GENETIC VARIATION AMONG MORPHOLOGICAL FORMS OF PELAGIC

SARGASSUM AND ASSOCIATED HYDROIDS.

AMY N.S. SIUDA1,2, DEBORAH S. GOODWIN2 , JEFFREY M. SCHELL2 , ETHAN ALLEY2, DANA BLOCH2, SHALAGH CANNING2, WALTER HUTCHESON2,

ALESIA HUNTER2, KATHLEEN MCKEEGAN2, KATE PETERSEN2, ROBIN PETERSEN-ROCKNEY2, KATHERINE RUNNING2, LAURA A. COONEY2,

and ANNETTE F GOVINDARAJAN3

10 different morphologies (Winge 1923)2 holopelagic species (Parr 1934)

• S. fluitans (thorns on stem): III , X

• S. natans (smooth stem): I , II , VIII , IX

Schell et al. 2015 Oceanography

RECENT CHANGES IN PELAGIC SARGASSUM DIVERSITY

S. natans

S. fluitans

HISTORICAL SARGASSUM OBSERVATIONS – SEA (1992-2013)

Calder 1995 Bull Mar Sci

© Solvin Zankl

AGLAOPHENIA LATECARINATA – SARGASSUM ASSOCIATION

S. FLUITANS III S. NATANS VIII

SAMPLE COLLECTION

Sample Stations - Sargassum

Sample Stations - Hydroids

S. natans VIIILate Nov 2015

S. natans IApril-May 2015

S. natans VIII &S. fluitans III

Early Dec 2015

S. fluitans IIIFeb 2016

S. natans VIIIS. fluitans IIIMay 2016

S. fluitans IIIApril 2016

SAMPLING LOCATIONS

MOLECULAR METHODS

Sargassum Hydroid# of Samples nSfIII = 14

nSnVIII = 13 nSnI = 15 nSnII = 2

nSfIII = 44nSnVIII = 8 nSnII = 1

Target Genes rbcL-S (chloroplast)mtsp regionMT-CO3

MT-16S rDNAMT-CO1

44 53

• PCR amplification• sequencing and alignment

S. natans VIII genetically indistinct from S. natans I

S. fluitans III distinct from S. natans-complex• 10 polymorphic loci in mtsp• 2 polymorphic loci and a 9 bp indel in rbcL-S

MOLECULAR RESULTSSargassum sp.

MOLECULAR RESULTSAglaophenia latecarinata

S. fluitans IIIS. natans VIII

A-GT-CA-C42 5 32

S. fluitans III

S. natans VIII

S. natans II

Target Genes

MT-16S rDNA

MT-CO1

C-T

T-C

C-T

2

2

1 25

• S. fluitans III sequences distinct from S. natans-complex

S. natans I and S. natans VIII indistinguishable

• A. latecarinata (common hydroid) sequences clustered in two distinct groups according to Sargassum substrate

• reinforces the morphology-driven assertion that S. natans VIII is likely originating from an alternate source region

SUMMARY AND SIGNIFICANCE

We thank the multitudes of SEA Semester students & crew for help with Sargassum collection.

This research was funded by Sea Education Association and

New England Aquarium Marine Conservation Action Fund awarded to Siuda and Govindarajan.