*2.2. Gnathiid Collection*

For the GBR study, gnathiids were obtained from a culture maintained at LIRS since 2001, which uses the continual availability of wrasse *Hemigymnus melapterus* (Labridae) as hosts [102]. The culture is outdoors and uses a flow-through seawater system that obtains water directly from the nearby reefs. The previous exposures of the experimental (and previous generations) of gnathiids would have, therefore, reflected similar temperatures to the ocean and land ones [102].

Gnathiids for the Philippines study were collected from the shallow fringing coral reefs (<10 m) of Cangmating reef (9◦21 18.38" N, 123◦17 58.91" E) and Agan-an reef (9◦20 2.6" N, 123◦18 41.5" E) in Sibulan and from Bantayan reef (9◦19 49.22" N, 123◦18 43.43" E) in Dumaguete City, all within Negros Oriental Province. The Bantayan reef has small patch reefs with inshore seagrass beds. Cangmating and Agan-an have larger patch reefs and inshore seagrass beds. Gnathiids are common at all three sites [103,104]. Gnathiids were collected using light traps, adapted from Artim et al. (2015) [89] and Artim and Sikkel (2016) [105]. The traps were set at dusk and retrieved the following morning and then transported by boat to the SU-IEMS laboratory where they were emptied into individual 10 L plastic buckets with aerators. The contents of each trap were filtered with a funnel and 55 μm plankton mesh. The gnathiids were then sorted using a stereoscope and placed in an aquarium (27 L) with fresh, filtered, aerated seawater. The species of gnathiids collected were unknown due to difficulty with species identification of the juvenile stages [73], and the fact that no species have yet been formally described from our Philippines study region.
