ALGAL GROWTH IN DOG RIVER’S TRIBUTARIES


Kara Lankford,
Department of Earth Sciences, University of South Alabama, Mobile, AL 36688. E-mail: karae1980@yahoo.com.

Many streams in the Dog River watershed contain some form of algal growth. A certain amount of algae is healthy but in large amounts it can be detrimental to a stream. When algae die and begin to decompose they consume large amounts of oxygen. This leads to an oxygen-deficiency. Certain organisms thrive in an oxygen-deprived environment. These organisms release harmful substances which are toxic to aquatic life. Algae also block sunlight, harming other plants by interrupting the photosynthesis process. The main cause of excessive algae growth is the influx of nutrients. The majority of these nutrients come from non-point sources such as sewer run-off, lawn fertilizer, detergents and many others. After study sites were determined, a stream analysis revealed that algae were apparent in these particular streams, but algae were found only in small amounts. Finally, it was determined that the algal growths in these tributaries are a healthy part of the ecosystem.

Keywords: Nutrients, algae, tributaries

Introduction

The Dog River watershed is a 95 square mile drainage basin which empties into Mobile Bay. Since it drains most of Mobile it is a very important river in this area. Several tributaries or streams flowing into Dog River contain some form of algae. In layman’s terms algae are often called “pond scums,” “water mosses, “”green slime,” or even “frog spittle.” In actuality, they are any primitive, chiefly aquatic, one celled or multicellular plant that lacks true stems, roots and leaves but usually contains chlorophyll (Bold and Wynne 1978). Algae are the oldest living organisms known to man containing the coloring matter, chlorophyll (Horst, no date). They are a healthy and natural part of an ecosystem (Vymazal, 1995). In fact, many invertebrates and fish depend on algae as a food source. They also provide food for waterfowl and essential habitat for small fish, shell fish and others. However, in large amounts algae can be harmful to streams. They can interfere with photosynthesis of submerged plants by blocking sunlight causing them to die (DNR, no date). When this occurs, dissolved oxygen levels near the bottom of the stream drop. This creates an oxygen deficient environment. The problem is then compounded when organisms, which flourish in oxygen starved environments, release hydrogen sulfide and methane. These substances are toxic to fish and other aquatic life and can lead to events such as fish kills.

Nutrients are the main cause of algal growth. In mostly freshwater rivers like Dog River, phosphorus is usually the principal factor. Phosphorus is an essential nutrient for all life forms. It is the eleventh most abundant mineral in the earth’s crust (Horst, no date). Natural deposits are usually found in the form of phosphate in the mineral apatite. Phosphorus is also added to the water by human agents such as fertilizer, sewage, and detergents. Nitrogen can also trigger algal blooms but is a more common factor in salt water. There are two general sources of nutrients in our waters, natural and man made. Natural sources include nutrients that leach from soils and atmospheric deposition (Rai and Gaur, 2001). Man made sources account for much larger amounts. These include fertilizer, livestock manure, human sewage, industrial run-off and more. When these excess nutrients enter a stream, over abundant algal growth can result.

Urbanized or commercialized areas tend to produce more nutrient run-off than less urbanized area. Less urbanized communities tend to have larger yards which act as filters to the water run-off. More urbanized areas have more impermeable surfaces which cause faster run-off and have no filtering effects. Also, industries are usually in these areas which may account for some chemical run-off. Nutrient increases in Dog River come from events such as sewer leakage and spills or something as simple as lawn fertilizer or soap from washing your car.

Nitrogen and phosphorus are one of the leading causes of water quality impairment in the nation’s rivers, lakes, and estuaries. All around the coastal United States nutrient run-off is becoming a major problem by causing abundant algal growth (Patrick Center, 2000). Agricultural research scientists are concerned about the potential effects of nutrients from agriculture and other sources on the water quality of coastal estuaries such as Chesapeake Bay. These scientists conclude that excessive application of manure and fertilizer may result in run-off into waterways and ultimately into coastal water (Parker and Wright, 1999). This can stimulate “blooms” of undesirable algae. These copious amounts of algae have caused major fish kills and human health problems in the Chesapeake Bay area (Parker and Wright, 1999). Also, excessive growth of algae and aquatic plants in the Gulf of Mexico have resulted in a lifeless area known as the Dead Zone.  It was created when decomposing plants robbed the waters of life sustaining oxygen (Parker and Wright, 1999).


Research Question

Algae is apparent in some of Dog River’s tributaries, but to fully understand this growth some questions must be answered. Are certain streams more vulnerable to algae? If this question is answered then the problem streams will be detected and study sites can be determined. Also, is algae growing in excessive harmful amounts in these streams? If so, why is algae growing more abundant in these particular streams? If the causal problems are identified then measures can be taken to fix the problem and to help prevent future excessive algal growth.


Methods

Only a few tools were needed for this research so costs were kept minimal. First and foremost fellow classmates from GEO 480 reported finding no algae while monitoring their own study sites. Three study sites were used to perform this research project. The sites were found by viewing a map of the Dog River watershed and selecting streams with similar armored characteristics. One stream was a concrete armored tributary and one consisted of a mixture of concrete and some rocks covering the bottom of the channel. The other was a gabion tributary, which is basically man-made from rocks in wire cages. The streams were located in different environments where they receive different types of run-off. The location and name of each stream can be seen in Table1. There are  two sites on Eslava Creek. Viewing this stream from the air is helpful in evaluating the area surrounding the stream. These are located downstream of a more urbanized or commercialized area. The site on Spring Creek is located below a less urbanized area. These sites were selected to show if differences in watershed characteristics may affect algae growth. First of all, it had to be established if algae was present in these streams. This was done by wading in the streams searching for algae. A camera was used to take pictures of the streams where algal growth was evident. A 35mm Nikon camera was used which has a macro lens for detailed shots and 400 speed film was used for the pictures. When necessary, a digital camera was used in order for the photos to be viewed before actual developing. In the shallow portion of Eslava Creek a series of photos were taken to show how much algae covered the concrete floor. This was done by first choosing the section of the stream with the most algal coverage. Then the pictures were taken by pointing the camera straight down and walking the width of the stream while taking the photos.  This will cover about a three-foot swath. Individual assessments were made to examine stream characteristics: In other words, how the streams differ and how they are alike. Finally, samples of the algae were taken from each site in order to be examined under a microscope and identified.

Table 1. Location of study site

 

Site#1: Eslava Creek at HWY 90 East bound in the Food World Parking lot

 

Site#2: Eslava Creek at HWY 90 West bound in the Big Lots parking lot

 

Site#3: Spring Creek at HWY 90 East bound at Demetropolis Road


Results

Algae were found at all three study sites. Several different types of algae were found at two of the three sites. The site on Eslava Creek at Highway 90 East bound (Site #1) contained only one type of algae. As mentioned before a portion of this stream was analyzed by taking photos of an area of the stream. The results from this analysis show that algae covered about one quarter of the stream in this particular area. The other site on Eslava Creek at Highway 90 West bound (Site #2) had a few different species of algae. The coverage on this stream was primarily in the shallow waters along the edge of the ditch. This stream also had about one quarter algae coverage. Spring Creek (Site #3) also had several different species. Most of the algae found were green filamentous algae which almost look and even feel like hair (Prescott, 1964). They are a thread-like species. More specifically, Spirogyra was found at site number two and three.  Spirogyra is identifiable under a microscope by the possession of spiral choroplasts. It has wonderful aesthetic qualities that are only visible through a microscope (Fig. 1 ). Again, the algae were only evident along the edge of the ditch in the shallow water. Most of the algae found were benthic algae which attach to various substrates such as rocks, mud, plants or even animals (Bold and Wynne, 1985).


Discussion and Conclusions

At the time of this study there was not excessive algal growth in the tributaries examined.  The concrete stream was not more vulnerable to algal growth than the gabion stream. In these particular study sites run-off types did not make a difference as to how much algae was found in each of the streams. The more urbanized area had the same amount of algae as the less urbanized area. Water characteristics did not determine the amount of algae in these particular study areas. It is noteworthy that Spring Creek had more algal species than the other two study sites. It also had more types of other vegetation. This proves that gabion streams create a healthier stream environment as opposed to concrete stream channels. They allow for slower water flow in the stream channel and have more niches which allow plants to attach more easily. This study proves that the algae living in these streams are providing energy for other organisms. When looked at through a microscope, tiny little creatures are evident which are feeding on the algae (Fig. 2 ). These organisms along with fish or any other animals that may be living in these streams depend on this algae for food and nourishment. The algae in these tributaries are a completely natural occurrence for this ecosystem.  Although this study would have been more accurate with samples taken throughout the year, it can be used at a later date to determine if algal growth in these streams has changed over the years. This study will make it easier to assess the river’s progress or down-fall as far as water quality. If algae growth becomes a problem in these streams in the future this study will give a history of what types and amount of algae were present here in the spring of 2003. Therefore, other research projects can stem from this stream examination of algal growth in Dog River’s tributaries. It is important to point out that this study was done in April 2003 during a minimal or below average rainfall period which may affect the amount of algae present in streams

 

References Cited


Bold, Harold C. and Wynne, Michael J.  1978.  Introduction to the Algae. Prentice Hall, Inc. Englewood Cliffs, New Jersey.

 

DNR. No date. Excess Nitrogen and Phosphorus spur algal growth, deplete oxygen and kill fish.  Accessed on February 24, 2003. <www.dnr.state.md.us/forests/publications/killfish.html >

 

Horst, Kasper.  No date.  Everything about algae. Accessed on April 5, 2003 <www.dupla.com/e025.htm >

 

Parker, Henry S., Wright, Robert J. January 1999. Agriculture and Marine Environments.  Agricultural Research.  Vol.47 Issue 1, p2, 1p.

 

Patrick Center. 2000.  Assessing the Nation’s Rivers. Accessed on February 24, 2003 <http://diatom.acnatsci.org/AlgaeImage/waterline.asp >

 

Rai, L.C. and Guar, J.P.  2001.  Algal Adaptation to Environmental Stresses. Springer-VerloagBerlin Heidelberg. New York.

 

Vymazal, Jan. 1995.  Algae and Element Cycling in Wetlands. CRC Press Inc. Boca Raton, Florida.