2019 YSLME

The Origin, Genetic Makeup, and Population Dynamics of the Golden Tide Seaweeds Sargassum horneri in

Seo Yeon Byeon1, Sangil Kim2, Sang Rul Park3*, Hyuk Je Lee1*

1Molecular Ecology & Evolution Lab, Dept. Biological Science, Sangji University 2Oceanic Climate & Ecology Research Division, National Institute of Fisheries Science 3Estuarine & Coastal Ecology Lab, Dept. Marine Life Sciences, Jeju National University Drifting Seaweeds

Green tides

Brittany, France Qingdao beach, China

Golden tides

Antigua, southern Caribbean Sierra Leone, Africa

Smetacek et al. (2013) Sargassum Golden Tides

Seogwipo, Jeju Island Ihoteu beach, Jeju Island l Drifting Sargassum during winter to spring with large biomass l Accumulating along the southern coastlines of Korea l Intensified recently in frequency, range, and magnitude Negative Impacts of Golden Tides

Haenam-gun, Jeollanam-do Sinan-gun, Jeollanam-do (Hwang et al. 2016) l Destruction of aquaculture & fishery industries l Collapse of local tourism owing to rotting seaweeds l Destruction of coastal ecosystems But, Positive Effects of Sargassum horneri

Munseom, Jeju Island

l Kelp forest formation, serving as spawning & nursery grounds

l An important role in ecosystem functioning and services

l Wide distribution in the northwestern Pacific Some Recent Genetic Studies

Su et al. (2017)

Liu et al. (2018) Research Objectives

l To trace the geographic or genetic origins of floating Sargassum horneri populations in Korean waters

l To examine differences in the genetic structure between floating and Korean benthic populations

l To investigate population dynamics, including density, mortality, biomass, and growth rate of two Korean benthic populations Sampling Localities

118°E 122°E 126°E 130°E (A) HN Floating 40°N St.1 N=14 (2015~2018) East Sea/ St.3 Korea Sea of Benthic DSP N=5 36°N St.2 (2015~2016) West Sea/ DBP SA 311 SA YS WS 312 St.4 (Line) A 1km 남해 정선 JJWS B SSL 제주 서남 조사 314 Japan (B) 해역 YDA JJP 32°N ECS SS China HJ Jeju Island

SGP

East China Sea MS 28°N 200km 10km Data Analyses

l Molecular markers for genetic analyses

• Mitochondria DNA (mtDNA) Cox3 (Hu et al. 2011) • Seven nuclear microsatellites (Shan et al. 2015)

l Population parameter estimates

• Two benthic populations: Munseom on Jeju Island (open area), Jindo on the South Sea (closed area) • 0.25 m2 plot (N= 4~7) at 5 m of water depth • Density, mortality, biomass, and growth rate MtDNA Cox3 Haplotype Distribution

Haploype 1 Haploype 2 Haploype 3

120°E 126°E 130°E 136°E

25-30 (A)

10-15 40°N 3-8 N

HN1 HN3 38°N Korea DSP HN2 36°N WS DBP SA Japan YS HN4

34°N A 1km JJSW B SSL (B) YDA SS JJP China 32°N HJ ECS Jeju Island 30°N Kuroshio Current

28°N SGP MS 200km 10km Byeon et al. (2019) Scientific Reports Haplotype Distribution in the northwestern Pacific

Haploype 1 = H7 H7 Distributed in Zhoushan, Zhejiang in East China

Hu et al. (2011) (A)

HN1 HN3

Korea HN2 Haploype 1 DSP

WS DBP HN4 SA Japan 1km YS (B) YDA SS JJP A SSL HJ JJSW B Jeju Island China

ECS

SGP 200km 10km MS Haplotype Distribution in the northwestern Pacific

Haploype 2 = H39 H39 Distributed in Aomori, Shiriyazaki in Japan

(Hu et al. 2011) (A)

HN1 HN3 Haploype 2 Korea HN2 DSP

WS DBP HN4 SA Japan 1km YS (B) YDA SS JJP A SSL HJ JJSW B Jeju Island China

ECS

SGP 200km 10km MS The Origin of Floating Populations

(A)

HN1 HN3

Korea DSP HN2

WS DBP SA Japan YS HN4 A 1km SSL JJSW B (B) YDA SS JJP China HJ ECS Jeju Island

0Kuroshio Zhoushan Current SGP 200km 10km MS Populations from Zhoushan: genetic sources of floating samples

Byeon et al. (2019) Scientific Reports Population Genetic Structure All populations K=1~19 : K=2 1.00

0.80

0.60

0.40

0.20

0.00

Floating populations Benthic populations Floating populations Benthic populations K=1~14 : K=3 K=1~5 : K=4 1.00

0.80

0.60

0.40

0.20

0.00

Distinct genetic structure between floating and benthic populations

Byeon et al. (2019) Scientific Reports Phylogenetic Relationships

Floating and benthic populations showing distinct phylogenetic clusters except for the KF17a-3 sample

Byeon et al. (2019) Scientific Reports Temporal Structure in Floating Populations

Group 1 Group 2 Group 3 Group 4 Group 5 (2015.02) (2016.03) (2017.02) (2017.04~05) (2017.12~ CF17a 2018.01) KF16-1 KF15 CF17 KF17a-1,2,3,4 KF16-2 KF17b-1 KF17 KF17a-5 KF17b-2 KF17a-6

AMOVA (Analysis of Percentage Fixation df P-value Molecular Variance) variation indices

Among temporal groups 4 9.64 FCT = 0.10 0.19 Among populations within 8 20.80 F = 0.23 < 0.001 temporal groups SC

Within populations 425 69.55 FST = 0.30 < 0.001

More genetic variation within floating populations from the same sampling periods than from different periods

Byeon et al. (2019) Scientific Reports Density

150 150

) Munseom ) Jindo -2 -2 120 120

90 90

60 60

30 30 Density (individuals m (individuals Density m (individuals Density 0 0 N D J F M A M J J A S O N D J F M A M J J 2017 2018 2017 2018 l A maximum density of 116 and 75 m-2 individuals at Munseom and Jindo l The density gradually declining during the study period and completely disappearing in July Mortality

50 50 ) ) Munseom Jindo -2 -2 100 100 40 40 80 80 30 30 60 60

20 20 40 40 Mortality rate (%) rate Mortality 10 20 (%) rate Mortality 10 20 Mortality (individuals m (individuals Mortality Mortality (individuals m (individuals Mortality 0 0 0 0 N D J F M A M J J N D J F M A M J J 2017 2018 2017 2018 l For Munseom, the highest mortality during 2-3 months following recruitments l However, for the Jindo population, most individuals dying off in July when water temperature increasing Biomass

1000 1000 ) ) -2 Munseom -2 Jindo Standing stock 800 Detached 800

600 600

400 400

200 200 Biomass (g dry weight m (g dry Biomass 0 weight m (g dry Biomass 0 N D J F M A M J J N D J F M A M J J 2017 2018 2017 2018 l The greatest amount of detached biomass at January, March and May- June for Munseom, while its gradual increase for Jindo l Approximately 200 g and 150 g DW m-2 of maximum detached biomass for Munseom and Jindo, respectively Growth Rate

15 6 15 6 Munseom Jindo 5 5 ) ) 12 12 -1 -1 4 4 9 9 3 3 6 6 2 2 Growth (%) rate Growth (%) rate Growth day (cm Growth day (cm 3 3 1 1

0 0 0 0 N D J F M A M J J N D J F M A M J J 2017 2018 2017 2018 l Higher growth rate for Munseom than for Jindo population l For Munseom, 12 cm and 5% per day of maximum growth and growth rate in February and December, but a constant and low growth rate for the Jindo population Conclusions l Floating populations in Korean waters were likely to be originated from Zhoushan region on China’s east coast l Floating populations were clearly genetically different from Korean benthic populations l Some genetic differentiation was detected within floating populations from the same sampling periods l Patterns of population dynamics considerably differed between two Korean benthic populations from Jeju Island and the South sea On-going Research

l More detailed assessments of the genetic structure for Korean benthic populations l Continuous genetic monitoring of floating samples from Korean waters as well as from the l Application of our developed indel and SNP markers for discriminating between floating and benthic samples l Ecological monitoring of Korean benthic populations Acknowledgements Thank you for your attention!