Eastern oysters Crassostrea virginica deter crab predators by altering their morphology in response to crab cues

Robinson, Elizabeth; Lunt, Jessica; Marshall, Christopher D.; Smee, Delbert L.

doi:10.3354/ab00549

Cited by 52 publications

(64 citation statements)

References 53 publications

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“…; Johnson & Smee ; Lord & Whitlatch ; Robinson et al. ). However, the intensity of these responses is influenced by oyster size and by the type of predation cues available to oysters.…”

Section: Discussionmentioning

confidence: 99%

“…Measured masses contained both shell and soft tissue, but ~99% of the total mass is shell at this point in development (Robinson et al. ). The shell's compression force, or the amount of force required to crush the shell, was measured with a Kistler 5995 charge amplifier and Kistler 9203 force sensor ( sensu Robinson et al.…”

Section: Methodsmentioning

confidence: 99%

“…The shell's compression force, or the amount of force required to crush the shell, was measured with a Kistler 5995 charge amplifier and Kistler 9203 force sensor ( sensu Robinson et al. ). The settings for the charge amplifier were sensitivity 47.8 and range 50.…”

Section: Methodsmentioning

confidence: 99%

“…We recorded the maximum force needed to break the shell as our measurement of the hardness of the prey, which is an appropriate proxy for the shell's strength (Robinson et al. ).…”

Section: Methodsmentioning

confidence: 99%

“…; Johnson & Smee ; Lord & Whitlatch ; Robinson et al. ). Although little is known about the types of cues used by oysters to assess the risk of predation, other bivalve species utilize cues both from predators and from injured prey (Smee & Weissburg ), and can distinguish between predators fed different diets (Griffiths & Richardson ; Large & Smee ).…”

Section: Model Systemmentioning

confidence: 99%

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Phenotypic plasticity in oysters (Crassostrea virginica) mediated by chemical signals from predators and injured prey

Scherer

Lunt

Draper

et al. 2016

Invertebrate Biology

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Prey organisms reduce predation risk by altering their behavior, morphology, or life history. Avoiding or deterring predators often incurs costs, such as reductions in growth or fecundity. Prey minimize costs by limiting predator avoidance or deterrence to situations that pose significant risk of injury or death, requiring them to gather information regarding the relative threat potential predators pose. Chemical cues are often used for risk evaluation, and we investigated morphological responses of oysters (Crassostrea virginica) to chemical cues from injured conspecifics, from heterospecifics, and from predatory blue crabs (Callinectes sapidus) reared on different diets. Previous studies found newly settled oysters reacted to crab predators by growing heavier, stronger shells, but that adult oysters did not. We exposed oysters at two size classes (newly settled oyster spat and juveniles~2.0 cm) to predation risk cue treatments including predator or injured prey exudates and to seawater controls. Since both of the size classes tested can be eaten by blue crabs, we hypothesized that both would react to crab exudates by producing heavier, stronger shells. Oyster spat grew heavier shells that required significantly more force to break, an effective measure against predatory crabs, when exposed to chemical exudates from blue crabs as compared to controls. When exposed to chemical cues from injured conspecifics or from injured clams (Mercenaria mercenaria), a sympatric bivalve, shell mass and force were intermediate between predator treatments and controls, indicating that oysters react to injured prey cues but not as strongly as to cues released by predators. Juvenile oysters of~2.0 cm did not significantly alter their shell morphology in any of the treatments. Thus, newly settled oysters can differentiate between predatory threats and adjust their responses accordingly, with the strongest responses being to exudates released by predators, but oysters of 2.0 cm and larger do not react morphologically to predatory threats.

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“…; Johnson & Smee ; Lord & Whitlatch ; Robinson et al. ). However, the intensity of these responses is influenced by oyster size and by the type of predation cues available to oysters.…”

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…We recorded the maximum force needed to break the shell as our measurement of the hardness of the prey, which is an appropriate proxy for the shell's strength (Robinson et al. ).…”

Section: Methodsmentioning

confidence: 99%

Section: Model Systemmentioning

confidence: 99%

See 3 more Smart Citations

Phenotypic plasticity in oysters (Crassostrea virginica) mediated by chemical signals from predators and injured prey

Scherer

Lunt

Draper

et al. 2016

Invertebrate Biology

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Environmental gradients influence biogeographic patterns of nonconsumptive predator effects on oysters

et al. 2020

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When prey alter behavioral or morphological traits to reduce predation risk, they often incur fitness costs through reduced growth and reproduction as well as increased mortality that are known as nonconsumptive effects (NCEs). Environmental context and trophic structure can individually alter the strength of NCEs, yet the interactive influence of these contexts in natural settings is less understood. At six sites across 1000 km of the Southeastern Atlantic Bight (SAB), we constructed oyster reefs with one, two, or three trophic levels and evaluated the traits of focal juvenile oysters exposed to predation risk cues. We monitored environmental variables (water flow velocity, microalgal resources, and oyster larval recruitment) that may have altered how oysters respond to risk, and we also assessed the cost of trait changes to oyster mortality and growth when they were protected from direct predatory loss. Regardless of trophic structure, we found that oyster shell strength and natural oyster recruitment peaked at the center of the region. This high recruitment negated the potential for NCEs by smothering and killing the focal oysters. Also independent of trophic structure, focal oysters grew the most at the northernmost site. In contrast to, and perhaps because of, these strong environmental effects, the oyster traits of condition index and larval recruitment were only suppressed by the trophic treatment with a full complement of risk cues from intermediate and top predators at just the southernmost site. But at this same site, statistically significant NCEs on oyster growth and mortality were not detected. More strikingly, our study demonstrated environmental gradients that differentially influence oysters throughout the SAB. In particular, the results of our trophic manipulation experiment across these gradients suggest that in the absence of predation, environmental differences among sites may overwhelm the influence of NCEs on prey traits and population dynamics.

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Nonconsumptive effects of a predator weaken then rebound over time

Kimbro

Grabowski

Hughes

et al. 2017

Ecology

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Predators can influence prey traits and behavior (nonconsumptive effects [NCEs]), often with cascading effects for basal resources and ecosystem function. But critiques of NCE experiments suggest that their duration and design produce results that describe the potential importance of NCEs rather than their actual importance. In light of these critiques, we re-evaluated a toadfish (predator), crab (prey), and oyster (resource) NCE-mediated trophic cascade. In a 4-month field experiment, we varied toadfish cue (NCE) and crab density (approximating variation in predator consumptive effects, CE). Toadfish initially benefitted oyster survival by causing crabs to reduce consumption. But this NCE weakened over time (possibly due to prey hunger), so that after 2 months, crab density (CE) dictated oyster survivorship, regardless of cue. However, the NCE ultimately re-emerged on reefs with a toadfish cue, increasing oyster survivorship. At no point did the effect of toadfish cue on mud crab foraging behavior alter oyster population growth or sediment organic matter on the reef, which is a measure of benthic-pelagic coupling. Instead, both decreased with increasing crab density. Thus, within a system shown to exhibit strong NCEs in short-term experiments (days) our study supported predictions from theoretical models: (a) within the generation of individual prey, the relative influence of NCEs appears to cycle over longer time periods (months); and (b) predator CEs, not NCEs, drive longer-term resource dynamics and ecosystem function. Thus, our study implies that the impacts of removing top predators via activities such as hunting and overfishing will cascade to basal resources and ecosystem properties primarily through density-mediated interactions.

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Eastern oysters Crassostrea virginica deter crab predators by altering their morphology in response to crab cues

Cited by 52 publications

References 53 publications

Phenotypic plasticity in oysters (Crassostrea virginica) mediated by chemical signals from predators and injured prey

Phenotypic plasticity in oysters (Crassostrea virginica) mediated by chemical signals from predators and injured prey

Environmental gradients influence biogeographic patterns of nonconsumptive predator effects on oysters

Nonconsumptive effects of a predator weaken then rebound over time

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