The valorisation of Anaerobic digestion waste streams into algal biomass to produce a protein alternative to soybeans could have significant commercial and environmental value. It has the benefit of alleviating the pressure of disposal of nutrient-rich digestate that is rich in nitrogen, phosphorous and trace metals, while potentially reducing the cost of microalgae production. Currently, the use of soybean protein in animal feed has significant negative environmental issues and high carbon footprint associated with its use. This study investigates three types of Anaerobic digestion to grow Phaeodactylum tricornutum Bohlin microalgae. The results found that the crude protein in all concentrations of cow waste and food waste digestates were found to produce a significantly higher concentration of crude protein in comparison to the F/2 control. In addition, cow waste 1% and pig waste 1% formulations were found to have favourable fatty acid profiles, which has significant health benefits in the livestock industry. There was no significant difference in the total fatty acids found in cow waste 1% and pig waste 1% digestates compared to the F/2 control, which was in the range of 243.4 to 269.4 mg/g (dry weight). The other formulations produced a significantly lower (p < .05) concentration of total fatty acids compared to the control. Cow waste 1% was found to be richer in omega-3, eicosapentaenoic acid, compared to pig waste 1%, however, no significant difference was found between the eicosapentaenoic acid, concentration of cow waste 1% and the F/2 control. Overall, in terms of highest total fatty acids and crude protein, cow waste 1% digestate was found to perform the best out of all the digestates tested, and outperformed the F/2 control in terms of crude protein. The P. tricornutum grown in digestate was also found to bioaccumulate higher levels of calcium. P. tricornutum grown in cow waste 1% digestate could offer an alternative viable locally grown protein source for the animal feed industry, with the added advantage of being rich in eicosapentaenoic acid and calcium.

The Norway lobster, Nephrops norvegicus , is an important fisheries species in the North-East Atlantic area. In some circumstances, mature females of Nephrops norvegicus can resorb their ovary rather than completing spawning, but the implications of this phenomenon to reproductive biology and fisheries sustainability are not known. To understand after effects of ovary resorption, we studied long-term demographic data sets (1994–2017) collected from the western Irish Sea and the North Sea. Our considerations focused on potential correlations among the frequency of resorption, female insemination, and body size of resorbing females. Resorption was continuously rare in the western Irish Sea (less than 1%); whereas much higher rates with considerable year-to-year variation were observed in the North Sea (mean 9%). Resorption started in autumn after the spawning season (summer) had passed. The frequency stayed high throughout winter and declined again in spring. As sperm limitation can occur in male-biased fisheries, we expected a lack of insemination could be responsible for resorption, but affected females were indeed inseminated. Resorbing females were significantly larger than other sexually mature females in the North Sea, but the opposite trend was observed in the western Irish Sea. It is therefore possible that other, environmental factors or seasonal shifts, may trigger females to resorb their ovaries instead of spawning. Resorption may as well represent a natural phenomenon allowing flexibility in the periodicity of growth and reproduction. In this sense, observations of annual versus biennial reproductive cycles in different regions may be closely linked to the phenomenon of ovary resorption.

The widespread introduction of the Pacific oyster, Magallana gigas, has raised concerns regarding its potential impact on the functioning of invaded ecosystems. Concurrently, populations of the European oyster, Ostrea edulis, are in decline. We quantified the functional role of the native oyster, O. edulis, in terms of nutrient cycling and associated infaunal biodiversity and compared it directly to that of the invading oyster, M. gigas. The presence and density of both species were manipulated in the field and we tested for differences in concentration of ammonium, phosphate, total oxidised nitrogen and silicate in pore-water; total organic nitrogen and carbon in sediment; microbial activity; chlorophyll concentration; and the assemblage structure and richness of associated benthic taxa. No differences in nutrient cycling rates or associated benthic assemblages were identified between both oyster species. Nutrient concentrations were mostly affected by differences in oyster density and their significance varied among sampling events. Our findings suggest that M. gigas could compensate for the loss of ecosystem functions performed by O. edulis in areas where native oysters have been extirpated.