Freshwater Fish Communities

by:

Jonathan Carpenter

Fishes are important commercial and recreational resources around the world, and Louisiana, the “sportsman's paradise,” is certainly no exception. I constantly see pictures of recreational anglers proudly displaying their catch – a bass, or a perch, or maybe a catfish, and although these fish are both important and interesting, what about the rest of the fish species out there? The United States and Canada support a staggering 790 species, at least 156 of which can be found in Louisiana. Most of the species are small, somewhat difficult to identify at first glance, and by most peoples standards inedible. These attributes, among others, have led to many species being lumped into a group collectively referred to as “bait fish”. Despite this generalization, these species perform a wide variety of important roles in our aquatic ecosystems. The natural history of each species, big or small, game or non-game, is closely linked to the natural histories of all fishes in its community. Even though small, common stream fishes like cherryfin shiners (Lythrurus roseipinnis) and pirate perch (Aphredoderus sayanus) are not often observed by anglers, they are integral parts of a healthy fish community and contribute to the functioning of streams throughout the state.

The region known locally as the Florida parishes in south-eastern Louisiana is characterized by a community of organisms that is different in composition from the communities in the rest of the state. The streams running through the area run clear if the weather hasn’t contributed too much recent rain, and their banks are often lined with native shrubs like illicium (Illicium floridanum) and azalea (Rhododendron canescens). The fish communities in these streams reflect these unique habitats, and include many difficult to observe species like southern brook lamprey (Ichthyomyzon gagei), shadow bass (Ambloplites ariommus), and an array of different darters (family: Percidae).

            The fish communities of these creeks are of great interest to LSU graduate student Brian Ward, a native of Charlotte, North Carolina with a B.S. degree in biology from Stetson University. He came to LSU in August of 2006 to investigate the relative importance of habitat and human land use activities on fish community composition. His methods are shocking – literally. Many of the species he is investigating are reclusive and regularly take shelter under overhangs or woody debris, making it impossible to catch them by typical methods like netting. Instead, Brian uses electricity. He wears a large, plastic encased pack (somewhat reminiscent of the packs used by the “Ghost Busters”) on his back, which is hooked up to a long pole. The end of the pole is held in the water, emitting a charge of about 700 volts or so. The charge does not kill the fish, but stuns them, and because most of these fishes have a gas bladder to keep them neutrally buoyant in the water column, they usually float to the surface once they have been stunned. The fish are quickly collected with dip nets and moved to a bucket to await processing. After they are measured and their identity is recorded, most are released back into the stream, although some are taken back to the lab for further study.  Brian will to use the data he collects to determine the factors that most strongly influence fish community composition in these streams, which may eventually lead to improved land use practices (particularly in the riparian zone near the stream) that help protect the integrity and biodiversity in Louisiana’s stream systems.

            Brian has a long-founded interest in fishes, and has traveled to the Caribbean many times to dive and observe the lives of reef dwelling species. After receiving his M.S. degree from LSU, he plans on continuing his passion for fishes in a career with a state or federal natural resource agency.

Sand Running Sparrows

by:

Jonathan Carpenter

For eight years, , RNR professor Phil Stouffer and his students have been involved in research on one of America’s fastest declining birds, the Henslow’s Sparrow (Ammodramus henslowii), a small, elusive grassland bird with a streaked back, rufous-edged wings, and a distinctive green face. The reason for the sparrow’s decline is complicated, and many researchers have been working to understand what can be done to keep it from following the same path as the passenger pigeon and the Carolina parakeet, two species of birds that have become extinct in recent American history.

The Henslow’s Sparrow is a member of the southern pine savanna community, a community heavily regulated by fire. In fact, this sparrow has a definite preference for habitat that has been burned within the last four years. Shrubby holly species typically begin to dominate patches of habitat that have not burned for some time. The lack of fire affects other aspects of the botanical community as well. As the native grass community changes, preferred food species, like toothache grass (Ctenium), are out competed by less preferred grass species. Also, without the short, fast fires coming through, natural litter builds up at ground level. This build up affects the foraging efficiency of Henslow’s sparrows, covering up many available seeds, and making their foraging pathways impassable. After four years without burning, they typically move out of the area, presumably to areas that better fit their habitat requirements.

            Henslow’s Sparrows are often difficult to observe in their natural habitat during the winter. They do have a call that is distinctive to the ear of trained naturalists, but they don’t seem to call as often as many other birds. Also, instead of flushing when they are approached, they typically just run along the ground. This habit is found in other sparrow species from the genus Ammodramus, which fittingly translates into “sand runner”. As one could imagine, their affinity for the ground makes the Henslow’s sparrow quite difficult to study in their tall grass, often boggy wintering grounds. There is, however, a method to the madness. A team of four to eight people spread out about ten or so feet from each other. Everyone in the group has some job to do, from just carrying the net, to keeping a compass bearing, to entering GPS points. The group moves across the habitat as a human wall. This method works so well because the ground-loving Henslow’s sparrow has no choice but to flush from the approaching wall. Once a bird is spotted, the group runs toward the area where it landed, which is usually in a shrub or some other woody vegetation. Now the group must act fast, before the bird either flushes again or decides to hit the ground running. Two people set up the net on one side of the bird, while the rest of the group encircles it. When everyone is in their positions, they all run toward the net, crashing and clapping in an attempt to get the sparrow to fly away from them and into the net. Now that the bird has been caught, if it has been caught, the sparrow is banded and the appropriate data recorded. Finally, the bird is released, and the whole process starts again until the entire plot has been surveyed. Sometimes, it takes many tries to catch one bird.

LSU has had many graduate students investigating different aspects of Henslow’s Sparrow ecology over the past eight years. Currently, the project has fallen into the hands of Matt Brooks. Matt grew up in Highpoint, North Carolina, and received his bachelors degree from University of North Carolina at Asheville. After getting his degree, he traveled far and wide, working with birds in exotic places like Hawaii, Ecuador and Peru. He came to LSU in 2006, and has just finished the first field season of his graduate research. His study plots are in DeSoto National Forest in southern Mississippi, though he also works in some of the long-term study areas that LSU has maintained over the last eight years. These long-term sites are in the Florida parishes of southeastern Louisiana. Along with Matt’s passion for birds, he also has a deep passion for plants. He is now using his passions and interests in these two subjects in an attempt to unravel aspects of the relationship between Henslow’s sparrows and the botanical community where they live.

Picture taken by Matt Brooks