Global seagrass habitats are threatened by multiple anthropogenic factors. Effective management of seagrasses requires information on the relative impacts of threats; however, this information is rarely available. Our goal was to use the knowledge of experts to assess the relative impacts of anthropogenic activities in six global seagrass bioregions. The activities that threaten seagrasses were identified at an international seagrass workshop and followed with a web-based survey to collect seagrass vulnerability information. There was a global consensus that urban/industrial runoff, urban/port infrastructure development, agricultural runoff and dredging had the greatest impact on seagrasses, though the order of relative impacts varied by bioregion. These activities are largely terrestrially based, highlighting the need for marine planning initiatives to be co-ordinated with adjacent watershed planning. Sea level rise and increases in the severity of cyclones were ranked highest relative to other climate change related activities, but overall the five climate change activities were ranked low and experts were uncertain of their effects on seagrasses. The experts' preferred mechanism of delivering management outcomes were processes such as policy development, planning and consultation rather than prescriptive management tools. Our approach to collecting expert opinion provides the required data to prioritize seagrass management actions at bioregional scales.

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Seagrasses are important marine ecosystems situated throughout the world's coastlines. They are facing declines around the world due to global and local threats such as rising ocean temperatures, coastal development and pollution from sewage outfalls and agriculture. Efforts have been made to reduce seagrass loss through reducing local and regional stressors, and through active restoration. Seagrass restoration is a rapidly maturing discipline, but improved restoration practices are needed to enhance the success of future programs. Major gaps in knowledge remain, however, prior research efforts have provided valuable insights into factors influencing the outcomes of restoration and there are now several examples of successful large-scale restoration programs. A variety of tools and techniques have recently been developed that will improve the efficiency, cost effectiveness, and scalability of restoration programs. This review describes several restoration successes in Australia and New Zealand, with a focus on emerging techniques for restoration, key considerations for future programs, and highlights the benefits of increased collaboration, Traditional Owner (First Nation) and stakeholder engagement. Combined,

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The long-term changes of tropical intertidal seagrass, mainly Halodule uninervis and Halophila ovalis meadows and their relationship to climate are poorly documented. Developing a greater understanding of the effects of climate on seagrass meadows is critical for estimating the effects of future climate change scenarios. Here we document the temporal dynamics of coastal intertidal seagrass in tropical northeast Australia over 16 yr of detailed monitoring. This study is the first to directly relate such change to long-term climate variability in the Indo-Pacific region and southern hemisphere. Regression modelling was used to relate seagrass biomass and meadow area measurements to climate data. The aboveground biomass and area of the meadow were correlated with the interacting factors of air temperature, precipitation, daytime tidal exposure and freshwater runoff from nearby rivers. Elevated temperature and reduced flow from rivers were significantly correlated (R 2 = 0.6, p < 0.001) with periods of lower seagrass biomass. Results of this study have important implications for the long-term viability of seagrasses with regard to climate change scenarios. Modelling of our findings indicates that future higher temperatures could be detrimental to Indo-Pacific intertidal, coastal and estuarine seagrass meadows.KEY WORDS: Climate change · Global warming · Halophila ovalis · Halodule uninervis · Temperature · Rainfall · Indo-Pacific · Queensland · Australia Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 422: [93][94][95][96][97][98][99][100][101][102][103] 2011 been lost at an unprecedented rate from a variety of anthropogenic influences (Waycott et al. 2009). Predictions of the influence of climate change scenarios on seagrass (Short & Neckles 1999, Harley et al. 2006, Poloczanska et al. 2007, Waycott et al. 2007) are largely based on incidences of seagrass loss associated with extreme weather (Cardoso et al. 2008, Micheli et al. 2008 as reported in short-term experimental studies (Campbell et al. 2006). Long-term studies directly measuring seagrass changes and how they are correlated with climate are rare. Such studies are restricted to the Mediterranean Sea and coastal areas of Florida (Marba & Duarte 1997, Tomasko et al. 2005; no similar studies have been reported for the tropical Indo-Pacific region.Throughout the Indo-Pacific region, turbid estuarine and coastal environments commonly contain abundant and productive intertidal seagrass meadows dominated by the small colonising floral species of Halodule uninervis (Forssk.) Aschers., 1882 and Halophila ovalis (R.Br.) J. D. Hooker, 1858, Coles et al. 2003. Such meadows are often spatially expansive , Coles et al. 2003 and are particularly important food sources for dugong Dugong dugong and green turtles Chelonia mydas (Bjorndal 1985, Preen & Marsh 1995. The intertidal and coastal location of these meadows makes them susceptible to large climatic events, such as flooding , Campbell & McKenzie 2004, drought...

Tropical seagrass decline and recovery from severe storm impacts was assessed via quarterly measurements of seagrass biomass, species composition and experimental investigations of recovery in north Queensland. Shallow and deep seagrass meadows suffered major declines. Significant recovery in the two years following loss only occurred at deeper sites. Halophila spp. in deep water areas had a high capacity for recovery through the availability of seed banks. In contrast, the shallow species did not recover quickly from experimental disturbance, had poor seed reserves and relied on asexual propagation. The potential for shallow species to recover rapidly from widespread losses was limited as seed banks were limited or non-existent. Understanding inter- and intra-specific differences in seagrass recovery and how this interacts with location is critical to predict the consequences of climate events to tropical seagrasses. This is especially important as more frequent severe storms are predicted as a consequence of climate change.

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