Search

Microplastics have been documented across marine ecosystems and food webs globally. To solve this pollution crisis, identifying the debris material is key to understanding its origin, pathway, and ultimately its source. Visually based techniques, however, are not diagnostic. Raman spectroscopy is an increasingly preferred identification method for its accuracy and reduced likelihood of misinterpretation, though it can be inaccessible due to cost and availability of relevant labeled polymer spectra for comparison. Here, we provide an open access reference library of high-quality, broad-spectrum Raman spectra of major polymer categories often present in the marine environment. The library includes (a) pristine anthropogenic polymers newly sourced from manufacturers (n=40), (b) weathered anthropogenic polymers collected from used consumer, beachcast, agricultural, and fishery sources (n=22), and (c) biological polymers representing diverse marine taxa, trophic levels, and tissues (n=17). This database can help researchers in this rapidly expanding field to identify polymers and debris pathways and in turn, facilitate greater understanding of the global issue of marine plastic pollution.

for paper in press at Front. Mar. Sci.: Southern sea otters (Enhydra lutris nereis) are currently >80% depleted with respect to both abundance and range occupancy baselines, challenging the long-term persistence of the species and the ecosystem benefits their populations might provide. From 2001-2018, the Monterey Bay Aquarium rescued stranded sea otter pups and reared them in captivity through a surrogacy program using non-releasable adult females. We gave 11,396 days of captive care to 56 otters, reintroduced them into the wild, and observed them over 894 total field days after release. This study describes the post-release movements of the 42 successfully released otters, quantifying their dispersal patterns and modeling environmental, demographic, and animal care influences through a machine learning framework. This random forest model specifically considers predictor variable correlation, accounts for individual and joint variable impacts, and evaluates robustness through sensitivity analyses. Heavy tailed dispersal models best explained the (n=641) daily movements of surrogate-reared otters, and the random forest outputs ranked population demography, population growth, and El Niño most significantly. Occasionally aided by recaptures, the scale of dispersals consistently declined after release, indicating successfully released otters stabilized their movements within three weeks in the wild. Our results show dispersal is an important metric for measuring the success of sea otter releases and suggest environmental factors (including climate) at release sites may determine the success of reintroduction programs.

Article available at https://peerj.com/articles/4565/. Abstract: The use of limbs for foraging is documented in both marine and terrestrial tetrapods. These behaviors were once believed to be less likely in marine tetrapods due to the physical constraints of body plans adapted to locomotion in a fluid environment. Despite these obstacles, ten distinct types of limb-use while foraging have been previously reported in nine marine tetrapod families. Here, we expand the types of limb-use documented in marine turtles and put it in context with the diversity of marine tetrapods currently known to use limbs for foraging. Additionally, we suggest that such behaviors could have occurred in ancestral turtles, and thus, possibly extend the evolutionary timeline of limb-use behavior in marine tetrapods back 70 million years. Through direct observation in situ and crowd-sourcing, we document the range of behaviors across habitats and prey types, suggesting its widespread occurrence. We argue the presence of these behaviors among marine tetrapods may be limited by limb mobility and evolutionary history, rather than foraging ecology or social learning. These behaviors may also be remnant of ancestral forelimb-use that have been maintained due to a semi-aquatic life history.

This is the open-access public repository for https://advances.sciencemag.org/content/4/2/eaao3946. ABSTRACT: Pelagic ecosystems are dynamic ocean regions whose immense natural capital is impacted by climate change, pollution, and commercial fisheries. Trophic level based indicators may reveal food web status of these systems, but the utility of such metrics has been debated due to targeting bias and sparse data resolution. Here we analyze a unique, fishery-independent dataset of North Pacific seabird tissues to inform ecosystem trends over 13 decades. Trophic position exhibited a broad decline in 5 of 8 species sampled, and no species increased their position. Bayesian diet reconstruction indicates a long-term shift from high- to low-trophic-level prey. Given species diet preferences, this suggests a shift from fish to squids, a result consistent with catch and ecosystem models. Machine learning further reveals that trophic position has a complex set of drivers including climate, commercial fisheries, and ecomorphology. Our results show that multispecies seabird ensembles may integrate the complex changes in marine ecosystems.

This is the public repository for data, graphics, and reviews for https://www.nature.com/articles/s41598-019-44117-2. The Abstract is: Plastic waste has been documented in nearly all types of marine environments and has been found in species spanning all levels of marine food webs. Within these marine environments, deep pelagic waters encompass the largest ecosystems on Earth. We lack a comprehensive understanding of the concentrations, cycling, and fate of plastic waste in sub-surface waters, constraining our ability to implement effective, large-scale policy and conservation strategies. We used remotely operated vehicles and engineered purpose-built samplers to collect and examine the distribution of microplastics in the Monterey Bay pelagic ecosystem at water column depths ranging from 5 to 1000 m. Laser Raman spectroscopy was used to identify microplastic particles collected from throughout the deep pelagic water column, with the highest concentrations present at depths between 200 and 600 m. Examination of two abundant particle feeders in this ecosystem, pelagic red crabs (Pleuroncodes planipes) and giant larvaceans (Bathochordaeus stygius), showed that microplastic particles readily flow from the environment into coupled water column and seafloor food webs. Our findings suggest that one of the largest and currently under-appreciated reservoirs of marine microplastics may be contained within the water column and animal communities of the deep sea.

Parent article found at: https://iopscience.iop.org/article/10.1088/2515-7620/ab4921 ABSTRACT: Wildlife contaminant loads are often used to indicate ecosystem health, but their interpretation is complicated by the dynamics affecting the trophic transfer of toxins. Yet, coupled analyses of trophic position and contaminants may provide insights that help resolve the underlying signal of contaminants in ecosystems. Here, we analyze heavy metal concentrations and trophic positions for pelagic seabirds across time and space. We derive metal-specific trophic transfer coefficients from the literature and use them to interpret the changes in raw heavy metal concentrations in two settings: (i) for eight seabird species across a 125-year timeline in Hawaii, and (ii) for contemporary specimens of two tern species across three ocean basins. While previous studies report how trophic position varies in these two settings, here we investigate how trophic downgrading may affect the observed raw changes in contaminants. Using this approach, we find the highly-toxic metal elements (Hg, As, Pb) decline after 1980. However, several other metals (Cu, Mn, Mo, Cd, Fe) increase from 1990–2015. Though simultaneous biomagnification and trophic downgrading may obscure contaminant analyses across space and time, the trophic declines we observed (≤0.5 trophic level) are likely not sufficient to influence such comparisons. In addition, as extrapolating contaminant concentrations across broad ranges of trophic levels may be prone to large uncertainties, careful selection of the focal species for analysis is required. While high trophic level species, such as long-lived, fish-eating seabirds, are ideal for monitoring environmental contaminants across large spatial or time scales, lower trophic level species, like primary producers and consumers, may be more suitable for quantifying the concentrations of bio-available contaminants entering the marine ecosystem and the base of the marine food webs. Monitoring low and high trophic levels simultaneously may provide an integrated perspective that is needed to quantify the contaminants entering and bio-magnifying through marine ecosystems.

from Biology Letters manuscript: Progress in global shark conservation has been limited by constraints to understanding the species composition and geographic origins of the shark fin trade. Previous assessments that relied on earlier genetic techniques and official trade records focused on abundant pelagic species traded between Europe and Asia. Here we combine recent advances in DNA barcoding and species distribution modeling to identify the species and source the geographic origin of fins sold at market. Derived models of species environmental niches indicated that shark fishing effort was concentrated within Exclusive Economic Zones (EEZs), mostly in coastal Australia, Indonesia, the United States, Brazil, Mexico, and Japan. By coupling two distinct tools, barcoding and niche modeling, our results provide new insights for monitoring and enforcement. They suggest stronger local controls of coastal fishing may help regulate the unsustainable global trade in shark fins.

DNA-based species composition of a large U.S. shark fin collection

Online repository of data for: Becker SL, Brainard RE, Van Houtan KS (2019) Densities and drivers of sea turtle populations across Pacific coral reef ecosystems. PLOS ONE 14(4): e0214972. https://doi.org/10.1371/journal.pone.0214972 ABSTRACT FOR PARENT ARTICLE: Sea turtle populations are often assessed at the regional to sub-basin scale from discrete indices of nesting abundance. While this may be practical and sometimes effective, widespread in-water surveys may enhance assessments by including additional demographics, locations, and revealing emerging population trends. Here, we describe sea turtle observations from 13 years of towed-diver surveys across 53 coral islands, atolls, and reefs in the Central, West, and South Pacific. These surveys covered more than 7,300 linear km, and observed more than 3,400 green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles. From these data, we estimated sea turtle densities, described trends across space and time, and modelled the influence of environmental and anthropogenic drivers. Both species were patchily distributed across spatial scales, and green turtles were 11 times more abundant than hawksbills. The Pacific Remote Island Areas had the highest densities of greens (3.62 turtles km-1, Jarvis Island), while American Samoa had the most hawksbills (0.12 turtles km-1, Ta’u Island). The Hawaiian Islands had the lowest turtle densities (island ave = 0.07 turtles km-1) yet the highest annual population growth (μ = 0.08, σ = 0.22), suggesting extensive management protections can yield positive conservation results. Densities peaked at 27.5°C SST, in areas of high productivity and low human impact, and were consistent with patterns of historic overexploitation. Though such intensive surveys have great value, they are logistically demanding and therefore have an uncertain budget and programmatic future. We hope the methods we described here may be applied to future comparatively low-cost surveys either with autonomous vehicles or with environmental DNA.

This is the code script repository for Gagne et al. 2020 is available at Github (https://github.com/MBayOtolith/DOI-10.17605-OSF.IO-JM7FN). This script is a parsed version of the full analysis. In the interest of storage space, all model feature development script is shown and the script is pre-run and model features are loaded as grid objects in the commented script. All data is available from the hosts described in the methods and via request. ABSTRACT: Understanding the distribution of life’s variety has driven naturalists and scientists for centuries, yet this has been constrained both by the available data and the models needed for their analysis. Here we compiled data for over 67,000 marine and terrestrial species and used artificial neural networks to model species richness with the state and variability of climate, productivity, and multiple other environmental variables. We find terrestrial diversity is better predicted by the available environmental drivers than is marine diversity, and that marine diversity can be predicted with a smaller set of variables. Ecological mechanisms such as geographic isolation and structural complexity appear to explain model residuals and also identify regions and processes that deserve further attention at the global scale. Improving estimates of the relationships between the patterns of global biodiversity, and the environmental mechanisms that support them, should help in efforts to mitigate the impacts of climate change and provide guidance for adapting to life in the Anthropocene.

Online repository of data and script for: https://www.frontiersin.org/articles/10.3389/fmars.2018.00317/full. Abstract: We analyze recently collected feather tissues from two species of seabirds, the sooty tern (Onychoprion fuscatus) and brown noddy (Anous stolidus), in three ocean regions (North Atlantic, North Pacific, and South Pacific) with different human impacts. The species are similar morphologically and in the trophic levels from which they feed within each location. In contrast, we detect reliable differences in trophic position amongst the regions. Trophic position appears to decline as the intensity of commercial fishing increases, and is at its lowest in the Caribbean. The spatial gradient in trophic position we document in these regions exceeds those detected over specimens from the last 130 years in the Hawaiian Islands. Modeling suggests that climate velocity and human impacts on fish populations strongly align with these differences.

Nearly three-fourths of U.S. citizens support strong environmental protection, yet the U.S. Congress has passed little momentous environmental legislation since 1980. This dearth of new bipartisan environmental policy has coincided with increasing political polarization, which has risen to historic levels in the United States. Though broadly supported by the U.S. public, environmental protection has wavered as the Trump administration has left the Paris Climate Agreement, lifted oil and gas regulations, and deprioritized endangered species conservation. This discordance between U.S. public opinion and policy action leads us to ask: How did environmental conservation become so polarized, and how can the U.S. environmental movement recover broad bipartisan support? As conservation scientists in academia, we believe our community has contributed to the partisan breakdown over the environment. We also believe that scientists have a critical role to play in bridging this divide. In this essay, we consider how “the environment” has become a political wedge issue in the United States and identify opportunities for conservation scientists to: (a) better respond to public needs and values; and (b) build support for bipartisan conservation policies through greater proximity with local communities, re-structured academic advancement policies, and 21st century approaches to training environmental science students.