Osmoregulation in barnacles: An evolutionary perspective of potential mechanisms and future research directions
- 1University of Gothenburg, Sweden
- 2Department of Chemistry and Molecular Biology, University of Gothenburg, Sweden
- 3Department of Biological and Environmental Sciences, University of Gothenburg, Sweden
- 4Department of Marine Sciences, University of Gothenburg, Sweden
- 5IVL - Swedish Environmental Research Institute, Sweden
Barnacles form a globally ubiquitous group of sessile crustaceans that are particularly common in the coastal intertidal. Several barnacle species are described as highly euryhaline and a few species even have the ability to colonize estuarine and brackish habitats below 5 PSU. However, the physiological and/or morphological adaptations that allow barnacles to live at low salinities are poorly understood and current knowledge is largely based on classical eco-physiological studies offering limited insight into the molecular mechanisms. This review provides an overview of available knowledge of salinity tolerance in barnacles and what is currently known about their osmoregulatory strategies. To stimulate future studies on barnacle euryhalinity, we briefly review and compare with known mechanisms of osmoregulation in other marine invertebrates with focus on crustaceans. Different mechanisms are described based on the current understanding of molecular biology and integrative physiology of osmoregulation. We focus on ion and water transport across epithelial cell layers including transport mechanisms across cell membranes and paracellular transfer across tight junctions as well as on the use of intra- and extracellular osmolytes. Based on this current knowledge we discuss the osmoregulatory mechanisms possibly present in barnacles. We further discuss evolutionary consequences of barnacle osmoregulation including invasion success in new habitats and life-history evolution. Tolerance to low salinities may play a crucial role in determining future distributions of barnacles since forthcoming climate-change scenarios predict decreased salinity in shallow coastal areas. Finally, we outline future research directions to identify osmoregulatory tissues, characterize physiological and molecular mechanisms, and explore ecological and evolutionary implications of osmoregulation in barnacles.
Keywords: osmoregulation, Barnacle, Euryhaline, Na-K ATPase, aquaporin, evolution
Received: 08 Mar 2019;
Accepted: 24 Jun 2019.
Edited by:Paivi H. Torkkeli, Dalhousie University, Canada
Reviewed by:Daniel Rittschof, Duke University, United States
Fernando Diaz, Ensenada Center for Scientific Research and Higher Education (CICESE), Mexico
Copyright: © 2019 Blomberg, Sundell, Jonsson and Wrange. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Anders Blomberg, University of Gothenburg, Gothenburg, Sweden, firstname.lastname@example.org