The effect of temperature on larval development of two non-indigenous poecilogonous polychaetes (Annelida: Spionidae) with implications for life history theory, establishment and range expansion

• Published in: Journal of experimental marine biology and ecology 2014-12, Vol.461, p.20-30
• Main Authors: David, Andrew A., Simon, Carol A.
• Format: Article
• Language: English
• Subjects: Adelphophagy; Animal aquaculture; Animal productions; Annelida; Annelida and closely related phyla: sipuncula. Echiura. Nemertinea; Aquaculture; Biological and medical sciences; Boccardia proboscidea; Fundamental and applied biological sciences. Psychology; General aspects; Haliotis; Invertebrates; Mammalia; Marine; Mollusca; Planktotrophy; Polydora hoplura; Proboscidea; Spionidae; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/j.jembe.2014.07.012

Marine invasions are recognized as an important threat to global biodiversity and predicting the establishment and spread of an introduced species can aid in management efforts to mitigate the damage incurred by these species. In South Africa, the recently introduced polychaete Boccardia proboscidea has been recorded at the outflow of abalone farms where they are known to infest the shells of these mollusks. To determine if B. proboscidea can become established along the South African coast and subsequently expand its range, we assessed brood size, larval size at hatching, larval survivorship and developmental time and rate of this species under temperature regimes reflective of those found along the coast. We also investigated similar temperature dependent development in the well-established non-indigenous shell borer Polydora hoplura which can serve as a proxy for our predictions. Worms were cultured in glass capillary tubes at five different temperature treatments (12°C, 17°C, 21°C, 24°C, 28°C) and planktotrophic and adelphophagic larvae were tracked from oviposition to settlement. We found that in P. hoplura, females producing adelphophagic larvae had smaller broods at the highest temperature treatment and higher temperatures resulted in significantly larger sizes at hatching. Survivorship of planktotrophic and adelphophagic larvae was highest at the intermediate to high temperature treatments (21°C and 24°C) and was generally lower at the lower temperatures (12°C and 17°C). Temperature had no significant effect on brood size of B. proboscidea whereas higher temperatures resulted in larger hatching sizes for planktotrophic and adelphophagic larvae. In B. proboscidea, larval types showed differences in survival optima with planktotrophic larvae exhibiting its highest survivorship at the colder temperatures and lowest at the warmer temperatures while adelphophagic larvae had its highest survivorship at 21°C and its lowest at the extreme temperatures. There was a positive relationship between temperature and developmental rate for both species. The difference in larval sizes of the non-feeding planktotrophic larvae of B. proboscidea was attributed to a growth window that allowed for variability in reproductive traits based on exogenous factors such as temperature. More importantly, the results indicate that B. proboscidea will be capable of producing viable populations at different localities along the South African coast including those where P. hoplura