Issue 40 March 2010 Seagrass-WThe official magazine of the Seagrass-Watch global assessmentatch and monitoring program Seagrass in HOTWater Climate drives Patos Lagoon seagrass Seribu Islands National Park Pangandaran Sanctuary Lyngbya returns to Roebuck Bay Night Watch & UFOs Cyclone Season Impacts Seagrass cycles at Cockle Bay Sea Hares S eagrass-Watch Local eyes Global wise In this issue: In this issue: Article page Hot water, burning seagrass.................2 Patos Lagoon, south Brazil..................4 Cockle Bay, QLD................................6 Cyclone season, QLD.........................8 Burning Lyngbya returns to Roebuck Bay........10 seagrass Pangandaran, Indonesia...................12 Article & photography Len McKenzie Seribu Islands, Indonesia..................13 Night Watch, QLD............................14 Sea hares.........................................16 There is greater than 90% certainty 1.5 that increases in greenhouse From the editors gas emissions have caused most Since seagrasses evolved back into the sea of the global warming since the approximately 100 million years ago, they mid-20th century. International have adapted to a wide range of tolerances, research shows that it is extremely including climate extremes. However, over unlikely that the observed warming the last century, seagrasses have had to cope could be explained by natural with a changing climate occurring at an causes alone.... unprecedented rate. In this issue we present CSIRO 2010 State of the Climate the latest findings from the Seagrass-Watch temperature monitoring and findings from seagrass monitoring where climate appears to be the most significant driver of change. Read about the impacts of Cyclone Ului on the intertidal seagrasses of the Mackay Whitsunday region in Australia, and how climate influences the seagrass and drift algae of Patos Lagoon in southern Brazil. You can also read how over the last 40 years, climate driven cycles have influenced tropical seagrass succession at Cockle Bay. In this issue you'll find articles on the return of Lyngbya to Roebuck Bay (Western Australia), a survey of seagrasses in Pangandaran Sanctuary (Indonesia), and a reassessment of seagrass in the Seribu Islands National Park (Indonesia). You can also read about how some dedicated volunteers monitored their seagrasses at night, observing UFOs among other things. You can even learn about Sea Hares. 2009 ends the world's warmest decade on record. 2009 was also Australia's second warmest year on record since high-quality records began in 1910, and possibly the COVER: Burnt seagrass, Tagaqe, Fiji. globe's 5th warmest year on record (about 0.44°C above the 1961-90 average). The Photographer Len McKenzie Southern Hemisphere set a record in 2009 as the warmest year for that half of the world. ISSN 1441-4236 Although there is a high degree of Intertidal seagrasses (both coastal and Editing & additional text: Len McKenzie, Rudi Yoshida & Richard Unsworth interannual (year-to-year) and decadal reef) are adapted to high air and water Layout & graphic design: Rudi Yoshida & Len McKenzie variability in both global and hemispheric temperatures and desiccation through Recommended citation: McKenzie, LJ,Yoshida, RL & temperatures, underlying this variability is direct exposure to air. Experimental Unsworth, R (Eds) (2010) Seagrass-Watch News. Issue 40, a long-term warming trend that has studies on tropical seagrasses demonstrate March 2010. Seagrass-Watch HQ. 16pp. become strong and persistent over the that the sensitivity is species specific as DISCLAIMER: while all efforts have been made to verify facts, past three decades. Sea surface Cymodocea rotundata, Cymodocea Fisheries Queensland (a service of the Department of Employment, Economic Development and Innovation) takes no temperatures around Australia have serrulata, Halodule uninervis and responsibility for the accuracy of information supplied in increased by about 0.4°C in the past 50 Thalassia hemprichii are more tolerant to Seagrass-Watch News. The views expressed in this magazine are those of the authors and not necessarily those of the years and current sea surface short term (1 to 4 hr) exposures of thermal Queensland Government. temperatures are warmer than they have stress (35 to 45°C) than Halophila ovalis, Seagrass-Watch acknowledges the Traditional been over at least the past 250 years. Zostera capricorni and Syringodium Owners on whose sea country we monitor Climate change scenarios suggest isoetifolium. The experiments also suggest elevated temperature extreme ranges are that photosynthetic condition of all Seagrass-Watch HQ, Northern Fisheries Centre projected to rise between 1.2°C and 4.1°C seagrass species are likely to suffer PO Box 5396, Cairns. Qld. 4870 AUSTRALIA by 2100. Within this framework the irreparable effects from short-term or email: [email protected] impacts of increasing temperatures on episodic changes in seawater seagrasses will be particularly significant temperatures as high as 40 - 45°C. This magazine can be downloaded as a pdf from www.seagrasswatch.org/magazine.html for coastal intertidal and shallow subtidal Ultimately, increased exposure to high NEXT ISSUE OUT JUNE 2010 seagrasses. temperature and/or desiccation can both 2 WWW.SEAGRASSWATCH.ORG The phenomenon known as “burning” of intertidal seagrasses is most likely a response to exposure and/or thermal stress associated with climate conditions... coldest year of monitoring was 2006 followed closely by 2007. Seawater temperature directly affects seagrass metabolism, productivity and reproduction. This in turn can influence the seasonal and geographic patterns of species abundance and distribution. Increasing seawater temperature would result in the distribution of species more 1.5 prevalent in tropical and equatorial waters Mean within canopy temperature anomolies against long-term monthly average ±95%CI expanding to higher latitudes. If mean sea surface temperature increases up to 2°C 1 above ambient, we can also expect there ) C to be a significant impact on species of ° ( y seagrass that survive at the upper limit of l a 0.5 their thermal tolerance. m o Should such an increase in seawater n a temperature occur, we could also expect e r 0 u an increase in the frequency of burning t a r events and possibly a decrease in seagrass e p abundance. Acute stress responses of m -0.5 e t seagrasses to elevated seawater temperatures are consistent with observed reductions in above-ground biomass in a -1 number of locations worldwide with one episode of seagrass loss linked to an El Niño event. Such an impact would also be -1.5 expected to favour a species composition 2004 2005 2006 2007 2008 2009 dominated by Halodule/Halophila due to their faster recovery times and smaller stature limiting their exposure during low lead to the condition known as “burning”. reported 1-3 days in most years when tide. Over the years the Seagrass-Watch extreme temperatures occurred (with the Some may argue that a small increase in program has reported many instances exception of 2009). Extreme temperatures water temperature may be beneficial to when intertidal seagrasses have been have also been reported from other seagrass as metabolic rates increase with observed to be “burnt”. Although seagrass habitats, including fringing reef elevated temperatures. However, research generally restricted to tropical and sub- (e.g. Picnic Bay in 2009) and estuary (e.g. has shown that this does not necessarily tropical regions, it is not an isolated Sarina in 2006). The most southern translate into an increase in shoot density phenomenon, and has been observed location to report extreme temperature and shoot size (denser meadows) because across several countries, species and events was Rodds Bay in the Southern other factors, such as available light, may intertidal seagrass habitats. In response to GBR in 2008. be limiting. a lot of reports of burning in 2002, which In general, seagrass “burning” was So what can we do? Mitigation of climate coincided with coral bleaching events on observed when temperatures of up to change is a key strategy, however as some the Great Barrier Reef (GBR) and 10°C above the seasonal average climate change is inevitable, it is essential throughout the Indo-Pacific, Seagrass- occurred, especially during low spring to protect and enhance seagrass resilience Watch implemented in situ (within tides and midday solar exposure. During to climate change impacts. So by canopy) temperature logging in these events seagrasses may be exposed managing impacts that reduce resilience September 2003 across Queensland. to elevated seawater temperatures for (eg water quality and light availability), Extreme temperature (40 - 42°C) events periods of 3 to 4 hours. and continued monitoring to evaluate the have been recorded on many occasions Results from the in situ temperature success of management performance, we since monitoring was initiated. These monitoring have also shown that the can ensure our seagrasses survival. events occurred during spring tides when warmest year of monitoring was 2009, Refs: meadows were either exposed to air or with the greatest monthly mean Bureau of Meteorology 2010 Annual Australian Climate Statement 2009 Campbell et al. 2006 Journal of Experimental Marine Biology and Ecology 330: 455468. submerged up to 1.5m. Coastal locations temperature anomaly of +1.12°C (above Waycott et al. 2007 Chpt 8 in Climate Change and the Great Barrier Reef such as Yule Point in the Far North the 2003-2009 average) in August. The MARCH 2010 3 Brazil The "Lagoa dos Patos", in the Brazilian state of Rio Grande do Sul, is the largest lagoon in Brazil and the second largest in Patos South America. The lagoon is 290 km long and up to 64 km wide, with an area of more than 10,100 square km. Lagoon Photo courtesy of NASA Climate variability and the state of 10 km PATOS LAGOON Article by Margareth da Silva Copertino ESTUARY seagrasses Photography Cíntia Barenho & Dimas Gianuca Marshes Shallows (<1.5m) with or without Ruppia Deeper open waters (1.5 - 5m) 32° Channels (>6m) Atlantic Ocean Drift algae, composed mainly by Ulva intestinalis and U.