Temperature requirements for the growth of young sporophytes of Undaria pinnatifida and Undaria undarioides (Laminariales, Phaeophyceae)

Abstract

The relative growth rate of young sporophytes of Undaria pinnatifida (Harvey) Suringar and Undaria undarioides (Yendo) Okamura was examined in order to understand the difference in distribution of these two species around the coast of Japan. The optimal temperature for growth of both species was similar at 20 ° C and the upper critical temperature for growth was also similar, at 27 ° C for U. pinnatifida and 26 ° C for U. undarioides . Therefore, the optimal and upper critical temperatures for growth of the young sporophytes are not the main factors determining the distribution of each species. Next, the lower critical temperatures for growth were examined. For the young sporophytes of U. pinnatifida , the lower limit was less than 5 ° C while for those of U. undarioides it was 15 ° C. Thus, the difference in the lower critical temperature for growth between the two species was approximately 10 ° C. During the period of young sporophyte growth in the field, the temperature at the mouth of Ise Bay, Japan, where U. pinnatifida occurs, ranges from 12.7 ° C in December to 13.1 ° C in April, with a minimum of 7.9 ° C in February. Our experiments indicate that young sporophytes are able to grow throughout this period. The temperature off Hamajima, Japan, where U. undarioides occurs, ranges from 19.1 ° C to 14.8 ° C during the same time period. Again, young sporophytes are able to growth throughout this period, although minimum winter temperatures are only just high enough for growth. These natural temperature ranges during the growth season of the sporophytes agree well with the experimentally determined temperature requirements for growth of each species. Therefore, the difference between the two species in the critical temperature required for growth of the young sporophytes, especially in the low temperature range, is one of the major factors determining the distribution pattern of each species.

Extreme Marine Heatwaves Alter Kelp Forest Community Near Its Equatorward Distribution Limit

“…In 2013, both species appeared during monitoring surveys at the protected side of the three islands, but were absent from the exposed sides (our study sites) (Montaño-Moctezuma et al, 2014). U. pinnatifida is an opportunistic cosmopolitan invasive species (Lowe et al, 2000) able to tolerate a wide range of temperatures (Morita et al, 2003), allowing this species to colonize empty spaces left by canopyforming kelps. Nevertheless, without disturbance, U. pinnatifida rarely establishes under a dense canopy (Valentine and Johnson, 2003;.…”

Thermal traits for reproduction and recruitment differ between Arctic and Atlantic kelp Laminaria digitata

“…Gametophytes are the most thermally tolerant life cycle stage in kelps, withstanding higher seawater temperatures than sporophytes [27,30,47,49,50], but upper survival temperature depends on exposure time. The gametophytes of L. digitata from Helgoland (North Sea) are able to survive 28˚C for 1 day, 26˚C for 2 days, but this limit already decreases to 24˚C after 7 days and to 23˚C after 4 weeks, thereafter being stable [30].…”

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

“…The ability to tolerate this large annual range is due to the survival of microscopic gametophyte and sporophyte stages which can persist at temperatures between −1 and 30°C (Morita, Kurashima, & Maegawa, 2003a;Saito, 1975). Sporophyte growth has a slightly more restricted temperature range of 0-27°C; optimum growth rate is site-specific, however, which tends to fall within 5-20°C, and senescence may be induced by exposure to temperatures at or above 24°C (Bollen, Pilditch, Battershill, & Bischof, 2016;Henkel & Hofmann, 2008;James & Shears, 2016a;Morita, Kurashima, & Maegawa, 2003b;Saito, 1975;Skriptsova et al, 2004). The reproductive sporophylls can be present between 5 and 27°C, and when mature, spore release and settlement occur between approximately 11-25°C (James & Shears, 2016b;Saito, 1975;Skriptsova et al, 2004;Thornber, Kinlnan, Graham, & Stachowicz, 2004).…”