Species Coexistence, Keystone Species, and Succession: A Sensitivity Analysis

Tanner, Jason E.; Hughes, Terry P.; Connell, Joseph H.

doi:10.2307/1940877

Cited by 168 publications

(227 citation statements)

References 45 publications

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“…Studies of succession in coral communities following disturbance indicate that reshuffling of relative species abundances would continue without further increase in coral cover, given a more extensive recovery period (Tanner et al 1994;Hughes and Connell 1999). Species turnover and architectural development in coral communities may change over longer disturbance intervals.…”

Section: Favia Symphyllia Goniastreamentioning

confidence: 99%

Contrasting rates of coral recovery and reassembly in coral communities on the Great Barrier Reef

2014

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Changes in the relative abundances of coral taxa during recovery from disturbance may cause shifts in essential ecological processes on coral reefs. Coral cover can return to pre-disturbance levels (coral recovery) without the assemblage returning to its previous composition (i.e., without reassembly). The processes underlying such changes are not well understood due to a scarcity of longterm studies with sufficient taxonomic resolution. We assessed the trajectories and time frames for coral recovery and reassembly of coral communities following disturbances, using modeled trajectories based on data from a broad spatial and temporal monitoring program. We studied coral communities at six reefs that suffered substantial coral loss and subsequently regained at least 50 % of their pre-disturbance coral cover. Five of the six communities regained their coral cover and the rates were remarkably consistent, taking 7-10 years. Four of the six communities reassembled to their pre-disturbance composition in 8-13 years. The coral communities at three of the reefs both regained coral cover and reassembled ten years. The trajectories of two communities suggested that they were unlikely to reassemble and the remaining community did not regain pre-disturbance coral cover. The communities that regained coral cover and reassembled had high relative abundance of tabulate Acropora spp. Coral communities of this composition appear likely to persist in a regime of pulse disturbances at intervals of ten years or more. Communities that failed to either regain coral cover or reassemble were in near-shore locations and had high relative abundance of Porites spp. and soft corals. Under current disturbance regimes, these communities are unlikely to re-establish their pre-disturbance community composition.

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Section: Favia Symphyllia Goniastreamentioning

confidence: 99%

Contrasting rates of coral recovery and reassembly in coral communities on the Great Barrier Reef

2014

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“…However, cover continued to increase slowly, reaching only 35-40% after 12 yr. In the case of reef crests on Heron Island, a modeling study estimated that it would take 15-20 yr to reach an equilibrium species composition (Tanner et al 1994). The tempo of successional changes is likely to be slower on deeper reefs where rates of disturbance, recruitment, and growth tend to be slower.…”

Section: Natural Stressors and Regenerationmentioning

confidence: 99%

“…However, there is little evidence to support an equilibrium view of coral reefs and much to refute it (e.g., Connell 1978;Pearson 1981;Colgan 1987;Tanner et al 1994). Rates of mortality of reef-dwelling organisms are often very high, even in the absence of any major perturbations (e.g., Connell 1973;Stimson 1985;Bythell et al 1993).…”

mentioning

confidence: 99%

Multiple stressors on coral reefs: A long ‐term perspective

Hughes

Connell

1999

Limnology & Oceanography

556

376

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Coral reefs are subject to a high frequency of recurrent biological and physical disturbances. The temporal and spatial scales of these are often large and difficult to study, so that most of our knowledge of disturbances on coral reefs comes from investigations conducted at one or a few sites, over short periods of time. We argue that studying single events in isolation can be misleading and that a longer term approach is necessary for understanding the responses of coral reef assemblages to multiple stressors. We present first a brief review of the impacts of physical disturbance (e.g., cyclones, hurricanes) on the community dynamics of coral reefs, with special attention to the effects of recurrent events. We then examine two unusually detailed, long-term data sets from Heron Island, Australia, and Jamaica which demonstrate some of the complexities of multiple stressors (broadly defined as natural or man-made disturbances).Both case studies illustrate that the effect of a particular disturbance often depends critically on the impact of previous perturbations. Consequently, even the same type of recurrent stressor can have different effects at different times, depending on history. Accordingly, when the added dimension of time is considered, the distinction between single and multiple stressors becomes blurred. Even a single event such as a hurricane can be viewed mechanistically as a multiple stressor, with short-and long-term impacts. We emphasize that multiple stressors often have significant effects on recruitment and regenerative processes of assemblages. These impacts are much less obvious than catastrophic or chronic mortality, but they play a crucial role in community dynamics over longer time scales. Importantly, chronic anthropogenic impacts can impede the ability of coral assemblages to recover from natural disasters, even where there is little detectable effect on rates of adult mortality. Once a reef has been degraded, it is usually impossible to ascertain retrospectively the precise mechanisms that were involved or the relative importance of different events. A single survey will provide a snapshot of the status of coral reefs, but a longer term approach is required to understand the processes underlying changes in assemblages.Stress is often considered in the coral reef literature as a sublethal effect on the physiology of an animal or plant, e.g., a decline in feeding, growth, or fecundity, or a biochemical change. The term has also been used at the population or demographic level, usually in terms of an acute or chronic disturbance that causes a decline in the number of organisms. Increasingly, scientists, reef managers, and the general public also refer to stressed or degraded assemblages of species or ecosystems affected by natural and anthropogenic impacts, and there is growing concern about the health of coral reefs (e.g., see Brown and Howard 1985;Ginsberg 1993;Richmond 1993).The concerns for the declining status of many coral reefs are legitimate, although we caution that some of...

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“…Note that species replacement can happen directly through competitive displacement, or indirectly if the first plant dies and a second plant colonizes the same space (Tanner et al 1994). Recurrence times are also informative about our system.…”

Section: (C) Model Analysismentioning

confidence: 99%

Treatment-based Markov chain models clarify mechanisms of invasion in an invaded grassland community

Nelis

Wootton

2009

Proc. R. Soc. B.

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What are the relative roles of mechanisms underlying plant responses in grassland communities invaded by both plants and mammals? What type of community can we expect in the future given current or novel conditions? We address these questions by comparing Markov chain community models among treatments from a field experiment on invasive species on Robinson Crusoe Island, Chile. Because of seed dispersal, grazing and disturbance, we predicted that the exotic European rabbit (Oryctolagus cuniculus) facilitates epizoochorous exotic plants (plants with seeds that stick to the skin an animal) at the expense of native plants. To test our hypothesis, we crossed rabbit exclosure treatments with disturbance treatments, and sampled the plant community in permanent plots over 3 years. We then estimated Markov chain model transition probabilities and found significant differences among treatments. As hypothesized, this modelling revealed that exotic plants survive better in disturbed areas, while natives prefer no rabbits or disturbance. Surprisingly, rabbits negatively affect epizoochorous plants. Markov chain dynamics indicate that an overall replacement of native plants by exotic plants is underway. Using a treatment-based approach to multi-species Markov chain models allowed us to examine the changes in the importance of mechanisms in response to experimental impacts on communities.

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Species Coexistence, Keystone Species, and Succession: A Sensitivity Analysis

Cited by 168 publications

References 45 publications

Contrasting rates of coral recovery and reassembly in coral communities on the Great Barrier Reef

Contrasting rates of coral recovery and reassembly in coral communities on the Great Barrier Reef

Multiple stressors on coral reefs: A long ‐term perspective

Treatment-based Markov chain models clarify mechanisms of invasion in an invaded grassland community

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