Net primary productivity in Arctic Ocean from Effects of sea ice cover on satellite-detected primary production in the Arctic ocean

Time Monthly NPP, Pg C NPP per open water area, mgC/m2/day Year Annual NPP, PgC Max monthly NPP, Pg C NPP/are

Pairwise comparison using Holm-Sidak method comparing interaction of effects of design (MLHD, BPVD, SD, SUB) and JSM fertilizer concentrations (1X, 2X, 4 X and 8X).

<p>Overall significance level = 0.05. *The mean difference is significant at the 0.05 level.</p

Land-based drip-irrigated culture of <i>Ulva compressa</i>: The effect of culture platform design and nutrient concentration on biomass production and protein content

<div><p>This work developed a laboratory prototype methodology for cost-effective, water-sparing drip-irrigation of seaweeds, as a model for larger-scale, on-land commercial units, which we envision as semi-automated, inexpensive polyethylene sheet-covered bow-framed greenhouses with sloping plastic covered floors, water-collecting sumps, and pumped recycling of culture media into overhead low-pressure drip emitters. Water droplets form on the continually wetted interior plastic surfaces of these types of greenhouses scattering incoming solar radiation to illuminate around and within the vertically-stacked culture platforms. Concentrated media formulations applied through foliar application optimize nutrient uptake by the seaweeds to improve growth and protein content of the cultured biomass. An additional attribute is that seaweed growth can be accelerated by addition of anthropogenic CO₂-containing industrial flue gases piped into the head-space of the greenhouse to reuse and recycle CO₂ into useful algal biomass. This demonstration tested three different drip culture platform designs (horizontal, vertical and slanted) and four increasing fertilizer media concentrations (in seawater) for growth, areal productivity, and thallus protein content of wild-collected <i>Ulva compressa</i> biomass, against fully-submerged controls. Cool White fluorescent lights provided 150–200 μmol photon m^-2 s^-1 illumination on a 12/12 hr day/night cycle. Interactive effects we tested using a four-level single factorial randomized block framework (p<0.05). Growth rates and biomass of the drip irrigation designs were 3–9% day^-1 and 5–18 g m^-2 day^-1 (d.w.) respectively, whereas the fully-submerged control group grew better at 8–11% per day with of 20–30 g m^-2 day^-1, indicating further optimization of the drip irrigation methodology is needed to improve growth and biomass production. Results demonstrated that protein content of <i>Ulva</i> biomass grown using the vertically-oriented drip culture platform and 2x fertilizer concentrations (42:16:36 N:P:K) was 27% d.w., approximating the similarly-fertilized control group. The drip methodology was found to significantly improve gas and nutrient mass transfer through the seaweed thalli, and overall, the labor- and-energy-saving methodology would use a calculated 20% of the seawater required for conventional on-land tank-based tumble culture.</p></div

Land-based drip-irrigated culture of <i>Ulva compressa</i>: The effect of culture platform design and nutrient concentration on biomass production and protein content - Fig 2

<p><b>a)</b> Mean biomass production per day of <i>Ulva compressa</i> grown at different JSM concentrations (1X-8X) on three different cultivation drip-irrigated system cultivations for 15 days in culture; (mean ± st.dev., n = 3 replicates; note: each replicate is an average of 3 trials); <b>b</b>) % Growth rate per day of <i>Ulva compressa</i> grown at different JSM concentrations (mean ± st.dev., n = 3) on three different cultivation spray system cultivation for 15 days.</p

% Protein content of <i>U</i>. <i>compressa</i> grown for 15 days in the different cultivation systems at different concentration of JSM media (mean ± st.dev., n = 3).

<p>% Protein content of <i>U</i>. <i>compressa</i> grown for 15 days in the different cultivation systems at different concentration of JSM media (mean ± st.dev., n = 3).</p

Areal data from summer 2004 and winter 2006 cruises.

<p>All parameters for the summer cruise have been integrated over the entire euphotic layer (1% incident PAR at surface; it was similar to the mixed layer depth or deeper). The winter PP has been integrated over the euphotic layer while other parameters have been integrated over the mixed layer depth (epipelagic) and from there down to 750 m (mesopelagic layer). Averages and standard deviation in parenthesis.</p><p>PP = primary production; BCP = bacterial carbon production; Summer excess DOC = summer dissolved organic carbon values minus average winter constant value (36.5±2.8 µM C s.d.); BCD = bacterial carbon demand (BCP/bacterial growth efficiency); N.D. = not determined.</p>*<p>BCD calculated using a bacterial growth efficiency derived by the curve in ref. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Rivkin1" target="_blank">[20]</a> (∼36% in summer and 39% in winter).</p>**<p>BCD calculated using bacterial growth efficiency of 13% in summer and 6.2% in winter (averaging all data for summer and only HNLC for winter from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Obernosterer1" target="_blank">[12]</a>).</p>§<p>no s.d. reported because the value is derived from a single depth profile.</p>°<p>DOC data for winter are not reported, since they are considered as constant refractory DOC values, and have been used to determine summer excess DOC.</p

Seaweed cultivation platforms of <i>Ulva compressa</i> grown at different JSM (mean ± st.dev., n = 3) concentrations on three different cultivation spray systems for 15 days.

<p><b>a</b>) Multi-Level Horizontal Design (MLHD); <b>b</b>) Bag-Pocket Vertical Design (BPVD), <b>c</b>) Sloped Design (SD), <b>d</b>) Submerged (SUB). Except for the submerged, the other three designs were recirculating systems where the recycled water was pumped back into a reservoir that collects the water and drips back into the culture through gravity at a flow rate of ~5 ml s^-1. Two fluorescent lamps were placed on both sides of the systems set at a 12/12 light/dark cycle. It is a randomized two-factorial design (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199287#pone.0199287.s001" target="_blank">S1 Fig</a> for illustration) to test the design and JSM concentration and its interaction effects with growth performance and protein production.</p

List of GenBank accession number and closest relative to 16S rDNA bacterial sequences obtained from DGGE.

*<p>phylotypes found in both seasons. Ref. = References of the closest relative.</p

Depth profile of bacterial parameters in summer 2004 and winter 2006.

<p>Winter data are from 32 stations from 5 to 400 m; at 6 stations samples were also taken from 750 m. Summer: blue circles = ACC water; red circles = shelf water; green circles = mixed water; empty square = Winter. (Panel A) Bacterial abundance; (panel B) BCP = bacterial carbon production; BCP calculated from ³H-Leucine incorporation, employing a conversion factor of 3.1 kg C per mol of Leu <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Simon1" target="_blank">[17]</a>; (panel C) μ = bacterial growth rate. Cell-specific growth rate calculations assumed 20 fg C per cell <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Lee1" target="_blank">[18]</a>.</p

Biomass data passed normality (Shapiro-Wilk; P = 0.087) after log transformation and equal variance tests (Brown-Forsythe; p = 0.682).

<p>Two-way Analysis of variance of the JSM fertilizer concentrations (1X, 2X, 4 X and 8X) and cultivation design (MLHD, BPVD, SD, SUB) on the daily growth rate of <i>U</i>. <i>compressa</i>. *The mean difference is significant at the 0.05 level.</p