6 to 10 feet. This silting prevents attachment of many organisms on the 

 footing and also causes turbidity in the water which limits visibility 

 to an average of approximately 8 feet at the surface and 1 to 2 feet at 

 the bottom. 



The position of the island one-half mile off the coast also allows a 

 varied environment in respect to exposure to the open ocean waves and 

 currents. This in turn provides for an environment which has exposed zon- 

 ation, protected zonation, and stages in between, making possible a greater 

 diversity of life than is usually found in an area of this size. Nearly 

 all of the forms of life found on the offshore Channel Islands now exist 

 on and around Rincon Island. Of great importance in maintaining this diver- 

 sity of life is that the island is closed to the general public and thus 

 gives the various organisms an opportunity to grow and develop undisturbed. 



The seaward side of the island is particularly rich in life. A rather 

 extensive kelp bed has developed and the more than ipOO tetrapods have pro- 

 vided an optimum environment for the reproduction and rearing of numerous 

 organisms, especially many pelagic forms. The kelp bed on this part of 

 the island becomes quite luxuriant in the summers with both Egregia sp. 

 and Maorooystis sp. predominating. Mussel beds several feet thick have 

 developed on the tetrapods with the myriad populations of organisms which 

 are associated with these beds. The primary fish forms that are resident 

 in this section are the perches and blennies. This is also the primary 

 roosting ground for the marine birds where temporary populations of several 

 hundred brown pelicans, cormorants, and gulls are regularly observed. 



The landward side of the island, while not as open to the general ocean 

 waves and currents but rather in the "backwash" or eddies that come around 

 the island, has a larger amount of life than might be expected in an area 

 with high water turbidity. Small kelp beds develop here in the summer 

 months and the great number of small fish found here testify to the value 

 of an area protected from the assaults of the open ocean on these small 

 developing forms . 



The other two sides provide an intermediate environment and each, 

 because of the difference in exposure to the prevailing currents and waves, 

 has a somewhat different ecology. The north side of the island has a 

 great variety of marine algae near the surface and contains the largest 

 gorgonian coral formations around the island. One of these, primarily 

 composed of Muricea sp., is over 50 feet long by 20 feet wide. The side 

 of the island with the more southerly exposure has the least amount of 

 algal growth, but the large population of sea urchins may be a contributing 

 factor to this lack of foliate algae. Gastropods are the predominant form 

 of invertebrate life on this side. A fairly well-developed and varied 

 bivalve population is also present. 



The three seaward sides of the island have a "talus slope" of mussel 

 and bivalve shells which in some areas extends 15 feet above the toe of 

 the rock slope. This formation is important in helping to keep down the 

 sediments and in providing small shelter areas for nudibranchs , gobies. 



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