LOCAL ADAPTATION OF CERAMIUM TENUICORNE (CERAMIALES, RHODOPHYTA) WITHIN THE BALTIC SEA¹

Abstract

Ceramium tenuicorne (Kützing) Waern is a red alga that is widely distributed in the brackish Baltic Sea. We studied the growth response of Ceramium to low salinity and nutrient enrichment, using isolades from two regions of the Baltic Sea where the alga approaches its inner distribution limit. Ecotypic differentiation was observed in that differences in growth response among isolates corresponded to salinity conditions in their regions of origin. Isolates from the Gulf of Bothnia (4 psu) had inherently lower growth rates that were not increased when transferred to higher salinity, but were better adapted to very low salinity levels than isolates from the Baltic Proper (7 psu). Further, the results indicate that Ceramium from different regions of the Baltic Sea vary in their responses to nutrient enrichment. The observed differences may be best described as a quantitative difference in the proportion of isolates with hyposaline adaptation. The results indicate that the wide distribution of Ceramium in the Baltic Sea is better explained by the occurrence of locally adapted genotypes than by a generalist life strategy, and provide example of adaptive differentiation in a marine edge environment.

Algal Bioremediation of Waste Waters from Land-Based Aquaculture Using Ulva: Selecting Target Species and Strains

“…Over large spatial scales (e.g., ocean wide) there is evidence both for [19], [21] and against [25] local adaptation of macroalgae. Likewise, over small spatial scales results are mixed with evidence for local adaptation over 100 s of kilometres [26] and two out of three populations showing evidence of local adaptation across intertidal zones [20]. The superior performance of local strains under temperatures corresponding to local conditions in the current study implies that strains of U. ohnoi are adapted to local temperatures to some extent.…”

“…However, across all temperature treatments Townsville strains of U. ohnoi had the highest growth rates and Sydney strains had the lowest growth rates. Similarly, superior performance of a single “strain” across multiple habitat types or conditions has been reported for the red alga Ceramium tenuicorne [26] and the aquatic plant Potamogeton pectinatus [23]. Accordingly, it should not be assumed that growth rates will be highest in strains sourced from local environments and there may be selective pressure in local environments for traits other than growth and temperature tolerance.…”

“…Based on these results, we would expect local strains of algae to have higher growth, and therefore bioremediation capability, in their local habitats compared to non-local strains. However, experimental studies have not always found that local strains are superior under local environmental conditions [22]–[26]. Therefore, assessing the performance of strains sourced from multiple locations under a range of environmental conditions is important in the selection of target species for algal bioremediation.…”

Linking nutrient loading, local abiotic variables, richness and biomasses of macrophytes, and associated invertebrate species in the north-eastern Baltic Sea

“…On the other hand, C. tenuicorne benefitted only from the gulf-scale phosphorus loading whereas the species was actually negatively affected by the gulf-scale nitrogen loading. Although salinity conditions do not vary largely in our study area, it has been shown that the growth rate of C. tenuicorne is a function of salinity and nutrients, and in different regions the species responds differently to nutrient loads (Bergström and Kautsky, 2006). This may explain the opposing effects of nitrogen and phosphorus to this red algal species.…”

Investigations on Reproductive Affinities in Red Algae

“…Physiological differentiation is observed in Ceramium tenuicorne from the Skagerrak-Baltic region: the isolates from low and high salinity sites showed different growth responses in different salinities, which corresponded to the salinity regimes of their original habitats, and their hybrid indicated an intermediate pattern relative to that of the parents (Rueness, 1978;Rueness and Kornfeldt, 1992;Bergström and Kautsky, 2006). Bergström et al (2003) observed a strong reduction in sexual reproduction and an increased tetrasporophyte dominance along the salinity gradient in C. tenuicorne from its inner distribution limit in the Baltic Sea.…”