Spatial effect on ecology and behavior of 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 (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 . 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

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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)

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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 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.

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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. 383 roach the seven sites consisting of three upstream were caught downstream, and 317 were and two downstream locations. Fish caught upstream. On average, California randomly chosen from the catch were roaches were approximately 1 cm bigger observed in a 10.5 gallon container filled downstream from the riffle compared to with 5.5 gallons of water. Inside the upstream (n=34, F=7.12, p=0.016, SE=0.14, container, a rock with approximately 100% SD=0.39; Figure 2). There was a positive algal cover was placed to observe roach correlation between fish abundance and feeding. Fish were observed for 10 minutes percent algal cover (n=34, R2=0.37, and notes where taken on their shelter p=0.001; Figure 3). There was a negative seeking and feeding behavior. This was effect of the velocity of the river on the done in five different groups of two, four, average size of the California roach (n=18, six, eight, and ten fish. Five trials were R2=0.36, p=0.005; Figure 4). Furthermore, completed for groups two, four, six, and as velocity of the river increased, the eight respectively, while 17 trials were done abundance of roach decreased (n=34, for groups of 10. After each trial, the fish R2=0.14, p=0.0289). California roach did not under observation were measured and feed in groups fewer than 10 (n=39, released. x2=13.39, p = 0.02). Fish caught upstream the riffle sought shelter 100% of the time, compared to approximately 70% for downstream fish (n=39, x2=6.97, p=0.008; Figure 5).

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Figure 2. California roaches are bigger downstream Figure 4. In faster waters, there are smaller fish. the riffle. Within the Eel River of Northern California There is a negative relationship between the size of there were bigger sizes of the California roach California roaches and water velocity (n=18, R2= downstream the riffle when compared to upstream 0.36, p = 0.005) the riffle. (n= 34, f ratio= 7.1238, p = 0.0168)

Figure 5. California roaches seek shelter more often Figure 3. More California roach present with higher upstream riffles. Observational analysis revealed algal cover. There was a positive relationship that California roach exhibit shelter seeking between the abundance of California roaches and behaviors upstream more than downstream. (n = 39, 2 amount of algal cover. (n = 34, p=.0001, R2= 0.37) x = 6.97, p = 0.008). DISCUSSION population size, with more feeding in groups of ten. Additionally, shelter seeking We found that roaches are variable in behavior was found to be more common population and body size across upstream riffles. These results suggest that microhabitats of a river, being more California roach variation and distribution abundant in shallow low flow areas, and can be attributed to specific river structure, larger downstream riffles. Furthermore, and it is possible that these traits may vary their feeding behavior varies depending on across different river characteristics.

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We hypothesized that California roach cause stress on the fish’s body which can be would be more abundant downstream. Our fatal (Hockley et al. 2014). In addition, it is study found that roaches were greater in possible that roaches upstream riffles seek abundance and larger downstream. This shelter as a way to stabilize their body from result can be attributed to habitat a hydrodynamic disturbance (Webb 2004; preference. California roach prefer low Liao 2007). The seasonal patterns that stream flow and smaller pools (Marchetti affect the river also affect the California and Moyle 2001). In this study, most fish roach. This study was completed during a were caught downstream the riffle where low flow season; however, in a high flow these small low stream flow pools existed. season, it is possible the fish may seek more When fish are in these preferred habitats, shelter up or downstream the riffles. Future their survival and food rate intakes increase studies should look at the different seasonal (Roussel and Bardonnet 1997). From this, variations of the river. bigger and greater abundance of Roaches upstream from the riffle were populations of roaches can be anticipated. found to seek shelter under rocks 100% of In ideal conditions it is easier for the the time. Fish found upstream a riffle will California roach to forage for food sources naturally seek protection because they like the predominant algae in the Eel river, occupy an area with high risk of being Cladophora glomerata. This could explain carried downstream (Aadland 2011). the bigger size of the fish downstream of Upstream a riffle, water velocity flows at a the riffle. greater rate which also leads to turbulence The positive correlation between percent (Liao 2007). In order to avoid these factors algal cover and California roach abundance they will naturally seek protection as suggests the fish are most present where observed in our behavioral study. Fish in their primary food source is. This parallels a these locations seemed to display previous study showing that as drift algae behavioral plasticity as a response to their biomass, the primary refuge for code goby environmental conditions (Bhat et al 2015). (Gobiosoma robustum) and gulf pipefish In addition, studies have also shown that (Syngnathus scovelli), increases, fish during a low rainfall winter season, the fish abundance does as well (Kulczycki et al. will seek protection at a greater rate during 1981). These results suggest that fish summer due to the increased flow rate depend on algal cover for various factors. (Power et al 2008). Therefore, a future On the Eel river, the bloom of Cladophora study to evaluate these effects could be glomerata provides a food source for both done to observe behavioral changes in adult and fry of California roach (Power response to different seasons of water flow. 1990). It is possible that this species serves California roach begin to feed on an algal as a buffer for algal bloom during spring and covered rock in groups of 10, but did not summer. feed at all from groups two through eight. California roach abundance and size This suggests that this species of fish decrease as the velocity of the river primarily feed more in groups. Our results increases. Fast-moving waters cause align with the idea that smaller fish lower in increase in turbulence, which change the food web tend to associate themselves pressure and velocity of the river. This can in schools for protection (Hager and

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Helfman 1991). A previous study found that ACKNOWLEDGMENTS juvenile sockeye salmon (Oncorhynchus nerka) school primarily in the afternoon, This work was performed at the and leave to feed, individually, before dawn University of California’s Angelo Coast (Eggers 1978). Although this contradicts the Range Reserve, doi:10.21973/N3R94R. We roaches feeding behavior, the juvenile would like to thank the University of salmon are not fully developed, while the California Angelo Coast Range Reserve. We roaches have completed their growth. This would also thank Tim Miller, Krikor raises the question as to how different fish Andonia, Ana Miller-Ter Kuile, and our species that vary in developmental growth cohort for their support and contribution to behave relative to their life cycle. our research. Due to the abundance of the California roach in the Eel River, its overall effect on REFERENCES its environment is of great concern. This Aadland, L. 1993. Stream habitat types: Their fish study has shown how the low flow water assemblages and relationship to flow. North levels of spring affect the biotic and abiotic American Journal of Fisheries Management 13: factors that impact this species. Although 790–806. patterns were established in their Baumsteiger, J., A. Kinziger, and A. Aguilar. 2012. Life distribution, physiology, and behavior, more history and biogeographic diversification of an research must be done following low endemic Western North American freshwater fish rainfall winter seasons along the Eel River. clade using a comparative species tree approach. Small fish such as the California roach Molecular phylogenetics and evolution 65:940– prefer environments of low flow pools and 952. rich food abundance. Variation in its habitat Bhat, A., Greulich, M.M. and Martins, E.P. 2015. may cause trophic cascade, and could alter Behavioral plasticity in response to environmental the food web in this system. manipulation among zebrafish (Danio rerio) Work has been done on the California populations. Plos One 10: 1–13. roaches contribution to the food web of the Brown, L. R., Moyle, P. B., Bennett, W. A., and B. D. Eel River (Power 1990), but this study is a Quelvog. 1992. Implications of morphological next step towards looking at how species in variation among populations of California roach the food web interact in microhabitats. Lavinia symmetricus () for conservation River food webs are dynamic. Seasonal policy. Biological Conservation. 62:1–10. variations alter the rivers flow rate and Cech, J. J., S. J. Mitchell, D. T. Castleberry, and M. depth, which could change the food web in McEnroe. 1990. Distribution of California stream this system. This study aimed to understand : influence of environmental temperature such variation, specifically its effect on the and hypoxia Environmental Biology Fish 29:95– California roach in the spring. 105. Understanding the spatial differences in Chovanec A., H. Rudolf, and S. Fritz. 2003. Trace such ecosystems is important for further metals and other contaminants in the development in food webs. environment. Elsevier 6:639–676.

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