Over 20 species of asteroids were devastated by a sea star wasting disease (SSWD) epizootic, linked to a densovirus, from Mexico to Alaska in 2013 and 2014. For Pisaster ochraceus from the San Juan Islands, South Puget Sound and Washington outer coast, time-series monitoring showed rapid disease spread, high mortality rates in 2014, and continuing levels of wasting in the survivors in 2015. Peak prevalence of disease at 16 sites ranged to 100%, with an overall mean of 61%. Analysis of longitudinal data showed disease risk was correlated with both size and temperature and resulted in shifts in population size structure; adult populations fell to one quarter of pre-outbreak abundances. In laboratory experiments, time between development of disease signs and death was influenced by temperature in adults but not juveniles and adult mortality was 18% higher in the 19°C treatment compared to the lower temperature treatments. While larger ochre stars developed disease signs sooner than juveniles, diseased juveniles died more quickly than diseased adults. Unusual 2–3°C warm temperature anomalies were coincident with the summer 2014 mortalities. We suggest these warm waters could have increased the disease progression and mortality rates of SSWD in Washington State.

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Anemonefishes (genera: Amphiprion and Premnas; family Pomacentridae) are a group of 28 species of coral reef fishes that are found in obligate symbiosis with large tropical sea anemones. A phylogenetic hypothesis based on morphological analyses of this group suggests that the ancestral anemonefish was a generalist with similar morphology to other pomacentrids, and that it gave rise to other anemonefish species that were more specialized for living with particular species of host anemones. To test this hypothesis we constructed a molecular phylogeny for the anemonefishes by sequencing 1140 base pairs of the cytochrome b gene and 522 base pairs of the 16S rRNA gene for six species of anemonefishes (representatives of all subgenera and species complexes) and two other pomacentrid species. Three methods of phylogenetic analysis all strongly supported the conclusion that anemonefishes are a monophyletic group. The molecular phylogeny differs from the tree based on morphological data in that the two species of specialized anemonefishes (Premnas biaculeatus and Amphiprion ocellaris) were assigned to a basal position within the clade, and the extreme host generalist (Amphiprion clarkii) to a more derived position. Thus, the initial anemonefish ancestors were probably host specialists and subsequent speciation events led to a combination of generalist and specialist groups. Further phylogenetic studies of additional anemonefish species are required to substantiate this hypothesis.

We found high population densities of Hydra canadensis (up to 30,000 m ') on macrophytes in Lake Opinicon (Ontario, Canada) and tested whether they influenced the survival of larval bluegill, Lepomis macrochirus. Hydra were observed to capture and ingest bluegill larvae in laboratory trials, IndiAduals that ingested fish larvae turned black; those fed a variety of crustacean species remained brown. The ingestion rate of Hydra on larvae in 8-liter laboratory microcosms was higher during the night (0.197 larvae predator-l h-l) than during the day (0.111 larvae predator-l h-l), Many larvae also died after escaping from the stinging tentacles of Hydra (on average 26% of larval mortality). Population densities of Hydra were highest on the macrophyte Myriophyllum spicatum. Bluegill colonies were surrounded by dense beds of M. spicatum in some areas, and larvae in the colonies had to swim through the plants (with the attached Hydra) in order to reach open water. We sampled Hydra in the vicinity of bluegill colonies on the morning after larval swim-up. The number of black Hydra decreased with increasing distance from a colony; 72% black within colonies, 45% at 0.5 m outside colonies, and 31% at 2 m outside of colonies. We estimate that up to 20% of the larvae produced by a colony csn be killed by Hydra within this 2-m zone. Many more larvae likely die as a result of encounters with Hydra that are abundant throughout the lake.