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Numerous studies have documented declines in the abundance of reefbuilding corals over the last several decades and in some but not all cases, phase shifts to dominance by macroalgae have occurred. These assessments, however, often ignore the remainder of the benthos and thus provide limited information on the present-day structure and function of coral reef communities. Here, using an unprecedentedly large dataset collected within the last 10 years across 56 islands spanning five archipelagos in the central Pacific, we examine how benthic reef communities differ in the presence and absence of human populations. Using islands as replicates, we examine whether benthic community structure is associated with human habitation within and among archipelagos and across latitude. While there was no evidence for coral to macroalgal phase shifts across our dataset we did find that the majority of reefs on inhabited islands were dominated by fleshy nonreef-building organisms (turf algae, fleshy macroalgae and non-calcifying invertebrates). By contrast, benthic communities from uninhabited islands were more variable but in general supported more calcifiers and active reef builders (stony corals and crustose coralline algae). Our results suggest that cumulative human impacts across the central Pacific may be causing a reduction in the abundance of reef builders resulting in island scale phase shifts to dominance by fleshy organisms.

The catalytic co-pyrolysis of a seaweed biomass, Laminaria japonica, and a typical polymer material, polypropylene, was studied for the first time. A mesoporous material Al-SBA-15 was used as a catalyst. Pyrolysis experiments were conducted using a fixed-bed reactor and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). BET surface area, N2 adsorption-desorption isotherms, and NH3 temperature programmed desorption were measured to examine the catalyst characteristics. When only L. japonica was pyrolyzed, catalytic reforming slightly increased the gas yield and decreased the oil yield. The H2O content in bio-oil was increased by catalytic reforming from 42.03 to 50.32 wt% due to the dehydration reaction occurring on the acid sites inside the large pores of Al-SBA-15. Acids, oxygenates, mono-aromatics, poly aromatic hydrocarbons, and phenolics were the main components of the bio-oil obtained from the pyrolysis of L. japonica. Upon catalytic reforming over Al-SBA-15, the main oxygenate species 1,4-anhydro-d-galactitol and 1,5-anhydro-d-manitol were completely removed. When L. japonica was co-pyrolyzed with polypropylene, the H2O content in bio-oil was decreased dramatically (8.93 wt% in the case of catalytic co-pyrolysis), contributing to the improvement of the oil quality. A huge increase in the content of gasoline-range and diesel-range hydrocarbons in bio-oil was the most remarkable change that resulted from the co-pyrolysis with polypropylene, suggesting its potential as a transport fuel. The content of mono-aromatics with high economic value was also increased significantly by catalytic co-pyrolysis.

Growth, proximate composition, chlorophyll a, and carotenoid content were estimated in static cultures of micro alga Dunaliella salina (Dunal) Teod (Chlorophycea: Dunaliellaceae) to compare the quality and quantity of biomass produced with seaweed liquid fertilizer (SLF) against Walne’s medium. Culture of micro algae was performed with controlled temperature of 27 ± 1 °C, salinity of 33, and an irradiance of 120 ± 3 μ mol m–2 s –1, and daily samples were taken to estimate the above-mentioned parameters. Mean cellular density from samples of both medium were similar and growth rates were 0.44 and 0.42 doubling per day, respectively.

Maximum values of protein content 5.2 and 5.5 pg per cell were estimated on day 5 in Walne’s medium and SLF, respectively. Carbohydrate and lipid content decreased during the first 4 days corresponding to the culture exponential growth. Higher carbohydrate content was found in both media during the first 2 days and thereafter reduced partially compared to their concentrations. Generally lipid contents in cultures with SLF were significantly higher (P ≤0.05) compared to Walne’s medium. Both pigments also increased exponentially and their concentration was same in both experiments. In conclusion, all the parameters tested were similar when using either media, and hence SLF can be used as an alternate media for micro algal culture.

Production of seaweeds by culture practices is done generally by vegetative propagation of small fragments of some agarophytes, alginophytes and carrageenophytes. Gracilaria edulis and Celidiella acerosa reach harvestable size after 2 and 21/2 months respectively when the seaweed is harvested and processed for agar extraction. India has a good scope for starting a seaweed culture industry based on the know-how available at the Central Marine Fisheries Research Institute.