauna shrank.

11.
Int. j. morphol ; 41(5): 1304-1309, oct. 2023. ilus
Artículo en Español | LILACS | ID: biblio-1521013

RESUMEN

Los trabajos realizados sobre batoideos han demostrado que existen grandes variaciones en la musculatura de la región cefálica ventral, estos cambios están asociados a los diferentes estilos de vida de los organismos y por tanto, a los mecanismos de alimentación. El objetivo de este trabajo fue llevar a cabo un estudio comparativo de la morfología de la musculatura cefálica dorsal y ventral de dos especies de la familia Narcinidae: Narcine vermiculatus y Diplobatis ommata. Se observó que ambas especies comparten un patrón morfológico común. Los músculos que mostraron mayores variaciones en la región dorsal fueron el depresor rostral, el preorbital lateral y el elevador rostral. La diferencia más importante en esta región, entre ambas especies, fue la ausencia del músculo cucularis en D. ommata. En la región ventral las principales diferencias se observaron en los músculos depresor mandibular, preorbital medial, interbranquial y depresor hiomandibular. Este último músculo está formado por dos paquetes en D. ommata, en tanto que en N. vermiculatus por uno. Se puede concluir que la morfología de la musculatura cefálica es constante; sin embargo, se observan diferencias importantes en el grado de desarrollo de los músculos tanto en la región dorsal como en la ventral.


SUMMARY: Works conducted on batoids have revealed large variations in the musculature of the ventral cephalic region, associated to the different lifestyles of these organisms and, therefore, to their feeding mechanisms. This work aimed to conduct a comparative study of the dorsal and ventral cephalic muscular morphology of two species of the family Narcinidae: Narcine vermiculatus and Diplobatis ommata. It was observed that both species share a common morphological pattern. Muscles with larger variations in the dorsal region were the rostral depressor, the lateral preorbital and the rostral elevator. The most relevant difference in this region between both species was the absence of the cucularis muscle in D. ommata. In the ventral region, the main differences were observed in the mandibular depressor, medial preorbital, interbranchial and hyomandibular depressor muscles. In D. ommata, the latter is formed by two packages, and by one in N. vermiculatus. It can be concluded that the cephalic musculature is constant; however, significant differences are observed in the muscle development degree in both the dorsal and the ventral regions.


Asunto(s)
Animales , Músculo Esquelético/anatomía & histología , Elasmobranquios/anatomía & histología , Cabeza/anatomía & histología , Variación Anatómica
12.
Microorganisms ; 11(8)2023 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-37630528

RESUMEN

The current climate change scenario caused by anthropogenic activities has resulted in novel environmental pressures, increasing the occurrence and severity of fungal infections in the marine environment. Research on fungi in several taxonomic groups is widespread although not the case for elasmobranchs (sharks and rays). In this context, the aim of the present study was to screen the oral fungal microbiota present in artisanally captured Rioraja agassizii, a batoid that, although endangered, is highly fished and consumed worldwide. Oropharyngeal samples were obtained by swabbing and the samples were investigated using morphological and phenotypic methods by streaking on Sabouraud Dextrose Agar (SDA) and subculturing onto CHROMagar Candida (BD Difco) and CHROMagar Candida Plus (CHROMagarTM), as well as molecular techniques by amplification of the ITS1-5.8S-ITS2 ribosomal DNA region and a MALDI-TOF MS assessment. The findings indicated the presence of Candida parapsilosis (seven isolates), Candida duobushaemulonii (one isolate) and Rhodotorula mucilaginosa (three isolates), several of these reported for the first time in Rioraja agassizii. In addition, a 100% agreement between the MALDI-TOF results and partial ITS region sequencing was noted, demonstrating that the MALDI-TOF MS is a rapid and effective alternative for yeast identification in Rioraja agassizii isolates and potentially in other elasmobranch species. These findings highlight the need for further research to determine the potential impact on elasmobranch health, ecology, and commercial fisheries. Furthermore, this research is paramount in a One Health framework and may be employed to predict elasmobranch responses to an evolving ocean, keep healthy populations in check, monitor species, and assess the public health consequences of consuming these species.

13.
J Morphol ; 284(8): e21608, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37458085

RESUMEN

The central tenet of ecomorphology links ecological and morphological variation through the process of selection. Traditionally used to rationalise morphological differences between taxa, an ecomorphological approach is increasingly being utilised to study morphological differences expressed through ontogeny. Elasmobranchii (sharks, rays and skates) is one clade in which such ontogenetic shifts in body form have been reported. Such studies are limited to a relatively small proportion of total elasmobranch ecological and morphological diversity, and questions remain regarding the extent to which ecological selection are driving observed morphometric trends. In this study, we report ontogenetic growth trajectories obtained via traditional linear morphometrics from a large data set of the brown smoothhound shark (Mustelus henlei). We consider various morphological structures including the caudal, dorsal and pectoral fins, as well as several girth measurements. We use an ecomorphological approach to infer the broad ecological characteristics of this population and refine understanding of the selective forces underlying the evolution of specific morphological structures. We suggest that observed scaling trends in M. henlei are inconsistent with migratory behaviour, but do not contradict a putative trophic niche shift. We also highlight the role of predation pressure and sex-based ecological differences in driving observed trends in morphometry, a factor which has previously been neglected when considering the evolution of body form in sharks.


Asunto(s)
Tiburones , Rajidae , Animales , Tiburones/anatomía & histología , Rajidae/anatomía & histología
14.
Biology (Basel) ; 12(7)2023 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-37508405

RESUMEN

Sampling efforts on the Saya de Malha Bank (part of the Mascarene Plateau, western Indian Ocean) unveiled three unusual small juvenile angel shark specimens, that were a much paler color than the only known western Indian Ocean species, Squatina africana Regan, 1908. However, it took many years before further specimens, including adults of both sexes, and tissue samples were collected. The present manuscript contains a redescription of S. africana based on the holotype and additional material, as well as the formal description of the new species of Squatina. All specimens of the new species, hereafter referred to as Squatina leae sp. nov., were collected in the western Indian Ocean off southwestern India and on the Mascarene Plateau at depths of 100-500 m. The new species differs from S. africana in a number of characteristics including its coloration when fresh, smaller size at birth, size at maturity, and adult size, genetic composition, and distribution. Taxonomic characteristics include differences in the morphology of the pectoral skeleton and posterior nasal flap, denticle arrangement and morphology, vertebral counts, trunk width, pectoral-pelvic space, and clasper size. A key to the species of Squatina in the Indian Ocean is provided.

15.
Ecol Evol ; 13(6): e10204, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37332516

RESUMEN

Sharks, rays, and chimaera form the clade Chondrichthyes, an ancient group of morphologically and ecologically diverse vertebrates that has played an important role in our understanding of gnathostome evolution. Increasingly, studies seek to investigate evolutionary processes operating within the chondrichthyan crown group, with the broad aim of understanding the driving forces behind the vast phenotypic diversity observed among its constituent taxa. Genetic, morphological, and behavioral studies have all contributed to our understanding of phenotypic evolution yet are typically considered in isolation in the context of Chondrichthyes. In this viewpoint, I discuss why such isolation is prevalent in the literature, how it constrains our understanding of evolution, and how it might be overcome. I argue that integrating these core fields of organismal biology is vital if we are to understand the evolutionary processes operating in contemporary chondrichthyan taxa and how such processes have contributed to past phenotypic evolution. Despite this, the necessary tools to overcome this major limitation already exist and have been applied to other taxa.

16.
J Morphol ; 284(5): e21585, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-37059594

RESUMEN

Lamniform sharks are one of the more conspicuous groups of elasmobranchs, including several emblematic taxa as the white shark. Although their monophyly is well supported, the interrelationships of taxa within Lamniformes remains controversial because of the conflict among various previous molecular-based and morphology-based phylogenetic hypotheses. In this study, we use 31 characters related to the appendicular skeleton of lamniforms and demonstrate their ability to resolve the systematic interrelationships within this shark order. In particular, the new additional skeletal characters resolve all polytomies that were present in previous morphology-based phylogenetic analyses of lamniforms. Our study demonstrates the strength of incorporating new morphological data for phylogenetic reconstructions.


Asunto(s)
Elasmobranquios , Tiburones , Animales , Filogenia , Tiburones/anatomía & histología , Huesos
17.
Chemosphere ; 324: 138262, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36870615

RESUMEN

This is the first research that extensively compiles all the available scientific literature on the presence of trace metals (TMs), persistent organic pollutants (POPs), and plastic debris in Chondrichthyan species inhabiting South America (including the Atlantic and Pacific Oceans), providing an insight into Chondrichthyans as bioindicators of pollutants as well as the impacts of pollutant exposure on the organisms. Seventy-three studies were published in South America between 1986 and 2022. While 68.5% focused on TMs, 17.8% on POPs, and 9.6% on plastic debris. Brazil and Argentina were at the top in terms of the number of publications; however, there is an absence of information regarding pollutants for Chondrichthyans in Venezuela, Guyana, and French Guiana. Of the 65 Chondrichthyan species reported, 98.5% belong to the Elasmobranch group, and 1.5% from the Holocephalans. Most studies focused on Chondrichthyans of economic importance, and the most analyzed organs were the muscle and liver. There is a lack of studies on Chondrichthyan species with low economic value and critical conservation status. Due to their ecological relevance, distribution, accessibility, high trophic position, capacity to accumulate high levels of pollutants, and the number of studies published, Prionace glauca and Mustelus schmitii seem to be adequate to serve as bioindicators. For TMs, POPs, and plastic debris there is a lack of studies focusing on the pollutant levels as well as their effect on Chondrichthyans. Future research reporting TMs, POPs, and plastic debris occurrences in Chondrichthyan species are required in order to increase the scarce databases about pollutants in this group, with a clear need for further research on the responses of chondrichthyans to pollutants, as well as making inferences about the potential risks to the ecosystems and human health.


Asunto(s)
Contaminantes Químicos del Agua , Contaminantes del Agua , Humanos , Biomarcadores Ambientales , Ecosistema , Contaminantes Químicos del Agua/análisis , Plásticos , Brasil , Monitoreo del Ambiente
18.
PeerJ ; 10: e14190, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36285333

RESUMEN

The Niubu fossil locality in Chiayi County, southern Taiwan is best known for its rich early Pleistocene marine fossils that provide insights into the poorly understood past diversity in the area. The elasmobranch teeth at this locality have been collected for decades by the locals, but have not been formally described and have received little attention. Here, we describe three museum collections of elasmobranch teeth (n = 697) from the Liuchungchi Formation (1.90-1.35 Ma) sampled at the Niubu locality, with an aim of constructing a more comprehensive view of the past fish fauna in the subtropical West Pacific. The assemblage is composed of 20 taxa belonging to nine families and is dominated by Carcharhinus and Carcharodon. The occurrence of †Hemipristis serra is of particular importance because it is the first Pleistocene record in the area. We highlight high numbers of large Carcharodon carcharias teeth in our sample correlating to body lengths exceeding 4 m, along with the diverse fossil elasmobranchs, suggesting that a once rich and thriving marine ecosystem in an inshore to offshore shallow-water environment during the early Pleistocene in Taiwan.


Asunto(s)
Ecosistema , Tiburones , Animales , Taiwán , Fósiles , Peces
19.
Naturwissenschaften ; 109(4): 39, 2022 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-35913537

RESUMEN

Records of chondrichthyan egg capsule morphotypes from the paralic deposits of the Belgian Coal Measures Group (Pennsylvanian; Bashkirian-Moscovian; Namurian B-Westphalian B according to the traditional subdivision) are presented and discussed. These include several species of the hybodontiform type Palaeoxyris as well as the putative holocephalian types Vetacapsula and Crookallia. Furthermore, the type specimens of Scapellites cottoni and S. minor, two additional putative and enigmatic egg capsules from the same lithostratigraphic unit, are figured and discussed. Altogether, a highly diverse egg capsule assemblage documented from the Belgian deposits implies the presence of at least eleven different Carboniferous chondrichthyan species using the ancient aquatic environments for spawning and as nurseries. The absence of the xenacanthiform morphotype Fayolia, known from surrounding coeval Coal Measures areas of northern France, the Netherlands, and Germany, is conspicuous. This lack may be a result of collecting bias and does not reflect a real pattern.


Asunto(s)
Carbón Mineral , Bélgica , Francia , Alemania
20.
Mar Environ Res ; 179: 105692, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35785679

RESUMEN

Offshore oil and gas platforms have the potential to provide complex refugia for fish and benthic colonisers. We compare two methods of biodiversity assessment for fish and elasmobranchs at seven decommissioned oil and gas platforms as well as five sediment sites, located 5 km from platforms, in the Gulf of Thailand. Using surveys from stereo-video ROV transects, and data from Environmental DNA (eDNA) water-column samples, we detected fish and elasmobranch taxa from 39 families and 66 genera across both platform and sediment sites with eDNA, compared with 18 families and 29 genera by stereo-ROV with platforms yielding significantly greater species richness. This study demonstrates that the combination of stereo-video ROV and eDNA provide effective, non-extractive and complementary methods to enhance data capture. This approach sets new benchmarks for evaluating fish assemblages surrounding platforms and will enhance measurements of biota to inform decisions on the fate of oil/gas infrastructure.


Asunto(s)
Biodiversidad , Peces , Animales , Código de Barras del ADN Taxonómico , Monitoreo del Ambiente/métodos
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