Thresholds for morphological response to light reduction for four tropical seagrass species

Collier, Catherine; Adams, Matthew; Langlois, Lucas; Waycott, Michelle; O’Brien, Katherine R.; Maxwell, Paul; McKenzie, Len J.

doi:10.1016/j.ecolind.2016.02.050

Cited by 63 publications

(34 citation statements)

References 40 publications

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“…how long before damage occurs. For example, the greater the severity of light reduction, the more likely the disturbance will cause biomass decline and damage (Collier et al, 2016;Lavery et al, 2009), and impact seagrass at medium to large scales. If the intensity is low, damage is more likely to be reversible: in some cases, acclimation may even be possible (Ralph et al, 2007).…”

Section: Disturbance Characteristicsmentioning

confidence: 99%

“…5). For example, in cool (23°C) conditions, it took 1-4 weeks and 4-7 weeks respectively for 90-100% light deprivation to affect the growth rate of Halodule uninervis and Cymodocea serrulata, but 10-14 weeks and > 14 weeks respectively for shoot density to be affected (Collier et al, 2016). Thus while one month of severe light reduction could be expected to reduce H.uninvervis growth rates, it would take more than three months to affect the shoot density of C.serrulata under these conditions.…”

Section: Disturbance Characteristicsmentioning

confidence: 99%

“…However seagrass response to environmental change is much more difficult to quantify. Numerous empirical studies have shown that seagrass dynamics are affected by interactions between environmental variables, such as temperature, light and the density and diversity of grazers (Christianen et al, 2012;Collier et al, 2016;Duffy et al, 2003;Eklöf et al, 2010;Heithaus et al, 2014), however these relationships are complex, and laboratory or field manipulations are unable to assess interactions between all variables. Simple mathematical models demonstrate that self-sustaining feedbacks have the potential to perpetuate either seagrass presence or absence (Carr et al, 2012;Maxwell et al, 2016;Maxwell et al, 2015), but again these models necessarily account for only a small number of processes which affect seagrass dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Seagrass ecosystem trajectory depends on the relative timescales of resistance, recovery and disturbance

O’Brien

Waycott

Maxwell

et al. 2018

Marine Pollution Bulletin

125

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Seagrass ecosystems are inherently dynamic, responding to environmental change across a range of scales. Habitat requirements of seagrass are well defined, but less is known about their ability to resist disturbance. Specific means of recovery after loss are particularly difficult to quantify. Here we assess the resistance and recovery capacity of 12 seagrass genera. We document four classic trajectories of degradation and recovery for seagrass ecosystems, illustrated with examples from around the world. Recovery can be rapid once conditions improve, but seagrass absence at landscape scales may persist for many decades, perpetuated by feedbacks and/or lack of seed or plant propagules to initiate recovery. It can be difficult to distinguish between slow recovery, recalcitrant degradation, and the need for a window of opportunity to trigger recovery. We propose a framework synthesizing how the spatial and temporal scales of both disturbance and seagrass response affect ecosystem trajectory and hence resilience.

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Section: Disturbance Characteristicsmentioning

confidence: 99%

Section: Disturbance Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Seagrass ecosystem trajectory depends on the relative timescales of resistance, recovery and disturbance

O’Brien

Waycott

Maxwell

et al. 2018

Marine Pollution Bulletin

125

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show abstract

“…Seagrass is a key ecosystem of the GBR (Coles et al 2015) that provides habitat and food for marine animals, including iconic megafauna such as turtles and dugongs, along with a range of other ecosystem services. Criteria for seagrass persistence are typically represented as a minimum average annual benthic light requirement (Erftemeijer and Lewis 2006); however in practice, light requirements vary between species, and also depend on the duration of light deprivation (Collier et al 2016). For example, a short-duration (4-12 weeks of low light) light threshold of 6 mol photons m -2 d -1 has been proposed for the common species Zostera muelleri (Chartrand et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Towards Ecologically Relevant Targets: Impact of flow and sediment discharge on seagrass communities in the Great Barrier Reef

Lambert¹,

Adams²,

Collier³

et al. 2019

El Sawah, S. (Ed.) MODSIM2019, 23rd International Congress on Modelling and Simulation.

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Catchment degradation causing increased sediment flow is one of the key stressors facing Great Barrier Reef (GBR) habitats. Ecologically relevant targets (ERTs) for sediment and nutrient loads have been previously proposed based on seagrass light requirements, the next step is to connect these to ecological response. The overarching goal of the present work is to recommend preliminary thresholds that can be used in the development of more refined ERTs. To achieve this, we perform statistical analysis on datasets for catchment flows and sediment loads and condition of the adjacent seagrass habitat, to identify what might be the direct impacts of catchment discharge on seagrass and the associated timescales of ecological response. Our case study focuses on Cleveland Bay, which is located in the central GBR, and has important seagrass habitat that is affected by discharge from the Burdekin River. Annual monitoring of seagrass biomass and area has been undertaken since 2007. We compare these ecological time-series with data for Burdekin River annual flow and total sediment load from 2005 onwards. Annual Burdekin River flow varied by nearly 40-fold within the 2005-2018 study period, and declines in biomass and area of both subtidal and intertidal seagrasses were associated with high flows and loads from the Burdekin. Subtidal seagrasses appeared more sensitive to changes in catchment discharges than intertidal seagrasses, exhibiting a 3 year timeframe for recovery, following high annual flows and loads. Based on our results, a linear model relating change in seagrass biomass to Burdekin River metrics was used to calculate predicted thresholds below which seagrass biomass was likely to increase, and above which biomass was likely to decline. For seagrass area, a growth threshold, below which seagrass area expanded; and a decline threshold, above which seagrass area fell, were defined for annual Burdekin River flow, and sediment load. Overall these thresholds provide the first steps towards refining ERTs based on ecological condition, which can directly inform the management of the GBR to protect its iconic seagrass habitats and associated communities. The next step is to examine whether the relationship between river discharge and sediment load was the primary cause of seagrass decline.

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“…Taking into account these environmental fluctuations, seagrass require physiological, and morphological adaptations to withstand a wide range of light stress. Tolerance to light stress often varies among seagrass species (Orth et al, 2006; Petrou et al, 2013; Collier et al, 2016). Therefore, new knowledge on the light thresholds and the cellular mechanisms for seagrass survival under light stress can inform better management of seagrass habitats.…”

Section: Introductionmentioning

confidence: 99%

Proteome Analysis Reveals Extensive Light Stress-Response Reprogramming in the Seagrass Zostera muelleri (Alismatales, Zosteraceae) Metabolism

et al. 2017

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Seagrasses are marine ecosystem engineers that are currently declining in abundance at an alarming rate due to both natural and anthropogenic disturbances in ecological niches. Despite reports on the morphological and physiological adaptations of seagrasses to extreme environments, little is known of the molecular mechanisms underlying photo-acclimation, and/or tolerance in these marine plants. This study applies the two-dimensional isoelectric focusing (2D-IEF) proteomics approach to identify photo-acclimation/tolerance proteins in the marine seagrass Zostera muelleri. For this, Z. muelleri was exposed for 10 days in laboratory mesocosms to saturating (control, 200 μmol photons m−2 s−1), super-saturating (SSL, 600 μmol photons m−2 s−1), and limited light (LL, 20 μmol photons m−2 s−1) irradiance conditions. Using LC-MS/MS analysis, 93 and 40 protein spots were differentially regulated under SSL and LL conditions, respectively, when compared to the control. In contrast to the LL condition, Z. muelleri robustly tolerated super-saturation light than control conditions, evidenced by their higher relative maximum electron transport rate and minimum saturating irradiance values. Proteomic analyses revealed up-regulation and/or appearances of proteins belonging to the Calvin-Benson and Krebs cycle, glycolysis, the glycine cleavage system of photorespiration, and the antioxidant system. These proteins, together with those from the inter-connected glutamate-proline-GABA pathway, shaped Z. muelleri photosynthesis and growth under SSL conditions. In contrast, the LL condition negatively impacted the metabolic activities of Z. muelleri by down-regulating key metabolic enzymes for photosynthesis and the metabolism of carbohydrates and amino acids, which is consistent with the observation with lower photosynthetic performance under LL condition. This study provides novel insights into the underlying molecular photo-acclimation mechanisms in Z. muelleri, in addition to identifying protein-based biomarkers that could be used as early indicators to detect acute/chronic light stress in seagrasses to monitor seagrass health.

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Thresholds for morphological response to light reduction for four tropical seagrass species

Cited by 63 publications

References 40 publications

Seagrass ecosystem trajectory depends on the relative timescales of resistance, recovery and disturbance

Seagrass ecosystem trajectory depends on the relative timescales of resistance, recovery and disturbance

Towards Ecologically Relevant Targets: Impact of flow and sediment discharge on seagrass communities in the Great Barrier Reef

Proteome Analysis Reveals Extensive Light Stress-Response Reprogramming in the Seagrass Zostera muelleri (Alismatales, Zosteraceae) Metabolism

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