Stress tolerance of the invasive macroalgae Codium fragile and Gracilaria vermiculophylla in a soft-bottom turbid lagoon

Abstract

Invasive species are often hypothesized to have superior performance traits. We compared stress tolerance (as change in biomass) of the invasive macroalgae Codium fragile ssp. tomentosoides and Gracilaria vermiculophylla to the native macroalgae Fucus vesiculosus, Agardhiella subulata, Hypnea musciformis and Ulva curvata in Hog Island Bay, a shallow lagoon in Virginia, USA. We hypothesized that the success of the two aliens is due to their high tolerances of turbidity, sedimentation, desiccation, grazing and nutrient enrichment. Like many lagoons, Hog Island Bay is characterized by extensive intertidal mudflats, high turbidity and sedimentation, and high densities of omnivorous mud snails. Nutrient enrichment may also become a problem as land use practices in adjacent watersheds change. Contrary to our hypothesis, C. fragile was less resistant to sedimentation, desiccation and grazing than other algae and had low growth at all light and nutrient levels. This suggests that any superior performance of this invasive species compared to native algae is probably limited to microhabitats where stress is minimal and where bivalve shells facilitate recruitment and long-term persistence. In contrast, G. vermiculophylla was resistant to desiccation, burial and grazing, and was not negatively influenced by either high or low light or nutrient levels. These traits reflect the current success of G. vermiculophylla in already invaded lagoons and estuaries, and indicates that it will likely continue its spread in European and North American turbid and tidal soft-sediment systems

Temperature- and light-dependent growth and metabolism of the invasive red algaeGracilaria vermiculophylla– a comparison with two native macroalgae

“…Our laboratory experiments suggest that G. vermiculophylla shares common traits with both the slowgrowing, leathery F. vesiculosus, which can be classified as a K-strategist, and the fast-growing, sheetforming U. lactuca, which can be regarded as an r-strategist (Littler & Littler, 1980;Thomsen & McGlathery, 2007). When comparing temperature dependencies, G. vermiculophylla had an almost identical, but marginally weaker response to higher temperatures than U. lactuca; this was observed for somatic growth, photosynthesis and respiration.…”

“…To understand which environmental conditions control survival and growth, and thus the potential geographical distribution of G. vermiculophylla, studies have tested for the effects of stable (Rueness, 2005; and fluctuating salinities, local grazing (Nejrup & Pedersen, 2010; and nutrients Thomsen & McGlathery, 2007;Nejrup & Pedersen, 2010;Abreu et al, 2011), and tolerances to sediment load and desiccation stress (Thomsen & McGlathery, 2007). However, it remains unclear why G. vermiculophylla has an advantage compared to native species of macroalgae in the shallow estuaries of Scandinavia.…”

Growth and biomass development of the introduced red alga Gracilaria vermiculophylla is unaffected by nutrient limitation and grazing

“…300-fold higher in eutrophic Holckenhavn Fjord than in the more nutrientpoor Fyns Hoved, although G. vermicu- , corresponding to a doubling time of 8 to 10 d), which is equal to in situ rates reported from Kiel Bight, Germany (Weinberger et al 2008), and from Hog Island Bay, Virginia, USA (Thomsen & McGlathery 2007). Growth rates were similar in Holckenhavn Fjord and Fyns Hoved, and the seasonal patterns of growth followed temporal changes in incident light and water temperature rather than variations in nutrient concentrations.…”

“…Yokoya et al 1999, Raikar et al 2001). Yet, in situ growth and biomass development as well as the regulation of these parameters have received less attention (but see Thomsen & McGlathery 2007, Weinberger et al 2008 Gracilaria vermiculophylla grows fast under optimal culture conditions (i.e. 0.1 d -1…”

Stress levels over time in the introduced ascidian Styela plicata: the effects of temperature and salinity variations on hsp70 gene expression

“…Only those organisms adapted to wide environmental fluctuations can survive in the long term, successfully colonizing these habitats [e.g., the polychaete Nereis diversicolor (Paramor and Hughes 2004;Aberson et al 2011) and the limpet Crepidula fornicata (Blanchard 1997;Bishop 2005)]. In order to cope with sharp abiotic changes that can yield suboptimal and stressful conditions, successfully introduced species should be equipped with efficient physiological mechanisms to respond to stress (Thomsen and McGlathery 2007;Piola and Johnston 2008;Dafforn et al 2009). …”