SEA GRANT NEWS & NOTES AROUND THE NATION - JANUARY 14, 1998
WILD RICE FLOWERS COULD HOLD CLUE TO PLANT'S DECLINE
A decline in Minnesota's wild rice population has researchers and harvesters puzzled. The situation is so severe that some strands have been totally lost. Minnesota Sea Grant researcher Qinqin Liu suspects one clue may lie in the sexual development of the rice flower.
Part of the problem lies in its genetic complexity. Wild rice has twice the DNA and three more chromosomes than white rice. It is also highly attuned to environmental changes. Liu suspects that genetics and factors such as water quality and quantity, plant density, available nutrients, and hormones could cause the flowers to actually switch their sex during development.
To determine this, Liu and her colleagues analyzed the sexual characteristics of cultivated wild rice populations using an electron microscope and computer imaging. They found that, like corn and other plants, wild rice plants start out with both male and female organs in the same flower, and then undergo changes to form unisexual flowers. But, unlike the other plants, some wild rice flowers found in the "transition zone" -- the part of the stem where the male and female flowers meet -- remain hermaphroditic (male and female combined). This suggests that cell death or reduction may be more prevalent in these flowers.
Liu is hopeful that her research will determine what factors have the most influence on the sexual development of the flowers and how this affects rice production and survival. Eventually, it could lead to conservation of wild rice seed sources and improved management of rice beds. "As long as we have aquatic environments, there will be rice," Liu said. "We need to better understand how to manage it. If we know what signals that a rice stand is in trouble, we might be able to restore populations before they disappear."
CONTACT: Qinqin Liu, Minnesota Sea Grant Researcher, (O) 218-726-7271; E-Mail: [email protected]
FUNCTION FOLLOWS FORM? DESIGN KEY TO SUCCESSFUL REEF FLAT RECOVERY
Reef flats are located in shallow areas between the shoreline and the outer growing area of coral reefs. In the Pacific islands, these largely barren areas, made up mostly of fossil coral material, are dredged and their substrate used for construction materials. Hawaii Sea Grant researcher Paul Jokiel is investigating the characteristics of reef flats and collecting environmental and physical data that will help in determining the most productive way to dredge.
He hypothesizes that if a reef flat quarry is designed with complex topography and good flushing, it can be colonized by coral and fish, creating a useful reef environment. "When these quarries are dug, the materials are removed, creating a big hole in the shallow reef flat," Jokiel said. "That big, deep hole can become a very lush reef or it can become a sediment-filled hole with nothing in it. We are not advocating the excavation of pits. What we are saying is that if it is necessary to do, you might as well do it in a way that produces a potentially very productive environment when you are through."
Jokiel will be studying abandoned reef quarries in Pago Pago, American Samoa where dredging has occurred for several years. By analyzing the design of different quarries, he will attempt to determine what conditions most favor development of a healthy reef community following the completion of dredging.
"After the job is done, in the best situation, there will be a lot of coral after five years and in 10 years you will definitely be impressed with the amount of coral and the numbers of fish," he said. Ultimately, Jokiel hopes to produce a set of guidelines describing the positive design of reef flat quarries that can be made available to regulatory agencies and governments throughout the Pacific.
CONTACT: Paul Jokiel, Hawaii Sea Grant Researcher, (O) 808-236-7440; E-Mail: [email protected]
MANAGING DISEASE IN FARMED FISH: RESEARCHERS STUDY ALTERNATIVE TO ANTIBIOTICS
Successful, consistent and reliable production of aquacultured fish depends upon the control and prevention of disease.
Maine/New Hampshire Sea Grant researcher Steve Jones and George Nardi, co-owner of Great Bay Aquafarms are taking a different approach to bacteria management. The team is identifying good and bad bacteria living in the gut of aquacultured larval summer flounder. This strategy, called probiotics, aims to manage disease through an understanding of the microbial ecology of fish.
"You need to study organisms to see what bacteria are associated with the way that you're growing them," said Jones, an associate professor at the University of New Hampshire. He and Nardi hope that through their studies they will be able to establish large populations of beneficial bacteria and manage bacteria that are potential threats. "If we know which [bacteria] are pathogenic," Jones said, "we can monitor and time preventative measures."
Jones and Nardi are compiling a database of microorganisms and relating what they find to incidences of higher mortality. The goal, said Jones, "is to enhance the health and disease resistance of fish through manipulation of benign and beneficial microorganisms." The process may be an alternative to antibiotic treatments which, over time, can result in more resistant strains of bacteria.
CONTACT: Steve Jones, Maine/New Hampshire Sea Grant Researcher, (O)603-862-2175; E-Mail: [email protected]
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