Predicting the impacts of ocean acidification in coastal habitats is complicated by bio-physical feedbacks between organisms and carbonate chemistry. Daily changes in pH and other carbonate ...parameters in coastal ecosystems, associated with processes such as photosynthesis and respiration, often greatly exceed global mean predicted changes over the next century. We assessed the strength of these feedbacks under projected elevated CO2 levels by conducting a field experiment in 10 macrophyte-dominated tide pools on the coast of California, USA. We evaluated changes in carbonate parameters over time and found that under ambient conditions, daytime changes in pH, pCO2, net ecosystem calcification (NEC), and O2 concentrations were strongly related to rates of net community production (NCP). CO2 was added to pools during daytime low tides, which should have reduced pH and enhanced pCO2. However, photosynthesis rapidly reduced pCO2 and increased pH, so effects of CO2 addition were not apparent unless we accounted for seaweed and surfgrass abundances. In the absence of macrophytes, CO2 addition caused pH to decline by ∼0.6 units and pCO2 to increase by ∼487 µatm over 6 hr during the daytime low tide. As macrophyte abundances increased, the impacts of CO2 addition declined because more CO2 was absorbed due to photosynthesis. Effects of CO2addition were, therefore, modified by feedbacks between NCP, pH, pCO2, and NEC. Our results underscore the potential importance of coastal macrophytes in ameliorating impacts of ocean acidification.
As human modifications of the earth’s systems have increased, so has interest in understanding past changes in order to predict future ecological trajectories. We compared historical (1969–1971) and ...contemporary (2005–2009) abundances of species in the marine epibenthic community of Bodega Harbor, California, USA. Between these 2 time periods, we found a decrease in the abundance of native species and an increase in non-native dominance, including of several species that were either rare or absent ~35 yr ago and whose introduction was likely human-mediated. This compositional shift was concurrent with an increase in local water temperature of ~1°C over the same interval. To address the potential role of ocean warming in facilitating the increase of the new dominant species and maintaining compositional shifts, we evaluated the correlation between temperature and recruitment for 15 species. We found that recruitment timing and magnitude were positively related to temperature for non-native species but not for native species overall. Combined with previous results suggesting effects of ocean warming on the relative performance of native vs. non-native species in this community, our study indicates the potential for continued dominance of non-native species in Bodega Harbor due to local temperature increases. Simultaneously, anthropogenic transport has been responsible for several recent introductions of competitively dominant species, and shifts in contaminant loads or other factors between the 2 time periods could also contribute to compositional shifts, both historically and in the future. Our results highlight the need for studies of these additional factors, as well as the mechanisms underlying their effects on compositional shifts, in order to predict future changes.
Susan Lynn Williams (1951–2018) was an exceptional marine ecologist whose research focused broadly on the ecology of benthic nearshore environments dominated by seagrasses, seaweeds, and coral reefs. ...She took an empirical approach founded in techniques of physiological ecology. Susan was committed to applying her research results to ocean management through outreach to decision-makers and resource managers. Susan’s career included research throughout the USA in tropical, temperate, and polar regions, but she specialized in tropical marine ecology. Susan’s scholarship, leadership, and friendship touched many people, leading to this multi-authored paper. Susan’s scholarship was multi-faceted, and she excelled in scientific discovery, integration of scientific results, application of science for conservation, and teaching, especially as a mentor to undergraduate and graduate students and postdoctoral scholars. Susan served in a variety of leadership positions throughout her career. She embodied all facets of leadership; leading by example, listening to others, committing to the “long haul,” maintaining trust, and creating a platform for all to shine. Susan was an important role model for women in science. Susan was also a loyal friend, maintaining friendships for many decades. Susan loved cooking and entertaining with friends. This paper provides an overview of the accomplishments of Susan in the broad categories of scholarship, leadership, and friendship.
We investigated physiological traits responsible for determining the tide-height and latitudinal distributions of Northeastern Pacific Nucella congeners. First, we determined the thermotolerances of ...two species of intertidal dogwhelks, N. ostrina and N. canaliculata, which co-occur on the Oregon coast. We found that N. ostrina, which are distributed higher on the shore, and thus experience higher habitat temperatures, than N. canaliculata, had correspondingly higher heat-coma temperatures. Second, we acclimated individuals of all five Northeastern Pacific Nucella congeners to a common temperature and determined their thermotolerances, measured as recovery from thermal exposure, after a 5-day, 3-week, and 7-week acclimation period. The south-latitude (N. emarginata) and mid-latitude (N. ostrina) high-intertidal species were more thermotolerant than the mid-latitude low-intertidal (N. canaliculata and N. lamellosa) and north-latitude high-intertidal (N. lima) species. The results of these two experiments suggest that temperature plays a role in determining the tide-height and latitudinal distributions of these Nucella species. Finally, we measured total and inducible levels of an evolutionarily conserved and ecologically relevant protein, the 70-kDa heat-shock protein (Hsp70), which has been found to confer thermotolerance in model laboratory organisms. The results showed that the level of total, not stress inducible, Hsp70 was a better predictor of thermotolerance and that there were species-specific differences in the relationship between Hsp70 expression and thermotolerance. We suggest that Hsp70 expression may be important in conferring thermotolerance in Nucella species in nature and that higher levels of molecular chaperones may underlie increased thermotolerance between conspecifics. PUBLICATION ABSTRACT
Filter-feeding invertebrates consume phytoplankton and detritus and therefore serve as important mediators of the exchange of materials from nearshore pelagic to intertidal benthic ecosystems. Here, ...we evaluated the linkages between nearshore and intertidal systems on temperate rocky reefs on the coasts of Oregon, USA, and New Zealand’s South Island. We used differences in the concentrations of both nearshore particulate organic carbon and chlorophylla(chla), a proxy for phytoplankton availability, at different sites in Oregon and New Zealand to evaluate the influences of suspended particulate organic material (POM) quality and quantity on the rates of carbon inputs associated with intertidal mussels (Mytilus californianusin Oregon andMytilus galloprovincialisin New Zealand). We also analyzed the carbon stable isotope ratios (δ13C) of intertidal mussels and nearshore POM to examine changes in mussel growth in carbon relative to changes in their potential food sources along gradients of POM quality (i.e. carbon-to-chlorophyll ratios, C:chla). In both Oregon and New Zealand, the δ13C in mussel tissues did not change along a gradient of food quality, whereas the δ13C of the POM declined as food quality declined (i.e. C:chlaincreased), suggesting that mussels were selectively consuming high-quality food. We also found that the availability of phytoplankton, a high-quality component of the POM, was a better predictor of mussel growth in carbon (mg C g−1d−1) than the total concentration of particulate organic carbon, which includes both higher-quality phytoplankton and lower-quality detrital material. Our results highlight the necessity of considering POM quality while evaluating the role of filter-feeders as mediators of carbon inputs into intertidal systems.
High-latitude marine ecosystems have experienced fewer species invasions than temperate marine ecosystems, a discrepancy that may be attributed to barriers such as low propagule pressure, extreme and ...seasonal abiotic conditions, and biotic resistance of relatively intact communities. Each of these barriers is being affected by climate change and increasing human activity in high-latitude (>55º N) areas. We reviewed the evidence for each of these barriers limiting species invasion in high-latitude areas in the northern hemisphere. Based on records from government documents of high‐latitude countries, non-native species appear to be increasing in number (in Denmark and the United States) although there remains a paucity of data on invasive species establishment for high-latitude regions. Future study is needed to identify the drivers and impacts of invasions at high latitudes so that managers looking to prevent invasions can focus their efforts on bolstering barriers to invasion in these unique ecosystems.
As climate change and invasive species, both individually and in concert, continue to elicit responses in native communities, we are challenged with finding strategies for predicting the strength of ...such impacts. The effects of invasive species are often determined by their abundance, and warming temperatures can alter species' demographic rates and, thus, population growth rates. Here, we combined lab experiments, field experiments and observations, and population modeling to predict the population dynamics of three marine invaders in response to climate warming. We projected population growth rate at an ambient and an increased temperature predicted by climate-change scenarios (+4°C) for three invasive species in the epibenthic fouling community of Bodega Harbor, California, USA: the tunicates Botrylloides violaceus and Botryllus schlosseri and the bryozoan Watersipora subtorquata. There was a positive effect of temperature on population growth rate for B. schlosseri, and further analysis revealed that this predicted increase was driven by warming effects on settler growth rate and adult fecundity. Increases indicated for non-native marine fouling species are especially pertinent when considering the potential cascading effects on community composition and functioning that can result from species invasions. Our results highlight the potential for marked increases in an invasive species in response to climate change, as well as the promising role that population modeling can play in elucidating the mechanisms of such responses.
► Population demographic modeling can be used to predict responses to climate change. ► We predicted impacts of ocean warming on three invasive marine species. ► Models were parameterized using lab and field experiments and observations. ► Warming is predicted to increase population growth rate for one invasive species. ► Increased population growth was driven by changes in fecundity and growth rates.
Biodiversity redistribution under climate change Pecl, Gretta T.; Araújo, Miguel B.; Bell, Johann D. ...
Science (American Association for the Advancement of Science),
03/2017, Letnik:
355, Številka:
6332
Journal Article
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Distributions of Earth's species are changing at accelerating rates, increasingly driven by human-mediated climate change. Such changes are already altering the composition of ecological communities, ...but beyond conservation of natural systems, how and why does this matter? We review evidence that climate-driven species redistribution at regional to global scales affects ecosystem functioning, human well-being, and the dynamics of climate change itself. Production of natural resources required for food security, patterns of disease transmission, and processes of carbon sequestration are all altered by changes in species distribution. Consideration of these effects of biodiversity redistribution is critical yet lacking in most mitigation and adaptation strategies, including the United Nation's Sustainable Development Goals.
Changes in latitudes, changes in aptitudes Sorte, Cascade J. B.; Hofmann, Gretchen E.
Marine ecology. Progress series (Halstenbek),
06/2004, Letnik:
274
Journal Article
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A paradigm in biogeography is that organisms have ‘abundant center’ distributions, with abundances peaking at the range center and declining towards the range boundaries. One explanation for this ...pattern is that abundances are associated with organisms’ physiological stress levels and performances, with organisms experiencing more stress at the range edges. Here we explored whether the intertidal dogwhelkNucella canaliculatawas distributed in an ‘abundant center’ pattern. We addressed the role of stress in setting the species’ range limits. We determined dogwhelk abundances at range-center and range-edge sites and measured physiological stress levels by quantifying the 70 kDa heat-shock protein as a biochemical stress index.N. canaliculatawas less abundant and more stressed at its southern range edge than at the range center, suggesting that populations at the range edge may be most impacted by global climate change.
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