November 29, 2012 | 1
Getting a second term is pretty good, but getting your own fish is arguably pretty good too because Obamafish. Say it out loud, it’s great.
Five new species of colourful, freshwater fish called darters have been discovered in river drainages in eastern North America and named after four Presidents and a Vice. Darters are the smallest members of the perch family, and are named after their ability to zip around, under and into rocks and sediment on the beds of clean, fast-moving waterways.
Almost 200 darter species have so far been discovered, most of which live in the rivers and creeks of northern Alabama and eastern Tennessee. They are one of the most diverse groups of native North American fishes, and range from having healthy population numbers, such as the rainbow darter (Etheostoma caerelum) of Ohio, to being extremely rare, with some species sustained by a single waterway. Fewer than 50 diamond darters (Crystallaria cincotta) have been caught in the past 30 years, and their tiny, vulnerable population has been restricted to Elk River of West Virginia, while the Maryland darter (Etheostoma sellare), found in a particular creek in Harford County, Maryland, has been named one of the world’s rarest fish.
While conducting what would become the first comprehensive examination of breeding colour variation among populations of the common speckled darter (Etheostoma stigmaeum), a wide-ranging species that runs through Tennessee and Arkansas to Georgia and Louisiana, Steve Layman from Geosyntec Consultants in Georgia and Rick Mayden from the Department of Biology at Saint Louis University discovered that some of these populations were so different, they were actually separate species.
“We collected live breeding males (in the spring), photographed them, and took detailed colour notes throughout the range of E. stigmaeum and the other species in the subgenus (Doration),” says Layman. “What we found was those populations in the highland drainages of Tennessee, Kentucky and the Ozarks were quite different in colouration from the populations of E. stigmaeum from Gulf coastal drainages and the lower Mississippi River basin.”
Darter males are known for their brilliant colouring, especially during breeding season, which helps scientists to identify them. Some are jade green with yellow stripes, others are patterned all over with blues, reds, yellows and hints of purple. The speckled darter is particularly striking, with small, orange spots sprinkled over a light turquoise body, with thick turquoise stripes running vertically down the length of its body. Its first dorsal fin, which is the large fin that sits just higher than the middle of its back, is decorated with two turquoise bands flanking a large, bright orange band.
Layman and Mayden compared the colour of E. stigmaeum’s face and the distribution of orange spots on the soft dorsal fin, which sits behind the first dorsal fin, to fish in the various populations they studied to distinguish them as new species. The anal fin, which sits at the lower end of its underside, and the caudal fin (tail), revealed further disparities. Morphological features also came into play, as scale rows, fin rays and sensory pores were counted and the presence or absence of tiny teeth on the upper jaw called palatine teeth were noted.
The first of the new species to be described by the researchers in a paper to be published by the Bulletin of the Alabama Museum of Natural History is the spangled darter (Etheostoma obama), the males of which are resplendent in bright orange and iridescent blue spots, stripes and checks. Endemic to the Duck and Buffalo Rivers of the Tennessee River drainage, the males can grow up to 48 mm long, while the largest females reach just under 43 mm. Twenty-nine percent of the specimens observed had palatine teeth.
“We chose President Obama for his environmental leadership, particularly in the areas of clean energy and environmental protection, and because he is one of our first leaders to approach conservation and environmental protection from a more global vision,” says Layman regarding how he and Mayden chose its name.
This is the Cumberland darter (Etheostoma gore), found in the Cumberland River drainage below the Cumberland Falls in Kentucky. While it looks very similar to the spangled darter in its male breeding colours, the Cumberland darter is smaller – the largest males stretching just 42 mm and the largest females 41 mm. Plus its spot counts were more inconsistent, and its fins featured more dark grey and white colouring. Genetic analysis also suggests that no gene flow is occurring between it and the spangled darter.
“Vice President Gore’s environmental leadership throughout his public service, and after he left office, contributed significantly to our society pivoting from regional environmental protection to a more global perspective on human impacts to our environment (global climate change),” says Layman. “He also has a geographic tie to the new species from the Cumberland River – Nashville, where he is from, is located along the Cumberland River.”
The bluegrass darter (Etheostoma jimmycarter), named after the ‘Bluegrass State’ in which it was found, sports an even duskier colouring through all but its caudal fin, with a more solidly turquoise cheek. It was found in the Green River drainage of Kentucky and Tennessee, and the species spreads widely to the upper Barren and upper Green Rivers and the Rough River. It’s a relatively large species, the largest males growing to 49 mm long, and the largest females 46 mm.
“President Carter preserved lands for wilderness protection, established a natural energy policy (signed into law the Department of Energy), and since leaving office has made tremendous contributions globally through his humanitarian work,” says Layman.
Another small species in the bunch, the highland darter (Etheostoma teddyroosevelt) can grow up to 43 mm if male, and 41 mm if female. Its lower lip is distinctively grey, and 16% of the specimens observed had palatine teeth. It was named after its home in the ozark highlands in Arkansas.
“President Roosevelt will always be known for his legacy of preserving vast areas for national monuments, parks, forests, and refuges, setting a precedent that many other presidents would follow (not only these particular leaders),” says Layman.
And finally, here’s the beaded darter (Etheostoma clinton), whose males eschewed the more solemn grey and black trimmings of the former three species for a rich blue-green hue. The biggest this little fish can grow to is just over 34 mm, the males only ever so slightly larger than the females, and palatine teeth were found in 100% of the specimens observed. It is known only from the upper Caddo and upper Ouachita Rivers of Arkansas, and the researchers named it after the unique dark grey band that runs along its body through the line of turquoise blue blotches, suggesting a string of beads.
“President Clinton also preserved millions of acres of wilderness, enhanced environmental protection of national forests, and has a geographic tie to the new species from the Ouachita highlands in Arkansas,” says Layman. “We admire these American leaders for their vision, leadership, and commitment to conserving our natural resources and protecting the environment for future generations.”
According to Layman, a genetic survey of the different species indicated that each of them is travelling on a separate genetic pathway, and their geographic distributions and the patterns of species relationships can be used to test biogeographic theories explaining how the species ended up where they did.
“If different groups of fishes inhabiting the same rivers show congruent patterns of species relationships, then these patterns may suggest how historical changes in drainage patterns of rivers (dating to pre-Pleistocene glaciation) may have provided geographic isolation eventually leading to speciation,” he says. “Darters are especially informative in this regard, because many species are restricted to single river basins in separated highland regions (east and west of Mississippi River) having complex drainage histories that were never glaciated.”
While none of these newly identified species currently warrant protected status, there are many factors that could change their situation. According to Layman, the most common threats to these and other species of darters include habitat alteration and fragmentation from dams; sedimentation of clean stream bottoms from land-disturbing activities, agricultural runoff, and urbanisation; changes in hydrology associated with developed land uses; and water quality degradation from point and non-point sources. “There is currently no concern about the population numbers in the wild of these five new species,” he adds.
Hat-tip to the Tennessee Aquarium Conservation Institute blog.
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