Table 1.

Sampling locations for biogeographic comparison across North American Atlantic Coast

Region	Site ID	Location	Location notes	Latitude	Longitude	Primary substratum	Eggs	Sperm
Florida	CML	St Teresa	FSU Coastal and Marine Laboratory	29.91506	−84.5082	Sedimentary cobble on protected sandy beach	Y	Y*
	WAK	Wakulla County	Wakulla Beach	30.10236	−84.25895	Oyster beds	Y*	Y*
Georgia	STS	St. Simon Island	King’s Beach	31.13334	−81.39427	Breakwater rocks	Y*	Y
	JEK	Jekyll Island	Fishing Pier	31.11761	−81.4165	Isolated dead trees/driftwood	Y	Y
Virginia	RBB	Birdsnest	Red Bank boat ramp	37.44566	−75.83993	Wooden pier beams	Y	Y
	QBY	Quinby	Quinby Harbor	37.55274	−75.7291	Rotten wood posts in salt marsh	Y*	Y
Massachusetts	NAH	Nahant	No Name Point	42.41977	−70.90338	Submerged in rock pools	Y*	Y*
	PMH	Nahant	Pumphouse Beach	42.41729	−70.90528	Submerged in rock pools	N	Y*

All samples collected between June and July 2016 by WHR. See Ryan and Miller (2019) for additional site details. Eggs/sperm columns indicate sites where fertile individuals bearing each gamete type have been found, either during the 2016 transect sampling (Y) or during another sampling in the same area before or since (Y*).