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Marine invertebrates with skeletons made of high-magnesium calcite may be especially susceptible to ocean acidification (OA) due to the elevated solubility of this form of calcium carbonate. However, skeletal composition can vary plastically within some species, and it is largely unknown how concurrent changes in multiple oceanographic parameters will interact to affect skeletal mineralogy, growth and vulnerability to future OA. We explored these interactive effects by culturing genetic clones of the bryozoan Jellyella tuberculata (formerly Membranipora tuberculata) under factorial combinations of dissolved carbon dioxide (CO2), temperature and food concentrations. High CO2 and cold temperature induced degeneration of zooids in colonies. However, colonies still maintained high growth efficiencies under these adverse conditions, indicating a compensatory trade-off whereby colonies degenerate more zooids under stress, redirecting energy to the growth and maintenance of new zooids. Low-food concentration and elevated temperatures also had interactive effects on skeletal mineralogy, resulting in skeletal calcite with higher concentrations of magnesium, which readily dissolved under high CO2. For taxa that weakly regulate skeletal magnesium concentration, skeletal dissolution may be a more widespread phenomenon than is currently documented and is a growing concern as oceans continue to warm and acidify.

The little-known bryozoan Membranipora eburnea Hincks is redescribed and designated the type species of the new genus Jellyella. The twinned ancestrula of this malacostegan-grade cheilostome places it within the Membraniporidae, along with Membranipora and Biflustra. Jellyella is distinguished by the presence of intricately branched processes (spinules) projecting into the zooidal chambers, and a calcitic skeletal ultrastructure of transversely arranged, elongate spindles. The \"Gulf weed bryozoan,\" Membranipora tuberculata (Bosc), is also assigned to the new genus as Jellyella tuberculata. Both species of Jellyella seem primarily to encrust floating substrates: based on available museum material. J. eburnea usually grows on drifting shells of dead individuals of the cephalopod Spirula but can also be found as an epizoan of the floating gastropod Janthina and on algae; J. tuberculata is normally an epiphyte of Sargassum. Collections of Spirula shells from beaches around the Indian, Pacific, and Atlantic Oceans are commonly encrusted by J. eburnea but very seldom by any other bryozoans. Jellyella is therefore interpreted as a rare example of a pseudoplanktonic genus among the typically benthic bryozoans.