V: Ichthyology IX2021-07-27 08:00 - 09:30 |
| Moderator: Katriina Ilves |
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1. 08:00 VIRTUAL New sturgeons from the Late Cretaceous of North America, with notes on the Cretaceous record of the family Acipenseridae. Eric Hilton*, Virginia Institute of Marine Science, William & Mary; Lance Grande, Field Museum ehilton@vims.edu
The modern freshwater fish fauna of North America has been intensively studied, although its early evolution is still poorly understood. In particular, the Cretaceous was a time of great evolutionary transformation for the freshwater fish fauna of North America, although the fossil record of this fauna during that time period is extremely poor, with virtually all remains from this time being fragmentary and isolated bones, limiting their phylogenetic and taxonomic information. In this study, the skeletons of newly discovered whole-body fossils of freshwater fishes from the Late Cretaceous Hell Creek Formation were examined. Among these specimens are the remains of two distinct undescribed species of sturgeons (Acipenseridae) preserved in a loosely consolidated matrix. One taxon is represented by a partially preserved skull, and can be diagnosed by a relatively elongate preorbital region (i.e., snout). The second species is represented by two body fossils (including the head and relatively complete postcranial remains) and a third specimen of an intact, three-dimensionally preserved skull and pectoral girdle. This taxon can be diagnosed based on features of the opercular elements. Most sturgeons from the Cretaceous are known by undiagnosable fragmentary remains (i.e., scutes and pectoral-fin spines) or poorly preserved remains (e.g., Protoscaphirhynchus), with Priscosturion and the recently described Anchiacipenser (both monotypic) being rare exceptions. Therefore, these fossils give a rare glimpse into the evolution of Acipenseridae at a critical time in their phylogenetic history, and suggest significant morphological and taxonomic diversity within sturgeons early in their evolution. |
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2. 08:15 VIRTUAL CANCELLED - Neogene megariver captures and the Great Amazonian Biotic Interchange. James Albert*, University of Louisiana at Lafayette jsalbe@gmail.com
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3. 08:30 VIRTUAL Biodiversity of Fishes in the Deep Gulf of Mexico and southeastern US: Continued Insights from Mitochondrial Barcoding and Voucher Specimens. Katriina L. Ilves*, Canadian Museum of Nature; Adela Y. Roa-Varon, Smithsonian Institution, National Museum of Natural History; Dominique Cheb Terrab, Pace University; Michelle Gangone, Pace University; Michael DeGidio, Pace University; Winter Lesnick, Pace University; Steve W. Ross, University of North Carolina at Wilmington; Andrea M. Quattrini, Smithsonian Institution, National Museum of Natural History kilves@nature.ca
The ichthyofauna of deep-sea regions is yet to be fully characterized, with many species still undescribed and cryptic diversity remaining to be uncovered. Here we present the results of a mitochondrial COI barcoding analysis of 245 samples of deep-sea fishes collected at depths ranging from 300 – 1,630 m using trawls, traps, benthic skimmer, and a Johnson-Sea-Link submersible at coral mounds and other hardground habitats in the Gulf of Mexico and western Atlantic Ocean off the southeastern United States. These samples represent 57 putative species, including those only identified to “sp.”, from 27 families, based on preliminary morphological identification. Samples from 32 of these 57 putative species require further examination for reasons such as a genetic match to one (or more) different species in GenBank and/or BOLD, or no close match to any other species. Among these samples is at least one confirmed new species of conger eel (formal description in progress) and potentially several additional new species that require further genetic and morphological examination. In addition, this work contributes first genetic records for four species and at least one genus and highlights the taxonomic uncertainties, and in many cases unreliabilities, in publicly accessible genetic databases and emphasizes the need for additional verification via voucher specimens. This collaborative project further demonstrates the utility of mitochondrial barcoding as a first-pass method to uncover biodiversity for additional study. |
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4. 08:45 VIRTUAL Oceanic Fishes of the Gulf of Mexico and the Deepwater Horizon Disaster: A Decadal Synthesis of Research. Tracey Sutton*, Nova Southeastern University; Kevin Boswell, Florida International University; April Cook, Nova Southeastern University; Maëlle Cornic, Texas A&M Galveston; Rosanna Milligan, Nova Southeastern University; Jon Moore, Florida Atlantic University; Steven Murawski, University of South Florida; Nina Pruzinsky, Nova Southeastern University; Jay Rooker, Texas A&M Galveston; David Wells, Texas A&M Galveston tracey.t.sutton@gmail.com
The open ocean (water column seaward of the 200-m isobath) in the Gulf of Mexico (Gulf hereafter) is the largest ecosystem component, occupying over 97% of its volume. Many assumed that this size would impart resilience to the Deepwater Horizon oil spill disaster (DWH), an assumption that factored into mitigation decisions such as the large-scale injection of subsurface dispersants at great depth. After a decade of research, spearheaded by the $500 million investment of the Gulf of Mexico Research Initiative, we have learned a great deal about the open-ocean Gulf and the impacts of DWH, though much remains unknown. Here we synthesize what we have learned about the oceanic fishes of the Gulf relative to DWH, including the epi-, meso-, and bathypelagic domains. We examine the spectrum of impacts across a wide range of fishes, from larval tunas and billfishes to meso- and bathypelagic predators. In some cases, particularly in lower trophic levels, there were no apparent long-term impacts. In other cases, particularly the meso- and bathypelagic fishes, the impacts were catastrophic and remain so as of this writing. We will discuss attributes of vulnerability and resilience that likely contributed to the observed patterns, and highlight existing data gaps that require sustained observation to assess the full, long-term measure of DWH as well as the potential impacts of future deep-water oil spills. |
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5. 09:00 VIRTUAL The Evolution of Diadromy Drives Elevated Rates of Trait Evolution and Convergence on Multiple Adaptive Peaks. Lindsey DeHaan*, Department of Biological Sciences, Western Michigan University; Michael Burns, Cornell Lab of Ornithology, Cornell University Museum of Vertebrates; Joshua Egan, Department of Biological Sciences, Western Michigan University; Devin Bloom, Department of Biological Sciences, Western Michigan University linzdehaan@gmail.com
Life history strategies can have a profound influence on the dynamics of phenotypic evolution. Diadromy is an extreme type of migration that requires individuals to move tens to thousands of kilometers between marine and freshwater habitats for feeding and reproduction. The high energetic demands of diadromy in fishes are predicted to select for ecomorphological traits that maximize swimming and locomotor efficiency. Indeed, intraspecific studies have shown remarkable divergent selection among diadromous and non-diadromous populations in locomotor and foraging traits, which suggest that diadromous lineages may converge on one or few adaptive peaks at a macroevolutionary scale. We tested for differences in rates and patterns of phenotypic evolution among diadromous and non-diadromous lineages in Clupeiformes, a clade that has evolved diadromy more than 10 times. Our results show that diadromous lineages have significantly faster rates of trait evolution than non-diadromous lineages. We provide evidence that traits associated with locomotion are under strong selection and may have converged on three adaptive peaks in diadromous lineages. We propose that the multiple adaptive peaks are not a direct response to the evolution of diadromy, but instead tied to specific parameters such as migration distance and swimming performance. |
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6. 09:15 VIRTUAL Macroecology in Depth: Estimating Marine Fish Biodiversity in Three Dimensions. Hannah Owens*, University of Copenhagen hannah.owens@gmail.com
Recent estimates of broad-scale marine fish diversity have generally only considered species distributions in two-dimensional space and do not account for depth distribution, which may lead to mis-estimation of species distributions and subsequent diversity estimates, especially among pelagic and benthic species. This aspect of marine distribution modeling has, in general, been largely neglected due to a lack of widely accepted methodological pipelines for three-dimensional distribution inference. Here, I present a possible way forward: generating species distribution models based on environmental data extracted at the depths where individuals were observed. I tested this method on marine Atlantic representatives of three orders of fishes: Gadiformes, Scombriformes, and Beloniformes. My results show biodiversity estimates based on two-dimensional models are likely underestimating the latitudinal breadth of deep-sea fish distributions, an error compounded when maps of these distributions are stacked to estimate biodiversity. Three-dimensional models not only provide not only a likely more accurate picture of current species’ distributions and broad-scale diversity patterns but may also allow for more accurate past and future distribution projections. These projections could infer not only changes in latitudinal and longitudinal distributions, but also track suitable habitat conditions via changes in depth distribution and identify likely deep-sea climate refugia scenarios. |
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7. 09:30 VIRTUAL Half a Century of Global Decline in Oceanic Sharks and Rays. Nathan Pacoureau*, Department of Biological Sciences, Earth to Ocean Research Group, Simon Fraser University; Cassandra Rigby, Centre for Sustainable Tropical Fisheries and Aquaculture & College of Science and Engineering, James Cook University; Peter Kyne, Research Institute for the Environment and Livelihoods, Charles Darwin University; Richard Sherley, Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus; Henning Winker, Joint Research Centre (JRC), European Commission; John Carlson, NOAA National Marine Fisheries Service, Southeast Fisheries Science Center, Panama City Laboratory; Sonja Fordham, Shark Advocates International, The Ocean Foundation; Rodrigo Barreto, Centro Nacional de Pesquisa e Conservação da Biodiversidade Marinha do Sudeste e Sul do Brasil (CEPSUL), Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio); Daniel Fernando, Blue Resources Trust; Malcolm Francis, National Institute of Water and Atmospheric Research n.pacoureau@gmail.com
Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas. Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goals: the Living Planet Index (a measure of changes in abundance aggregated from 57 abundance time-series datasets for 18 oceanic shark and ray species) and the Red List Index (a measure of change in extinction risk calculated for all 31 oceanic species of sharks and rays). We find that, since 1970, the global abundance of oceanic sharks and rays has declined by 71% owing to an 18-fold increase in relative fishing pressure. This depletion has increased the global extinction risk to the point at which three-quarters of the species comprising this functionally important assemblage are threatened with extinction. Strict prohibitions and precautionary science-based catch limits are urgently needed to avert population collapse, avoid the disruption of ecological functions and promote species recovery. |