Table 1.
Correlation of onset of recruitment with March 1 water temperature, 1991–2002
| Species | Mean date of onset | R2 | P | Origin | Date of first collection (ref. 23) |
|---|---|---|---|---|---|
| D. listerianum | July 10 | 0.79 | 0.002 | Bermuda | Late 1980s |
| S. Carolina (23) | |||||
| B. violaceous | June 23 | 0.72 | 0.001 | Japan (24) | Mid-1970s |
| A. aspersa | July 1 | 0.64 | 0.01 | Europe(23) | Mid-1980s |
| Ciona intestinalis | July 15 | 0.01 | 0.87 | Native (25) | — |
| Molgula manhattensis | July 4 | 0.15 | 0.29 | Native (25) | — |
| Botryllus schlosseri | June 13 | 0.27 | 0.10 | Native (25) | — |
Similar results are obtained for correlations between recruitment onset and temperature on April 1 and May 1, suggesting that springtime temperatures determine recruitment onset of invaders. Nonnative species are in bold type.
*
D. listerianum also has been referred to in previously published work as Diplosoma macdonaldi; however, D. listerianum is the appropriate name (G. Lambert, personal communication).
†
B. violaceous in New England also has been referred to as B. diegensis, but recent morphological evidence has confirmed the New England Botrylloides as B. violaceous, most likely native to Japan (see also ref. 24; G. Lambert, personal communication).