Philosophiae Doctor - PhD / Coralline red algae (Corallinales, Hapalidiales, Sporolithales: Corallinophycidae, Rhodophyta) are widespread and common in all the world’s oceans (Adey & McIntyre 1973; Johansen 1981; Littler et al. 1985; Björk et al. 1995; Aguirre et al. 2007; Harvey & Woelkerling 2007; Littler & Littler 2013). They achieve their highest diversity in the tropics and subtropics (Björk et al. 1995; Littler & Littler 2013; Riosmena-Rodríguez et al. 2017), and within the photic zone of rocky shores (Lee 1967; Littler 1973; Adey 1978; Adey et al. 1982; Steneck 1986; Kendrick 1991; Kaehler & Williams 1996; Gattuso et al. 2006; van der Heijden & Kamenos 2015; Riosmena-Rodríguez et al. 2017) where they serve as important carbonate structures (Adey et al. 1982; Littler & Littler 1994, 1997; Vermeij et al. 2011) and habitats for a host of marine species (Foster 2001; Amado-Filho et al. 2010; Foster et al. 2013; Littler & Littler 2013; Riosmena-Rodríguez et al. 2017). Coralline algae are resilient, inhabiting extreme conditions that include: low temperatures (Adey 1970, 1973; Freiwald & Hendrich 1994; Barnes et al. 1996; Freiwald 1996; Aguirre et al. 2000; Roberts et al. 2002; Björk et al. 2005; Martone et al. 2010); limited light exposures (Adey 1970; Littler & Littler 1985; Littler et al. 1985; Liddell & Ohlhorst 1988; Dullo et al. 1990; Littler & Littler 1994; Iryu et al. 1995; Stellar and Foster 1995; Gattuso et al. 2006; Aguirre et al. 2007; Littler & Littler 2013); severe wave action (Steneck 1989; Littler & Littler 2013); intense grazing pressures (Steneck 1989; Steneck & Dethier 1994; Maneveldt & Keats 2008; Littler & Littler 2013), highly fluctuating salinities (Harlin et al. 1985; Barry & Woelkerling 1995; Barnes et al. 1996; Wilson et al. 2004); including occurring in freshwater (Žuljevic et al. 2016), and constant sand scouring (Littler & Littler 1984; D’Antonio 1986; Kendrick 1991; Chamberlain 1993; Dethier 1994).

<p>To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn / 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn / 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association...</p>

<p>To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn / 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn / 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association...</p>

Magister Scientiae (Biodiversity and Conservation Biology) / To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn; 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn; 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association. / South Africa