Spatial effect on ecology and behavior of Lavinia symmetricus in a riparian habitat Brenna Lizbeth Bolanos1, Clarisa Areli Martinez2, Brandon Alexander Quintana3, Kevin Salgado4 1University of California, Merced; 2University of California, Irvine; 3University of California, Santa Barbara; 4University of California, Riverside ABSTRACT Fish are an essential link to the dynamiC of their environment. They are able to serve as bioindiCators of a rivers health, and when abundant Can help understand a rivers eCosystem. The California roach (Lavinia symmetricus) is a widespread speCies found in high densities in various waterways. In the Eel River, heavy rain winters Cause algal blooms and water levels to drop during the spring and summer, resulting in possible CompliCations for the fish. This Causes eCologiCal ConCern towards the speCies due to their ability to reduCe algae and be a food sourCe in the rivers. This study aimed to look at how a high preCipitation winter affeCts the miCrohabitat distribution, population eCology, and behavior of the California roach during the spring. Fish were Caught and measured at seven sites along the river. Algal Cover and veloCity of the river were also noted at these loCations. Additionally, an observational study was ConduCted to examine the behavior of the fish. There was a positive Correlation between algal Cover and California roach abundanCe. California roach were also more abundant and larger downstream riffles. As veloCity of the water inCreased, fish abundanCe inCreased, but size deCreased. California roach fed more often in groups of 10, and sought shelter upstream riffles. These results provide distributional and behavioral insight on a speCies eCologiCally important to the Eel River, and add to the food web dynamiC of the eCosystem. Keywords: Lavinia symmetricus, Eel River, miCrohabitat, behavior plastiCity, riffle INTRODUCTION been found to suppress growing populations of zooplankton and indireCtly SpeCies of fish in abundanCe are essential benefit miCrozooplankton in decline (Thorp to the dynamiC funCtion of river and Casper 2003). In addition, fish eCosystems. Fish make up a large Contribute to river nutrient CyCles through proportion of mass in many river the dispersal of nutrients stored in their eCosystems, and their eCologiCal niChes may tissue as they travel up and down streams not be filled by other speCies (Mazumder et (McIntyre et al 2008). These studies suggest al. 2016). For example, in the St. LawrenCe that fish fauna distributions and River, yellow perCh (Perca flavescens) have CEC Research | https://doi.org/10.21973/N3N37W Spring 2019 1/8 abundanCes are able to serve as biomass in springs and summers following bioindiCators for overall river health winters with heavy rainfall (Power et al. 2008). (Chovaene et al. 2003). TypiCally, Additionally, the water level and flow rate bioindiCators have been used to inform of the river deCrease, affeCting the river management and Conservation; abundanCe of riffles found along the Eel however, the relative abundanCe and River. These riffles form small pools where distribution of fish Can serve as a the California roach prefer to stay. bioindiCator to examine the role of river Furthermore, riffles have been shown to miCrohabitats. affeCt the distribution of small fish (Jonsson HistoriCally, researCh on the role of fish in 1991). These findings raise questions freshwater systems has foCused more on regarding how these biotiC and abiotiC the effeCts of large fish speCies. However, variables influenCe the California roach. smaller fish Can also have important The California roach is an abundant impacts in these systems. For example, the speCies in the Eel River and serves an presenCe of small but abundant sCulpin important role in its food web. The seasonal proved important to their eCologiCal role variations that affeCt their primary food within their respeCtive habitats sourCe and the water level of the Eel River (Baumsteiger 2012). SCulpin Control other raise eCologiCal ConCern for the roach in this fish populations by preying on their eggs area. Additionally, little researCh has been and serve as a food sourCe for bigger fish, done on the behaviors of California roach, mammals, and birds (Baumsteiger 2012). whiCh Could serve as a bridge for trophiC One suCh important small fish is the interactions and Conservation. Therefore, California roach. This fish is Common and we studied how the California roach native to Central and Northern California, responds to algal Cover in small pools ranging from the San Joaquin to the Eel formed by upstream and downstream River (Brown et al. 1991). These fish typically riffles, as well as how these riffles affeCt range from 2 to 10 Cm and are resilient to them. Points of interest were roach intermittent waters. Roaches are stress miCrohabitat distribution, population tolerant and are able to survive in low levels of eCology, and behavior along the Eel river. dissolved oxygen and Can be Capable of SpeCifiCally, we prediCted that: withstanding a wide range of temperatures (CeCh et al. 1990). Although the California 1) more fish will be present and average roach is a small native fish, this species may roach size will inCrease downstream impaCt its environment in a big way. riffles. Areas downstream riffles form Studies on the California roach have pools with lower flow rates, examined biotiC and abiotiC factors that providing an ideal habitat for affeCt them. ResearCh done on the Eel River California roach (MarChetti and in California has shown that the California Moyle 2001) roach reduCes the presenCe of filamentous 2) fish will be more abundant in areas green algae, while their absenCe inCreases of high algal Cover. California roach it. (Power 1990). The predominant alga of feed on algae, and small fish speCies the river, Cladophora glomerata, a primary favor areas with an abundanCe in food sourCe for roach, reaches peak food. (KulCzyCki et al 1981) CEC Research | https://doi.org/10.21973/N3N37W Spring 2019 2/8 3) inCreased water veloCity will deCrease roach abundanCe and average size. Studies have found that small fish speCies are negatively Correlated with high river veloCity, whiCh Could affeCt their physiology and distribution (Webb 2004; Liao 2007) 4) California roach will feed more often in groups due to sChooling. This has been shown to be a proteCtion meChanism that may allow fish to initiate feeding (Hager and Helfman 1991) 5) fish upstream riffles will seek shelter Figure 1. Fish collection sites. The seven ColleCtion more often. Upstream riffles have sites (orange circles) are located along the Eel River higher veloCity flow and water in Northern California. Traps were plaCed at eaCh of turbulenCe that may harm small fish these seven loCations to Catch California roaChes. speCies (Aadland 2011). 2.2 Experimental Design: Roach Population METHODS Structure 2.1 Natural History of Study System To test the effeCt of algal Cover and riffles on California roach, we ConduCted this ResearCh was ConduCted in Spring, May 9- study at seven sites (Figure 1) along the Eel 12, 2019, at the Angelo Coast Range river where riffles were present. At site one, Reserve (39.739167°, -123.630833°) in three trials were ConduCted, two at site MendoCino County, California along the two, four at site three, three at site four, South Fork of the Eel River (Figure 1). The three at site five, and one at sites six and study area is Characterized by a seven totaling 34 trials. The loCations within Mediterranean Climate with wet, Cool these sites Consisted of small, low river flow winters and dry, warm summers. Average pools upstream and downstream from preCipitation is 215.6 cm per year. Due to riffles. At each of the riffles, one 42x23 Cm limited human impact, the Angelo Coast baited minnow trap was placed 10 m before Range Reserve allows for researCh to be and after the riffle, approximately one done under pristine water Conditions meter deep. Traps were baited with lunCh (Howard et al. 2004), making it an ideal meat/sausages and left for approximately study site for aquatiC speCies, suCh as the 24 hours. Upon retrieval, total amount of California roach. roaches were noted, 10 were randomly measured to estimate average fish size. CEC Research | https://doi.org/10.21973/N3N37W Spring 2019 3/8 2.3 Experimental Design: Microhabitat 2.5 Statistical Analysis Abiotic Factors All ColleCted data was analyzed using JMP At each of the seven sites, algal Cover and statistiCal software v13. We ran a t-test to veloCity of the river were measured to test Compare average California roach size their effeCt on the California roach. Before before and after riffles at our 7 study sites, and after the riffles, 10 m point transeCts for a total of 34 repliCates. Linear were taken to measure perCent algal Cover regressions were used to look at the effeCt from the trap to the riffle. This was done by of algal Cover on fish abundanCe, and the visually estimating the algal Cover on a roCk effeCt of veloCity of the river on the at every meter. To measure the veloCity of abundanCe and size of the California roach the water, a ping-pong ball was placed in across the 7 sites. Chi-squared test were ran the water 3 m before the trap. The distanCe to evaluate the variation of feeding and traveled and time it took the ball to reach shelter seeking behavior on group sizes of the trap was divided to obtain veloCity of two, four, six, eight, and ten fish. the water in meters per seCond. RESULTS 2.4 Experimental Design: Roach Feeding and Protection Behavior In total, 700 California roaches were Caught across the seven sites. 37, 126, 475, In order to test their behavior, California 55, 7, 0, and 0 fish were Caught for sites one roach observations were made at three of through seven, respeCtively.