Interactive Effects of Predator and Prey Harvest on Ecological Resilience of Rocky Reefs

Dunn, Robert P.; Baskett, Marissa L.; Hovel, Kevin A.

doi:10.1002/bes2.1343

Cited by 5 publications

(13 citation statements)

References 49 publications

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“…Specifically, smaller (e.g., younger or resource‐deprived) and more active sea urchin populations may be more susceptible to predation by spiny lobsters, which may alter the role that lobsters play in driving the dynamics of urchin prey. Recent studies have emphasized the importance of size‐structured interactions between lobsters and urchins in driving the dynamics of trophically linked species within the kelp forest (Dunn, Baskett, & Hovel, ). However, the role of intraspecific variation in urchin behavior in mediating these size‐structured interactions and the resulting effects on kelp forest ecosystem dynamics is not well‐studied.…”

Section: Discussionmentioning

confidence: 99%

Predator‐induced selection on urchin activity level depends on urchin body size

et al. 2019

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Temporally consistent individual differences in behavior impact many ecological processes. We simultaneously examined the effects of individual variation in prey activity level, covering behavior, and body size on prey survival with predators using an urchin–lobster system. Specifically, we tested the hypothesis that slow‐moving purple sea urchins (Strongylocentrotus purpuratus) and urchins who deploy extensive substrate (pebbles and stones) covering behavior will out‐survive active urchins that deploy little to no covering behavior when pitted against a predator, the California spiny lobster (Panulirus interruptus). We evaluated this hypothesis by first confirming whether individual urchins exhibit temporally consistent differences in activity level and covering behavior, which they did. Next, we placed groups of four urchins in mesocosms with single lobster and monitored urchin survival for 108 hr. High activity level was negatively associated with survival, whereas urchin size and covering behavior independently did not influence survival. The negative effect of urchin activity level on urchin survival was strong for smaller urchins and weaker for large urchins. Taken together, these results suggest that purple urchin activity level and size jointly determine their susceptibility to predation by lobsters. This is potentially of great interest, because predation by recovering lobster populations could alter the stability of kelp forests by culling specific phenotypes, like foraging phenotypes, from urchin populations.

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Section: Discussionmentioning

confidence: 99%

Predator‐induced selection on urchin activity level depends on urchin body size

et al. 2019

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“…Alternative stable food web states can theoretically arise from strong feedback loops in many ecosystems, including pelagic food webs dominated by predators or prey (De Roos and Persson 2002; Persson et al 2007), Caribbean tropical reefs dominated by grazing fish and corals or macroalgae (Bellwood et al 2004; Mumby et al 2007; Bruno et al 2009), and salt marshes with abundant herbivores or dense vegetation (van de Koppel et al 1996). Most studies predicting the potential for alternative stable states, however, either consider 1-3 populations and omit all other taxa (De Roos and Persson 2002; Dunn et al 2017) or aggregate species into larger guilds (Scheffer 1998; Mumby et al 2007; May 2009). In reality, populations are embedded in larger food webs that can dissipate feedback loops across different species (Neutel et al 2002), or heterogeneity within guilds might lead to species-specific dynamics (Lever et al 2014).…”

Section: Introductionmentioning

confidence: 99%

“…In investigations into the effect of focal feedbacks, most models predicting the potential for alternative stable states either consider 1-3 populations and omit all other taxa (De Roos and Persson 2002; Dunn et al 2017) or aggregate species into larger guilds (Scheffer 1998; Mumby et al 2007; May 2009). In reality, populations are embedded in larger food webs that can dissipate feedback loops across different species (Neutel et al 2002), and heterogeneity within guilds might lead to species-specific dynamics (Lever et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Quantifying the relevance of alternative stable states in many-species food webs

Karatayev

Baskett

Nes

2020

Preprint

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Overexploitation can lead to a rapid collapse of consumers that is difficult to reverse if ecosystems exhibit alternative stable states. However, support for this phenomenon remains predominantly limited to simple models, whereas food webs might dissipate the feedback loops that create alternative stable states through species-specific demography and interactions. Here we develop a general model of consumer-resource interactions with two types of processes: either specialized feedbacks where individual resources become unpalatable at high abundance or aggregate feedbacks where overall resource abundance reduces consumer recruitment. We then quantify how the degree of interconnectedness and species differences in demography affect the potential for either feedback to produce consumer- or resource-dominated food web states. Our results highlight that such alternative stable states could be more likely to happen 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 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 fragility absent in few-species models. Altogether, we suggest that species heterogeneity has a greater impact on whether feedbacks prevent consumer recovery than on the presence of many-species collapses.

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“…Correlative and theoretical evidence suggest that when rocky‐reef‐associated predators are removed, kelp forests are susceptible to a shift into urchin barrens (Scheibling , Lafferty , Hamilton and Caselle , Dunn et al. ). However, physical forces also affect the distribution and persistence of habitat‐providing macroalgae in this region (reviewed in Schiel and Foster ), and the relative importance of top‐down control remains contentious (Foster et al.…”

Section: Introductionmentioning

confidence: 99%

Experiments reveal limited top‐down control of key herbivores in southern California kelp forests

Dunn

Hovel

2019

Ecology

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Predator responses to gradients in prey density have important implications for population regulation and are a potential structuring force for subtidal marine communities, particularly on rocky reefs where herbivorous sea urchins can drive community state shifts. On rocky reefs in southern California where predatory sea otters have been extirpated, top‐down control of sea urchins by alternative predators has been hypothesized but rarely tested experimentally. In laboratory feeding assays, predatory spiny lobsters (Panulirus interruptus) demonstrated a saturating functional response to urchin prey, whereby urchin proportional mortality was inversely density‐dependent. In field experiments on rocky reefs near San Diego, California, predators (primarily the labrid fish California sheephead, Semicossyphus pulcher) inflicted highly variable mortality on purple urchin (Strongylocentrotus purpuratus) prey across all density levels. However, at low to moderate densities commonly observed within kelp forests, purple urchin mortality increased to a peak at a density of ~11 urchins/m2. Above that level, at densities typical of urchin barrens, purple urchin mortality was density‐independent. When larger red urchins (Mesocentrotus franciscanus) were offered to predators simultaneously with purple urchins, mortality was density‐independent. Underwater videography revealed a positive relationship between purple urchin density and both the number and richness of fish predators, but these correlations were not observed when red urchins were present. Our results demonstrate highly variable mortality rates across prey densities in this system and suggest that top‐down control of urchins can occur only under limited circumstances. Our findings provide insight into the dynamics of alternate community states observed on rocky reefs.

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Interactive Effects of Predator and Prey Harvest on Ecological Resilience of Rocky Reefs

Cited by 5 publications

References 49 publications

Predator‐induced selection on urchin activity level depends on urchin body size

Predator‐induced selection on urchin activity level depends on urchin body size

Quantifying the relevance of alternative stable states in many-species food webs

Experiments reveal limited top‐down control of key herbivores in southern California kelp forests

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