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Sub-monthly prediction of harmful algal blooms based on automated cell imaging
Get PDFHarmful algal blooms (HABs) are an increasing threat to global fisheries and human health. The mitigation of HABs requires management strategies to successfully forecast the abundance and distribution of harmful algal taxa. In this study, we attempt to characterize the dynamics of 2 phytoplankton genera (Pseudo-nitzschia spp. and Dinophysis spp.) in Narragansett Bay, Rhode Island, using empirical dynamic modeling. We utilize a high-resolution Imaging FlowCytobot dataset to generate a daily-resolution time series of phytoplankton images and then characterize the sub-monthly (1–30 days) timescales of univariate and multivariate prediction skill for each taxon. Our results suggest that univariate predictability is low overall, different for each taxon and does not significantly vary over sub-monthly timescales. For all univariate predictions, models can rely on the inherent autocorrelation within each time series. When we incorporated multivariate data based on quantifiable image features, we found that predictability increased for both taxa and that this increase was apparent on timescales \u3e7 days. Pseudo-nitzschia spp. has distinctive predictive dynamics that occur on timescales of around 16 and 25 days. Similarly, Dinophysis spp. is most predictable on timescales of 25 days. The timescales of prediction for Pseudo-nitzschia spp. and Dinophysis spp. could be tied to environmental drivers such as tidal cycles, water temperature, wind speed, community biomass, salinity, and pH in Narragansett Bay. For most drivers, there were consistent effects between the environmental variables and the phytoplankton taxon. Our analysis displays the potential of utilizing data from automated cell imagers to forecast and monitor harmful algal blooms
Passive-Sampler-Derived PCB and OCP Concentrations in the Waters of the World─First Results from the AQUA-GAPS/MONET Network
Get PDFPersistent organic pollutants (POPs) are recognized as pollutants of global concern, but so far, information on the trends of legacy POPs in the waters of the world has been missing due to logistical, analytical, and financial reasons. Passive samplers have emerged as an attractive alternative to active water sampling methods as they accumulate POPs, represent time-weighted average concentrations, and can easily be shipped and deployed. As part of the AQUA-GAPS/MONET, passive samplers were deployed at 40 globally distributed sites between 2016 and 2020, for a total of 21 freshwater and 40 marine deployments. Results from silicone passive samplers showed α-hexachlorocyclohexane (HCH) and γ-HCH displaying the greatest concentrations in the northern latitudes/Arctic Ocean, in stark contrast to the more persistent penta (PeCB)- and hexachlorobenzene (HCB), which approached equilibrium across sampling sites. Geospatial patterns of polychlorinated biphenyl (PCB) aqueous concentrations closely matched original estimates of production and use, implying limited global transport. Positive correlations between log-transformed concentrations of Σ7PCB, ΣDDTs, Σendosulfan, and Σchlordane, but not ΣHCH, and the log of population density (p \u3c 0.05) within 5 and 10 km of the sampling sites also supported limited transport from used sites. These results help to understand the extent of global distribution, and eventually time-trends, of organic pollutants in aquatic systems, such as across freshwaters and oceans. Future deployments will aim to establish time-trends at selected sites while adding to the geographical coverage
IPBES Invasive Alien Species Assessment: Summary for Policymakers
Get PDFSummary for Policymakers of the Thematic Assessment Report on Invasive Alien Species and their Control of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services
Saturating growth rate against phosphorus concentration explained by macromolecular allocation
No full textThe saturating relationship between phytoplankton growth rate and environmental nutrient concentration has been widely observed, yet the mechanisms behind the relationship remain elusive. Here, we use a mechanistic model of phytoplankton and show that the saturating relationship between growth rate and phosphorous concentration can be interpreted by intracellular macromolecular allocation. At low nutrient levels, the diffusive nutrient transport linearly increases with the phosphorous concentration, while the internal phosphorous requirement increases with the growth rate, leading to a non-linear increase in the growth rate with phosphorous. This increased phosphorous requirement is due to the increased allocation to biosynthetic and photosynthetic molecules. The allocation to these molecules reaches a maximum at high-phosphorous concentration, and the growth rate no longer increases despite the rise in phosphorous concentration. The produced growth rate and phosphorous relationships are consistent with the data of phytoplankton across taxa. Our study suggests that the key control of phytoplankton growth is internal, and nutrient uptake is only a single step in the overall process
Translation, Weather, and Erasure in Bhanu Kapil’s Schizophrene
Get PDFFor Bhanu Kapil, the drafting process of writing involves the translation of non-linguistic realities into storytelling, the nature of which must leave room for the performative experience that shapes writing. In Schizophrene (2011), Kapil engaged in adventitious composition processes when she sealed her manuscript in a Ziploc bag and threw it in the garden to spend months outdoors in the Colorado winter. The text, full of gaps created by the erased parts of the “winterized” manuscript, documents schizophrenia in diasporic Indian and Pakistani communities. The decaying process of the book that created a void in her writing also impacts the narrative’s own exploration of white space, gaps, syntactic experimentation, and fragmentation. These elements attempt to translate the experience of Kapil’s family and the effect of colonization on immigrants. The initial “failed” document attests to the impossibility of telling the story of women’s inter-generational trauma inherited from postcolonial and patriarchal violence. Translating these elements into a new form of narration relies on the refusal to reproduce old narrative patterns inherited from Western and patriarchal modes of writing. Instead, resisting traditional plot structures, Kapil pays close attention to repetition and association: they echo, verbally, the “light touch,” which “regular and impersonally repeated” is healing, “for non-white subjects (schizophrenics) as anti-psychotic medication” (71). Consequently, this mode of writing proposes yet another level of translation, one that focuses on the information that comes from bodies and its transfer into the physical form of texts. While Schizophrene is not literally a translation, it involves a multi-layered engagement of what can be translated from the trauma of the multigenerational oppression of women