Latest Articles from Zoologia Latest 5 Articles from Zoologia https://zoologia.pensoft.net/ Thu, 28 Mar 2024 13:45:45 +0200 Pensoft FeedCreator https://zoologia.pensoft.net/i/logo.jpg Latest Articles from Zoologia https://zoologia.pensoft.net/ DNA barcoding of a tropical anguillid eel, Anguilla bicolor (Actinopterygii: Anguilliformes), in Indo-Pacific region and notes on its population structure https://zoologia.pensoft.net/article/59332/ Zoologia 38: 1-7

DOI: 10.3897/zoologia.38.e59332

Authors: Ahmad Fathi Norarfan, Siti Shazwani Azreena Mokti, Hussein Taha, Muhamad Amin, Muhamad Ali, Takaomi Arai

Abstract: The tropical anguillid eel, Anguilla bicolor McCelland, 1844, includes two subspecies, Anguilla bicolor bicolor McCelland, 1844 and Anguilla bicolor pacifica Schmidt, 1928, and is distributed across the Indo-Pacific region. Although A. bicolor is widely distributed and recognized as an important fish resource in the Indo-Pacific region, few studies have been conducted on its genetic variation and population structure. DNA barcoding of A. bicolor specimens collected in the Indo-Pacific region was carried out in this study using mitochondrial cytochrome c oxidase subunit I. Anguilla bicolor was found to diverge genetically, which supported its classification into two different subspecies. In addition, our study showed that A. bicolor bicolor had two genetically distinct populations/groups, and these different populations co-occur geographically in Indonesia and Malaysia in the eastern Indian Ocean. Our findings suggest that the eel larvae might be transported from at least two geographically different spawning grounds in the Indian Ocean, and then recruited to and settled in the same habitats in Indonesian and Malaysian waters. The molecular evidence calls for further research on the life history, stock assessment and protection of the populations of A. bicolor bicolor in Indonesia and Malaysia.

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Short Communication Wed, 24 Mar 2021 22:19:54 +0200
Ecological separation by ecomorphology and swimming performance between two congeneric fish species https://zoologia.pensoft.net/article/47223/ Zoologia 37: 1-8

DOI: 10.3897/zoologia.37.e47223

Authors: Rafael C. R. Souza, Paulo S. Pompeu

Abstract: The high diversity of freshwater fish species reflects a great morphological plasticity. Understanding the relationship between swimming capacity, morphology and habitat use may be important to predict the chances of finding a species at an anthropized environment. The swimming capacity and morphological aspects of two sympatric species of Characidium, and for which spatial segregation in different hydraulic habitats is known, were compared in this study. Twenty-one individuals of Characidium fasciatum Reinhardt, 1867 and 23 individuals of Characidium cf. zebra Eigenmann, 1909 were captured and used for the evaluation of the swimming capacity and ecomorphological attributes. The swimming capacity of each species was obtained by measuring critical and relative velocities. A total of 12 ecomorphological attributes correlated with habitat use and swimming characteristics were also compared. The Mann-Whitney mean test showed that the swimming capacity of C. fasciatum was greater than that of C. cf. zebra, and the standard length of the individuals explained 12.42% of the variation in their capacity to withstand water flow. Both species were morphologically distinct in the relative length of the caudal peduncle, ventral flattening index and the relative area of the pectoral fin. The relative area of the pectoral fin alone accounted for 16.71% of the differences in the ability to resist the water flow and which were not explained by body length. Our results showed that two species differed in the ecomorphological space and in their swimming capacity, supporting the hypothesis that the greater the hydrodynamism, the better a fish is able to withstand the water flow, and that this capacity is correlated with the morphological characteristics linked to the swimming activity of the fish.

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Research Article Thu, 3 Dec 2020 20:53:02 +0200
Occurrence and ecological implication of a tropical anguillid eel, Anguilla marmorata, in Brunei Darussalam, Borneo Island https://zoologia.pensoft.net/article/39468/ Zoologia 37: 1-7

DOI: 10.3897/zoologia.37.e39468

Authors: Nur Dhabita Zan, Ain Sarbini, Hussein Taha, Iy Vonne Tan, Azie Azri, Rafhiah Kahar, Faizah Metali, Norhayati Ahmad, Takaomi Arai

Abstract: Tropical anguillid eels account for two-thirds of the 19 species in Anguilla Schrank, 1798. However, information on the species diversity, geographical distribution, and life histories of the tropical eels is very limited. Recent studies suggested that morphological species identification of the tropical anguillid eels should be validated by molecular analysis for accurate identification. After surveying for three years, two anguillid eels were found in Brunei Darussalam, Borneo Island. They were firstly identified as Anguilla marmorata Quoy & Gaimard, 1824 using morphological analysis and further gene analysis of cytochrome c oxidase subunit I (COI) confirmed the species identification. This study is the first comprehensive description of A. marmorata in Brunei Darussalam, Borneo Island. Furthermore, it is also the first study to validate two anguillid eels collected from the tropical Bonin Islands of Japan as A. marmorata by means of morphological and COI analyses. The molecular phylogenetic tree and haplotype network analyses suggest that A. marmorata found in Brunei Darussalam would belong to the North Pacific population of the westernmost distribution.

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Short Communication Wed, 3 Jun 2020 12:00:02 +0300
Changes in trophic characteristics of two fish species of Astyanax (Teleostei: Characidae) in response to aquatic pollution https://zoologia.pensoft.net/article/30445/ Zoologia 36: 1-12

DOI: 10.3897/zoologia.36.e30445

Authors: Mirella B. Alonso, Débora R. de Carvalho, Carlos B. M. Alves, Marcelo Z. Moreira, Paulo S. Pompeu

Abstract: The trophic plasticity of most fish species of Astyanax Baird & Girard, 1854 in response to environmental changes and resource availability is high. This work evaluates the differences in the trophic characteristics of two congeneric species, Astyanax taeniatus (Jenyns, 1842) and Astyanax lacustris (Lütken, 1875), in Rio das Velhas Basin, which is highly impacted by the discharge of sewage from the Metropolitan Region of Belo Horizonte (MRBH). Eight sites were sampled and grouped into three regions: upper course (two sites upstream of the MRBH); middle course (three sites located in the middle portion of the Rio das Velhas, region with greater influence of the MRBH), and lower course (three sites downstream of the MRBH). Samples of fish and food resources were collected from all sites to obtain the isotopic composition of nitrogen (δ15N) and carbon (δ13C), and the stomach contents of the two species was analized. The most common items in the stomach of A. lacustris and A. taeniatus, respectively, were from plants and insects, followed by algae/periphyton (especially at the low course of Rio das Velhas). In contrast, stable isotope analyses indicated that algae (in polluted sites) and periphyton (in least-disturbed sites) were best assimilated both species. Both analyses indicated that the trophic niches of the two species overlap more in more polluted sites relative to less polluted sites. Astyanax taeniatus and A. lacustris only presented different isotopic composition of carbon and nitrogen in the upper course of the Rio das Velhas, probably in response to the greater diversity of food items consumed by each species. In the other regions, the species presented similar isotopic signatures, with δ15N and δ13C notably enriched in the most polluted regions (middle and low course). Our results suggest that pollution acts by increasing trophic niche overlap of these species, altering the type of resources most assimilated, and promoting a greater enrichment of δ15N in fish and resources.

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Research Article Fri, 5 Jul 2019 16:00:01 +0300
What are the main local drivers determining richness and fishery yields in tropical coastal fish assemblages? https://zoologia.pensoft.net/article/12898/ Zoologia 35: 1-12

DOI: 10.3897/zoologia.35.e12898

Authors: Cynthia Diniz Souza, Vandick S. Batista, Nidia Noemi Fabré

Abstract: Seasonal ecological effects caused by temperature and photoperiod are typically considered minimal in the tropics. Nevertheless, annual climate cycles may still influence the distribution and abundance of tropical species. Here, we investigate whether seasonal patterns of precipitation and wind speed influence the structure of coastal fish assemblages and fishing yields in northeast Brazil. Research trips were conducted during the rainy and dry seasons using commercial boats and gear to sample the fish community. Diversity was analyzed using abundance Whittaker curves, diversity profiles and the Shannon index. Principal Component Analysis (PCA) was used to analyze associations between the abundance of species and various environmental variables related to seasonality. A total of 2,373 fish were collected, representing 73 species from 34 families – 20 of which were classified as both frequent and abundant. Species richness was greater and more equitable during the rainy season than the dry season – driven by changes in the precipitation rather than to wind speed. Species diversity profiles were slightly greater during the rainy season than the dry season, but this difference was not statistically significant. Using PCA was identified three groups of species: the first associated with wind speed, the second with precipitation, and the third with a wide range of sampling environments. This latter group was the largest and most ecologically heterogeneous. We conclude that tropical coastal fish assemblages are largely influenced by local variables, and seasonally mediated by annual changes related to precipitation intensity and wind speed, which in turn influences fishery yields.

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Research Article Fri, 9 Mar 2018 22:26:20 +0200