A Global Crisis for Seagrass Ecosystems

Orth, Robert J.; Carruthers, Tim J. B.; Dennison, William C.; Duarte, Carlos M.; Fourqurean, James W.; Heck, Kenneth L.; Hughes, Andrew J.; Kendrick, Gary A.; Kenworthy, W. J.; Olyarnik, Suzanne V.; Short, Frederick T.; Waycott, Michelle; Williams, Susan L.

doi:10.1641/0006-3568(2006)56[987:agcfse]2.0.co;2

Cited by 2,565 publications

(1,830 citation statements)

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“…Seagrasses are threatened worldwide (Orth et al, 2006), emphasizing the need for better indicators of their health status and their resilience to disturbance (Duarte et al, 2004). We compared the response of two indicators of seagrass health (i.e., leaf area index as a direct indicator of health versus relative recovery as an indirect indicator of resilience) in different stress levels from hydrodynamic exposure and nutrient availability.…”

Section: Discussionmentioning

confidence: 99%

“…Seagrass meadows can be found in coastal areas worldwide, are defined as keystone species (Zieman et al, 1999) and are known to be highly sensitive to environmental status (Orth et al, 2006). Their development and distribution depend on various conditions such as light and nutrient availability (Duarte, 1991;Grice et al, 1996;Wicks et al, 2009), sufficiently sheltered hydrodynamic conditions and low sediment dynamics (Koch, 2001;Eriksson et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Their development and distribution depend on various conditions such as light and nutrient availability (Duarte, 1991;Grice et al, 1996;Wicks et al, 2009), sufficiently sheltered hydrodynamic conditions and low sediment dynamics (Koch, 2001;Eriksson et al, 2010). Despite their capacity to adapt and to cope to some extent with environmental changes, seagrasses suffer rapid and large-scale losses worldwide, their distribution is declining and their survival threatened (Orth et al, 2006). Anthropogenic influences, causing changes in soil chemistry, nutrient loading, hydrodynamics and sediment dynamics are responsible for the seagrass disappearance over the last 40 years (Orth et al, 2006 and references therein; Waycott et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Despite their capacity to adapt and to cope to some extent with environmental changes, seagrasses suffer rapid and large-scale losses worldwide, their distribution is declining and their survival threatened (Orth et al, 2006). Anthropogenic influences, causing changes in soil chemistry, nutrient loading, hydrodynamics and sediment dynamics are responsible for the seagrass disappearance over the last 40 years (Orth et al, 2006 and references therein; Waycott et al, 2009). …”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Cover versus recovery: Contrasting responses of two indicators in seagrass beds

Soissons

Han

et al. 2014

Marine Pollution Bulletin

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a b s t r a c tDespite being a highly valuable key-stone ecosystem, seagrass meadows are threatened and declining worldwide, creating urgent need for indicators of their health status. We compared two indicators for seagrass health: standing leaf area index versus relative recovery from local disturbance. Disturbance was created by removing aboveground biomass and recording the rate of regrowth for Zostera marina meadows exposed to contrasting wave regimes and nutrient stress levels.Within the experimental period, relative regrowth in gaps was around 50% in most plots, except for the ambient nutrient treatment at the sheltered site, where it exceeded 100%. The two indicators showed an opposite response to disturbance: the higher the standing leaf area index, the lower the relative recovery from disturbance. This conflicting response raises the question on the proper interpretation of such indicators to estimate seagrass health and resilience, and how to ideally monitor seagrass ecosystems in order to predict collapse.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cover versus recovery: Contrasting responses of two indicators in seagrass beds

Soissons

Han

et al. 2014

Marine Pollution Bulletin

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“…Seagrass meadows have been widely acknowledged as highly important coastal systems that support high biodiversity and productivity, and high trapping and storage of nutrients and carbon (Duarte et al, 2010;Hemminga and Duarte, 2000;Orth et al, 2006). Decline of seagrass meadows due to human activity has been reported in recent years throughout the world (Orth et al, 2006;Waycott et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Combined nutrient and macroalgae loads lead to response in seagrass indicator properties

Han

Soissons

Bouma

et al. 2016

Marine Pollution Bulletin

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a b s t r a c t a r t i c l e i n f oExcess nutrients are potential factors that drive phase shifts from seagrasses to macroalgae. We carried out a manipulative field experiment to study the effects of macroalgae Ulva pertusa loading and nutrient addition to the water column on the nitrogen (N) and carbon (C) contents (i.e., fast indicators) as well as on the morphology and structure (i.e., slow indicators) of Zostera marina. Our results showed rapid impact of increased macroalgae and nutrient load on Z. marina C/N ratios. Also, macroalgae addition resulted in a trend of decreasing belowground biomass of seagrasses, and nutrient load significantly decreased above to belowground biomass ratio. Although some morphological/structural variables showed relatively fast responses, the effects of short-term disturbance by macroalgae and nutrients were less often significant than on physiological variables. Monitoring of seagrass physiological indicators may allow for early detection of eutrophication, which may initiate timely management interventions to avert seagrass loss.

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The Evolution of Sulfide in Shallow Aquatic Ecosystem Sediments: An Analysis of the Roles of Sulfate, Organic Carbon, and Iron and Feedback Constraints Using Structural Equation Modeling

Pollman¹,

Swain

Bael

et al. 2017

JGR Biogeosciences

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The generation of elevated concentrations of sulfide in sediment pore waters that are toxic to rooted macrophytes is problematic in both marine and freshwaters. In marine waters, biogeochemical conditions that lead to toxic levels of sulfide generally relate to factors that affect oxygen dynamics or the sediment iron concentration. In freshwaters, increases in surface water sulfate have been implicated in decline of Zizania palustris (wild rice), which is important in wetlands across the Great Lakes region of North America. We developed a structural equation (SE) model to elucidate key variables that govern the evolution of sulfide in pore waters in shallow aquatic habitats that are potentially capable of supporting wild rice. The conceptual basis for the model is the hypothesis that dissimilatory sulfate reduction is limited by the availability of both sulfate and total organic carbon (TOC) in the sediment. The conceptual model also assumes that pore water sulfide concentrations are constrained by the availability of pore water iron and that sediment iron supports the supply of dissolved iron to the pore water. A key result from the SE model is that variations in three external variables (sulfate, sediment TOC, and sediment iron) contribute nearly equally to the observed variations in pore water sulfide. As a result, management efforts to mitigate against the toxic effects of pore water sulfide on macrophytes such as wild rice should approach defining a protective sulfate threshold as an exercise tailored to the geochemistry of each site that quantitatively considers the effects of ambient concentrations of sediment Fe and TOC.

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A Global Crisis for Seagrass Ecosystems

Cited by 2,565 publications

References 5 publications

Cover versus recovery: Contrasting responses of two indicators in seagrass beds

Cover versus recovery: Contrasting responses of two indicators in seagrass beds

Combined nutrient and macroalgae loads lead to response in seagrass indicator properties

The Evolution of Sulfide in Shallow Aquatic Ecosystem Sediments: An Analysis of the Roles of Sulfate, Organic Carbon, and Iron and Feedback Constraints Using Structural Equation Modeling

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