Ecology of Seagrass Seeds and Seagrass Dispersal Processes

Orth, Robert J.; Harwell, Matthew C.; Inglis, Graeme J.

doi:10.1007/1-4020-2983-7_5

Cited by 60 publications

(74 citation statements)

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“…Eelgrass populations grow through rhizome expansion and seed dispersal (Ackerman 2006;Orth et al 2006a). Clonal stands develop through vegetative propagation.…”

Section: Methodsmentioning

confidence: 99%

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Restoring Resiliency: Case Studies from Pacific Northwest Estuarine Eelgrass (Zostera marina L.) Ecosystems

Thom

Diefenderfer

Vavrinec

et al. 2011

Estuaries and Coasts

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An objective of many ecological restoration projects is to establish resilience to disturbances. Eelgrass (Zostera marina L.) represents a useful model to evaluate resilience because the plant community is dominated by one species and the estuarine environment is dynamic. Our studies of planted and reference plots used shoot density monitoring data from three projects spanning 3 to 12 years. Data show that eelgrass can recover from major shifts in pond position and shape on sandflats, as well as natural disturbances causing >20-fold change in density. However, cumulative effects of multiple stressors on unestablished plantings suggest algal blooms of unusual magnitude can tip normally marginal conditions to unfavorable. Thus, potential resilience appears to depend on landscape conditions. A dynamic equilibrium was evinced in even the deepest, lowest-density plantings, probably associated with lightmediated carrying capacity and vegetative belowground production characteristic of the Pacific Northwest. We recommend eight resilience-related planning elements to reduce uncertainties in eelgrass restoration.

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“…Eelgrass populations grow through rhizome expansion and seed dispersal (Ackerman 2006;Orth et al 2006a). Clonal stands develop through vegetative propagation.…”

Section: Methodsmentioning

confidence: 99%

“…In the systems that we studied, low levels of flowering may constrain gene flow even within a discrete patch. Although seed deposition is highly localized (∼1 m from parent shoot), floating flowering shoots and other mechanisms can spread seeds as far as 150 km (Orth et al 2006a;Källström et al 2008).…”

Section: Multiple Stressors and Stable Statesmentioning

confidence: 99%

Restoring Resiliency: Case Studies from Pacific Northwest Estuarine Eelgrass (Zostera marina L.) Ecosystems

Thom

Diefenderfer

Vavrinec

et al. 2011

Estuaries and Coasts

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“…Indeed, Z. japonica in part of its introduced range has been reported to grow better under higher temperatures (Shafer et al 2007; and to be essentially an annual, with almost all new shoots arising from seeds in spring (Harrison 1982b;Harrison and Bigley 1982). In contrast, many reports of Z. marina indicate it to be physiologically limited to the lower intertidal (Thom et al 2003, Moore andShort 2006) with severe bottlenecks in recruitment (Orth et al 2006b;Wisehart et al 2007). These ideas point to the importance of making ecological, not just taxonomic comparisons to distinguish pre-adaptation and Darwin's naturalization hypothesis, so our second objective was to examine seasonal variation in growth and reproduction.…”

Section: Introductionmentioning

confidence: 90%

Congener comparison of native (Zostera marina) and introduced (Z. japonica) eelgrass at multiple scales within a Pacific Northwest estuary

et al. 2009

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A congener comparison of native (Zostera marina) and introduced (Zostera japonica) eelgrasses was conducted in Willapa Bay, Washington, USA. Along intertidal transects, Z. japonica (0.1-1.5 m above mean lower low water [MLLW]) occurred above Z. marina (\0.6 m MLLW). Both species declined in shoot length at higher elevation, but Z. japonica was always shorter (20 vs. 100 cm) and occurred at higher shoot density ([3,800 vs.\360 m -2 in Z. marina). Z. japonica exhibited greater seasonal variation in biomass, with increases supported by both sustained asexual reproduction (rhizome branching) and recruitment from seeds (30 vs.\5% in Z. marina). Z. japonica's successful invasion appears related to small size and high reproductive output, allowing it to spread quickly in a variable and stressful intertidal environment where competitive effects are low. Based on interannual changes in abundance, the native eelgrass has also recently increased in Willapa Bay, and one hypothesis involves ''engineering'' of suitable habitat at higher tidal elevations by Z. japonica.

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“…Two hypotheses were suggested to explain the unexpected increase in seagrass cover following the bloom: (1) an increase in sexual recruitment following a disturbance caused by extreme light limitation (cf. Duarte et al 2006;Orth et al 2006b) or (2) an increase in overall light availability despite the brown tide event. Tier 3 monitoring revealed either a decrease (widgeon grass) or no change (eelgrass) in sexual reproduction between 2007 and 2009; however, the considerable increase in widgeon grass cover at shallow depths and the significant bed expansion both suggest an increase in light availability between years.…”

Section: Relevance Of a Tiered Approachmentioning

confidence: 99%

Integrating Scales of Seagrass Monitoring to Meet Conservation Needs

Neckles

Kopp

Peterson

et al. 2011

Estuaries and Coasts

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We evaluated a hierarchical framework for seagrass monitoring in two estuaries in the northeastern USA: Little Pleasant Bay, Massachusetts, and Great South Bay/Moriches Bay, New York. This approach includes three tiers of monitoring that are integrated across spatial scales and sampling intensities. We identified monitoring attributes for determining attainment of conservation objectives to protect seagrass ecosystems from estuarine nutrient enrichment. Existing mapping programs provided large-scale information on seagrass distribution and bed sizes (tier 1 monitoring). We supplemented this with baywide, quadrat-based assessments of seagrass percent cover and canopy height at permanent sampling stations following a spatially distributed random design (tier 2 monitoring). Resampling simulations showed that four observations per station were sufficient to minimize bias in estimating mean percent cover on a bay-wide scale, and sample sizes of 55 stations in a 624-ha system and 198 stations in a 9,220-ha system were sufficient to detect absolute temporal increases in seagrass abundance from 25% to 49% cover and from 4% to 12% cover, respectively. We made highresolution measurements of seagrass condition (percent cover, canopy height, total and reproductive shoot density, biomass, and seagrass depth limit) at a representative index site in each system (tier 3 monitoring). Tier 3 data helped explain system-wide changes. Our results suggest tiered monitoring as an efficient and feasible way to detect and predict changes in seagrass systems relative to multi-scale conservation objectives.

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Ecology of Seagrass Seeds and Seagrass Dispersal Processes

Cited by 60 publications

References 0 publications

Restoring Resiliency: Case Studies from Pacific Northwest Estuarine Eelgrass (Zostera marina L.) Ecosystems

Restoring Resiliency: Case Studies from Pacific Northwest Estuarine Eelgrass (Zostera marina L.) Ecosystems

Congener comparison of native (Zostera marina) and introduced (Z. japonica) eelgrass at multiple scales within a Pacific Northwest estuary

Integrating Scales of Seagrass Monitoring to Meet Conservation Needs

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