Differential toxic effects of Ulva lactuca (Chlorophyta) on the herbivorous gastropods, Littorina littorea and L. obtusata (Mollusca)

Abstract

Members of the genus Ulva are widespread and abundant in intertidal and shallow subtidal areas but there are conflicting data regarding susceptibility to herbivory. While some studies have documented that Ulva spp. were favored by a diversity of marine herbivores, other work has revealed herbivore deterrence. We investigated grazing and growth rates of the littorinid species, Littorina littorea and L. obtusata, when offered Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, and Chondrus crispus, highlighting distinctive vulnerabilities to toxic effects of U. lactuca. Ulva lactuca was the preferred food of L. littorea, while L. obtusata showed no grazing on this ephemeral algal species. In contrast, F. vesiculosus was highly preferred by L. obtusata. Although L. littorea demonstrated a grazing preference for U. lactuca, growth rate of this gastropod species was nearly 3× greater when fed F. vesiculosus, suggesting a non-lethal, negative effect of U. lactuca on L. littorea with long-term exposure. Mortality of L. obtusata ranged from 0% to 100% when held in the presence of various Ulva densities for 1 week, and Ulva exudate depressed herbivory of this gastropod. We conclude that the water-soluble, toxic exudate produced by U. lactuca in response to herbivory had allelochemical properties, and may contain a cleavage product (acrylic acid) of dimethylsulfoniopropionate or reactive oxygen species (i.e., H O ). Observed differences in susceptibility to Ulva toxicity by the littorinid species may be related to generalist versus specialist feeding and habitat strategies.

Impacts of The Invasive Seaweed <em>Asparagopsis armata</em> Exudate on Rockpool Invertebrates

“…obtusata (Peckol & Putnam, 2017). The present study shows the potential of A. armata Regarding effects on G. umbilicalis, A. armata induced a significant increase in total lipids, along with decreased activities of LDH and ETS.…”

Bloom-forming macroalgae (Ulva spp.) inhibit the growth of co-occurring macroalgae and decrease eastern oyster larval survival

“…While green macroalgae have been traditionally thought of as non-toxic, increasing evidence has shown that species of ulvoid macroalgae can inhibit co-occurring phytoplankton (Nan et al 2008;Tang & Gobler 2011), macroalgae (Gao et al 2014), and invertebrates (Nelson & Gregg 2013, Van Alstyne et al 2014, Peckol & Putnam 2017.…”

Diet-dependent gene expression highlights the importance of Cytochrome P450 in detoxification of algal secondary metabolites in a marine isopod

“…Interestingly, all of the CYP2 transcripts were more highly expressed in I. balthica fed with U. lactuca than in isopods fed with F. vesiculosus . Several recent studies have shown that Ulva produces a range of secondary metabolites which deter both gastropods 18 and sea urchins 39 . F. vesiculosus also possesses a range of secondary metabolites, but as F. vesiculosus is the natural diet of I. balthica , we can speculate that they might be able to detoxify F. vesiculosus compounds through a separate, taxon-specific, pathway.…”

“…In common periwinkles ( Littorina spp. ), a recent study found that the deterrence effects of Ulva lactuca were species-specific, which the authors hypothesized could be due to differences in feeding strategies (generalist vs specialist) 18 .…”