July 2024
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28 Reads
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July 2024
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28 Reads
January 2024
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167 Reads
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7 Citations
Proceedings of the National Academy of Sciences
Cross-ecosystem subsidies are critical to ecosystem structure and function, especially in recipient ecosystems where they are the primary source of organic matter to the food web. Subsidies are indicative of processes connecting ecosystems and can couple ecological dynamics across system boundaries. However, the degree to which such flows can induce cross-ecosystem cascades of spatial synchrony, the tendency for system fluctuations to be correlated across locations, is not well understood. Synchrony has destabilizing effects on ecosystems, adding to the importance of understanding spatiotemporal patterns of synchrony transmission. In order to understand whether and how spatial synchrony cascades across the marine-terrestrial boundary via resource subsidies, we studied the relationship between giant kelp forests on rocky nearshore reefs and sandy beach ecosystems that receive resource subsidies in the form of kelp wrack (detritus). We found that synchrony cascades from rocky reefs to sandy beaches, with spatiotemporal patterns mediated by fluctuations in live kelp biomass, wave action, and beach width. Moreover, wrack deposition synchronized local abundances of shorebirds that move among beaches seeking to forage on wrack-associated invertebrates, demonstrating that synchrony due to subsidies propagates across trophic levels in the recipient ecosystem. Synchronizing resource subsidies likely play an underappreciated role in the spatiotemporal structure, functioning, and stability of ecosystems.
August 2023
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135 Reads
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8 Citations
Spatial synchrony, the tendency for populations across space to show correlated fluctuations, is a fundamental feature of population dynamics, linked to central topics of ecology such as population cycling, extinction risk, and ecosystem stability. A common mechanism of spatial synchrony is the Moran effect, whereby spatially synchronized environmental signals drive population dynamics and hence induce population synchrony. After reviewing recent progress in understanding Moran effects, we here elaborate a general theory of how Moran effects of different environmental drivers acting on the same populations can interact, either synergistically or destructively, to produce either substantially more or markedly less population synchrony than would otherwise occur. We provide intuition for how this newly recognized mechanism works through theoretical case studies and application of our theory to California populations of giant kelp. We argue that Moran interactions should be common. Our theory and analysis explain an important new aspect of a fundamental feature of spatiotemporal population dynamics.
May 2023
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72 Reads
Spatial synchrony, the tendency for populations across space to show correlated fluctuations, is a fundamental feature of population dynamics, linked to central topics of ecology such as population cycling, extinction risk, and ecosystem stability. A common mechanism of spatial synchrony is the Moran effect, whereby spatially synchronized environmental signals drive population dynamics and hence induce population synchrony. After reviewing recent progress in understanding Moran effects, we here elaborate a general theory of how Moran effects of different environmental drivers acting on the same populations can interact, either synergistically or destructively, to produce either substantially more or markedly less population synchrony than would otherwise occur. We provide intuition for how this newly recognized mechanism works through theoretical case studies and application of our theory to California populations of giant kelp. We argue that Moran interactions should be common. Our theory and analysis explain an important new aspect of a fundamental feature of spatiotemporal population dynamics.
September 2022
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204 Reads
Understanding intraspecific variation in habitat use, particularly of long-lived fishes across multiple life history stages, is core to improved conservation management. Here, we present results from a synthesis of acoustic telemetry data for sub-adult and adult white sturgeon (Acipenser transmontanus) from 2010 to 2017 in the San Francisco Estuary and Sacramento River ecosystems. We focused primarily on uncovering spatial patterns of inferred habitat occupancy across life stages, and on linking habitat use to extant anthropogenic threats. We found substantial differences in habitat use across individuals and over time that was related to fish size classes defined relative to the slot limit (102-152 cm) used to regulate recreational fishing. However, differences in habitat use were not explained by fish sex or water year flow conditions. We also estimated indices of overall exposure for two major threats: capture by anglers and habitat modification. Fish of harvestable size were detected less often than others in areas where many are caught. Future monitoring and management of white sturgeon might benefit from examining multiple phases of white sturgeon life history. For example, additional tracking studies could improve our understanding of juvenile habitat use, adult survival rates, patterns of anadromy, and cross-basin habitat utilization.
June 2022
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261 Reads
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21 Citations
Ecology Letters
Spatial synchrony is a ubiquitous and important feature of population dynamics, but many aspects of this phenomenon are not well understood. In particular, it is largely unknown how multiple environmental drivers interact to determine synchrony via Moran effects, and how these impacts vary across spatial and temporal scales. Using new wavelet statistical techniques, we characterised synchrony in populations of giant kelp Macrocystis pyrifera, a widely distributed marine foundation species, and related synchrony to variation in oceanographic conditions across 33 years (1987–2019) and >900 km of coastline in California, USA. We discovered that disturbance (storm‐driven waves) and resources (seawater nutrients)—underpinned by climatic variability—act individually and interactively to produce synchrony in giant kelp across geography and timescales. Our findings demonstrate that understanding and predicting synchrony, and thus the regional stability of populations, relies on resolving the synergistic and antagonistic Moran effects of multiple environmental drivers acting on different timescales. Spatial synchrony is a ubiquitous feature of population dynamics, but it is largely unknown how multiple environmental drivers interact to determine synchrony via Moran effects, and how these impacts vary across spatial and temporal scales. Using new wavelet statistical techniques, we characterized synchrony in populations of giant kelp, a widely distributed marine foundation species, and related synchrony to variation in oceanographic conditions. We discovered that disturbance and resources—underpinned by climatic variability—act individually and interactively to produce synchrony across geography and timescales, demonstrating that predicting regional population stability relies on resolving the synergistic and antagonistic Moran effects of multiple environmental drivers acting on different timescales.
June 2022
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93 Reads
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9 Citations
Understanding movement patterns of anadromous fishes is critical to conservation and management of declining wild populations and preservation of habitats. Yet, the duration of observations for individual animals can constrain accurate descriptions of movements. In this study, we synthesized over a decade (2006–2018) of acoustic telemetry tracking observations of green sturgeon (Acipenser medirostris) in the Sacramento River system to describe major anadromous movement patterns. We observed that green sturgeon exhibited a unimodal in‐migration during the spring months but had a bimodal distribution of out‐migration timing, split between an “early” out‐migration (32%) group during May–June, or, alternatively, holding in the river until a “late” out‐migration (68%), November–January. Focusing on these out‐migration groups, we found that river discharge, but not water temperature, may cue the timing of migration and that fish showed a tendency to maintain out‐migration timing between subsequent spawning migration events. We recommend that life history descriptions of green sturgeon in this region reflect the distinct out‐migration periods described here. Furthermore, we encourage the continued use of biotelemetry to describe migration timing and life history variation, in not only this population but also other green sturgeon populations and other species.
March 2022
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182 Reads
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11 Citations
The spatial distribution of dengue and its vectors (spp. Aedes) may be the widest it has ever been, and projections suggest that climate change may allow the expansion to continue. However, less work has been done to understand how climate variability and change affects dengue in regions where the pathogen is already endemic. In these areas, the waxing and waning of immunity has a large impact on temporal dynamics of cases of dengue haemorrhagic fever. Here, we use 51 years of data across 72 provinces and characterise spatiotemporal patterns of dengue in Thailand, where dengue has caused almost 1.5 million cases over the last 30 years, and examine the roles played by temperature and dynamics of immunity in giving rise to those patterns. We find that timescales of multiannual oscillations in dengue vary in space and time and uncover an interesting spatial phenomenon: Thailand has experienced multiple, periodic synchronisation events. We show that although patterns in synchrony of dengue are similar to those observed in temperature, the relationship between the two is most consistent during synchronous periods, while during asynchronous periods, temperature plays a less prominent role. With simulations from temperature-driven models, we explore how dynamics of immunity interact with temperature to produce the observed patterns in synchrony. The simulations produced patterns in synchrony that were similar to observations, supporting an important role of immunity. We demonstrate that multiannual oscillations produced by immunity can lead to asynchronous dynamics and that synchrony in temperature can then synchronise these dengue dynamics. At higher mean temperatures, immune dynamics can be more predominant, and dengue dynamics more insensitive to multiannual fluctuations in temperature, suggesting that with rising mean temperatures, dengue dynamics may become increasingly asynchronous. These findings can help underpin predictions of disease patterns as global temperatures rise.
March 2022
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265 Reads
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25 Citations
Synchronous dynamics (fluctuations that occur in unison) are universal phenomena with widespread implications for ecological stability. Synchronous dynamics can amplify the destabilizing effect of environmental variability on ecosystem functions such as productivity, whereas the inverse, compensatory dynamics, can stabilize function. Here we combine simulation and empirical analyses to elucidate mechanisms that underlie patterns of synchronous versus compensatory dynamics. In both simulated and empirical communities, we show that synchronous and compensatory dynamics are not mutually exclusive but instead can vary by timescale. Our simulations identify multiple mechanisms that can generate timescale‐specific patterns, including different environmental drivers, diverse life histories, dispersal, and non‐stationary dynamics. We find that traditional metrics for quantifying synchronous dynamics are often biased toward long‐term drivers and may miss the importance of short‐term drivers. Our findings indicate key mechanisms to consider when assessing synchronous versus compensatory dynamics and our approach provides a pathway for disentangling these dynamics in natural systems.
March 2022
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316 Reads
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12 Citations
Ecology Letters
Spatial synchrony may be tail‐dependent, that is, stronger when populations are abundant than scarce, or vice‐versa. Here, ‘tail‐dependent’ follows from distributions having a lower tail consisting of relatively low values and an upper tail of relatively high values. We present a general theory of how the distribution and correlation structure of an environmental driver translates into tail‐dependent spatial synchrony through a non‐linear response, and examine empirical evidence for theoretical predictions in giant kelp along the California coastline. In sheltered areas, kelp declines synchronously (lower‐tail dependence) when waves are relatively intense, because waves below a certain height do little damage to kelp. Conversely, in exposed areas, kelp is synchronised primarily by periods of calmness that cause shared recovery (upper‐tail dependence). We find evidence for geographies of tail dependence in synchrony, which helps structure regional population resilience: areas where population declines are asynchronous may be more resilient to disturbance because remnant populations facilitate reestablishment.
... Macroinvertebrates of the upper beach typically include talitrid amphipods, isopods, flies, and beetles, which can be extremely abundant depending on the availability of macroalgal wrack (Dugan et al. 2003;Lastra et al. 2008;Schooler 2018). The use of upper beach macroinvertebrates by surf zone fish could vary among locations and over time, depending on variability in wrack inputs, beach characteristics, and management (Revell et al. 2011;Liebowitz et al. 2016;Schooler et al. 2019;Walter et al. 2024), and the accessibility of these mobile prey to fish (Dugan et al. 2013;Emery et al. 2022). Macroalgal carbon could also enter the surf zone food web through reefassociated grazers that feed on kelp or kelp detritus (e.g., the isopod, Idotea spp.) exploited by surf zone fish (Crawley and Hyndes 2007;Andrades et al. 2014; Baring et al. 2018). ...
January 2024
Proceedings of the National Academy of Sciences
... In masting plants, a major mechanism governing the annual allocation of resources to seed production involves nonlinear responses of seed production to weather variations, known as weather cues (Kelly et al., 2013;Pearse et al., 2016). Consequently, the regional synchronization of masting arises from the Moran effect, that is, spatially correlated fluctuations in environmental drivers of masting (Ascoli et al., 2017;Bogdziewicz, Hacket-Pain, Ascoli, & Szymkowiak, 2021;Koenig & Knops, 2013;LaMontagne et al., 2020;Reuman et al., 2023;Wion et al., 2020). The mechanisms underlying F I G U R E 1 A graphical representation of the hypothetical association of seed production and weather cue and its consequence for spatial synchrony of mast seeding. ...
August 2023
... Land use change alters deep soil water and carbon, which are jointly regulated by multivariate controls of soil properties, especially within thick loess deposits (Dai et al. 2024). Currently, wavelet analysis has been applied in many fields, such as hydrology, ecology, and earth science (Carey et al. 2013;Castorani et al. 2022). Based on the continuous wavelet transform, the results of bivariate (BWC) and multivariate wavelet coherence (MWC) could reveal the independent and combined effects of multiple variables at various scales. ...
June 2022
Ecology Letters
... water flow discharge (Lazzaro et al. 2017), water temperature (Arevalo et al. 2021), nutrient limitation (Bernthal et al. 2022), environmental heterogeneity or genetic predisposition (Alò et al. 2021), and social interactions (Berdahl, Westley, and Quinn 2017). It is infeasible to fully describe the fish migration mechanism due to a number of random biological phenomena that can affect both inter-and intra-migration events, as suggested in the reported data for diverse case studies (Amtstaetter et al. 2021;Colborne et al. 2022;Fennell et al. 2023;Kaeding and Mogen 2023;Smith et al. 2021;Swanson et al. 2021). A concise-but nonetheless sufficiently realistic-stochastic process model is therefore essential for the analysis of fish migration. ...
June 2022
... Seasonal climate cycles are a strong predictor of annual cycling for many arboviruses, including dengue ( 10 , 11 ), and climate has been implicated as a possible driver of multiannual dengue periodicity, as well. In Thailand, multiannual dengue cycles demonstrate coherence with El Niño phenomena ( 29 ), and epidemic years exhibit more synchronized dynamics across latitudes ( 29 ), as well as higher correlation with local temperature than do interepidemic periods ( 28 ). The inter action of demography and heterotypic immunity is also thought to play a role in driving multiannual dengue cycles ( 24 , 26 , 30 ), which, in Thailand, show elongated periodicity as a result of declining birth rates and slower build-up of the susceptible pop ulation over the past half-century ( 24 ). ...
March 2022
... Here, we examine this hypothesis. We focused our investigation on giant kelp Macrocystis pyrifera, a broadly distributed marine foundation species that has served as an effective system for studies of synchrony in natural populations Cavanaugh et al., 2013;Reuman et al., 2023;Walter et al., 2022Walter et al., , 2024. Giant kelp is patchily distributed on rocky reefs in shallow coastal seas and demographically linked by ocean currents that disperse kelp spores (Castorani et al., 2015(Castorani et al., , 2017Reed et al., 2006). ...
March 2022
Ecology Letters
... Variation in species' responses to temporal changes in the environment can generate compensatory dynamics, allowing aggregate community properties (such as total biomass) to remain constant while the abundances of individual species fluctuate through time (Doak et al., 1998;Schindler et al., 2015). Finally, species with opposite responses to the same variables can coexist if their abundances increase and decrease with differences in the timing of favorable conditions (e.g., wet and dry seasons) (Gonzalez & Loreau, 2009;Shoemaker et al., 2022). Future work will disentangle the relative importance of these mechanisms in driving the patterns we documented here using manipulative experiments or modeling approaches. ...
March 2022
... Synchrony in life history patterns within and among species is a complex phenomenon shaped by ecological factors such as dispersal (Hopson and Fox 2019;Luo et al. 2021), density dependence (Loreau and de Mazancourt 2008), predator-prey relationships (Jarillo et al. 2020), competition (Jarillo et al. 2018) or exploitation (Morrongiello et al. 2021). For example, increased fisheries harvest can truncate demographic structure and increase populations' sensitivity to the environment, amplifying spatial synchrony among targeted stocks (Brander 2007;Morrongiello et al. 2021). ...
August 2021
Oikos
... Intense colors on the plot indicate strong synchrony at the given time and timescale. This method and a suite of closely related and now well developed methods have been applied numerous times to study synchrony of ecological time series 15,[49][50][51][52][53][54][55][56] , and the methods are implemented, open source, in the wsyn package on CRAN 48 . The wsyn package includes a "vignette" which gives a straightforward, operational introduction to the methods implemented therein. ...
December 2020
Ecology Letters
... The reason is as some extreme heatwave happens (shown by red dashed vertical line) the first three species (i = 1, 2, 3) cannot tolerate that high heat and would show extreme low abundance, whereas the last two species (i = 4, 5) would show extreme high abundances. On the contrary, we can expect a relatively higher value of tail-dependent synchrony during an extreme heat event if a community has species with similar tolerance limits or environmental thresholds [25][26][27] . For example, imagine the community shown in Fig. 1c now comprises the first three species only, i = 1, 2, 3. ...
November 2020