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Mechanisms underlying community shif...

Rassweiler, Andrew James.

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Mechanisms underlying community shifts in the Santa Barbara Channel.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Mechanisms underlying community shifts in the Santa Barbara Channel./
Author:	Rassweiler, Andrew James.
Description:	121 p.
Notes:	Source: Dissertation Abstracts International, Volume: 70-01, Section: B, page: 0058.
Contained By:	Dissertation Abstracts International70-01B.
Subject:	Biology, Ecology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3342040
ISBN:	9780549988007

Mechanisms underlying community shifts in the Santa Barbara Channel.
Rassweiler, Andrew James.

Mechanisms underlying community shifts in the Santa Barbara Channel. - 121 p.

Source: Dissertation Abstracts International, Volume: 70-01, Section: B, page: 0058.

Thesis (Ph.D.)--University of California, Santa Barbara, 2008.

Spatial patterns in the distribution of organisms and temporal changes in populations are often driven by environmental variation. However, dramatic shifts in community state may also occur with little change in the underlying environment. For example, adjacent sections of a similar landscape can support very different communities and communities can shift abruptly through time from one state to another with little or no accompanying environmental change. These patterns may represent threshold responses to the environment, or they may represent alternative stable states, in which positive feedbacks maintain different community states under the same environmental conditions.

ISBN: 9780549988007Subjects--Topical Terms:

1017726
Biology, Ecology.

Mechanisms underlying community shifts in the Santa Barbara Channel.
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020 $a 9780549988007
035 $a (UMI)AAI3342040
035 $a AAI3342040
040 $a UMI $c UMI
100 1 $a Rassweiler, Andrew James. $3 1683730
245 1 0 $a Mechanisms underlying community shifts in the Santa Barbara Channel.
300 $a 121 p.
500 $a Source: Dissertation Abstracts International, Volume: 70-01, Section: B, page: 0058.
500 $a Adviser: Sally J. Holbrook.
502 $a Thesis (Ph.D.)--University of California, Santa Barbara, 2008.
520 $a Spatial patterns in the distribution of organisms and temporal changes in populations are often driven by environmental variation. However, dramatic shifts in community state may also occur with little change in the underlying environment. For example, adjacent sections of a similar landscape can support very different communities and communities can shift abruptly through time from one state to another with little or no accompanying environmental change. These patterns may represent threshold responses to the environment, or they may represent alternative stable states, in which positive feedbacks maintain different community states under the same environmental conditions.
520 $a I explore how positive feedbacks create dramatic community shifts across space and through time using marine benthic communities as a case study. I focus on reefs which can support either a macroalgal dominated community or one characterized by high densities (>10,000 m-2) of a filter feeding sea cucumber. I combine field experiments, mathematical modeling and analysis of long term monitoring data to determine what mechanisms maintain the distinct community states, seeking to explain both the sharp spatial transitions between these communities and the abrupt temporal shifts in state observed in the data.
520 $a I found that the sea cucumbers engage in intraguild predation, competing for space with macroalgae but also consuming algal spores. Mathematical models illustrate that when predation on spores is strong, alternative stable states are possible. Spatial models reveal that intra-guild predation will lead to sharp spatial transitions between communities, even with gradual or no environmental variation. This mechanism can explain the observed spatial segregation between the two taxa. I also explore a range of potential explanations for the two most dramatic state switches observed in the past 25 years. A period of low waves appears to have reduced the competitive ability of algae, allowing a switch into the sea cucumber dominated state. A switch back to macroalgal dominance was then caused by the appearance of a previously absent predator. Understanding these dramatic shifts in community state is a pressing challenge for ecology, and can be best addressed by research that focuses on the underlying mechanisms and applies a range of ecological techniques.
590 $a School code: 0035.
650 4 $a Biology, Ecology. $3 1017726
650 4 $a Biology, Oceanography. $3 783691
690 $a 0329
690 $a 0416
710 2 $a University of California, Santa Barbara. $b Ecology, Evolution & Marine Biology. $3 1683731
773 0 $t Dissertation Abstracts International $g 70-01B.
790 1 0 $a Holbrook, Sally J., $e advisor
790 1 0 $a Schmitt, Russell J. $e committee member
790 1 0 $a Nisbet, Roger M. $e committee member
790 1 0 $a Reed, Daniel C. $e committee member
790 $a 0035
791 $a Ph.D.
792 $a 2008
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3342040