ENERGY CONTENT AND CHEMICAL DEFENSE OF THE ARTICULATE BRACHIOPOD LIOTHYRELLA-UVA (JACKSON, 1912) FROM THE ANTARCTIC PENINSULA

Energy levels (xBAR + 1 SD) of whole soft body tissues and shells of t he antarctic brachiopod Liothyrella uva (Jackson, 1912) were 9.0 +/- 1 .0 and 1.1 +/- 0.4 . kJ . g-1 dry wt, respectively. The majority of th e energy in the soft body tissues was attributable to NaOH-soluble pro tein (17.4% dry wt) and in the shell to lipid (2.6% dry wt). An intact individual with a shell length of 3.4 cm and a wet and dry wt of 5.8 and 2.9 g, respectively, contained a total of 9.6 kJ. As dense populat ions of L. uva occur in the Southern Ocean, this species represents a considerable potential energy resource for predators, including sea st ars and fish (ca 10(3) kJ . m-2 in some areas). Total crude extracts o f whole brachiopod soft tissues caused significant retraction of senso ry tube-feet in 6 species of sympatric sea stars. Control assays emplo ying whole crude extracts of the fresh soft tissues of the antarctic l impet Nacella concinna (Strebel, 1908) or seawater alone did not elici t significant sustained tube-foot retraction. Bioactivity was diminish ed in frozen extracts of brachiopod soft tissues exposed to the sensor y tube-feet of the sea star Odontaster validus (Koehler, 1906), but wa s not diminished in the tube-foot retraction response of the sea star Neosmilaster georgianus (Studer, 1885). Lyophilized brachiopod soft ti ssues ground into a fine powder and embedded at a concentration of 2% (wt:vol) in agar pellets containing 5% krill caused significant feedin g deterrence in an allopatric fish (the sheepshead minnow Cyprinidon v ariegatus Lacepede 1803). These findings suggest that, similar to temp erate zone and tropical brachiopods, body tissues of this antarctic br achiopod are unpalatable to potential predators.