Introduction
An ecosystem is defined as the interaction of the organism and other nonliving factors in a certain community. The living components of an ecosystem, such as plants, animals, and other organisms, can be classified as the biotic component of the ecosystem, whereas the environmental conditions such as water amount, humidity, soil nourishment, temperature, and the like are termed as the abiotic factors. In an ecosystem, both the existing biotic and abiotic factors determine what kind of species live there. For example, turtles, which require a large amount of water to live in cannot possibly hope to survive in arid conditions such as deserts wherein the plants like cacti do not fit in the turtle’s habitat and the supply of water is scarce. However, it would thrive best in aquatic environments where there are algae which are part of its diet and there is an abundant supply of water.
One way to determine what kinds of animals that could possibly live optimally under a certain ecosystem is to observe the biotic and abiotic components of said ecosystem, and then conjecture what species of animals could thrive under such conditions. More often than not, the animals in an ecosystem are visible clues on what the living conditions on that certain ecosystem are.
The objective of my field trip is to determine what animals live on the San Francisco Bay Area and analyze how their environment is suitable on their living conditions and lifestyles. In order to do this, I traveled along the part of the bay area and noted the animals that I saw. I have noted several animals—some of these are terrestrial, others are aquatic, and the rest are aerial. I will give a brief description on some of the animals and analyze how they adapt to the coastal environment of the San Francisco Bay Area.
San Francisco Bay Area: An Overview
Before delving on the animals that exist in the San Francisco Bay Area, a general overview of the location is necessary in order to provide an insight on the type of ecosystem that is present there. True to its name, the San Francisco Bay Area is a bay—a body of water connected to a larger body of water, usually the ocean. However, the location is also an estuary as well. An estuary is defined as any location wherein freshwater meets with saltwater. As a result, the brackish environment of the area presents a unique ecosystem in which biotic factors adapted to the conditions can thrive. There are many smaller bodies of water found in the location such as San Pablo Bay, the Carquinez Strait, the Suisun Bay, and the delta of the Sacramento and San Joaquin rivers.
The San Francisco Bay Area has been heavily altered in order to meet the needs of the people living there. The sedimentation in the area has been slowly receding due to the Central Valley project, being confined in dams. As a result, the mudflats in the area are decreasing in depth. In addition, the levees that were once naturally occurring where made permanent in order to reduce flooding on farmlands. These farmlands, in turn, have increased the carbon content of the soil, which caused a significant decrease in soil mass. The salinity of the estuary, in turn, is set to shift, which might make considerable changes to the ecology of the area.
Lastly, there are a number of introduced species in the area. These species were not naturally occurring in the environment, but they were brought by humans for various reasons. These species have altered the food web of the environment drastically as well.
Field Trip Proper: Animals in the San Francisco Bay Area
In my investigation, I toured a part of the San Francisco Bay Area and noted the animals that I saw. These animals can be classified into three types: terrestrial, aquatic, and aerial. There are a number of mammals, birds, and other organisms that were seen on the tour, and some of them will be presented below. In addition, a brief overview of the species will be given and their contribution to the ecology of the location will be discussed.
Terrestrial Organisms
In my tour, I observed a great amount of terrestrial organisms, such as beavers, chipmunks, rats, squirrels, coyotes, and foxes. There are also marine mammals present, such as seals and otters. In this report, the main mammals in the area—the beavers, seals, and otters will be discussed.
Beavers. Because the area is close to a coastal environment, it is not surprising that there is a great amount of beavers in the location. The kind of beaver that is found in the San Francisco Bay Area is called the mountain beaver, and it is a kind of primitive rodent that is nocturnal. It lives in underground burrows, only coming out at night to feed on plants. The mountain beaver that is found in the area is found in Point Reyes (Aplodontiarufaphaea) is endemic; it can only be found in that location. While classified as a point of least concern, the population of beavers in the area is still recovering because of the Vision Fire of 1995 which burned down 40% of the habitat of the mountain beaver (“Mountain Beavers”, n.d.).
Otters. Aside from beavers, other mammals which are expected in a coastal environment such as this are seals and otters. The sea otter (Enhydralutris) can be considered as an icon of the California coast itself; it is considered as the aquatic relative of the weasels. The sea otter is known for its thick coat of fur, and it feeds primarily on other aquatic organisms such as sea urchins, mollusks, and fish. Other interesting facts about these animals include being social organisms, and attaching themselves to seaweeds and kelp before swimming in order to keep being drifted away by waves. Because of their fur, these otters have been hunted nearly to extinction by humans, placing their population at about 1,000 to 2,000 as of date and putting them in the endangered list. Sea otters can be found in Big Sur and Half Moon Bay, and very rarely in Tomales Bay and Richardson Bay (“Sea Otter – Enhydralutris”, n.d). Aside from sea otters, river otters (Lontracanadensis) are also found in the area, particularly at Muir Beach.
Seals. There are also sea lions in the San Francisco bay Area. They are found in great numbers during the winter months, because of the abundance of herring in the waters. Sea lions have been known to frequent Pier 39’s K-dock because aside from having plenty of food nearby, it is not frequented by sharks and orca, their main predators. The docks provide a more comfortable shelter for sea lions than beaches because they simply have to perch on the floating docks rather than scramble on rocks when the tide changes. Sea lions are only found in the K-dock in late July to mid-May; in June and July they head off to their breeding grounds down south. Like sea otters, sea lions are social animals and they subsist on a diet of fish. The sea lions population in the bay are primarily males; the juveniles are often see “fighting” with each other. Interestingly enough, the presence of sea lions in the area was made possible by human intervention. Boats used to dock at the K-dock, but it was proven impossible because of the abundance of sea lions in the area. Proposals were made in an attempt to remove the sea lion population in the area, but it was eventually decided to forsake the area in order to give way for the sea lion population to thrive. The presence of many sea lions has caused the original dock to creak and become waterlogged. Many floats have been introduced in the area for sea lions as well (“Sea Lion Q & A”).
These three animals—beavers, otters, and sea lions—were once used by humans in the fur trade, particularly the California Fur Rush of 1849. These animals were exploited to a great extent that otters faced the brink of extinction, as described above. Fortunately, these animals are slowly recovering and repopulating along the community, with help from various animal and conservative groups (Im, 2013).
Aside from mammals, there are also other terrestrial animals found, such as spiders, snakes, lizards, and some insects.
Aquatic Animals
Being a body of water, the San Francisco Bay Area is also home to a lot of aquatic organisms such as fish, crustaceans, jellyfishes, amphibians, and reptiles. The brackish environment means that there are freshwater and saltwater areas in the area as well, therefore there is a great amount of marine wildlife in the area.
Fishes. Fishes are abundant in the San Francisco Bay Area. The location is home to freshwater fish such as the lamprey, sucker, blackfish, pickleminnow, bullhead, goldfish, and perch; saltwater fish such as sharks, rays, skates, ocean sunfish, herring, shad, smelt, hake, bass, greenling, goby, halibut, sanddab, sole, tomcod, and mackerel; and fish that exist both in freshwater and saltwater like the stickleback, splittail, sculpin, goby, and flounder. Some anadromous fish—fish that start out in freshwater areas, migrate to saltwater, and come back to freshwater to breed—such as trout, salmon, and sturgeon are also found here (“Fish of San Francisco Bay Area”).
Amphibians. Aside from fishes, reptiles and amphibians are also found in the area. Some amphibians that I found during my trip were frogs, toads, and salamanders. Species of frogs in the area include the Sierrantreefrog, Californian red-legged frog, foothill yellow-legged frog, American bullfrog, and African clawed frog. Toads, on the other hand, include the Western Toad and Western spadefoot. The American bullfrog (Rana catesbiana) and the African clawed frog (Xenopuslaevis) in particular are not native species; rather, they were introduced in the area. The former is not available to California, while the latter is not native to the USA (“Amphibians of San Francisco Bay Area”, n.d.) Frogs and toads in the area are found all year, and are often seen in water.
Reptiles. There are also aquatic reptiles in the San Francisco, namely turtles and tortoises. The turtles are active during sunny days, and can usually be found during February to October. Some of the species of turtle in the area include the Western pond turtle (Actinemys sp.), red-eared slider (Trachemysscriptaelegans), Texas spiny softshell (Apalonespinifera), and the rare green sea turtle (Cheloniamydas(“). These turtles are found in different locations in the area, and are commonly seen basking in water or slightly submerged. There are also salamanders and newts in the area. The salamanders are mainly nocturnal, and are commonly seen during the rainy seasons where they usually burrow out of their habitat (“Reptiles and Amphibians of the San Francisco Bay Area”).
Jellyfishes. Jellyfishes are not common in the San Francisco Bay Area until recently. There are found in areas such as Chesaspeake Bay, wherein they subsist on fish and planktons alike. Jellyfishes commonly found in the area include moon jellies (Aurelia arita) who typically live up to one year old and are found along the Northern California coast, and the Pacific sea nettles (Chrysaorafuscescens), medusivores which are found along the Califonian and Oregon coast (“Jellies”, n.d.).
Mammals. Occasionally a marine mammal such as dolphin, orca, or whale can be seen breaching the oceanic waters as well. These animals can be better observed by taking a boat trip to the ocean itself. Examples of whales that exist along the bay area include gray whale, humpback whale, sperm whale, killer whale, and beaked whale, while dolphins and porpoises include white-sided dolphin, common dolphin, rough-toothed dolphin, Risso’s dolphin, bottlenose dolphin, Dall’s porpoise, and harbor porpoise (“Marine Mammals of the Bay Area”, n.d.)
Aerial Organisms
Because of the rich diversity of wildlife in the San Francisco Bay Area, it is no wonder that there is also a great amount of birds, insects, and the like that are to be found there as well.
Birds. The San Francisco Bay Area has been classified as a Western Hemisphere Shorebird Reserve Network (WHSRN) Site of Importance, which means that its environment is diverse enough to support a vast array of bird species. Birds in the San Francisco Bay Area can be classified according to the type of habitat they are found in. Bay water, or open water, is home to many waterbirds that subsist on fish, marine organisms or aquatic animals. Some of the birds that are found here include the grebe, pelican, cormorant, canvasback, scaup, scoter, bufflehead, and duck. Mudflats are home to tiny creatures living in the mud, which are nourished by the tide coming in and out daily. These creatures are the prey of birds such as herons, egrets, geese, mallards, pintails, wigeons, shovelers, coots, plovers, falcons, among others. Marshes are another habitant for San Francisco Bay Area birds, serving as habitats for species such as rails, wrens, yellowthroats, and sparrows. Lastly, upland habitats, such as oak and riparian habitats are also home to many species of birds. Riparian is the term for plants found in near creeks and rivers, while oakland habitats are characterized by the major presence of oak trees. Birds in upland habitats include the vulture, harrier, kite, hawk, mourning dove, owl, hummingbird, kingfisher, raven, crow, swallow, warbler, lark, blackbird, and goldfinch (PRBO Conversation Science, 2008).
San Francisco Bay Area: Invasive Species
As mentioned earlier, human activities in the San Francisco bay Area has dramatically altered the ecosystem in the area. Some of these changes include introduction of non-native species, some of which invade the natural ecosystem and pose a threat to the native species. In fact, the area has the most amount of non-native species in the world, which were mainly sent by ballast water coming from the multitude of ships passing from and to the waters of the coast. Invasive species can also be introduced via methods such as attachment to ships and boats that travel along the Californian coast. Some invasive species include Japanese gobies, Asian clams, Chinese mitten crabs, New Zealand slugs, Argentine ant, and the like. The success of these species to invade the San Francisco habitat can be attributed to the lack of biodiversity and the young age of the area (Prado, 2008).
Conclusion
The San Francisco Bay Area is a coastal environment which sports a wide array of biotic factors, including animals. The estuary environment of the area has allowed it to house freshwater and saltwater organisms, and its rich flora has made many animals possible to thrive here. In addition, human activities has altered the environment as well, threatening some native species while allowing the proliferation of invasive ones. Animals that can be found in this area include mammals such as whales, seals, otters, beavers, and dolphins, many types of fishes, aquatic animals such as jellyfishes, amphibians and reptiles, turtles, and many species of birds. There are also many non-native species in here as well, some of which pose a threat to the ecosystem at large.
All in all, it can be said that my trip along the San Francisco Bay Area has been an eye-opener to the diversity of wildlife in the area. It is amazing to know that the location itself has a vast collection of animals, which means that the Californian environment is truly rich when it comes to environmental resources.
References
“Amphibians of San Francisco Bay Area” (n.d.) Sfbaywildlife.info. Retrieved from http://sfbaywildlife.info/species/amphibians.htm
“Fish of San Francisco Bay Area” (n.d.). Sfbaywildlife.info. Retrieved from http://sfbaywildlife.info/species/fish.htm
Im, S. (2013). California fur rush. San Francisco Digital Archive. Retrieved from http://www.foundsf.org/index.php?title=California_Fur_Rush
“Jellies” (n.d.). Aquarium of the Bay. Retrieved from http://aquariumofthebay.org/pages/detail/386
“Mammals: Mountain Beavers” (n.d.). San Francisco Bay Area National Parks Science and Learning. Retrieved from http://www.sfnps.org/mountain_beavers
“Marine Mammals of San Francisco Bay Area” (n.d.). Sfbaywildlife.info. Retrieved from http://sfbaywildlife.info/species/marine_mammals.htm#pinnipeds
Prado, M. (2008). San Francisco Bay has most non-native species in world. Marinij. Retrieved from http://www.marinij.com/article/ZZ/20080222/NEWS/802229970
PRBO Conversation Science (2008). Pocket guide to the birds of San Francisco Bay. Point Blue. Retrieved from http://www.pointblue.org/uploads/assets/education/SFBayBirdPocketGuide4webPDFreduced.pdf
“Reptiles and Amphibians of the San Francisco Bay Area” (n.d.). CaliforniaHerps. Retrieved from http://www.californiaherps.com/identification/bayareaherps.html
“Sea Lion Q & A” (n.d.). Pier 39. Retrieved from http://www.pier39.com/home/the-sea-lion-story/sea-lion-qa/
“Sea Otter – Enhydralutris” (n.d.). Sfbaywildlife.info. Retrieved from http://sfbaywildlife.info/species/sea_otter.htm
