Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Invasive green algae in a western Mediterranean marine protected area: interaction of photophilous sponges with Caulerpa cylindracea.

Abstract

We report on the relationships between some conspicuous Mediterranean photophilous sponge species and Caulerpa cylindracea, a non-indigenous species. A diversification of defense strategies and behavior is highlighted in target species belonging to different orders of Demospongiae from a western Mediterranean Marine Protected Area (NW Sardinian Sea). Caulerpa cylindracea displays a strongly invasive behavior during body colonization of the Irciniidae Sarcotragus spinosulus and Ircinia retidermata (order Dictyoceratida). These sponges possess pre-adaptive defensive morpho-functional and physiological traits enabling them to partly withstand algal invasion. Also Aplysina aerophoba(order Verongiida) seems to be able to control colonization. Successful anti- Caulerpa strategies characterize the rarely affected Crambe crambe (order Poecilosclerida). Species-specific competitive strategies are displayed at different levels of body architecture, behavior and physiology by native sponge species. The invasion patterns on sponges, the invasion dynamics in 2016-2017 and topographic distribution of C. cylindracea on S. spinosulusconfirm this algal species as a threat, with potential long-term effects on sponge assemblages. Data suggest other kinds of poorly investigated synergic stressors affecting these habitat-forming species. Defense strategies of sponge species take the form of: (1) passive deterrence by morpho-functional pre-adaptive traits as growth form, biomass amount, surface traits, and microhabitat within the sponges' aquiferous system; (2) active physiological defense, whereby the morphology/anatomy of the sponge body is adapted to control invaders, by body remodeling and regenerative processes within the aquiferous system and at the sponge surface; (3) presumed active chemical defense by exudation processes of bioactive compounds.