POTENTIAL ENVIRONMENTAL CHALLENGES OF HYPER-INTENSIVE BIOFLOC GROWOUT SYSTEMS

Transcription

1 POTENTIAL ENVIRONMENTAL CHALLENGES OF HYPER-INTENSIVE BIOFLOC GROWOUT SYSTEMS John W. Leffler and Jeff F. Brunson South Carolina Department of Natural Resources Marine Resources Research Institute Waddell Mariculture Center

2 Superintensive, Indoor, Minimal-exchange, Biofloc Shrimp Systems Advantages: Biosecurity High productivity Efficient & economical nitrogen control Supplemental food/nutrient recycling 235 m 3

3 Zero-Exchange Systems Water use Pollution Disease Problem: WASTE Accumulation Inorganics Organics Pathogens

4 Complete Reuse of Growout Water

5 Advantages of Water Reuse Reduce effluent. Retain established biofloc community for nitrification. Reduce expense of replacing sea salts at inland farms. Rapid turnover from harvest to stocking. Can substances accumulate in reused water that might inhibit shrimp production?

6 Feed µg/g Element 126 Al 0.90 As 14.0 B 0.32 Cd 13,128 Ca 2.17 Cr 12.7 Cu 421 Fe 0.00 Pb 9,321 Mg 42.2 Mn 1.33 Mo 56,450 N 1.43 Ni 8,699 P 12,585 K 2.48 Se 1,755 Na 4,927 S 110 Zn

7 Feed µg/g Chemical Accumulation in Water - Trial 17 Element Week 0 mg/l Week 18 mg/l Percent Change % 126 Al % 0.90 As % 14.0 B % 0.32 Cd % 13,128 Ca % 2.17 Cr % 12.7 Cu % 421 Fe % 0.00 Pb % 9,321 Mg % 42.2 Mn % 1.33 Mo % 56,450 N % 1.43 Ni % 8,699 P % 12,585 K % 2.48 Se % 1,755 Na % 4,927 S % 110 Zn % - Typical 18 week growout shrimp/m day growout

8 Feed µg/g Chemical Accumulation in Water - Trial 17 Element Week 0 mg/l Week 18 mg/l Percent Change % 126 Al % 0.90 As % 14.0 B % 0.32 Cd % 13,128 Ca % 2.17 Cr % 12.7 Cu % 421 Fe % 0.00 Pb % 9,321 Mg % 42.2 Mn % 1.33 Mo % 56,450 N % 1.43 Ni % 8,699 P % 12,585 K % 2.48 Se % 1,755 Na % 4,927 S % 110 Zn % - Typical 18 week growout shrimp/m day growout

9 Chemical Accumulation in Shrimp (whole body) during a Growout Trial Stocked at 414 m d growout Chemical Accumulation in Shrimp - Trial 17 Element Week 0 (µg/g) Week 18 (µg/g) Percent Change (%) Al As B Cd Ca 34,449 24, Cr Cu Fe Pb ,471 Mg 3,033 2, Mn Mo ,900 N 61,000 76, Ni P 12,085 11, K 13,077 14, Se ,757 Na 8,193 7, S 7,627 7, Zn

10 Chemical Composition of Shrimp Harvested from ProductionTrial 17 versus Shrimp from other Sources Trial 17 vannamei Thailand pond vannamei* SC pond vannamei* SC wild setiferus* Element µg/g wet weight µg/g wet weight µg/g wet weight µg/g wet weight Aluminum U.S. EPA Screening Values U.S. FDA Action Levels Arsenic ** 76 Cadmium Chromium Copper Iron Lead Manganese Nickel Selenium Zinc * Leffler, Unpublished data. Assumes a wet weight to dry weight conversion of **SV based on inorganic As only; SV adjusted for ~4% inorganic As in wet weight.

11 Relative Changes in Elements in Water During Prototype Commercial Raceway Trials Trial 15 Trial 16 Trial 17 Trial 19 Trial 20 Al As B Cd Ca ++ - Cr Cu Fe Pb - - Mg ++ + Mn Mo N x x Ni P K Se Na x x S - Zn *Shrimpdays/m 192,708 88,164 52,992 64,512 62,248 * Shrimp days = stocking rate x days of water use Measured changes in element concentrations in five trials of the prototype commercial raceway. + = 10% - 99% change ++ = 100% - 999% change +++ = > 1000% change

12 Relative Changes in Elements in Water During Prototype Commercial Raceway Trials Trial 15 Trial 16 Trial 17 Trial 19 Trial 20 Al As B Cd Ca ++ - Cr Cu Fe Pb - - Mg ++ + Mn Mo N x x Ni P K Se Na x x S - Zn *Shrimpdays/m 192,708 88,164 52,992 64,512 62,248 * Shrimp days = stocking rate x days of water use Macro-nutrients N and P increase significantly in higher concentrations. + = 10% - 99% change ++ = 100% - 999% change +++ = > 1000% change

13 Relative Changes in Elements in Water During Prototype Commercial Raceway Trials Trial 15 Trial 16 Trial 17 Trial 19 Trial 20 Al As B Cd Ca ++ - Cr Cu Fe Pb - - Mg ++ + Mn Mo N x x Ni P K Se Na x x S - Zn *Shrimpdays/m 192,708 88,164 52,992 64,512 62,248 * Shrimp days = stocking rate x days of water use Micro-nutrients Cu, Fe, Mn, and Zn increase significantly in lower concentrations. + = 10% - 99% change ++ = 100% - 999% change +++ = > 1000% change

14 Relative Changes in Elements in Water During Prototype Commercial Raceway Trials Trial 15 Trial 16 Trial 17 Trial 19 Trial 20 Al As B Cd Ca ++ - Cr Cu Fe Pb - - Mg ++ + Mn Mo N x x Ni P K Se Na x x S - Zn *Shrimpdays/m 192,708 88,164 52,992 64,512 62,248 * Shrimp days = stocking rate x days of water use Could reused water alter the biofloc community? Could reused water limit shrimp production? + = 10% - 99% change ++ = 100% - 999% change +++ = > 1000% change

15 Growth rate (g/week) Experiment 1: First Experiment Reused water (>212 >900 shrimp/m 3 ) Serial dilutions in 60 L aquaria 10 shrimp/tank; grown for 23 days Concluded: Increased reused water led to decreased growth Growth Rate of Shrimp in Serially Diluted Reused Raceway Water R² = % 10% 25% 50% 75% 100% Serial Dilutions of Reused Raceway Water

16 Experiment 2: Second Experiment 206 day-old water from a production raceway Diluted with fresh filtered seawater 18 concentrations from 100% to 0% reused biofloc water Concentrations of reused water 60 L aquaria/circulating water bath 10 shrimp (~1.98 g) per tank 36 days

17 g/shrimp g/tank Experiment 2: Mean Weight Gain per Shrimp over 36 Days adjusted R² = P = % 20% 40% 60% 80% 100% Percent of 206 day-old "reused" water Results Increasing amounts of Reused Water: No effect on Survival (adj. R 2 = 0.000, P = 0.922) Decreased Growth Rate (adj. R 2 = 0.414, P = 0.002) Decreased Overall Production (adj. R 2 = 0.214, P = 0.031) Production per Tank over 36 Days adjusted R² = P = % 20% 40% 60% 80% 100% Percent of 206 day-old "reused" water Conclusion: Reused biofloc water depresses shrimp growth!

18 Experiment 3: Is the depressed growth associated with reused water due to high accumulated NO 3 -N levels? Concentrations of reused water mg L Mean NO 3 -N & Alkalinity across Dilutions % Reused Water NO3-N Alkalinity Concentrations of nitrate NaNO 3 in fresh filtered seawater 19 NO 3 -N concentrations: 13 to 1157 mg-l shrimp (mean weight = 4.23 ± 0.23 g) per tank 32 days

19 grams grams Experiment 3: Results No effect on Survival. Significant negative relationship between [NO 3 -N] and Growth Rate and Total Production. 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Survival by [NO 3 -N] Level NO 3 -N Concentration Mean Individual Weight Gain by [NO 3 -N] Level adjusted R² = P < NO 3 -N Concentration Tank Production by [NO 3 -N] Level adjusted R² = P < NO 3 -N Concentration

20 Biological Problems Related to Biofloc

21 Shrimp Feed Shrimp Waste Bacteria Cyanobacteria Green Algae Diatoms Dinoflagellates BIOFLOC Chemoautotrophs Photoautotrophs Heterotrophs Benefits Water Quality Supplemental Nutrition Solids NO 3 Wastes

22 The Good, the Bad, and the Ugly BioFloc Photo by M. Parrow, Center for Applied Aquatic Ecology.

23 5/9 5/16 5/23 5/30 6/6 6/13 6/20 6/27 7/4 7/11 7/18 7/25 8/1 8/8 8/15 8/22 8/29 9/5 9/12 9/19 9/26 10/3 10/10 BioFloc Composition Changes over Time restocked harvest Bacteria Cyanobacteria Green algae Diatoms Dinoflagellates Pfiesteria, PLOs Heterotrophic protistans Heterotrophic animals

24 Dissolved Oxygen (mg/l) ph Algal Crashes Can Trigger Major Mortality Events Chlorophyll (µg/l) /26 6/2 6/9 6/16 6/23 6/30 7/7 Estimated Shrimp Biomass/m /26 6/2 6/9 6/16 6/23 6/30 7/7 Stocked at 336/m 3 Growth = 1.85 g/wk; FCR = 1.04 Algal crash: 96.5% shrimp mortality. No sudden drop in DO or ph Microbial community disappeared except for 2 nontoxic cryptomonads and a few filamentous bacteria. DO and ph during Trial /24 5/31 6/7 6/14 6/21 6/28 7/ DO ph

25 Dissolved Oxygen (mg/l) ph μg/l Algal Crashes Can Trigger Major Mortality Events Chlorophyll (µg/l) Total Chlorophyll /26 6/2 6/9 6/16 6/23 6/30 7/ Estimated Shrimp Biomass/m 3 8-Jun 23-Jun 8-Jul 21-Jul 5-Aug Estimated Biomass in Photoautotrophic Raceway /26 6/2 6/9 6/16 6/23 6/30 7/7 kg/m DO and ph during Trial /24 5/31 6/7 6/14 6/21 6/28 7/ Jun 22-Jun 6-Jul 20-Jul 3-Aug Another raceway Another algal crash Another shrimp crash DO ph

26 Biofloc Changes May Influence Shrimp Growth 1.60 Diatoms in a bacterial matrix RW1Mean Wt RW2 Mean Wt 4/18 4/25 5/2 5/9 5/16 5/23 5/30 6/6 6/13 Growth rates of PL s stocked in identical raceways diverged. Growth rates converged as biofloc community structures converged. Synechococcus dominated (cyanobacteria)

27 grams Impact of a Gymnodinium sp Bloom Trial 4 27 Change in Shrimp Weight during Gymnodinium Bloom in System C /30/2013 5/22/ System A System B System C Cysts so abundant that water was gray and they settled into 1-2 mm layer on bottom of a 500 ml flask.

28 Impact of a Gymnodinium sp Bloom 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Change in Red Drum Percent Survival during Gymnodinium Bloom in System C System A System B System C 4/30/2013 5/22/2013 Cysts very abundant on gills. Toxins probably killed the fish.

29 Pfiesteria piscicida a heterotrophic dinoflagellate Pfiesteria may cause fish kills Controversy over mild to severe human health effects Photo by M. Parrow, Center for Applied Aquatic Ecology. PLO counts: 2,655-2,966 cells/ml Fish bioassays (NCSU), Pfiesteria toxin assays (NOAA-HML), PCR (SCDNR) Advanced Technology Environmental Education Center

30 5/2 5/9 5/16 5/23 5/30 6/6 6/13 6/20 6/27 7/4 7/11 7/18 7/25 8/1 8/8 8/15 8/22 8/29 9/5 9/12 9/19 9/26 10/3 10/10 Did Pfiesteria affect Shrimp? /2 5/9 5/16 5/23 5/30 6/6 6/13 6/19 6/26 7/4 7/11 7/18 7/25 8/1 8/8 8/15 8/22 8/29 9/5 9/12 9/19 9/26 10/3 Photo by M. Parrow, Center for Applied Aquatic Ecology. Pfiesteria Bacteria Cyanobacteria Green algae Diatoms Dinoflagellates Pfiesteria, PLOs Heterotrophic protistans Heterotrophic animals Raceway 3

31 Other Problematic Organisms Encountered by Commercial Producers using Indoor, Recirculating, Biofloc Systems: Fusarium solani Vibrio spp. material/ curso19/ ligthner/photo5_2.html Web.mst.edu

32 The dynamic nature of the microbial ecosystem means that these systems are susceptible to changes that impact the Reproducibility Replicability Stability of the suspended biofloc community throughout a growout trial.

33 Prototype Commercial Raceway 235 m 3 raceway

34 Recent Trials Conducted in the Prototype Commercial Raceway Trial # Duration Stocking Size Stocking Growth FCR Survival Harvest Size Production (days) (g) (shrimp/m³) (g/week) (%) (g) (Kg/m 3 ) *

35 Recent Trials Conducted in the Prototype Commercial Raceway Trial # Duration Stocking Size Stocking Growth FCR Survival Harvest Size Production (days) (g) (shrimp/m³) (g/week) (%) (g) (Kg/m 3 ) *

36 Recent Trials Conducted in the Prototype Commercial Raceway Trial # Duration Stocking Size Stocking Growth FCR Survival Harvest Size Production (days) (g) (shrimp/m³) (g/week) (%) (g) (Kg/m 3 ) *

37 Biofloc systems have always outperformed Clearwater systems for shrimp production. New generation of feeds may give equivalent growth rates.? Could Clearwater systems improve replicability, reproducibility, and stability of indoor, superintensive shrimp production?

38 In conclusion, indoor, superintensive Biofloc systems have been successful, but. Challenges: Chemical accumulation with water reuse? Reused water and shrimp growth? Instability of Biofloc Community? Problem microorganisms?

39 Thank you! Acknowledgements The Waddell Mariculture Center Team Deliah Arrington Luis Poersch Heidi Atwood Jacob Richardson Craig Browdy Robert Shumate Matthew Brown Al Stokes Edward DuRant Beth Thomas Jason Haveman Jesus Venero Alisha Lawson Luis Vinatea Brad McAbee Daryl Weldon Kevin Pitts