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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, Elizabeth “Z” Lacey writes about her experiences in the long-term monitoring project in the seagrass beds of South Florida under the direction of Dr. Jim Fourqurean.

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By Elizabeth “Z” Lacey

During my own Ph.D. research for the past five years, I have been doing long-term monitoring of the over 18,000 km2 of seagrass beds in south Florida as part of the ongoing research in the Fourqurean Seagrass Ecosystems Research Lab (http://www2.fiu.edu/~seagrass/).  Seagrass species present include: Manatee grass Syringodium filiforme, Turtle grassThalassia testudinum, Shoal grass Halodule wrightii, Widgeon grass Ruppia maritima, Johnson’s seagrass Halophila johnsonii, Paddle grass H. decipiens and Star grass H. englemanni.  This is a similar list to the one Brooke Landry reported during her vacation in the Bahamas in a previous blog post.  Compared to the 50-60 seagrass species possible, our diversity is relatively low.  With long-term data on seagrass density and nutrient content, Dr. Jim Fourqurean and fellow researchers are able to determine how these seagrass beds are changing over time and what these changes may indicate for overall seagrass bed health.

 FKNMS permanent seagrass monitoring sites (sites located in the Dry Tortugas are not shown).

 Long-term monitoring site Photo by N. Blinick.

 My dive buddy Kirk Gastrich and I complete a seagrass survey at one of the long-term monitoring sites.  Photo by N. Blinick.

Changes in seagrass beds will also have important impacts to the diversity of species that use them for habitat, feeding grounds, refuge and as an important corridor between mangrove and coral reef habitats.  While our seagrass diversity may be limited, there are a multitude of important fish, crustacean and other species supported within these ecosystems.  It is estimated that Florida seagrass beds provide ecological services worth over $40 billion US each year (http://www.dep.state.fl.us/coastal/news/articles/2011/1103_Seagrass.htm).  In addition to the photos of stingrays and sea turtles I posted in my other World Seagrass Association blog entry about my work in Akumal, Mexico, there are a wide diversity of animals that can be seen on any given dive in the seagrass beds of South Florida.  But rather than bore you with my prose, why don’t I let the pictures speak 1,000 words (or many thousands when it comes to the number of diverse species supported in tropical seagrass beds!).

 Caribbean Reef Squid (Sepioteuthis sepioidea). Photo by Captain K. Gastrich.

 Barracuda (Sphyraena barracuda) Photo by Z. Lacey

 Grouper, an important commercial species, spotted in the seagrass bed.  Photo by J. Sweatman

 Sea urchin using turtle and manatee grass to camouflage itself in the seagrass bed. Photo by Z. Lacey

 

Octopus inside a pipe positioned in the seagrass bed to hold a channel marker—you never know what you’ll find when you are observant while snorkeling in a seagrass bed! Photo by Z. Lacey

            These photos are just a few of the many, MANY species that can be found in Florida seagrass beds.  On a recent field trip with my Introduction to Marine Biology students at Florida International University, we caught other animals like moray eels, batfish and sea robins!  In honor of today being International Day for Biodiversity, I invite you to get into the water and spend some time in the seagrass beds.  If you aren’t lucky enough to live near some of these magical ecosystems, then on next vacation you have I invite you to head on down to the Florida Keys and enjoy the diversity of life that seagrass beds support.  These are the things that keep me excited about working in marine ecosystems as I prepare to defend my Ph.D. in just a few short weeks!

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.

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