Session 45: Ichthyology EcologyRoom: Ballroom 111C2022-07-31 10:00 - 12:00 |
| Moderator: Paul Spruell |
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1. 10:00 Feeding habits of Moncholo Hoplias malabaricus in the Cienaga Grande de Lorica, Colombia. José D. Petro-Blanquicet, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Lucía M. Herrera-Chimá, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Jesús Vargas González Vargas-González, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Juan J. Hernández-Correa, SEPEC; Glenys Tordecilla-Petro, 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; Ángel L. Martínez-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 colaya@correo.unicordoba.edu.co
To evaluate the feeding habits of Moncholo Hoplias malabaricus in the Cienaga Grande de Lorica, Colombia, we analyzed 366 stomachs of individuals collected between January and December 2018, with total length (TL) and total weight (TW) ranged between 18.9-38.1 cm TL and 62.0-667.0 grams, respectively. The stomach content was evaluate using the proportion of empty stomachs, grade of digestion, frequency of occurrence, numerical frequency and gravimetry. The trophic niche, the equity index and the relative importance index were also estimated. It was found that almost 2/3 (66.4%) of the studied stomachs were empty, 46.5% of the food consumed was half digested and three food groups were identified in the diet of the species under study: Fish, Plant material and Detritus. Fish, composed of Cachana Cyrtocharax atratoensis, Cocobolo Andinoacara sp., Yalúa Cyphocharax magdalenae and fish remains (fins, scales, spines, skeletal structures) was the most frequent food group (95.9%), most abundant (83.8%) and with the highest composition by weight (98.8%), becoming the main food and of greater relative importance in the diet of the species under study; while Plant Material and Detritus are circumstantial and of low relative importance. The Moncholo has a narrow trophic spectrum, maintains its food preferences as it grows and through the hydrological cycle of the Cienaga Grande de Lorica, which suggests that it is a fish with a stenophagic diet and piscivorous feeding habits. |
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2. 10:15 Feeding ecology of Yellow Mojarra Caquetaia kraussii in the Cienaga Grande de Lorica, Colombia. Lina M. Ramos-Morón, Fishery Biology Research Laboratory-FBRL, Department of Aquatic Sciences. University of Cordoba; Martha M. Lerma-Díaz, 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; 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 colaya@correo.unicordoba.edu.co
To evaluate the feeding ecology of Yellow Mojarra Caquetaia kraussii in the Cienaga Grande de Lorica, Colombia, we analyzed 427 stomachs of individuals collected between January and December 2017, with total length (TL) and total weight (TW) ranged between 13.1-21.0 cm and 34.3-150.0 grams, respectively. The stomach content was evaluate using the proportion of empty stomachs, grade of digestion, frequency of occurrence, numerical frequency and gravimetry. The trophic niche, the equity index and the relative importance index were also estimated. A little more than half of the stomachs studied were empty (54.8%), while most of the food consumed was half digested (75.9%), and five food groups were identified in the diet: Fish, vegetable Rests, Insects, unidentified organic matter and Others groups. Fishes was the most common group (73.6%), the most abundant group (58.4%), the greatest group composition in weight (93.0%) and the main food in their diet. The Yellow Mojarra has a narrow trophic spectrum with a greater participation of fish, which maintains its food preferences as it grows, except in larger sizes, which suggests that its diet is carnivorous with a piscivorous tendency. |
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3. 10:30 Response of Southern Lake Michigan Nearshore Fish Assemblage (1984-2016) to Oligotrophication and Multiple Stressors: Comparison to Other Systems. Christopher Malinowski*, Department of Forestry and Natural Resources, Purdue University; Tomas Höök, Department of Forestry and Natural Resources, Purdue University; Jason Doll, Freshwater Ecology Center, Department of Biology, Francis Marion University cmali156@gmail.com
Many coastal ecosystems, including those of the Laurentian Great Lakes and Florida’s estuaries, suffer from various natural and anthropogenic stressors. Given that multiple stressors often concomitantly impact ecosystems, it may be difficult to disentangle which stressors are most influential. Upper trophic level communities, such as fish assemblages, can provide insights to the influence of diverse stressors as they may integrate cumulative effects over the long-term and also reflect responses of lower trophic levels. We used multivariate analyses and assemblage indices to investigate long-term (1984-2016) patterns in nearshore fish assemblages indexed via annual trawling in the Indiana waters of southern Lake Michigan. Based on observations from other regions of the Great Lakes, we expected that oligotrophication, due to reduced nutrient loading and filtering by invasive dreissenid mussels, would have a strong influence on the fish assemblage. Consistent with this expectation, overall abundance and richness of the assemblage declined over time. However, contrary to observations in other regions there was no overall evidence of species tolerant to more eutrophic conditions being replaced by species more sensitive to eutrophic conditions. While increased numbers of invasive species added species to the system, overall species richness and native species richness declined. Additional work on fish species and fish assemblages in the St Lucie estuary, Florida USA, a eutrophic estuary with degraded water quality and frequent episodes of harmful algal blooms, will reveal resulting impacts of rainfall and discharges across wet and dry seasons. |
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4. 10:45 Detection of a Nematode Parasite in an Introduced Population of Brook Stickleback. Paul Spruell*, Eastern Washington University; Carissa Simpson, Eastern Washington University; Neville Magone, Eastern Washington University pspruell@ewu.edu
The enemy release hypothesis suggests that introduced species may be freed from their natural predators and parasites, allowing them to increase in number and outcompete native species. Populations of introduced species that are exposed to parasites after establishment represent a potential system in which to study the enemy release hypothesis. Brook Stickleback (Culaea inconstans) in eastern Washington are one such species. Brook Stickleback were first detected in the wetlands of Turnbull Wildlife Refuge in 1999 and have subsequently colonized most of the refuge wetlands. In 2016, an internal nematode parasite was observed free (not encysted) within the pericardial cavity of several stickleback specimens. Periodic surveys of the refuge since 2016 have documented the presence of the parasite in a single waterbody, Middle Pine Pond. We used DNA sequencing of five regions within the mitochondrial genome to identify the parasite as a member of the Contracaecum multipapillatum species complex. We have also recorded an increasing trend in both the prevalence of parasites (proportion of individuals infected) and the severity of infection (number of nematodes per infected individual). Infected fish are also statistically smaller than parasite-free fish. Despite these observations, the relative abundance of Brook Stickleback in Middle Pine Pond exceeds that of all other wetlands surveyed. Continued monitoring will be necessary to determine if the parasite has not yet reached sufficient levels to be a limiting factor on Brook Stickleback populations or if parasite infection does not reduce reproductive success in Middle Pine Pond. |
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5. 11:00 Habitat Associations of Fishes Across a Gradient of Pool Size and Structure in an Ozark River. David Adams*, University of Central Arkansas; Reid Adams, University of Central Arkansas; Ginny Adams, University of Central Arkansas; David Mitchell, Ozarka College davidreidadams@icloud.com
Streams in the Ozark Mountains have experienced an extended period of gravel aggradation, which has resulted in stream shallowing along with changes in substrate composition. These changes in stream geomorphology have likely had an impact on fish community structure; however, due to sampling limitations, few data are available on fishes inhabiting pools, particularly in deep, non-wadable habitats. We hypothesized deeper pools in the Kings River with boulder and wood would be optimal habitat for many large-bodied species. We conducted snorkel surveys at 20 pool/run reaches, with four to eight snorkelers moving from downstream to upstream, to determine relative abundances of 14 target fish species/life stages. Community assemblage structure varied across reaches along a gradient of habitat variables with some reaches being deeper with higher percent boulder substrate and others shallower with lower boulder. Associations between habitat variables and individual species/life stages abundances were evaluated using regression tree analyses. For example, higher relative abundances of quality-sized Smallmouth Bass (Micropterus dolomieu) were associated with boulder volumes equal to and greater than 36.93 m3, whereas higher relative abundances of juvenile and young-of-year M. dolomieu were associated with average depths less than 0.43 m. Increased depths were positively associated with 11 of the 14 target species/life stages examined. Our data highlight the value of large, deep pools for maintenance of fish diversity in the Kings River and the potential impacts of continued gravel aggradation. |
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6. 11:15 Pacific Lamprey facilitate juvenile salmonids and Foothill Yellow-legged Frogs. Philip Georgakakos, University of California; Gabriel Rossi, University of California; Sarah Kupferberg*, University of California; Abel Brumo, Stillwater Sciences; Mary Power, University of California skupferberg@gmail.com
In the Pacific Northwest, great numbers of Pacific Lamprey (Entosphenus tridentatus) once migrated into coastal rivers, where they mobilized and rearranged large volumes of sediment to construct nests for spawning. Such bioturbation is the occasion for numerous ecological interactions. In California’s Eel River we investigated how lamprey redd construction influences (1) drift of stream invertebrates, (2) foraging of juvenile steelhead (Oncorhynchus mykiss), and (3) hydraulic conditions for breeding Foothill Yellow-legged Frogs (Rana boylii). We found an average of 113% more invertebrates in drift samples downstream of lamprey activity than in lateral positions, and 125% higher invertebrate biomass concentration. Juvenile steelhead made an average of 76% more foraging attempts when drift feeding downstream of redd-building lamprey. Bioenergetics models indicated these locations were more profitable for fish growth than adjacent areas. Timing and location of lamprey spawning also frequently coincided with egg deposition by frogs at their lek sites. Frog egg masses attached to rocks inside completed redds benefitted from the flow refuge, which decreased scour risk. Added depth kept clutches submerged as spring flows receded. Salmonid fry also held positions in the low-velocity areas within redd excavations. Our findings emphasize benefits of lamprey to other fauna beyond delivering ocean-derived nutrients and energy to river ecosystems. The bounty of lamprey, which continues to be important to Native Americans for subsistence, ceremonial, and medicinal purposes, has the potential to facilitate imperiled salmonids and frogs. We stress the need to continue current efforts to restore lamprey to plentiful abundance across their historic range. |
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7. 11:30 Feeding Ecology of Leptocephali in the Satsunan Area, Southern Japan. Akinori Minagawa*, Kagoshima University; Toru Kobari, Kagoshima University; Junya Hirai, Atmosphere and Ocean Research Institute; Satoru Jinno, Ehime Prefectural Fisheries Experimental Station; Kazuhiro Shiozaki, Kagoshima University; Mutsuo Ichinomiya, Prefectural University of Kumamoto; Tomohiro Komorita, Prefectural University of Kumamoto; Gen Kume, Kagoshima University mina.akinori@gmail.com
Information on the feeding ecology of leptocephali, including Japanese eels, is essential for the aquaculture of anguilliform fishes. Leptocephali were thought to feed on marine snow, but the details of their diet are unknown. In this study, we applied multiple approaches to gain insights into the feeding ecology of leptocephali: electron microscopic examination, DNA metabarcoding analysis for gut contents, and stable isotope analysis. Samples were collected by an Ocean Research Institute net(diameter: 160cm; mesh size: 335??) from the Kuroshio Current and the adjacent waters in 2020-2021. A total of 43 leptocephali (Gnathophis spp., Gymnothorax minor, Dysomma spp., Muraenesox spp., Saurenchelys spp., Heteroconger spp., Congrinae spp., Ophichthinae spp., Nettastomatidae spp.) were used for these analyses. DNA metabarcoding analysis detected a high percentage of copepods (1.7-97%) and krills (9-92%), also contained various taxonomic groups in the gut contents. Stable isotope analysis showed that fecal pellets of calanoid copepods would be a main source of nutrition. By electron microscopic observations, particles that would have originated from fecal pellets of zooplankton were confirmed in gut of all leptocephali with amorphous content (n=13). Our data strongly suggest that leptocephali would selectively feed on the fecal pellets of zooplankton such as copepods in marine snow. |
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8. 11:45 Evolutionary Convergence: Widespread and Sometimes Remarkable. Kirk Winemiller*, Texas A&M University k-winemiller@tamu.edu
What exactly is convergent evolution, and how can we recognize it? Broadly defined, convergence is when members of two or more phylogenetically divergent lineages, having accumulated divergent traits (phenotypes), subsequently evolve similar traits, often with similar functions. These convergent phenotypes can be viewed with regards to different levels of biological organization (biochemistry, physiology, morphology, behavior, whole organism), different functions related to different niche dimensions (body plan/habitat use, physiology, trophic, life history, defense), and varying degrees of prior trait differentiation (same vs. different precursor trait). Review of evidence from fishes indicates that convergence usually involves only one or few traits and few niche dimensions. Evidence of convergence, therefore, is widespread. However, convergence sometimes involves multiple traits and niche dimensions, and these cases are recognized as remarkable convergence. Examples of remarkable convergence capture the imagination but also bias our perception of convergence, which, in fact, is nearly ubiquitous in contemporary and past biotas. In this light, perhaps equally remarkable are lineages that possess unique traits and trait combinations, often with unique functions for specialized niches. This talk will review evidence, mostly from fishes, for varying degrees of trait and niche convergence in relation to five niche dimensions. Recognition of subtle forms of convergence (i.e., unremarkable convergence) implies that natural physical and biochemical constraints result in widespread repeated evolution of certain traits and trait combinations with similar functions. |