The ochre sea star, Pisaster ochraceus, experienced one of the highest mortality rates during this outbreak. P. ochraceus are distributed from Prince William Sound, Alaska, to Baja California, Mexico (Lamb et al. PROCEDURES The study had 2 phases. Retrieved May 10, 2010, from, Nybakken, J. The enrofloxacin concentration in those samples was determined by high-performance liquid chromatography. When the starfish were removed from the area as part of an experiment, the mussel population swelled and crowded out other species. The mussel needs to open its valves periodically to feed and breathe and the sea star can exert a powerful traction with its tube feet, pulling the two valves further open. ), Canada, can be a harsh environment; organisms are exposed to aerial and aquatic conditions on a daily and tidal basis.2 Varying vertical and horizontal gradients of physical factors have been found to play a role in determining the distribution of many intertidal species.3 Upper distributions of the shore that inter… Canada; 2Center for Population Biology, University of California, Davis, California 95616; and 3University of Washington, Department of Zoology, Seattle, Washington 98105 Abstract. Two untreated sea stars were housed with the treated animals following enrofloxacin administration during both phases. In 2013, a densovirus instigated a large sea star die-off that caused populations of Pisaster across the West Coast of North America to collapse. (Lahner); Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607.  There is no parental investment beyond spawning. In that time he has seen many changes is the near shore ecosystems creature make up. Studies have shown that when this organism is removed from communities, mussel populations (their natural prey) increase, which completely alters the species composition and reduces biodiversity.  In Pisaster the tube feet have suckers on their distal ends which allow them to attach to the rocky substrate and live in heavily wave-swept areas. A developmental response allows sea stars to stabilize a fast-growing mussel population. ANIMALS 28 sea stars of undetermined age and sex. Invertebrate Biology 128:4 381-390. Evasterias troscheli may be confused with P. ochraceus at times as well. (Phillips, Harms); Seattle Aquarium, 1483 Alaskan Way, Seattle, WA 98101. The ossicles are no higher than 2 mm. Pisaster ochraceus, Animal Diversity Web. , Members of Pisaster are dioecious but there is no sexual dimorphism and sexes can be separated only by the presence of eggs or sperm in the gonads. Kay, S.W.C., A.M. Gehman, and C.D.G. , P. ochraceus uses its tube feet to handle its prey. (Papich), Address correspondence to Dr. Rosenberg (, Alert me when new articles cite this article. In an experimental removal of P. ochraceus, it was shown that Mytilus californianus becomes almost completely dominant of the intertidal community. , Pisaster ochraceus has been described as a keystone species. Seattle: University of Washington Press.  With only a few natural predators (sea otters and seagulls) it is suggested that the principal enemies of P. ochraceus are human collectors and casual tidepool visitors. The wasting disease may be caused by a virus, but this is far from certain. With the sea stars gone, mussels took over the area and crowded out other species, including benthic algae that supported communities of … (Grzimeck, 1972) Known Predators. Identification. Twelve sea stars received an intracoelomic injection of enrofloxacin (5 mg/kg) or were immersed in an enrofloxacin solution (5 mg/L) for 6 hours during the injection and immersion phases, respectively. The aboral surface contains many small spines (ossicles) that are arranged in a netlike or pentagonal pattern on the central disk. , Many sea stars live to a minimal age of four years. ANIMALS 28 sea stars of undetermined age and sex..  During maturation of the gametes, the gonads increase in size and can account for up to 40 percent of the sea star's weight. P. ochraceus found within the warmer waters from Santa Barbara County to Baja California is the subspecies P. o. Marine Invertebrates of the Pacific Northwest. Immersion phase data were best fit with a 1-compartment model; elimination half-life, peak concentration, and area under the curve were 56 hours, 36.3 μg•h/mL, and 0.39 μg/mL, respectively. This normally causes decreased growth due to the increased acidity dissolving calcium carbonate. Fig.1). The ochre sea star (Pisaster ochraceus) is a keystone predator that can control the structure and maintain the diversity of rocky intertidal communities. Up to 90% of individuals showed signs of disease from June-August 2014. Mussels hold their valves together very securely but P. ochraceus can insert part of its everted stomach, or some digestive juices, through the narrow gap that exists where the byssal threads emerge from the shell. , At the larval stage, Pisaster ochraceus are filter feeders and their diet consists of plankton. In one bay, a toxic chemical is introduced that creates reproductive anomalies, wiping out the sea star population in a handful of years. In rocky intertidal habitats, populations of the dominant sea star Pisaster ochraceus were rapidly depleted, with magnitudes of decline in density among sites ranging from -2x to -9x (59 to 84%) and of biomass from -2.6x to -15.8x (60 to 90%) by September 2014. For each phase, noncompartmental analysis of naïve averaged pooled samples was used to obtain initial parameter estimates; then, population pharmacokinetic analysis was performed that accounted for the sparse sampling technique used. Scuba San Diego Inc,’s owner, Rod Watkins has 55 years diving on the California Coast line. Responses to low salinity by the sea star Pisaster ochraceus from high- and low-salinity populations. Feeds preferentially on mussels on northeast Pacific rocky shores. The many-rayed sunflower sea star (Pycnopodia helianthoides) of Alaska to California has 15 to 24 arms and is often 60 cm (24 inches) across. This heavy echinoderm can also be reddish or purple in color. Diversity of the invertebrates. PROCEDURES The study had 2 phases. Researchers found that when P. ochraceus was exposed to 21 °C (70 °F) and 770 ppm CO2 (beyond rises expected in the next century) that they survived. Retrieved May 10, 2010, from, "Pisaster ochraceus (Brandt, 1835)". Pisaster ochraceus has been described as a keystone species. When P. ochraceus is present there is a diverse intertidal community. However, because these mussels are a foundational species, they provide three-dimensional habitat for over 300 associated species inhabiting the mussel beds; thus, removing sea … Water vascular system fluid samples were collected from 4 sea stars and all controls at predetermined times during and after enrofloxacin administration.