Guide to Southern Temperate Seagrasses

Waycott, Michelle; McMahon, Kathryn; Lavery, Paul

doi:10.1071/9781486300167

Cited by 35 publications

(43 citation statements)

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“…Propagules that travel only short distances or remain within the boundary of an existing meadow will have a better chance of remaining in locations likely to be conducive to seagrass growth. However, in the tropics and subtropics, dispersal strategies of marine angiosperms must also operate at scales that explain existing distributions (thousands of kilometres) (Coles et al ., ; McKenzie et al ., ; Waycott et al ., ). Many tropical meadows have persistent viable seed banks, but effective methods must be available for longer distance dispersal and replenishment (even if these mechanisms are rare), simply because of the high number of propagules released from meadows over many years.…”

Section: Discussionmentioning

confidence: 99%

Spatial patterns of seagrass dispersal and settlement

Grech

Wolter

Coles

et al. 2016

Diversity and Distributions

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Aim The movement of propagules among plant populations affects their ability to replenish and recover after a disturbance. Quantitative data on recovery strategies, including the effectiveness of population connectivity, are often lacking at broad spatial and temporal scales. We use numerical modelling to predict seagrass propagule dispersal and settlement to provide an approach for circumstances where direct, or even indirect, measures of population dynamics are difficult to establish. Location Great Barrier Reef, Australia. Methods We used the finite‐element Second‐generation Louvain‐la‐Neuve Ice‐ocean Model (SLIM) to resolve the hydrodynamics of the central Great Barrier Reef and to simulate the dispersal of seagrass. We predicted dispersal and settlement patterns by releasing 10.6 million passive particles representing seagrass propagules at known sites of seagrass presence. We considered two fractions when modelling seagrass dispersal: floating and suspended propagules. Both fractions were modelled using 34 simulations run for a maximum of 8 weeks during the peak seagrass reproductive period, capturing variability in winds, tides and currents. Results The ‘virtual’ seagrass propagules moved on average between 30 and 60 km, but distances of over 900 km also occurred. Most particle movement was to the north‐west. The season (month) of release and source locations of the particles correlated with their dispersal distance, particularly for particles released offshore, with the complex coastal topography impeding movements close to the coast. The replenishment and recovery potential of the northernmost meadows was influenced by southern meadows. Protected north‐facing bays were less likely to receive particles. Main conclusions Our approach advances the conservation and management of marine biodiversity by predicting a key component of ecosystem resilience at a spatial scale that informs marine planning. We show a complex interaction among time, wind, water movement and topography that can guide a management response to improving replenishment and recovery after disturbance events.

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Section: Discussionmentioning

confidence: 99%

Spatial patterns of seagrass dispersal and settlement

Grech

Wolter

Coles

et al. 2016

Diversity and Distributions

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“… Halodule uninervis , Cymodocea rotundata Ascherson (Cymodoceaceae) and Thalassia hemprichii Ascherson (Hydrocharitaceae) are tropical seagrass species widely distributed throughout the Indo-West Pacific while Zostera muelleri Irmisch ex Ascherson (Zosteraceae), (syn Zostera capricorni ) is a tropical to temperate species found in Australia and New Zealand [46]. All four species occur in northeastern Australia and the Great Barrier Reef (GBR).…”

Section: Methodsmentioning

confidence: 99%

Phytotoxicity of Four Photosystem II Herbicides to Tropical Seagrasses

et al. 2013

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Coastal waters of the Great Barrier Reef (GBR) are contaminated with agricultural pesticides, including the photosystem II (PSII) herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50) over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zostera muelleri and Halodule uninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield (∆F/F m ′), indicating reduced photosynthesis and maximum effective yields (Fv/Fm) corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect seagrass meadows of the GBR from further decline.

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“…Definitions of seagrass habitats have been proposed by a number of authors (e.g. Carruthers et al, 2002Carruthers et al, , 2007Short et al, 2007;Waycott et al, 2004Waycott et al, , 2014. Each habitat has a unique suite of environmental conditions that control the amount and variability of light, nutrients, fresh water input and hydrodynamic conditions to which the seagrass is exposed.…”

Section: Attribute 3: Habitat Typementioning

confidence: 99%