Gene transfer technique has allowed the relocation of genes from one organism to another to create new line of organisms with improvement in traits important to humans. Genetically modified organisms (GMOs), therefore, hold promise for producing genetic advances, such as rapid growth rate and yield of crops and herds, increased production and effectiveness, disease resistance and broad ecological ranges (Whitman 2000). The latent economic benefits of transgenic technology to us are obvious. Transgenic organisms production has the goal of producing food and medications for human utilization; thus the design of genetic constructs must take into consideration the potential risks to consumer health, as well as the possible hazards to the environment (Levi 2000). Risks can be characterized by several parameters. A risk is commonly defined to be the product of the extent of damage and the probability of its occurrence. But there are several other characteristics to be taken into account: degree of certainty in determining extent and probability, persistency, ubiquity, irreversibility, delay effect and mobilisation potential. As potential risks of genetically modified plants (GMPs), resistance to antibiotics, impact on non-target organisms, spread of genes and GMOs, and secondary consequences, e.g. on cultivation practice (Steinhaeuser 2001).The ecosystems are too complex, and our understanding of them too fragmentary. In addition, presently available techniques to supervise short and long-term ecological consequences of GMO release are absent or unreliable. Lastly, the socio-economic and biodiversity aspects of GMO usage are unclear, and often unpredictable, based on the present state of knowledge. Hence, applying the precautionary principle should be an important basis for initiation of risk-associated research as well as for elaboration of more satisfactory risk assessment methods and procedures(Myhr 1999).
Coral reefs are among the most diverse and beautiful communities on Earth, home to over twenty five percent of all marine life. Coral reef communities are found in warm and tropical oceans worldwide, and have come to boast some of the most remarkable examples of predator-prey interactions (Arnal & Cote 1997). Predator-prey relationships have been studied extensively, and it has been found that it is a major ecological force structuring the composition of coral reef fish communities (Sancho 2000).
Predation plays an important role in the assemblages of coral reef fishes. Reef-fish communities are often teeming with piscivores, and this becomes a limiting factor in the recruitment and post-settlement survivorship of many prey species (Caley 1993). Predation potential is the propensity of the predator to consume the prey, integrating such factors as abundance of predators, prey-species composition, the feeding preferences of the predator and the availability of alternative food sources (Aronson 1998).
Analyzing the predation potential is important when trying to discern the effects of piscivorous fish within coral reef communities. The general predation hypothesis states that in the absence of predator, prey-fish densities will increase. It also asserts, reciprocally, that in the presence of intense predation, local prey species richness will decline (Danilowicz & Sale 1999). The predation hypothesis also incorporates the theory that predator strategies for capturing of prey and prey defenses are all stabilizing factors in the scheme of predator-prey interactions.
Literature Cited
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2. Wulff JL (1997) Parrot-fish predation on cryptic sponges of Caribbean coral reefs. Marine Biology 129: 41-52.
3. Danilowicz SS, Sale PF (1999) Relative intensity and predation on the French grunt, Haemulon flavolineatum, during diurnal, dusk, and nocturnal periods on a coral reef. Marine Biology 133: 337-343.
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