Comparing salinity tolerance in early stages of the sporophytes of a non-indigenous kelp (Undaria pinnatifida) and a native kelp (Saccharina latissima)

Abstract

The short term effects of low salinities on the survival of germlings of an introduced kelp Undaria pinnatifida and a native kelp Saccharina latissima were assessed under laboratory conditions. This experiment was designed to compare the differential stress tolerance to salinity of the early life history stages of sporo phytes of these two kelps that co occur on European Atlantic coasts. Germlings (young sporophytes) of both species were exposed for 4 days to salinities ranging from 31 (control) to 26, 21, 16, 11, and 6 psu. Afterwards, they were post cultured in control seawater (31 psu) for another 4 days to corroborate the viability of injured germlings. Results showed that germlings of the introduced kelp were less resistant to low salinity, surviving to as low as 16 psu; whereas the germlings of the native kelp survived in salinities as low as 11 psu. Despite the observed differences, both species are relatively tolerant to low salinity. Our observations also indicated that, at least in a short term, gametophytes of both species were able to survive in salinities as low as 6 psu. The significance of low salinity tolerance to the distribution of these kelps and for their offshore cultivation is dis cussed.

Multi-decadal decline in cover of giant kelp Macrocystis pyrifera at the southern limit of its Australian range

“…Three consecutive events occurred from 1991− 1995, and individual events occurred in 2002− 2003, 2006. La Niña events oc curred in 1988− 1989− 2012. The events in 1988− 1989−2012 were the strongest.…”

“…Although Busch mann et al (2004) suggested that giant kelp popu lations may have differentiated responses, and in some cases broad tolerance, to variable salinity levels, the majority of literature has investigated this only for salinities lower than typical oceanic concentrations (< 34 ‰; e.g. North et al 1986, Peteiro & Sánchez 2012. While it has been suggested that the salinity changes associated with the EAC are unlikely to be sufficiently large to significantly influence the population dynamics of M. pyrifera in Tasmania (Johnson et al 2011), this may warrant further investigation.…”

The cultivation of European kelp for bioenergy: Site and species selection

“…These may represent locally adapted ecotypes [70]. Young S. latissima sporophytes can survive a four day exposure to 11 psu although significant stress is observed [23], while exposure of only a few days to 5 or 6 psu, results in either a 95% reduction in photosynthetic performance and significant pigment loss, or death [23,68]. In comparison to the others, little is known about S. polyschides.…”

Undaria pinnatifida: A case study to highlight challenges in marine invasion ecology and management

“…Undaria is predominantly found in fully saline conditions, with mean salinities below 27 psu generally limiting its range (Floc'h, Pajot, & Wallentinus, ; Saito, ; Watanabe et al., ). However, laboratory‐based experiments have shown that zoospore attachment may occur at salinities as low as 19 psu, while gametophytes and sporophytes may survive at salinities as low as 6 psu (although below 16 psu sporophytes may start to become damaged) (Bollen et al., ; Peteiro & Sanchez, ; Saito, ). Undaria is viable over a wide range of light regimes; however, changes in irradiance and day length will influence the rate of recruitment, growth, and photosynthesis in both gametophyte and sporophyte stages (Baez et al., ; Choi et al., ; Morelissen, Dudley, Geange, & Phillips, ; Pang & Luning, ).…”

“…Although less defined than the influence of temperature, many abiotic factors can affect the growth and distribution of Undaria, including salinity, light, day length, nutrients, and wave exposure. Undaria is predominantly found in fully saline conditions, with mean salinities below 27 psu generally limiting its range (Floc'h, Pajot, & Wallentinus, 1991;Saito, 1975;Watanabe et al, 2014 (Bollen et al, 2016;Peteiro & Sanchez, 2012;Saito, 1975). Undaria is viable over a wide range of light regimes; however, changes in irradiance and day length will influence the rate of recruitment, growth, and photosynthesis in both gametophyte and sporophyte stages (Baez et al, 2010;Choi et al, 2005;Morelissen, Dudley, Geange, & Phillips, 2013;Pang & Luning, 2004).…”