Prevalence and Mechanisms of Dynamic Chemical Defenses in Tropical Sponges

Abstract

Sponges and other sessile invertebrates are lacking behavioural escape or defense mechanisms and rely therefore on morphological or chemical defenses. Studies from terrestrial systems and marine algae demonstrated facultative defenses like induction and activation to be common, suggesting that sessile marine organisms also evolved mechanisms to increase the efficiency of their chemical defense. However, inducible defenses in sponges have not been investigated so far and studies on activated defenses are rare. We investigated whether tropical sponge species induce defenses in response to artificial predation and whether wounding triggers defense activation. Additionally, we tested if these mechanisms are also used to boost antimicrobial activity to avoid bacterial infection. Laboratory experiments with eight pacific sponge species showed that 87% of the tested species were chemically defended. Two species, Stylissa massa and Melophlus sarasinorum, induced defenses in response to simulated predation, which is the first demonstration of induced antipredatory defenses in marine sponges. One species, M. sarasinorum, also showed activated defense in response to wounding. Interestingly, 50% of the tested sponge species demonstrated induced antimicrobial defense. Simulated predation increased the antimicrobial defenses in Aplysinella sp., Cacospongia sp., M. sarasinorum, and S. massa. Our results suggest that wounding selects for induced antimicrobial defenses to protect sponges from pathogens that could otherwise invade the sponge tissue via feeding scars.

Chemical Composition, Antimicrobial, Cytotoxic and Antiplasmodial Activities of Three Sponges from Buton Islands, Indonesia

“…Sponges (phylum Porifera), constitute one of the most primitive of multicellular animals (Metazoa) and play important to the overall ecology of coral reefs. Natural products chemists have been isolating bioactive lead compounds from sponges and commonly described as chemical defense tools to protect against a predator (Burns et al, 2003;Rohde et al, 2015). Sponges have continuously been an important part of Indonesian coral reef communities.…”

Secondary Metabolites of Marine Microbes: From Natural Products Chemistry to Chemical Ecology

“…Until today, the number of marine species that inhabit the world's oceans is not truly known; however, experts estimated a number approaching 1-2 million species (Simmons et al 2005;Das et al 2006). In the past, marine sponges were an interesting source for novel NPs; these sessile organisms can produce bioactive substances for chemical defense against natural predators, such as fishes (Rohde et al 2015), as well as prevent overgrowth by competing organisms (Proksch 1994;Ortlepp et al 2006). Furthermore, sponges serve as incubators for particular associated microorganisms like bacteria and fungi that also can contribute to the production of bioactive compounds (Radjasa et al 2011;Wiese et al 2011).…”

“…As a result, survival and reproduction between the competing organisms can strongly depend on their ability to produce bioactive SMs (de Carvalho and Fernandes 2010). These bioactive substances can perform various tasks for their producers and associated organisms; for instance, SMs work as a chemical defense against predators (Pohnert 2004;Kubicek et al 2011;Rasher et al 2013;Rohde et al 2015;Helber et al 2017), function as attractants toward consumers (Sakata 1989), have antimicrobial effects against pathogenic microbes (Goecke et al 2010;Puglisi et al 2014;Helber et al 2018), guide the opposing sex by letting individuals find and evaluate potential mating partners through chemical cues (Lonsdale et al 1998;Li et al 2002), or act as settlement cues for invertebrate larvae to initiate the transformation into a sessile, juvenile form (Morse et al 1988;Heyward and Negri 1999;Negri et al 2001;Kitamura et al 2009;Tebben et al 2011Tebben et al , 2015Sneed et al 2014). For example, different classes of macroalgae defend themselves chemically against herbivores and produce SMs with antimicrobial and antifouling activity (Schupp and Paul 1994;Paul et al 2014;Schwartz et al 2016).…”

“…Although the ecological role of sponge crude extracts has been evaluated for numerous sponge species, assignment of activities to specific NPs is lacking behind. Investigated bioactivities included antipredatory, antifouling, antimicrobial, and allelopathic functions (Rohde et al 2015;Helber et al 2017Helber et al , 2018. Several studies are providing evidence that sponges are chemically defended from predation and pathogens by compounds that either the host or other associated microorganisms had produced (Pawlik 2011;Hentschel et al 2012).…”

“…Moreover, several natural products (NPs) have the ability to protect against nonbiological impacts, such as high light intensities or elevated temperatures, and to obtain reproduction advantages for their producers (Ludwig-Müller and Gutzeit 2014). In the marine environment, SMs fulfill manifold tasks for their producers as they, for instance, act as a chemical defense against predators (Rohde et al 2015;Helber et al 2017;Rohde and Schupp 2018) or have antimicrobial effects against pathogenic microbes (Goecke et al 2010;Rohde et al 2015;Helber et al 2018). Furthermore, MNPs are important for inducing larval settlement of benthic invertebrates (Yvin et al 1985;Morse et al 1988;Tebben et al 2011Tebben et al , 2015Harder et al 2018), thereby maintaining and controlling community functioning and population dynamics.…”