Mesozooplankton omnivory in the upper San Francisco Estuary

While many studies have examined mesozooplankton feeding in coastal environments, less attention has been given to this subject in estuaries. We used bottle incubation experiments to measure the feeding rates of a cladoceran (Daphnia sp.), a calanoid copepod (Acartia spp.), and 2 cyclopoid copepods (Oithona davisae and Limnoithona tetraspina) on the protist plankton (<200 μm) of Suisun Bay, which is located in the upper San Francisco Estuary (SFE). Nanoplankton (2 to 15 μm) prey were highly abundant (2000 to 6000 cells ml-1 and 50 to 600 μg C l-1), whereas microplankton (15 to 200 μm) prey were 1 to 2 orders less abundant (10 to 90 cells ml -1 and 1 to 4 μg C l-1). There were few indications that mesozooplankton fed on nanoplankton, while microplankton were often significantly consumed. Daphnia sp. cleared all microplankton prey categories except diatoms at >2 ml predator (pred.)-1 h-1. O. davisae consumed only ciliates in September 2004, while in November 2004 it cleared both ciliates and diatoms at similar rates (0.8 ml pred.-1 h-1). L. tetraspina cleared only aloricate ciliates and flagellates (0.8 to 1.0 ml pred.-1 h-1). Acartia spp. had the highest clearance rates on diatoms of all the predators examined (mean <1.0 ml pred.-1 h-1) but cleared ciliates at even higher rates (>2.0 ml pred.-1 h-1). With respect to biomass ingestion, in every experiment mesozooplankton were found to ingest ciliate carbon at the highest rates (3 to 29 ng C pred.-1 h-1). Our results indicate that while estuarine mesozooplankton are often omnivorous, important species-specific differences exist, and microzooplankton, especially ciliates, are an important component of the upper SFE food web

A genetic reconstruction of the invasion of the calanoid copepod Pseudodiaptomus inopinus across the North American Pacific Coast

The rate of aquatic invasions by planktonic organisms has increased considerably in recent decades. In order to effectively direct funding and resources to control the spread of such invasions, a methodological framework for identifying high-risk transport vectors, as well as ruling out vectors of lesser concern will be necessary. A number of estuarine ecosystems on the North American Pacific Northwest coast have experienced a series of high impact planktonic invasions that have slowly unfolded across the region in recent decades, most notably, that of the planktonic copepod crustacean Pseudodiaptomus inopinus. Although introduction of P. inopinus to the United States almost certainly occurred through the discharge of ballast water from commercial vessels originating in Asia (the species' native range), the mechanisms and patterns of subsequent spread remain unknown. In order to elucidate the migration events shaping this invasion, we sampled the genomes of copepods from seven invasive and two native populations using restriction-site associated DNA sequencing. This genetic data was evaluated against spatially-explicit genetic simulation models to evaluate competing scenarios of invasion spread. Our results indicate that invasive populations of P. inopinus exhibit a geographically unstructured genetic composition, likely arising from infrequent and large migration events. This pattern of genetic patchiness was unexpected given the linear geographic structure of the sampled populations, and strongly contrasts with the clear invasion corridors observed in many aquatic systems

Opportunistic infections and AIDS malignancies early after initiating combination antiretroviral therapy in high-income countries

Background: There is little information on the incidence of AIDS-defining events which have been reported in the literature to be associated with immune reconstitution inflammatory syndrome (IRIS) after combined antiretroviral therapy (cART) initiation. These events include tuberculosis, mycobacterium avium complex (MAC), cytomegalovirus (CMV) retinitis, progressive multifocal leukoencephalopathy (PML), herpes simplex virus (HSV), Kaposi sarcoma, non-Hodgkin lymphoma (NHL), cryptococcosis and candidiasis. Methods: We identified individuals in the HIV-CAUSAL Collaboration, which includes data from six European countries and the US, who were HIV-positive between 1996 and 2013, antiretroviral therapy naive, aged at least 18 years, hadCD4+ cell count and HIV-RNA measurements and had been AIDS-free for at least 1 month between those measurements and the start of follow-up. For each AIDS-defining event, we estimated the hazard ratio for no cART versus less than 3 and at least 3 months since cART initiation, adjusting for time-varying CD4+ cell count and HIV-RNA via inverse probability weighting. Results: Out of 96 562 eligible individuals (78% men) with median (interquantile range) follow-up of 31 [13,65] months, 55 144 initiated cART. The number of cases varied between 898 for tuberculosis and 113 for PML. Compared with non-cART initiation, the hazard ratio (95% confidence intervals) up to 3 months after cART initiation were 1.21 (0.90-1.63) for tuberculosis, 2.61 (1.05-6.49) for MAC, 1.17 (0.34-4.08) for CMV retinitis, 1.18 (0.62-2.26) for PML, 1.21 (0.83-1.75) for HSV, 1.18 (0.87-1.58) for Kaposi sarcoma, 1.56 (0.82-2.95) for NHL, 1.11 (0.56-2.18) for cryptococcosis and 0.77 (0.40-1.49) for candidiasis. Conclusion: With the potential exception of mycobacterial infections, unmasking IRIS does not appear to be a common complication of cART initiation in high-income countries