BIO-WEST ATTACHMENT 5 FEBRUARY 19, 2014 Fountain Darter – Movement Study EFFECTS OF VEGETATION DECAY AND WATER QUALITY DETERIORATION ON FOUNTAIN DARTER MOVEMENT STUDY Literature Review and Proposed Methodology PREPARED FOR: HCP SCIENCE COMMITTEE PREPARED BY: BIO-WEST PROJECT TEAM - February 18, 2014 1 BIO-WEST ATTACHMENT 5 FEBRUARY 19, 2014 Fountain Darter – Movement Study INTRODUCTION Every summer when ambient temperatures rise, the Upper Spring Run of the Comal River experiences an excessive green algae bloom. Although this condition occurs every summer, it clearly is exasperated during lower than average flow conditions. The scenario goes like this: Summer arrives; discharge declines; water temperatures increase; sunlight is at a maximum; and green algae explodes. When it does, it blankets all aquatic vegetation within the reach. The first aquatic vegetation that is shaded and physically killed off by the algae is the resident bryophytes. Rooted macrophytes are considerably more tolerant and seem to persist for longer durations. When aquatic vegetations dies, fewer darters are typically collected in the Upper Spring Run sample reach. The question is two-fold: At what point in time is aquatic vegetation rendered unsuitable habitat and darters seek other habitat types?; and, How far will fountain darters move to find usable habitat? Benefits to HCP Ecological Model In all fountain darter population modeling conducted for the HCP to develop the flow management objectives and associated “take” quantities, an embedded assumption was if aquatic vegetation died or was removed, all darters likewise died. This is obviously not reality but sufficient data is not available to describe the movement mechanism of fountain darters. Available literature describes small body fish movement (including the fountain darter) as “relatively sedentary, moving <50 m under normal hydrological conditions” or “appear highly sedentary……under a stable hydrograph”. Relative to the fountain darter, we know this is true for normal conditions and stable hydrographs but the real data gap is what happens at the extremes, which relates to both high (floods) and low (droughts) flow conditions. Although the focus of Phase II decisions lies heavily on low-flow conditions, floods or other disturbances (e.g. recreation) that remove aquatic vegetation from the system also can significantly affect fountain darter populations should darter movement in fact be limited. Should the fountain darter continue to be a sentinel species, movement under stressed conditions is perhaps the most pressing data gap needed as input to the HCP Ecological Model to ultimately inform Phase II decisions relative to long-term biological goals and flow management objectives. LITERATURE REVIEW Movement of freshwater stream fish depends on an array of physical and environmental factors (Jackson et. al. 2001). The restricted-movement paradigm predicts that small body, resident fishes are relatively sedentary, moving <50 m under normal hydrological conditions (Gerking 1959; Gowan et al. 1994). Etheostoma, a very speciose genus composed of the smallest species of darters, conform to the predictions of the restricted-movement paradigm, being highly sedentary with 80 to 97% of individuals remaining within habitat patch of initial observation (Boschung and Nieland 1986; Labbe and Fausch 2000; Mundahl and Ingersoll 1983; Roberts and Angermeier 2007b). Among a few mobile individuals, mean distance moved is <200 m (Mundahl and Ingersoll 1983; Roberts and Angermeier 2007a). Movement among highly sedentary darters coincides with non-reproductive seasons (Mundahl and Ingersoll 1983; Scalet 1973), shifting habitat preferences as the darters grow (Labbe and Fausch 2000), and declining habitat quality (Mundahl and Ingersoll 1983; Roberts and Angermeier 2007b). Among swift water darters, a 5% area loss of riffle habitats (i.e., shallow water habitats) because of summer- time dewatering prompted Fantail Darters (E. flabellare) to move away from riffles (Roberts and Angermeier 2007b). Movement is also associated with density dependent mechanisms. Darter movement from patches has been shown to increase as resources became limited (Mundahl and Ingersoll 1983). 2 BIO-WEST ATTACHMENT 5 FEBRUARY 19, 2014 Fountain Darter – Movement Study Fountain darters, like other darters, appear highly sedentary, moving on average 10 m within a year and up to 95 m within 26 days under a stable hydrograph (Dammeyer et al. 2013). When movement occurs, fountain darters move among habitats more frequently (51%) than other darters (3 to 20%; Mundahl and Ingersoll 1983; Labbe and Fausch 2000), most often towards low growing vegetation, upstream, and during the winter and spring-summer seasons. Determining how and why fountain darters disperse throughout the Comal River system could be vital to the conservation of this species. Dammeyer et al. (2013) have offered insight into this fundamental question under a stable hydrograph, however, this study intends to further investigate movement relative to changes in habitat and temperature caused by low-flow regimes. A wealth of information on aquatic vegetation preference by the fountain darter is available through long-term biological monitoring on both the Comal and San Marcos systems. Additional, 2013 applied research efforts (BIO-WEST 2013) focused on aquatic vegetation tolerance conducted both in the laboratory and ponds at the USFWS San Marcos Aquatic Resources Center (ARC) will provide the foundation for the manipulative pond studies proposed below. A mark and recapture study is also proposed to determine how movement of fountain darters is affected by habitat and temperature changes under low flow conditions. Fountain darter mark and recapture techniques will utilize methods previously developed for darters and other small-bodied fishes, with visual implant elastomer (VIE) as the marking material. Although recapture success rate varies among movement studies (9 to 37% Belica and Rahel 2008, Dammeyer et al. 2013, Labbe and Fausch 2000, Roberts and Angermeier 2007b, Schaefer et. al. 2003, Skyfield and Grossman 2008), VIE marking has been thoroughly tested (Belica and Rahel 2008, Holt et. al. 2013, Labbe and Fausch 2000, Phillips and Fries 2009, Roberts and Angermeier 2004, Weston and Johnson 2008) and shows a high rate of retention (79 – 100%) accompanied with high survivorship (85 – 100%). Additionally, laboratory studies using darters (Phillips and Fries 2009, Roberts and Angermeier 2004) found VIE advantageous compared with other marking mediums, such as acrylic paint or photonic dye. We propose using both visual (re-sight) and physical (dipnet, recapture) methods for relocating fountain darters due to their habitat affinity (i.e. benthic fish occupying areas of dense vegetation) (Alexander and Phillips 2012, Linam et. al. 1993), characteristics of the study reach, and successes/suggestions of previous studies (Belica and Rahel 2008, Dammeyer et al. 2013, Holt et. al. 2013, Jordan et al 2008, Labbe and Fausch 2000, Skyfield and Grossman 2008). The proposed field mark recapture study will be augmented by manipulative trials in an experimental pond to address the effects of specific factors on fountain darter movement. PROPOSED METHODS Fountain Darter Movement Manipulative Pond Studies An experimental pond at the ARC will be used as a study area for a series of experiments investigating the movement of fountain darters. Initial small scale trials will be used to refine experimental design and methods prior to commencement of the formal experiments. The initial experiments will investigate the use of vegetated vs. non-vegetated habitat patches by fountain darters. Vegetated patches will consist of specially designed Mobile Underwater Plant Propagation Trays (MUPPTS) planted with Ludwigia repens. The vegetation will be established in the pond prior to the beginning of experiments to allow for colonization of the vegetated patches by invertebrates to provide a food source representative of a natural system. Prior to initiation of experimental trials, all vegetation patches will be cropped to the same height to ensure homogeneity among patches. Vegetated patches will be arranged interspersed with equally-sized non-vegetated patches. Approximately one hundred fifty experimental darters will be housed in a holding tank at the ARC for use in these experiments. Darters will be allowed to “rest” in the holding tank between experimental trials such that the same individuals 3 BIO-WEST ATTACHMENT 5 FEBRUARY 19, 2014 Fountain Darter – Movement Study are not used in successive trials, but are rotated through experiments. All darters will be marked with visible implant elastomer (VIE, Northwest Marine Technology, Shaw Island, WA) using colors that fluoresce in a specially developed light designed by the manufacturer. It is anticipated that this will allow visual census of darters during the experiment. Fifty darters will be used for each two-week trial, with two trials per experiment. Darters will be introduced into the central vegetated patch, and all patches will be observed for darters twice weekly via snorkeling. Successive experiments are contingent upon the outcome of the first. Assuming that darters distribute themselves predominantly among vegetated patches only, the next experiment will focus on the relationship between inter-patch distances and darter movement. An array of vegetated patches will be placed such that all patches are different distances from a central patch in which