Map of Catalina Island

http://www.best-beaches.com/us/california/southern-california/catalina-island

Image of Ecosystem

Present

Historic

www.catalinaconservancy.org

Historical State of Catalina Island

Millions of years ago, volcanic activity 26 miles off the coast of Southern California created the island of Catalina. Erosion and weathering processes eventually created Catlina’s terrain of rugged mountains and shallow soil. Characterized by a dry climate like the mainland of California, Catalina has little precipitation and relatively warm weather year round. Due to its distance from the mainland, the island initially lacked terrestrial life and was difficult for species to migrate to. Eventually species arrived via wind or drifting across the Pacific and formed an ecosystem with a wide variety of endemic species unique to Catlina island. The isolating nature of an island ecosystem makes endemic species common as they evolve in seclusion from their mainland counterparts. Prior to human disruption, Catalina was an ecosystem with a great diversity of endemic plant and animal species adapted to an isolated environment virtually free of competition and predators.

All information from Catalina Island Conservancy, Catalina Ecology

Human Impacts on Ecosystem

Catalina Island is the most populated of all the Channel Islands and population has gradually increased over the last hundred years, leading to a number of problems for the island’s fragile ecosystem. Invasive plants and animals have become a significant threat to native population. As humans migrated to the island, they brought many garden and landscaping plants like flax-leaved broom, genista, and fennal, which easily outcompete native plant populations. Non-native species make up 36% of the island’s flora, and currently, 76 invasive plant species are in need of control or eradication (Knapp, Oak Ecosystem Restoration pg. 35). Rare and endemic plants have suffered the consequence of this invasion, and many endemic plants have become rare and endangered including but not limited to Catalina ironwood, Catalina Island mountain mahogany, St. Catherine’s lace, and Catalina Manzanita (Catalina Island Conservancy, Rare and Endangered Plants). There are 6 federally listed threatened or endangered plant and animals species, 4 of which have been identified as being threatened with extinction by invasive plants. The island oak populations have been especially threatened by invasive species which increase fire frequency; affect oak ecosystem food webs; alter vegetation structure and composition; and compete for resources such as water, sunlight, and nutrients (Knapp, Invasive Plant Management Program pg. 36). Humans also brought animals to the island that the ecosystem is not adapted to support. These animals outcompete native animals for resources and also destroy much of the native plant life. One such example is bison, which were brought to the island in 1924 to film a movie and left on the island thereafter. The bison population exploded on an island ill-adapted for large ungulate animals, reaching 600 at its peak. Additionally, bison have exacerbated the invasive plant problem by spreading their seeds through their hair (Bison Study Executive Study). Native animal species have also suffered as a result of human activity. The Catalina Island Fox was declared critically endangered in 2004 after a population crash in 1999 caused by an outbreak of distemper most likely brought to the island by someone’s pet. The population once totaling at 1300 plummeted to the brink of extinction in a matter of years (Shahagun).
Terrestrial life is not all to have paid the price of human activity; water pollution has dramatically increased on the island within the last few decades. Avalon Beach Harbor has consistently ranked as one of the most polluted in the state within the last decade. On a national scale, the harbor has been declared one of the most chronically polluted beaches in the nation for failing state health tests 73% of the time (Barboza). The cause of such severe water pollution has been traced to the island’s outdated sewer system made of clay and metal pipes that are a century old (Barboza). The water leaches from these decrepit pipes into the groundwater and eventually into the bay. Marine habitats around the island have also suffered as a result of such sever water pollution.

Future Prospects and Improvement (what can be done?)

Future Prospects for Ecosystem

Catalina Island is aggressive in its attempts to limit human impact and has developed a number of programs and policies to help the island return to its original state.  The Catalina Island Conservancy, which owns 88% of the island’s land, works to balance conservation efforts and island recreation (Catalina Island Conservancy). The Conservancy has been effective at reducing populations of nonnative animal species, virtually eliminating feral goat and pig populations as well as controlling bison populations. Reducing these animal populations has proven to be somewhat of a double-edged sword, since the reduction of these animal populations has removed an important threat to native plant populations but also invasive plant populations (Bison Study Executive Summary). Partly to address this problem, the Conservancy developed CHIRP (Catalina Habitat Improvement and Restoration Program), which has established four strategies to control invasive plant populations and include 1) Species based 2) Site-based 3) Control along roads and trails 4) Prevention of new invasions (Knapp, Invasive Plant Management Program 37). They also have created a native plant nursery to restore these threatened populations (Catalina Island Conservancy, Native Plant Nursery). The Catalina Island Fox Recovery Plan has been yet another success for the conservancy, and has brought the fox population from the brink of extinction to just over 1,000 in 2010 (Sahagun). Given the island’s aggressive programs to control invasive species populations and restore native populations, future prospects in this regard look good. However, the island’s water pollution problem paints a less optimistic picture. The island has spent $3.5 million in testing and rehabilitating sewer lines with no improvement to water quality(Barboza). The outcome looks bleak for Avalon’s water pollution problem given the costs associated with fixing the island’s sewer system. 

Improvement: What Can Be Done?

Continued restoration efforts of native species will help native plants and animals return to a healthy state. The conservancy’s simultaneous efforts to control invasive plant and animal populations will gradually bring the island to more closely resemble its historic, original state. A major priority for the island should be replacing the sewage system in its entirety, since it is considered the only solution to the water pollution problem. Additionally controlling the effects of human recreation on the island, i.e. by closely regulating camping and boating; diving; and tourism, will give the natural habit a chance to restore itself. 

Data

Island Oak Population 

The graph above shows the hectares of oak lost for each timeframe. 

The image above shows the decrease in oak distribution by year. 

          www.catalinaconservancy.org

Bison population (Bison Study Executive Summary)

            1924: 14 bison

            1960: 600 bison

            Present: 150 bison

Fox population (Shahagun)

            Pre-population crash: 1,300 foxes

            1999: 100 foxes

            2008: 784 foxes

Water pollution (Barboza)

Has spent $3.5 million testing and rehabilitating sewer lines but the water is no cleaner

Avalon Beach Harbor fails state health tests 73% of the time