Effects of Ocean Acidification and Warming on the Development and Survival of Homarus americanus Larvae

Darcia Gonzalez¹´², Sarah Caron¹, Devin Domeyer¹, Jesica Waller¹, David Fields¹1Bigelow Laboratory for Ocean Sciences, East Boothbay, ME

2 University of Texas Rio Grande Valley, Edinburg, TX

Abstract Methods

Results

Conclusions

The goal of this experiment was to study the carapace length, mass, survival and overall development of American lobsters (Homarus americanus) from southern New England under predicted end-century pCO₂s and temperatures. The American lobster comprises one of New England’s most valued marine fisheries, but we do not yet know how changing oceanic conditions will affect the lobster during its four larval stages. A series of four measurements were conducted in order to test the potential interactive effects of higher temperatures and pCO₂ levels. The parameters that were analyzed included survival, dry weight, carapace length as well as Carbon and Nitrogen mass of these larvae. We found that both higher pCO₂ and higher temperatures had no significant effect on the length and mass of American lobster larvae. This provides indication that larvae from the southern extent of the lobster’s geographic range may be resilient to predicted end-century increases in pCO2 and temperatures.

• Temperature, pH and salinity was measured daily.• Survival was measured by estimating the percent of larvae alive in

each tank every other day.• Dry weights were recorded 48 hours after lobster larvae began a new

stage.• Carapace length was measured using ImageJ, a photo analyzing

software.• Carbon and Nitrogen were measured at Bigelow Analytical Services.• Water chemistry was monitored on a weekly basis. Two samples were

obtained from each treatment. One was used for spectrometric pH measurements while the other was used for total alkalinity.

• Carbonate chemistry was calculated using CO2SYS.• 3 way ANOVAS were done to analyze the effect of pCO2 and

temperature treatment on carapace length and dry weight.

• These measurements are a portion of a larger experiment where the respiration rates as well as swimming speeds were also studied.

• Larvae raised at end-century temperatures in all pCO₂ treatments had slightly decreased survival.

• Overall, our results suggest that rising pCO₂ and temperatures have no significant effects on the growth and development on H. americanus larvae.

• A similar study of H. americanus larvae from the mid-coast region found that increased pCO₂ levels (1200 ppm) reduced the carapace length of larvae(1) . This provides indication that larvae from the southern extent of the lobster’s geographic range may be resistant to predicted end-century increases in pCO2 and temperatures.

Acknowledgments: Support for this project was provided by NSF Grant #1460861 REU Site: Bigelow Laboratory of Ocean Sciences – Undergraduate Research Experience in the Gulf of Maine and the World Ocean, Bigelow Analytical Services. Thanks to Craig Burnell and the University of Maine Darling Marine Center.

Research Question: Can increases in ocean temperature and rising pCO₂ levels affect how Homarus americanus larvae develop?

Figure 4. Results showing carapace length averages by stage for each treatment with standard deviation.

Figure 3. Results showing average dry weights of lobster larvae per stage for each treatment with standard deviation.

Figure 5. a) Preliminary graph providing a slope based off of observed data points on larval survival (this graphis an example of just one treatment consisting of duplicated tanks). b.) Final graph showing logarithmicsurvival slopes for each treatment.

Table 2. Water chemistry over the experimental period. Both pH and alkalinity were measured on the total scale.

Table 1. Experimental design shows 4 tanks for each treatment for a total of 12 tanks. This was replicated giving a total of 24 tanks.

Figure 1. a) Global ocean surface pH.

Figure 2. Four different lobster larval stages and their distinct appendages.

IPCC 2013.

References:1. Keppel, E. A., Scrosati, R. A., & Courtenay, S. C. (2012). Ocean acidification decreases growth and development in American lobster (Homarus americanus) larvae. J. Northw. Atl. Fish. Sci, 44, 61-66.2. IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge, UK and New York, NY, USA.3. Fogarty, M. J. (1983). Distribution and relative abundance of American lobster, Homarus americanus, larvae: a review. NOAA technical report NMFS SSRF United States. National Marine Fisheries Service.

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PCO2 Input (ppm) 400 750 1200 400 750 1200

Temperature (°C) 16.3 ± 0.12 16.6 ± 0.21 16.5 ± 0.23 19.2 ± 0.40 18.3 ± 0.12 18.5 ± 0.40

Salinity 34.7 ± 0.58 34 ± 1 34.7 ± 0.58 35 ± 0 34.3 ± 0.58 35 ± 0

pHT 8.17 ± 0.15 8.01 ± 0.01 7.86 ± 0.03 8.18 ± 0.07 8.08 ± 0.03 7.91 ± 0.03

AT (µEq kg-1) 2,172.18 ± 13.57 2,190 ± 42.64 2,108 ± 65.97 2,183 ± 39.07 2,190 ± 36.42 2,180 ± 10.36

PCO2 (ppm) 267 ± 9 405 ± 16 558 ± 41 260 ± 52 338 ± 19 510 ± 36

HCO3- (µmol kg-1) 1,885 ± 11 1,985 ± 42 1,959 ± 64 1,883 ± 16 1,950 ± 30 2,008 ± 2

CO32- (µmol kg-1) 111 ± 4.6 80 ± 3.6 57 ± 4.1 117 ± 16.8 93 ± 5.6 66 ± 4.8

Ωcal 2.68 ± 0.1 1.94 ± 0.1 1.39 ± 0.1 2.80 ± 0.4 2.25 ± 0.1 1.60 ± 0.1

Ωarag 1.68 ± 0.07 1.22 ± 0.05 0.87 ± 0.06 1.76 ± 0.25 1.41 ± 0.09 1.01 ± 0.07

b.

a.

a.b.

Figure 6. a) Stage 4 Lobster larval carbon mass.

Figure 6. b) Lobster larval nitrogen mass.

b.

a.

b) Conceptual schematic of predicted global average surface temperature change.

1950 2000 2050 2100

Ocean Acidification and Warming

In order to test if global warming and ocean acidification willaffect the American Lobster, we examined growth anddevelopment across the four distinct larval stages. We usedthree different pCO₂ levels as well as two temperatures that theIntergovernmental Panel on Climate Change (IPCC) haspredicted for the end of century. It is unknown how lobsters willrespond to changes in carbonate chemistry and temperature.

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