V: Ichthyology VII2021-07-26 10:45 - 12:00 |
| Moderator: Hannah Owens |
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2. 10:45 VIRTUAL Evolution of The Symbiosis Between Fishes And Gelatinous Invertebrates: a Case Study on The Stromateiformes (Teleostei, Percomorphacea). Murilo Pastana*, Smithsonian Institution; G. David Johnson, Smithsonian Institution; Alessio Datovo, Museu de Zoologia - USP murilo_pastana@hotmail.com
The association of fishes with floating objects in open waters is quite common and possibly a primitive behavior of these animals. Swimming around drifting objects enhances visibility and spatial orientation and helps the fish to quickly detect prey and/or the approach of possible predators. Drifting algae, seaweed or logs are among the objects most commonly followed by fishes, but records of these animals using debris, boats, and even garbage are also available. Most fishes avoid close proximity to pelagic cnidarians since these animals represent one of their natural predators. However, some marine fishes intentionally associate with jellyfish and other gelatinous invertebrates. Among those fishes, Stromateiformes are often recorded swimming around pelagic cnidarians and tunicates. All 16 stromateiform genera develop some sort of association with cnidarians at some phase of their lives. When mapped on our recent phenotypic phylogeny of stromateiforms, the fish-gelata symbiosis is optimized as primitive for the order. Among the symbionts used by Stromateiformes, jellyfishes are the most common host and used by four of the six stromateiform families, whereas two other families independently changed hosts to salps and pyrosomes. In the molecular-based phylogenies, however, the stromateiform symbiosis with gelatinous invertebrates would have evolved independently at least three times. Studying the fish-cnidarian association in a cladistic framework allows us to elucidate the evolutionary history of the complex association of Stromateiformes with pelagic cnidarians. |
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3. 11:00 VIRTUAL Reproductive biology of Comelón Megaleporinus muyscorum in the San Jorge River System, Colombia. Elkin D. Calderín-González, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Karolay Arrieta-Ramírez, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Angel L. Martínez-González, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Glenys Tordecilla-Petro, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Charles W. Olaya-Nieto, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Fredys F. Segura-Guevara*, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba ffsegura@correo.unicordoba.edu.co
To study the reproductive biology of Comelón Megaleporinus muyscorum in the San Jorge River System, Colombia, 404 individualswith totallength (TL) ranged betweenentre 18.0-43.0cm and total weight (TW) ranged betweeny 62.0-735.0grams were collected. The gonads were placed in Gilson solution, the Vazzoler scale was applicated and sex ratio, maturity index, spawning season, length at first maturity, ovocites’s diameter and fecundity were estimated. It was found 273 females, 128 males and 3 undifferentiated individuals, with mean catch length of 29.7 cm TL, with sexual dimorphism to size, length at first maturity was 29.7 cm TL for both sexes, the oocytes´s diameter measured 950 ?m and average fecundity was 60359 oocytes. The results obtained suggest that Comelon is a fish with synchronous oocyte development in two groups, an annual spawning with a reproductive period that extends from February to November influenced by the water level of the San Jorge River, medium-sized oocytes and high fecundity associated with the ovaries´weight. |
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4. 11:15 VIRTUAL Feeding ecology of Comelón Megaleporinus muyscorum in the San Jorge River System, Colombia. José S. Pérez-Orozco, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Kely J. Monterrosa-Jaraba, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Fredys, F. Segura-Guevara, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Glenys Tordecilla-Petro, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Charles W. Olaya-Nieto, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Ángel L. Martínez-González*, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba angelmartinezg@correo.unicordoba.edu.co
To evaluate the feeding ecology of Comelón Megaleporinus muyscorumin the San Jorge River System, Colombia,we analyzed 394 stomachs of individuals collected between January and December 2013, withtotallength (TL) and total weight (TW) ranged between18.0-43.0 cm and 62.0-735.0 grams.The stomach content was evaluate using the proportion of empty stomachs, grade of digestion, frequency of occurrence, numerical frequency, gravimetry and relative importance index. The proportion of empty stomachs was low and most of the foods were half digested and five food groups were identified: vegetable remains, fishes, debris, insects and others. Vegetable remains was the most common group (91.1%), the most abundant group (59.8%), the greatest group composition in weight (71.1%) and themain food in theComelón´s diet. The results suggestthat M. muyscorumis a omnivorous fish with a herbivorous trend, which keeps your food preferences as it grows throughout the year and the hydrological cycle of theSan Jorge River System. |
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5. 11:30 VIRTUAL Trophic ecology of Nicuro Pimelodus yuma in the San Jorge River Basin, Colombia. María P. Gómez-Rodríguez, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Rosalba Lambertinez-Sibaja, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Ángel L. Martínez-González, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Fredys, F. Segura-Guevara, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Glenys Tordecilla-Petro, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Charles W. Olaya-Nieto*, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba colaya@correo.unicordoba.edu.co
Trophic ecology of Nicuro Pimelodus yuma in the San Jorge River Basin, Colombia, was evaluated. We analyzed 402 stomachs of individuals collected between January and December 2013, withtotallength (TL) and total weight (TW) ranged between14.9-30.6 cm and 33.0-243.0 grams.The stomach contents wereanalyzed using the Proportion of empty stomachs, Grade of digestion, Frequency of occurrence, numerical Frequency, Gravimetry and relative importance Index.A third of the stomachs were found empty, 40.9% of the prey were fresh and five food groups were identified:vegetable remains, fishes, insects, debris and others.Vegetable remains was the most frequent food group(73.8%),the most abundant group (50.4%), the greatest group composition in weight (57.3%) and themain food in the Nicuro´s diet(IIR =42.3%),while other food groups are classified as occasional food groups with low relative importance. The results suggestthat Pimelodus yumais a omnivorous fish with a herbivorous trend, which keeps your food preferences as it grows throughout the year and the hydrological cycle of theSan Jorge River. |
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6. 11:45 VIRTUAL Trophic ecology of co–occurring fishes in the Sundays River valley ponds, assessed using stable isotope and gut content analyses. Lubabalo Mofu*, DSI/NRF Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity (SAIAB); Tatenda Dalu, Department of Biology and Environmental Sciences, University of Mpumalanga; Ryan Wasserman, Rhodes University; Darragh Woodford, Centre for Invasion Biology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand; Olaf Weyl, DSI/NRF Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity (SAIAB) l.mofu@saiab.ac.za
The analysis of food web structures has increased our understanding of the dynamics of organisms belonging to different trophic levels. Here, the diet of two native species, Glossogobius callidus and Gilchristella aestuaria were assessed in the presence of two alien species, Oreochromis mossambicus and Gambusia affinisin irrigation ponds, Eastern Cape, South Africa. Carbon and nitrogen stable isotope and gut content analyses were used to estimate the proportion of diet assimilation among the four fish species. Stable isotope analysis revealed thatboth G. affinis and O. mossambicus had a larger isotopic niche width than G. callidus and G. aestuaria. While, G. callidus fed on benthic resources and G. aestuaria fed on phytoplankton. However, gut content analysis showed that G. callidus, O. mossambicus and G. affinis fed predominantly on benthic resources, while G. aestuaria fed mainly on plankton resources. The isotopic niche of the small size–class of these species showed a variable niche overlap between species.However, despite the overall high degree of overlap observed from the SIBER results, subtle differences were observed for large size–classes.This study contributes valuable information in understanding trophic relationships that can develop from introduction of alien species into new environments. Keywords:Food web; trophic position; stable isotope; gut content; niche, ontogeny |