Browsing by Author "Tumolo, Benjamin B."

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Facilitation strength across environmental and beneficiary trait gradients in stream communities
(Wiley, 2023-08) Tumolo, Benjamin B.; Albertson, Lindsey K.; Daniels, Melinda D.; Cross, Wyatt F.; Sklar, Leonard L.
Ecosystem engineers modify habitats in ways that facilitate other community members by ameliorating harsh conditions. The strength of such facilitation is predicted to be influenced by both beneficiary traits and abiotic context. One key trait of animals that could control the strength of facilitation is beneficiary body size because it should determine how beneficiaries fit within and exploit stress ameliorating habitat modifications. However, few studies have measured how beneficiary body size relates to facilitation strength along environmental gradients. We examined how the strength of facilitation by net‐spinning caddisflies on invertebrate communities in streams varied along an elevation gradient and based on traits of the invertebrate beneficiaries. We measured whether use of silk retreats as habitat concentrated invertebrate density and biomass compared to surrounding rock surface habitat and whether the use of retreat habitat varied across body sizes of community members along the gradient. We found that retreats substantially concentrated the densities of a diversity of taxa including eight different Orders, and this effect was greatest at high elevations. Caddisfly retreats also concentrated invertebrate biomass more as elevation increased. Body size of invertebrates inhabiting retreats was lower than that of surrounding rock habitats at low elevation sites, however, body size between retreats and rocks converged at higher elevation sites. Additionally, the body size of invertebrates found in retreats varied within and across taxa. Specifically, caddisfly retreats functioned as a potential nursery for taxa with large maximal body sizes. However, the patterns of this taxon‐specific nursery effect were not influenced by elevation unlike the patterns observed based on community‐level body size. Collectively, our results indicate that invertebrates use retreats in earlier life stages or when they are smaller in body size independent of life stage. Furthermore, our analysis suggests that facilitation strength intensifies as elevation increases within stream invertebrate communities. Further consideration of how trait variation and environmental gradients interact to determine the strength and direction of biotic interactions will be important as species ranges and environmental conditions continue to shift.
Occupied and abandoned structures from ecosystem engineering differentially facilitate stream community colonization
(2019-05) Tumolo, Benjamin B.; Albertson, Lindsey K.; Cross, Wyatt F.; Daniels, Melinda D.; Sklar, Leonard S.
Ecosystem engineers transform habitats in ways that facilitate a diversity of species; however, few investigations have isolated short‐term effects of engineers from the longer‐term legacy effects of their engineered structures. We investigated how initial presence of net‐spinning caddisflies (Hydropsychidae) and their structures that provide and modify habitat differentially influence benthic community colonization in a headwater stream by conducting an in situ experiment that included three treatments: (1) initial engineering organism with its habitat modification structure occupied (hereafter caddisfly); (2) initial habitat modification structure alone (hereafter silk); and (3) a control with the initial absence of both engineer and habitat modification structure (hereafter control). Total invertebrate colonization density and biomass was higher in caddisfly and silk treatments compared to controls (~25% and 35%, respectively). However, finer‐scale patterns of taxonomy revealed that density for one of the taxa, Chironomidae, was ~19% higher in caddisfly compared to silk treatments. Additionally, conspecific biomass was higher by an average of 50% in silk treatments compared to controls; however, no differences in Hydropsyche sp. biomass were detected between caddisfly treatments and controls, indicating initially abandoned silk structures elevated conspecific biomass. These findings suggest that the positive effects of the habitat modification structures that were occupied for the entirety of the experiment may outweigh any potential negative impacts from the engineer, which is known to be territorial. Importantly, these results reveal that the initial presence of the engineer itself may be important in maintaining the ecological significance of habitat modifications. Furthermore, the habitat modifications that were initially abandoned (silk) had similar positive effects on conspecific biomass compared to caddisfly treatments, suggesting legacy effects of these engineering structures may have pertinent intraspecific feedbacks of the same magnitude to that of occupied habitat modifications. Elucidating how engineers and their habitat modifications differentially facilitate organisms will allow for a clearer mechanistic understanding of the extent to which animal engineers and their actions influence aspects of community organization such as colonization.
Retreat but no surrender: net-spinning caddisfly (Hydropsychidae) silk has enduring effects on stream channel hydraulics
(2020-02) Maquire, Zachary; Tumolo, Benjamin B.; Albertson, Lindsey K.
Animals and plants engineer their physical environment by building structures that create or modify habitat. Biotic effects on physical habitats can influence community composition, trophic dynamics, and ecosystem processes; however, the scales and mechanisms regulating the importance of biotic engineering effects are not well documented. We used a laboratory experiment with common and abundant silk net-spinning caddisflies (Trichoptera:Hydropsychidae) to investigate how biotic structures built in riverbeds influence fluid dynamics at micro spatial scales (1 cm) over 2 months. We made velocity measurements with acoustic doppler velocimetry around caddisfly silk structures to test how they influence flow velocity and whether these effects are maintained after the structure is abandoned. We found that caddisfly retreats reduced flow downstream by 85% and upstream by 17% compared to gravels without caddisfly retreats. We also found that experimentally abandoned caddisfly retreats could persist for at least 60 days, suggesting legacy effects of the structures. Although aquatic insects are rarely accounted for in hydrological models, our study suggests that small, but numerous caddisfly larvae could have substantial hydraulic effects. Future work could address variation in the magnitude and duration of biotic engineering among different silk-producing species, densities through space or time, and hydrologic regimes.
The ghosts of ecosystem engineers: Legacy effects of biogenic modifications
(Wiley, 2022) Albertson, Lindsey K.; Sklar, Leonard S.; Tumolo, Benjamin B.; Cross, Wyatt F.; Collins, Scott F.; Woods, H. Arthur
Ecosystem engineers strongly influence the communities in which they live by modifying habitats and altering resource availability. These biogenic changes can persist beyond the presence of the engineer, and such modifications are known as ecosystem engineering legacy effects. Although many authors recognize ecosystem engineering legacies, and some case studies quantify the effects of legacies, few general frameworks describe their causes and consequences across species or ecosystem types. Here, we synthesize evidence for ecosystem engineering legacies and describe how consideration of key traits of engineers improves understanding of which engineers are likely to leave persistent biogenic modifications. Our review demonstrates that engineering legacies are ubiquitous, with substantial effects on individuals, communities and ecosystem processes. Attributes that may promote the persistence of influential legacies relate to an engineer's traits, including its body size, life span and living strategy (individual, conspecific group or collection of multiple co-occurring species). Additional lines of inquiry, such as how the recipients respond (e.g. density or richness) or the mechanism of engineering (e.g. burrowing or structure building), should be included in future ecosystem engineering legacy research. Understanding patterns of these persistent effects of ecosystem engineers and evaluating the consequences of losing them is an important area of research needed for understanding long-term ecological responses to global change and biodiversity loss.
Top-down effects of an invasive omnivore: detection in long-term monitoring of large-river reservoir chlorophyll-a
(2018-10) Tumolo, Benjamin B.; Flinn, Micahel B.
Invasive species are capable of altering ecosystems through the consumption of basal resources. However, quantifying the effects of invasive species in large ecosystems is challenging. Measuring changes in basal resources (i.e., phytoplankton) at an ecosystem scale is an important and potentially translatable response vital to the understanding of how introduced species influence ecosystems. In this study, we analyzed patterns of early summer chlorophyll-a in a large-river reservoir in response to invasion of silver carp (Hypophthalmichthys molitrix). We used 25 years of ecological data from a 30-km reach of Kentucky Lake collected before and after silver carp establishment. We found significant decreases in chlorophyll-a within certain reservoir habitats since establishment of silver carp. Additionally, environmental and biological drivers of phytoplankton production showed no significant differences before and after invasion. These results suggest seasonal, and habitat-specific consumptive effects of invasive silver carp on an important basal food web resource. Further, our results convey the utility of long-term quantitative biological and physiochemical data in understanding ecosystem responses to elements of global change (i.e., species invasions). Importantly, the observed changes in the basal food web resource of Kentucky Lake may apply to other ecosystems facing invasion by silver carp (e.g., Laurentian Great Lakes). Our study offers insight into the mechanisms by which silver carp may influence ecosystems and furthers our understanding of invasive omnivores.
Toward spatio-temporal delineation of positive interactions in ecology
(2020-09) Tumolo, Benjamin B.; Calle, Leonardo; Anderson, Heidi E.; Briggs, Michelle A.; Carlson, Samuel P.; MacDonald, Michael J.; Reinert, James Holden; Albertson, Lindsey K.
Given unprecedented rates of biodiversity loss, there is an urgency to better understand the ecological consequences of interactions among organisms that may lost or altered. Positive interactions among organisms of the same or different species that directly or indirectly improve performance of at least one participant can structure populations and communities and control ecosystem process. However, we are still in need of synthetic approaches to better understand how positive interactions scale spatio-temporally across a range of taxa and ecosystems. Here, we synthesize two complementary approaches to more rigorously describe positive interactions and their consequences among organisms, across taxa, and over spatio-temporal scales. In the first approach, which we call the mechanistic approach, we make a distinction between two principal mechanisms of facilitation—habitat modification and resource modification. Considering the differences in these two mechanisms is critical because it delineates the potential spatio-temporal bounds over which a positive interaction can occur. We offer guidance on improved sampling regimes for quantification of these mechanistic interactions and their consequences. Second, we present a trait-based approach in which traits of facilitators or traits of beneficiaries can modulate their magnitude of effect or how they respond to either of the positive interaction mechanisms, respectively. Therefore, both approaches can be integrated together by quantifying the degree to which a focal facilitator's or beneficiary's traits explain the magnitude of a positive effect in space and time. Furthermore, we demonstrate how field measurements and analytical techniques can be used to collect and analyze data to test the predictions presented herein. We conclude by discussing how these approaches can be applied to contemporary challenges in ecology, such as conservation and restoration and suggest avenues for future research.