Strong population structure but no equilibrium yet: Genetic connectivity and phylogeography in the kelp Saccharina latissima (Laminariales, Phaeophyta).

Kelp aquaculture is globally developing steadily as human food source, along with other applications. One of the newer crop species is Saccharina latissima, a northern hemisphere kelp inhabiting temperate to arctic rocky shores. To protect and document its natural genetic variation at the onset of this novel aquaculture, as well as increase knowledge on its taxonomy and phylogeography, we collected new genetic data, both nuclear and mitochondrial, and combined it with previous knowledge to estimate genetic connectivity and infer colonization history. Isolation-with-migration coalescent analyses demonstrate that gene flow among the sampled locations is virtually nonexistent. An updated scenario for the origin and colonization history of S. latissima is developed as follows: We propose that the species (or species complex) originated in the northwest Pacific, crossed to the northeast Pacific in the Miocene, and then crossed the Bering Strait after its opening ~5.5 Ma into the Arctic and northeast Atlantic. It subsequently crossed the Atlantic from east to west. During the Pleistocene, it was compressed in the south with evidence for northern refugia in Europe. Postglacial recolonization led to secondary contact in the Canadian Arctic. Saccharina cichorioides is shown to probably belong to the S. latissima species complex and to derive from ancestral populations in the Asian North Pacific. Our novel approach of comparing inferred gene flow based on coalescent analysis versus Wright's island model suggests that equilibrium levels of differentiation have not yet been reached in Europe and, hence, that genetic differentiation is expected to increase further if populations are left undisturbed.

Exploration of the phycoremediation potential of Laminaria digitata towards diflubenzuron, lindane, copper and cadmium in a multitrophic pilot-scale experiment.

The presence of contaminants in aquatic ecosystems can cause serious problems to the environment and marine organisms. This study aims to evaluate the phycoremediation capacity of macroalgae Laminaria digitata for pesticides (diflubenzuron and lindane) and toxic elements (cadmium and copper) in seawater in the presence or absence of mussels. The photosynthetic activity was monitored in the macroalgae to assess its "physiological status". The results showed that the presence of algae decreased diflubenzuron concentration in mussels by 70% after 120 h of exposure. Additionally, this macroalgae was efficient to reduce lindane, Cu and Cd in seawater; even though it not was able to reduce these contaminants in mussels. The studied pollutants did not affect the physiological status of macroalgae. This study reveals that the application of phycoremediation with macroalgae can be an useful and effective mitigation strategy to remove/decrease contaminant levels from the aquatic environment.