This is a general session covering topics in Aquatic Invasion Ecology.
Lead Organizer: Reuben Keller, Loyola University Chicago (rkeller1@luc.edu)
Presentations
09:00 AM
COEXISTENCE OF INVASIVE RUSTY (FAXONIUS RUSTICUS) AND RED SWAMP (PROCAMBARUS CLARKII) CRAYFISH IN AN URBAN WATERWAY (8418)
Primary Presenter: Reuben Keller, Loyola University Chicago (rkeller1@luc.edu)
Red swamp (Procambarus clarkii) and rusty (Faxonius rusticus) crayfish are two highly invasive and widespread species. A main impact of each species is the extirpation of native crayfishes from the habitats that they invade. In the North Shore Channel (NSC) of the Chicago River these two species have overlapping populations. We have investigated the mechanisms that allow these species to overlap. In lab experiments red swamp crayfish exhibited more aggressive behaviors than rusty (p<0.01), leading to a hypothesis that red swamp would win competition for food. In experiments, red swamp crayfish won 66% of competition trials for a single food item. Next, we hypothesized that the aggression of red swamp crayfish would lead to higher susceptibility to predation by fishes, which are the main crayfish predator in this system. We have used lavage to retrieve stomach contents from 545 fishes in the NSC. We found crayfish in the stomachs of 90 fish, and 88 (98%) of these crayfish were red swamp, while only 2 (2%) were rusty crayfish. Finally, we hypothesized that the higher aggression of red swamp crayfish would lead to them having a higher trophic level in the zone where these species overlap. Stable isotope analysis showed the opposite; rusty crayfish have a higher trophic level than red swamp crayfish in the zone of overlap (t-test, p<0.05). Our results show that red swamp crayfish are predated at much higher rates than rusty crayfish, and that this may offset an advantage of red swamp that allows for coexisting populations of these highly invasive species.
09:15 AM
EFFECT OF ECOSYSTEM SIZE AND POPULATION PRODUCTIVITY ON FEASIBILITY OF GENETIC BIOCONTROL FOR INVASIVE SPECIES (8334)
Primary Presenter: Ellie Wallace, Utah State University (ellie.wallace@usu.edu)
Population resistance and resilience to disturbance are typically considered beneficial attributes, yet present substantial challenges to invasive species control efforts. The use of Trojan Y Chromosomes (TYC) is increasingly being considered for invasive species control, but has largely been limited to small ecosystems with small-bodied and short-lived species. Controlling large-bodied and long-lived species in large ecosystems presents a greater challenge. Here, we use a simulation modeling approach to characterize the effectiveness of TYC stocking for biocontrol across a range of ecosystem sizes and population productivities, representing a range of population resistance and resilience conditions. Our results indicate that more productive populations are able to persist longer than less productive populations under the same YY stocking intensity, and that this relationship intensifies with increasing ecosystem size. We identify threshold levels of stocking intensity below which control efforts are ineffective, and find that stocking YY- females is generally more effective than stocking YY-males. Finally, coupling TYC stocking with concurrent mechanical removal efforts increases control program efficacy. Given increasing interest in using TYC to control invasive species, it is imperative to recognize the ecological conditions under which TYC strategies are likely to be effective. The thresholds identified herein can help managers determine whether TYC stocking represents a feasible approach given their specific system, population productivity, and available resources.
09:30 AM
DETERMINING THE PRESENCE OF NON-NATIVE AQUATIC SPECIES IN RECREATIONAL BOAT HARBORS IN CHICAGO, ILLINOIS (8042)
Primary Presenter: Alex Quebbeman, Loyola University Chicago (aquebbeman@luc.edu)
The spread of aquatic invasive species (AIS) creates ecological and economic problems that are often long-term and difficult to manage. The movement of recreational boats is a well-known vector for unintentional AIS transport in the Great Lakes region. An area with particularly high recreational boat activity is Chicago, which has a high population density, harbors on Lake Michigan, and several boat ramps that allow overland access to many other waterbodies. Because of this, Chicago’s recreational harbors may be a hub for the spread of AIS. In the summer of 2023, I sampled nine recreational harbors in the Chicago region to identify the presence and abundance of non-native macrophytes and macroinvertebrates. Macrophyte sampling at each harbor was conducted via 10 tosses of a doubled-sided rake, and macroinvertebrates were sampled with rock bags, Hester-Dendy samplers, and scraping. Non-native macrophytes were present at seven harbors and included Myriophyllum spicatum (n=5 harbors), Nitellopsis Obtusa (n=2), and Potamogeton crispus (n=1). These are the first records of N. obtusa in the Chicago region, and also new records for M. spicatum and P. crispus. Macroinvertebrate sorting is ongoing. My results show that recreational harbors can be important sites for the establishment of new AIS. In particular, N. obtusa is a high priority species that had not previously been identified in the Chicago region. Its establishment in harbors means that it is likely to spread further on boats traveling on water and overland.
09:45 AM
IMPACTS OF REMOVAL OF INVASIVE CRAYFISH PROCAMBARUS CLARKII ON MACROPHYTES AND MACROINVERTEBRATES IN AN URBAN, FLOWING SYSTEM (7850)
Primary Presenter: Rachel Egly, Loyola University Chicago (regly@luc.edu)
Procambarus clarkii (red swamp crayfish) is a species of great concern in the Laurentian Great Lakes area due to the recent discovery of established populations in inland and Great Lakes-connected waters. In other systems, introduction of P. clarkii has resulted in reduced abundance of macrophytes and macroinvertebrates and increased competition with native crayfish species. A high-density population is established in the North Shore Channel of the Chicago Area Waterway System (CAWS). The CAWS is a system of canals that connects Lake Michigan to the Mississippi River Basin. We have implemented intensive trapping and removal of P. clarkii to reduce population size in this system. Our goals in this work are to reduce population size so that the chance of spread is lessened and to reduce ecosystem effects. We have conducted intensive trapping of the population during six consecutive summers (2018-2023) using baited traps. We conducted macrophyte and macroinvertebrate sampling in the summer of 2023 to determine species density and richness in two reaches where we intensively trap and remove P. clarkii. Results from these reaches were compared to a control reach where crayfish are not removed. We found that both macrophyte species density (p << 0.01) and species richness (p << 0.01) were significantly greater in the control reach compared to the removal reaches. Macroinvertebrate species density and richness were not significantly different in the control reach compared to the removal reaches. Our study demonstrates that control efforts of invasive crayfish such as P. clarkii can reduce population size but that ecosystem outcomes can vary.
10:00 AM
ECOLOGICAL IMPACTS OF A RESILIENT CORAL IN HONOLULU HARBOR (8178)
Primary Presenter: Madelief Schelvis, University of Hawaiʻi at Mānoa (madelief@hawaii.edu)
Harbor Porites is an unusually resilient coral species of uncertain origin and taxonomy found in high abundance in Honolulu Harbor. The harbor is an inhospitable environment for most corals, with high levels of pollution and human activity. Harbor Porites is of particular interest to conservationists, both for its ability to colonize hostile environments and encourage reef growth as a pioneer species, and for the threats it may pose as a dominant species that may invade reefs beyond the harbor. This project aims to investigate the ecological impacts of this species by characterizing its competitive abilities. Fragments of harbor Porites were placed in direct contact with fragments of five other coral species and were observed for signs of aggression along the zone of contact, noting mesenterial filaments, sweeper tentacles, and tissue mortality. Preliminary results categorize harbor Porites as moderately aggressive, dominating over some species but subordinate to others. Further experiments and field surveys will investigate whether the presence of this species may promote reef growth by encouraging larval settlement of other corals, and whether its dominance in the harbor may limit the growth of algae and sponges that may otherwise prevent coral growth. Corals form the basis of some of the most ecologically, culturally, and economically significant ecosystems on Earth, valued at over $2 trillion. With coral reefs degrading under anthropogenic sources of stress, factors underlying reef resilience are of particular interest to managers and policymakers.
10:15 AM
MICROPLASTIC ACCUMULATION IN INVASIVE RED SWAMP CRAYFISH (PROCAMBARUS CLARKII) IN A HIGHLY URBANIZED RIVER (8103)
Primary Presenter: Tava Oosterbaan, Loyola University Chicago (toosterbaan@luc.edu)
Microplastic pollution in freshwater ecosystems causes a range of negative impacts, including accumulating within aquatic organisms. Microplastics may act as physical blockages and can induce a range of inflammatory and immune responses in organisms. Red swamp crayfish (Procambarus clarkii) is a high-profile invasive species that is established widely around the world. Three studies have investigated microplastic presence in this species, and none have used a highly polluted waterway as a study site. We have investigated levels of microplastic in P. clarkii in the North Shore Channel of the Chicago River, which has some of the highest levels of microplastics ever recorded in an aquatic system. The O’Brien Wastewater Treatment Plant is the main source of microplastic pollution in the river. During summer 2023 we collected 16 P. clarkii from above, and 38 from below, the treatment plant (n=54). We also collected water (n=20) and sediment samples (n=30). Our initial analysis is dissecting a subset of crayfish (n=10) to look at microplastic loads in the GI tract, hepatopancreas, tail tissue, ovaries, and the remaining exoskeleton and tissues. Initial results show that microplastics can be found in at least the GI tract, hepatopancreas, and ovaries. From the ovaries of five female red swamp crayfish we retrieved 17.8 ± 8.04 (mean ± s.d.) microplastic particles. Our results show that microplastic pollution is not only entering crayfish in this urban waterway but that it is accumulating in multiple organs. Full results for all crayfish will be available and presented.
CS04 - Aquatic Invasion Ecology
Description
Time: 9:00 AM
Date: 5/6/2024
Room: Hall of Ideas F