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Ballona Wetlands

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An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea . Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone . Estuaries are subject both to marine influences such as tides , waves , and the influx of saline water , and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment , making estuaries among the most productive natural habitats in the world.

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71-464: Ballona Wetlands Ecological Reserve (pronunciation: "Bah-yo-nuh" or "Buy-yo-nah") is a protected area that once served as the natural estuary for neighboring Ballona Creek . The 577-acre (2.34 km) site is located in Los Angeles County , California , just south of Marina del Rey . Ballona—the second-largest open space within the city limits of Los Angeles, behind Griffith Park —is owned by

142-521: A .75-mile (1.21 km) (one-way) walking path along Jefferson and Lincoln Boulevards. Parking is available along Jefferson but those spots are often occupied by boondocking RVs. Additional parking is often available near Ballona Discovery Park in Playa Vista. Big Blue Bus line 3 and [REDACTED] Metro bus line 115 serve this location. Ballona Saltwater Marsh is closed to the public, however Friends of Ballona Wetlands offers regular guided tours and

213-578: A dozen species of dragonfly and a half-dozen additional damselflies . Five species of bumblebee , including Crotch's bumblebee (identified as a "species of greatest conservation need" by California Department of Fish and Wildlife ), have been documented at the Wetlands. There are several reptile species present, including the San Diego legless lizard and a geographically isolated population of Southern Pacific rattlesnakes . A population of introduced red foxes

284-456: A facility in Area B related to underground natural gas; oil drilling of the land took place in the 20th century and infrastructure from that era remains. Ballona Freshwater Marsh (BFM) is a 26.1-acre (106,000 m) marsh fed by water from the nearby Bluff Creek, a remnant of Centinela Creek. The freshwater marsh, located on the corner of Lincoln and Jefferson, was built in 2003 by the corporation that

355-542: A few miles out of Los Angeles…Before Playa Del Rey was thrust on an unwilling market, when it was plain old Ballona, and the sea was not assisted to flow over the mud-covered flats, the plover there were simply uncountable at low tide. It is the best beach—except Newport—to hunt them now but what it was and what it is are vastly different. Bird species of special interest observed in the reserve include nesting pairs of Belding's Savannah sparrow and foraging California least terns . The wetlands and surrounding waterways support

426-573: A harsh environment for organisms. Sediment often settles in intertidal mudflats which are extremely difficult to colonize. No points of attachment exist for algae , so vegetation based habitat is not established. Sediment can also clog feeding and respiratory structures of species, and special adaptations exist within mudflat species to cope with this problem. Lastly, dissolved oxygen variation can cause problems for life forms. Nutrient-rich sediment from human-made sources can promote primary production life cycles, perhaps leading to eventual decay removing

497-541: A nearby stable in the late afternoons, and children and youngsters go with their classes to learn about ecology." In 1995, as the development process for Playa Vista was underway, the L.A. Times ' nutshell history of Ballona's 20th century was this: "The Ballona Wetlands, near Marina Del Rey, are about all that remains of 1800 acres of marsh that once stretched from Venice south to the bluffs of Playa Del Rey, providing natural flood control and sustaining hundreds of plant and animal species. Construction of Ballona Creek in

568-529: A number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff; however the freshwater inflow may not be perennial, the connection to the sea may be closed for part of the year and tidal influence may be negligible". This broad definition also includes fjords , lagoons , river mouths , and tidal creeks . An estuary

639-474: A state of California summary, "The project's restoration components include a net increase of approximately 200 acres (0.81 km) of coastal wetlands, replacing approximately 9,800 feet (3,000 m) of existing Ballona Creek levees with transitional zones to accommodate for sea-level rise , realigning the existing Ballona Creek channel with a more natural meander shape through the project reach/re-established floodplain, and improving tidal circulation into

710-408: A type of ecosystem in some estuaries that have been negatively impacted by eutrophication. Cordgrass vegetation dominates the salt marsh landscape. Excess nutrients allow the plants to grow at greater rates in above ground biomass, however less energy is allocated to the roots since nutrients is abundant. This leads to a lower biomass in the vegetation below ground which destabilizes the banks of

781-550: A well-mixed water column and the disappearance of the vertical salinity gradient . The freshwater-seawater boundary is eliminated due to the intense turbulent mixing and eddy effects . The lower reaches of Delaware Bay and the Raritan River in New Jersey are examples of vertically homogeneous estuaries. Inverse estuaries occur in dry climates where evaporation greatly exceeds the inflow of freshwater. A salinity maximum zone

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852-436: A wholly marine embayment to any of the other estuary types. The most important variable characteristics of estuary water are the concentration of dissolved oxygen, salinity and sediment load. There is extreme spatial variability in salinity, with a range of near-zero at the tidal limit of tributary rivers to 3.4% at the estuary mouth. At any one point, the salinity will vary considerably over time and seasons, making it

923-470: A wide effect on the surrounding water bodies.  In turn, this can decrease fishing industry sales in one area and across the country. Production in 2016 from recreational and commercial fishing contributes billions of dollars to the United States' gross domestic product (GDP). A decrease in production within this industry can affect any of the 1.7 million people the fishing industry employs yearly across

994-600: Is a "fragile, self-sustaining bog, fed by both fresh and salt water…This and other major wetlands of the Los Angeles Basin, including Bixby Slough …have been largely filled in for urban development." The value of Ballona is that "wetlands teem with life and are among the earth's most productive environments." The original extent of Ballona Wetlands likely ranged between 1,500 acres (6.1 km) and 2,100 acres (8.5 km). The wetlands can be roughly divided into five ecologically distinct areas: saltwater marsh (wetland fed by

1065-455: Is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides . The effects of tides on estuaries can show nonlinear effects on the movement of water which can have important impacts on the ecosystem and waterflow. The seawater entering the estuary is diluted by the fresh water flowing from rivers and streams. The pattern of dilution varies between different estuaries and depends on

1136-509: Is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus , meaning tide. There have been many definitions proposed to describe an estuary. The most widely accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which seawater is measurably diluted with freshwater derived from land drainage". However, this definition excludes

1207-411: Is formed, and both riverine and oceanic water flow close to the surface towards this zone. This water is pushed downward and spreads along the bottom in both the seaward and landward direction. Examples of an inverse estuary are Spencer Gulf , South Australia, Saloum River and Casamance River , Senegal. Estuary type varies dramatically depending on freshwater input, and is capable of changing from

1278-560: Is less restricted, and there is a slow but steady exchange of water between the estuary and the ocean. Fjord-type estuaries can be found along the coasts of Alaska , the Puget Sound region of western Washington state , British Columbia , eastern Canada, Greenland , Iceland , New Zealand, and Norway. These estuaries are formed by subsidence or land cut off from the ocean by land movement associated with faulting , volcanoes , and landslides . Inundation from eustatic sea-level rise during

1349-639: Is the whitefish species from the European Alps . Eutrophication reduced the oxygen levels in their habitats so greatly that whitefish eggs could not survive, causing local extinctions. However, some animals, such as carnivorous fish, tend to do well in nutrient-enriched environments and can benefit from eutrophication. This can be seen in populations of bass or pikes. Eutrophication can affect many marine habitats which can lead to economic consequences. The commercial fishing industry relies upon estuaries for approximately 68 percent of their catch by value because of

1420-751: The Friends of the Ballona Wetlands , Heal the Bay , the Bay Foundation , SoCal Gas and SoCal Edison . Groups opposed include the Los Angeles Audubon Society , Grassroots Coalition , and Ballona Wetlands Land Trust . One guide to day trips in the South Bay area of Los Angeles reported, "The beauty of this hike is understated. Two major roadways run beside the property, and CA 90 also drones and howls to

1491-719: The Holocene Epoch has also contributed to the formation of these estuaries. There are only a small number of tectonically produced estuaries; one example is the San Francisco Bay , which was formed by the crustal movements of the San Andreas Fault system causing the inundation of the lower reaches of the Sacramento and San Joaquin rivers . In this type of estuary, river output greatly exceeds marine input and tidal effects have minor importance. Freshwater floats on top of

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1562-468: The Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays , harbors , lagoons , inlets , or sounds , although some of these water bodies do not strictly meet

1633-595: The Mandovi estuary in Goa during the monsoon period. As tidal forcing increases, river output becomes less than the marine input. Here, current induced turbulence causes mixing of the whole water column such that salinity varies more longitudinally rather than vertically, leading to a moderately stratified condition. Examples include the Chesapeake Bay and Narragansett Bay . Tidal mixing forces exceed river output, resulting in

1704-628: The Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast . Bar-built estuaries are found in a place where the deposition of sediment has kept pace with rising sea levels so that the estuaries are shallow and separated from the sea by sand spits or barrier islands. They are relatively common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches ( barrier islands and barrier spits ). Formation of barrier beaches partially encloses

1775-506: The Mud Hen . Spanish games took place in the spring, when a channel was cut from the laguna to allow the overflow water to escape into the ocean, at the point now known as Playa del Rey.” The wetlands as they stood in 1887 were of interest because of the nascent plans for Port Ballona : Also in 1887, "the great marsh of Ballona" was viewed as a resource for "persons living at Santa Monica." There were multiple recreational hunting operations on

1846-702: The Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross-section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River , Chesapeake Bay , and Delaware Bay along

1917-426: The bald eagle that visited the winter of 1977-78) aside, the majority of the bird population at water's edge are "the more common plovers , willets , sanderlings , curlews and killdeer ." The myriad of shorebirds that dot our sand spits and mud flats, and even inland marshes, go for the most part undisturbed. He who would find himself the shorebirds should hie himself to the mud flats and boggy marsh lands lying

1988-478: The black-tailed godwit , rely on estuaries. Two of the main challenges of estuarine life are the variability in salinity and sedimentation . Many species of fish and invertebrates have various methods to control or conform to the shifts in salt concentrations and are termed osmoconformers and osmoregulators . Many animals also burrow to avoid predation and to live in a more stable sedimental environment. However, large numbers of bacteria are found within

2059-669: The 1930s began the process of wetland degradation; construction of the Marina in the 1960s just about completed it." An extensive planning and public process for the restoration of the Ballona Reserve began in 2004. In December 2020, California Department of Fish and Wildlife certified the final environmental impact report for the Ballona Wetlands Restoration Project and selected a preferred alternative. On May 17, 2023, Los Angeles Superior Court Judge James Chalfant ordered

2130-535: The 1990s, when they became some of the last farm fields in the Los Angeles Basin. In the first decade of the 21st century the Hughes Airport land was developed as Playa Vista , a neighborhood east of Lincoln Boulevard . The remaining open space of what was once the vast Rancho la Ballona has been the subject of a battle between developers and environmentalists that has been ongoing for decades. Eighty-three acres (340,000 m) of estuarine wetland were included in

2201-528: The Audubon Society hosts monthly bird walks. The saltwater marsh tours are accessible from an entrance in Playa Del Rey. Tours of this area usually stop at an observation deck built on the old Pacific Electric Red Car berm. [REDACTED] Metro bus route 115 serves this area, and a limited amount of parking is available behind Gordon's Market. Estuary Most existing estuaries formed during

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2272-602: The Pacific Flyway—one of the largest north-south migrations of waterfowl in the world." Birders visiting the marsh "often spot red-throated loons , herons , tree swallows , barn swallows , hummingbirds and red-tailed hawks who like to surf the air." The green heron , great blue heron and snowy egret are also frequent sights at Ballona (with urban woodland trees alongside roadsides and buildings serving as rookeries). The shorebirds visit to feed on "clams, snails, crabs, worms, and shrimp." Birds generally uncommon to

2343-400: The United States. Estuaries are incredibly dynamic systems, where temperature, salinity, turbidity, depth and flow all change daily in response to the tides. This dynamism makes estuaries highly productive habitats, but also make it difficult for many species to survive year-round. As a result, estuaries large and small experience strong seasonal variation in their fish communities. In winter,

2414-513: The above definition of an estuary and could be fully saline. Many estuaries suffer degeneration from a variety of factors including soil erosion , deforestation , overgrazing , overfishing and the filling of wetlands. Eutrophication may lead to excessive nutrients from sewage and animal wastes; pollutants including heavy metals , polychlorinated biphenyls , radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion. The word "estuary"

2485-490: The adjacent city-owned lagoons are a stop along the migratory Pacific Flyway . Migratory birds "rest and feed in wetlands, the only environment in which most species can find adequate food…Salt-water flooding offers birds a rich source of food, inviting both shore and land-dwelling migratory birds." Some 90 percent of wetlands in Los Angeles County have been destroyed, and "the missing wetlands are missing steppingstones in

2556-427: The approved plan, SoCalGas will cap 16 oil wells and remove "accompanying service roads, concrete and infrastructure"; six monitoring wells will be installed to meet regulatory requirements. Conflict persists about Ballona restoration projects. UCLA sustainability professor Jon Christensen commented about the disagreement in 2020: Stakeholders in favor of the plan include California Department of Fish and Wildlife ,

2627-469: The area may appear in the Ballona watershed: "Here you'll see many surfbirds . Look for wandering tattlers , black oystercatchers , pelicans , scoters , loons and grebes . You may see the harlequin duck , Eastern kingbird and gray vireo , and there are many warblers , including the prairie warbler . Golden plovers , white-tailed kites and short-eared owls inhabit the mud flats." Rarities (such as

2698-399: The birds. They're also fish nurseries, water and air filtration systems, places for groundwater to refill aquifers, and buffer zones that help protect human homes and other property from floods." Wetland flora includes pickleweed , alkali heath , saltgrass , salt marsh dodder , arrowgrass , glasswort , and upland species like coyote bush and goldenbush . Common introduced species in

2769-452: The bottom where they are harmless. Historically the oysters filtered the estuary's entire water volume of excess nutrients every three or four days. Today that process takes almost a year, and sediment, nutrients, and algae can cause problems in local waters. Some major rivers that run through deserts historically had vast, expansive estuaries that have been reduced to a fraction of their former size, because of dams and diversions. One example

2840-408: The construction of an estuarine harbor and port called Marina del Rey in the late 1950s, increased the 2,100-acre (8.5 km) urbanized estuary by 700 acres (2.8 km). Additional open space east of the wetlands was converted to agricultural uses by the early 20th century. Many of these farm fields became the private Hughes Airport with other fields staying under cultivation continuing well into

2911-425: The death of Howard Hughes, which would kick off the current era of Ballona's long history, the wetland was described by a resident of Playa Del Rey. She observed seven great blue herons foraging for food in the marsh at dusk, and wrote: Circa 1979: "The salt marshes on Howard Hughes Summa Corp. lands are the object of a bitter tug-of-war between developers and environmentalists. There, schoolgirls canter horses from

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2982-409: The dissolved oxygen from the water; thus hypoxic or anoxic zones can develop. Nitrogen is often the lead cause of eutrophication in estuaries in temperate zones. During a eutrophication event, biogeochemical feedback decreases the amount of available silica . These feedbacks also increase the supply of nitrogen and phosphorus, creating conditions where harmful algal blooms can persist. Given

3053-401: The ecological reserve." Site improvements included in the proposed restoration plan include two new bridges (one spanning Lincoln and one crossing Ballona Creek just west of Culver), a scenic-overlook deck, 3.6 miles (5.8 km) of bike-walk trails, 5.5 miles (8.9 km) miles of pedestrian-only access, 2,000 feet (610 m) of boardwalk, educational signage and additional parking. Under

3124-401: The effects of modifying the estuarine circulation. Fjord -type estuaries are formed in deeply eroded valleys formed by glaciers . These U-shaped estuaries typically have steep sides, rock bottoms, and underwater sills contoured by glacial movement. The estuary is shallowest at its mouth, where terminal glacial moraines or rock bars form sills that restrict water flow. In the upper reaches of

3195-595: The estuary impacted by human activities, and over time may shift the basic composition of the ecosystem, and the reversible or irreversible changes in the abiotic and biotic parts of the systems from the bottom up. For example, Chinese and Russian industrial pollution, such as phenols and heavy metals, has devastated fish stocks in the Amur River and damaged its estuary soil. Estuaries tend to be naturally eutrophic because land runoff discharges nutrients into estuaries. With human activities, land run-off also now includes

3266-424: The estuary, the depth can exceed 300 m (1,000 ft). The width-to-depth ratio is generally small. In estuaries with very shallow sills, tidal oscillations only affect the water down to the depth of the sill, and the waters deeper than that may remain stagnant for a very long time, so there is only an occasional exchange of the deep water of the estuary with the ocean. If the sill depth is deep, water circulation

3337-771: The estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries typically develop on gently sloping plains located along tectonically stable edges of continents and marginal sea coasts. They are extensive along the Atlantic and Gulf coasts of the U.S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m (13 ft). The barrier beaches that enclose bar-built estuaries have been developed in several ways: Fjords were formed where Pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross-sections. At their mouths there are typically rocks, bars or sills of glacial deposits , which have

3408-569: The final environmental impact report to be decertified. CDFW decertified the EIR on September 28, 2023, and is now proceeding to revise the document as per the court order. CDFW hopes to have a draft revised EIR available for public comment by Spring 2025 and depending on public input received on the draft revised EIR, a recertified EIR by the end of 2025, and a reapproved project. Barring further litigation and dependent of available funding, CDFW hopes to implement initial project sequences in 2026.. According to

3479-609: The fish community is dominated by hardy marine residents, and in summer a variety of marine and anadromous fishes move into and out of estuaries, capitalizing on their high productivity. Estuaries provide a critical habitat to a variety of species that rely on estuaries for life-cycle completion. Pacific Herring ( Clupea pallasii ) are known to lay their eggs in estuaries and bays, surfperch give birth in estuaries, juvenile flatfish and rockfish migrate to estuaries to rear, and anadromous salmonids and lampreys use estuaries as migration corridors. Also, migratory bird populations, such as

3550-400: The great biodiversity of this ecosystem. During an algal bloom , fishermen have noticed a significant increase in the quantity of fish. A sudden increase in primary productivity causes spikes in fish populations which leads to more oxygen being utilized. It is the continued deoxygenation of the water that then causes a decline in fish populations. These effects can begin in estuaries and have

3621-420: The impacts do not end there. Plant death alters the entire food web structure which can result in the death of animals within the afflicted biome . Estuaries are hotspots for biodiversity , containing a majority of commercial fish catch, making the impacts of eutrophication that much greater within estuaries. Some specific estuarine animals feel the effects of eutrophication more strongly than others. One example

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3692-525: The many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. Excess oxygen-depleting chemicals in the water can lead to hypoxia and the creation of dead zones . This can result in reductions in water quality, fish, and other animal populations. Overfishing also occurs. Chesapeake Bay once had a flourishing oyster population that has been almost wiped out by overfishing. Oysters filter these pollutants, and either eat them or shape them into small packets that are deposited on

3763-422: The marine environment, such as plastics , pesticides , furans , dioxins , phenols and heavy metals . Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation . They also accumulate in benthic environments, such as estuaries and bay muds : a geological record of human activities of the last century. The elemental composition of biofilm reflect areas of

3834-575: The marsh causing increased rates of erosion . A similar phenomenon occurs in mangrove swamps , which are another potential ecosystem in estuaries. An increase in nitrogen causes an increase in shoot growth and a decrease in root growth. Weaker root systems cause a mangrove tree to be less resilient in seasons of drought, which can lead to the death of the mangrove. This shift in above ground and below ground biomass caused by eutrophication could hindered plant success in these ecosystems. Across all biomes, eutrophication often results in plant death but

3905-440: The now off-balance nitrogen cycle , estuaries can be driven to phosphorus limitation instead of nitrogen limitation. Estuaries can be severely impacted by an unbalanced phosphorus cycle, as phosphorus interacts with nitrogen and silica availability. With an abundance of nutrients in the ecosystem, plants and algae overgrow and eventually decompose, which produce a significant amount of carbon dioxide. While releasing CO 2 into

3976-418: The ocean), freshwater marsh (wetland fed by creeks and streams), riparian corridor (creek bottomland), sand dunes and bluffs. Habitat types present in the wetlands include coastal prairie, coastal willow woodland, coastal shrubland, salt pannes and pools , vernal pools , and coastal urban forests. In addition to functioning as a tidal river estuary, Ballona Creek also acts as a flood control channel , and

4047-427: The seawater in a layer that gradually thins as it moves seaward. The denser seawater moves landward along the bottom of the estuary, forming a wedge-shaped layer that is thinner as it approaches land. As a velocity difference develops between the two layers, shear forces generate internal waves at the interface, mixing the seawater upward with the freshwater. An examples of a salt wedge estuary is Mississippi River and

4118-411: The sediment which has a very high oxygen demand. This reduces the levels of oxygen within the sediment often resulting in partially anoxic conditions, which can be further exacerbated by limited water flow. Phytoplankton are key primary producers in estuaries. They move with the water bodies and can be flushed in and out with the tides . Their productivity is largely dependent upon the turbidity of

4189-472: The site through at least 1910. Duck hunters were particularly keen on the marsh's green-winged teals . As of 1921, Ballona Creek "came to a dead end about a mile from the ocean" (the wetlands absorbed much of the water flow and access to the open ocean was presumably blocked by sand dunes). In 1940, Howard Hughes bought the land below the Westchester bluffs for his airport. In January 1976, four months prior to

4260-449: The state acquisition, previously privately owned by Howard Hughes , his corporate heirs and the subsequent developers of Playa Vista . Numerous environmental lawsuits and the acquisition of a part of the Wetlands by the State of California has helped to protect nearly all the open space west of Lincoln Blvd. (including all of the remaining tidal wetlands). Southern California Gas Company has

4331-585: The state of California and managed by the California Department of Fish and Wildlife . The preserve is bisected generally east-west by the Ballona Creek channel and bordered by the 90 Marina freeway to the east. Ballona Wetlands Ecological Reserve is one of the last significant wetlands or marshes left in Los Angeles County, wetlands being "areas that are periodically, seasonally or perennially flooded that also have specific types of vegetation." Ballona

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4402-451: The valley at that time and standing on the hills back of the depot , one could see the breakers rolling over the sand dunes at Playa Del Rey , about four miles south of Palms, which at that time was called William Tell's Lake." A history of Santa Monica recalled “Duck shooting on Ballona laguna and boating on the laguna were popular pastimes. The boats on the laguna known as the Pollywog and

4473-456: The volume of freshwater, the tidal range, and the extent of evaporation of the water in the estuary. Drowned river valleys are also known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. Well-studied estuaries include

4544-453: The water and atmosphere, these organisms are also intaking all or nearly all of the available oxygen creating a hypoxic environment and unbalanced oxygen cycle . The excess carbon in the form of CO 2 can lead to low pH levels and ocean acidification , which is more harmful for vulnerable coastal regions like estuaries. Eutrophication has been seen to negatively impact many plant communities in estuarine ecosystems . Salt marshes are

4615-835: The water. The main phytoplankton present are diatoms and dinoflagellates which are abundant in the sediment. A primary source of food for many organisms on estuaries, including bacteria , is detritus from the settlement of the sedimentation. Of the thirty-two largest cities in the world in the early 1990s, twenty-two were located on estuaries. As ecosystems, estuaries are under threat from human activities such as pollution and overfishing . They are also threatened by sewage, coastal settlement, land clearance and much more. Estuaries are affected by events far upstream, and concentrate materials such as pollutants and sediments. Land run-off and industrial, agricultural, and domestic waste enter rivers and are discharged into estuaries. Contaminants can be introduced which do not disintegrate rapidly in

4686-633: The west…However, this should not deter anyone from visiting the wetlands. The idea is to think of what once was and what could be." Another writer visiting the freshwater marsh observed, "Though the sound of traffic is consistent, just feet away is another world filled with plants, wildlife and the song of birds." Portions of the Ballona Wetlands Ecological Reserve can be viewed from the Ballona Creek Bike Path . Ballona Freshwater Marsh can be viewed during daylight hours from

4757-429: The wetlands are crown daisy, Canary Island palm , ice plant , pampas grass , castor bean , ripgut brome , myoporum , wild mustard and wild radish . Eight acres (32,000 m) of sand dune habitat has been restored by Friends of Ballona Wetlands volunteers. Orcutt's yellow pincushion ( Chaenactis glabriuscula var. orcuttiana ) is a rare native plant endemic to the coastal dunes of southern California that

4828-399: The wild rabbits. They used the rare pickleweed and other plants to make medicine. They buried their dead there." The origin of the placename Ballona is disputed and remains poorly understood. During the expansion of Playa Del Rey in 1911, a California paper retold this history: An "old-timer," who told stories about the area between 1876 and 1890, recalled, "There were but a few trees in

4899-603: Was building the adjacent Playa Vista neighborhood. The land had previously been a derelict celery field that supported approximately 50 bird species. The creation of the Freshwater Marsh has been described as "wildly successful, providing rich native habitat and regulated access for people, where degraded land once dominated." Some 250 species of birds have now been recorded at the Freshwater Marsh. The Ballona Wetlands are typically divided into four sections for planning and study purposes. "These marshes are more than for just

4970-491: Was newly discovered at Ballona in 2010. Ballona is recognized as an Important Birding Area by the Audubon Society and nearly 260 bird species across almost 50 taxonomical families have been observed visiting Ballona freshwater marsh alone. The total bird count for the immediate area hits 320 species when the survey area includes the wetlands, the nearby bluffs, parks and residential neighborhoods. The Ballona Wetlands and

5041-464: Was relocated in the 1990s; coyotes now regularly make themselves known in the wetlands, along the creek and in surrounding neighborhoods. Tongva artifacts and ancient human remains were found during excavation of the Playa Vista site. "To the 2,000 or so remaining Gabrieleños…the Ballona Wetlands are sacred. They made their homes near the wetlands. They ate the fish hatched in its estuaries and hunted

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