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HCC Water Quality Analysis
In this lab exercise you will be participating in an investigation of the quality of water in local rivers.
What types of pollutants may affect water of local rivers?
There are many forms of pollution derived from human (and in some cases, natural) activities. Some types of pollutants that might affect water tested in this lab exercise are described below.
Some Factors Affecting Water Quality
Water Depth: shallow water allow sunlight penetration that favors the growth of phytoplankton, zooplankton, and limu.
Water Hardness: minerals are dissolved in the rain water after it touched the ground. Water that is “hard” contains calcium and magnesium compounds. If rainwater passes through soft rock, like chalk and limestone, it picks up these minerals. If it passes through hard rocks, such as granite or peaty soil, it does not pick up these minerals and so remains soft. General guidelines for classification of water; 0 to 60 mg/l of calcium carbonate is classified as soft; 61-120 mg/l as moderately hard; and 121 to 180 mg/l are hard; and more than 180 mg/l as very hard.
Salinity: the salinity (amount of salts dissolved in brackish or seawater) fluctuates with the tides, depths and proximity to freshwater streams and springs. Salinity may range from 2 to 32 ppt.
Circulation: water circulated with the incoming tide to wash sediments out to sea and prevent stagnation and accumulation of bottom sediments. Bottom sediments are composed of silt and layer of decaying detritus or muck. These decomposing sediments take dissolved oxygen out of the water and produced hydrogen sulfides. These sediments appear as black mud that smells like rotten eggs. In areas of the pond with this decomposing layer, Apple and Kikuchi (1975) report that a hydrogen sulfide level above 3 ppm is considered injurious to young fish.
Dissolved Oxygen: dissolved oxygen levels may range from 16 to 13 ppm. The mean sea level of 7.9 ppm indicated high levels of photosynthetic activity. Like temperature, the level of dissolved oxygen will vary throughout the day with light and cloud cover.
Turbidity (water clarity): the clarity of the water is related to the presence of mineral or organic particles suspended in the water. Clear water allows sunlight to penetrate and the cooler water at the bottom to warm up. Cloudy water as a result of high turbidity reduces this sunlight and may reduce the growth rate of the limu, phytoplankton and fish.
pH:
There is great concern about the damaging effects of acid precipitation on aquatic and terrestrial ecosystems. Lakes, rivers and forests in the U.S., Canada, and Europe have suffered damage from rain, snow and fog. The acids arise
from sulfur and nitrogen oxides in air emissions. Runoff from strip mines also can
lead to acidification of waterways. Fish, invertebrates and microorganisms are all sensitive to the pH of the water in which they live. In Hawaii, our major source of acid comes from the emissions from the active volcano, Kilauea. It puts sulfur into the atmosphere and makes natural acid rain. There is also a small amount of natural hydrochloric acid (HCl) put into the atmosphere this way. Fortunately, our abundant rain and winds dilute the acid in the rain and mostly blow it out to sea, although a large desert area exists in one area of otherwise-lush Kilauea volcano due to acid fallout. The pH (degree of alkalinity or acidity) of the water is measures on a scale of 1 to 14, with 1 being the most acidic, and 14 being the most alkaline. Due to the presence of minerals in Hawaiian waters, the pH of brackish water is generally alkaline (8-9).
Water temperature: the temperature varies seasonally and throughout the day. In a healthy environment, the temperature is relatively even in the water column and ranges from 64oF to 88oF in Hawaii.
Nutrients:
Nutrients like nitrate (NO3) and phosphate (PO4) are found in common plant fertilizers that help plants grow. Normally, these chemicals act as limiting factors in an aquatic ecosystem. The most common types of nutrient pollutants (eutrophiers) include untreated sewage and fertilizer run-off because both types contain a high nitrogen and phosphorous content. When present in excess, these nutrients cause an overgrowth of algae referred to as an “algal bloom.” These blooms can decrease the clearity and light penetration, which causes limu to die. As the limu decompose, dissolved oxygen is depleted. Decreased dissolved oxygen then adversely affects the fish population. If excessive nutrients increase the phytoplankton concentration to high levels, a potentially lethal situation occurs, especially during the night, especially when there is no sunlight and no wind, or circulation.. During the evening, the phytoplankton that were making oxygen during the day, stop as the photosynthetic “machinery” shuts down. Because the phytoplankton are also alive and need oxygen to live, they begin to take up the oxygen along with the other living organisms in the water. If there is a large amount of fish, there will be almost no oxygen left in the water. This causes the fish to come to the surface of the water to breath to breathe or gasp for air. Usually in Hawaii, the tradewinds and tidal circulation reduce the chance of this occurance.
Chemical pollutants
An environmental contaminant, or toxin, is a man-made chemical that has
the ability to damage or injure organisms within an ecosystem. Environmental contaminants can come from a wide variety of sources (i.e. pesticides, sewage, herbicides, etc.) and can either directly kill an organism or move up the food chain through biomagnification.
Chemical pollutants typically can be placed into two categories: inorganic and organic pollutants. Inorganic pollutants include substances such as heavy metals (cadmium, lead, mercury, manganese) and salts (see above). Organic molecules are substances that contain carbon and hydrogen atoms, and there are many thousands of organic molecules produced through human industrial processes that can act as environmental toxins. Organic pollutants are the type of pollutant
removed by the water filters containing “activated carbon” (aka “activated charcoal”) that people commonly install in their kitchen sinks
Soil Erosion
Soil erosion from human activities near the watershed may also have a negative impact on the ecosystem. Soil washing into the water decreases the water clarity, blocking sunlight that the limu needs to grow. When the bottom sediments of soil and decayed organism matter in the water get too thick, it may cause depletion of dissolved oxygen.
Invasive Species
One of the most visible invasive plants is the introduced red mangrove (Rhizophora mangle). This small tree was introduced to Hawaii from seeds brought in from Florida in the early 1900s. Mangrove trees were introduced to the Islands to prevent soil erosion. The American Sugar Company planted seedlings on the upper slopes of Molokai. However, the mangrove quickly spread to the coastlines where it now thrives in brackish water on most of the Islands. The mangrove root system established itself within the walls of the fishpond. This causes the sediment tobe trapped, turning some fishponds into wetlands anf mudflats. Mangroves also block sunlight, preventing the growth of limu, on which ‘ama’ama (striped mullet) feed.
Invasive limu species are also spreading on the reefs and in fishponds, displacing native species and altering the species and altering these structures of the ecosystems. Two of the most common aggressive species are Gracilaria salicornia and Acanthophora specifiera.
Gateway to Hawaii Reef Algae:
Sample Table
Water Quality DataSite A / Site B
Temperature
Salinity (refractometer)
Dissolved Oxygen
Turbidity
pH (pH meter)
Water clarity (secchi disk)
Nitrate (NO3)
Plankton count
Water hardness
Tide
ID plants
Formal lab report due next week as well as questions below
Water quality Questions
- How do tides affect water temperature?
- How does water temperature affect the solubility of dissolved gasses like O2?
- What is water hardness?
- How is salinity related to water hardness?
- Why is dissolved oxygen less in saltwater than freshwater?
- When is dissolved O2 higher- day or night?
- What is the role of phytoplankton? How does phytoplankton affect the level of dissolved O2?
Assignment: LAB REPORT (due next lab)
As part of a formal lab report, discuss each water sample in terms of its overall quality and potential risk to the environment. State in which samples pollutants were identified and what type of pollutants caused the quality to drop.
How to write a formal lab report:
Step 1 - The Title Page: The title should be centered on the paper. The course name should be centered and written two spaces below the title. The date is centered two spaces below the course name. Your first name, followed by the name of your lab partners, should be in the lower right-hand corner. Typed papers with computer spell-checking make the best presentation. However, if that is not available, use black pen and make sure that your handwriting is neat. Proof read and correct minor spelling errors. Major errors may warrant recopying the page.
Step 2 - Purpose Statement: State the purpose of the lab or the hypothesis to be tested. Provide background information to assist the reader in following your objectives. Define any terms that a reader may be unsure of.
Step 3 - Materials and Procedure: The materials are listed separately. Use a short paragraph, written in third person past tense, to describe the methods used to determine the data. The paragraph should be general rather than step by step instructions.
Step 4 – Data Analysis: Present the data is some organized manner - a graph, map or table. Every entry must be clearly labeled. Graphs must be titled and axes labeled. All calculations and formulas should be presented in an organized format, with corrects units of measurements.
Step 5 - Results: Use separate paragraphs to summarize what the data for each sample is showing, identify causes and effects, use comparison and contrast, and evaluate what you have observed.
Step 6 - Discussion: The conclusion section discusses the results in the context of the entire experiment. Usually, the objectives mentioned in the "Introduction" are examined to determine whether the experiment succeeded. If the objectives were not met, you should analyze why the results were not as predicted. You need to address the following: What is the significance or meaning of the results? What were you suppose to discover from this activity? How could you apply what you have learned? Could this information be useful in predicting results for similar circumstances?
Include any possible sources of error, either in the procedure or in your techniques, especially if you did not obtain the expected results. Would your results be reproducible for others? Do not “fix” the data to meet your expectations. Finish with a summary statement - a final answer.
Step 7- References: In this section you will list any literature that you have cited in the text. List ONLY those references that you have specifically cited. References are listed in alphabetical order, by the first letter of the first author's last name.
Sample Citations:
For a Journal
Brown, E.K., Cox, E.F, Tissot, B., Jokiel, P.L., Rodgers, K.S., Smith, W.R., & Coles, S.L.(2004). Development of benthic sampling methods for the Coral Reef Assessment and Monitoring Program (CRAMP) in Hawaii. Pacific Science, 7, 145-158.
For a Book
Thurman, H. & Trujillo, A. (2008). Essentials of Oceanography (9th ed.). NJ: Prentice Hall.
For an Online Journal
Author, A. A., & Author, B. B. (Date of publication). Title of article. Title of Online Periodical, volume number(issue number if available). Retrieved from
For a Sample Lab Report visit:
Fish Identification
kākū; great barracuda / Indigenous(Sphyraena barracuda) / Indo-Pacific and Atlantic
Eats: smaller fish
Eaten by: humans, ulua
Description: silvery, long, round in cross-section, with a pointed, protruding lower jaw, two dorsal fins spaced widely apart; has a large forked tail; often has small black blotches irregularly placed on the lower side; grows to almost 6 ft.
Habitat: occurs alone or in small groups, often found in shallow water close to shore; gets into fishponds where it feeds on other fish
Did you know? In Puna on the island of Hawaiʻi, the kākū is said to have bumped against canoes, usually at night when there were lights shining from the boats. Since olden times, mahiʻai (fishers) have had a special relationship with the kākū. The mahiʻai tamed certain large kākū called ʻōpelu mama by handfeeding them. Then they trained the tamed kākū to help catch ʻōpelu. The fisher summoned his kākū by pounding in rhythm on the bottom of the canoe. His fish would swim up from the deep and follow the canoe to a school of ʻōpelu. Then fishermen lowered a large circular net and fed the ʻōpelu with cooked, grated squash. The kākū would circle the school of fish and drive them into a tight ball and then the net would be raised full of fish. The fishermen would toss the ʻōpelu mama a fish as a reward. This way of fishing is still practiced on Maui.
moi; threadifin / Indigenous(Polydactylus sexfilis) / Indo-Pacific
Eats: small fish, shrimp, crabs
Eaten by: humans, kākū ulua
Description: silver in color; has six threadlike rays on the pectoral fins; a bulbous snout; underslung mouth; distinctive sweptback fins and a deeply forked tail; grows to about 12 in. Adults are called moi; juveniles are called moi liʻi.
Habitat:Adult moi are commonly found along rugged coastal shorelines with strong wave action; juveniles are found over calmer, nearshore areas with sandy bottoms; does not swim at the surface.
Did you know? In olden days, large schools of moi were said to foretell disaster of chiefs. Moi are delicious to eat; they were highly prized by the aliʻi (chiefs) and kapu to commoners. Schools of young moi (moi liʻi) can be spotted close to shore from mid-August through October. ʻEhu moi refers to foam of sea where moi are found. Fishers call this fish the wily moi because it is difficult to catch.
āholehole; Hawaiian flagtail / Endemic(Kuhlia sandvicensis)
Eats: small fish, small crabs and shrimp, insect larvae
Eaten by: humans, larger carnivorous fish, ulua, kākū, eels
Description: bright silvery with bluish color on back, but changes color to match habitat; large scales and large eyes; 6-10 in. long
Habitat: juveniles in lower reaches of streams; adults in brackish water, tidal pools, and holes along the outer edges of the reef
Did you know? Āholehole means “sparkling” in Hawaiian. In the adult stage, it is called āhole. Hawaiians placed āholehole under house posts on the east side to keep away a kahuna who might predict trouble for the family. Hawaiians also placed offerings of a white ʻamaʻama or āholehole along with a red weke or kumu under the entrance of a new hale (home) to strip evil away. “Hole” in āhole means “to strip away.” According to one story, a chiefess in Hilo yearned for āholehole from Waiʻakolea in distant Puna. A runner delivered the fish to her wrapped in limu kala from the fishpond, and the fish was still breathing!
ulua aukea; pāpio; giant trevally / Indigenous(Caranx ignobilis) / Indo-Pacific
Eats: smaller fish, and forages on the bottom for crustaceans and other invertebrates
Eaten by: humans
Description: silvery on the sides and undersides and bluish or greenish on the back with deeply forked tails. The narrow place at the base of the tail is reinforced by specially strengthened scales called scutes; grows to over 5 ft. with a weight of up to 200 pounds.
Habitat: schools of ulua frequently patrol reefs; young fish (less than 4 in.) swim in protected bays and ponds.
Did you know? There is a Hawaiian proverb spoken in admiration of a warrior who does not give up without a struggle. ʻAʻohe ia e loaʻa aku, he ulua kāpapa no ka moana. (He cannot be caught for he is an ulua fish of the deep ocean.) The ulua's color pattern, like that of many marine animals, is dark on top and light below. This counter-shading camouflages it in open water. In the Hawaiian name, ulua aukea, “kea” means white. In old Hawai'i, this prized fish could be substituted for a human in a ceremony calling for a human sacrifice. This may have been because the word ulua refers to “man” or “sweetheart” in love songs. Hawaiian women were forbidden to eat ulua.
pualu; yellowfin surgeonfish / Indigenous(Acanthurus xanthopterus) / East Africa to the Americas
Eats: phytoplankton and zooplankton (when young), limu growing on sandy bottoms
Eaten by: larger carnivorous fish
Description: oval, compressed (thin) body; purplish gray with yellow and blue banded dorsal (back) and anal fins; has a black caudal (tail) spine and two knifelike spines or scalpels at the base of the tail; grows to 22 in.
Habitat: shallow waters with sandy bottoms
Did you know?The yellow pectoral fins are important for identification of the pualu since it can alter its body color to almost black with a white ring around the tail. The pualu uses the two knifelike spines at the base of its tail to defend itself and to help capture prey.