Physicochemical properties and 3D geostatistical simulations of the Herten and the Descalvado aquifer analogs

This data set presents a comprehensive characterisation of the sedimentary structures from important groundwater hosting formations in Germany (Herten aquifer analog) and Brazil (Descalvado aquifer analog). Multiple 2-D outcrop faces are described in terms of hydraulic, thermal and chemical properties and interpolated in 3D using stochastic techniques. For each aquifer analog, multiple 3D realisations of the facies heterogeneity are provided using different stochastic simulations settings. These are unique analogue data sets that can be used by the wider community to implement approaches for characterising aquifer formations.

Physicochemical sea ice and water characteristics near Point Barrow 2005-2006

Photosynthetic parameters of phytoplankton and sea ice algae from landfast sea ice of the Chukchi Sea off Point Barrow, Alaska, were assessed in spring 2005 and winter through spring 2006 using Pulse Amplitude Modulated (PAM) fluorometry including estimates of maximum quantum efficiency (Fv/Fm), maximum relative electron transport rate (rETRmax), photosynthetic efficiency (alpha), and the photoadaptive index (Ek). The use of centrifuged brine samples allowed to document vertical gradients in ice algal acclimation with 5 cm vertical resolution for the first time. Bottom ice algae (0-5 cm from ice-water interface) expressed low Fv/Fm (0.331-0.426) and low alpha (0.098-0.130 /(µmol photons/m**2/s)) in December. Fv/Fm and alpha increased in March and May (0.468-0.588 and 0.141-0.438 /(µmol photons/m**2/s), respectively) indicating increased photosynthetic activity. In addition, increases in rETRmax (3.3-16.4 a.u.) and Ek (20-88 µmol photons/m**2/s) from December to May illustrates a higher potential for primary productivity as communities become better acclimated to under-ice light conditions. In conclusion, photosynthetic performance by ice algae (as assessed by PAM fluorometry) was tightly linked to sea ice salinity, temperature, and inorganic nutrient concentrations (mainly nitrogen).

Physicochemical and photosynthetic characteristics of water samples obtained during a CCGS Amundsen cruise in 2008

During summer 2008, as part of the Circumpolar Flaw Lead system study, we measured phytoplankton photosynthetic parameters to understand regional patterns in primary productivity, including the degree and timescale of photoacclimation and how variability in environmental conditions influences this response. Photosynthesis-irradiance measurements were taken at 15 sites primarily from the depth of the subsurface chlorophyll a (Chl a) maximum (SCM) within the Beaufort Sea flaw lead polynya. The physiological response of phytoplankton to a range of light levels was used to assess maximum rates of carbon (C) fixation (P*m), photosynthetic efficiency (alpha*), photoacclimation (Ek), and photoinhibition (beta*). SCM samples taken along a transect from under ice into open water exhibited a >3-fold increase in alpha* and P*m, showing these parameters can vary substantially over relatively small spatial scales, primarily in response to changes in the ambient light field. Algae were able to maintain relatively high rates of C fixation despite low light at the SCM, particularly in the large (>5 µm) size fraction at open water sites. This may substantially impact biogenic C drawdown if species composition shifts in response to future climate change. Our results suggest that phytoplankton in this region are well acclimated to existing environmental conditions, including sea ice cover, low light, and nutrient pulses. Furthermore, this photoacclimatory response can be rapid and keep pace with a developing SCM, as phytoplankton maintain photosynthetic rates and efficiencies in a narrow ''shade-acclimated'' range.

Physicochemical characteristics and protist occurrence at stations sampled in 2007/2008 in the eastern Beaufort Sea

This study documents, for the first time, the abundance and species composition of protist assemblages in Arctic sea ice during the dark winter period. Lack of knowledge of sea-ice assemblages during the dark period has left questions about the retention and survival of protist species that initiate the ice algal bloom. Sea-ice and surface water samples were collected between December 27, 2007 and January 31, 2008 within the Cape Bathurst flaw lead, Canadian Beaufort Sea. Samples were analyzed for protist identification and counts, chlorophyll (chl) a, and total particulate carbon and nitrogen concentrations. Sea-ice chl a concentrations (max. 0.27 µg/l) and total protist abundances (max. 4 x 10**3 cells/l) were very low, indicating minimal retention of protists in the ice during winter. The diversity of winter ice protists (134 taxa) was comparable to spring ice assemblages. Pennate diatoms dominated the winter protist assemblage numerically (averaging 77% of total protist abundances), with Nitzschia frigida being the most abundant species. Only 56 taxa were identified in surface waters, where dinoflagellates were the dominant group. Our results indicate that differences in the timing of ice formation may have a greater impact on the abundance than structure of protist assemblages present in winter sea ice and at the onset of the spring ice algal bloom.

Physicochemical parameters of water sample the four coastal lagoons at the Peninsula of Yucatan

Study sites. Samples of surface water were taken from 4 coastal lagoons on the Yucatan Peninsula in Mexico: Celestun (20° 45' N - 90° 22' W), Chelem (21° 15' N - 89° 45' W), Rosada Lagoon (21º 19' N - 89º 19' W), and Sabancuy Estuary (18° 58' N - 91° 12' W). The sampling was performed from august to October of 2011 (Chelem 08/24; Laguna Rosada 09/06; Celestún 09/28; Sabancuy 10/25). The sampling was random without replacement and 10 samples of surface water were collected along a transect parallel to the coastal axis. Samples were deposited in sterile plastic bottles and conserved in refrigeration at 4°C. All samples were processed within 24 hours after sampling. According to the Mexican laws and regulations no permissions are required to obtain water and sediment samples from open public areas. Analysis of environmental and physicochemical parameters. Determinations of the environmental parameters were performed with a Hach 5465000 model 156 multi-parameter measuring instrument. The Lorenzen method was used to determine chlorophyll-a (21) with 90% acetone and the concentration was calculated according to the formula: Chla= 27.63 (OD665o - OD665a)(VA)/VM x L Where, OD665o: absorbance at 665 nm before acidification; OD665a: absorbance at 665 nm after acidification; VA: volume (ml) of acetone for extraction; VM: volume (ml) of filtered water; L: length (cm) of the photometric cell. Determinations of the physicochemical parameters (silicates, phosphates, nitrates, nitrites and ammonia) were performed using the spectrophotometric techniques described and modified by Strickland and Parsons (1972).

Physicochemical properties and fish occurrence in 35 Icelandic lakes housing Arctic charr (Salvelinus alpinus)

The common occurrence of parallel phenotypic patterns suggests that a strong relationship exists between ecological dynamics and micro-evolution. Comparative studies from a large number of populations under varying sets of ecological drivers could contribute to a better understanding of this relationship. We used data on morphology of arctic charr (Salvelinus alpinus) and ecological factors from 35 Icelandic lakes to test the hypothesis that morphological patterns among monomorphic charr populations from different lakes are related to interlake variation in ecological characteristics. There is extensive phenotypic diversity among populations of Icelandic charr, and populations are easily distinguished based on overall body morphology. The results obtained in the present study showed that the morphological diversity of charr was related to large-scale diversity in lake ecology. Variation in charr morphology was related to water origin (e.g. spring fed versus run-off), bedrock age, and fish community structure. The present study shows how various ecological factors can shape the biological diversity that we observe.