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22nd May is International Day for Biodiversity and the theme for 2012 is Marine Biodiversity. In celebration, we will be featuring a series of articles on seagrass. This week, Brooke Landry writes about her seagrass explorations while on vacation in Freeport on Grand Bahamas Island.
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Photos and text by Brooke Landry

As a dedicated seagrass ranger, I can’t go on vacation anywhere near the ocean without treating my time there as an underwater exploratory mission. Most recently, I visited Freeport on Grand Bahamas Island, where my mother and I foolishly purchased a timeshare several years ago. One of the true pleasures of vacationing in this spot is the exquisite seagrass bed just 40 or so meters off the beach. Owning a timeshare here means that I can do a repeat sampling of sorts and I’m happy to say that I’ve seen very little change in the bed over the past six years.

The bed is composed of what you’d expect in the clear, shallow, oligotrophic waters of the Bahamas. It’s dominated by Thalassia testudinum with Halodule wrightii and Syringodium filiforme filling in some of the gaps. There’s also a good supply of macroalgae, mostly calcareous greens including Halimeda, Penicillus, and Acetabularia. The grass is fairly dense but patchy and although it’s subject to some disturbance from the rent-by-the-hour jet skis, I have seen neither an expansion nor a decline in the grass itself. What I have seen is an increased number of Diadema antillarum (yah!). Although there is very little coral interspersed in this seagrass bed, there are cinderblocks and as it so happens, long-spined sea urchins love to hide in cinderblocks. I’m assuming the blocks at one time secured buoys for the swim net or served as tie-downs for jet skis, but now there are several just randomly abandoned throughout the bed. In fact, I planned to complain to the resort management about cleaning them up until I realized they were serving as urchin refuge.

The beach with seagrass shadow in the background.

Other urchins, mostly West-Indian Sea Eggs, under the mistaken impression that they were invisible because of the dead seagrass, sponges, and random children’s toys attached to their tests, were everywhere in this particular grass bed. Literally, everywhere. It’s an interesting and beautiful sight to see.

On this most recent trip I also spotted a couple of cow-nosed rays swimming peacefully together, just a meter from unsuspecting and oblivious swimmers. This is the kind of thing I generally like to point out to people, but I’ve grown wary of doing so over the years because, as it turns out, not everyone thinks sea critters are as cool as I do. In fact, most people completely freak out at the notion of being in the water with other living things. I’ve seen swimmers go berserk because their feet touched seagrass. Grass!!! Not a spiny urchin or something that could, given the inclination, bite you, but grass! I’m not even kidding. So I chose to let them swim in oblivion and savored the grace of the rays by myself.

In addition to sting rays, octopi, and urchins that are welcome in any healthy seagrass bed in the Bahamas, I saw one not-so-welcome inhabitant: a Lionfish. Having worked with folks down in North Carolina that did extensive research on Lionfish and their invasive destruction of all things pristine, I’ve seen many Lionfish in captivity. I had never actually seen one out in the water though and it took me by surprise. It was hiding in one of the same cinderblocks that the Diadema were using. I had so many mixed feelings when I noticed it – it was almost like seeing a particularly obnoxious celebrity starlet. It was beautiful and I was awestruck, yet I sort of hated it for its indiscriminately destructive behavior. I wanted it to be gone, but really, it couldn’t help that it was born a Lionfish in the wrong place, so I also felt sorry for it. I named her Pandora and tried not to judge her too harshly, because, after all, there is no species on earth more destructive than my own.

ISBW10 is coming!

Website for ISBW10 is up! click here

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22nd May is International Day for Biodiversity and the theme for 2012 is Marine Biodiversity. In celebration, we will be featuring a series of articles on seagrass. This week, Michael Durako writes about his experiences visiting North Queensland, Australia.
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Photos and text by Michael J. Durako  

During the Fall 2011 semester while on research reassignment from my University, I spent 5 weeks with the Marine Ecology Group (MEG), Fisheries Queensland in Cairns hosted by Dr. Robert Coles, Dr. Michael Rasheed and my former student Katie Chartrand.  During this research visit I focused on assessing changes in leaf spectral reflectance as an indication of seagrass physiological condition, specifically in response to light and desiccation stress. During my visit I was able to sample two relatively pristine sites on Green Island, which is 24 km offshore of Cairns, and several highly-impacted sites in Gladstone Harbour, which is 250 km north of Brisbane.  Before departing for Cairns I was able to assemble a field compatible spectral reflectance system to obtain spectral reflectance measurements in situ using, with the help of Randy Turner and Lance Horn at the University of North Carolina Wilmington Center for Marine Science. The system consisted of a 25m long optical fiber reflectance probe connected through a variable neutral density filter to an Ocean Optics spectrometer with data acquisition controlled by OOI Spectra Suite software via a waterproof external switch and a Panasonic Toughbook PC.

Figure 1. Ocean Optics reflectance setup at Green Island.

 After calibration and testing the reflectance measurement system at the Northern Fisheries Center in Cairns, I set up a short-term shading experiment on Green Island. Shades, which reduced irradiance by 70%, were placed over Halophila ovalis (Hov) and Thalassia hemprichii (Th) located along the inner fringe of a seagrass bed on the south side of the island. The spectral reflectance of leaves of these two species were compared between adjacent full-sun and shaded plots from 0800 to 1400h to determine if this bio-optical characteristic exhibited short-term diurnal changes in high and low light treatments. The resulting reflectance spectra showed significant species, time and treatment differences.

Figure 2. Shade plots over Halophila ovalis and Thalassia hemprichii at Green Island.

 During my visit, I was very fortunate to be able to participate in an aerial (helicopter) seagrass survey trip to Mourilyan Harbor, 80 km south of Cairns. Because of the high tidal range (4 m), turbid water and presence of saltwater crocodiles, aerial survey techniques are broadly used by MEG in their seagrass assessment work in northern Queensland. This aerial approach may be applicable and more efficient for some of our FHAP sampling sites in Florida Bay. We were able to sample 126 sites in about 2 hours and never got our feet wet!

Figure 3. Hovering (altitude 1m) at a seagrass sampling site in Mourilyan Harbor. Helen Taylor of MEG is entering the GPS location of the sampling station on an ARC GIS map using a touchscreen PC. Carissa Fairweather is communicating sampling information to the pilot. My job was to enter the seagrass data on the field datasheets.

 I visited Gladstone Harbor over Sept 27-29th as part of a compliance sampling trip for Queensland Fisheries. During this trip I compared the spectral reflectance of submerged versus exposed seagrasses at four sampling sites: Pelican North, Whiggins, Fisherman’s Island and Pelican South.  Because of the large tidal range (3-4m) and high turbidity, we could only sample during the afternoon low tides. Reflectance data indicated distinct spectra between submerged and exposed leaves for both Zostera capricorni and Halophila ovalis at all four sites (see example spectra in Fig. 6; note separation of spectra from 500-680nm).

 Figure 4. Launching the Fisheries Queensland R/V Halophila at Gladstone Harbor.

Figure 5. Sampling exposed Zostera capricorni at Pelican South, Gladstone Harbor.

 Figure 6. Normalized reflectance of submerged (wet) versus exposed (Dry) Zostera capricorni at North Pelican, Gladstone Harbor.

 Near the end of my visit, I was able to visit Green Island again. My plan was to repeat the shading study in another location on the Island.  However, because of an early occurrence of Irukandji jellyfish, which are extremely venomous, the island was closed to swimming, within an hour of my arrival on the island. One of the resort divers was stung on the lip (she had on a stinger suit) and had to be MediVaced off the island by helicopter. Thus, I had to limit my sampling to only low tide. To make lemonade from lemons, I revised my sampling to be similar to what I had done in Gladstone Harbor.  I compared the spectral reflectance of submerged and exposed Thalassia hemprichii and Halophila ovalis.  The reflectance spectra were again distinct between species and between submersed and emersed shoots, although the differences were more subtle than those at Gladstone.  The results from this short field visit suggest that spectral reflectance provides a rapid assessment method that is sensitive to changes in seagrass physiological condition and it provides another tool in our arsenal of non-invasive physiological ecoindicators.

Figure 7. Measuring spectral reflectance of exposed Halophila ovalis at Green Island.

This year’s theme for International Day for Biodiversity is Marine Biodiversity. The WSA blog will be featuring a series of articles on seagrass this month so watch this space!

Visit the Convention on Biological Diversity page here.

Every fortnight we feature a seagrass meadow from around the world. This week, Elizabeth ‘Z’ Lacey writes about Akumal Bay, an ecosystem in the Caribbean off the coast of Mexico. Z is finishing her Ph.D. at Florida International University in Miami, Florida.
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Photos and text by Z Lacey

I have a confession.  I did not go to Akumal Bay to study the seagrass beds; I went to study the coral reefs.  Before you kick me off the World Seagrass Association blog, hear me out.  I first came to Akumal Bay, Quintana Roo, Mexico to study the return of an important herbivore to the coral reef community BUT I was quickly and irreversibly intrigued by the seagrass beds and the graceful green sea turtles in short order.  Does that redeem me in your eyes, fellow seagrass lovers?

A typical weekend in Akumal Bay: lots of tourists and fishing boats!

But I get ahead of myself.  Let me introduce you to a beautiful place that I’ve been working in for the past four years.  Akumal Bay is located along the MesoAmerican Reef on the Yucatan Peninsula of Mexico and its name means ‘place of the turtles’ in Mayan.  It is a unique environment as it’s one of the few public access beaches for locals as well as serves the surrounding tourist populations coming from Playa del Carmen, Tulum and Cancun.  There are lots of interested stakeholders, which is a challenge for the managers of this important ecosystem.  Incredibly this bay is monitored by the non-governmental organization Centro Ecologico Akumal (www.ceakumal.org) and Director Paul Sanchez-Navarro.  They rely heavily on donations and volunteer stewards to monitor the coral reefs, water quality and abundant turtle population.  To do this they hold turtle walks, give informative lectures in the education center, run a recycling program, provide life jackets/snorkeling vests and many other initiatives, all free of charge to visitors and the residents of the nearby pueblos.

Lush T. testudinum, S. filiforme and H. wrightii bed

A patch of seagrass dominated by the calcareous green algae, Halimeda

Unlike Siti’s last post on the diversity of species to be found in South Sulawesi, the seagrass meadows in Akumal typically consist of just three seagrasses: Thalassia testudinum, Syringodium filiforme and sparse Halodule wrightii intermixed with calcareous green macroalgae.  The seagrass beds are patchy throughout the lagoon from the shoreline to the reef approximately 250 meters offshore.  In some areas of the bay, patch reefs are interspersed throughout the seagrass meadow, providing refuge for fish, urchins and other diverse marine life.

A green sea turtle Chelonia mydas: caught in the act!

A southern stingray Dasyatis americana taking flight over a bed of S. filiforme

Akumal Bay is easily accessible by tourists groups from land as well as those entering on boats via the channel through the adjacent barrier reef.  Part of my research is considering this impact by humans on the seagrass beds and how the herbivores, both sea turtles and fish, have shaped this ecosystem.  Similar to other regions along the Mayan Riviera, this area is experiencing dramatic population growth and even further tourism development.  While the fate of these seagrass beds is unknown, change is inevitable.  CEA is in a difficult position as they try to protect the ecosystem with their limited financial resources while also listening to the needs of the local residents, tour operators and businesses, which rely on the bay mainly for tourism income rather than as a food source.

Yvonne, a volunteer seagrass ranger, harvesting some samples

Volunteers come from all around the world for a three month adventure at CEA and learn skills such as coral reef identification and sea turtle tracking.  Throughout the years I’ve had volunteers from France, Netherlands, Germany, the Philippines and of course Mexico as they assist in my research along with their other volunteer duties.  For some, such as my new friend Yvonne Kleinschmidt pictured here, they were completely unaware of the different types of seagrass before I took them into the field to make them honorary seagrass rangers.  It’s been fun for me to teach workshops on identifying seagrass and macroalgae to the volunteers as part of their reef monitoring training.

 

Hiking to the top of Coba, one of the many Mayan ruins in the region

Before you think it’s all work and no play in Akumal, I have to mention the many Mayan ruins to explore, cenotes to swim in and cities like Playa del Carmen to visit!  Not to mention the amazing local cuisine and fresh fruits and veggies available at the farmer’s market in the town square.  A day off from the field is rich in cultural experiences as well as ecological discovery – another reason I’ve come back to Akumal year after year.  And while I initially studied the coral reefs, you can see how the interesting marine life living within the seagrass beds and the stories waiting to be explored were able to pull me into Akumal Bay!

 

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