Biology subjects

Karatayev, V. A.

Publications and source records attributed to Karatayev, V. A..

7 recordsLinked to original sources

bioRxiv2023

An abundant future for quagga mussels in deep European lakes

Quagga mussels have expanded their range across the northern hemisphere in recent decades owing to their dispersal abilities, prolific reproduction rates, and broad ecological tolerances. Their remarkable capacity to filter particulates from the water column has had profound effects on inland aquatic ecosystems. In the North American Great Lakes, quagga mussel populations have increased inexorably since the late 1980s, but it remains unclear whether quagga mussels will follow a similar trajectory in Europe where they have appeared more recently. Here we apply knowledge from a 33-year quagga population monitoring effort in the North American lakes to predict future quagga populations in deep European lakes, where quaggas are quickly becoming a conspicuous part of the underwater landscape. We predict that quagga mussel biomass in Lakes Biel, Constance, and Geneva may increase by a factor of 9 - 20 by 2045. Like in North America, this increase may be characterized by a shift to larger individuals and deeper depths as the population matures. If realized, this rapid expansion of quagga mussels would likely drive the largest aquatic ecosystem change in deep European lakes since the eutrophication period of the mid-20th century.

ecology↗

bioRxiv2022

Acclimating to degraded environments: The social rationale for swift action on restoration

As environmental degradation progresses, economies and societies adapt to the loss of ecosystem services and public attention to degradation subsides. In systems experiencing such societal acclimation to degradation, net incentives for stakeholder mitigation peak during early degradation phases and subside over time. Using harmful algae blooms in western Lake Erie as a case study, we illustrate how declines in public attention and societal reliance on lake recreation (i.e., finding recreation alternatives) reduce the incentives for stakeholders to reduce pollution runoff (i.e., mitigation efforts throughout the watershed). We then analyze how acclimation can affect a broad array of conservation challenges by developing a general socio-ecological model of societal response to degradation. We find that delays in initiating stakeholder-driven mitigation efforts can exponentially prolong restoration projects. Furthermore, when alleviating intense degradation relies upon voluntary commitments by many individuals, windows of opportunity for mitigation can be very limited because feedback loops of societal adaptation doom late restoration efforts to failure and lock human-environment systems into degraded states. These windows of opportunity can be particularly narrow when a) stakeholder mitigation requires supportive public opinion or b) even modestly valuable alternative services are available in degraded ecosystems. In such cases, maintaining undegraded human-environment regimes may hinge on quickly initiating stakeholder mitigation movements and allocating limited government conservation funds soon after degradation begins instead of spreading mitigation efforts out over decades. Such initiatives, regardless of whether acclimation is slow or rapid in a given system, also greatly accelerate the pace of environmental restoration. Significance StatementAs societies acclimate to degraded environments, mitigation efforts that hinge on action by many stakeholders can erode. Developing a socio-ecological model of acclimation, we reveal how social and environmental processes intertwine to create alternative stable socio-ecological regimes, with either: 1) undegraded ecosystem states sustained by widespread mitigation adoption, or 2) degraded states where societies neither maintain nor continue relying on traditional, local ecosystem services. This dynamic places a premium on prompt mitigation efforts, which may face narrow opportunity windows to get started and avert degraded regimes in systems that rely on stakeholder-driven mitigation. Moreover, in any system requiring stakeholder action, societal acclimation will increase the importance of early action because decaying mitigation incentives exponentially lengthen restoration efforts.

ecology↗

bioRxiv2021

Serial invasions can disrupt the time course of ecosystem recovery

The impacts of species invasions can subside or amplify over time as ecosystems "adapt" or additional invaders arrive. These long-term changes provide important insights into ecosystem dynamics. Yet studies of long-term dynamics are rare and often confound species impacts with coincident environmental change. We synthesize many-decade time-series across ecosystems to resolve shared changes in seven key features following invasion by quagga and zebra mussels, two widespread congeners that re-engineer and increasingly co-invade freshwaters. Six polymictic shallow lakes with long-term data sets reveal remarkably similar trends, with the strongest ecosystem impacts occurring within 5-10 years of zebra mussel invasion. Surprisingly, plankton communities then exhibited a partial, significant recovery. This recovery was absent, and impacts of initial invasion amplified, in lakes where quagga mussels outcompeted zebra mussels and more completely depleted phytoplankton. Thus, invasion impacts subside over time but can amplify with serial introductions of competing, even closely similar, taxa.

ecology↗

bioRxiv2020

Species heterogeneity in food webs can reduce the potential for alternative stable states

Alternative stable ecosystem states are possible under the same environmental conditions in many models of 2-3 interacting species and an array of feedback loops. However, multi-species food webs might dissipate the feedbacks that create alternative stable states through species-specific traits and feedbacks. To test this potential, we develop a manyspecies model of consumer-resource interactions with two classes of feedbacks: specialized feedbacks where individual resources become unpalatable at high abundance, or aggregate feedbacks where overall resource abundance reduces consumer recruitment. We quantify how trophic interconnectedness and species differences in demography affect the potential for either feedback to produce alternative stable states dominated by consumers or resources. We find that alternative stable states are likely to happen in many-species food webs when aggregate feedbacks or lower species differences increase redundancy in species contributions to persistence of the consumer guild. Conversely, specialized palatability feedbacks with distinctive species roles in consumer guild persistence reduce the potential for alternative states but increase the likelihood that losing vulnerable consumers cascades into a food web collapse at low stress levels, a dynamic absent in few-species models. Altogether, among-species trait variation can limit the set of processes that create alternative stable states and impede consumer recovery from disturbance.

ecology↗

bioRxiv2019

Grazer behavior can regulate large-scale patterns of community states

Ecosystem patterning can arise from environmental heterogeneity, biological feedbacks that produce multiple persistent ecological states, or their interaction. One source of feed-backs is density-dependent changes in behavior that regulates species interactions. By fitting state-space models to large-scale ([~]500km) surveys on temperate rocky reefs, we find that behavioral feedbacks best explain why kelp and urchin barrens form either reef-wide patches or local mosaics. Best-supported models in California include feedbacks where starvation intensifies grazing across entire reefs create reef-scale, alternatively stable kelp- and urchin-dominated states (32% of reefs). Best-fitting models in New Zealand include the feedback of urchins avoiding dense kelp stands that can increase abrasion and predation risk, which drives a transition from shallower urchin-dominated to deeper kelp-dominated zones, with patchiness at 3-8m depths with intermediate wave stress. Connecting locally-studied processes with region-wide data, we highlight how behavior can explain community patterning and why some systems exhibit community-wide alternative stable states.

ecology↗

bioRxiv2019

Advection and habitat loss interactively reduce persistence: maintaining threatened riverine populations while restoring natural flow regimes

Modification of flow regimes and habitat degradation are the strongest, most common, and often co-occurring human activities affecting riverine populations. Ongoing efforts to restore peak flow events found under pristine flow regimes could increase advection-driven dispersal for many species. In rivers with extensive habitat loss, increased advection could transport individuals from remnant populations into degraded downstream areas, causing restored flow regimes to decrease persistence of threatened species. To resolve the capacity for such washout effects across imperiled taxa, we evaluate population growth in spatial matrix models of insect, fish, and mollusc taxa experiencing advective dispersal and either long-term habitat loss or temporary disturbances. As a case study to quantify advective dispersal in threatened species, we use intensive mark-recapture methods in a Rio Grande population of the federally endangered unionid mussel Texas horhshell (Popenaias popeii). Among unionids, the most threatened freshwater taxa of North America, we find high levels of annual downstream emigration (16-51%) of adult P. popeii, concomitant with strong immigration from upstream habitats. For different taxa experiencing such advective dispersal during specific life stages, our population model shows that washout effects strongly reduce population recovery under high levels of habitat loss. Averting this negative consequence of restoring hydrology requires simultaneously restoring or protecting long, contiguous stretches of suitable habitats. Across taxa in heavily impacted systems, we suggest integrating hydrodynamic studies and field surveys to detect the presence of advective dispersal and prioritize areas for habitat restoration to enhance population persistence.

ecology↗

bioRxiv2019

At what spatial scales are alternative stable states relevant in highly interconnected ecosystems?

Whether ecosystems recover from disturbance depends on the presence of alternative stable states, which are theoretically possible in simple models of many systems. However, definitive empirical evidence for this phenomenon remains limited to demographically closed ecosystems such as lakes. In more interconnected systems such as temperate rocky reefs, the local relevance of alternative stable states might erode as immigration overwhelms local feedbacks and produces a single stable state. At larger spatial scales, dispersal might counter localized disturbance and feedbacks to synchronize states throughout a region. Here, we quantify how interconnectedness affects the relevance of alternative stable states using dynamical models of California rocky reef communities that incorporate observed environmental stochasticity and feedback loops in kelp-urchin-predator interactions. Our models demonstrate the potential for localized alternative states despite high interconnectedness likely due to feedbacks affecting dispersers as they settle into local communities. Regionally, such feedbacks affecting settlement can produce a mosaic of alternative stable states that span local (10-20km) scales despite the synchronizing effect of long-distance dispersal. The specific spatial scale and duration of each state predominantly depend on the scales of environmental variation and on local dynamics (here, fishing). Model predictions reflect observed scales of community states in California rocky reefs and suggest how alternative states co-occur in the wide array of marine and terrestrial systems with settlement feedbacks.

ecology↗