Abstract

Endangered woundfin Plagopterus argentissimus embryos and larvae were exposed to artificial ultraviolet-B (UV-B) radiation to directly examine the effects on mortality. The experiment was part of a project assisting the Virgin River Resource Management and Recovery Program's efforts to increase hatchery production of this endangered fish. The UV-B radiation used in this experiment was administered in treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25% of the ambient irradiance levels documented in outdoor tanks and living streams at Bubbling Ponds State Fish Hatchery, in Arizona. Embryos and larvae were exposed for 14.5 h followed by 9.5 h of darkness, in correspondence with the daylight hours at Bubbling Ponds. No embryos survived UV-B treatments; mortality among control (UV-B–free) treatments varied (5–100%) among females, indicating that there may be important parental effects that influence embryo mortality. Larval mortality was also 100% for individuals exposed to any of the three UV-B treatments. In contrast to embryo trials, larval mortality in UV-B–free treatments approached 20% for 2-d-old larvae. These experiments provide evidence that woundfin embryos and larvae are sensitive to even low levels of UV-B when exposed for 14.5 h. Susceptibility of larvae to UV-B also appears to be a function of age at exposure, with older larvae exhibiting significantly lower levels of mortality during the initial days of exposure. Experiments with UV-B mitigation strategies indicated that shade cloth, Aquashade®, and elevated dissolved organic carbon can aid in the attenuation of UV-B, and these strategies may assist hatchery managers in implementing UV-B mitigation measures during periods when woundfin are most susceptible.

Introduction

The steady and significant depletion of stratospheric ozone has produced a measurable increase in the levels of ultraviolet-B (UV-B; 280–320 nm) radiation entering the earth's freshwater habitats (Cracknell and Varotsos 2009). Measurements of elevated UV-B have been accompanied by studies documenting the deleterious effects of UV-B on susceptible life stages of aquatic organisms (Häder et al. 1995; Bancroft et al. 2007; Dong et al. 2007; Romansic et al. 2009; Calfee et al. 2010). Studies conducted with fish embryos and young larvae show increased mortality and impaired development as a result of exposure to ambient and elevated UV-B (Hunter et al. 1979; Kouwenberg et al. 1999; Häkkinen et al. 2002; Weigand et al. 2004; Dong et al. 2007), and combined, these factors may limit recruitment to adult populations (Béland et al. 1999). For example, recent evidence shows that Atlantic cod Gadus morhua embryos are particularly susceptible to UV-B radiation during gastrulation (Kouwenberg et al. 1999).

The principal effect of UV-B on fish and other aquatic organisms is the formation of pyrimidine dimers that manifest as lesions and alter the structure of DNA (Douki 2010). Specifically, pyrimidine dimers inhibit replication and transcription of the DNA (Buma et al. 2003) and can lead to deformities and/or increased mortality (Bancroft et al. 2007). Because of the harmful and potentially lethal effects of UV-B, many organisms have physiological strategies that assist in repairing or preventing UV-B induced damage (Häkkinen et al. 2002; Wiegand et al. 2004; Bancroft et al. 2007) or have altered activity patterns (e.g., seeking UV-B–free refugia or modifying periods of activity) to minimize exposure to elevated UV-B (Ylönen et al. 2004; Garcia et al. 2009). Despite the documented effects of UV-B, studies to date have been limited to a relatively small number of aquatic vertebrates.

The effects of UV-B on woundfin Plagopterus argentissimus are unknown. The woundfin is native to the lower Colorado River basin, but the combined effects of habitat loss, flow alteration, and competition with invasive species have reduced the woundfin's distribution to a fraction of its historic range (USFWS 1994). Woundfin are now restricted to reaches of the mainstem Virgin River (USFWS 1994) and were listed as endangered in 1970 (USFWS 1970), a designation that provides protection under the Endangered Species Act (ESA 1973). Recovery efforts for the federally endangered (ESA 1973) woundfin include captive rearing at three facilities: Southwestern Native Aquatic Resources and Recovery Center, New Mexico; Bubbling Ponds State Fish Hatchery (Bubbling Ponds), Arizona; and Wahweap State Fish Hatchery, Utah. The principal goal of the Virgin River Resource Management and Recovery Program (Recovery Program) is to successfully rear woundfin at these facilities for repatriation to its former range. The Recovery Program has a restocking program currently underway that calls for as many as 100,000 10-mo-old woundfin to be produced annually (S. Meismer, Virgin River Resource Management and Recovery Program, personal communication).

The culture practices and conditions for rearing woundfin at the production facilities increase the likelihood that embryos and larvae are exposed to UV-B. The production of woundfin at the aforementioned facilities is done through the use of outdoor ponds and streams. These habitats lack the physical complexity of natural habitats and have low concentrations of dissolved organic carbon (DOC); organic debris and DOC aid in blocking or attenuating UV-B (Williamson et al. 1996; Bukaveckas and Robbins-Forbes 2000). At Bubbling Ponds, few viable woundfin larvae have been found in outdoor ponds and streams following the spawning season. Given the reported effects of UV-B on developing embryos and larvae, we hypothesized that UV-B may contribute to poor survival at the conservation propagation facilities. To test this hypothesis, we examined how varying levels of UV-B affect captive-reared woundfin embryo mortality immediately following fertilization and larval mortality at different ages posthatch. Ambient UV-B radiation at Bubbling Ponds during the woundfin spawning season was documented in 2011, and we used these ambient levels as a guide for our study. Accordingly, three UV-B irradiance levels were included to better understand what UV-B levels are lethal to woundfin. Additionally, we also explored the use of three UV-B mitigation techniques that could be used to reduce incoming UV-B levels on captive reared woundfin.

Materials and Methods

Ultraviolet-B exposure chamber

We established the UV-B treatments using a four-chamber exposure system. This system was composed of an aluminum water bath (35.5 cm × 26.2 cm × 121.9 cm) separated into four discrete chambers using sheets of 2-mm fiberglass-reinforced plastic that were secured to the water bath with a silicone sealant. The system was located in a quarantine room at Bozeman Fish Technology Center, and therefore, the system had a dedicated water system. Water flowed through the system at a rate of 7.5 L/min and the temperature averaged 21.1°C (range: 18.5 to 24.5°C) for all trials. At the initiation of the experiments, source water pH was 8.7, NO3-N concentration was 0.01 mg/L, NH3-N concentration was below detection levels, and the DOC was 6.9 mg/L. Temperature loggers (iButton, Maxim, Sunnyvale, CA) were also used to document water temperatures within each of the four exposure chambers.

In 2011, we designed treatments to simulate ambient UV-B levels (approximately 0.060 mW/cm2) measured at Bubbling Ponds facility during spawning. We took measurements of UV-B at a depth of 60 cm, where embryos have been detected in previous years. Treatment levels in this experiment were 0.060, 0.030, 0.015, and 0.000 mW/cm2, designed to simulate 100, 50, 25, and 0%, respectively, of the ambient UV-B levels documented at Bubbling Ponds. We used a UV-B–free treatment (0% of ambient UV-B) as a control in all trials. We made UV-B measurements using a 2100 PMA (personal measuring assistant) meter and a 2102 UV-B detector (Solar Light, Philadelphia, PA).

The three different UV-B irradiance levels were achieved by suspending one UV-B-313-EL light bulb (Q-Lab, Cleveland, OH) and one Verilux Instant Sun Full Spectrum model F40T12SUN light bulb (Verilux Inc., Stamford, CT) in a common ballast established at different distances from test embryos or larvae held in incubation cups. The UV-B-313-EL bulbs produce a small level of detrimental UV-C (< 280 nm) radiation that is not present in natural systems because stratospheric ozone absorbs UV-C before it reaches the earth's surface (Lepre et al. 1998). Pyrex glass dishes have been shown to be an effective filter of UV-C radiation (Lepre et al. 1998), and we used Pyrex dishes in follow-up trials (completed in 2012) to confirm that mortality observed in 2011 was not UV-C related.

We constructed incubation cups using a 5-cm-diameter polyvinyl chloride coupler with a nylon screen (500 µm) inserted 3.8 cm from the bottom of the coupler. The control chamber consisted of two Verilux full-spectrum light bulbs suspended at a distance equal to the 50% UV-B treatment. We randomized the order of treatments between trials by reestablishing unique irradiance levels in each chamber. We set the photoperiod at 14.5 h light and 9.5 h dark, which was maintained with an automatic timer. This photoperiod corresponded to the average number of daylight hours during spawning season at the Bubbling Ponds rearing facility. We documented variation in irradiance levels for the entire 14.5-h irradiance period once for each of the four UV-B treatments.

For both embryo and larval trials, we checked woundfin daily for mortality until there were no embryos or larvae remaining in the treatment chambers or until the trial was over. We removed incubation cups containing embryos from the system (embryos were maintained in water during transport and assessment) and checked for mortalities under a dissecting microscope. We conducted observations of mortality for larvae during larval trials by shining a light-emitting diode light with a red filter over the tops of the cups and documenting the number dead. We recorded the number of mortalities for each incubation cup, and removed nonviable embryos and larvae to eliminate mortality caused by fungus spreading from nonviable woundfin to viable woundfin resulting in non–UV-B related mortality.

Spawning

Woundfin embryos and larvae in both 2011 and 2012 were progeny from the 2008 and 2009 year class (origin: Southwestern Native Aquatic Resources and Recovery Center) maintained in indoor tanks at the Bozeman Fish Technology Center. Before the start of each embryo trial, we hormonally injected 30 fish (20 females and 10 males) with 20 µg/g carp pituitary extract (Argent Chemical Laboratories, Redmond, WA). Twenty-four hours postinjection we strip-spawned the fish. The eggs were immediately fertilized, and fertilization success was assessed (presence of first cleavage) within 30 min.

Embryo trials

We conducted embryo trials using multiple females and approximately 20 embryos from each female per UV-B treatment. To avoid density-related mortality, we split embryos from each female between two incubation cups (approximately 10 embryos per cup; see Supplemental Material, Figures S1, S2, S3, S4, S5 and S6) for each treatment. For all trials, we attempted to include embryos from three females. When successful (trials 3, 4, and 5), this resulted in a total of 240 embryos per trial: 20 embryos per female × three females × three UV-B treatments and one control treatment. We summarized mortality results by female by pooling the mortality information across both cups. For trials 1, 2, and 6, we were only able to successfully spawn two females; inclusion of only two females in these trials resulted in the use of 160 embryos (20 embryos per females × two females × two UV-B treatments and two control treatments).

For embryo trials 1 and 2 in 2011 and trial 6, conducted in 2012, we ran the experiment for 5 d. In trials 3, 4, and 5 in 2011, we carried out the experiments for 9, 11, and 10 d, respectively. We chose to use a more protracted observation period in later trials to more carefully assess mortality of control embryos. Because we saw no mortality in control embryos past 5 d, all data are reported up to 5 d. The UV-C was not blocked in trials 1–5 but was for trial 6.

Trial 6, which was conducted in 2012, included Pyrex dishes filtering out UV-C radiation. A total of 160 embryos were collected from two different females, and 10 embryos were placed into each of the 16 incubation cups. This resulted in fewer incubation cups per exposure chamber than in the 2011 trials but we were constrained by a limited number of embryos available in 2012.

Larval trials

We placed embryos not used for embryo trials in 10-cm incubation jars and allowed them to hatch. After hatching, we put larvae into 61-cm-diameter fiberglass tanks with 20 cm of water. The tanks contained larvae from multiple females and therefore contained a mixture of progeny. In trials 1 and 2, we exposed larvae to UV-B 2 d after hatching. For trials 3, 4, and 5, exposed larvae were 5–6 d, 27–30 d, and 41–44 d posthatch, respectively. For the larval trials, we lowered water levels to 5.4 cm inside the exposure chambers to prevent larvae from swimming out of the incubation cups. Because of the reduction in water levels, we were unable to produce a treatment that was 25% of the ambient UV-B levels documented at Bubbling Ponds. Treatment levels for larval trials were limited to 100, 50, and 0% of the ambient intensity. With the exception of trial 1, we used three incubation cups per exposure chamber for larval trials; this resulted in a total of nine cups and 45 larvae per trial (five larvae per cup × three cups per treatment × two UV-B treatments and one control treatment). In trial 1, a limited number of larvae available restricted the number of incubation cups to one per treatment (five larvae per cup × one cup per treatment × two UV-B treatments and one control treatment).

In the final two larval trials (trials 4 and 5), we produced a second 0% treatment using multiple sheets of acetate (nine sheets) to shield the larvae from UV-B emitted from the combination of UV-B-313-EL and full-spectrum light bulbs. This 0% UV-B control contrasted with the other 0% UV-B irradiance produced using two full-spectrum bulbs. Because of this additional treatment, these final two 2011 larval trials required an additional three incubation cups and an expanded total of 60 larvae (five larvae per cup × three cups per treatment × two UV-B treatments and two control treatments). These trials also allowed us to compare mortality among the two different 0% UV-B treatments and assess whether bulb type (full-spectrum vs. UV-B bulbs) contributed to the results in our 0% UV-B treatments. We used Pyrex dishes to shield UV-C only in the 2012 embryo trial (trial 6). We did not use Pyrex dishes in any of the larval trials.

Ultraviolet-B mitigation strategies

We examined the ability of three different UV-B mitigation strategies: 90% black knitted shade cloth, Aquashade® aquatic dye, and DOC (introduced as sucrose [C12H22O11]) to attenuate UV-B. We briefly describe the experiments for each strategy below. All experiments were conducted outside in 3.5-m3 tanks (external dimensions 1.2 m × 2.4 m × 1.2 m) that were filled to a depth of 60 cm to mimic water depths present at Bubbling Ponds rearing facility and using source waters described above.

Aquashade

Prior to introduction of Aquashade, we took UV-B measurements in untreated source waters at the surface and at a depth of 60 cm in order to obtain a ratio between the two measurements. We then introduced Aquashade in aliquots that would increase the concentration of the dye in the tank by 1 mg/L. After its introduction, we mixed Aquashade for 5 min and allowed it to dilute evenly for approximately 1 h. After 1 h, we took UV-B measurements at a depth of 60 cm and at the surface. We used the surface reading to document any possible changes in ambient UV-B that occurred over the course of 1 h. By using the surface UV-B measurement and the ratio of UV-B absorbed in 60 cm of untreated water, we were able to calculate UV-B levels at a 60-cm depth in untreated water. This step was important because we conducted the experiments outside and UV-B levels were subject to natural fluctuations. After we recorded readings for each Aquashade concentration, we raised the concentration 1 mg/L, and repeated the steps until we reached a final concentration of 9 mg/L. We repeated this experiment in triplicate for concentrations ranging from 1 to 4 mg/L and only once for the remaining concentrations up to 9 mg/L.

Dissolved organic carbon

Natural levels of DOC in aquatic environments lead to the attenuation of UV-B in freshwater (Morris et al. 1995; Williamson et al. 1996). We introduced sucrose to manipulate DOC in source waters. Our approach for measuring and estimating UV-B attenuation and increasing DOC concentrations followed the methods described for treatments of Aquashade. Although sucrose alone does not reflect the natural complexity of DOC in the environment, it provided an opportunity for us to examine how the intentional manipulation of DOC may influence UV-B levels in outdoor rearing facilities. We manipulated DOC levels increasing concentrations in DOC between background levels in source water to background + 6.5 mg/L DOC as sucrose. We repeated the entire experiment twice.

Shade cloth

We characterized the reduction in UV-B provided by 90% black knitted shade cloth (EnviroCept Greenhouse & Supply, Benton City, WA). We floated shade cloth at the water surface and held it in place during measurements. As described previously, we completed measurements at a depth of 60 cm and at the surface both before and after the treatments were imposed to assist in documenting natural changes in UV-B in addition to quantifying the treatment effect.

Data analysis

We used fixed effect one-way analysis of variance models to characterize differences in the mortality of embryos or larvae among UV-B treatments for each trial and across trials to examine differences in mortality for individual exposure days. In the embryo trials, we used females as the unit of replication. In the larval trials, mixed progeny prevented us from tracking larvae by individual, and we therefore used the incubation cups as the unit of replication. For some trials, limited sample sizes (larval trial 1 and embryo trials 1, 2, and 6) or lack of within group variation (larval trials 3–5) prevented us from using inferential statistics. In these instances, we used descriptive statistics to summarize mortality by treatment. We arcsine square-root transformed all percentage data prior to analysis (French and Lindley 2000). We used correlation and regression analysis to examine the relationship between larval age and mortality during each 24-h exposure period. Finally, we used a nonlinear exponential decay function to model the attenuation of UV-B with different concentrations of Aquashade and DOC. We analyzed embryo and larval mortality data using Microsoft Excel 2007 software (Microsoft Corporation, Redmond, WA).

Results

Environmental conditions

Water temperatures averaged 21.1°C (range: 18.5 to 24.5°C) across treatments, and the mean measured water temperature differed by less than 0.2°C among the four exposure chambers (21.2, 21.0, 21.1, and 21.0°C). More than 90% of the 535 total readings from each chamber were ≤ 22°C. Time series plots of experimental chamber temperatures showed no indication of a UV-B treatment effect; however, these plots did indicate that there was variation in source water temperature over the course of the 10 trials. Although this variation was measurable, it would have been experienced by all organisms in a trial regardless of the UV-B treatment.

The 100% UV-B treatment had a mean (± 1 SD) irradiance of 0.0563 ± 0.0006 mW/cm2 (range 0.0541–0.0583 mW/cm2), which was slightly lower than our target treatment of 0.0600 mW/cm2. The 50 and 25% treatments had mean irradiance levels of 0.0297 ± 0.0006 mW/cm2 and 0.0164 ± 0.0003 mW/cm2, respectively. Although some variation in irradiance levels were documented over the 14.5-h dosing period, the coefficients of variation for the mean irradiance levels were low and similar across treatments (Figure 1); coefficients of variation were 1.64 (25%), 2.02 (50%), and 1.01 (100% UV-B), respectively.

Figure 1.

Irradiance levels summarized over the 14.5-h irradiance period for each of the ultraviolet-B (UV-B) radiation treatment levels to which woundfin Plagopterus argentissimus were exposed. The treatment levels were 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. The control is 0% UV-B. We exposed woundfin larvae and embryos to UV-B radiation in a controlled experimental exposure chamber at the Bozeman Fish Technology Center in Bozeman, Montana, in June and July of 2011 and 2012.

Figure 1.

Irradiance levels summarized over the 14.5-h irradiance period for each of the ultraviolet-B (UV-B) radiation treatment levels to which woundfin Plagopterus argentissimus were exposed. The treatment levels were 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. The control is 0% UV-B. We exposed woundfin larvae and embryos to UV-B radiation in a controlled experimental exposure chamber at the Bozeman Fish Technology Center in Bozeman, Montana, in June and July of 2011 and 2012.

Embryo results

Across all trials, embryo exposure to any level of UV-B resulted in complete mortality (Table 1; Tables S1, S2, S3, S4, S5, and S6, Supplemental Material). Mortality of control treatments (0% UV-B) varied markedly by female and ranged from 5.0% to 100.0% for individual females across all trials; mean embryo mortality was 64.6% in control treatments. Across all 2011 trials and treatments, mortality was highest (P < 0.001, F  =  35.576) on day 2 of UV-B exposure (76.5 ± 6.1%; Figure 2a). In contrast, mean mortality for day 1 and 3 of UV-B exposure was 11.5 ± 6.6% and 3.0 ± 1.3%, respectively. Although trials 1 and 2 were carried out for only 5 d, trials 3, 4, and 5 were run for 9, 11, and 10 d, respectively. Results from these latter trials indicate that no additional mortality occurred after 5 d in the control group. Trial 6, conducted in 2012, had the same exposure doses (UV-B treatments × exposure time) as the 2011 trials but included a Pyrex UV-C filter; UV-B related mortality patterns observed in these trials were nearly identical to trends in mortality documented in 2011 (Figure 2b).

Figure 2.

Woundfin Plagopterus argentissimus embryo mortality summarized by 14.5-h daily ultraviolet-B (UV-B) treatment over a 5-d exposure period. We exposed woundfin to UV-B radiation treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25% of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. The control is 0% UV-B. Panel (a) presents results from experimental exposures that did not include an ultraviolet-C (UV-C) shield. Panel (b) presents results from embryos that were covered by Pyrex dishes used to block UV-C across all UV-B treatments and the control. Embryo mortality is expressed as a percentage. We conducted trials in a controlled experimental UV-B exposure chamber at the Bozeman Fish Technology Center in Bozeman, Montana, during June and July of 2011 and 2012.

Figure 2.

Woundfin Plagopterus argentissimus embryo mortality summarized by 14.5-h daily ultraviolet-B (UV-B) treatment over a 5-d exposure period. We exposed woundfin to UV-B radiation treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25% of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. The control is 0% UV-B. Panel (a) presents results from experimental exposures that did not include an ultraviolet-C (UV-C) shield. Panel (b) presents results from embryos that were covered by Pyrex dishes used to block UV-C across all UV-B treatments and the control. Embryo mortality is expressed as a percentage. We conducted trials in a controlled experimental UV-B exposure chamber at the Bozeman Fish Technology Center in Bozeman, Montana, during June and July of 2011 and 2012.

Table 1.

Mean percentage of mortality of woundfin Plagopterus argentissimus embryos following 5 d of exposure to four levels of the ambient ultraviolet-B (UV-B) radiation for 14.5 h daily. We exposed woundfin to UV-B radiation treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We conducted trial 6 at the same dose and exposure time as the previous five trials; however a Pyrex dish was used to eliminate ultraviolet-C (UV-C). We conducted all trials at the Bozeman Fish Technology Center in Bozeman, Montana, from May to July of 2011 and June 2012.

Mean percentage of mortality of woundfin Plagopterus argentissimus embryos following 5 d of exposure to four levels of the ambient ultraviolet-B (UV-B) radiation for 14.5 h daily. We exposed woundfin to UV-B radiation treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We conducted trial 6 at the same dose and exposure time as the previous five trials; however a Pyrex dish was used to eliminate ultraviolet-C (UV-C). We conducted all trials at the Bozeman Fish Technology Center in Bozeman, Montana, from May to July of 2011 and June 2012.
Mean percentage of mortality of woundfin Plagopterus argentissimus embryos following 5 d of exposure to four levels of the ambient ultraviolet-B (UV-B) radiation for 14.5 h daily. We exposed woundfin to UV-B radiation treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We conducted trial 6 at the same dose and exposure time as the previous five trials; however a Pyrex dish was used to eliminate ultraviolet-C (UV-C). We conducted all trials at the Bozeman Fish Technology Center in Bozeman, Montana, from May to July of 2011 and June 2012.

Larval results

Exposure to any level of UV-B resulted in 100% mortality of larval woundfin (Table 2; Tables S7, S8, S9, S10, and S11, Supplemental Material). Across all trials, larval mortality differed by day (P  =  0.021, F  =  3.691), and mean mortality tended to be highest on days 2 and 3 (22.7 ± 9.9% and 21.0 ± 5.7%, respectively). Despite these patterns of mortality, larval mortality was documented on all 5 d of UV-B exposure (Figure 3; Figure S1, Supplemental Material). For the 50% UV-B treatments, no mortality was documented within the first 24 h of exposure and only 1.7% of total mortality was documented on day 2; peak mortality was seen on day 4. In contrast, mortality was greatest (P < 0.001, F  =  23.33) on days 2 (49.3 ± 12.0%) and 3 (49.3 ± 10.9%) of 100% UV-B treatments, and by day 5, we documented complete mortality of all individuals exposed to 100% UV-B treatments. In trials 4 and 5 which contained two 0% UV-B controls, none of the larvae experienced mortality in either method of obtaining 0% UV-B.

Figure 3.

Woundfin Plagopterus argentissimus larval mortality summarized by 14.5-h daily ultraviolet-B (UV-B) treatment over a 5-d exposure period. We exposed woundfin to UV-B radiation treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. The control is 0% UV-B. Larval mortality is expressed as a percentage. We conducted trials during June and July of 2011 at the Bozeman Fish Technology Center in Bozeman, Montana.

Figure 3.

Woundfin Plagopterus argentissimus larval mortality summarized by 14.5-h daily ultraviolet-B (UV-B) treatment over a 5-d exposure period. We exposed woundfin to UV-B radiation treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. The control is 0% UV-B. Larval mortality is expressed as a percentage. We conducted trials during June and July of 2011 at the Bozeman Fish Technology Center in Bozeman, Montana.

Table 2.

Mean larval woundfin Plagopterus argentissimus percentage of mortality following exposure to 14.5-h doses at two levels of ultraviolet-B (UV-B) and two different UV-B controls (full-spectrum light or acetate-blocked UV-B). We exposed woundfin to UV-B radiation treatments of 0.060 and 0.030 mW/cm2 to simulate 100 and 50%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. All trials also included a 0% UV-B control. We carried out all experiments over a 5-d exposure period. Larvae were 2 d old at the start of trials 1 and 2, 5–6 d old for trial 3, 27–30 d old for trial 4, and 41–44 d old for trial 5. We conducted all trials at the Bozeman Fish Technology Center in Bozeman, Montana, in June and July of 2011.

Mean larval woundfin Plagopterus argentissimus percentage of mortality following exposure to 14.5-h doses at two levels of ultraviolet-B (UV-B) and two different UV-B controls (full-spectrum light or acetate-blocked UV-B). We exposed woundfin to UV-B radiation treatments of 0.060 and 0.030 mW/cm2 to simulate 100 and 50%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. All trials also included a 0% UV-B control. We carried out all experiments over a 5-d exposure period. Larvae were 2 d old at the start of trials 1 and 2, 5–6 d old for trial 3, 27–30 d old for trial 4, and 41–44 d old for trial 5. We conducted all trials at the Bozeman Fish Technology Center in Bozeman, Montana, in June and July of 2011.
Mean larval woundfin Plagopterus argentissimus percentage of mortality following exposure to 14.5-h doses at two levels of ultraviolet-B (UV-B) and two different UV-B controls (full-spectrum light or acetate-blocked UV-B). We exposed woundfin to UV-B radiation treatments of 0.060 and 0.030 mW/cm2 to simulate 100 and 50%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. All trials also included a 0% UV-B control. We carried out all experiments over a 5-d exposure period. Larvae were 2 d old at the start of trials 1 and 2, 5–6 d old for trial 3, 27–30 d old for trial 4, and 41–44 d old for trial 5. We conducted all trials at the Bozeman Fish Technology Center in Bozeman, Montana, in June and July of 2011.

Susceptibility of larvae to UV-B appears to be a function of larval age during the first few days of exposure (Figure S2, Supplemental Material). Larvae used in these trials varied in age from 2 days in trials 1 and 2 to 41–44 days in trial 5. For the 100% UV-B treatments, larval age explained ≥ 78% of the variation in the mortality seen in day 2 and day 3. For example, on day 2 of the experiment, documented mortality averaged 66.7% for 2-d-old larvae to 6.7% for 43.5-d-old larvae in the 100% UV-B treatments (R  =  −0.887, P  =  0.045).

Ultraviolet-B mitigation strategies

All three UV-B mitigation strategies reduced incoming levels of UV-B. A single treatment of 90% black knitted shade cloth eliminated 92.9 ± 0.4% of the pretreatment levels UV-B levels at a depth of 60 cm. In addition, UV-B levels were inversely related with concentration of both Aquashade aquatic dye (P < 0.001; R2  =  0.967) and DOC (P  =  0.002; R2  =  0.480; Figure 4). At a depth of 60 cm, an Aquashade concentration of 9.0 mg/L attenuated approximately 95% of pretreatment UV-B. In contrast, DOC concentrations attenuated approximately 20 to 25% of UV-B at concentrations ≥ 4 mg/L (Figure 4).

Figure 4.

We explored mitigation techniques as methods to reduce incoming ultraviolet-B (UV-B) radiation that woundfin Plagopterus argentissimus were exposed to during captive rearing at conservation propagation facilities. The UV-B irradiance is expressed as a function of Aquashade® and dissolved organic carbon (DOC) concentrations, which were manipulated using sucrose (C12H22O11). We tested mitigation techniques at the Bozeman Fish Technology Center in Bozeman, Montana, in July 2011. We took all UV-B measurements in outdoor tanks at a depth of 60 cm.

Figure 4.

We explored mitigation techniques as methods to reduce incoming ultraviolet-B (UV-B) radiation that woundfin Plagopterus argentissimus were exposed to during captive rearing at conservation propagation facilities. The UV-B irradiance is expressed as a function of Aquashade® and dissolved organic carbon (DOC) concentrations, which were manipulated using sucrose (C12H22O11). We tested mitigation techniques at the Bozeman Fish Technology Center in Bozeman, Montana, in July 2011. We took all UV-B measurements in outdoor tanks at a depth of 60 cm.

Discussion

There is evidence that UV-B has detrimental effects on early life stages of fishes (Hunter et al. 1979; Kouwenberg et al. 1999; Häkkinen et al. 2002; Weigand et al. 2004; Dong et al. 2007). Specifically, UV-B increased mortality in northern anchovy Engraulis mordax (Hunter et al. 1979; Béland et al. 1999; Kouwenberg et al. 1999), Pacific mackerel Scomber japonicus (Hunter et al. 1979), bluegill sunfish Lepomis macrochirus (Gutiérrez-Rodríguez and Williamson 1999), and zebrafish Danio rerio (Dong et al. 2007) and elicited avoidance behavior in whitefish Coregonus albula and Coregonus lavaretus larvae (Ylönen et al. 2004). We show here that embryos and larvae of the endangered woundfin are sensitive to UV-B at a 14.5-h exposure time, and that all woundfin embryos and larvae exposed to UV-B during our trials experienced mortality. The UV-B–free treatments produced using full-spectrum lights or by shielding woundfin with acetate film resulted in significantly lower levels of mortality. Although woundfin in the 2011 trials were also exposed to UV-C, the trial in which we excluded UV-C with Pyrex dishes showed that the mortality patterns observed were nearly identical to 2011 results and confirmed that mortality was induced by UV-B rather than UV-C. Our work also demonstrates that larvae differ in their sensitivity to UV-B; susceptibility of larvae to UV-B appears to be a function of age at exposure. Here, we show that the youngest larvae (2 d posthatch) experienced an order of magnitude greater mortality than 43.5-d-old larvae after just 2 d of UV-B exposure. This finding is consistent with work with other fish species (Kouwenberg et al. 1999; Wiegand et al. 2004). For example, goldfish Carassius auratus embryo sensitivity to UV-B increased with increased cumulative exposure and embryos that were 25-h postfertilization were the most vulnerable to even a short (2- to 4-h) exposure to elevated UV-B. For zebrafish, the hatching success, incidence of malformations, and mortality varied significantly among embryonic stage classes. Interestingly, a greater incidence of malformations and higher mortality occurred when embryos were exposed more than 3 h postfertilization.

Recent evidence shows that zebrafish embryos raised in outdoor ponds were more tolerant to UV-B than laboratory-raised embryos (Dong et al. 2007). One explanation for the documented differences in zebrafish survival is individual variability in the expression of screening pigments. Screening pigments such as melanin can reduce the effects of UV-B radiation on fish and amphibians (Häkkinen et al. 2002; Garcia et al. 2009). However, Dong et al. (2007) found no measurable differences in zebrafish embryo pigmentation that would explain differences in mortality. Although larval woundfin begin developing visible dorsal melanophores within a few days of hatching (Snyder et al. 2011), both embryos and larvae were vulnerable to UV-B. Larval woundfin raised in outdoor ponds at the aforementioned facilities experience phytoplankton blooms (i.e., Southwestern Native Aquatic Resources and Recovery Center) and therefore may have less pigmentation than larval woundfin raised indoors, a phenomenon observed in razorback sucker Xyrauchen texanus (R. Muth, U.S. Fish and Wildlife Service, unpublished data). Alternatively, in outdoor ponds or streams that are clear (i.e., Bubbling Ponds) and have low DOC levels, woundfin larvae may have more pigmentation than conspecifics raised indoors. Because pigmentation may offer photoprotection, future work should attempt to quantify the pigmentation levels for woundfin used in experiments.

Our results show that the survivable level of UV-B radiation for developing woundfin embryos is < 0.015 mW/cm2 or < 25% of the ambient levels present at Bubbling Ponds at ≥ 14.5-h exposures. We realize that the environmentally relevant exposure period would be much lower than a 14.5-h exposure, and we have initiated preliminary research to examine the response of woundfin to exposure times and doses that more closely mimic natural, daily changes in UV-B. For example, recent work at the Bozeman Fish Technology Center demonstrates that exposing woundfin to the ambient levels of UV-B radiation found at Bubbling Ponds during the spawning season for ≤ 5 h seems to induce very low UV-B related mortality (M.A.H. Webb, N. Pinkham, and A.M. Ray, unpublished). As a result of these preliminary findings, we believe that the UV-B related mortality threshold for ambient levels of UV-B present at Bubbling Ponds is between 5 and 14.5 h of exposure. Further work is needed to document the actual survivable level of UV-B in order to decrease the negative effects of UV-B radiation on production. In addition, current levels of UV-B at other conservation propagation facilities should be documented to better understand UV-B factors limiting production elsewhere. Furthermore, quantifying levels of UV-B in the Virgin River system at spawning and rearing locations would be beneficial for understanding if UV-B radiation is limiting natural recruitment of woundfin.

Given our results, future work should examine whether reductions in UV-B radiation lead to decreases in woundfin mortality and increases in production in the captive rearing facilities described above. Ultraviolet-B radiation has also been shown to interact synergistically with other stressors (including pH and contaminants; Bancroft et al. 2008). Our data suggest that woundfin embryos and larvae are sensitive to UV-B and could therefore experience higher mortality rates at low UV-B doses if other stressors are present. Reduction in UV-B radiation could be accomplished in a number of ways, including the creation of UV-B–free refugia (i.e., areas of decreased UV-B; Ylönen et al. 2004) in individual rearing ponds

In summary, our work shows that woundfin embryos and larvae are vulnerable to UV-B levels > 0.015 mW/cm2 at temperatures ranging from 18.5 to 24.5°C and that the survivable threshold for exposure time is less than 14.5 h for this dose. This work will help raise awareness for propagation facilities about the effects of UV-B on early developmental stages of the federally listed woundfin but also provide insight on UV-B mitigation strategies that could be deployed to minimize exposure in outdoor rearing facilities.

Supplemental Material

Please note: The Journal of Fish and Wildlife Management is not responsible for the content or functionality of any supplemental material. Queries should be directed to the corresponding author for the article.

Reference S1. [USFWS] U.S. Fish and Wildlife Service. 1994. Virgin River fishes recovery plan. U.S. Fish and Wildlife Service, Salt Lake City, Utah.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S1 (2.6 MB PDF).

Figure S1. Woundfin Plagopterus argentissimus larval mortality summarized by 14.5-h daily ultraviolet-B (UV-B) treatment over a 5-d exposure period. We exposed woundfin to UV-B radiation treatments of 0.060, 0.030, and 0.015 mW/cm2 to simulate 100, 50, and 25% of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. The control is 0% UV-B. Larval mortality is expressed as a percentage. We conducted trials during June and July of 2011 at the Bozeman Fish Technology Center in Bozeman, Montana.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S2 (23 KB DOCX).

Figure S2. Woundfin Plagopterus argentissimus embryo mortality at different ages posthatch when exposed to 14.5 h daily ultraviolet-B (UV-B) treatments imitating 100% of the ambient UV-B (0.060 mW/cm2) radiation present at a depth of 60 cm in ponds at Bubbling Ponds State Fish Hatchery, Arizona. All trials were conducted for 5 d. Larvae were 2, 5–6, 27–30, and 41–44 d old when exposed to UV-B. We exposed all larvae to UV-B in an experimental exposure chamber at the Bozeman Fish Technology Center, Bozeman, Montana in June and July of 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S3 (56 KB PDF).

Table S1. Trial 1 summary of woundfin Plagopterus argentissimus embryo mortality. Mortality data are summarized by female and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We collected embryos for trial 1 from two females. Ultraviolet -B radiation treatments were 0.060, 0.030, and 0.015 mW/cm2, and we used these treatments to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We conducted trial 1 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on May 26, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S4 (13 KB DOCX).

Table S2. Trial 2 summary of woundfin Plagopterus argentissimus embryo mortality. Mortality data are summarized by female and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We collected embryos for trial 2 from two females. Ultraviolet -B radiation treatments were 0.060, 0.030, and 0.015 mW/cm2, and we used these treatments to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We conducted trial 2 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on June 7, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S5 (13 KB DOCX).

Table S3. Trial 3 summary of woundfin Plagopterus argentissimus embryo mortality. Mortality data are summarized by female and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We collected embryos for trial 3 from three females. Ultraviolet -B radiation treatments were 0.060, 0.030, and 0.015 mW/cm2, and we used these treatments to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We conducted trial 3 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on June 11, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S6 (13 KB DOCX).

Table S4. Trial 4 summary of woundfin Plagopterus argentissimus embryo mortality. Mortality data are summarized by female and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We collected embryos for trial 4 from three females. Ultraviolet -B radiation treatments were 0.060, 0.030, and 0.015 mW/cm2, and we used these treatments to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We conducted trial 4 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on June 15, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S7 (13 KB DOCX).

Table S5. Trial 5 summary of woundfin Plagopterus argentissimus embryo mortality. Mortality data are summarized by female and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We collected embryos for trial 5 from three females. Ultraviolet -B radiation treatments were 0.060, 0.030, and 0.015 mW/cm2, and we used these treatments to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We conducted trial 5 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on June 21, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S8 (13 KB DOCX).

Table S6. Trial 6 summary of woundfin Plagopterus argentissimus embryo mortality. Mortality data are summarized by female and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We collected embryos for trial 6 from two females. Ultraviolet -B radiation treatments were 0.060, 0.030, and 0.015 mW/cm2, and we used these treatments to simulate 100, 50, and 25%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. All treatments contained a Pyrex ultraviolet-C filter to determine if ultraviolet-C influenced the results of trials 1–5. We conducted trial 6 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on June 15, 2012.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S9 (13 KB DOCX).

Table S7. Trial 1 summary of woundfin Plagopterus argentissimus larval mortality. Mortality data are summarized by incubation cup and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We selected larvae from a tank containing mixed progeny from multiple females. Ultraviolet -B radiation treatments were 0.060 and 0.030 mW/cm2, and these treatments were used to simulate 100 and 50%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. Larvae were 2 d old at the start of trial 1. Each exposure chamber for trial 1 contained only one incubation cup with five larvae because of the limited number of larvae available for this trial. We conducted trial 1 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on June 3, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S10 (12 KB DOCX).

Table S8. Trial 2 summary of woundfin Plagopterus argentissimus larval mortality. Mortality data are summarized by incubation cup and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We selected larvae from a tank containing mixed progeny from multiple females. Ultraviolet-B radiation treatments were 0.060 and 0.030 mW/cm2, and these treatments were used to simulate 100 and 50%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. Larvae were 2 d old at the start of trial 2. We conducted trial 2 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on June 30, 2011S:\3B2\ERS\erj\non-issue 3d\2014-5-14.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S11 (12 KB DOCX).

Table S9. Trial 3 summary of woundfin Plagopterus argentissimus larval mortality. Mortality data are summarized by incubation cup and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed UV-B treatments using a 14.5-h exposure period each day. We selected larvae from a tank containing mixed progeny from multiple females. Ultraviolet-B radiation treatments were 0.060 and 0.030 mW/cm2, and these treatments were used to simulate 100 and 50%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. Larvae were 5–6 d old at the start of trial 3. We conducted trial 3 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on July 5, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S12 (12 KB DOCX).

Table S10. Trial 4 summary of woundfin Plagopterus argentissimus larval mortality. Mortality data are summarized by incubation cup and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed treatments using a 14.5-h exposure time at two levels of UV-B and two different UV-B controls (full-spectrum light [FSL] or acetate-blocked UV-B [acetate]). Ultraviolet-B radiation treatments were 0.060 and 0.030 mW/cm2, and these treatments were used to simulate 100 and 50%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We selected larvae from a tank containing mixed progeny from multiple females. Larvae were 27–30 d old at the start of trial 4. We conducted trial 4 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on July 11, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S13 (12 KB DOCX).

Table S11. Trial 5 summary of woundfin Plagopterus argentissimus larval mortality. Mortality data are summarized by incubation cup and ultraviolet-B (UV-B) exposure treatment over a 5-d observation period. We imposed treatments using a 14.5-h exposure time at two levels of UV-B and two different UV-B controls (full spectrum light [FSL] or acetate-blocked UV-B [acetate]). Ultraviolet-B radiation treatments were 0.060 and 0.030 mW/cm2, and these treatments were used to simulate 100 and 50%, respectively, of the ambient irradiance levels documented in outdoor ponds at Bubbling Ponds State Fish Hatchery. We included a 0% UV-B treatment as a control. We selected larvae from a tank containing mixed progeny from multiple females. Larvae were 41–44 d old at the start of trial 5. We conducted trial 5 at the Bozeman Fish Technology Center in Bozeman, Montana, beginning on July 25, 2011.

Found at DOI: http://dx.doi.org/10.3996/042013-JFWM-030.S14 (12 KB DOCX).

Acknowledgments

The authors wish to thank Cal Fraser (Bozeman Fish Technology Center), Manuel Ulibarri (Southwestern Native Aquatic Resources and Recovery Center), Zane Olsen (Wahweap State Fish Hatchery), Matt O'Neill (Bubbling Ponds State Fish Hatchery), and Steve Meismer (Virgin River Resource Management and Recovery Program) for their woundfin expertise and support of this project and Taylor Wilcox, Sierra Alexander, and Brittany Buchholz for assistance with spawning woundfin. The authors would also like to thank the Subject Editor and three anonymous reviewers for comments that greatly improved the flow and clarity of this manuscript.

The Blaustein Laboratory at Oregon State University provided acetate for the trials.

This study was funded by the Virgin River Resource Management and Recovery Program.

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

References

References
Bancroft
BA
,
Baker
NJ
,
Blaustein
AR
.
2007
.
Effects of UV-B radiation on marine and freshwater organisms: a synthesis through meta-analysis
.
Ecology Letters
10
:
332
345
.
Bancroft
BA
,
Baker
NJ
,
Blaustein
AR
.
2008
.
A meta-analysis of the effects of ultraviolet B radiation and its synergistic interactions with pH, contaminants, and disease on amphibian survival
.
Conservation Biology
22
:
987
996
.
Béland
F
,
Browman
HI
,
Rodriguez
CA
,
St-Pierre
JF
.
1999
.
Effect of solar ultraviolet radiation (280–400 nm) on the eggs and larvae of Atlantic cod (Gadus morhua)
.
Canadian Journal of Fisheries and Aquatic Sciences
56
:
1058
1067
.
Bukaveckas
PA
,
Robbins-Forbes
M
.
2000
.
Role of dissolved organic carbon in the attenuation of photosynthetically active and ultraviolet radiation in Adirondack lakes
.
Freshwater Biology
43
:
339
354
.
Buma
AGJ
,
Boelen
P
,
Jeffrey
WH
.
2003
.
UVR-induced DNA damage in aquatic organisms
. Pages
291
327
in:
Helbling
ER
,
Zagarese
H
,
editors
.
UV effects in aquatic organisms and ecosystems
.
Cambridge, UK
.
Royal Society of Chemistry
.
Calfee
RD
,
Little
EE
,
Pearl
CA
,
Hoffman
RL
.
2010
.
Effects of simulated solar UVB radiation on early developmental stages of the northwestern salamander (Ambystoma gracile) from three lakes
.
Journal of Herpetology
44
:
572
580
.
Cracknell
AP
,
Varatsos
CA
.
2009
.
The contribution of remote sensing to the implementation of the Montreal Protocol and the monitoring of its success
.
International Journal of Remote Sensing
30
:
3853
3873
.
Dong
Q
,
Svoboda
K
,
Tiersh
TR
,
Monroe
WT
.
2007
.
Photobiological effects of UVA and UVB light in zebrafish embryos: evidence for a competent photorepair system
.
Journal of Photochemistry and Photobiology
88
:
137
146
.
Douki
T
.
2010
.
Thymine cyclobutane dimers: the most frequent and persistent DNA lesions in skin exposed to both UVB and UVA
.
Expert Review of Dermatology
5649
657
.
[ESA] U.S. Endangered Species Act of 1973, as amended, Pub. L. No. 93-205, 87 Stat. 884 (Dec. 28, 1973)
. .
French
D
,
Lindley
D
.
2000
.
Exploring the data
. Pages
33
69
in:
Sparks
T
,
editor
.
Statistics in ecotoxicology
.
Chichester, UK
.
John Wiley & Sons
.
Garcia
TS
,
Paoletti
DJ
,
Blaustein
AR
.
2009
.
Correlated trait response: comparing amphibian defense strategies across a stress gradient
.
Canadian Journal of Zoology
87
:
41
49
.
Gutiérrez-Rodriguez
C
,
Williamson
CE
.
1999
.
Influence of solar ultraviolet radiation on early life-history stages of the bluegill sunfish, Lepomis macrochirus
.
Environmental Biology of Fishes
55
:
307
319
.
Häder
DP
,
Worrest
RC
,
Kumar
HD
.
1995
.
Effects of solar ultraviolet radiation on aquatic ecosystems
.
Ambio
24
:
174
180
.
Häkkinen
J
,
Vehniäinen
E
,
Ylönen
O
,
Heikkilä
J
,
Soimasuo
M
,
Kaurola
J
,
Oikari
A
,
Karjalainen
J
.
2002
.
The effects of increasing UV-B radiation on pigmentation, growth and survival of coregonid embryos and larvae
.
Environmental Biology of Fishes
64
:
451
459
.
Hunter
RJ
,
Taylor
JH
,
Moser
HG
.
1979
.
Effect of ultraviolet irradiation on eggs and larvae of the northern anchovy, Engraulis mordax, and the Pacific mackerel, Scomber japonicus, during the embryonic stage
.
Photochemistry and Photobiology
29
:
325
338
.
Kouwenberg
JHM
,
Browman
HI
,
Cullen
JJ
,
Davis
RF
,
St.-Pierre
JF
,
Runge
JA
.
1999
.
Biological weighting of ultraviolet (280–400 nm) induced mortality in marine zooplankton and fish. I. Atlantic cod (Gadus morhua) eggs
.
Marine Biology
134
:
269
284
.
Lepre
AM
,
Sutherland
JC
,
Trunk
JG
,
Sutherland
BM
.
1998
.
A robust, inexpensive filter for blocking UV-C radiation in broad-spectrum ‘UV-B’ lamps
.
Journal of Photochemistry and Photobiology B: Biology
43
:
34
40
.
Morris
DP
,
Zagarese
H
,
Williamson
CE
,
Balseiro
EG
,
Hargreaves
BR
,
Modenutti
B
,
Moeller
R
,
Queimalinos
C
.
1995
.
The attenuation of solar UV radiation in lakes and the role of dissolved organic carbon
.
Limnology and Oceanography
40
:
1381
1391
.
Romansic
JM
,
Waggener
AA
,
Bancroft
BB
,
Blaustein
AR
.
2009
.
Influence of ultraviolet-B radiation on growth, prevalence of deformities, and susceptibility to predation in Cascades frog (Rana cascadae) larvae
.
Hydrobiologia
624
:
219
233
.
Snyder
DE
,
Charles
JA
,
Bjork
CL
.
2011
.
Illustration and description of woundfin larvae and early juveniles—contribution to a guide to larval fishes of the Virgin River
.
Report of Larval Fish Laboratory, Department of Fish, Wildlife, & Conservation Biology, Colorado State University to Virgin River Resource Management and Recovery Program, Salt Lake City, Utah
.
[USFWS] U.S. Fish and Wildlife Service
.
1970
.
Conservation of endangered species and other fish and wildlife
.
Federal Register
35
:
16047
16048
.
[USFWS] U.S. Fish and Wildlife Service
.
1994
.
Virgin River fishes recovery plan
.
US Fish and Wildlife Service, Salt Lake City, Utah (see Supplemental Material, Reference S1, http://dx.doi.org/10.3996/042013-JFWM-030.S1)
.
Webb
MAH
,
Pinkham
N
,
Ray
AM
.
U.S. Fish and Wildlife Service, National Park Service, Unpublished data
.
Wiegand
MD
,
Young
DLW
,
Gajda
BM
,
Thuen
DJM
,
Rittberg
DAH
,
Huebner
JD
,
Loadman
NL
.
2004
.
Ultraviolet light-induced impairment of goldfish embryo development and evidence for photorepair mechanisms
.
Journal of Fish Biology
64
:
1242
1256
.
Williamson
CE
,
Stemberger
RS
,
Morris
DP
,
Frost
TM
,
Paulsen
SG
.
1996
.
Ultraviolet radiation in North American lakes: attenuation estimates from DOC measurements and implications for plankton communities
.
Limnology and Oceanography
41
:
1024
1034
.
Ylönen
O
,
Huuskonen
H
,
Karjalainen
J
.
2004
.
UV avoidance of coregonid larvae
.
Annales Zoologici Fennici
41
:
89
98
.

Author notes

Holmquist LM, Ray AM, Bancroft BA, Pinkham N, Webb MAH. 2014. Effects of ultraviolet-B radiation on woundfin embryos and larvae with application to conservation propagation. Journal of Fish and Wildlife Management 5(1):87-98; e1944-687X. doi: 10.3996/042013-JFWM-030

The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service.