Western Transverse Ranges-Channel Island Block
More than 20 million years ago the Farallon plate divided the North American and Pacific Plates. After the Farallon Plate subducted beneath the North American Plate, the Pacific Plate collided with the North American Plate creating a boundary line known as the San Andreas Plate Boundary, or more commonly referred to as the San Andreas Fault. Along the San Andreas Fault, the Pacific Plate moves in a northwest direction in relation to the North American Plate moving in a west southwest direction, creating the now present transverse plate boundary. As the two plates move alongside one another, small blocks of continental crust occasionally break free from the plates. In this case, the Pacific Plate pulls and collects pieces off the North American Plate northward.
Two of the crustal blocks that have broken free from the North American plate due to the friction between the two plates are the Western Transverse Ranges-Channel Islands Block and the Baja California Block. As the Pacific Plate moves in its northwest direction, it has locked onto the southern end of the Western Transverse Ranges-Channel Islands Block that was once situated near San Diego and pulled it northwest while the northern end of the crustal block remained relatively stationary near the Mojave Desert, causing the Transverse Mountain Ranges to pivot clockwise 100 degrees from its original north-south orientation to its now east-west orientation. The Western Transverse Ranges-Channel Islands Block contains the mountains north of Los Angeles, this includes the San Bernardino Mountains, San Gabriel Mountains, Santa Ynez Mountains, Santa Monica Mountains and the four northern Channel Islands, which are actually the western extension of the Santa Monica Mountain range.
Western Transverse Ranges-Channel Island Block
Some of the oldest rocks in North America can be found on the Western Transverse Ranges-Channel Island Block. Dating these rocks are important evidence in theorizing the rotational movement of the Western Transverse Ranges-Channel Island Block. In the San Gabriel Mountains rare igneous rock known as anorthosite has been dated at 1.2 billion years old and metamorphic Gneiss has been dated at 1.7 billion years old. Similar aged rocks can be found on the eastern side of the San Andreas Fault in the Orocopia and Chocolate Mountains, just east of the Salton Sea. Likewise, the 30 to 50 million year old rhyolite found on San Miguel Island is chemically identical to the 30 to 50 million year old rhyolite found in San Diego. Additional evidence of the transverse ranges rotational movement can be found using paleomagnetism. When rocks and minerals are formed they have magnetic particles that line up with the earth’s poles. Measuring the magnetic orientation of the rocks with the Western Transverse Ranges-Channel Islands Block shows a variance of 100 degrees to the east while the matching rocks in San Diego, the Orocopia Mountains and the Chocolate Mountains point to the north.
In addition to the Western Transverse Ranges-Channel Islands Block’s clockwise rotation, the block is being compressed by the Baja California block moving northward into southern California. This compression causes faulting and folding which results in the uplifting of the Western Transverse Ranges-Channel Islands Block. The uplifting of the block has pushed the Channel Islands up out of the ocean, resulting in a continual change in the topography of the southern California coastline.
Additionally, glacial and interglacial periods have also shaped the topography of our coastlines, but at a much faster rate than plate tectonics. At the peak of the most recent ice age, just about 17,000 years ago, sea levels were approximately 400 feet lower than they are today. At the time, the four northern Channel Islands formed a single large island known as Santa Rosae. For a time it was believed that Santa Rosae may have bridged to the mainland, however, the western coastline of Santarosae never got closer than 4 to 5 miles to the mainland.
These past sea levels can be identified by locating marine terraces both above and below the surface of the ocean. Marine terraces are evidence of uplift and glacial and interglacial periods. Marine Terraces are created by the ocean waves eroding and cutting away at the surf zone which results in flat land formations that led to inland inclines. As the islands and mountains continue to rise due to uplift and sea levels continue to fluctuate due to glacial and interglacial periods, new marine terraces will continue to cut away our coastlines.
The earth’s latitudinal circumference is greatest at the equator and decreases as you move north or south away from the equator towards the poles. As the earth rotates, at any point in time, the equator is moving faster and further than it is at the poles. Because the earth rotates to the east, it causes the ocean currents to move towards the west, with the greatest amount of westward movement occurring at the equator. As you move closer to the poles drag is increased pulling the westward flowing currents at the equator towards the poles. As a result, in the northern hemisphere, ocean currents rotate clockwise and in the southern hemisphere ocean current rotate counter-clockwise. This phenomenon is known as the Coriolis Effect. Because of the Coriolis Effect, our California coastlines receive cool ocean currents originating from Alaska.
Ocean temperatures are generally stable and are not really affected by localized weather. On the other hand, localized weather is regulated by ocean temperatures and as a result, weather along the coastline is relatively stable with consistent temperatures. For example, the average daytime high’s on Santa Cruz island fluctuate only 16 degrees year round. In southern California the ocean is usually cooler than the air temperature resulting in a foggy marine layer which is good for our coastal vegetation as it provides moisture and prevents mass evaporation.
Flora: Coastal Sage Scrub
California Sagebrush (Artemisia californica)
Vegetation in southern California is referred to as chaparral, which in spanish means shrubby evergreen oaks. Closer to our coastline, vegetation is referred to as coastal sage scrub, or soft chaparral. Soft chaparral is generally softer and flexible versus harder woody plants. Because southern California only receives 10 inches of rain per year, our vegetation needs to be resistant to drought. Due to the lack of moderate rainfall one could classify the vegetation along the southern California coastlines as desert vegetation. Several plants found both along the coastline are similar to plants found in our deserts. However, our mediteranian climate along the coast prevents drought stress to our vegetation like that of desert vegetation.
Pictured is California Sagebrush (Artemisia californica). Not a true sage, the California Sagebrush is a member of the sunflower family. California Sagebrush is a drought-deciduous plant, meaning it will shed its leaves in times of drought and is generally one of the first plants to regrow its leaves and produce new shoots after winter rains. This makes the California Sagebrush an indicator species of current drought conditions.
The Peter Iredale
This image of the Peter Iredale is along the coastline of northern Oregon. While not a natural feature, I thought it was a great example of weathering that I wanted to include in this presentation. The Peter Iredale was a british ship made of steel that was on a voyage from Mexico to Portland Oregon before crashing ashore in Fort Stevens on October 25 of 1906. What you see in this image is all that remains of a large four mast sailing ship. For over 100 years it has been broken down by processes of weathering.
Some of the weathering processes that have likely broken down the Peter Iredale are a combination of wind blown sand, crashing waves, haloclasty weathering and oxidation. Wind blown sand and waves weather away at rock and materials just like sandpaper carves away at wood. Haloclasty weathering occurs when ocean saltwater gets into the cracks of rocks and materials. After the water evaporates the salt crystals left behind grow applying physical pressure on the rock a or material slowly breaking it apart. Oxidation causes a rock or material containing iron to turn to rust when the iron interacts with water and oxygen. As rust expands, it weakens and breaks down the iron.
As mentioned earlier, southern California coastal areas only receive about 10 inches of rain per year. Because of this, erosion occurs at a much slower rate in southern California than it does in comparison to some place like the Sierra Nevada’s where about a foot and a half of earth erodes every 1,000 years. Vegetation also helps slow the rate of erosion, but there are two periods in the Channel Island’s history that vegetation on the islands was greatly depleted increasing the rate of erosion. The first was 10 to 15 thousand years ago when Pygmy Mammoths grazed the islands free of vegetation which may have been the driving force behind their extinction from the islands. The second was only about a hundred years ago when ranchers inhibited the island and brought sheep and cattle with them. Once again, during years of drought these grazing animals will eat all available vegetation, including the roots. Once vegetation is removed erosion occurs much faster carving out steep canyons on the hill sides of the island depositing sediments on the beaches and into the ocean.
Crystal Cove State Park
Sedimentary rock can have distinct layers of different colors that are formed from the compaction and cementation (lithification) of sediments that have been weathered, eroded and deposited from other rocks and organic materials. Most commonly, sediments are laid down as marine sediment in parallel layers. Of the three types of rock, sedimentary is usually the softest. While only 5% of the rock within the earth’s crust is sedimentary, sedimentary rock makes up 75% of the rock at the surface of the earth.
For millions of years California was underwater. During this time sediments accumulate at the bottom of the ocean floor via the erosion processes mentioned above. Only about 1-2 million years ago did southern California’s coast ranges fully emerge from the ocean via uplifting processes mentioned earlier. While sedimentary rock generally forms in horizontal layers, sedimentary beds are not always found horizontally, but rather in deformed layers due to faulting and folding. Because sedimentary rock is relatively soft and unstable, especially along the coastal ranges, it can be easily weathered by ocean waves. The wet rock layers are also susceptible to slippage which we will see on the upcoming Mass Wasting slide.
Montaña de Oro State Park
The exposed, fractured and twisted rock at Montaña de Oro is a result of compressional forces that have caused brittle and ductile deformations that have taken place over the last 3 million years. Compressional stresses on the rock is a result of plate tectonics creating faults and folds that have pushed and squeezed the rocks. The type of deformations that have taken place here at Montaña de Oro are brittle deformation and ductile deformation. Brittle deformation is when rock breaks or is permanently bent from the compressional forces placed on the rock. Ductile deformation occurs when rock has a taffy or clay like consistency and settles into a new formation due to compressional forces. The type of deformation that occurs is dependent on time, composition, temperature and confined pressure.
We also see in this image that 40 feet above the ocean water is a marine terrace. Like we talked about earlier on the Coastline Topography slide, this is evidence of localized uplifting.
Montaña de Oro State Park
Mass wasting is a general term for earth materials sliding down slopes, like this sinkhole along the California coastline in Montaña de Oro.
Sea caves along the coastline are formed at the base of cliffs where abrasive ocean waves crash into the soft rock walls. The caves began to form when there was a crack in the cliff that was soft enough to weather away at. As the waves continue to crash into the base of a cliff wall an overhang will begin to form, and eventually into a cave. Caves are commonly cut out of softer sedimentary rock like sandstone, limestone and shale, but rarely harder rocks like granite. The rocks that make up the cliffs of Montaña de Oro are made of soft Monterey Shale. As mentioned on the Sedimentary Rock slide, sedimentary layers can slip and slide past each other when wet. After the base of this cave had eroded away, the supporting sedimentary rock slipped away leaving the soil unsupported, resulting in this sinkhole.
Plutonic rock (intrusive igneous rock) is formed beneath the surface of the earth when molten rock crystallizes and cools. This is a slow process and results in the rock being formed well before it ever reaches the surface of the earth.
30 million years ago the aforementioned oceanic Farallon Plate was subducting beneath the continental North American Plate. Near the subduction zone beneath the area of Morro Bay, a line of nine successive volcanoes that span east to west from San Luis Obispo to Morro Bay were formed. These volcanoes were active from about 20 to 26 million years ago. Today these now extinct volcanoes are known as the “Nine Sisters'”, or the “Morros”. The western most Morro is Morro Rock, which is about 21 million years old. Morro Rock itself isn’t a volcano, but a volcanic plug (or volcanic neck), similar to that of Devils Tower in Wyoming. The volcanic neck plugged the vent of the volcano that once occupied Morro Bay. The volcano dome that once occupied Morro Bay was composed of a much softer rock that has long eroded away into the ocean.
“The first people” to inhabit the Channel Islands and the California coastlines from Santa Monica to Paso Robles were the Chumash. The Chumash considered the Pacific Ocean their first home. They lived off the land and lived in dome shaped homes made of willow branches. They also used caves along the coastline for their religious ceremonies. The earlier Chumash people would use coal to make drawings of people and animals on the walls of their caves. As their culture evolved they started to use different colors for their paintings. For example, they would use the juice from the fruit of the Coastal Prickly Pear (Opuntia littoralis) as a red paint and dye.
In 1769, Gaspar de Portola on a spanish land expedition quickly established five missions in Chumash territory near Santa Barbara. With them, the spanish inadvertently brought with them european diseases that infected the Chumash and drastically killed off the Chumash population. Of the 22,000 Chumash that registered to the spanish missions, only 2,788 Chumash survived.
By 1870, the towns of Santa Barbara, Montecito, Summerland and Carpinteria began to prosper economically and became a haven for tourists and wealthy white people. The land that was promised back to the Chumash never was. The Chumash that survive the european diseases were delegated to labor work for the farmers and ranches who now took claim to their land.
The Bolsa Chica Ecological Reserve sits in the Anaheim Bay Watershed and was formed by the Newport-Inglewood Fault Line. The area was once home to ancestors of the Chumash, before it was home to the Tongva and the Acjachemen people. As mentioned on the previous slide, In the 1700’s spanish settlers started to colonize California which resulted in the death of many of the Native Americans due to european diseases. American settlers also started to head out west from the eastern United States when California became a state in 1850. In 1895 the Bolsa Chica Gun Club bought a portion of the Bolsa Chica land for hunting purposes. To improve the hunting conditions of the area, the gun club built a dam at the shore line that allowed freshwater to flow out into the ocean, but prevented salt water from flowing back into the bay of Bolsa Chica. This dam destroyed the natural ecology of the area, transforming the saltwater marsh into freshwater ponds. In 1920, oil was discovered at Bolsa Chica and the land was leased to the Standard Oil Company of California. Oil wasn’t drilled in the area until 1940 when the Signal Oil Company took over the lease. In 1942, with the threat of WWII looming, the Army built an artillery battery in Bolsa Chica for defense purposes. After the war the land was given back to its original owners.
In the 1950’s Bolsa Chica Beach became known as Tin Can Beach, this was because an estimated 300 tons of trash had been littered by visitors and squatters. In 1970 the Signal Landmark corporation purchased more than 1,700 acres of land from the heirs of the Bolsa Chica Gun Club to develop the land into residential homes and commercial property. In order to protect coastal lands and waterways, the State of California passed the Coastal Act of 1972. In 1973 the state of California acquired 310 acres from the Signal Landmark Corporation after it was determined that a manageable wetland could be reestablished at Bolsa Chica,. That same year the dam that was built by the Bolsa Chica Gun Club was replaced with a tidal gate and salt water once again flow into the bay. In 1979 the Ecological reserve was developed. By 2006 the reserve had expanded to 1,340 acres and work had begun to restore the land back to what it was in the 1800’s. Today the Bolsa Chica Reserve is a coastal estuary that includes open waters, mudflats, salt marshes, coastal dunes, islands, riparians and freshwater marshes. These habitats are home to nesting birds, land mammals, reptiles, marine life, plants and endangered species like California Seablite (Suaeda californica), Woolly Seablite (Suaeda taxifolia), Coast Woolly-Heads (Nemacaulis denudata) and Red Sand Verbena (Abronia maritima).
Newport Back Bay
Newport Back Bay is an 877 acre estuary that sits in the Lower San Diego Creek watershed and the Newport watershed. Before 1900, estuaries and coastal wetlands covered 381,000 acres in California. Today, 90% of these wetlands have been destroyed for harbors, marinas and beachfront homes. With Orange County’s population exploding in the 1960’s, plans were in development for Newport Bay to succumb the same fate as so many other estuaries and become a marina with waterfront homes. That was until 1975 when the Newport Back Bay was declared an ecological reserve and came under the management of the California Department of Fish and Wildlife.
Newport Back Bay is ideal for a wide variety of marine life, including plants, animals, amphibians, reptiles and insects. The bay is important for almost 200 different species of birds, both nesting and migrating, including endangered species like the Ridgway’s Rail (Rallus obsoletus), California Least Tern (Sterna antillarum browni), Belding’s Savannah Sparrow (Passerculus sandwichensis beldingi) and Least Bell’s Vireo (Vireo bellii pusillus).
Southern California Steelhead Trout (Oncorhynchus mykiss)
The Southern California Steelhead Trout (Oncorhynchus mykiss) is a versatile fish that once occupied every watershed in southern California that drained into the Pacific Ocean. Like salmon, they are born in freshwater rivers and streams and spend most of their adult lives in the ocean only to return to freshwater rivers and streams to spawn. Unlike salmon, the Steelhead Trout doesn’t die after spawning, but makes many trips between the ocean and freshwater rivers and streams throughout their lifetime.
Historically, the Southern California Steelhead was an important food source for the Chumash people. In the early 1900’s to the 1950’s the Southern California Steelhead was popular for sport fishing, That was up until the destruction of watersheds and the building of dams and water diversions, dimensioning free flowing rivers and streams. 90% of the trout's habitat was blocked and as a result the steelhead population declined. This along with water contamination only allows a few hundred trout to successfully spawn annually. In 1997 the Southern California Steelhead was listed as endangered under the Federal Endangered Species Act.
In 2012, the National Oceanic and Atmospheric Administration (NOAA) adopted a recovery plan for the Southern California Steelhead Trout with the goal of preventing the extinction of the Steelhead and restoring the fish population to healthy levels.
Bladderpod (Peritoma arborea)
The trophic structure determines the path food energy flows through the food chain. While food energy cannot be created, it can be transferred from one source to another. Unfortunately, when transferring energy, most of the energy is lost in the form of heat. Because all food energy on earth is generated from sunlight, there is a constant yet finite amount of light that reaches the surface of the earth, and in turn there is a finite amount of food energy that can be produced within the earth’s ecosystems.
Both plants and animals need food energy to drive cellular respiration, which is required to survive, but only plants and algae can produce energy via photosynthesis. This is why we refer to green plants as producers.
Because plants produce their own food energy, they are called autotrophs, which means self-nourishment. All other organisms need to get their food energy from plants. In general, because the transfer of energy is so inefficient, plants produce only 1% of food energy in relation to the amount of light energy received from the sun. This means that it takes 100,000 Calories of sunlight to support 1,000 Calories of vegetation.
Consumers (Rule of Tens)
California Ground Squirrel (Otospermophilus beecheyi)
Animals and insects cannot produce their own food energy required for cellular respiration. They must get their food energy from consuming other organisms. As energy flows through the food chain from organism to organism, only 10% of the food energy is absorbed from the previous organism. The remaining 90% is lost as heat energy.
A primary consumer is an organism that eats plants and gets its energy directly from vegetation, but only absorbs 10% of the light energy produced by plants. This means it takes 1,000 pounds of vegetation to support 100 pounds of primary consumers. A secondary consumer is an organism that gets its food energy by eating primary consumers, but again only absorbs about 10% of the energy within the primary consumer. Overall this means it takes 1,000 pounds of plants to support 10 pounds of a secondary consumer. The food chain continues onto tertiary consumers and quaternary consumers.
This rule of tens mathematically details how many producers and consumers at each level are required to maintain a balanced ecosystem. In a simplistic example, an ecosystem needs 25,000 pounds of vegetation to support 2,500 pounds of insects. This would support the 250 pounds of California Ground Squirrels (Otospermophilus beecheyi) needed to support 25 pounds of rattlesnakes. All these organisms are needed to support a single 2.5 pound Red-Tailed Hawk (Buteo jamaicensis).
Turkey Vultures (Cathartes aura)
Detritivores and decomposers play an important role in ecosystems as they are the final consumer in the food chain. Detritivores and decomposers include bacteria, fungi, worms, nematodes, insects, lobsters, shrimp and condors. Turkey Vultures (Cathartes aura), a condor, feed on the flesh of dead animals, known as carrion. Detritivores and decomposers dispose of carrion and prevent the potential development and spread of zoonotic diseases arising from dead animals. The importance of this cannot be more prevalent than right now, as we are in the midst of a global pandemic that in the span of a single year has infected 145 million people and killed more than 3 million people worldwide. This example alone stresses the importance of decomposers and detritivores in our ecosystem.
Like many of the other birds that we will see in this journal, the Turkey Vultures population was affected by the toxic chemical DDT. In addition to DDT, Turkey Vultures are threatened by lead poisoning accumulated from lead shots in the carcasses of dead animals left behind by hunters. They are also targeted by people who incorrectly believe they are disease spreading birds.
Active and complex, ecosystems are made up of communities of organisms that mix and interact with the living and non-living environment. Healthy ecosystems are efficient at recycling matter and do not use up all their resources.
Kelp forests produce a large diversity of life. Along with estuaries, kelp forest are among the most productive ecosystems in the world. The kelp forest around the Channel Islands are home to more than 1000 different species of organisms. Organisms are attracted to kelp forest because they provide both food and shelter. Kelp forest are found where ocean currents bring in a mix of warm water and cold nutrient-rich water from lower sea elevations. A third of the Kelp Forest of California are within the Channel Islands National Park and Channel Islands National Marine Sanctuary. In addition to the west coast of North America, kelp forest are also found off the west coast of South America, the southern end of Africa, the southern side of Australia and around the islands of Antarctica.
Kelp forests and their ecosystems are threatened by climate change, pollution, ocean acidification, invasive species, disease and the overharvesting of marine life. In Southern California, kelp forests are now half the size they were just 100 years ago. Monitoring programs by the California Fish and Wildlife have helped establish Marine Protected Areas to protect the kelp forest from overfishing in effort to protect this marine ecosystem.
Short-Beaked Common Dolphin (Delphinus delphis)
The Short-Beaked Common Dolphin (Delphinus delphis) is one of the most common dolphins in the world. Known as an indicator species, the health and presence of (or lack thereof) the dolphin can tell a lot about the health of an ecosystem. The Common Dolphin is primarily abundant off the coast of California year round. Their range goes from the coastline to about 300 miles off shore where underwater ridges, seamounts, and continental shelves promote ocean upwellings with nutrient rich water. Food is abundant for the dolphins in these areas. Usually traveling in herds consisting of hundreds of individuals, the Common Dolphin may also travel in herds consisting of thousands of other Common Dolphins. These large herds are called mega-pods, which is what we witnessed on my trip to the Channel Islands. While the Common Dolphin is not threatened as endangered, they are protected under the Marine Mammal Act. The most common threat to the Common Dolphin is being caught as bycatch of commercial fishing and being hunted for their meat and oil in Japan, Russia, and countries bordering the Mediteranian and Black Seas.
Crystal Cove Tide Pools
A community is composed of different populations of animals, plants, fungi and bacteria that live and interact with one another in a particular place to establish a stable ecosystem. The organisms that make up a community are not just a random selection of organisms, but organisms that have a fundamental dependence on one another. These dependencies include nutritional, reproductive and protective interdependence. The relationships between any two organisms within a community that have a dependence on one another are called symbiotic relationships.
In the following slides we are going to look at the symbiotic relationships of organisms that can be found in tide pools like the Solitary Green Sea Anemone (Anthopleura xanthogrammica) and the Blueband Hermit Crab (Pagurus samuelis). We are also going to look at the predator-prey relationship between the Southern Sea Otter (Enhydra lutris nereis) and Sea Urchins as well as the relationships between the Purple-striped Sea Nettle (Chrysaora colorata), Slender Crabs (Cancer gracilis) and tiny amphipods and fungi and alga that form Lichen.
Solitary Green Anemone (Anthopleura xanthogrammica)
A relative of the jellyfish is the sea anemone. As such, the Solitary Green Anemone isn’t a plant, but an animal that can be found along rocky shores and tide pools. A sea anemone can move but generally remains in one place feeding on detached mussels, crabs and small fish by using the nematocysts on its tentacles to paralyze its prey. However, some fish have the ability to protect themselves from the sting of the anemone by covering themselves in a protective mucus. The Anemone also uses its tentacles to bring its prey into its mouth.
The Solitary Green Anemone has a mutualistic relationship with microalgae and dinoflagellates that live within the anemones tissues. This relationship benefits both organisms as the anemone acquires food energy from the algae via photosynthesis and the algae gets protection and a safe place to live. When the anemone is in a shaded area and doesn’t receive enough light, the microalgae may not be present in the anemone and the anemone will be a pale color versus a vibrant green.
Commensalism & Mutualism
Blueband Hermit Crab (Pagurus samuelis)
Another tidepool organism is the hermit crab. The Blueband Hermit Crab has a commensalistic relationship with sea snails. This means the hermit crab benefits from the sea snail by using their shells for protection from predators like Pile Perch (Rhacochilus vacca), sheephead Semicossyphus pulcher), and Spotted Kelpfish (Gibbonsia elegans). The sea snail is not affected by this relationship because hermit crabs don’t kill sea snails for their shells but only use the shells of dead sea snails, which can remain strong for decades. The Blueband Hermit Crab prefers the shell of the black turban snail (Tegula funebralis), as seen in this image.
Some species of hermit crabs also have a mutualistic relationship with sea anemone’s. Hermit crabs can carry sea anemones on their shell providing themselves with additional protection from predators. The hermit crab will even transfer the sea anemone to new larger shells when they outgrow their smaller shells. In return, the sea anemone gets free transportation and eats the leftovers of the crabs' food.
Southern Sea Otter (Enhydra lutris nereis)
A keystone species maintains the diversity and health of a community by reducing the amount of competitors within a community. Removing a keystone species would dramatically affect the makeup of a community and/or ecosystem.
The Southern Sea Otter is found in kelp forest and estuaries off the California coastline between Half Moon Bay and Santa Barbara. Sea otters are the smallest of all marine animals and unlike other marine animals, they do not have blubber to keep themselves warm. To keep themselves warm they eat a lot to fuel their metabolism. Sea otters eat 25%-35% of their body weight a day. This can equate up to 15 pounds of food a day. A favorite food of sea otters is sea urchins and crabs. It is important that sea otters feed on sea urchins because sea urchins eat kelp and algae. If left unchecked, sea urchins can destroy a kelp forest and as a result reduce the marine life that depends on the kelp forest for survival. Thus the elimination of the sea otter would destroy the entire ecosystem of a kelp forest. The Southern Sea Otter is currently listed as endangered but not because of its natural predators like the Great White Shark (Carcharodon carcharias) and Killer Whale (Orcinus orca), but because of hazards introduced by humans like toxic chemicals, climate change, overfishing and oil spills. Because the sea otter population is condensed to a small range, a localized hazard could kill the entire population.
Parasitism & Mutualism
Purple Striped Sea Nettle (Chrysaora colorata)
The Purple-striped Sea Nettle is a jellyfish that can be found in open waters off the coast of California and near deep ocean oil rigs. The Purple-striped Sea Nettle has a symbiotic relationship with two different organisms. One being a parasitic relationship with tiny amphipods and the other being a mutualistic relationship with juvenile Slender Crabs. The relationship with the tiny amphipods benefits the amphipods as it feeds on the Purple-striped Sea Nettle but obviously harms the Purple-striped Sea Nettle as the tiny amphipods chew and feed on it. The Purple-striped Sea Nettle’s relationship with the juvenile Slender Crab benefits both the Purple-striped Sea Nettle and the Slender Crab. The Slender Crab travels with the Purple-striped Sea Nettle hanging to its tentacles and inside its bell feeding on the tiny parasitic amphipods. Here, both the Purple-Striped Sea Nettle and and the Slender Crab benefit from the relationship. The Slender Crab gets room and board and the Purple-striped Sea Nettle is freed from the tiny parasitic amphipods.
Lichen isn’t a single organism, but two or more organisms that have formed a mutualistic relationship that benefits the organisms involved to survive as a single unit. The organisms that make up a lichen unit are most commonly an ascomycete fungus and a green or blue-green algae known as cyanobacteria. Within the last five years it has been discovered that there is a third organism present in many lichen as well, a basidiomycete yeast. In this relationship the fungus forms the body of the unit protecting the algae and giving the lichen its physical characteristics like shape, size and color. The yeast that makes up the cortex of the fungus also adds to the physical characteristics. Algae benefits because on its own it can only survive in water, but when paired with a fungus to form a lichen, algae gains the ability to survive anywhere in the world. A fungus is generally a decomposer and gets its food energy from the organic matter of dead organisms. However, in this relationship, the fungus benefits because the algae provides food energy for both itself and the fungus via photosynthesis. In North America alone, there are more than 3,600 different types of lichen.
Threats to coastal birds
Snowy Egret (Egretta thula)
Before the introduction of toxic chemicals to our coastal wetlands and oceans, many birds were threatened due to over hunting. Birds and their feathers were fashionable as clothing accessories. For example, in the late 1800’s to early 1900’s, 95% of the Snowy Egret (Egretta thula) and Great Egret (Ardea alba) population was killed off for their white feathers. Infact in 1886 an egret’s feathers sold for $32 an ounce, which was worth twice as much as gold at the time. Plume hunting was mostly banned in 1910. It was also fashionable to hunt Tern’s to stuff and mount onto hats. This was until 1917 when Canada passed the Migratory Birds Convention Act and when the United States passed the Migratory Bird Treaty Act in 1918.
Many coastal birds have also been severely affected and pushed to the brink of extinction because of hazards introduced by humans. In the following slides we are going to take a look at the toxic chemical DDT and how it has severely negatively affected many birds near the top of the food chain. For instance, the Brown Pelican (Pelecanus occidentalis) population dropped to under 10,000 individuals in the 1960’s and by 1970 they were placed on the endangered species list. It was so bad that by 1971, of the 552 pairs of Brown Pelicans nesting on Anacapa Island only 1 egg successfully hatched. Other toxins like heavy metals, selenium and methylmercury also affect the reproductive success of birds causing deformed embryos and chick death.
During World War II, DDT (dichloro-diphenyl- trichloroethane) was developed for the purpose of killing insects that carried malaria and typhus in the South Pacific. DDT was possibly the most powerful pesticide ever created, as it didn’t just kill one or two species of insects, but it killed all species of insects. Nature writer Edwin Way Teale warned about the pesticide, "A spray as indiscriminate as DDT can upset the economy of nature as much as a revolution upsets the social economy. Ninety percent of all insects are good, and if they are killed, things go out of kilter right away."
After WWII, DDT was made available to the public and was thought of as a new miracle compound for insect and pest control. From 1945 to 1972, DDT was sprayed everywhere, from coastlines to farmlands for the purpose of killing mosquitoes and crop destroying insects. During this time approximately 1.35 billion pounds of DDT had been sprayed on U.S. soil and the toxic chemical was transferring into our streams, lakes, rivers and eventually into our oceans via rainwater runoff. To compound the issue here in southern California, the largest producer of DDT in the United States was in Los Angeles, where 34 million pounds of DDT had been dumped into the ocean, contaminating our coastlines and the ocean waters surrounding the Channel Islands.
Bioaccumulation & Biomagnification
Brown Pelican (Pelecanus occidentalis)
Unlike energy that is lost in the process of acquiring food, toxins cannot be digested and instead are stored and accumulated within an organism. For example, if the ocean water is contaminated with DDT at 0.000003 ppm, a single zooplankton doesn’t just absorb 0.000003 ppm of DDT, but with prolonged exposure could accumulate up to 0.04 ppm of DDT. This storing of toxins is known as bioaccumulation.
Generally, organisms lower on the food chain absorb toxins directly, but it is the organisms higher up the food chain that accumulate the most toxins by a process known as biomagnification. Because a single small fish doesn’t eat just one zooplankton, but many zooplankton, a single small fish can accumulate and store 0.5 ppm of DDT. Same thing with larger fish, they don’t eat just one small fish, they eat lots of small fish and can accumulate 2 ppm of DDT. And as we look at birds like the Brown Pelicans, Bald Eagles and Ospreys that prey on larger fish, they can accumulate 25 ppm of DDT. We see how the amount of DDT is magnified from a single zooplankton to a single bird.
When absorbed, DDT is stored in the fatty tissue of animals and humans where it could lead to cancer, genetic damage and the eventual extinction of entire species. In birds DDT causes the bird's egg shells to be too soft and too thin resulting in the eggs being crushed while nesting.
Author of Silent Spring
Rachel Carson was a best-selling author and a marine biologist with the U.S. Fish and Wildlife Service and was someone who understood the dangers of the toxic chemical DDT. After being rejected multiple times by magazines declining to publish her articles, Carson went forward with writing her book, Silent Spring. In the book Carson wrote about a grim reality with no birds, no fruit trees and no children. On a CBS documentary before her death in 1964, Carson said, "Man's attitude toward nature today is critically important simply because we have now acquired a fateful power to alter and destroy nature. But man is a part of nature, and his war against nature is inevitably a war against himself. (We are) challenged as mankind has never been challenged before to prove our maturity and our mastery, not of nature, but of ourselves."
Of course, just as it would and does today, conservatives did not react well to the book. They cried ignorance, hysteria, misstatements, cultism, and communist sympathies. Carson was of course met with opposition from the chemical and agricultural industries with comments like "If man were to faithfully follow the teachings of Miss Carson, we would return to the Dark Ages, and the insects and diseases and vermin would once again inherit the earth."
Fortunately many conservationists, ecologists, biologists, social critics, reformers, and organic farmers were on the side of Carson, ready to progress and move forward to form more comprehensive and ecologically informed environmentalism. Her book eventually caught the attention of President John F. Kennedy who ordered the President's Science Advisory Committee to examine Carson’s claims which led to the banning of DDT in 1972. Carson can even be credited for the green movements we see today.
Island Foxes (Urocyon littoralis) are endemic to the Channel Islands, meaning they can’t be found anywhere else in the world but on the Channel Islands. The Island Foxes have a symbiotic relationship with the island's Bald Eagle (Haliaeetus leucocephalus) population. Through no direct interaction, the Island Foxes survival is dependent on the health and presence of the Bald Eagles. This creates a symbiotic relationship between the two species defined as commensalism. The Bald Eagle gets nothing for the Island Fox, but the Island Fox faces the threat of extinction without the Bald Eagle.
Bald Eagles were impacted by DDT and extinct from the Channel Islands. With the Bald Eagles gone, Golden Eagles (Aquila chrysaetos) began to inhabit the island and while Bald Eagles feed primarily on fish, the Golden Eagle feeds on land animals, like small Island Foxes. The Golden Eagles were quickly bringing the Island Fox to the brink of extinction. The Island Foxes population had decreased by 90% and in 2004 was listed as endangered. With less toxic oceans and a massive conservation effort, the Golden Eagles were relocated and Bald Eagles were reintroduced to the Channel Islands. With the Bald Eagles flying in the skies above the Channel Islands, Golden Eagles stay away and the Island Foxes once again have no natural predators. In 2016 the Island Fox was removed from the endangered species list!
Island Scrub Jay (Aphelocoma insularis)
Founder Effect is a type of genetic drift that results in a change to a population's gene pool. This occurs when a small group of individuals who were once part of a larger population migrate to a new environment and by chance alone, bring with them a limited amount of genetic information. Regardless of the characteristics that existed in the larger population, the new population will only have the characteristics that exist within the migrating group. These characteristics can be related to size, color, health, etc. For better or worse, the smaller the group of migrating individuals, the more likely the group will be different from the original population. Once the two populations become separated long enough, the migrating population may have changed enough to become a new species.
In the example of the Island Scrub Jay (Aphelocoma insularis), a population migrated from the mainland to Santa Cruz Island and brought with them a limited amount of alleles, while other alleles were left on the mainland forever. Some of the physical characteristics the Island Scrub Jay has that are different from its ancestor the California Scrub Jay (Aphelocoma californica) is that the Island Scrub Jay is about a third larger and more vibrant in color. Because the two populations do not interact, allopatric speciation has occurred and the Island Scrub Jay is a different species than the California Scrub Jay.
American Avocet (Recurvirostra americana)
The American Avocet (Recurvirostra americana) is recognized by its distinct upturned long and narrow bill and long and narrow legs. In the winter months the American Avocet has grey feathers on its neck and head and in the spring and summer breeding adults have a rusty color as seen in the image. These birds are common in shallow fresh and saltwater wetlands. They feed by wading in the shallow waters by swinging their bills back and forth in the water hunting for insects and crustaceans. They also eat small fish and seeds from small marine plants. Understanding how the American Avocet got its distinct physical characteristics, is important to understand how natural selection works.
In 1859, Charles Darwin proposed the idea that organisms have not always existed in their present form, but have evolved from an ancestral species by means of natural selection. Natural selection occurs when a population contains a variety of traits and has an abundance of offspring within an environment that has limited resources. The individuals that carry the traits that are best suited to survive the environment are the individuals who will survive to pass on those favorable traits. In the end, the traits that are more advantageous towards survival will become the common traits within the population. For the American Avocet, a longer bill and legs have proven favorable as they allow the bird to wade in deeper waters and allow the bird to reach deeper into the water to catch its prey.
Wild Turkeys (Meleagris gallopavo)
Sexual selection is a form of natural selection, which is a mechanism for a species’ population to evolve. Sexual selection occurs within a species that exhibits sexual dimorphism, that is when the males and the females look different from one another. With sexual selection, male only have the ability to pass on their genes when they are selected by the female. In order to be selected by the female, the male must exhibit specific traits, where it be specific movements like a dance, specific song or display a certain physical characteristic.
In the case of Wild Turkeys (Meleagris gallopavo), size apparently does matter. While male wild turkeys attempt to attract female wild turkeys by fanning their tail feathers, puffing their body feather and strutting around, a study in 1995 by the journal Animal Behaviour, found that the only trait the female turkeys appear to care about is the length of the male's snood. The snood is a nubbin of flesh that sits just above the male's beak. When the male is ready for sex, his snood swells into a puckered, dribbly noodle several inches long. In the study they found that a few millimeters of snood length was enough difference to sway most of the female turkeys. That being said, it would appear the male turkey to the right would likely be the favored male of the two.
Leopard Shark (Triakis semifasciata)
Camouflage, or cryptic coloration, allows organisms to use their colors and markings to blend in with their environment in effort to hide their location, identity and movement from their predators and or their prey.
Sharks are an excellent example of an organism that is well-adapted for its environment as they have remained relatively unchanged in terms of both behavior and physical characteristics for tens of millions of years. The type of camouflage used by sharks is known as countershading. This is when the top of an organism’s body is darker in color and the bottom of the organism’s body is lighter in color. This allows the shark to blend in with the darker ocean floor when seen from above and to blend in with the lighter water surface when seen from below.
The Leopard Shark (Triakis semifasciata) is one of the most common sharks along southern California coastline ranging from Oregon to the Gulf of California. The Leopard shark is a bottom feeder preying on fish and crabs along the ocean floor. Predators of the leopard shark are the Broadnose Sevengill Shark and humans who hunt the shark. Countershading is very important for the Leopard Shark as it hides from is prey below and its predators from above.
Humpback whales (Megaptera novaeangliae)
A K-selected species, or a specialist species, lives in relatively predictable and stable environments. They are generally larger organisms that have long life spans. They don’t reproduce until later in life, they have few offspring with greater competitive abilities and they often give extensive paternal care to their offspring. An example of a K=selected species along the California Coastline is the Humpback Whale (Megaptera novaeangliae).
Humpback whales can be found both offshore and along coastal waters almost anywhere in the world. In 1970, the Humpback Whale was listed as an endangered species under the Endangered Species Conservation Act and in again in 1973 under the Endangered Species Act. Before whaling was prohibited in 1985, the Humpback Whales global population had decreased by more than 95%. Today, there are fourteen distinct Humpback Whale populations around the world, and while the species is recovering, four of these populations are still listed as endangered and one is listed as threatened. The threatened population is the Mexico population, which is the population that is found here off the coast of California all the way up to Alaska. Humpback Whales continue to be threatened by vessel strikes, entanglement and harassment. Harassment being any vessel that causes stress to the whales. This includes recreational boats and whale watching boats, particularly here in California where whale watching is a major tourist attraction. Knowing this makes me feel kind of guilty about this image.
Exotic & Invasive Species
Iceplant (Carpobrotus edulis)
A common sight along our southern California coastlines from Humboldt County to Baja California is the exotic and invasive plant called Ice Plant (Carpobrotus edulis). Ice Plant is native to the coastlines of South Africa where the climate is similar to ours. Ice Plant was first introduced to southern California in the early 1900’s to aid in erosion control along railroads and later used by Caltrans for erosion along roadsides. Ironically, because Ice Plant has heavy leaves and a shallow root system, it can actually destabilize the soil and can contribute to landslides. Today Ice Plant is still sold in nurseries as an ornamental plant. Ice Plant is bad for the southern California coastline communities because it alters the soil composition and out competes our native plants for available sunlight, water and nutrients, including threatened and endangered species.
While Ice Plant is easy to remove because of its shallow root system, it is so widespread that it is unrealistic to remove the plant entirely but only realistic to focus on isolated areas with the dedication of volunteer and student led programs.
Schoenherr, Allan – A Natural History of California, Second Edition, University of California, University of California Press, 2017.
Robert Goodman - NAT 181A - Natural History, Spring 2021
Jennifer Alexander - BIO 105 - Biology, Spring 2021
Stefanie Mendoza - ESCI 120 - Geology, Spring 2021
BROCHURES / PAMPHLETS
National Park Service, Channel Island Interpretive Guide
The Hopeful Story of a Doomed Fox (https://youtu.be/2AVRSGkartg)
Southern California Steelhead (https://youtu.be/eR0WzInZzS0)
Geologic History of Southern Calif... (https://youtu.be/bjU2ueb1Rvg)