Latitudinal variation in top-down and bottom-up control of a salt marsh food web

Marczak, Laurie B.; Ho, Chuan‐Kai; Więski, Kazimierz; Vu, Huy D.; Denno, Robert F.; Pennings, Steven C.

doi:10.1890/10-0760.1

Cited by 35 publications

(40 citation statements)

References 23 publications

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“…Marine ecologists have provided particularly good characterizations of food webs with studies of, for example, temperate rocky-shore intertidal communities (Paine 1969, Lubchenco 1978, Sousa 1979 and tropical benthic macroalgal communities (Hay 1981, Lewis 1985. Due to the complexity of most ecosystems, however, not only is some combination of top-down and bottom-up processes likely to be important (Hunter & Price 1992, Menge 2000, Ainley & Hyrenbach 2010, Denyer et al 2010), but also the relative importance of these processes may change along with other factors, such as latitude (Marczak et al 2011) or time (Whalen et al 2013).…”

Section: Introductionmentioning

confidence: 99%

A review of evidence for food limitation of sponges on Caribbean reefs

Pawlik¹,

McMurray²,

Erwin³

et al. 2015

Mar. Ecol. Prog. Ser.

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The diversity and biomass of sponges on Caribbean reefs exceeds that of all other benthic organisms. Wilkinson & Cheshire (1990; Mar Ecol Prog Ser 67:285−294) summarized evidence that sponge communities on Caribbean reefs were different from those on the Great Barrier Reef, Australia, reflecting food limitation of the latter, but not of the former. Since then, we have learned much about the ecology of sponges, and the concept of food limitation has recently reemerged, seemingly without substantive reference to past inter-oceanic comparisons or pioneering studies of sponge physiology. Here, we review the literature in an attempt to correct this digression. Based on current knowledge of sponge nutrition and bottom-up resource gradients (particulate food, dissolved organic carbon [DOC], light, turbulence), we predict 4 patterns of sponge abundance that would suggest food limitation on Caribbean reefs. After a critical review of survey data, correlative studies and manipulative experiments, we can find no evidence for food limitation. Although there is good evidence for higher availability of picoplankton at greater depths, sponge abundance does not mirror this gradient, suggesting that other sources of nutrition are also important, and particulate food is not a limiting factor. Recent studies have renewed interest in the uptake of DOC by both high and low microbial abundance sponge species, suggesting that the absence of bottom-up effects for sponges on Caribbean reefs may be attributable to this mysterious, and likely ubiquitous, food source. The recent unambiguous demonstration of topdown effects of predation on sponge community composition across the Caribbean may owe its clarity to the relative lack of confounding influences of abiotic and bottom-up effects in this study system.

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Section: Introductionmentioning

confidence: 99%

A review of evidence for food limitation of sponges on Caribbean reefs

Pawlik¹,

McMurray²,

Erwin³

et al. 2015

Mar. Ecol. Prog. Ser.

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“…Marsh elder ( Iva frutescens, hereafter Iva ) is a shrub found at the terrestrial border of the high marsh. Insect food web modules on Iva have been the focus of a number of previous studies of predator–prey interactions (Hacker & Bertness, 1995; Ho & Pennings, 2008; Marczak et al., 2011). We studied a simple system consisting of the most common herbivore on Iva , the aphid Uroleucon ambrosiae (hereafter Uroleucon ) (Hacker & Bertness, 1995), and its major predator at our study site, the spotless ladybeetle Cycloneda sanguinea (hereafter Cycloneda , Figure 1).…”

Section: Methodsmentioning

confidence: 99%

“…We studied a simple system consisting of the most common herbivore on Iva , the aphid Uroleucon ambrosiae (hereafter Uroleucon ) (Hacker & Bertness, 1995), and its major predator at our study site, the spotless ladybeetle Cycloneda sanguinea (hereafter Cycloneda , Figure 1). Other predators of Uroleucon at this site include other ladybeetles such as Coccinella septempunctata , Harmonia axyridis, and Hippodamia convergens , and an omnivorous crab Armases cinereum (Ho & Pennings, 2008; Marczak et al., 2011; Pennings et al., 2009). …”

Section: Methodsmentioning

confidence: 99%

“…In May 2014, we placed 81 potted plants (88.9 ± 1.03 (SE) cm tall, with 141 ± 3.9 (SE) leaves) in a fractal‐designed spatial array (Figure 1). These potted plants were smaller than most plants studied in the field, but were comparable in size to ones used in previous mesocosm experiments studying Iva arthropod food webs (Ho & Pennings, 2008; Marczak et al., 2011). The plants were set up in a grassy field (31°24ʹ18ʺ N, 81°16ʹ32ʺ W), about 500 m away from the marsh so that omnivorous marsh crabs ( Armases cinereum ) would have little access to the plants (none were observed at the experimental site during the study).…”

Section: Methodsmentioning

confidence: 99%

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Predator–prey interactions in a ladybeetle–aphid system depend on spatial scale

Lin

Pennings

2018

Ecology and Evolution

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The outcome of species interactions may manifest differently at different spatial scales; therefore, our interpretation of observed interactions will depend on the scale at which observations are made. For example, in ladybeetle–aphid systems, the results from small‐scale cage experiments usually cannot be extrapolated to landscape‐scale field observations. To understand how ladybeetle–aphid interactions change across spatial scales, we evaluated predator–prey interactions in an experimental system. The experimental habitat consisted of 81 potted plants and was manipulated to facilitate analysis across four spatial scales. We also simulated a spatially explicit metacommunity model parallel to the experiment. In the experiment, we found that the negative effect of ladybeetles on aphids decreased with increasing spatial scales. This pattern can be explained by ladybeetles strongly suppressing aphids at small scales, but not colonizing distant patches fast enough to suppress aphids at larger scales. In the experiment, the positive effects of aphids on ladybeetles were strongest at three‐plant scale. In a model scenario where predators did not have demographic dynamics, we found, consistent with the experiment, that both the effects of ladybeetles on aphids and the effects of aphids on ladybeetles decreased with increasing spatial scales. These patterns suggest that dispersal was the primary cause of ladybeetle population dynamics in our experiment: aphids increased ladybeetle numbers at smaller scales because ladybeetles stayed in a patch longer and performed area‐restricted searches after encountering aphids; these behaviors did not affect ladybeetle numbers at larger spatial scales. The parallel experimental and model results illustrate how predator–prey interactions can change across spatial scales, suggesting that our interpretation of observed predator–prey dynamics would differ if observations were made at different scales. This study demonstrates how studying ecological interactions at a range of scales can help link the results of small‐scale ecological experiments to landscape‐scale ecological problems.

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“…Most of this work has focused on local and regional scales, with few studies at large geographic (= continental) scales that span large gradients in climate, oceanographic drivers or soil type (but see Blanchette et al 2008;Marczak et al 2011;McCall & Pennings 2012). As a result, we currently have a poor understanding of the extent to which factors mediating variation in community structure at local scales also matter at geographic scales.…”

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confidence: 99%

Importance of local vs. geographic variation in salt marsh plant quality for arthropod herbivore communities

et al. 2013

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Summary1. An important recent advance in food web ecology has been the application of theory regarding spatial gradients to studies of the factors that affect animal population dynamics. Building on extensive studies of the Spartina alterniflora food web at the local scale, we hypothesized that geographic variation in S. alterniflora quality is an important bottom-up control on food web structure and that geographic variation in S. alterniflora quality would interact with the presence of predators and top omnivores to mediate herbivore densities. 2. We employed a four-factor fully crossed experiment in which we (i) collected plants from highand low-latitude locations and grew them in a common garden and varied (ii) plant fertilization status (mimicking the plant quality differences due to marsh elevation), (iii) mesopredator density and (iv) omnivore density. 3. Our results suggest that the single most important factor mediating insect herbivore densities is local variation in plant quality -induced in our experiment by fertilization and demonstrated repeatedly as a consequence of marsh elevation. 4. Top-down effects were generally weak and in those cases where predators did exert a significant suppressing effect on herbivores, that impact was itself mediated by host-plant characteristics. 5. Finally, despite observed variation in plant quality with latitude, and the separately measurable effects of this variation on herbivores, geographic-scale variation in plant quality was overwhelmed by local conditions in our experiments. 6. Synthesis. We suggest that a first-order understanding of variation across large latitudinal ranges in the Spartina alterniflora arthropod food web must begin with local variation in plant quality, which provides strong bottom-up forcing to herbivore populations. A second-order understanding of the arthropod food web should consider the role of predation in controlling herbivores feeding on lowquality plants. Finally, while latitudinal variation in plant quality probably explains some variation in herbivore densities, it is probably more of a response to herbivore pressure than a driver of the herbivore dynamics. Although extrapolating from local to geographic scales presents multiple challenges, it is an essential task in order for us to develop an understanding that is general rather than site-specific.

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Latitudinal variation in top-down and bottom-up control of a salt marsh food web

Cited by 35 publications

References 23 publications

A review of evidence for food limitation of sponges on Caribbean reefs

A review of evidence for food limitation of sponges on Caribbean reefs

Predator–prey interactions in a ladybeetle–aphid system depend on spatial scale

Importance of local vs. geographic variation in salt marsh plant quality for arthropod herbivore communities

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