An invasive whelk as predator and prey: The ecology of Kelletia kelletii in Monterey Bay, California

The recent expansion of Kellet's whelk Kelletia kelletii from south of Point Conception northwards to Monterey Bay, California introduced a novel feeding mode to the guild of invertebrate predators preying on trochid snails in central California. I used published literature and museum records, laboratory experiments, and field studies to determine the biogeography, feeding ecology, and trophic interactions of K. kelletii in central California, respectively.; I examined the available paleontological, archeological, and recent ecological evidence to determine the biogeography of Kelletia kelletii along the coast of California from the Plio-Pleistocene to the present. The data suggest the invasion of K. kelletii from southern California into central California during the mid-1900s is a recent phenomenon that either did not occur in the past or if it did, left no fossil evidence.; It has been suggested that invasive predators might have an advantage if they introduce a novel functional feeding mode to native prey. I used native and non-native sea stars and whelks as predators and allopatric Tegula spp. as prey in a series of laboratory feeding experiments to: (1) determine feeding preferences within predators; (2) compare consumption rates between different functional feeding modes; and (3) test for consumption rates differences between conspecifics from different regions. Preferences within predators were very consistent and similar between predator species: consumption was always highest for T. aureotincta and lowest for T. eiseni, and intermediate for T. brunnea, T. pulligo, and T. montereyi. The role of novelty as a species and a novel feeding mode contributed significantly to the whelk in one experiment. Pisaster giganteus prey selection indicated no local adaptation by the sea stars, and while the differences between whelks from southern and central California were not statistically significant, southern whelks never ate the well defended, less preferred T. eiseni.; Kelletia kelletii is also a novel prey resource for native predators. A five year study of permanent shell removal plots at the Hopkins Marine Life Refuge in Monterey Bay identified potential predators of the whelk and determined types and frequencies of shell damage. Most shell debris was categorized as either “window” damage (42%), whorls (25%), or spires (21%). Feeding trials with captive sea otters demonstrated that otters are capable of producing “window” damage and indicates they are important whelk predators in central California. Similar whelk shells in southern California are extremely rare and very old.