Late Larval Development and Onset of Symbiosis in the Scleractinian Coral Fungia scutaria

Abstract

Many corals that harbor symbiotic algae (zooxanthellae) produce offspring that initially lack zooxanthellae. This study examined late larval development and the acquisition of zooxanthellae in the scleractinian coral Fungia scutaria, which produces planula larvae that lack zooxanthellae. Larvae reared under laboratory conditions developed the ability to feed 3 days after fertilization; feeding behavior was stimulated by homogenized Artemia. Larvae began to settle and metamorphose 5 days after fertilization. In laboratory experiments, larvae acquired experimentally added zooxanthellae by ingesting them while feeding. Zooxanthellae entered the gastric cavity and were phagocytosed by endodermal cells. As early as 1 h after feeding, zooxanthellae were observed in both endodermal and ectodermal cells. Larvae were able to form an association with three genetically distinct strains of zooxanthellae. Both zooxanthellate and azooxanthellate larvae underwent metamorphosis, and azooxanthellate polyps were able to acquire zooxanthellae from the environment. Preliminary evidence suggests that the onset of symbiosis may influence larval development; in one study symbiotic larvae settled earlier than aposymbiotic larvae. Protein profiles of eggs and larvae throughout development revealed a putative yolk protein doublet that was abundant in eggs and 1-day-old larvae and was absent by day 6. This study is the first to examine the onset of symbiosis between a motile cnidarian host and its algal symbiont.

Potential bleaching effects on coral reproduction

“…The surviving F. scutaria larvae were cleaned and divided into small bowls of either 100 or 50 mL FSW to yield 1000-2500 larvae mL À1 . Then, 300 mL brine shrimp essence (frozen brine shrimp were crushed into FSW; the brine shrimp were then filtered out and only the supernatant used) was added to each small bowl of larvae 5 min before the addition of Symbiodinium to initiate a searching and feeding response from the larvae (Schwarz et al 1999). Symbiodinium were extracted and cleaned as described previously (Schwarz et al 1999;Hagedorn et al 2010) and concentrated to a density of 1 Â 10 7 mL À1 before being added to the small bowls of larvae to result in a final concentration of 1 Â 10 6 mL À1 Symbiodinium in each bowl.…”

“…The F. scutaria larvae from the two bowls (described above) that produced effective infections were used in settlement experiments on Day 6, as described previously (Schwarz et al 1999). Briefly, infected larvae (n ¼ ,100 per well) were placed in 12-well plastic plates (n ¼ 4 per bowl) that had a 2-to 3-day biofilm.…”

“…Therefore, we were interested in detailing the reproductive profile of Fungia scutaria and Montipora capitata coral populations in Kaneohe Bay (most of which bleached in October 2014), 9 months after their recovery. We compared the details of their post-bleaching reproductive profile to the more than 30 years of reproductive data on F. scutaria in Kaneohe Bay (Krupp 1983;Schwarz et al 1999;Hagedorn et al 2006Hagedorn et al , 2010Hagedorn et al , 2012Hagedorn et al , 2015a) and the almost 20 years of data for M. capitata reproduction (Field 1998;Cox 2007;Padilla-Gamiño et al 2011, 2014PadillaGamiño and Gates 2012;Hagedorn et al 2015b). Nevertheless, without consistent yearly reproductive profiles assessed in a similar manner, these historical comparisons can only be suggestive at best.…”

Molecular signatures of host specificity linked to habitat specialization in Exaiptasia sea anemones

“…One possibility is that early uptake of different Symbiodinium types could influence the type of substrate upon which anemone larvae prefer to settle. Larval settlement of Fungia scutaria , a scleractinian coral that also acquires symbionts horizontally, occurred earlier when larvae were colonized by Symbiodinium (Schwarz, Krupp, & Weis, 1999) . Exaiptasia larvae similarly take up Symbiodinium prior to settlement and metamorphosis (Wolfowicz et al., 2016).…”

A New Host and Range Record for the Gall CrabFungicola fageias a Symbiont of the Mushroom CoralLobactis scutariain Hawai‘i

“…It is the largest and most common mushroom coral in the Hawaiian archipelago, where it was traditionally known as Fungia scutaria (Edmondson 1946, Maragos 1977, Hoover 1999, Fenner 2005. This species has been used in coral reef research in Käne'ohe Bay and Waikïkï Reef (O'ahu Island) or in laboratory experiments with specimens taken from those localities, which has resulted in numerous publications on its ecology and physiology over a long period of time (e.g., Edmondson 1929, Stephens 1962, Bosch 1967, Yamazato 1970, Pearse 1971, Jokiel and Cowdin 1976, Krupp 1982, 1983, 1984, 1985, Chadwick 1988, Romano 1988, Krupp et al 1993, Jokiel and Bigger 1994, Schwarz et al 1999, Weis et al 2001, Hagedorn et al 2006, Concepcion et al 2010, Schnitzler et al 2012. Additional references can be found in the work by Coles et al (2002).…”