Water Quality as an influence of fish populations in Strawberry Creek, Berkeley, CA Navraj Singh Padda Abstract Strawberry Creek has been very important to the Berkeley campus and the Berkeley community as a whole. Strawberry Creek has two major forks, north and south, which run through the campus and the city. Fish populations in the creek began disappearing after the turn of the 20th century due to poor water conditions and poor creek management. Since 1987 many efforts have been made to introduce fish into the creek. Currently, the south fork has an abundance of fish while the north fork has been unable to maintain a fish population. This project aims to look at whether water quality is the answer to why fish are present in one fork and not the other. Form February thru mid-April, 2002 weekly samples of pH, conductivity, turbidity, chlorine, copper, phenols and detergents were taken at five sites in each of the two forks. Weekly samples were also taken at two sites past the junction of the two forks simply known as the main branch. A Tukey-Kramer honestly significant difference test was used to detect for the difference between the sites. Data collected for all parameters was shown to not be significantly different and therefore the conclusion that water quality with respect to the collected parameters is not the reason for fish presence in the south fork and the lack of fish in the north fork in Strawberry Creek.Introduction Strawberry Creek has had a very important role in the history of the Berkeley campus of the University of California. The current site of the campus was originally chosen because of the presence of Strawberry Creek (Willey 1887). The creek represents an irreplaceable natural resource that is highly valued by both the university and the community at large (Hsieh 2001, Charbonneau 1987). The riparian corridors along the creek provide essential places for educational, recreational, social and individual activities (Charbonneau 1987). However, by turn of the 20th century, urbanization had already begun to affect the creek. Sewage and silt polluted the water (Charbonneau 1987), and the creek’s course was redirected and confined by retaining walls (Charbonneau & Resh 1999). In places, the creek was diverted into culverts (Charbonneau & Resh 1999). Strawberry Creek has two major branches, the north and south forks, and it also has a main branch that is located below the confluence of the two forks (Charbonneau 1987). Many papers in the past have focused in on Strawberry Creek and measured different variables in the water. Carlson (1971) noted high pH measurements in the creek. Frazier (1983) measured for dissolved oxygen in the water and noted that it was within the limits set by the Regional Water Quality Control Board (RWQCB). Frazier (1983) also noted that the mercury levels in the water were high and there was also a large coliform concentration. Cheung (1986) concluded that not all of the water quality parameters tested in Strawberry Creek met RWQCB standards. Cheung (1986) stated that levels of pH and dissolved oxygen met the standards but once again coliform levels were higher than allowed. Phillips (1986) noted abnormally high pH values (above 8.0) on occasion but stated that the overall chemical condition of Strawberry Creek was fairly good. Vrudhula (1988) found no build-up of heavy metals in the soil along Strawberry creek but a study by Morales (1988) found that a higher number of people or automobiles are correlated with a high concentration of heavy metals. Morales conducted his study to detect for a difference in water quality in the summer and fall sessions at campus. A relatively new study by Tudd (2001) made some startling discoveries. Tudd (2001) noted that the north fork had a mercury level of 0.77µg/L while the south fork had a mercury level of 2.5µg/L. The Environmental Protection Agency (EPA) allows a mercury level of 2µg/L for drinking water. This would suggest that Strawberry Creek is unsafe for people to use. Some studies have focused on other aspects of Strawberry Creek. Lee (2001) concluded that there werevery few high flow refuges for fish in both forks. Of the six sites (in north and south forks) studied by Lee (2001), none were found to be favorable in terms of creek habitat (Lee 2001). Yoon (2001) viewed the competition between the introduced species of fish to the crayfish (Pacifastacus leniusculus) and discovered that the crayfish prey on the young benthic fish of the creek (Yoon 2001). After the publishing of the Strawberry Creek Management Plan (Charbonneau 1987), many restoration efforts have taken place or are under way (Maranzana 2002, pers. comm.). Restoration efforts have included sewer and sanitary system repairs, bank stabilization, check dam repairs and installation, regrading, slope stabilization and revegetation (Lee 2001). These efforts have led to improved water quality and the return of several biological communities (Charbonneau & Resh 1999). The next step in the restoration process is the reintroduction of several fish species (Lee 2001). There were once at least 13 species of fish in Strawberry Creek (Lutrick 2001) but now there are only four species left (Maranzana 2002, pers. comm., Dudley 2002, pers. comm.) These species were introduced over the last 13 years. The four species of fish are the three-spined stickleback (Gasterosteus aculeatus), California roach (Hesperoleucus symmetricus), Sacramento sucker (Catostomus occidentalis), and the prickly sculpin (cottus asper) (Dudley 2002, pers. comm.) The south fork of the creek has been able to support fish while the north fork has been unable to support fish for unknown reasons (Lutrick 2001). Fish introductions to the creek have been ongoing since May 1989 when the first introductions were made (Lutrick 2001). The main branch has supported fish throughout the 1990s (Lutrick 2001). Fish survival depends upon several factors: food supply, water quality, temperature, suitable pool habitat for feeding and breeding, and cover from scouring winter flows (Charbonneau & Resh 1999). The goal of this paper is to investigate whether water quality may explain the lack of fish in the north fork by comparing water quality in the two forks and the main branch. Methods Strawberry Creek is located on the UC Berkeley campus in Alameda County, California, USA (37°52’ N; 122°15’W) (Figure 1). It runs from Strawberry canyon above the campus, down to San
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