Outbreaks of jellyfish are reported worldwide, yet the environmental factors that control the sizes of jellyfish populations are not well understood. The scyphomedusan Chrysaora quinquecirrha occurs in the mesohaline portion of Chesapeake Bay each summer. Population sizes of the medusae show dramatic annual variations that are correlated with salinity and temperature. We measured the total numbers of ephyrae and polyps produced by benthic polyps of C. quinquecirrha in laboratory experiments lasting 42 d, and found that temperature (15. 20, 25°C) was not a statistically significant factor at low salinities (5 to 20P:m); however, ephyra production increased significantly with increasing temperature at high salinities (20 to 35%). Conversely, each 5°C decrease in temperature delayed strobilation (ephyra production) by about 1 wk. Salinity significantly affected the numbers of ephyrae and polyps produced in all experiments. Ephyra and polyp production was lower at both low (
In response to the complex challenges of understanding and managing the effects of human activities on coastal ecosystems, the research establishment has produced a plethora of reports and implemented a bewildering array of government-sponsored research and monitoring programs that are not cost-effective on regional or national scales. Consequently, the gap between national needs and the capacity of the nation's research institutions to respond is growing rapidly, and environmental policies are ambiguous at a time when coastal habitats and living resources are being lost or degraded at accelerating rates. A case is made that a grassroots effort is needed to develop cost-effect programs that are responsive to both local needs and national priorities.
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