This figure shows the density of kelp in kelp forests around to islands before and after a large reduction of Sea Otter populations. Sea Otters prey on urchins which when unchecked will graze the kelp into near non existence be eating the anchors where the kelp are attached to the substrate. Explain how a loss of Otters might have affected the populations of the Steller's sea cow, a large mammalian herbivore that fed on kelp in these ecosystems.

Sea otters, Enhydra lutris, are predators of sea urchins, Strongylocentrotus franciscanus. Sea urchins, in turn, feed on kelp. A study was conducted to determine the effect that Enhydra lutris has on kelp biodiversity. To do so, three bays that have had sea otter populations for varying amounts of time were assessed. Two different types of kelp were studied: a perennial kelp, Laminaria groenlandia, and other annual kelps. The results are shown in the graph below. Additional studies have illustrated the importance of sea otter populations in kelp ecosystems. In the absence of sea otters, the ecosystem collapses. What role do sea otters serve in this ecosystem?   a) Keystone species b) Dominant species c) Competitive exclusion d) Obligate species

Use the passage to answer the question. Gupples and Predation Which of the following conclusions is the best interpretation of the data presented in the figure? This bar graph shows the nitrogen excretion rate for guppies as a function of predation. The orange bar indicates nitrogen excretion O A. Gupples from low-predation ponds reach larger body sizes and for gupples from high-predation ponds. The green bar indicates produce more nitrogen. nitrogen excretion for guppies from low-predation ponds. Guppies with larger body sizes excrete more nitrogen. B. Gupples from high-predation ponds produce less nitrogen to avoid 60 - being detected. C. Guppies from low-predation ponds digest food less efficiently, thus 40 producing more nitrogen. D. Gupples from high-predation ponds reach larger body sizes to avoid being eaten and digest food more efficiently, thus producing less nitrogen. Guppies from high- Gupples from low- ed Vie MacBook Air 000 20 888 F4 F10 F5 F2 @ $ % & * 2 3 4 5 6 7 8 9 { W…

The dams that have been built on most rivers (two-thirds of the world's rivers do not run free) often stabilize river flow by increasing flows below the dams during droughts and degreasing the amount of flooding during periods of high rainfall. Using the intermediate disturbance hypothesis , predict how stabilizing flows would affect the diversity of river organisms below reservoirs .