1. Eggs 2. Alevin 3. Fry 4. Fingerling 5. Adult First I would like to briefly tell you a little about the brook trout life-cycle. Brook trout reproduction begins when a female is ready to spawn in the fall and she builds a nest in the gravel of a stream called a ‘redd’ and then the male fertilizes the eggs by releasing sperm (called ‘milt’) over the eggs. After about one month, the eggs hatch and the alevins remain on the gravel bed and live off of the yolk-sac. When the yolk-sac is depleted, the alevins begin to swim in to the water column to seek food. After this swim-up phase, they are called fry. As they continue to grow, they are referred to as fingerlings and have vertical stripes which they eventually lose as they develop into adults.
The Effect of Water Quality on the Mortality and Fitness of Brook Trout (Salvelinus fontinalis) Eggs, Alevins and Fry in Aquaculture and Deep Springs along.
T. D. Teears1, 2, S. J. Baedke2, T. R. Benzing2, D. M. Downey2, N. F. Wilke1, C. L. May2. 1Virginia Department of Game and Inland Fisheries, VA. 2James Madison University, Harrisonburg, VA. Hi. I’m Thom Teears and I am very excited to share a few things I’ve learned about the effect of water quality on brook trout at early-life stages of development.
However, many brook trout populations in Virginia have been extirpated by anthropogenic impacts such as urbanization, sedimentation and industrialization. Even a natural-looking stream such as this may be affected by acidification, which is caused by the deposition of acidic compounds from the atmosphere or from contaminated runoff and groundwater.
Urbanization. Sedimentation from. agricultural land use. Industrialization.
Fisheries decline (Mason, 1990; Sayer et. al., 1993) Deposition of acidic compounds (Drever, 1997) Combustion. Smelting. Mining (Sulfides)
Alkalinity=ANC: Acid Neutralizing Capacity (Drever, 1997) Geology governs water quality. Limestone, calcite (CaCO3) Dolostone, dolomite (CaMg(CO3)2) High ANC provides higher resistance to acidification.
al., 1988) Many studies focus on early life stages development.
Bioassays (MacAvoy and Bulger, 1995) Higher ANC= increased survival.
Eastern Brook Trout Joint Venture (Hudy et. al., 2008; EBJTV, 2006) Evaluation. Stream ANC. Population assessment. Limestone sand. Water quality. Invertebrates. Ecosystem, biodiversity. Brook Trout.
Affects heart, muscle, nerves, bone, scales, metabolic functions etc.. Ca2+ from gills (primary) and diet (secondary) (Hwang et. al., 1996; Hwang and Hirano, 1985) Mg2+ from diet (primary) and gills (secondary) (Bijvelds et. al., 1996)
Metal Toxicity (Ingersoll et. al., 1990)
Spawning of brook trout in the main-stem of the South River (Waynesboro, VA) has been unsuccessful due to excess fine sediment from surrounding land-use practices. How effective would the deep springs along the South River in Waynesboro, VA be in supporting the establishment of a brook trout fisheries Thermal refuge. Springs have no excess fine sedimentation. Unique chemistry due to geology. The South River in Waynesboro is a popular fishing destination and there are many events that happen in Waynesboro like the Riverfest and the Fly Fishing Expo that attract many anglers to the area. However, brook trout have been unable to establish a sustainable population because they are unable to spawn in the main-stem of the South River due to excess fine sedimentation from surrounding land-use practices. The South River has many deep springs that contribute large volumes of cool water in to the main-stem of the South River. The question I set out to answer is how effective the South River springs would be for supporting the establishment of a brook trout fisheries The springs in the South River might offer a thermal refuge for a brook trout population if the water was suitable for hatching.
To begin to understand the impacts that water quality has on the mortality of brook trout eggs, I perfumed a pilot study where I setup 6 tanks with varying levels of calcium and magnesium water hardness as well as varying levels of acid neutralizing capacity which is often referred to as ANC. Water hardness is vital to osmotic regulation for maintaining proper blood chemistry. ANC is vital for buffering against changes in pH that can be detrimental to fish health. Mortality, growth rate and yolk-sac to whole-body area ratio were the variables of interest.
Each tank received 100 eyed eggs from the Marion Fish Hatchery where they maintain a brood stock for spawning to supply brook trout for production.
Alevins One week after hatch, 7 alevins were removed from each tank to determine yolk-sac to whole-body ratio.
Yolk-sac to whole body area ratio was determined using Image J software.
Fry When they began feeding, they were weighed weekly for individual growth rate.
Egg Size (Kruskal-Wallis rank sum test, p = 0.026, Nemenyi-test post-hoc )
On the x-axis is time and the y-axis is cumulative mortality. The 2 controls were Montebello Fish Culture Station spring water which has extremely low water hardness and ANC and the Marion Fish Hatchery spring water which has high levels of calcium water hardness and ANC and is also the hatchery of origin. The other four treatments were designed to mimic chemistry found in natural streams in the Shenandoah Valley. The most interesting results of this study was that the two tanks that had much lower mortality were Marion Fish Hatchery and 50 ppm CaCO3. Both of these tanks were high in calcium water hardness and ANC, which emphasize the importance of these two parameters in conjunction with each other. Marion had the lowest mortality which implies that there was a home field advantage because this is the water chemistry these brook trout have been raised in for many generations which creates a strong selective pressure driving this population to adapt to the chemistry of the hatchery. This advantage may be a genetic component from maternal effects. Another thing to notice is that when sulfate is coupled with magnesium as opposed to calcium, the mortality was much lower. All treatments statistically higher than Marion FH (Kolmogorov-Smirnov test, p<0.01).
On the x-axis is time and on the y-axis is total biomass per individual. The Marion FH and 50 ppm CaCo3 treatments had high growth rates, which concurs with the mortality results however the 12 ppm MgSO4 treatment also had high growth rates. This could be due to the lower density in that treatment as salmonids have been shown to have density-dependent growth rates. It also demonstrates that when sulfate is coupled with magnesium as opposed to calcium, the growth rates are higher. Another interesting result is the divergence of patterns of the three higher growth rate treatments from the three lower growth rate treatments. Is this a continuing trajectory even if all the treatments were put into the same water If there are long-term effects from early life-stage water quality, than this could emphasize the importance of giving brook trout a head start in an aquaculture setting during early life to increase fitness when stocked in a natural stream. (Mood’s median test, p = 0.156)
Here you can see for each treatment the boxplot for yolk-sac to whole-body area ratio. Both 12 ppm MgCO3 and 12 ppm MgSO4 were statistically lower than the four remaining treatments. Calcium is primarily acquired from the surrounding water via the gills where as magnesium is acquired primarily from diet so the lack of calcium for the development of bones, nerves and muscles may cause a more rapid depletion of the yolk-sac. Contrary to the previous results, when sulfate is coupled with magnesium as compared to calcium, the yolk-sac is depleted more quickly. However, this may be simply due to the uptake methods of calcium and magnesium. (Anova, p < 0.001, Tukey’s HSD post-hoc, A & B used to show subsets of significant differences)
Dolostone and Limestone geology in South River. Consistently cool water. Hatch brook trout eggs in-situ. Measure water quality at each site. Due to the dolomite and limestone geology in the South River area, the South River springs are high in calcium water hardness and ANC and also. Combined with the consistently cool water this could be an optimal place for brook trout to spawning. To test this, I tried a similar experiment in the South River springs. Water quality tested at each site. Samples analyzed in Dr. Dan Downey’s lab here at the JMU chemistry dept.
Afton mountain is to the east. This area is the south entrance to the Shenandoah National Park.
At each of the three springs along the South River, two heath trays were placed inside plastic mesh boxes secured with heavy duty plastic netting to allow water to flow in and out and prevent tampering. Perforated PVC slats were glued into the heath trays to form 9 separate compartments in each tray. Each compartment received 30 eyed-eggs from the Paint Bank Fish Hatchery. Each spring had 540 eggs in total to start with. Eggs were checked every three days and mortalities were counted and removed. This setup worked well for keeping eggs separated to prevent fungus from getting out of control but after hatch, alevins were able to move between the compartments so each heath tray was treated as a replicate instead of each compartment.
The Montebello hatchery was used as a control. Eggs were hatched in ponds 1 through 6. Each pond has a drop of several feet which aids in gas exchange. Main-stem water in a chilled aquarium tank was also used for hatching eggs as another control.
Each pond had 6 tubes. Pond 6 had two heath trays identical to the South River springs setup as well as 6 PVC tubes. Each compartment received 30 eyed-eggs from the Paint Bank Fish Hatchery. Eggs were checked every three days and mortalities were counted and removed. The PVC tubes were superior to the heath trays because fish were unable to move from one compartment to the other so each compartment was treated as a replicate.
In analyzing my results I found that dissolved nitrogen gas had a significant impact on mortality. On the x-axis is % nitrogen gas saturation. On the y-axis is percent mortality. We have the 3 springs sites, the main-stem water control and the Montebello Fish Cultural Station controls ponds 1 through 6. The 3 South River springs sites had fairly high nitrogen saturation and high mortality. Although there is a gap in the data set, the relationship between nitrogen gas saturation and percent mortality is demonstrated by this fairly strong R2 value. (Simple linear regression, p < 0.001)
Seasonal Nitrogen Fluctuations
Running the data with a step-wise regression the best-fit model removed calcium, which would be highly correlated with ANC but included UV, ANC and sulfate. As would be expected, UV increased mortality though only very slightly. As we saw in the lab study, sulfate correlates to a decrease in mortality. The surprising result is an increase in mortality caused by ANC. This could be simply a matter of the overarching effect of nitrogen in the South River springs where ANC was rather high as compared to Montebello, which has low nitrogen and ANC.
Revisit Nitrogen and mortality graph. (Simple linear regression, p < 0.001)
Gap in dataset. (Simple linear regression, p < 0.001)
Zero in on MFCS only. (Simple linear regression, p < 0.001)
Linear regression and exponential regression gave an R2 of <0.3. Using the data from only Montebello FCS showed the best-fit with a quadratic regression. This quadratic regression is a little surprising as it would be unexpected to see mortality increase at the low end of the range for nitrogen saturation. There may be other factors affecting mortality at the low end of the range that were unaccounted for. (Quadratic regression, p < 0.001)
%𝑀𝑜𝑟𝑡𝑎𝑙𝑖𝑡𝑦=3.79 𝑁 𝑈𝑉 −386.1.
6 Months at MFCS Ponds 1-6
In order to determine whether I could see evidence of the effects of nitrogen gas saturation I continued to rear the brook trout at MFCS for a total of 6 months and then sampled some of them to look for signs of gas bubble trauma. Here you can see the gas bubbles in the capillaries of the fin of this brook trout from pond one, which had the highest nitrogen gas saturation.
In order for South River springs to be optimal for hatching of brook trout, the water would need to have dissolved nitrogen gas removed. Springs along the South River have ideal calcium water hardness and ANC. The South River has optimal geology for brook trout. The springs also offer a thermal refuge. However, nitrogen gas saturation in the springs has an overarching negative impact on brook trout egg mortality. There is a potential for the springs to be used in an aquaculture setting if the dissolved nitrogen gas is reduced to acceptable levels. This research helps demonstrate that aquaculture is a powerful tool for answering research questions relating to fisheries management.
Sulfate: Friend of Foe Improves fitness with Magnesium compare to Calcium. ‘Home-Field’ Advantage: Adaption or Plasticity Application: Prescriptive Evolution. Growth Trajectory Application: ‘Head-Start’ in Aquaculture. Sulfate seems to have an improvement of fitness when with magnesium compared to calcium. One question raised by the ‘Home-Field’ advantage seen in the lab-study is whether it is adaptation or plasticity. This could an opportunity for further research. One application of this advantage would be to genetically fit brook trout in an aquaculture setting to the desired stream by rearing them in water similar to the geochemistry of the destination stream. If the growth trajectory remains from early-stage development, ‘head-start’ in aquaculture with high water quality.
In closing, I would like to thank the many people who have helped me with this research and Dr. Christine May and the fall Freshwater Ecology lab for their tireless efforts in making this research possible. Thank you. Special Thanks to Dr. Christine May’s Freshwater Ecology Lab.
107-day Pilot Study Chemistry
South River Chemistry Data
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PDF) The Effect of Water Quality on the Survival and Fitness of Brook Trout (Salvelinus fontinalis) Eggs, Alevins and Fry in Aquaculture and Deep Springs along the South River in Waynesboro, VA
Differences in embryo survivorship among populations of brook trout (Salvelinus fontinalis) under variable winter thermal regimes
PDF) The Effect of Water Quality on the Survival and Fitness of Brook Trout (Salvelinus fontinalis) Eggs, Alevins and Fry in Aquaculture and Deep Springs along the South River in Waynesboro, VA
The effect of water quality on the survival and fitness of brook trout (Salvelinus fontinalis) eggs, alevins and fry in aquaculture and deep springs along the South River in Waynesboro, VA
The Effect of Water Quality on the Mortality and Fitness of Brook
The effect of water quality on the survival and fitness of brook trout (Salvelinus fontinalis) eggs, alevins and fry in aquaculture and deep springs along the South River in Waynesboro, VA
Fishes, Free Full-Text