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A 3-dimensional hydrodynamic−ecological model system (SINMOD) was used to estimate the full-scale cultivation potential of the brown alga Saccharina latissima in integrated multi-trophic aquaculture (IMTA) with Atlantic salmon Salmo salar. A previously developed model for the frond size and composition (carbon and nitrogen content) of S. latissima sporophytes was adjusted to data from an outdoor mesocosm growth experiment and then coupled and run online with the 3-dimensional model system. Results from simulations were compared with data from an IMTA field experiment, providing partial validation of the hydrodynamic-ecologicalkelp model system. The model system was applied to study the large-scale cultivation potential of S. latissima in IMTA with salmon and to quantify its seasonal bioremediation potential. The results suggest a possible yield of 75 t fresh weight S. latissima ha −1 in 4 mo (February to June) and about 170 t fresh weight ha −1 in 10 mo (August to June). The results further suggest that the net nitrogen consumption of a 1 ha S. latissima installation in the vicinity of a fish farm producing approximately 5000 t salmon in a production cycle is about 0.36 (0.15) t NH 4 + -N, or a removal of 0.34% (0.41%) of the dissolved inorganic nitrogen effluent with a cultivation period from August (February) to June. Due to the differing seasonal growth patterns of fish and kelp, there was a mismatch between the maximum effluent of NH 4 + -N from the fish farm and the maximum uptake rates in S. latissima.

Colored Dissolved Organic Matter (CDOM) is an important optical constituent in seawater, which significantly attenuates the violet to blue portion of visible light. Thus, CDOM reduces the radiation energy available to phytoplankton and affects remote-sensing signals. We present data from two cruises transecting the Polar Front from Atlantic to Arctic waters in the Barents Sea, in 2007 and 2008. The latter took place during the spring bloom of phytoplankton in May (0.2 b [Chl a] b 13 mg m −3) and the former during August (max. [Chl a] b 2 mg m −3). Absorption by CDOM at 443 nm ranged from 0.004 to 0.080 m −1 during May and from 0.006 to 0.162 m −1 during August. Surprisingly, CDOM absorption differed little across the Polar Front, but was higher during August than during May (P b 0.05). The slope coefficient of the absorption spectra (S) ranged from 0.008 to 0.036 nm −1 (mean = 0.015 nm − 1) including both cruises, and varied little across the Front (P > 0.05). The CDOM remote sensing product from GlobColour correlated well with sampled data (R 2 = 0.73) during May. However, during August the satellite product performed poorly (R 2 = 0.02) due to extensive scattering caused by coccolithophorids in the Atlantic Water. The CDOM pool was of autochthonous (marine) origin as characterized from its S vs. absorption relationship. Modeling showed that CDOM, on average, contributed equally to the light absorption as did phytoplankton (at 1 mg Chl a m −3), and thereby reduces the amount of light available for primary production.

To study the use of nuclear magnetic resonance (NMR) spectroscopy as a method of classification, we performed high-resolution magic angle spinning proton (HR MAS 1 H) NMR spectroscopy analysis of whole-cell samples of Dunaliella sp. (Chlorophyceae), Amphidinium carterae (Dinophyceae), Phaeodactylum tricornutum and Thalassiosira pseudonana (Bacillariophyceae). Emphasising the potential use of NMR spectroscopy as a routine analysis of microalgae we chose a straightforward procedure for culturing and harvesting, without extraction or radioactive labelling. We obtained well-resolved HR MAS 1 H NMR spectra from the 4 algae, despite the fact that our samples contained whole cells and some residual sea water. Selected parts of 5 replicate spectra from each microalga were used as input in 2 multivariate pattern-recognition strategies (principal component analysis and fuzzy clustering), both analyses showing clear grouping of the different species. Two spectra from a previous sample run (cultures grown under the same conditions) were also included, and both were correctly classified. We therefore consider HR MAS 1 H NMR spectroscopy to be a potential method of classification for microalgae, with statistical data processing indicating replicability and robustness of the method.

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The present study investigated the drag increase on aquaculture nets due to biofouling of the colonial hydroid Ectopleura larynx. It had two main parts: firstly the growth characteristics of E. larynx were investigated by use of field tests at a Norwegian aquaculture site; secondly the hydrodynamic drag on the fouled twines was studied in a towing tank by using fabricated models of net twines with artificial hydroid fouling. In the field tests, the growth of the hydroids was first measured after three weeks of immersion and then again after six weeks. During this interval, the density of hydroids and the thickness of the hydroid stem were almost constant (1.4 hydroids/mm and 0.29 mm, respectively), while the average length of the hydroids increased from 6.4 to 11.2 mm. The hydroid length followed a Rayleigh distribution, while the thickness was normal (Gaussian) distributed. Replicas of twines with three different levels of hydroid growth were made (1.5 hydroids/mm twine, hydroid length 9 mm, 16 mm and 20 mm), and the drag on these twines was measured at different towing velocities (0.1 to 1.4 m/s) and with different twine configurations. For the twine with the shortest hydroids (9 mm), the drag was from 1.5 times (Re=4000) to 2.2 times (Re=1000) the drag on a clean twine. For the longest hydroids (21 mm), the drag was 2 times and 3.8 times, respectively.

In the presented study a hyperspectral imager (400-700 nm) mounted on a stereo-microscope was used to separate differences in in vivo optical signatures identifying different pigment groups of bloom-forming phytoplankton and macroalgae by comparing spectral absorption, transmittance, and reflectance from 400-700 nm. The results show that the hyperspectral imager could be used to detect spectral characteristics on the microm level to calibrate, validate, identify, and separate objects with differences in color (optical fingerprinting). This information can be used for pigment group specific taxonomy (bio-optical taxonomy), eco-physiological information (e.g., health status), monitoring, and mapping applications.

We present an easy and efficient approach for remote sensing of ocean color, relevant for monitoring and management of kelp forest and bottom substrate with a cheap custom made hyperspectral imager. Remote sensing of ocean color was performed in the Kongsfjord, Spitsbergen (79° N and 12° E) from an airplane (2950 m altitude) equipped with a hyperspectral imager, giving monochromatic images (425-825 nm) using the push broom technique, captured with custom designed software in 5 nm steps. Synchronously in situ measurements of upwelling spectral irradiance, (E u (λ)) (λ = 350-950 nm) measured at 30 cm depth were performed as a reference for the remotely sensed images. Surface water samples were taken for enumeration and identification of organic (plankton), inorganic particles, and colored dissolved organic matter. For identification and classification of kelp and bottom substrate, Bayesian supervised classification and a differential histogram equalization technique were used and compared. Both techniques gave successful discrimination between kelp and bottom substrate in shallow water above the Secchi depth (<19 m). The imager could easily be implemented for other applications such as detection and monitoring of phytoplankton blooms, suspended matter, and colored dissolved organic matter in surface waters, especially in connection with environmental and aquaculture management.