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The California ribbed mussel, Mytilus californianus , is an ecosystem engineer crucial for the survival of many marine species inhabiting the intertidal zone of California. Here, we describe the first reference genome for M. californianus and compare it to previously published genomes from three other Mytilus species: M. edulis , M. coruscus , and M. galloprovincialis. The M. californianus reference genome is 1.65 Gb in length, with N50 sequence length of 118 Mb, and an estimated 86.0% complete single copy genes. Compared with the other three Mytilus species, the M. californianus genome assembly is the longest, has the highest N50 value, and the highest percentage complete single copy genes. This high-quality genome assembly provides a foundation for population genetic analyses that will give insight into future conservation work along the coast of California. [ABSTRACT FROM AUTHOR]

Intertidal mussels are well adapted to withstand emersion from water during low tide, but they may be intermittently exposed to waterborne toxicants such as copper, which targets physiological processes including metabolism, ammonia excretion, and osmoregulation. To determine if copper exposure damages intertidal organisms' ability to tolerate tidal emersion, Mediterranean mussels (Mytilus galloprovincialis) were exposed to copper for 96 h followed by 6 h of emersion. Oxygen uptake increased after copper exposure which suggests that copper accumulation caused moderate stress in the mussels, but ammonia excretion and anaerobic metabolism were unaffected by mixed copper and emersion exposures. Shell composition analyses indicate that cycles of copper exposure and tidal emersion may affect bivalve shell growth, but copper deposition into shells may decrease the metal's overall toxicity. Results suggest that copper does not damage M. galloprovincialis 's tolerance to tidal emersion, and insight is provided into the mussel's ability to overcome mixed stressor exposures. • Intertidal animals are exposed to multiple stressors throughout the tide cycle. • M. galloprovincialis is highly tolerant to tidal emersion and multiple stressors. • Copper toxicity and emersion did not have interactive effects on mussel physiology. • Cycles of copper exposure and emersion may alter bivalve shell growth. [ABSTRACT FROM AUTHOR]

Highlights: [•] Contaminants of emerging concern were measured in mussels along the California coast. [•] Sixty-eight total stations. Sixty-seven of the 167 analytes had at least one detect. [•] The influence of urbanization, agriculture, and ocean discharge was investigated. [•] Alkylphenols, lomefloxacin, and PBDE were the most abundant contaminants. [•] Perfluorinated compound and HBCD detection frequencies were greater than 25%. [Copyright &y& Elsevier]

The article discusses the study on non-native species' invasion to native predators on native and exotic prey species. It states that it is a worldwide epidemic which contributes to the communities' biotic globalization. It mentions that the Bodega Marine Reserve (BMR) in California becomes the study site of the conducted experiments. It notes that the study has incorporated bay mussels as materials for the experiment. It suggests that Mytilus galloprovincialis' limited establishment is contributed by predation as indicated by field and laboratory experiments.

Abstract: Sea otters in California are commonly infected with Toxoplasma gondii. A unique Type X strain is responsible for 72% of otter infections, but its prevalence in terrestrial animals and marine invertebrates inhabiting the same area was unknown. Between 2000 and 2005, 45 terrestrial carnivores (lions, bobcats, domestic cats and foxes) and 1396 invertebrates (mussels, clams and worms) were screened for T. gondii using PCR and DNA sequencing to determine the phylogeographic distribution of T. gondii archetypal I, II, III and Type X genotypes. Marine bivalves have been shown to concentrate T. gondii oocysts in the laboratory, but a comprehensive survey of wild invertebrates has not been reported. A California mussel from an estuary draining into Monterey Bay was confirmed positive for Type X T. gondii by multilocus PCR and DNA sequencing at the B1 and SAG1 loci. This mussel was collected from nearshore marine waters just after the first significant rainfall event in the fall of 2002. Of 45 carnivores tested at the B1, SAG1, and GRA6 typing loci, 15 had PCR-confirmed T. gondii infection; 11 possessed alleles consistent with infection by archetypal Type I, II or III strains and 4 possessed alleles consistent with Type X T. gondii infection. No non-canonical alleles were identified. The four T. gondii strains with Type X alleles were identified from two mountain lions, a bobcat and a fox residing in coastal watersheds adjacent to sea otter habitat near Monterey Bay and Estero Bay. Confirmation of Type X T. gondii in coastal-dwelling felids, canids, a marine bivalve and nearshore-dwelling sea otters supports the hypotheses that feline faecal contamination is flowing from land to sea through surface runoff, and that otters can be infected with T. gondii via consumption of filter-feeding marine invertebrates. [Copyright &y& Elsevier]

Abstract: The Point Conception, California, USA region (hereafter PC) is one of the most important biogeographic and oceanographic discontinuities on the US west coast. Here we address how mesoscale oceanographic and environmental variability in the region around PC, CA may influence the distribution, abundance and size of the mussel Mytilus californianus, a competitively dominant species in rocky intertidal assemblages along the northeast Pacific. Strong upwelling and high wave exposure dominate the California coast north of PC, and weak, seasonal upwelling and warmer water temperatures are characteristic of the region south/east of PC. We hypothesized that the gradient in temperature, upwelling, and wave exposure around PC would greatly influence patterns of recruitment and abundance of mussels, potentially underlying large-scale differences in community structure. We evaluated these predictions by surveying intertidal community structure, mussel distribution, size, abundance and recruitment at a range of intertidal sites around PC. We found that intertidal communities north of PC were dominated mainly by macrophytes, while mussels and barnacles were relatively scarce. Intertidal communities south of PC were dominated by mussels and barnacles, with a low abundance of macrophytes. Mussels were larger and mussel beds were more expansive and extended lower in elevation at sites ranging from north to south around PC. At northern sites, high abundances of sea star predators and elevated wave exposure effectively displaced the entire mussel zone upwards. We found no differences in the numbers of mussel recruits to sites around PC, suggesting that spatial patterns of mussel abundance were not driven by differential recruitment. These results suggest that unlike other well-studied systems, supply of benthic larvae does not underly the large-scale gradient in community structure around PC. We suggest that environmental conditions favorable to macroalgal growth north of PC, and conditions favorable to filter-feeder growth south of PC may underly mesoscale patterns of intertidal community structure in this region. [Copyright &y& Elsevier]

Abstract: The Point Conception, California, USA region (hereafter PC) is one of the most important biogeographic and oceanographic discontinuities on the US west coast. Here we address how mesoscale oceanographic variability in the region around PC affects the growth of the competitively dominant species in the rocky intertidal assemblage: the mussel Mytilus californianus. Strong upwelling and high wave exposure dominate the California coast north of PC, and weak, seasonal upwelling and warmer water temperatures are characteristic of the region south/east of PC. We hypothesized that the oceanographic gradients in temperature, upwelling, wave exposure and productivity around PC would exert strong bottom–up influences on growth rates of mussels, potentially underlying large-scale differences in community structure around the PC region. We evaluated these predictions by measuring mussel growth rates across the PC region both in the intertidal and offshore on moorings. Intertidal mussels grew at much higher rates at sites south relative to north of PC and growth rates decreased in a gradient from south to north. The gradient in intertidal mussel growth around PC was uncorrelated with inshore concentrations of chlorophyll-a, and was most strongly correlated with the alongshore gradient in wave exposure and intertidal temperature. Mussels on moorings offshore from the intertidal sites grew at much higher rates than those in the corresponding intertidal areas, and mussel growth rates did not differ significantly among moored locations around PC. The gradient of increasing temperature from north to south among mooring sites was correlated with a decreasing gradient in productivity in the same direction, potentially contributing to equal and opposite effects on mussel growth at offshore moorings. This study suggests that environmental factors such as cold temperatures and high wave exposure contribute to the spatial pattern of decreasing mussel growth rates from south to north around PC, underlying large-scale patterns of community structure in this region. [Copyright &y& Elsevier]

The California State Mussel Watch and the Regional Monitoring Program for Trace Substances have conducted biomonitoring for trace elements and organic contaminants in the San Francisco Estuary using transplanted bivalves (Mytilus californianus, Crassostrea gigas, and Corbicula fluminea). Significant declines (p<0.01) in contaminant concentrations in M. californianus for the period 1980-1996 were observed for PCBs, p,p'-DDE, cis-chlordane, dieldrin, and Ag, while a significant increase was observed for Cr (p<0.05). Certain limitations of the 'mussel watch' approach are illustrated by examining data on survival, body condition, and contaminant uptake, including the inability of the technique to predict accumulation of mercury and selenium at higher trophic levels in the ecosystem. These results indicate that biomonitoring using transplanted bivalves, when part of a consistently supported long-term program, can produce valuable data on the spatially and temporally averaged abundance and distribution of certain contaminants in coastal ecosystems. [ABSTRACT FROM AUTHOR]