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    NIA Best Student Paper and Ichthyology I

    2021-07-22   10:45 - 12:15

    Moderator: Mark Sabaj Perez

    1.  10:45  VIRTUAL    River Capture Isolated Multiple Low-diversity, Early-branching Clades of Sternopygid Electric Fishes on the Guiana Shield (NIA Student Paper Competition). Kevin T. Torgersen*, University of Louisiana at Lafayette; James S. Albert, University of Louisiana at Lafayette

    Patterns of biogeography and phylogeny can illuminate the processes of evolutionary diversification in the formation of species-rich Amazonian aquatic ecosystems. Prominent patterns like the core-periphery pattern of inverse species richness and percent endemism are predicted by the river capture hypothesis, which posits larger and more frequent river capture events in the Amazon-Orinoco lowlands (c. 250 m). River capture is predicted to increase geographic isolation and connections among taxa in portions of adjacent river networks, leading to greater species richness and lower percent endemism. Further, modelling studies predict river capture to generate low-diversity, early-branching (LDEB) clades at the geographic periphery. Here we evaluate patterns of species richness and endemism in two clades of sternopygid electric fishes from the Guiana Shield and adjacent areas of the Amazonian lowlands: the Sternopygus astrabes group (Sternopyginae) and Japigny(Eigenmanninae). We find these clades: 1, are represented by multiple putative species-level taxa, most being currently undescribed; 2, share an otherwise unique pigment pattern of alternating broad vertical dark and light bars, perhaps indicting either convergent evolution and/or horizontal gene transfer (i.e. hybridization) in sympatry, and 3, represent LDEB members of Sternopyginae and Eigenmanninae, respectively, which elevate the phylogenetic diversity of these subfamily-level taxa at the continental periphery. These results are consistent with the expectations of river capture in upland and lowland settings, and for Paleogene origins of the LDEBSternopygus astrabes group and Japignyin the Guiana Shield.

    2.  11:00  IN-PERSON    Reproductive Behavior of Gomphosus varius (Labridae) in Relation to Current Patterns at a Spawning Aggregation Site: Implications for Larval Dispersal (NIA Student Paper Competition). Ka'ohinani Kawahigashi*, University of Guam

    A spawning aggregation is an effective and common reproductive strategy among reef fish species, in which conspecific fish congregate for the sole purpose of mating. The bird wrasse, Gomphosus varius, is a tropical reef fish that forms residential spawning aggregations at specific sites daily if local population densities are relatively high. In this study, I use G. varius as a model species for analyzing some of the ecological characteristics of reef fish spawning aggregations. Finger Reef, Apra Harbor, Guam Is a multi-species spawning aggregation site for several wrasse species, including G. varius. This speciesutilizes a lek-like mating system while aggregating and a haremic mating system when not. The objectives of this study are to (1) understand the social and territorial dynamics of this wrasse's lek-like mating system, (2) determine the optimal oceanographic and environmental conditions at a given site that promote spawning at this aggregation site, and (3) determine the dispersal patterns of pelagic G. varius eggs from this site. Since October 2018, field observations were conducted at Finger Reef to determine if G. varius spawning patterns correlate with tidal, current, lunar and seasonality patterns, mating territory defense, territory location within the aggregation site, and social interactions. Observations of mating territory defense, courtship and spawning success provide insight towards understanding the structure and function of this spawning aggregation. Additionally, ongoing drifter release experiments will determine if pelagic eggs are largely retained or dispersed from the site during peak spawning times.

    3.  11:15  IN-PERSON    Mating Success of the Six-Bar Wrasse (Thalassoma hardwicke, Labridae) Utilizing Two Mating Strategies. Kelsie Ebeling-Whited*, University of Guam

    Spawning aggregations are a critical aspect of population resilience and fisheries sustainability for many fish species. Many species of wrasse and parrotfish (Labridae) will spawn within an aggregation, but the dynamics of these aggregations vary. This study used a combination of methods to investigate the spawning behavior of Thalassoma hardwicke in a daily resident spawning aggregation at Finger Reef, Apra Harbor, Guam. Within the aggregation, terminal phase (TP) males pair spawn with initial phase (IP) females while (IP) males and females spawn in groups. Group spawning was the more successful spawning strategy within this aggregation. The abundance of T. hardwicke did not affect spawning success or spawning strategy. Spawning success and strategy were not influenced by seasons or tides, and lunar phase did not affect spawning success. Pair spawns, however, occurred more often during the full moon, and group spawns occurred more often during the new moon. Egg predator abundance at Finger Reef did not affect spawning success or influence spawning method. Egg predation was higher in group spawns compared to pair spawns. Finally, some correlation was found between egg predator abundance and egg predation, however, egg predator abundance was not a good predictor of egg predation. These observations increased our knowledge of labrid spawning behavior and will provide a model study to evaluate spawning behavior at other spawning aggregation sites.

    4.  11:30  IN-PERSON    Developmental Ontogeny of Giant Sea Bass, Stereolepis gigas. Emily Ladin*, Cal State University Northridge; Larry Allen, Cal State University Northridge; Michael Franklin, Cal State University Northridge

    Giant Sea Bass, Stereolepis gigas, is listed as critically endangered by the IUCN, and is the largest bony fish off the coast of Southern California. After fertilization, Giant Sea Bass larvae develop in the plankton and eventually settle to a sandy bottom habitat, but little is known about their early life history stages or what mechanisms drive this transition. This study aims to examine, in detail, the first critical stages of this species including the egg, yolk sac, pre-flexion, flexion, post-flexion, and the transformation stages. Laboratory reared specimens were culled throughout development and preserved, the fixed larvae then had their cartilage stained with alcian blue. Following the staining of cartilage, bone was stained using alizarin red. Osteological development will now be analyzed amongst the different sized larvae. Knowledge of these developmental stages will give us a better understanding of what is driving Giant Sea Bass larval recruitment, thus allowing better protection of nursery areas and rational fisheries management.

    5.  11:45  IN-PERSON    Length–Weight relationship of Comelón Megaleporinus muyscorum in the San Jorge River System, Colombia. Javier A. Pájaro-Ledesma, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Isamar Herrera-Higgins, 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; Jesús Vargas-González, 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; Glenys Tordecilla-Petro*, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba

    The length–weight relationship (LWR)of Comelón Megaleporinus muyscorum collected in the San Jorge River System, Colombia, was estimated.The LWR andcondition factor wereestimated with the equation TW = a TLb andK=TW/TLb, respectively.The size ranged between18.0-43.0cm TL, the total weight between62.0-735.0grams,and the mean length in the catch estimated was 29.7 cm TL. LWRestimatedwasTW =0.014 (± 0.09) TL2.87 (± 0.06),r =0.98, n =404,with better condition factor in March,and no statistically significant differences were observed; while the growth coefficient was negative allometric, with statistically significant differences in this case. The information evaluated suggests that Megaleporinus muyscorum is a medium-sized fish,with betterwelfare statein rising waters,negative allometric growth and low correlation between the condition factor and the hydrological cycle of the San Jorge River.

    6.  12:00  IN-PERSON    Spatial and Diel Variation of Fish Sounds on Temperate Artificial Reefs in the Northern Gulf of Mexico. Kelly Boyle*, University of New Orleans; Crystal L. Hightower, University of South Alabama and Dauphin Island Sea Lab; T. Reid Nelson, University of California - Santa Cruz & NOAA Fisheries; Sean Powers, University of South Alabama and Dauphin Island Sea Lab

    Many teleost fishes produce sounds during social and reproductive behavior. Yet, the contribution of fish sounds to spatial, diel, and seasonal variation to the soundscape is lacking for many habitats. In this study, we examined variation in the composition and occurrence of fish sounds around 18 artificial reefs in the Reef Permit zone off the coast of Alabama from recordings made using passive acoustic monitoring (PAM) devices. In 2017 (late spring – summer) and 2018 (summer), we recorded 2,300+ hours from multiple reef types (9 pyramids, 4 tanks, 2 bridge rubble reefs, 3 chicken coops) over 40 days in both years. Video from recorder deployment dives was used to identify > 30 fish species among reefs. We observed several distinctive fish sound types on recordings. We detected sounds from several known sound producing taxa (e.g., leopard toadfish Opsanus pardus, damselfish Stegastesspp., and cusk-eels Ophidiidae). We quantified relative frequency of occurrence of sounds over time and among reefs using semi-automated screening methods. Some sounds were more frequent at night (e.g. leopard toadfish calls, unknown pop sounds, and pulse train sounds), while other sounds occurrences were mainly diurnal. An analysis currently in progress is assessing the co-variation of fish sound patterns with relative abundance of observed fish species. Results thus far indicate a high degree of variation of fish sound types on different reefs and among reef types. The diverse sound repertoires of temperate reef fishes in the Gulf of Mexico may provide potential for monitoring presence, absence, and relative abundance with PAM.

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