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2 September 2020 Nemertean Larval Dispersion Across Biogeographic Provinces of Southwest Atlantic
José E. F. Alfaya, Mariano H. Tonini, Gaspar Soria, Pablo E. Penchaszadeh, Gregorio Bigatti
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Abstract

The nemertean Malacobdella arrokeana is a commensal of the edible giant bivalve Panopea abbreviata; both species have a restricted geographic distribution, high specificity and populations settled along distinct biogeographic provinces. This supposes a high genetic structuring among populations and low intra-populational variability; nevertheless, a lack of genetic structure was detected previously between M. arrokeana populations from the Atlantic Northern Patagonia Gulfs System (NPGS) by means of mitochondrial and nuclear markers. Here, we present a model that explains this lack of genetic structure, integrating larval development and behavior, as well as bio-oceanographical model simulations. We observed in cultured larvae a maximum 30 days of planktonic life before settlement. Planuliform larval morphology and behavior of M. arrokeana suggested that the dispersion is more influenced by passive transport rather than active swimming. Modeling larvae as particles indicated that the limit of biogeographical provinces along the NPGS is not a barrier for dispersal, corroborating that larval dispersion is strictly related to season and to hydrodynamic diffusion patterns present in the area. These results explain the lack of genetic population structure recorded before in the NPGS. Our results provide novel baseline data regarding larval connectivity and oceanographic circulation patterns on the southwestern Atlantic. This information can be used as a reference for the implementation of management plans of invertebrate species with pelagic larvae to ensure the long-term viability of fishery resources shared by different government districts.

© 2020 Zoological Society of Japan
José E. F. Alfaya, Mariano H. Tonini, Gaspar Soria, Pablo E. Penchaszadeh, and Gregorio Bigatti "Nemertean Larval Dispersion Across Biogeographic Provinces of Southwest Atlantic," Zoological Science 37(5), 450-457, (2 September 2020). https://doi.org/10.2108/zs200050
Received: 16 April 2020; Accepted: 14 June 2020; Published: 2 September 2020
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KEYWORDS
connectivity
Lagrangian model simulation
oceanographic fronts
Patagonia
planuliform larval development
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