West Indian Manatee (Trichechus manatus)

Meet the manatee capture crew for Wildlife Trust, lead by Buddy Powell (captain Ahab there in the tower).

Buddy and crew recently came to Placencia Lagoon for their second year of affixing radio transmitters to West Indian Manatee. They are hoping to learn the about the distribution and ecology of West Indian Manatees in coastal Belize by tracking their movements over time and analyzing the environmental variables affecting their use of various habitats. As field work goes, this is exciting stuff.

In the first phase of the capture, the boat captain finds a manatee in water of suitable depth and then deploys a net around the animal. "Anchors" (people) then jump into the water to keep the net in place in case the manatee tries to break free or if currents shift its' position.

A secondary net is then deployed inside the first net and the manatee is drug toward the stern of the capture boat. Note that the capture boat has both a tower for spotting manatees and transom in the midships to keep the propeller away from netted manatee. When the manatee is hauled to the rear of the boat, the crew all stand in the back to submerge the stern, the manatee is pulled aboard...

...and then the fun begins.

In this picture a female manatee is laying in the capture vessel and one of the technicians is monitoring CO2 levels in it's breaths. That along with frequency of breaths, heart rate and a variety of other data are collected to ensure the manatee is safe and not overly stressed while on the boat. At that point, the alien abuduction sequence begins.

Tissue samples are taken for DNA analysis. Sonograms are recorded. Body length, fecal samples, tear samples, photographs. In the name of most holy and exact science, everything up to but not including the dreaded anal probe is visited on the manatee...

...which generally seems non-plussed by the whole event.

Finally, a strap and a buoyant radio transmitter are affixed to the tail and the manatee is slid off the stern and back into the lagoon. Last year the Wildlife Trust collared two manatees. This year they refitted the same male for another year of observation. Other manatees were marked in the Southern Lagoon near Gales Point. Biologists will use Yaggi receivers to track the manatees over the course of the next year, monitoring their movements and habitat preferences.

Belize is one of the last bastions of the West Indian Manatee. As a developing nation, the coastline and habitats of the manatee are being gradually altered. Knowing where and how and why the manatee selects habitats will help guide conservation efforts for this most unique animal.

Spiny soft-shelled turtle (Trionyx spiniferus spiniferus)

This is a post about a turtle, but the photo here at the top is of a freshwater mussel survey. These are biologists (Shari, Mike and Diana) from the Illinois Natural History Survey literally crawling in the river shoving their hands into the muck and sand substrate of Kickapoo Creek to find freshwater mussels. Using this technique over the course of a three year study in this stream, we found quite a few freshwater mussels of about fifteen different species.



As you can imagine, this is difficult work. The water is cold. The substrates are hard. Pushing fingers into a river bottom over and over again tends to have a battering effect on the hands, and the hazards are probably too many and unpalatable to mention here. If you need any insights into the mind of a biologist, you should be aware that most of the people in our lab loved doing this job. Certainly I did.

One day in particular, that love was put to the test.

We had covered a large transect with a sand and gravel bottom. We were just about to quit and leave for the next site when I remembered that this stretch of stream also included a substantial side channel. In this channel was a spot where an massive burr oak had toppled into the stream. When it fell, it pulled up its' root ball and left a deep divot that had become permanently filled with water and created a pool.

Standing there at the edge of the side-channel, I immediately saw a small depression in the sand just inside the pool. Hmm. That could be a buried mussel, says I to myself. I strode confidently to the spot, thrust my hand into the depression and drove it down into the muck.

Normally, the feel of a buried mussel is so slick and substantial that even cold-numbed or bruised fingers can distinguish them immediately. In that side-channel pool, I did indeed feel an object buried in that small depression. My fingers closed around it reflexively. "Gotcha!" I was pleased to have found something in this unique habitat and I was curious what it might be. I noticed this specimen seemed unusually large and the texture wasn't quite what I was expecting. Never the less, with a firm steady pull, I was able to begin extracting the mystery mollusk.

Our project was especially concerned with mussel diversity. We wanted to know if the new sewage treatment plant being built on this creek was going to affect its' biodiversity. To that end, we had been tracking nutrients and fish populations and algae growth and all manner of data before and after the plant was open.

It had always been a pleasure to find animals along the creek. One day it might be a massive whitetailed deer bounding out of tall grass, antlers broad enough to form a chair with extra room on either side. The next it might be one of the beavers we found literally everywhere building dams and gnawing trees. Over time was saw innumerable songbirds, raptors, coyotes, reptiles...

...one day I had even stood amazed as a spiny soft-shelled turtled glided to a spot just beside me in a sandy riffle...and shimmied into the sand until it was completely buried and invisible. In the blink of an eye it disappeared leaving just the tip of its' snout visible above the sand. Who would have thought a simple turtle capable of such a thing?!

Those things weren't really on my mind that day in the side-channel pool. I was, however, a bit confused as to why a mussel would be so difficult to pull out of the muck. How odd so much force would be required. I remember imagining briefly how unique and interesting this mussel must be! After one final pull my hand emerged from the goo...

....with my fingers curled around a bony reptilian face complete with razor sharp lips, two eyes and a snout.

A few admissions are in order.

First, there was shouting. I must admit that for the next few seconds the air was filled with loud yelping verbage as profane as ever a terrfied biologist might ever muster. I pulled my hand away from that mouth and leapt backward with a speed and alacrity I have seldom mustered before or since.

Second, to be entirely truthful, the wildlife of Central Illinois are farily benign. It's pretty hard to play the fearless naturalist when the most ferocious thing for miles and miles around is a white-tailed deer. However. If one were determined to be injured by wildlife in a stream in Illinois, grabbing a turtle by the face might be one of the more effective ways to accomplish that. "Man mauled by turtle" would have been an attention-getting headline in the News-Gazette to be sure.

One additional admission that is necessary here is that I am not entirely sure it was a softshell turtle I had grabbed. The snout was foreshortened and covered with mud and from the angle I held it and was thus of indeterminate length. The lip seemed heavy and there were fine lines running along it toward the mouth. I did go back to the spot were the turtle was buried and found the broad back of his shell by thrusting my foot down through the muck. It was smooth and quite large but somehow I wasn't really in the mood to dig it all up. I confess I've told this story before with the species in question having been a common snapping turtle.




I can't honestly say which it was.

I am quite sure, however, it wasn't a mussel.

Oh. And when the study ended two years into the plant's operation, we did find some evidence that it was causing some mussels to lose weight. Fortunately, the numbers and diversity of mussels (and fish) were unaffected. Hopefully someone will be keeping an eye on that over time. I'd be willing to help...

...but I might not sample the side-channel pool.

Summer tananger (Piranga rubra)

Only recently have I taken to carrying a camera with me around Belize. They're expensive and in some cases off-putting since they make you look like a tourist. It's also one of those dreaded "possessions that posses you". Over time it finally occurred to me how many astonishing things I was missing by trying to look cool and I decided the camera was coming with me regardless of how foolish I looked. Fortunately, a compact, shock resistant water proof camera has reduced the anxiety of bringing one along.

So now shots like this spring up all the time. On a simple walk to the store, I rounded a corner in the road and there this fellow sat, impossibly red and splashing around this filthy, but apparently functional, mud puddle. For a moment a yellow-headed warbler was also sitting there beside him but he flew away before I could frame the shot.

That's how Belize is. The diversity of animals there is just astonishing and you never know what is around the bend. I normally see twenty species of birds on a simple walk to the road. If you pay attention (and people who know me will attest that I do, much to the misfortune of my driving and conversational skills), you'll eventually see things you never imagined before. That does of course require a modicum of luck...

...and a few other things as well.

The summer tananger (or beebird) is a neotropical migrant. That means every year, for the few years it lives, it migrates from tropical places as far south as Boliva to open oak and hardwood forests of the United States. They're even found in the Midwestern US and Illinois where I currently live. Unfortunately, I've never seen one there (despite my wildlife viewing compulsions). The upshot of this bird's annual migration is that it requires suitable habitat in two different ecoregions, sometimes in two entirely different continents. What happens to them in the US affects their abundance in Belize and vice versa.

Presently, populations of the summer tananger appear to be stable. However, as their name implies, this species feeds on bees (and is actually a pest around apiaries). Honey bee populations in the US have crashed in the last year. Will the summer tananger find alterative prey while in the US and remain stable and unaffected?

Keep your eyes open and let's find out.

Goliath Grouper (Epinephelus itajara)

Biologist Eric Fernandez and I encountered this fish during a day of sampling in Placencia Lagoon. The man who had caught it was a Garifuna fisher from that village of Seine Bight. We found him happily paddling back home from drop fishing and checking set lines tied to the mangrove the night before. The hook from the set line was still in the grouper's mouth.

We paid the fisher to take a tissue sample from this fish. From the stable carbon isotopes in that sample, we found this fish was feeding from a foodweb based primarily on mangrove. In some senses, this fish was unique. Most of the fish we tested in the lagoon had used a much higher proportion of carbon from sea grass and single celled algae. Almost all the tissue in this fish came from animals that had been feeding on mangroves. I suspect crabs were its' primary prey.

The link between mangroves and goliath grouper is well established. Recently scientists have discovered that as juveniles, they live among the prop roots of red mangrove. Later, they migrate out to the Mesoamerican Reef where they can attain sizes well over 100kg. Fishers in Seine Bight have targeted Placencia Lagoon goliath groupers (formerly known as "jewfish") for generations. That fishery is still active and Seine Bight fishers still actively harvest goliath grouper in gill nets and with handlines.

Considered alone, the long standing goliath grouper fishery is probably not a threat to the sustainability of this species. Certainly some economic benefits arise from their harvest. The fish in the picture above represents a modest economic boon for the man who caught it (US 2$ per kg at approximately 10kg). However, coupled with the large scale changes that are occurring in coastal Belize, there are concerns about the conservation status of this species. After all, the fish in the picture above is still very much a baby. How many of those "smaller" fish are maturing to become adults and reproduce? When coupled with the wide spread removal of mangrove by developers, and the reduced water quality from effluent sources is there reason to be concerned about goliath groupers in Placencia Lagoon?

An additional concern is raised by a recent study by the Biodiversity Institute found that tissues in just over half goliath grouper they sampled in Southern Belize contained methyl-mercury levels above the USEPA threshold for health advisories. Children and pregnant women feeding on goliath grouper more frequently than twice a week are at risk are at risk for neurological damage.

http://www.briloon.org/pub/doc/posters/07Grouper.pdf

Some data from this study seems to indicate that the higher a goliath grouper feeds in the food chain, the more mercury it is likely to contain. Mercury increased with delta-15N levels in the tissues of this species. This pattern fits well with the observation that mercury bioaccumulates, or concentrates in the tissues of animals that feed on other animals. Delta-15N also tends to rise as fish feed higher in the food chain.

Because larger fish tend to consume larger prey that are often higher in the food chain than smaller prey, it is possible that consuming larger goliath groupers poses a greater health risk than smaller ones. These researchers will examine this and other questions over time.