Ocean Bees! The next wave of Research
By Miles Bolton
It can be assumed that most folks understand the dynamics of pollination when it comes to bees and terrestrial flora; however the same cannot be said for marine flora. This is an understandable phenomenon considering that until recently, we’ve had no need to have a general understanding of marine pollination processes given the fact that we don’t conduct agriculture on a large scale underwater.
When it comes to marine flora, hydrophily, aka pollen dispersal by means of currents and tides, is the preferred vector for pollination. Terrestrial plants have a vast array of options by comparison: wind, animals, hydrophily, etc. Animal driven pollination is the most celebrated method as it has a much higher success rate than random dispersal methods (wind,water) and also animal pollinators are just too darn charismatic. Bees, Butterflies, Hummingbirds, and Bats are just some of the beloved pollinators that play a vital role in terrestrial ecosystems. Until now, marine ecosystems have been thought to be devoid of any animal pollinator equivalent much less a comparatively lovable counterpart to terrestrial pollinators.
In August, 2016 Brigitta van Tussenbroek, an accomplished seagrass researcher and tenured professor at the National Autonomous University of Mexico discovered that small crustaceans and invertebrate fauna actively pollinate Turtle Grass(Thalassia testudinum)- a common variety of seagrass in tropical climates, mostly found in the Carribean Sea and the Gulf of Mexico. Although a slew of articles were published about her groundbreaking discovery, I’ve met few people who were aware of it and felt like her study went largely unnoticed beyond the confines of the science community. Without fear of hyperbole, this study given proper credit would surely establish Dr. Tussenbroek as one of the premier researchers in the realm of marine ecology.
To unveil such a fundamental phenomenon in 2018 is nothing short of groundbreaking, literally revolutionizing the way we think about marine ecology, thus opening up new avenues for research as it can be safely assumed that Turtle Grass isn’t the only species pollinated by marine fauna.
HOW IT HAPPENED
Tussenbroek discovered aquatic animal driven pollination by setting up a series of aquarium experiments, where collected invertebrate fauna and turtle grass were observed together over a period of 2 years. She found that a number of larvae, polychaetes (marine worms), and small crustaceans had pollen grains attached to their exoskeleton and would successfully transport the pollen between male and female reproductive shoots to initiate pollination.
Ocean pollinators are attracted to the male flowers as they feast on mucilage-laden pollen grains, pollen grains then gets stuck to their body thanks to the mucilage before they get swept away by water movement. The female flowers of turtle grass are adept, at snagging these little critters out of the current with their sticky, tentacle like stigmas (ovule producing part of flower) so they can collect the pollen grains directly from the temporarily captured fauna.
The collected pollen grains induce germination, leading to the formation of pollen tubes to transport the male gametes to the ovary. Tussenbroek has branded this newly discovered form of pollination as zoobenthophily, meaning pollination facilitated by organisms that live in, near, or on the sea-bottom. While Turtle Grass is capable of cloning itself, zoobenthophily and hydrophily are important mechanisms for increasing genetic diversity among the species.
WHY IT MATTERS
Turtle Grass has great ecological value as it is considered an ecosystem engineer; any organism that is capable of creating, destroying, or modifying habitats. Turtle Grass creates extensive seagrass meadows that provide food and shelter for a plethora of marine organisms, the most charismatic of which being sea turtles whose feeding habits have given this seagrass variety its name. A variety of mollusks, sea urchins, parrotfish, crabs, and polychaetes are examples of less photogenic beneficiaries of these seagrass meadows as well. In addition to providing food and shelter, Turtle Grass helps stabilize marine ecosystems by filtering the surrounding water and sequestering carbon dioxide therefore reducing the potential for nutrient pollution aka eutrophication. Although Turtle Grass can suffer from periodic dieback events in the Florida Bay Area, Turtle Grass populations remain stable overall.
So if Turtle Grass populations remain stable, so what, what’s next? Yeah the whole ocean pollination discovery is totally copastetic and groundbreaking and all that noise but how does it apply to the grave environmental problems we face today. Well, as I mentioned before this is most likely just one of many examples of marine flora benefitting from animal driven pollination or Zoobenthophily. The next step would be to study other seagrass species to determine whether or not they also benefit from Zoobenthophily.
Eelgrass(Zostera marina), the closest ecological equivalent to Turtle Grass in temperate zones, would be next logical species to study. Eelgrass is a true equal to Turtle Grass in the sense that it provides the same ecosystem services provided by Turtle Grass (Food/Shelter, Filtration, Carbon Sequestering), the only difference lies in their habitat preference.
Unlike Turtle Grass, Eelgrass populations aren’t in good shape. Over the past 30 years ¼ million acres of eelgrass have been lost worldwide, this downward slope places eelgrass in the similar territory to coral reefs, tropical rainforests, mangroves as one of the most threatened ecosystems on earth.
There are a number of eelgrass restoration projects dispersed along the U.S Atlantic Coast however their efforts have had limited results thus far. Eelgrass restoration projects have generally experienced recruitment rates less than 10% following transplantation, as anthropogenic nutrient pollution has made it difficult for transplanted individuals to persist.
Future studies on Zoobenthophily has the potential to offer clues on how to develop more efficient eelgrass restoration methods. I’ll abstain from ranting about all the potential ways such a discovery with Eelgrass could influence future restoration methods as such a rant warrants it’s own article.
Stay tuned for the next wave.