Dissolved trace element concentrations in the East River-Long Island Sound system: relative importance of autochthonous versus allochthonous sources.

Dissolved trace metal (Ag, Cd, Cu, Fe, Ni, Pb, and Zn), inorganic nutrient (NO3, NH4, PO4, H4SiO4), and DOC concentrations were measured at 43 stations during low (July 2000) and high (April 2001) river discharge conditions in surface waters of Long Island Sound (LIS). To evaluate the impact of fluvial sources to the total metal budget of the sound, samples were collected from major tributaries discharging into LIS (Thames, Quinnipiac, Housatonic, Connecticut, and East Rivers). To compare LIS with other coastal embayments, samples were also collected from five LIS coastal embayments (Manhassett Bay, Huntington Harbor, Oyster Bay, Hempstead Harbor, and Port Jefferson Harbor), which are monitored by the U.S. National Status and Trends Program. Metal and nutrient distributions identified two biogeochemical regimes within LIS: an area of relatively high nutrient and metal concentrations in the East River/Narrows region in western LIS and an area in the eastern region of the sound that had comparatively lower concentrations. Mass balance estimates indicated that, during low flow conditions, the East River was the dominant allochthonous source of most trace metals (Ag, Cd, Cu, Ni, Zn) and inorganic nutrients (NO3 and PO4); during high flow conditions, the most influential source of these constituents was the Connecticut River. Mass balance estimates also evidenced a large autochthonous source of Cu, Ni, and Zn, as their spatial distributions displayed elevated concentrations away from point sources such as the East River. Principal component analysis suggested that metal and nutrient distributions in the LIS system were influenced by different seasonal processes: remobilization from contaminated sediments, anthropogenic inputs from sewage discharges and phytoplankton scavenging during the spring freshet, and benthic remobilization during summer conditions.

Twelve years of contemporary armor evolution in a threespine stickleback population.

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.