Roger Newell proposed that removal of most of the oysters that were once so abundant in the Bay also may leave much uneaten plant material suspended in the water to be consumed by copepods, which in turn could be used by jellyfish and increase their populations. Unfortunately, no early records document the abundance of the Sea Nettle before Man began to seriously change Chesapeake Bay, so there is little with which to compare the present abundance.
David Cargo kept daily records of the numbers of sea nettles at the Chesapeake Biological Laboratory in Solomons, MD for nearly 30 years. He found great annual variation in jellyfish numbers: more occurred in dry years than in rainy years, but no overall increase in abundance was apparent. Such records would need to go back more than years to reveal if human-caused changes in the Bay have affected the abundance of sea nettles.
A lot of effort was spent on jellyfish control in the s, but no method has been very successful.
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Nets and bubble screens were used to keep them away from swimming areas. The jellyfish tended to clog the nets and to break into pieces that continued to sting. The bottom-living polyp stage also was targeted. Chemicals that killed the polyps also killed many other organisms, and so were unsuitable. A small species of sea slug was found that ate the polyps, but culture methods to produce large numbers of the sea slugs were unsuccessful, and they did not live well at the low salinities favored by the polyps. So far, the greatest reduction of the jellyfish populations occurred after Hurricane Agnes in , but this method of control cannot be recommended.
Research in my laboratory has shown that sea nettles may help oysters. Oysters have a larval stage that spends about two weeks swimming in the Bay before they settle to grow into large oysters. During this swimming stage, they are vulnerable to predators such as sea nettles and comb jellies.
RSPCA Biodiversity KS3 Lesson Plan – Predator/Prey Relationships and Human Activity
Although sea nettles can catch the larval oysters, they spit them out undigested and unharmed. In contrast, comb jellies catch and digest the larvae readily. Comb jellies are a favorite food of sea nettles, and they reduce comb jelly populations to zero in the tributaries during the summer when oyster larvae are most abundant. Therefore, sea nettles appear to protect oyster larvae from a major predator. In my laboratory, we have been working to determine the importance of sea nettles as predators of copepods.
This is of interest because if sea nettles reduce copepod populations, then less food would be available for planktivorous fish, for example bay anchovy and menhaden, which then are food for piscivorous fish like striped bass and bluefish. This research was in collaboration with Dr. Ed Houde of the Chesapeake Biological Laboratory.
We also are studying which environmental factors have the greatest effects on the population size of sea nettles. We have done experiments to measure the numbers of sea nettles produced by polyps, and the survival and growth of the baby jellyfish at various comblnatlons of salinity, temperature, and food concentrations. I am beginning a large-scale project to map the distributions of jellies throughout Chesapeake Bay in April, July, and October.
In collaboration with several other scientists, I will examine environmental and biological e.
Contact Us. Students will define ecological forecasting, and be able to describe three examples of this process. Students will explain how the life cycle and ecological preferences of sea nettles help make them unusually abundant in the Chesapeake Bay. Students will describe the economic and ecological impacts associated with large numbers of sea nettles in the Chesapeake Bay, and how ecological forecasting may help reduce these impacts.
Purcell found at the end of this lesson plan. Click here for a printable copy of the student worksheet. Click here for a printable copy of Appendix A. Provide information needed to make effective decisions about how best to maintain benefits from coastal ecosystems such as whether or not to prohibit harvest of certain species during reproductive seasons or limiting the number of certain species that can be harvested by humans ; Reduce the negative impacts from extreme natural events and human activities for example, by protecting wetlands from development to maintain the ability of these systems to buffer the effects of severe storms or floods ; Apply scientific knowledge and technical capabilities to improve the use of coastal resources; and Identify ways that scientific research and monitoring can contribute to more accurate ecological forecasts.
Purcell , one copy for each student or student group. Complete Part II as a class exercise; or Walk through the steps before students begin this part of the lesson; or Allow students to work through these steps on their own. Interdependence of organisms Behavior of organisms. Personal and community health Population growth Natural resources Environmental quality Natural and human-induced hazards Science and technology in local, national, and global challenges.
Fundamental Concept g. The ocean is connected to major lakes, watersheds and waterways because all major watersheds on Earth drain to the ocean. Rivers and streams transport nutrients, salts, sediments and pollutants from watersheds to estuaries and to the ocean. Fundamental Concept h. Although the ocean is large, it is finite and resources are limited. Fundamental Concept d. Ocean biology provides many unique examples of life cycles, adaptations and important relationships among organisms such as symbiosis, predator-prey dynamics and energy transfer that do not occur on land.
Fundamental Concept f. Ocean habitats are defined by environmental factors. Due to interactions of abiotic factors such as salinity, temperature, oxygen, pH, light, nutrients, pressure, substrate and circulation, ocean life is not evenly distributed temporally or spatially, i. Some regions of the ocean support more diverse and abundant life than anywhere on Earth, while much of the ocean is considered a desert.
Fundamental Concept e. Humans affect the ocean in a variety of ways. Laws, regulations and resource management affect what is taken out and put into the ocean. They wait a day or two after each egg before laying the next. The first chick to hatch is bigger than the others and may actually kill it's younger siblings if food is scarce.
I'm sure all of us oldest children have envied the raptors once or twice in our lifetimes. The length of time it takes for the babies to get large enough to start flying is called the "fledgling period". This can be anywhere between 20 and days. This is a big part of the raptor parents' life! Especially since they lay eggs every year.
Falconiformes are "diurnal" which means they hunt mainly during the day -- for example, eagles, hawks and falcons.
Stringiformes is just a fancy way of saying owls. This order includes two "families" -- the Tytonidae barn owls and the Strigidae all other owls.
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Study Pack. Chapter Summaries. Free Quiz. Topics for Discussion. Download the Study Pack. Lesson Plan. Eyes of Prey Lesson Plans contain pages of teaching material, including:. Eyes of Prey Lesson Plans Introduction.