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Loberg Lake, Alaska was colonized by sea-run Gasterosteus aculeatus between 1983 and 1988, after the original stickleback population was exterminated. Annual samples from 1990 to 2001 reveal substantial evolution of lateral plate (armor) phenotypes. The 1990 sample was nearly monomorphic for the complete plate morph, which is monomorphic in local sea-run populations; the low plate morph, which is usually monomorphic in local freshwater populations, was absent. By 2001, the frequency of completes had declined to 11%, and lows had increased to 75%. The partial plate morph and two unusual intermediate plate phenotypes were generally rare, but occurrence of the intermediates was unexpected. These intermediate phenotypes rarely occur in other, presumably older, polymorphic populations. When low morphs first appeared, they averaged 6.8 plates per side, indicating that the ancestral plate number of low morphs is high, and their mean has subsequently declined. Contemporary evolution in this population indicates that threespine stickleback adapt to freshwater habitats within decades after invasion from the ocean, and thus phenotypes in most populations are adapted to current conditions.

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Although nutrients and grazing both contribute to the formation of harmful algal blooms, research on these events has rarely considered both factors simultaneously. To ascertain the impact of nutrients and grazing on brown tides of Aureococcus anophagefferens, nutrient bioassays were conducted in parallel with dilution‐style microzooplankton grazing experiments during an intense bloom that occurred throughout Great South Bay (GSB), New York, in fall of 1999. During the study, Aureococcus represented between 25 and 85% of phytoplankton biomass and attained peak cell densities > 6 × 105 cells ml−1. Concentrations of dissolved organic carbon (DOC) and nitrogen (DON) in GSB were high (mean = 430 µM and 32 µM, respectively) during the bloom, while dissolved inorganic nitrogen (DIN) levels were low (mean = 2.5 µM). Although the experimental additions of nitrogen (nitrate or urea) typically enhanced the growth rates of the non‐brown tide phytoplankton community, such additions often had no impact on, or decreased, growth rates of Aureococcus relative to unamended control treatments. These observations suggest that growth of non‐brown tide phytoplankton depended on ambient N supply rates, while Aureococcus experienced nutrient replete growth. Dilution experiments indicated that microzooplankton grazing rates on A. anophagefferens were significantly lower than those on other algal populations. This reduced grazing pressure contributed toward higher net growth rates for Aureococcus relative to non‐brown tide phytoplankton. In sum, these results demonstrate that both top‐down (low grazing mortality rates) and bottom‐up (a high DOC/DON, low DIN nutrient regime) factors can contribute to the proliferation of brown tide blooms in New York waters.

Our understanding of glacial flour dust storm delivery of iron to the Gulf of Alaska (GoA) is limited. Here we interpret concurrent time series satellite, meteorological, and aerosol geochemical data from the GoA to examine how interannual variability in regional weather patterns impacts offshore aerosol glacial Fe deposition. In 2011, when a northerly Aleutian Low (AL) was persistent during fall, dust emission was suppressed and highly intermittent due to prevalent wet conditions, low winds, and a deep early season snowpack. Conversely, in 2012, frequent and prolonged fall dust storms and high offshore glacial Fe transport were driven by dry conditions and strong offshore winds generated by persistent strong high pressure over the Alaskan interior and Bering Sea and a southerly AL. Twenty‐five‐fold interannual variability in regional offshore glacial aerosol Fe deposition indicates that glacial dust's impact on GoA nutrient budgets is highly dynamic and particularly sensitive to regional climate forcing.

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Recent analyses suggest that considerable CaCO 3 dissolution may occur in the upper water column of the ocean (< 1500 m). This study uses the distribution of particulate calcium from high-resolution suspended matter sampling along the Climate Variability and Predictability/CO 2 Repeat Hydrography A16N transect in 2003 to estimate CaCO 3 dissolution in the top 1000 m of the North Atlantic. Dissolution rates were also approximated using changes in total alkalinity measurements along isopycnal surfaces. Water masses were found to be undersaturated with respect to aragonite at intermediate depths (400-1000 m) in the eastern tropical North Atlantic. The CaCO 3 dissolution rate in this region is estimated to be 0.9 mmol CaCO 3 m À2 d À1, indicating this region is a hotspot for upper water column CaCO 3 dissolution compared to the Atlantic basin as a whole. Dissolution rates calculated from particulate calcium distributions outside of this region were significantly lower (0.2 mmol CaCO 3 m À2 d À1) and are comparable to previous estimates of CaCO 3 dissolution flux for the Atlantic Ocean. The magnitude of upper water column dissolution rates compared to measured surface ocean CaCO 3 standing stocks suggests that biologically mediated CaCO 3 dissolution may be occurring in the top 1000 m of the Atlantic.