Characterization of polycyclic aromatic hydrocarbons in the Great Lakes Basin using dreissenid mussels.

The National Oceanic and Atmospheric Administration (NOAA), National Centers for Coastal Ocean Science (NCCOS) Mussel Watch Program (MWP), conducts basin-wide monitoring and place-based assessments using dreissenid mussels as bioindicators of chemical contamination in the Laurentian Great Lakes. Polycyclic aromatic hydrocarbons (PAHs) body burden results for the period 2009-2018 were combined into one dataset from multiple MWP studies allowing for a robust characterization of PAH contamination. Patterns in PAH data were identified using descriptive statistics and machine learning techniques. Relationships between total PAH concentration in dreissenid mussel tissue, impervious surface percentages, and PAH relative concentration were identified and used to build a predictive model for the Great Lakes Basin. Significant positive correlation was identified by the Spearman's rank correlation test between total PAH concentration and percent impervious surface. The findings support the paradigm that PAHs are primarily derived from land-based sources. Offshore and riverine locations had the lowest and highest median total PAH concentrations, respectively. PAH assemblages and ratios indicated that pyrogenic sources were more predominant than petrogenic sources and that PAHs at offshore sites exhibited relatively more weathering compared to inshore sites.

A typology for strategies to connect citizen science and management.

One of the often cited benefits of citizen science is better connecting citizens and their science to adaptive management outcomes. However, there is no consensus as to whether this is a reasonable expectation, and if so, how best to approach creating a successful link to management. This review finds cases where the citizen science-management link is explicitly discussed and places each case into a meta-analysis framework that will help define some general successful approaches to forming such a link. We categorize the types of linkages between citizen science and management along two main axes: cooperative to adversarial and deliberate to serendipitous. Cooperative and deliberate types of linkages are the most common, likely due to a mix of causes: that such links are the most commonly written about in the scientific literature, because such links tend to exist for longer amounts of time, and because other types of links tend to drift toward the cooperative/deliberate approach over time.

Process, not product: investigating recommendations for improving citizen science "success".

Citizen science programs are increasingly popular for a variety of reasons, from public education to new opportunities for data collection. The literature published in scientific journals resulting from these projects represents a particular perspective on the process. These articles often conclude with recommendations for increasing "success". This study compared these recommendations to those elicited during interviews with program coordinators for programs within the United States. From this comparison, success cannot be unilaterally defined and therefore recommendations vary by perspective on success. Program coordinators tended to have more locally-tailored recommendations specific to particular aspects of their program mission.

The geography of mercury and PCBs in North Carolina's local seafood.

Mercury and PCBs are used by non-governmental organizations and federal agencies to inform seafood safety recommendations. Pollution dynamics suggest recommendations on the national scale may be too large to be accurate. We tested softshell and hardshell blue crab, white and pink shrimp, oysters, clams, spot, and mullet from fishers in each of the three North Carolina fishery districts. We measured mercury using EPA method 7473 and PCBs using a commercially available ELISA kit. Over 97% of samples were below the Environmental Protection Agency levels of concern for both mercury and PCBs. Mercury and PCBs have different spatial dynamics, but both differ significantly by water body, suggesting that seafood safety recommendations should occur by water body instead of at the national scale. This finding supports previous research suggesting that differences in water chemistry, terrestrial influence, and flushing time in a particular water body control the contaminant load in locally resident species.

Phylogenetic ecology of leaf surface traits in the milkweeds (Asclepias spp.): chemistry, ecophysiology, and insect behavior.

The leaf surface is the contact point between plants and the environment and plays a crucial role in mediating biotic and abiotic interactions. Here, we took a phylogenetic approach to investigate the function, trade-offs, and evolution of leaf surface traits in the milkweeds (Asclepias). Across 47 species, we found trichome densities of up to 3000 trichomes cm(-2) and epicuticular wax crystals (glaucousness) on 10 species. Glaucous species had a characteristic wax composition dominated by very-long-chain aldehydes. The ancestor of the milkweeds was probably a glaucous species, from which there have been several independent origins of glabrous and pubescent types. Trichomes and wax crystals showed negatively correlated evolution, with both surface types showing an affinity for arid habitats. Pubescent and glaucous milkweeds had a higher maximum photosynthetic rate and lower stomatal density than glabrous species. Pubescent and glaucous leaf surfaces impeded settling behavior of monarch caterpillars and aphids compared with glabrous species, although surface types did not show consistent differentiation in secondary chemistry. We hypothesize that pubescence and glaucousness have evolved as alternative mechanisms with similar functions. The glaucous type, however, appears to be ancestral, lost repeatedly, and never regained; we propose that trichomes are a more evolutionarily titratable strategy.