Cryptic diversity of Ulva (Ulvales, Chlorophyta) in the Great Bay Estuarine System (Atlantic USA): introduced and indigenous distromatic species

Figures & data

Fig. 1. Map of the Great Bay Estuarine System, New Hampshire/Maine, USA, showing locations of 11 study sites (filled circles). Dashed white line indicates border between the two states along the Piscataqua River. Filled stars represent two low salinity estuarine sites where Ulva compressa (tubular form) was reported by Mathieson & Hehre (1986).

Table 1.  Collection sites and distribution of distromatic Ulva taxa within the GBES and on the adjacent open coast.

Site number	Site name	Latitude and longitude	Distance inland (km)	Habitat description	Taxa found ^a
1	Fort Stark	43°03′32″N; 70°42′45″W	0.0	Exposed open coastal site, substratum rocky	UL, UP
2	South Mill Pond	43°04′19″N; 70°45′20″W	4.8	Sheltered pond with tidal restriction, heavily polluted, substratum rocky	UL, UP, UR
3	Dover Point	43°07′07″N; 70°49′42″W	13.8	Mouth of Bellamy River with strong tidal currents, substratum rocky	UL, UP
4	Cedar Point	43°07′42″N; 70°51′13″W	16.3	Rocky substrata, dominant cover of Ascophyllum nodosum (L.) Le Jolis	UR
5	Wagon Hill Farm	43°07′27″N; 70°52′07″W	17.3	Mudflat with mown grass shoreline adjacent to a public swimming area	UC, UR
6	Bunker Creek	43°07′59″N; 70°53′12″W	19.2	Mudflat in calm embayment on Oyster River	UC, UR
7	Adams Point	43°05′43″N; 70°51′08″W	19.7	Narrow strait between Great Bay and Little Bay, substratum muddy with scattered shingle, salt marsh abundant	UL, UP, UC, UR
8	Oyster River	43°07′57″N; 70°54′58″W	22.7	At tidal headwater, substratum muddy, low water clarity, salt marsh and shingle along river bank	UC, UR
9	Lubberland Creek	43°04′30″N; 70°54′12″W	22.4	Mudflat between Vols Island and the mouth of Lubberland Creek	UR
10	Depot Road	43°03′22″N; 70°53′12″W	24.5	Muddy substratum, at Great Bay Discovery Center boat launch	UR
11	Sunset Farm	43°03′24″N; 70°50′03″W	24.8	Mudflat near public golf course, dominant cover of Ulva	UC, UR
	Colony Cove ^b	43°06′54″N; 70°53′53″W	18.3	End of cove in Little Bay, substrata mud, scattered outcrops and shingle, dominant cover of A. nodosum	UC (tube form)
	Crommett Creek ^b	43°05′52″N; 70°52′03″W	22.2	Muddy embayment with limited granitic outcrops and occasional shingle, fringing salt marshes impacted by extensive ice scouring/rafting	UC (tube form)
^a Taxa abbreviations: UL: Ulva lactuca; UP: Ulva pertusa; UC: Ulva compressa; UR: Ulva rigida.
^b Two low salinity estuarine sites where tubular U. compressa were reported by Mathieson & Hehre (1986).

Table 2.  Primers used for ITS sequence amplification and sequencing based upon Blomster et al. (1998) and Hayden et al. (2003)

Sequence	Direction	Primer name	Primer sequence
ITS1	Forward	18S1763	5′-GGTGAACCTGCGGAGGGATCATT-3′
ITS1	Reverse	5.8S142	5′-TATTCCGACGCTGAGGCAG-3′
ITS2	Forward	5.8S30	5′-GCAACGATGAAGAACGCAGC-3′
ITS2	Reverse	ENT26S	5′-GCTTATTGATATGCTTAAGTTCAGCGGGT-3′

Table 3.  GenBank ITS sequences that were identical to ITS sequences of Ulva spp. collected from the GBES.

Species	Source	Accession number
U. lactuca	Tan et al. (1999)	AJ234309
U. pertusa	Shimada et al. (2003)	AB097654
“U. pseudocurvata”^a	Tan et al. (1999)	AJ234312
U. compressa	Tan et al. (1999)	AJ550765
U. scandinavica^b	Shimada et al. (2003)	AB097659
^a Sequence from a specimen identified in GenBank as Ulva pseudocurvata that matched sequences identified as U. compressa. Evidence suggests this specimen was actually a distromatic morphotype of U. compressa (F. Mineur, pers. comm.).
^b Ulva scandinavica and U. rigida are synonyms (Maggs et al., 2007). The GenBank sequences used for comparison with sequences collected in the present study were labeled as U. scandinavica, but U. rigida is the older name so it was used for specimens collected in the present study.

Table 4.  Percent sequence divergences within the ITS regions for the four Ulva taxa found in the GBES. None of the species showed any intraspecific sequence divergence.

	Ulva lactuca	Ulva rigida	Ulva compressa	Ulva pertusa
Ulva lactuca	0	19.5	16	4.8
Ulva rigida	19.5	0	17.4	18.8
Ulva compressa	16	17.4	0	16.1
Ulva pertusa	4.8	18.8	16.1	0

Figs 2–5. Representative blade morphologies of the four Ulva taxa found in the GBES. Fig. 2. Ulva lactuca. Fig. 3. Ulva rigida. Fig. 4. Ulva pertusa. Fig. 5. Ulva compressa. Scale bar: 4 cm.

Figs 6–9. Representative cell morphologies (from fresh material) of the four Ulva taxa found in GBES. Fig. 6. Ulva lactuca Fig. 7. Ulva rigida. Fig. 8. Ulva pertusa. Fig. 9. Ulva compressa. Scale bars: 20 µm.

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