USC Dana and David Dornsife College of Letters, Arts & Sciences > Blog

January 30, 2012

Marine Protected Areas- How Are They Enforced?

Filed under: Marine Protected Areas — admin @ 10:42 pm

Marine protected areas or MPA’s have become a major part of marine ecosystem management plans. According to Hamilton et al.’s 2009 paper in Sustainability Science, MPA’s have proven to have enormous conservation benefits in the areas where they have been implemented. After five years of protection in the Channel Islands Hamilton et al. found that there were significantly higher densities and biomass of targeted fish species inside the reserves compared with outside. In addition, Roberts et al. found that marine protected areas play a key role in supporting nearby fisheries. The evidence of these researchers reveals that MPA’a are an effective means of protecting ecosystems but what happens if people refuse to abide by the parameters of the MPA and if local governments can’t do anything about it?

On July 18th, 2011 an industrial fishing vessel from Ecuador, the Fer Mary 1, was caught with what turned out to be the biggest case of shark killing in the history of the Galapagos National Park. The Fer Mary 1 was detected by the Vessel Monitoring System (VMS) used by the Galapagos National Park Service (GNPS). The GNPS sent a crew to intercept the vessel operating 20 nautical miles inside the Galapagos’s Marine Reserve. They found 357 different species of shark, including one Mako, protected under the Convention on Migratory Species, and several species on the IUCN’s red list. All shark species are protected inside the reserve.  Despite the clear evidence the crew has not even been charged yet. According to Galapagos law, if the crew is convicted they could get up to 3 years in prison. They have not even been officially charged yet. An investigation was opened and the crew was detained but on August 3rd, 2011 they were released by the order of a judge. In order for the case to move forward all parties will have to return to the island, but history has shown that when asked to return the accused do not. Police do have the authority to detain them and transport them back but the budget to do so does not exist. In addition the court has declared itself “incompetent” in dealing with environmental crimes.

Lady Justice has Abandoned Galapagos

So hundreds of sharks were poached in a marine reserve and their function within the ecosystem will likely be disturbed. Yet, those who clearly violated the law faced no punishment because of the ineffectiveness of the local judiciary.

The enforcement mechanisms off our own coast have proven to be effective so far. In 2009, the Risa Lynn was given a $10,000 fine for illegally fishing in the Channel Islands National Marine Sanctuary south of Anacapa and Santa Cruz. It was a coordinated effort by the NOAA Office of Law Enforcement, the CA Department of Fish and Game and the U.S. Coast Guard. http://www.nmfs.noaa.gov/ole/news/news_SWD_081009.htm

Therefore, the probability of poaching and the effectiveness in deterring poachers with the strength of enforcement mechanisms should be considered to a greater extent when analyzing the effectiveness of a marine reserve.

In addition, (since marine protected areas around the world are very important parts of the greater ocean ecosystem and vital to the biodiversity of the planet) should we and do we have the responsibility to help protect areas like the Galapagos and other marine protected areas around the world?

This post was written by Evelyn Cintron, a senior (BA) majoring in Environmental Studies with a minor in Biological Natural Science.

January 26, 2012

Marine Protected Areas

Filed under: Catalina Island,Marine Protected Areas — admin @ 8:32 pm

Marine Protected Areas (MPAs) are government-protected regions in which human activity is regulated in order to preserve both marine resources and their unique ecosystems. Through different types of management programs and restriction strategies, government and local communities collaborate in order to protect threatened marine biodiversity and landscapes. Although MPAs may differ substantially in their size, location, and level of restriction, the majority of MPAs are established within territorial waters where enforcement can be ensured.

There are a variety of management approaches utilized by government in order to rehabilitate threated marine ecosystems.  The least prevalent—occurring in less than 1 percent of all United States’ waters—are “no-take” zones, areas where fishing is not allowed.  Other more common restrictions are ship transit regulated areas and areas of no oil and gas mining. “Seasonal and Temporary Management” restricts fishing seasonally in order to allow fish populations to recover from harvesting, common during the spawning season of over-extracted fish species.  Because MPAs are difficult to enforce, communities participate in their protection by managing and imposing restrictions, either independently or jointly with the government. Because they are aimed at addressing ecological and socio-economic needs, in return, they positively influence the communities supporting them.

MPAs are widely recognized as a successful method for not only preventing further marine habitat degradation, but also, for the recovery of targeted fish populations. By limiting access to protected areas, the stress placed on local marine populations— due to fishing and other industry—is substantially reduced. Thus, mortality rates are reduced, which results in the survival and establishment of targeted species’ populations. While perhaps the biomass increase of targeted species might be most noticeable within the boundaries of the MPA, another effect, the ‘spillover effect’, has been shown to boost fish stocks in the areas surrounding MPAs. When localized overpopulation of certain species within the MPA occurs, individuals within fish populations leave the MPA in search of a less competitive environment. This exodus provides a steady stock of fish for fishermen operating outside the MPA. Recent research indicates that the spillover effect also applies to larvae, which drifts with ocean currents to surrounding areas. As a result of this migration, MPAs are designed into networks, which are aimed at establishing fish populations over a large area.

Despite the weight of scientific evidence supporting the benefits of MPAs, certain stakeholders still criticize and oppose the establishment of additional MPAs. The local fishing industry frequently opposes the development of MPAs due to potential restrictions that may limit their access to profitable fishing grounds. This is a natural concern, particularly if local fishermen do not understand the potential benefits of MPAs—increased catches of fish and larger game fish due to the spill over effect.  Other major stakeholders, representatives of the shipping industry, argue that certain MPAs restrict the flow of commercial and other various types of shipping vessels, which in turn cost companies money. In addition, oil and gas officials, argue that restrictions prevent them from pursing untapped oil and gas reserves that exist within restricted areas. Finally, the establishment of MPAs might infringe on the rights of indigenous peoples to extract resources from protected areas.

In the beginning of the decade, Marine Protected Areas came to the forefront of many international assemblies.  In order to draw attention toward the issue, the World Summit on Sustainable Development (2002), The Evian Agreement (2003), and United Nations Framework Convention of Climate Change (2004) set goals of establishing marine networks by 2012.  Although these goals were criticized as vague and ultimately unenforceable, they highlighted the importance of MPAs in order to mitigate recent marine biodiversity loss on a global, regional, and national scale.  In effect, many nations, including the United States, pledged to establish them.

In 1999, California passed the Marine Life Protection Act.  A part of the California Fish and Game Code, the Marine Life Protection Act requires MPAs to be established into a network by 2011.  Designed by a team of public advisers—the Blue Ribbon Task Force, a group of 7 public policy leaders nominated by the California National Recourse Agency— stakeholders and scientific advisory groups, MPAs and networks are created based on scientific case studies and statistical analysis.  California’s statewide MPA network is divided into five regional networks—the north coast network, San Francisco Bay network, north central coast network, central coast network, and the south coast network— which are strategically linked together. Initiated in September of 2007 and projected to be completed in 2012, the California MPA network consists of more than 18% of California’s state marine waters. Within the Los Angeles County, a part of the south coast network, there are thirteen MPAs, with nine MPAs surrounding Catalina Island. Evaluated based on adequacy, representability, resilience, and connectivity, these MPAs are constantly being monitored and evaluated in order to improve and gain more information on trends of ecosystem rehabilitation.

Despite an increased awareness towards marine biodiversity and its habitat, there still exist many at-risk marine environments internationally.  Because international waters are nearly impossible to monitor and enforce, there remains a huge inconsistency between international and national efforts towards marine protection and rehabilitation.  With constantly changing marine ecosystems, due to over extraction, pollution and global warming, marine biodiversity and marine habitats are projected to only deteriorate further.  However, scientists and conservation workers are suggesting an international network of MPAs—a web of interconnecting “breeding grounds”, aimed at feeding biodiversity to fisheries and the marine ecosystem on an international scale.   Although this might not be politically feasible in the near future, scientific evidence indicates that if this feat can be accomplished, it would positively impact on both the marine environment and those individuals who are economically dependent on the ocean for their survival.

Additional References:

National Marine Protected Area Center.

NOAA’s National Ocean Service: Marine Protected Areas.

California Department of Fish & Game, Marine Life Protection Act.

Marine protected area.

This post was authored by Michalea McLoughlin, a senior Environmental Studies major (BA); and Nick Horsburgh, a senior double majoring in Environmental Studies (BA) and Psychology (BA)

January 23, 2012

Fires of the South Coast Bioregion and Our Efforts to Suppress Them

Filed under: Fire — admin @ 6:24 pm

The South Coast bioregion is comprised of a complex system of natural landscapes, climatic patterns, and ecological zones. This area includes the interior lands that line the Southern California bight. More specifically it is bordered by the Transverse Mountains, the US and Mexican border, the Peninsular Ranges and the Pacific Ocean. The Los Angeles Basin is located within these borders. The Transverse Ranges progress in an east to west trend, while the Peninsular Ranges progress north to south. This area, although making up only 8% of the land area of California, accounts for 56% of the state’s population (Keely et al.). In terms of the climate, the bioregion has a relatively mild climate, lacking in severe seasonality. The summers are hot and dry, while the winters are cooler and receive moderate amounts of precipitation. During the transition between summer and autumn, the area is hit with the strong Santa Ana winds. These winds can blow at extremely high speeds and account for much of the wildfire that spread is Southern California. The flora of the South Coast bioregion has been described as a mosaic. The aspects of this mosaic include grasslands, shrub land, woodland, and forests. These areas coexist within each other and fire regimes have very unclear boundaries. Because of this, the area can be divided into two larger ecological zones: the montane zone and the coastal valley/foothill zone.

Fires have been an aspect of the region as early back as 5-15 million years ago within the chaparral. Fossil charcoal records have been found within this area and support the claim that fires have been a key player since this time. How these fires have come about has changed drastically over time. Lightning strikes were the dominant ignition source in most parts of the region throughout the first half of the Holocene. The lightning strikes would not have created fire large enough to burn areas of the entire region, but if these localized fires were timed at a similar point in the year as the Santa Ana winds, the fires would be pushed by the winds and spread rapidly in the same way as we see in wildfires today. Fires started by lightning strikes were pretty rare during this time. It wasn’t until Native Americans and Spanish settlers reached this area of the United States that we saw a different ignition source pop up. As people began to settle the area they brought with them practices for agriculture, like burning shrublands for type conversion. This practice was common among many different kinds of people all over the region. These practices continued on into more recent times, but with more settlers came another change in vegetation. Spanish settlers spread nonnative grasses and forbs that competed with the natural fauna, and grazing became a threat to the land as well. Burning of the shrubland, especially in the areas where Los Angeles now sits, helped clear land for settlement and grazing of farm animals. It also paved the way for the extreme urbanization that is happening today and altering fire regimes even more than these beginning practices.

The Southern California area is home to an extremely dense population that requires further expansion into and development of untouched areas. With this population comes a higher risk for ignition of fires. A debate has risen over whether or not our fire suppression efforts in this area have helped or harmed the natural landscape. In a report done by the California Chaparral Institute, it noted that fire return intervals for chaparral was originally 30 to 150 years, but once humans settled in this area, the intervals have decreased dramatically, placing a great amount of stress on the chaparral. In his article “Reexamining Fire Suppression Impacts on Brushland Fire Regimes, Jon E. Keely examines the efforts of individuals to suppress fires by maintaining a young stand-age of fuels in the chaparral. It is believed that younger fuels will not burn as readily and limit the impact of fire. However, Keely goes on to show that fires are not stand-age dependent and will spread even with the younger fuels and the suppression efforts in their current form have not been successful.

Other individuals have believed that our suppression efforts have left an overabundance of vegetation that will help in the spreading of fires, but the California Chaparral Institute disputes this in their argument that while some forests have an overabundance of vegetation, the chaparral of California do not. They point out that instead of criticizing fire suppression efforts, we should value them for maintaining the damage fires could cause. It has been said many times that fire frequency and intensity in this area has increased, and the amount of potential damages is much higher than what it actually is (i.e. chaparral forests could have been completely converted to invasive weeds). This difference is due to the current fire suppression efforts. But as Keely brings up at the end of his article, more good could be done if we fine tune our efforts and focus not so much on the age of fuels, but more on creating a buffer zone between natural landscape and urban areas.

This post was written by Amelia Bahr, a senior Environmental Studies major (BA) with a minor in East Asian Languages and Cultures; and by Alex Anthony, a senior Environmental Studies major (BS).

Keely, Jon E. “South Coast Bioregion.” Fire in California’s Bioregions. 350-90. Print.

January 20, 2012

Fire in the South Coast Bioregion

Filed under: Fire — admin @ 12:04 am

Although wildfires are normally associated with the immediate destruction they also have necessary function and a place in many ecosystems. Some benefits from periodic wildfires include the removal of accumulated dead wood, which may have been building; this then gives plants requiring higher levels of sunlight the opportunity to flourish. This excess of land also gives animals a chance to forage or nest. In addition to its land clearing capabilities, fires can be the stimulant enabling some plants to distribute their seeds and provide conditions allowing seeds to germinate. For these reasons it is clear the misconception that fires are bad is false. When viewed on a larger scale of multiple years or decades it is obvious that fires are a natural component of an effectively functioning bioregion.

Wildfire occurrence in the south coast bioregion is endemic. The dry climate of the natural desert of Southern California is a perfect catalyst for naturally induced fires. The boundaries to this area are the Transverse mountain ranges, the US border with Mexico, the peninsular mountain ranges, and the Pacific Ocean (this area does include the channel islands) – North, south, east and west respectively.

Lightning is often a frequent source of ignition for wild fires. This is not, however, the case in the winter and early spring, when ocean winds delay the onset of fire season in the coastal regions. Additionally the colder and wetter climate of the region at this time of year moistens the organic life making it harder to ignite.

An important contributory factor affecting fire occurrence in the south coast bioregion is the Santa Ana winds. These winds force hot dry air toward the coast. Firstly, they are preferred conditions for a fire to start and secondly, they occur at a time in early autumn when the plant life is at its driest and most susceptible to fire. Fire will also spread more rapidly due to the dry climate and the dry Santa Ana winds if a fire outbreak should occur.

Both lightning storms and foehn winds such as the Santa Anas overlap briefly, accounting for naturally occurring fires. However, in modern times, wildfire ignition is predominantly associated with human activity, and as such the surrounding bioregion has been exposed to a disproportionate number of fires what is deemed natural.

Although fires can serve a biological function, excessive fire to the organics of southern California is damaging to the previously mentioned organics and thus puts unnecessary strain on the local bioregion. This raises a moral question as to how human involvement is putting a strain on the south coast bioregion due to accidental fire ignition.

In the Sidebar 15.1 section, Keeley compares the fire regimes of Southern California to Northern Baja California. In 1975 United States’ scientist Dodge believed the burning patters would be different between the chaparral and coniferous forests depending on the side US/Mexico border. They believed Mexico did not practice fire suppression outside of towns and that fires were actually encouraged. Dodge found the “lack of fire suppression, frequent burning of the shrublands, and over-gazing Baja California” (Keeley 361) suggested land use patterns were the same above and below the border (361).

In 1983, Minnich compared burning on both sides of the border between 1972 and 1980 and found that fires were larger on the US side of the border (361). Critics, however, dispel these findings because they are based on two reports of large fires north of the border, but written records of fires south of the border were not available. The historical aerial photographs Minnich used in their place did not suffice, according to Keeley (361). The conclusion is the smaller fires south of the border represent the natural fire regime, and that the larger fires in southern California are a result of human induced fire avoidance. The fuel for the fire thus accumulates immensely for years, and the resulting fires are huge (361). This conclusion too is criticized because with fire suppression, large fires in southern California have not increased. In terms of comparing conifer forests, scientists attribute differences in forest structure as the reason for the differences in fire frequency.

Fulé et. al, studied fire occurrences in Chihuahua, Mexico. They found the prevalence of fire control regimes led to more severe wildfires, thus surface fire should be used as a management too, thus contradicting Keeley’s argument against Minnich’s conclusion that fires increase in strength with the accumulation of fuel with human-induced fire prevention.

Keeley also asserts some scientists believe climate could play a more prominent role than fire management policies. However, Keeley demonstrates the three-degree difference in latitude shows only few differences in forest structure and species.

Forrest and Harding state:

“People and their activities are as much a part of the post-fire environment as are native plants and animals, and any approach that does not incorporate human resources and values as part of a mitigation strategy fails to appreciate the practical interface between humans and their environment.”

While Forrest and Harding’s statement may be anthropogenic and optimistic, there is an important point to apply to Keeley’s study. Forrest and Harding affirm Keeley’s statement that humans drastically affect their environment. Human stewardship of land will determine its ability to function in its natural state.

This post was written by Elise Fabbro, a double major in Political Science (BA) and Environmental Studies (BA) who is currently pursuing her MA in Environmental studies, and by Richard Charlesworth a senior in Environmental Studies (BA) with a minor in Architecture.

Works Cited

Forrest, Carol L, and Harding, Michael V. ”Erosion an sediment control: Preventing additional disasters after the Southern California fires. ” Journal of Soil and Water Conservation  49.6 (1994): 535.

Keeley, Jon E. “South Coast Bioregion.” Fire In California’s Bioregions. 350-91. Print. Peter Z Fulé, José Villanueva-Díaz, and Mauro Ramos-Gómez. ”Fire regime in a conservation reserve in Chihuahua, Mexico. ” Canadian Journal of Forest Research  35.2 (2005): 320-330.

January 13, 2012

Natural History of Catalina Island

Filed under: Catalina Island — admin @ 10:45 pm

The Channel Islands are a chain of eight islands in Southern California off the Santa Barbara Channel.  Santa Catalina Island – often referred to as just “Catalina” – is located roughly 20 miles directly opposite Torrance and Palos Verdes and is one of the larger islands in the Channel Island chain (76 sq. mi.).  Catalina exhibits a mild, sub-tropical climate year-round and is composed mainly of a quartz base.  The vegetation resembles that of a desert/ chaparral climate, and noteworthy landmarks include Echo Lake and Black Jack Mountain.

California Channel Islands, from Wikipedia

Catalina is an oceanic island that was formed by tectonic activity as opposed to being a continental island that separated from the mainland many years ago.  This marine history was proved by the presence of fossils from plankton skeleton called diatoms.  The material created by the presence of diatoms, called diatomite, is white and looks somewhat chalky.  Continental islands’ native species often evolved from ancestral species that occupied the land before it broke away from the mainland, but oceanic islands are populated by immigrating species.  Catalina Island is relatively close to the mainland, and the island’s biodiversity reflects this proximity.  This follows the theory that larger islands will have higher levels of biodiversity than smaller islands, and islands that are closer to the mainland will have higher levels of biodiversity than those that are far away.  Over time, animals have rafted, flew, and swam across the channel to the island to populate Catalina and the other islands.  Once there, many have evolved to adapt to their new habitats.

Geological records are not necessarily conclusive, but it is possible to estimate species’ introduction to the island via remains and chart their arrival and extinction.  Additionally, researchers have noticed that many plant and animal species closely resembled species on the mainland, but their physical appearances differ slightly.  When species are separated from the mainland, and competitors or predators are removed, different physical traits may be selected over features that proved successful previously.

There are varying theories regarding the means of transportation taken by founder species and the reasons that species have changed in physical appearance.  The Island Fox, a species on six of the eight Channel Islands, is thought to have been introduced thousands of years ago when Native Americans brought them over as domesticated pets.

Island Fox, Photo: L. Collins

Present day feral cats and dogs were also introduced as pets, but are now wild.  More recent introductions, such as the Bison, have persisted on Catalina and have adapted to island life by evolving into ‘dwarf bison.’  The origin of the bison on Catalina is a funny one. In the 1920s, fourteen bison were brought to Catalina for the filming of a movie. After the movie was finished, the crew left the bison on the Island and their population grew quickly, now amounting to almost 600 across the whole Island.

Bison on Catalina Island, Photo: L.Collins

The island fox also exhibits a similar case to the bison of dwarfism and appears smaller than the average mainland fox.  The quail and squirrel, on the other hand, have become larger, exhibiting signs of gigantism.  It has been proposed that some smaller animals were able to grow larger over generations due to the lack of stress presented by predators and competitors, while once-large animals became smaller because there were not sufficient resources to keep them well nourished.  In addition, due to differences in environment and competition, some shrubs undergo ‘arborescence,’ which leads them to look more like trees after many generations.  On Catalina, this is true of the Toyon and Island Scrub Oak.  Species that can only be found in one place or region are called ‘endemic species,’ and Catalina Island contains eight such plant species and eight animal species as well as eight species of invertebrates.  According to the Catalina Conservancy, which managed 88% of the island, two of the plant species are still under review regarding whether or not they are truly endemic. An interesting case study is that of the Island Ironwood trees.  Many island endemics are often grouped as subspecies of mainland plants, but the Island Ironwood is the only species that is actually differentiated on the genus level from the parent species.  The Santa Catalina Ironwood (Lyonothamnus floribundus, floribundus) differentiates from the Island Ironwood (Lyonothamnus floribundus, aspleniifolius) in that the Catalina Ironwoods have significantly longer and wider leaves.

This post was authored by Nina Gordon-Kirsch ’12 an Environmental Studies major (BS) with a minor in marketing; and Annie Guo ’12 an Environmental Studies major (BS) with a minor in International Relations.

For more information about Santa Catalina Island, feel free to visit the Catalina Island Conservancy’s website.

Endemic Species as a part of the Natural History of Santa Catalina Island

Filed under: Catalina Island — admin @ 10:34 pm

Santa Catalina Island, as well as the other Channel Islands, off the coast of California exhibits unique, or endemic, biodiversity that makes it a place of interest for study by scientists.  Due to its consistent isolation from the mainland, species that have colonized Santa Catalina Island have evolved into distinct counterparts to their mainland relatives making them endemic.  These species originally have come to the island by various means such as the deposition of seeds of mainland plant species by flying birds or the “rafting” of animals on vegetative debris washed out to sea from mainland floods.  However, these endemic species have been threatened more recently by invasive species that have been brought by human activity.  Mitigation efforts have had moderate success although many native species have already been lost.

One particular example of a species endemic to Santa Catalina Island is the Santa Catalina Ground Squirrel.  The Santa Catalina Ground Squirrel is differentiated from its mainland counterpart by being noticeably larger.  Biologists have characterized the larger size of the endemic species as ‘gigantism.’ Gigantism is a common evolutionary trait for smaller vertebrate and many plant species that colonize islands.  Due to the lack of competition and predators on islands in comparison to the mainland, it is hypothesized that these organisms are able to evolve into larger forms of their mainland counterparts.

The Santa Catalina Ground Squirrel is endemic only to Santa Catalina Island causing it to be an interesting species to study for biologists and biogeographers.  Schoenherr, Feldmeth, and Emerson in their book, Natural History of Islands of California, state that it is not currently known why the Santa Catalina Ground Squirrel has not colonized the other Channel Islands as many other species have done.  Rafting on vegetative debris from the mainland is one possible explanation for how the endemic squirrels arrived on Santa Catalina although it would seem just as likely that the Santa Catalina Ground Squirrel would over time have rafted to and colonized other Channel Islands.  Schoenherr, Feldmeth, and Emerson suggest that due to evidence of the squirrel in Native American stool deposits on the island that they may have been brought to Santa Catalina for food.  Again, it is not fully understood why Native Americans would not have brought the squirrels to other islands for this same purpose.  One hypothesis for their endemism to only Santa Catalina may be that the island has remained isolated by the sea from its neighbors. This is different than the Northern Channel Islands that conglomerated into one larger island in glacial periods when sea levels were much lower than they are today.  The land bridges formed between what are individual islands today would have allowed species from those islands to intermix and colonize the larger landmass that subsequently was broken up when sea levels rose again.

One species that underwent further evolutionary differentiation due to the isolation of individual populations on separated Northern Channel Islands is the Island Fox. The Island Fox is present on most of the Channel Islands, with the subspecies of the Santa Catalina Island Fox being specifically endemic to Santa Catalina Island. Notably, the Island Fox has differentiated more than any other island mammal. It is closely related, however, to the nearby mainland’s Gray Fox. The Santa Catalina Island Fox is much smaller than its mainland relative representing a common evolutionary trait for larger vertebrates that colonize islands called ‘Dwarfism.’  Large animals’ tendency to be smaller when isolated on an island is attributed to the limited supply of food on islands as opposed to the mainland. However, it is not completely certain that the Gray Fox is the Santa Catalina Island Fox’s most direct ancestor as there is some dispute about how the Island Fox arrived at Santa Catalina Island.

Based on mitochondrial evidence and other scientific indicators, it is estimated the Island Fox’s common ancestor arrived to the Northern Channel Islands 16,000 years ago.  How the fox arrived at the Channel Islands, and more specifically Santa Catalina Island, is not known for certain, but evidence has indicated several possible methods. The vicariant distribution hypothesis is supported by the close relation between the Island Fox to three small fox species of the Yucatan region of Mexico and in Guatemala. Vicariant distribution relies on plate tectonics and the concept of a “land raft.”  About 29 million years ago, the Pacific plate and the North American plate, which meet on the west coast of North America, changed in their interaction from a head-on convergence to sideways motion also known as a transform system. The Pacific plate carrying the Channel Islands traveled north, breaking from near Sonora, Mexico, and brought the islands’ inhabitants with them acting as a “land raft.” Some suggest that when the plates shifted and caused the formation of the Channel Islands, the foxes came with the land.  As mitochondrial evidence suggests a much more recent colonization by the fox, this hypothesis is not as well supported.  Others suggest that the foxes may have come to the Channel Islands when sea level was low enough to make rafting on vegetative debris from the mainland.  However, the more widely held belief is that Native Americans who may have used the foxes as pets brought the fox to the Northern Channel Islands and Santa Catalina around 16,000 years ago.

The Santa Catalina Island Fox and Ground Squirrel are among the endemic species that are threatened by exotic species brought more recently to the island in the last few centuries. As Spanish missionaries settled California in the late eighteenth century, many domesticated animals like pigs and goats were introduced to the Channel Islands.  Invasive species quickly disrupted the ecological balance of the islands by destroying vegetation and competing with the native island species. Invasive plants took up valuable nutrients, water, and space from native shrubs. Pigs and hogs, rooting in the ground for food, exposed large amounts topsoil that was soon eroded into the sea causing a loss of fertility in the soil.  Goats, being indiscriminant eaters, ate vegetation so close to the ground that it was unable to recover.

Another invasive species, bison, was introduced to Santa Catalina Island not by settlers but by moviemakers. In 1924, bison were introduced to the island for the filming of the movie The Vanishing American. While bison populations have caused harm by eating and trampling native grasses, bison populations are now limited and graze on mostly introduced grasses preserving the natural plants of Catalina.  Also, the bison do not eat the vegetation as close to the ground as goats allowing for the vegetation to recover to a greater degree.

However, the negative impacts of these invasive species and human activities has not been able to rid the Channel Islands, and particularly Santa Catalina Island, of its fascinating and rich natural history and biodiversity. While some hypotheses suggest that the Santa Catalina Fox and Ground Squirrel were brought to the island by humans and therefore may be considered invasive, they have undergone thousands of years of evolution to become distinct species. Mitigation, conservation, and preservation efforts have been put in place and have had success. The Endangered Species Act has protected many of the endemic species of the island for years. In 1975, 42,135 acres, or 86 percent, of Santa Catalina was given over to the Catalina Conservancy for protection and management.  In 1989, efforts to rid Santa Catalina Island of the Feral Hogs and goats began including shooting or trapping the animals from helicopters and creating a sadly unsuccessful goat adoption program on the mainland. Today, it is estimated that there are less than 1000 goats, 3000 pigs, and 500 bison on the island with the western side of the island almost totally free of the destructive animals.  Regardless, many species unique to Santa Catalina Island regrettably have become endangered, or gone extinct, as their habitats are destroyed or taken over by invasive plants and animals. While Santa Catalina and the other Channel Islands provide great places to study endemic species and evolution, they also provide opportunities to study the management of invasive species, and conservation and preservation efforts that informs the work of others around the world combating these global problems.

This post was written by Brian Rodysill ’12, who is pursuing a BA in Environmental Studies with a minor in Natural Sciences; and by Alice Hall-Partyka ’14 who is pursuing a double major in Environmental Studies (BA) and Global Health.