Spatial Ecology of Predator–prey Interactions: Corridors and Patch Shape Influence Seed Predation

Orrock, John L.; Danielson, Brent J.; Burns, Molly J.; Levey, Douglas J.

doi:10.1890/02-0439

Cited by 85 publications

(83 citation statements)

References 64 publications

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“…These results also indicate that the spatial and temporal scales of hypoxic episodes determine trophic effects (Diaz & Rosenberg 1995, Eby & Crowder 2004, as observed in other consumer-prey interactions (Orrock et al 2003). Our hypoxic sites were in close proximity (100s of meters) to shallow normoxic sites, where predators congregate during hypoxia (Lenihan et al 2001.…”

Section: Discussionsupporting

confidence: 77%

“…Such species probably do not exhibit increased vulnerability during hypoxia, because behavioral changes during hypoxic conditions should not affect their primary defense (Vermeij 1987). In contrast, species such as Macoma balthica and Mya arenaria (Taylor & Eggleston 2000), which have evolved a deep burial depth in response to predators, are more likely to be more vulnerable to predators under hypoxia because they migrate to the sediment surface where they are easily detected.These results also indicate that the spatial and temporal scales of hypoxic episodes determine trophic effects (Diaz & Rosenberg 1995, Eby & Crowder 2004, as observed in other consumer-prey interactions (Orrock et al 2003). Our hypoxic sites were in close proximity (100s of meters) to shallow normoxic sites, where predators congregate during hypoxia (Lenihan et al 2001.…”

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confidence: 77%

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Trophic interactions under stress: hypoxia enhances foraging in an estuarine food web

Long¹,

Seitz²

2008

Mar. Ecol. Prog. Ser.

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Ecosystem-level effects of stressors are critical to understanding community regulation, and environmental stress models are useful in describing such effects. Hypoxia is an important stressor in aquatic ecosystems that usually decreases abundance and biomass of benthic fauna. In field surveys, predator abundance is low in hypoxic areas, and in lab experiments, predators reduce their feeding rates under hypoxic conditions, leading to the hypothesis that consumer stress models (CSMs), rather than prey stress models (PSMs), apply to the systems. We tested predictions from these models with manipulative field experiments wherein we varied predator access to marked Macoma balthica clams at deep and shallow sites in the York River, Chesapeake Bay, before (June) and during (August) hypoxic episodes. In June, dissolved oxygen in deep and shallow sites was normoxic (> 2 mg l -1 ) for most of the experiment. In August, the shallow zone remained normoxic, while the deep zone experienced several hypoxic episodes. During hypoxia, predation rates in hypoxic sites were more than twice those in normoxic sites, whereas mortality due to physical stress did not differ between time periods or depths. Ambient clam densities were lower at the deep sites than at the shallow sites, and in August than in June. We conclude that hypoxia increased the susceptibility of benthic prey to predation, enhancing infaunal secondary production available to predators, but concurrently reducing the resilience of the benthic community. These findings are inconsistent with the predictions of CSMs, indicating that PSMs better describe this system. KEY WORDS: Environmental stress models · Food web · Hypoxia · Predation · Predator-prey · Macoma balthica Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 362: [59][60][61][62][63][64][65][66][67][68] 2008 long-lived species to small, opportunistic species. The magnitude of these effects generally increases with the severity of hypoxic stress.Hypoxia has a multitude of non-lethal effects. Metabolism, and thus oxygen demand, decreases (Wu 2002), reducing growth and reproductive output (e.g. Grove & Breitburg 2005, Long 2007. Infaunal organisms migrate vertically in the sediment, stretching their siphons or palps above the benthic boundary layer into higher DO concentrations, and they may expose themselves on the surface or float in the water column (Brafield 1963, Rosenberg et al. 1991, Taylor & Eggleston 2000, Seitz et al. 2003. Almost all species decrease oxygen demand by decreasing activity and feeding rates (Sagasti et al. 2001).These effects, especially the behavioral responses, potentially increase the availability of benthic fauna to their predators. The closer proximity of infaunal prey to the sediment surface and extension of siphons and palps decrease predator searching time. However, the responses of predators to hypoxia may jeopardize their ability to take advantage of stressed prey. Many predators in these systems are highly mobile, and ...

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Section: Discussionsupporting

confidence: 77%

supporting

confidence: 77%

Trophic interactions under stress: hypoxia enhances foraging in an estuarine food web

Long¹,

Seitz²

2008

Mar. Ecol. Prog. Ser.

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“…Once species colonize, we know from prior studies that corridors affect species interactions such as pollination (29) and seed predation (30), which may help to maintain elevated diversity in connected patches. Colonization sets an upper limit on the size of the local species pool, but it remains to be determined how much dispersal, relative to other factors, contributes to the long-term maintenance of elevated species richness.…”

Section: Resultsmentioning

confidence: 99%

How fragmentation and corridors affect wind dynamics and seed dispersal in open habitats

Damschen

Baker

Bohrer

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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140

124

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Determining how widespread human-induced changes such as habitat loss, landscape fragmentation, and climate instability affect populations, communities, and ecosystems is one of the most pressing environmental challenges. Critical to this challenge is understanding how these changes are affecting the movement abilities and dispersal trajectories of organisms and what role conservation planning can play in promoting movement among remaining fragments of suitable habitat. Whereas evidence is mounting for how conservation strategies such as corridors impact animal movement, virtually nothing is known for species dispersed by wind, which are often mistakenly assumed to not be limited by dispersal. Here, we combine mechanistic dispersal models, wind measurements, and seed releases in a large-scale experimental landscape to show that habitat corridors affect wind dynamics and seed dispersal by redirecting and bellowing airflow and by increasing the likelihood of seed uplift. Wind direction interacts with landscape orientation to determine when corridors provide connectivity. Our results predict positive impacts of connectivity and patch shape on species richness of wind-dispersed plants, which we empirically illustrate using 12 y of data from our experimental landscapes. We conclude that habitat fragmentation and corridors strongly impact the movement of wind-dispersed species, which has community-level consequences.H abitat loss and fragmentation sever movement pathways, posing major risks to population persistence and community diversity (1). As a result, landscape connectivity--the degree to which landscapes facilitate movement--is receiving growing attention as a means to increase long-distance dispersal (LDD) of individuals and persistence of species under global change (2, 3). In particular, habitat corridors, or linear strips of habitat connecting otherwise isolated habitat patches, have become one of the most commonly applied conservation tools (4, 5). However, corridors (and connectivity more generally) are almost exclusively considered a conservation strategy for animals or animaldispersed organisms, not for the great diversity of species that are passively transported by wind.Wind is a frequent means of movement for many organisms, including plant seeds, pollen, spores, insects, and pathogens (6-8). The changes in habitat structure (e.g., edge creation) that accompany habitat fragmentation and connectivity may strongly influence the flow of air, particularly the amount of vertical uplifting--a critical factor known to drive LDD of seeds by wind (9-11). Over the past decade, our mechanistic understanding of wind-driven seed dispersal has substantially increased (12, 13) and models have begun to incorporate landscape heterogeneity (11,(14)(15)(16)(17)(18). Combining mechanistic insight from dispersal models with dispersal patterns from real landscapes is the next frontier in understanding dispersal in fragmented habitats (12, 19-21).Gaining a mechanistic understanding of how habitat fragmentation and connecti...

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“…Seed predation by insects may change the recruitment rate and the abundance of the host plant (e.g., Jules, 1998;Louda, 1982). Several studies have investigated seed predation in fragmented landscapes and have shown that it may increase with fragmentation (Orrock, Danielson, & Burns, 2003;Fleury, & Galetti, 2006;Galetti, Donatti, & Pires, 2006;Orrock, Levey, & Danielson, 2006). Similarly to plant-pollinator interactions, other studies showed the opposite pattern, where antagonistic interactions may also be disturbed by fragmentation; possibly because the abundance and diversity of antagonistic animals in small populations of plants offer fewer resources to herbivores and seed predators (Colling, & Matthies, 2004;Kéry, Matthies, & Fischer, 2001;Ehlers, & Olesen, 2003).…”

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confidence: 99%

Reproductive success of Cabralea canjerana (Meliaceae) in Atlantic forest fragments, Brazil

Franceschinelli

Carmo

Neto

et al. 2015

RBT

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Abstract:In Brazil, the Atlantic forest remnants have high biological diversity and a high level of endemism, but very little is known about the reproductive success of native species. Cabralea canjerana is a common tree in the Montane Atlantic forest, and its reproduction is highly dependent on pollinators. In order to contribute with the particular knowledge on this species, we collected data in three fragmented and three continuous forest sites, where the effects of fragmentation on both mutualistic (pollination) and antagonistic (seed predation) interactions were analysed. We determined fruit production and weight of 25 trees per site. The number of seeds and the percentage of predated and aborted seeds were also accessed for seven fruits of 10 trees per site. Pollinator visitation frequencies to flowers were recorded in two forest fragments and in two sites of the continuous forest. Our data showed that plants of C. canjerana produced more fruits (z-value=-8.24; p<0.0001) and seeds per fruit (z-value=-6.58; p=0.002) in the continuous than in the fragmented sites. This was likely due to differences in pollination, because the number of pollinator visits was higher in the continuous forest than in the fragments. Seed abortion (z-value=4.08, p<0.001) and predation (z-value=3.72, p=0.0002), on the other hand, were higher in the fragmented than in the continuous sites. Then, mutualistic and antagonistic interactions were affected by fragmentation, decreasing the reproductive success of the study tree. This study was the first to show a decrease in the reproductive output in forest fragments in an Atlantic forest tree species. This decrease may threaten the population structure and viability of C. canjerana in forest fragments. Rev. Biol. Trop. 63 (2): 515-524. Epub 2015 June 01.Key words: Cabralea canjerana, fruit production, habitat fragmentation, plant-pollinator interaction, moth pollination, reproductive success, pre-dispersal seed predation, seed set.Habitat fragmentation may disrupt plantpollinator interactions by changing the abundance and/or the identity of floral visitors (Lovejoy, 1980;Roubik, 1993;Aizen, & Feinsinger, 1994a;Aizen, & Feinsinger, 1994b;Matheson, Buchamann, O'Toole, Westrich, & Williams, 1996;Murcia, 1996;Prach, Pysek, & Smilauer, 1997). Because floral visitors can differ in their ability to transfer pollen, changes in the pollinator assemblages following fragmentation may affect plant reproductive success (Aizen, & Feinsinger, 1994b). Studies conducted during the past few decades show that fragmentation may affect the reproduction of various plant species in different ways. Most of these studies show decreases in the richness and abundance of pollinators and in the number of pollinator visits in response to fragmentation, leading to a decrease in the reproductive output of plants (Aizen, & Feinsinger, 1994a;Kolb, 2008). In contrast, other studies found no changes in the reproductive output of plants in fragmented habitats (e.g., Aldrich & Hamrick, 1998;Dick, 2001;Lopes, & Buzato, 2007;...

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Spatial Ecology of Predator–prey Interactions: Corridors and Patch Shape Influence Seed Predation

Cited by 85 publications

References 64 publications

Trophic interactions under stress: hypoxia enhances foraging in an estuarine food web

Trophic interactions under stress: hypoxia enhances foraging in an estuarine food web

How fragmentation and corridors affect wind dynamics and seed dispersal in open habitats

Reproductive success of Cabralea canjerana (Meliaceae) in Atlantic forest fragments, Brazil

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