Season-specific impacts of climate change on canopy-forming seaweed communities.

Understory assemblages associated with canopy-forming species such as trees, kelps, and rockweeds should respond strongly to climate stressors due to strong canopy-understory interactions. Climate change can directly and indirectly modify these assemblages, particularly during more stressful seasons and climate scenarios. However, fully understanding the seasonal impacts of different climate conditions on canopy-reliant assemblages is difficult due to a continued emphasis on studying single-species responses to a single future climate scenario during a single season.

Aboveground competition influences density-dependent effects of cordgrass on sediment biogeochemistry.

Interspecific interactions between plants influence plant phenotype, distribution, abundance, and community structure. Each of these can, in turn, impact sediment biogeochemistry. Although the population and community level impacts of these interactions have been extensively studied, less is known about their effect on sediment biogeochemistry.

Population responses of omnivorous arthropods to plant alternative resources suppress prey populations: A meta-analysis.

Omnivory is ubiquitous in ecological communities. Yet, we lack a consensus of how plant alternative resources impact the ability of omnivores to suppress prey populations. Previous work suggests that plant alternative resources can increase, decrease, or have no effect on the magnitude of omnivore-prey interactions.

Local and regional variation in effects of burrowing crabs on plant community structure.

Burrowing animals can profoundly influence the structure of surrounding communities, as well as the performance of individual species. Changes in the community structure of burrowing animals or plants together with changing abiotic parameters could shift the influence of burrowers on surrounding habitats. For example, prior studies in salt marshes suggest that fiddler crabs stimulate cordgrass production, but leaf-grazing crabs suppress cordgrass production.

Geographic variation in the sensitivity of an herbivore-induced seaweed defense.

Intraspecific variation in primary producer induced defenses may affect how these defenses contribute to population and community regulation. For instance, inducible defenses may play larger roles in primary producer populations that are sensitive to low levels of grazing than populations that only respond to high levels of grazing. Although the incidence of herbivore-induced defenses is well documented, and there are examples of geographic variation in these defenses, we have limited knowledge of the factors that affect sensitivity to grazing (i.

Fish predators reduce kelp frond loss via a trait-mediated trophic cascade.

Although trophic cascades were originally believed to be driven only by predators eating prey, there is mounting evidence that such cascades can be generated in large part via non-consumptive effects. This is especially important in cascades affecting habitat-forming foundation species that in turn, influence associated communities. Here, we use laboratory and field experiments to identify a trait-mediated indirect interaction between predators and an abundant kelp in a marine temperate reef system.

Declines in plant palatability from polar to tropical latitudes depend on herbivore and plant identity.

Long-standing theory predicts that the intensity of consumer-prey interactions declines with increasing latitude, yet for plant-herbivore interactions, latitudinal changes in herbivory rates and plant palatability have received variable support. The topic is of growing interest given that lower-latitude species are moving poleward at an accelerating rate due to climate change, and predicting local interactions will depend partly on whether latitudinal gradients occur in these critical biotic interactions. Here, we assayed the palatability of 50 seaweeds collected from polar (Antarctica), temperate (northeastern Pacific; California), and tropical (central Pacific; Fiji) locations to two herbivores native to the tropical and subtropical Atlantic, the generalist crab Mithraculus sculptus and sea urchin Echinometra lucunter.

A tide prediction and tide height control system for laboratory mesocosms.

Experimental mesocosm studies of rocky shore and estuarine intertidal systems may benefit from the application of natural tide cycles to better replicate variation in immersion time, water depth, and attendant fluctuations in abiotic and edaphic conditions. Here we describe a stand-alone microcontroller tide prediction open-source software program, coupled with a mechanical tidal elevation control system, which allows continuous adjustment of aquarium water depths in synchrony with local tide cycles. We used this system to monitor the growth of Spartina foliosa marsh cordgrass and scale insect herbivores at three simulated shore elevations in laboratory mesocosms.

Copper Contamination Impairs Herbivore Initiation of Seaweed Inducible Defenses and Decreases Their Effectiveness.

Seaweed-herbivore interactions are often mediated by environmental conditions, yet the roles of emerging anthropogenic stressors on these interactions are poorly understood. For example, chemical contaminants have unknown consequences on seaweed inducible resistance and herbivore response to these defenses despite known deleterious effects of contaminants on animal inducible defenses. Here, we investigated the effect of copper contamination on the interactions between a snail herbivore and a brown seaweed that displays inducible resistance to grazing.

Herbivore impacts on marsh production depend upon a compensatory continuum mediated by salinity stress.

Plant communities are disturbed by several stressors and they are expected to be further impacted by increasing anthropogenic stress. The consequences of these stressors will depend, in part, upon the ability of plants to compensate for herbivory. Previous studies found that herbivore impacts on plants can vary from negative to positive because of environmental control of plant compensatory responses, a.

Community context mediates the top-down vs. bottom-up effects of grazers on rocky shores.

Interactions between grazers and autotrophs are complex, including both top-down consumptive and bottom-up facilitative effects of grazers. Thus, in addition to consuming autotrophs, herbivores can also enhance autotroph biomass by recycling limiting nutrients, thereby increasing nutrient availability. Here, we evaluated these consumptive and facilitative interactions between snails (Littorina littorea) and seaweeds (Fucus vesiculosus and Ulva lactuca) on a rocky shore.

Local consumers induce resistance differentially between Spartina populations in the field.

Intraspecific variation in the strength of inducible plant defenses plays a central role in the interactions between plants and herbivores. Studies of this variation are typically conducted in the greenhouse or laboratory rather than the field. We simultaneously manipulated densities of local consumers in the field within Maine and South Carolina populations of the smooth cordgrass Spartina alterniflora.

Linking invasions and biogeography: isolation differentially affects exotic and native plant diversity.

The role of native species diversity in providing biotic resistance to invasion remains controversial, with evidence supporting both negative and positive relationships that are often scale dependent. Across larger spatial scales, positive relationships suggest that exotic and native species respond similarly to factors other than diversity. In the case of island habitats, such factors may include island size and isolation from the mainland.

Chemical cues induce consumer-specific defenses in a bloom-forming marine phytoplankton.

Blooms of the phytoplankton Phaeocystis can comprise 85% of total production and generate major biogeochemical signals across broad oceanic regions. The success of Phaeocystis may result from its ability to change size by many orders of magnitude when it shifts from small cells of 4-6 microm to large colonies of up to 30,000 microm in diameter. Single cells are consumed by ciliates but not copepods, whereas colonies are consumed by copepods but not ciliates.

Asymmetric competition via induced resistance: specialist herbivores indirectly suppress generalist preference and populations.

Species may compete indirectly by altering the traits of a shared resource. For example, herbivore-induced responses in plants may make plants more resistant or susceptible to additional herbivorous insect species. Herbivore-induced plant responses can significantly affect interspecific competition and herbivore population dynamics.