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

Dolecal, Renee E.; Long, Jeremy D.

doi:10.1890/13-2094.1

Cited by 16 publications

(10 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Research in kelp forests (Bray et al, , ; Hepburn & Hurd, ) and temperate tidepools (Bracken, Dolecal, & Long, ; Bracken & Nielsen, ) has shown that consumers enhance nutrient cycling and primary production. Bray et al () found that benthic macroinvertebrates and fishes collectively supplied 25–30 µmol NH 4 + m −2 hr −1 in kelp forests off Catalina Island, CA, similar to rates supplied by macroinvertebrates in our study system.…”

Section: Discussionmentioning

confidence: 99%

Climate and fishing drive regime shifts in consumer‐mediated nutrient cycling in kelp forests

Peters

Reed

Burkepile

2019

Global Change Biology

View full text Add to dashboard Cite

Globally, anthropogenic pressures are reducing the abundances of marine species and altering ecosystems through modification of trophic interactions. Yet, consumer declines also disrupt important bottom‐up processes, like nutrient recycling, which are critical for ecosystem functioning. Consumer‐mediated nutrient dynamics (CND) is now considered a major biogeochemical component of most ecosystems, but lacking long‐term studies, it is difficult to predict how CND will respond to accelerating disturbances in the wake of global change. To aid such predictions, we coupled empirical ammonium excretion rates with an 18‐year time series of the standing biomass of common benthic macroinvertebrates in southern California kelp forests. This time series of excretion rates encompassed an extended period of extreme ocean warming, disease outbreaks, and the abolishment of fishing at two of our study sites, allowing us to assess kelp forest CND across a wide range of environmental conditions. At their peak, reef invertebrates supplied an average of 18.3 ± 3.0 µmol NH4+ m−2 hr−1 to kelp forests when sea stars were regionally abundant, but dropped to 3.5 ± 1.0 µmol NH4+ m−2 hr−1 following their mass mortality due to disease during a prolonged period of extreme warming. However, a coincident increase in the abundance of the California spiny lobster, Palinurus interupptus (Randall, 1840), likely in response to both reduced fishing and a warmer ocean, compensated for much of the recycled ammonium lost to sea star mortality. Both lobsters and sea stars are widely recognized as key predators that can profoundly influence community structure in benthic marine systems. Our study is the first to demonstrate their importance in nutrient cycling, thus expanding their roles in the ecosystem. Climate change is increasing the frequency and severity of warming events, and rising human populations are intensifying fishing pressure in coastal ecosystems worldwide. Our study documents how these projected global changes can drive regime shifts in CND and fundamentally alter a critical ecosystem function.

show abstract

Section: Discussionmentioning

confidence: 99%

Climate and fishing drive regime shifts in consumer‐mediated nutrient cycling in kelp forests

Peters

Reed

Burkepile

2019

Global Change Biology

View full text Add to dashboard Cite

show abstract

“…In the Serengeti, for example, seasonal shortage of suitable food limits populations of large herbivores, while small herbivores are controlled primarily by carnivores (Sinclair et al 2010). Even in the rocky intertidal, an iconic example of top-down control of community structure and diversity (Paine 1966), the simultaneous importance of bottom-up processes is revealed by regional-scale comparisons among sites that differ in oceanographic parameters such as water column productivity and wave exposure (e.g., Menge 2000), as well as by mechanistic understanding of how context influences particular interactions (e.g., Bracken et al 2014). …”

mentioning

confidence: 99%

Bottom‐up and top‐down controls on coral reef sponges: disentangling within‐habitat and between‐habitat processes

Wulff

2017

Ecology

View full text Add to dashboard Cite

Polarized debates about top-down vs. bottom-up control have given way to more nuanced understanding of control by both resources and consumers in many systems, but coral reef sponges have recently been asserted to differ from other groups in being controlled exclusively top-down. This assertion has been countered by reports of exclusively bottom-up control, with both conclusions based on studies of the same species. Accelerating deterioration of coral reefs motivates knowing the contexts in which either consumers or nutrients or both control key ecosystem role players like sponges. Accordingly, genotype- and size-controlled individuals of 12 common Caribbean reef sponge species were transplanted, in the field, into five circumstances differing in predators, competitors, and the picoplankton consumed by sponges. Growth and survival of the experimental transplants for periods of 1-9 yr revealed context-dependent control of sponges. Primary control of growth was bottom-up, with more picoplankton resulting in consistent and sustained higher growth rates for all 12 of these ecologically and phylogenetically diverse species. Top-down control was not detected within-habitat, on the coral reef. However, between-habitat control was by predation and competition, with reef sponges excluded from adjacent seagrass meadows by spongivorous starfish, and excluded from mangrove prop roots by faster-growing mangrove sponges. These results highlight the strong importance of experimental design details that consider behavior idiosyncrasies, sufficiently long time scales, and appropriate division of species into categories. Diametrically opposite results from studies of the same species also illustrate the inherently greater difficulty of detecting bottom-up processes and the importance of distinguishing within-habitat vs. between-habitat patterns and processes.

show abstract

“…Plants may also directly benefit from throughfall nutrient inputs (especially when not having to compensate for severe herbivory‐induced biomass losses) as suggested for instance in a recent publication on potential facilitative effects among differently palatable seaweed species (Bracken et al ). We therefore analysed biomass log response ratios of plant communities finding that all communities responded negatively to herbivory, none fully compensating for biomass losses.…”

Section: Discussionmentioning

confidence: 99%

Increase of fast nutrient cycling in grassland microcosms through insect herbivory depends on plant functional composition and species diversity

Nitschke

Wiesner

Hilke

et al. 2014

Oikos

View full text Add to dashboard Cite

Nutrient cycling in terrestrial ecosystems is aff ected by various factors such as plant diversity and insect herbivory. While several studies suggest insect herbivory to depend on plant diversity, their interacting eff ect on nutrient cycling is unclear. In a greenhouse experiment with grassland microcosms of one to six plant species of two functional groups (grasses and legumes), we tested the infl uence of plant species richness (diversity) and functional composition on plant community biomass production, insect foliar herbivory, soil microbial biomass, and nutrient concentrations in throughfall. To manipulate herbivory, zero, three or six generalist grasshoppers ( Chorthippus parallelus ) were added to the plant communities. Increasing plant species richness increased shoot biomass and grasshopper performance, without signifi cantly aff ecting root biomass or insect herbivory. Plant functional composition aff ected all of these parameters, e.g. legume communities showed the highest shoot biomass, the lowest grasshopper performance and suff ered the least herbivory. Nutrient concentrations (dissolved mineral N, PO 4 -P, SO 4 -S) and pH in throughfall increased with herbivory. PO 4 -P and pH increases were positively aff ected by plant diversity, especially under high herbivore pressure. Plant functional composition aff ected several throughfall variables, sometimes fully explaining diversity eff ects. Increasing plant diversity tended to increase soil microbial biomass, but only under high herbivore pressure. Faeces quantities strongly correlated with changes in pH and PO 4 -P; frass may therefore be an important driver of throughfall pH and a main source of PO 4 -P released from living plants. Our results indicate that insect herbivory may signifi cantly infl uence fast nutrient cycling processes in natural communities, particularly so in managed grassland

show abstract

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

Cited by 16 publications

References 35 publications

Climate and fishing drive regime shifts in consumer‐mediated nutrient cycling in kelp forests

Climate and fishing drive regime shifts in consumer‐mediated nutrient cycling in kelp forests

Bottom‐up and top‐down controls on coral reef sponges: disentangling within‐habitat and between‐habitat processes

Increase of fast nutrient cycling in grassland microcosms through insect herbivory depends on plant functional composition and species diversity

Contact Info

Product

Resources

About