Effects of pco 2 on the fertilization and development of the sea urchin Stronglyocentrotus nudus

Size: px

Start display at page:

Download "Effects of pco 2 on the fertilization and development of the sea urchin Stronglyocentrotus nudus"

Abigail Fletcher
5 years ago
Views:

1 Effects of pco 2 on the fertilization and development of the sea urchin Stronglyocentrotus nudus Young-Gyu Park, Sang-wha Choi, Seong-Gil Kang Korea Ocean R & D Inst., Korea Jung-Suk Lee, Chan-Gyung Sung, Tae-Seob Choi, Seong-Dae Moon, Jong-Hyeon Lee, Kyu-Tae Lee NeoEnBiz Co., Institute of Environmental Safety and Protection, Korea Jin-Hwan Hwang Dept. Civil and Environment Engineering, Dongguk University, Korea Kazuo Inaba, Kokiku Shiba Shimoda Marine Research Center, University of Tsukuba, Japan

2 While testing the toxicity of CO2 on various marine organisms (copepoda, amphipoda, fish etc) living around Korea to assess the possible environmental impact of ocean carbon sequestration, we found a sea urchin that is affected at around 500 ppmv (in a laboratory). This work is supported by Korea Ocean Carbon Sequestration Project funded by the Ministry of Land, Transports, and Maritime Affairs.

3 Previous Studies Kurihara, 2008 The impacts of CO 2 -induced changes in ph on fertilization of sea urchin H. pulcherrimus and E. mathaei were affected when pco 2 was 2000 ppmv (ph<=7.4) (Kurihara and Shirayama, 2004a, b) H. erythrogramma was affected at a much lower level of pco 2 (1000 ppmv, ph ~7.7) (Havenhand et al., 2008) Sensitivity of the fertilization rate to pco 2 may differ widely even among closely related species. Assessment based on one species may not be applicable to other species. Some other species may be even more sensitive to pco 2 than H. erythrogramma. Species with high sensitivity to pco 2 May face an evolutionary threat or extinction within a few decades as pco 2 levels continue to increase.

4 Purpose The effects of pco 2 on the early part of life cycle of the sea urchin Strongylocentrotus nudus Fertilization & development under high pco 2 Sperm motility a species common in Korea a commonly used toxicity test species (Hwang et al., 2009)

5 Bioassay Procedure Filtered seawater CO2 Purging Test Animal Preparation Sperm, egg Exposure Fertilization Rate Embryo Exposure Development Rate

6 Sperm and Egg Preparation KCl Injection for sperm/egg collecting Egg Washing and Dilution

7 Fertilization rate (%) success Optimal dilution rate of sperms S1 S2 S3 S4 S5 0 1/200 1/400 1/800 1/1600 1/3200 Dilution rate Dilution Rate: Either 1/400 or 1/800 Diluted sperms of S. nudus

8 Experiments Date Species pco 2 Level (ppmv) ph Level type EXP-S1 22 Aug Sn 380, 750, 1500, 3000, , 7.79, 7.58, 7.41, 7.20 F, D EXP-S2 29 Sept Sn 380, 550, 750, 1500, 3000, , 7.93, 7.80, 7.60, 7.39, 7.15 F, D EXP-S3 14 Oct Sn 380, 550, 750, , 7.94, 7.84, 7.62 F EXP-S4 1 Sept Sn 380, 450, 550, 750, 1000, , 7.94, 7.91, 7.81, 7.72, 7.55 F EXP-S5 15 Oct Hp 380, 450, 550, 750, 1000, , 7.96, 7.92, 7.78, 7.69, 7.59 F EXP-E1 22 Aug Sn 380, 750, 1500, 3000, , 7.79, 7.58, 7.41, 7.20 F EXP-A1 14 Oct Sn , 7.68, 7.51, 6.96, 6.80, 6.31 F EXP-A2 1 Sept Sn , 7.92, 7.53, 7.16, 6.89, 6.54 F Sn, Strongylocentrotus nudus Hp, Hemicentrotus pulcherrimus EXP-E: egg exposure EXP-A: HCl Type: F (fertilization), D (Development)

9 Sperm exposure (CO 2 ) Fertilization rate is reduced significantly even at about 500 ppmv.

10 Sperm Exposure (HCl vs CO 2 ) The effect of CO 2 induced acidification is much greater than that due to HCl as in other cases (Kurihara 2008). CO2 itself is important.

11 Egg vs Sperm Exposure Sperms show much higher sensitivity. Sperms are responsible for the low fertilization rate.

12 S. nudus vs H. pulcherrimus S. nudus is much more sensitive to pco2 than H. pulchrrimus. We don t know the reason yet.

13 Sperm Motility Inhibitory effects of CO 2 on sperm motility and speed in sea urchins Havenhand et al., 2008; Brokaw, 1977; Brokaw and Simonick, 1976; Cohn, 1918 Is our reduced fertilization rate due to sperm motility? We measured the motility and speed of sperms exposed sea waters of high pco 2 Shimoda Marine Research Center, University of Tsukuba normal abnormal

14 Sperm Motility (S. nudus) Sperm motility was not affected by pco 2 at least within the level we investigated.

15 Sperm Speed (S. nudus) Speed = distance Time Sperm speed was not affected by pco 2 at least within the level we investigated. The low fertilization is due to sperms but not due to the motility.

16 Development Test S. nudus Stages A: fertilized egg B: 8-cell stage C: morula stage D: blastula (before hatching) E: blastula (after hatching) F: gastrula stage G: prism stage H: pluteus stage (Normal Larvae) Exposure Scheme 13 h 72 h A B C D E F G H Full Exposure After Hatching Before Hatching

17 Development Full Exposure After Hatching Before Hatching 2 nd Experiment (Sept. 2008) CO2 Level (ppm) After fertilization, the effect of pco2 became weaker. The group exposed between fertilization and hatching was affected least.

18 Sea Urchin Bioassay under high pco 2 Sperm, Egg Exposure Normal Fertilization [CO 2 ] vs. ph effect Embryo Exposure Development Stronglyocentrotus nudus a species common in Korea a standard toxicity test species Fertilization success rate was recued significantly even at about 500 ppmv Sperm is responsible but not the motility. The effect of CO 2 induced acidification is much greater than that due to HCl. Development success was reduced but lesser degree than the fertilization After hatching the effect became greater. Cause of the low fertilization success rate is not known yet. chemotaxis, acrosome reaction, and binding to the vitelline coat?

19 Discussion laboratory è nature? In the near future, the sea urchin S. nudus may face a threat experienced never before, and could be out-competed by other species. The sea urchin is a calcifier and could also be affected by pco 2 during the larval stage making the threat even more evident. Interspecies variation is large. Some other species may be even more sensitive to oceanic pco 2 than the sea urchin we investigated and face even greater threats of extinction.

MATERIALS AND METHODS

MATERIALS AND METHODS Develop. Growth and Differ. Vol. 21 No. 5 1979 pp. 423-430. CRYOPRESERVATION OF SEA URCHIN EMBRYOS AND SPERM EIZO ASAHINA AND TSUNEO TAKAHASHI Minami 5. Nishi 24 Sapporo 060 Japan and The American National