Anthropogenic Impacts on Bays and Watersheds. HI-MOES Presentation 2009 The Kohala Center Kohala Watershed Partnership

Transcription

1 Anthropogenic Impacts on Bays and Watersheds HI-MOES Presentation 2009 The Kohala Center Kohala Watershed Partnership

2 Some Common Terms Watershed = An area of land that drains into a common destination Bay = a part of a sea or lake that cuts into the shoreline Anthropogenic = relating to, or resulting from the influence of human beings on nature Estuary = the place where fresh and salt water mix Run-o = Rainwater that runs o surfaces such as roads, parking lots or farm fields

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4 What s in our Water? Suspended Material Dissolved Material Living Organisms

5 Ahupua a Traditional land division system All of the resources needed to sustain a community within the boundaries 600 ahupua a on Hawai i How is this similar or di erent to a watershed?

6 Kahalu u Bay Ahupua a s: Kahalu u, Keauhou 1 and Keauhou 2 Near shore and mauka resort development Cultural resources Popular snorkeling site ReefTeach and Citizen Science

7 Point source pollution Single point of discharge E.g. Sewage treatment plants

8 Non-point source pollution Many di erent sources and human activities Run-o Leading cause of water pollution in U.S. E.g. agriculture, golf courses, lawns, septic systems

9 Sediment Pollution Causes: badly managed construction sites, crop and forest lands, eroding streambanks, inadequate vegetation Impacts: Dirt, materials, sand & silt in the water Suspended sediment (cloudy water) = less sunlight Settles on habitat Clog fish gills, smothers coral etc. Photo: DAR

10 Nutrient Pollution Causes: fertilizers, livestock, pet waste, household detergents, sewage discharge Impacts: Overabundance of nutrients such as nitrogen and phosphorous leads to increased plant growth, eg algae less sunlight in water for other organisms excessive use of oxygen during decomposition

11 Bacterial Pollution Causes: sewage treatment plants, leakage from septic systems, animal manure Impacts: Certain types of bacteria can be harmful or deadly in excess fish, animals or humans that ingest the water

12 Toxic Pollution Causes: pesticides and herbicides; gasoline, oil, and other automotive products; household cleaning products; paints and solvents; battery acid; industrial waste chemicals Impacts: Chemicals that can poison or kill organisms enter water Harms organisms in or near water Can accumulate in food fish

13 Debris Mainly plastics North Pacific Garbage Patch Kamilo Beach

14 What are the anthropogenic features at Kahalu u?

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16 What Can You Do? Plant vegetation where possible to prevent run-o and soil erosion Check your car for oil leaks Use biodegradeable cleaning products

17 How do we measure water quality? Water quality monitoring is very complex! But, there are parameters that can help us understand the characteristics of the water

18 Temperature A ects ability of water to hold oxygen is in water (Oxygen more soluble in cold water) Influences rates of chemical and biological reactions (bacteria/algae grow faster in warm water) A ects ability of organisms to resist pollutants (temperature increases often harmful) Measured in degrees Coral tolerates a narrow range in temperature (16-29 C) F

19 Salinity Salt in the ocean has built over time as water moves through the hydrologic cycle Salinity is the amount of salts dissolved in water, measured in parts per thousand (ppt) Salt in the typical ocean water of the Pacific Basin is around 34 ppt but at Kahalu u, varies over time and space due to the constantly changing tides and freshwater springs High salinity can impact the ecological value of surface waters and limit usage for recreation, agriculture and industries Coral tolerates a narrow range of salinity, ppt

20 Dissolved Oxygen (DO) Amount of oxygen gas dissolved in water Important for aquatic organisms for respiration Increases by the mixing action of wind and waves Varies inversely with temperature (oxygen more soluble in cold water) When waters become polluted with nitrogen and carbon compounds they lose DO Measured in milligrams per liter (mg/l) or parts per million (ppm), percent saturation (%) In the ocean there is a large range depending on temp, tide, area

21 ph ph abbreviation representing concentration of hydrogen ions in the water ph measures how acidic or basic the water is Reported in logarithmic units (0-14) ph determines how soluble nutrients and heavy metals are, change in ph can indicate new sources of pollution sea water is normally between 8.0 and 8.4 (Basic)

22 Turbidity Measurement of water clarity, measures how much light is scattered by suspended particles while traveling through the water column Varies depending on environment, water can be cloudy from runo and sediment or because of excessive algal growth Measured in nephelometric turbidity units (NTUs) Due to the low plant productivity of most coral reef environments, water is generally very clear (<0.1 NTU)

23 Nutrients: Nitrogen Nutrients such as nitrogen and phosphorus are essential components of life that are continually recycled by plants and animals, and found in the cells of all living organisms. Excessive amounts of nutrients can drain into water and cause algal blooms and become toxic. Forms of Nitrogen Ammonia (NH 3 ): easiest form of nitrogen for plants and algae to use, continually released into water through fish gills, urine, and solid wastes, can be toxic even in low concentrations Nitrite (NO 2 ): second step of breakdown of nitrogen, nitrite is easily oxidized into to nitrate Nitrate (NO 3 ): final product produced by the breakdown of ammonia and nitrite, found in groundwater and surface waters, natural levels are low (<1mg/L), excessive nitrates can be toxic to aquatic animals

24 References Aerial Photos of Kahalu u Bay: Randy Magnus Sediment in water Insect Ahupuaa: Sewage pipes Sewage Treatment Plant Oahu Golf course Mauna Kea Honolulu Sediment on Oahu Fertilizer bag Detergent Cow Animal Manure graphic Toxic sign Paint tin Graphic of home septic system Car Battery Google Earth Plastics and Water molecule Turbidimeter Turbidity sample bottles Thermometer Bleached Coral Salt Salinity graphic