Consumer mobility and the relative importance of consumption and competition following physical disturbance

Breitburg, DL

doi:10.3354/meps138083

Cited by 6 publications

(4 citation statements)

References 35 publications

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“…While the direct cause of this shift at Williamstown is unclear, such a result can occur if the threshold between grazing activity and algal primary productivity is overcome (Harrold and Reed , Breitberg ). If primary productivity is relatively constant, reducing grazing pressure is one way to do this (e.g.…”

Section: Discussionmentioning

confidence: 99%

The influence of herbivores on primary producers can vary spatially and interact with disturbance

Carnell

Keough

2016

Oikos

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Identifying the major drivers of ecosystem change remains a central area of ecological research. Although top-down drivers of change have received particular focus, we still have little understanding of how consistently these factors control an ecosystem's shift in both directions, between different ecosystem states. Using a crossed experiment in a shallow embayment in southeastern Australia, we investigated the roles of disturbance (kelp removal) and sea urchin herbivory (via increased density) to determine their contributions to shifts away from a kelp-dominated community. In a second experiment, done in urchin barren areas at two sites, we tested whether reductions in ambient sea urchin densities allowed an algal shift in the reverse direction. In both experiments, we observed that high densities of sea urchins could negatively influence kelp and macroalgal abundance. However, in the kelp bed, a moderate or severe disturbance resulted in a comparable algal response, irrespective of urchin density. The influence of sea urchins also varied dramatically between the two urchin barren sites. Here, reducing urchin densities resulted in algal recovery at one site, but at the other site, substantial colonisation of barren areas by canopy-forming brown algae and Ulvales occurred across all (low, medium, and high) urchin density treatments. Our findings illustrate multiple pathways of urchin barren creation and algal recovery, and reveal that shifts both to and from an urchin barren state can occur irrespective of herbivore pressure. These alternate pathways can operate over short spatial distances or with different regimes of disturbance.

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Section: Discussionmentioning

confidence: 99%

The influence of herbivores on primary producers can vary spatially and interact with disturbance

Carnell

Keough

2016

Oikos

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“…Monthly consumption C i , t (in kg) is related to kelp biomass in the cell in which agent i is found j ( i ) at time t , K j ( j ), t using a Holling type II functional response relationship (Holling ; Eq. ) based on the assumption that sea urchins are limited by its capacity to process food (Breitburg ):

C_{i, t} = W_{i, t} \cdot c_{normalmax} \cdot (\frac{K_{j (i), t}}{c_{50} + K_{j false(i false), t}})

where W is the wet weight of sea urchins (kg), c max is the maximum monthly consumption rate (kg·kg −1 ·month −1 ), and c 50 is the half‐saturation constant. Although sea urchin consumption was negatively correlated with sea water temperature in experimental conditions (from 10.1 to 16.8°C; McBride et al.…”

Section: Methodsmentioning

confidence: 99%

“…Monthly consumption C i,t (in kg) is related to kelp biomass in the cell in which agent i is found j (i) at time t, K j(j),t using a Holling type II functional response relationship (Holling 1959;Eq. 2) based on the assumption that sea urchins are limited by its capacity to process food (Breitburg 1996):…”

Section: Individual Growthmentioning

confidence: 99%

Exploring benefits of spatial cooperative harvesting in a sea urchin fishery: an agent‐based approach

et al. 2017

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Citation: Gutierrez, N. L., P. Halmay, R. Hilborn, A. E. Punt, and S. Schroeter. 2017. Exploring benefits of spatial cooperative harvesting in a sea urchin fishery: an agent-based approach. Ecosphere 8(7):e01829. 10.1002/ecs2.1829Abstract. Sedentary or low-mobility organisms show a high degree of dependency with their substrate, where its heterogeneity often determines small-scale spatial patterns of distribution, life history traits, and fishery yields. For sea urchins, this spatial structure is usually shaped by food availability, habitat structure, individual movement, and fishery dynamics. All of these have a significant impact on their physiological and reproductive status and in particular on their gonadal content. These patterns are of particular interest considering that the sea urchin fishery is a roe fishery where marketability depends on gonad yield and quality, which in turn is related to spatial and temporal variations in associated kelp beds. Thus, better gonad quality and yields generate higher profits for both fishers (divers) and processors. However, competition among divers within a non-cooperative system creates a "race for shellfish" precluding higher gonad yields per unit of effort. A spatially explicit agent-based model for the San Diego, California red sea urchin (Strongylocentrotus franciscanus) fishery was developed in order to assess the benefits of cooperative harvesting by depicting spatial and temporal variations in fishery yields. A cooperative harvesting scenario where divers consistently target those areas with higher yields avoiding low-quality sea urchins was compared against a non-cooperative situation where divers harvest at random or based only on densities of sea urchins. Sea urchin population at the end of the simulation period was 20% higher for the most cooperative scenario compared to the non-cooperative fishery. Further, for the most cooperative scenario where information sharing among divers is greatest and harvest is coordinated, sea urchin catches were at least 10% higher and gonad yield 35% higher than in the non-cooperative scenario. In this model, information sharing and organized harvesting typical of well-functioning cooperatives allowed fishers to optimize the use of the resource in terms of higher gonad yields per unit of effort while maintaining the productivity of the stock. This study also highlights the importance of community-based management (i.e., collaborative efforts in assessment, management, and governance of fisheries between fishers, scientists, and managers) toward improving fisheries sustainability.

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“…This suggests that temporal changes in infauna were not necessarily related to the magnitude of the tsunami disturbance. Various factors can simultaneously affect temporal changes in infaunal abundance and community structure, such as physical disturbance caused by monsoon storms, and sedimentation due to river discharge during rainy seasons, and changes in food availability and predation pressures (e.g., Virnstein, 1977;Breitburg, 1996;Frost et al,1999;Nakaoka et al, 2004). These causes have an influence on macrobenthic faunal community composition via modification of both the physical nature of habitats and biological interactions.…”

Section: Discussionmentioning

confidence: 99%

Tsunami Impacts on Biodiversity of Seagrass Communities in the Andaman Sea, Thailand: (2) Abundance and Diversity of Benthic Animals

Whanpetch¹,

Nakaoka²,

Mukai³

et al. 2007

Publ. SMBL. SPS

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Seagrass beds support highly productive and diverse animal communities. Extreme physical disturbances such as tsunamis are expected to affect the abundance and diversity of both the seagrass and the infaunal community. To examine the effects of a tsunami on infaunal seagrass communities, we compared the communities in seagrass beds before and after the tsunami that hit the Andaman Sea coast of Thailand on December 26th, 2004. Infauna were collected in 2001 and again in 2005 from inside and outside seagrass vegetation. Polychaetes were the most abundance taxa, followed by crustaceans. Density of macrobenthic animals varied greatly among sites, among areas inside and outside the vegetated areas and between the two years. The density increased over time in the areas with seagrass while it deceased in the non-vegetated areas, suggesting that the tsunami impacted the two areas differently. Multivariate analysis on the polychaete assemblage revealed that temporal changes in assemblage structure differed between vegetated and non-vegetated areas, and that the degree of temporal changes in assemblage structure was not necessarily related to the magnitude of the tsunami.

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Consumer mobility and the relative importance of consumption and competition following physical disturbance

Cited by 6 publications

References 35 publications

The influence of herbivores on primary producers can vary spatially and interact with disturbance

The influence of herbivores on primary producers can vary spatially and interact with disturbance

Exploring benefits of spatial cooperative harvesting in a sea urchin fishery: an agent‐based approach

Tsunami Impacts on Biodiversity of Seagrass Communities in the Andaman Sea, Thailand: (2) Abundance and Diversity of Benthic Animals

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