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63-744: Wallaga Lake is an estuarine lake in Bega Valley Shire in New South Wales , Australia, the largest lake in southern NSW. It is located between Bermagui to the south and between Tilba Tilba to the north, situated beneath Mount Gulaga , in the traditional lands of the Yuin people . A large section of its foreshore and catchment are within the Gulaga National Park , since Wallaga Lake National Park , Goura Nature Reserve, and Mt Dromedary Flora Reserve were combined into

126-573: 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

189-451: A minister had been the subject of complaints (not an investigation) which were dismissed in 2003 as spurious and groundless. The report did not name the minister concerned as it was deemed to be 'not in the public interest'. When Debnam failed to provide evidence to support his claims, he was censured by Parliament for misleading the House. It was subsequently reported that Debnam's source for

252-828: A minister in both the Australian and New South Wales governments. He served in the NSW Parliament from 1981 to 1988 and again from 1995 to 2007; and in the Australian Parliament from 2007 to 2010. Before his retirement from the NSW Parliament, at the 2007 state election , he held the portfolios of Attorney-General, Minister for the Environment , and Minister for the Arts; and represented the Blue Mountains electorate. Prior to his retirement from

315-529: 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

378-461: A publisher and lawyer. He worked as an ABC broadcaster, and was Executive Producer of the ABC's Department of Radio Talks and Documentaries 1970. He was also Executive Director of Australian Freedom from Hunger Campaign and Community Aid Abroad 1988–94, and advisor to Federal Minister for Administrative Services 1994–95. Debus was the member for Blue Mountains , west of Sydney , from 1981 to 1988. He

441-655: A safe seat for then sitting member Kerry Bartlett of the Liberal Party , but the redistribution made it notionally Labor; Bartlett needed a 0.5 percent swing to retain the seat. On 24 November 2007 Debus won the election for Macquarie with a strong swing to Labor as his party won government. On 29 November Kevin Rudd announced he would be part of his new ministry. He was appointed Minister for Home Affairs in Kevin Rudd 's First Rudd Ministry on 3 December 2007. This

504-408: 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

567-407: 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"

630-470: A way of helping people who live below the poverty line , and suffer from poor nutrition, particularly lack of iodine , and diseases such as heart disease and diabetes brought on partly by poor nutrition. 36°21′54″S 150°03′18″E  /  36.36500°S 150.05500°E  / -36.36500; 150.05500 Estuarine Most existing estuaries formed during the Holocene epoch with

693-563: 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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756-436: 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

819-477: 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

882-455: 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

945-513: 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

1008-411: 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

1071-566: 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

1134-740: Is the Colorado River Delta in Mexico, historically covered with marshlands and forests, but now essentially a salt flat. Bob Debus Robert John Debus AM (born 16 September 1943) is a former Australian politician who served as a member of the Australian House of Representatives and the New South Wales Legislative Assembly , representing the Labor Party . Debus has been

1197-646: 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

1260-700: The Australian Crime Commission had compiled a secret file on Debus, sparking condemnation by former and serving police officials. The file included details of his personal habits, views on police corruption and former Labor prime ministers. On 13 June 2011, Debus was appointed as a Member of the Order of Australia for service to the Parliaments of Australia and New South Wales, to the development of an emergency response framework, through contributions to legal and environmental reforms, and to

1323-744: The Fisheries Management Act 1994 (NSW) in the spirit of collaboration with the Government of New South Wales , and they have been working closely ever since. In April 2020, men from the Bermagui Wallaga Lake Djiringanj men's group launched their new hand-built net fishing boat at the lake, thus reviving an old cultural tradition, thanks to a grant from the government. Young men from the community target species like flathead , bream , and mullet , and hand over their catch to local elders . They see it as

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1386-748: 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

1449-610: 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

1512-640: 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

1575-734: 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

1638-600: The black duck , a totem connected with the elder , Umbarra (aka "King Merriman", who died in 1904), who lived on Merriman's Island (aka Merriman Island and Umbarra) in the lake. In June 1978 Guboo Ted Thomas , a leader in the campaign for Indigenous land rights in Australia , wrote to then NSW Premier Neville Wran : "We, the Aboriginal people of Wallaga Lake and members of the Yuin tribe, do hereby place before you and

1701-478: 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

1764-682: The Australian Parliament, at the 2010 federal election , he was Minister for Home Affairs in the Rudd Ministry ; and served as Member for Macquarie . Debus is a prominent member of Labor's Socialist Left faction . On 6 June 2009, Bob Debus announced his resignation from the ministry and his retirement. He did not contest the 2010 federal election. Debus was born in Ryde , New South Wales and educated at Homebush Boys High School and Sydney University , graduating in Law and Arts in 1967. He worked as

1827-624: The Government of New South Wales our claim for our Land Rights". In 2006, after a protracted battle for recognition of native title , the lake was included in a handover of the Gulaga and Biamanga National Parks to the Yuin people, to be jointly managed by the traditional owners and the NSW National Parks and Wildlife Service . The agreement was signed by then New South Wales Environment Minister Bob Debus and representatives for

1890-545: The Great Divide of Eastern Australia. On 30 October 2006, he announced that he would retire from state politics at the 2007 state election . On 16 November 2006, Debus was accused by Liberal Party leader Peter Debnam under Parliamentary Privilege of being under investigation by the Police Integrity Commission . In response the Government released a NSW Police Service report stating that

1953-489: The Minister for the Arts (between April 1995 and December 1997); the Minister for Energy, Minister for Tourism, Minister for Corrective Services and Minister Assisting the Minister for the Arts (between December 1997 and April 1999); the Minister for Energy, Minister for Tourism, Minister for Corrective Services, Minister for Emergency Services and Minister Assisting the Minister for the Arts (between April 1998 and April 1999);

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2016-586: The Minister for the Environment, Minister for Emergency Services, Minister for Corrective Services and Minister Assisting the Premier on the Arts (April 1999 and January 2001); the Attorney General, Minister for the Environment, Minister for Emergency Services, and Minister Assisting the Premier on the Arts (between June 2000 and March 2003); and the Attorney General and Minister for the Environment (between March 2003 and March 2007). Debus oversaw by far

2079-400: 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,

2142-505: The Yuin people. The island is gazetted as an Aboriginal place and is not accessible to the public. Middens and other Aboriginal artefacts have been found around the lake. Under Commonwealth native title law, Aboriginal people are allowed to fish on the lake without a State Government permit, but in around 2015 the NSW Aboriginal Fishing Rights Group decided to negotiate a cultural fishing permit under

2205-494: The accusation was a convicted bank robber and child sex offender with a long history of making unsubstantiated allegations. On 30 March 2007 Debus confirmed longstanding rumours that he would seek preselection for the Federal seat of Macquarie . The seat had been redistributed to cover most of his state seat; he'd represented nearly all of the reconfigured Macquarie's eastern portion at one time or another. It had previously been

2268-452: 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

2331-497: The control of the Aborigines Protection Board of New South Wales (APB). A 1925 account of people on the reserve tells of much fishing activity by both men and women, wood carvings which are sold to passers-by, the skilled use of the gum leaf as a musical instrument , being employed to work in the maize fields, the bora ceremony and other lore. The lake is of significance to the Yuin people , being home to

2394-409: 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

2457-401: 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

2520-601: 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

2583-424: 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

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2646-776: 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

2709-609: 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

2772-498: 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 the above definition of an estuary and could be fully saline. Many estuaries suffer degeneration from

2835-400: 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

2898-420: 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

2961-476: The larger national park . There is an island in the lake known as Merriman's Island , Merriman Island or Umbarra . The lake 's surface area is 7.8 km (3.0 sq mi), while its catchment area spans 280 km (110 sq mi), consisting mainly of Dignams Creek and Narira Creek and tributaries. While the lake itself and most of its catchment fall within the Bega Valley Shire,

3024-414: The largest ever reorganisation, expansion and re-equipment of emergency services across New South Wales. He was the longest serving environment minister in any Australian jurisdiction and oversaw the expansion of the national park system of New South Wales by over one-third . He undertook other environmental policy initiatives including the first program in Australia to successfully purchase water licences for

3087-525: 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

3150-422: 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

3213-575: 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

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3276-530: The northern part of the catchment lies within Eurobodalla Shire Council . It is classified as an Intermittently Closed and Open Lake or Lagoon (ICOLL), because the entrance of the lake sometimes allows tidal exchange from the ocean, but at other times is closed off by a sand bar at the beach. It is a popular spot for recreational fishing , sailing, bushwalking and birdwatching . The Wallaga Lake Aboriginal Station or Wallaga Lake Station,

3339-440: 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

3402-399: The restoration of environmental flows in inland rivers; cleaner production and remediation laws which included pioneering emission trading schemes to reduce pollution; and the introduction of the first Extended Producer Responsibility laws in Australia. He initiated the project to create an unbroken chain of protected areas and other lands managed for conservation to stretch 2800 km along

3465-427: 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

3528-411: 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

3591-456: 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

3654-453: 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

3717-835: 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

3780-521: Was Minister for Employment from 1984 to 1986 and Minister for Finance from 1984 to 1988. Debus was also member for Blue Mountains from 1995 to 2007. He has held several ministerial positions in the New South Wales Government, including the Minister for Finance, Co-operative Societies and Assistant Minister for Education (between 1986 and 1988); the Minister for Corrective Services, Minister for Emergency Services and Minister Assisting

3843-663: Was a new ministry, and he was responsible for domestic law enforcement, including the Australian Federal Police and the Australian Security Intelligence Organisation . On 6 June 2009, Prime Minister Kevin Rudd announced a cabinet reshuffle without Mr Debus, who, after 28 years in state and federal politics had decided to retire. Debus did not contest the 2010 federal election. It was revealed in October 2008 that

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3906-594: Was an Aboriginal reserve near the lake, was established in 1891 by the Aborigines Protection Board of New South Wales (APB). It was categorised as an "Aboriginal station" or "managed reserve", which was a type of reserve established by the APB from 1883 onwards that was managed by APB-appointed officials. Education (in the form of preparation for the workforce), rations and housing were usually provided on these reserves, and station managers tightly controlled who could, and could not, live there. The land on reserves called stations

3969-674: Was often unproductive, or there was not enough labour, and therefore little chance for the reserve to become self-sustaining. The Superintendent of the Reserve was also the teacher at the Wallaga Lake Aboriginal School that was established in March 1887. The Aboriginal population of the Tathra area was removed to an Aboriginal reserve near the lake after colonisation of the area in the early to mid 19th century, under

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