|Population dynamics and reproductive patterns of Boltenia echinata (Ascidiacea) on the Swedish west coast|
Svane, I.; Lundälv, T. (1982). Population dynamics and reproductive patterns of Boltenia echinata (Ascidiacea) on the Swedish west coast. Neth. J. Sea Res. 16: 105-118
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
|Authors|| || Top |
Two populations of Boltenia echinata on the Swedish west coast were studied over a 10-year period by stereo-photographic recording of subtidal, vertical rock walls at a depth of 20 m. Supplemental sampling was carried out over a one-year period. One sheltered population decreased in numbers with an explosive increase in Ciona intestinalis. Another, exposed population displayed a similar response at the increase of annual ascidians (Ascidiella scabra, A. aspersa and Corella parallelogramma). Variations in recruitment were influenced by interference competition, while adults were affected to a lesser extent. Recruitment and mortality at the exposed locality were twice as high as at the sheltered locality whereas the mean annual mortality pattern was similar. Adult mortality was related to physical factors ( mainly temperature), imposing stresses of different magnitudes on the two populations. Settling and recruitment was observed throughout the year. No relation was found between the presence of incubating embryos or larvae in the atrial cavity and settling.