The Eye of the Beholder: In Support of the Gulf Toadfish

Charisma comes at a cost. Whales, dolphins, and seals have captured the attention of millions for generations, and with time hunting pressure has morphed into abject reverence (sometimes to the same mortal end). I am by no means immune to the pull of the leviathan. My fascination with humpback whales has driven my life choices for over a decade, and even now I am planning our 2019 fieldwork at the Five Finger Lighthouse to keep our studies of whale communication moving forward. I am also not naive, however, to the great myriad of other life on this planet. In my postdoc at Cornell’s Bioacoustics Research Program (BRP) I’m working closely with Dr. Aaron Rice who is opening my eyes to a wide range of spectacular creatures.

Starting with the humble toadfish.

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Gulf toadfish (Opsanus beta). My glorious study species. -Photo by A. Rice

Toadfish are a sound producing benthic ambush predator (hide in the mud making breeding sounds, and later BAM jump out and grab a meal). They can be found throughout Gulf Coast, and in particular I’ve been listening to them in the estuaries of the Florida Everglades.

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Florida Bay is rich with mangrove islands and pelicans.

Male gulf toadfish produce an amazing sound often referred to as a “boatwhistle” (listen below). This is extremely important for my purposes, as I am using a series of hydrophones widely distributed throughout the Florida Bay Estuary in order to (a) detect cool fish sounds like the toadfish and (b) investigate whether toadfish alter their calling behavior in response to conditions in the estuary.

See, the estuaries in Florida Everglades are not what they once were. Farmers needed water to keep crops alive; new settlers needed land in which to build (settling on a gently sloping swamp was ‘unappealing’ to say the least) – and so the massive re-routing of freshwater in South Florida began, and with time it continued until the once brackish water became hyper-saline and a once rich estuary grew unrecognizable. Now, resource managers are working to bring freshwater back, and are tasked with figuring out how these changes in water flow impact the critters who live here, and how (or if) the estuaries can be restored.

Enter our vocal fish. Toadfish have a few qualities that potentially make them a good (if not  obviously charismatic) species for ecosystem monitoring. They nest in estuaries, and males stick to their nest sites during the breeding season. They are resilient to a wide range of oceanographic conditions, and – importantly – the males call predictably and loudly throughout the breeding season.

 

 

My aim is to see if these muddy little chatterboxes are a good indicator of overall ecosystem health. This is likely because, beyond being easy to listen to, toadfish are mid-level predators. They are important in terms of eating the little guys (crabs, shrimp, small bottom fishes etc), but they are also a potentially important prey species (dolphins eat lots of toadfish). If toadfish are responding to changes in water quality, it’s highly likely that there are shifts up and down the food web.

For now, I’ve got ears in the subtropics listening to the songs of fish, but for our next field trip we hope to be more active participants as we playback the sounds of toadfish to the predators of Florida Bay.  They may not be as flashy as a humpback whale, but you know what they say: beauty is in the eye of the beholder.

 

PS- I didn’t manage to get a toadfish on video- but I did spend some lovely time with this ray when I was changing our hydrophones in Bob Allen Key!

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