Fatty Acid Changes in Nearshore Phytoplankton under Anthropogenic Impact as a Biodiversity Risk Factor for the World’s Deepest Lake Baikal

In this study, we present results on fatty acid analysis of phytoplankton of Lake Baikal, the world’s deepest lake, which differs from other lakes by its oceanic features. Since we used a large-mesh net, the net sample phytoplankton were primarily represented by the large elongated diatom Synedra acus. subsp. radians (Kützing) Skabichevskij. The similar algae composition of net samples of spring season phytoplankton collected at different sites of the lake allows us to compare results of the fatty acid analysis of these samples. The phytoplankton diversity of the sedimentation samples was contrary represented by 32 algae species. There are clear changes in the fatty acid composition of net phytoplankton exposed to anthropogenic impacts of varying intensity. The content of polyunsaturated fatty acids in phytoplankton collected from central stations (pelagic stations at a distance of ~10–30 km from the shoreline) without anthropogenic impact was higher by up to 15% than phytoplankton collected from nearshore stations (littoral stations at a distance of ~0.01–0.05 km from the shoreline) and offshore stations (pelagic stations at a distance of ~3 km from the shoreline). The interlaboratory precision of fatty acid determination of phytoplankton is estimated as ≤10%. We found high content of the lipid peroxidation marker (80–340 μg g−1 of dry weight) in phytoplankton from nearshore and offshore stations with intensive anthropogenic impact. In phytoplankton from central stations, we did not find any lipid peroxidation. Determination of unsaturated fatty acids, coupled with analysis of fatty acid peroxidation products, can be used to evaluate the level of anthropogenic impact in terms of ecological health and biodiversity conservation.

Phytoplankton Biodiversity in Two Tropical, High Mountain Lakes in Central Mexico

Lakes El Sol and La Luna, inside the crater of the Nevado de Toluca volcano, Central Mexico, are the only two perennial high mountain lakes [HML] in the country. HML are considered among the most comparable ecosystems worldwide. These lakes are “extreme” environments with diluted, oligotrophic, and cold waters exposed to high UV radiation doses. In this paper, we document the phytoplankton species inhabiting these two extreme tropical ecosystems. The phytoplankton diversity of Lakes El Sol and La Luna is low compared to the global phytoplankton diversity from other Mexican inland waters. Nonetheless, the phytoplankton diversity turned out to be high compared to other HML worldwide, both temperate and tropical. The phytoplankton community in Lake El Sol was formed by 92 morphospecies and in Lake La Luna by 63; in both, the most diverse groups were Bacillariophyceae and Chlorophyceae. All species found in Lake La Luna were present in Lake El Sol, but 29 species present in Lake El Sol were absent in Lake La Luna. Nevertheless, 57% of the most frequent and abundant taxa in Lake El Sol were rare in La Luna, and 47% of the most frequent and abundant taxa in Lake La Luna were rare in Lake El Sol. Associated with their shallowness and polymictic thermal pattern, 87.5% of the Bacillariophyceae morphospecies are tychoplantonic, while the remaining 12.5% are truly planktonic. Dominant taxa were Chlorophyceae in Lake El Sol and Cyanobacteria in Lake La Luna. The most extreme conditions of Lake La Luna (ultraoligotrophy, very low pH, high ultraviolet radiation) most likely explained the differences in the dominant species composition and lower species richness compared to Lake El Sol. Herein, we provide for the first time a taxonomic list of the phytoplankton community of Lakes El Sol and La Luna. This information constitutes a baseline needed to use these HML as sentinels of global and climate change.

The Effect of Commercial Probiotics on the Phytoplankton Diversity Associated with Biofloc

The intensive aquaculture industry faces two main problems, first, the decrease in the water quality caused by high concentrations of metabolites, and second, the use of low natural food in aquaculture activities with high water exchange intensity. For this reason, efforts are needed to develop biofloc to maximize the contribution of natural food which can increase aquaculture production. The present study aimed to analyze the effect of commercial probiotics on the differences in the phytoplankton diversity associated with biofloc. The fish were divided into three treatment groups. Treatment A involved biofloc formation without using probiotics, treatment B contained biofloc formation using commercial probiotics (Bacillus spp., lactic acid, Lactobacillus spp., Saccharomyces spp. 50/50 feed), and treatment C entailed biofloc formation using commercial probiotics (containing a native microbial consortium, 50/50 feed). The treatment groups were repeated six times so that there were 18 experimental units. The research was conducted from March to April 2015. The results indicated that the administration of probiotics with different types led to insignificant differences among the treatment groups. The highest diversity index value occurred in treatment C on day 34 of the experiment that was equal to 0.49. On the other hand, the highest value of the dominance index (C = 0.99) occurred in treatments A and B on day 21. It can be concluded that the addition of probiotics with different biofloc could result in insignificant phytoplankton diversity. Furthermore, the Nitrogen/Phosphorus (N/P) ratio as a limiting factor for phytoplankton growth indicated different results in each treatment.

Spatiotemporal Variations in Antarctic Protistan Communities Highlight Phytoplankton Diversity and Seasonal Dominance by a Novel Cryptophyte Lineage

The climate-sensitive waters of the West Antarctic Peninsula (WAP), including its many fjords, are hot spots of productivity that support multiple marine mammal species. Here, we profiled protistan molecular diversity in a WAP fjord known for high productivity and found distinct spatiotemporal patterns across protistan groups.

Effects of Vertical Spatial Overlap on Phytoplankton Diversity under Experimentally Altered Lake Stratification Regimes

In phytoplankton communities, competitive exclusion might occur when functionally similar species are impeded from regulating their positions along light and nutrient gradients to reduce niche overlap. Greater spatial overlap (SO) between species due to water column mixing could thus promote competitive exclusion, reducing community taxonomic diversity. However, greater SO could also promote coexistence of functionally different taxa. Using data from a whole-lake experiment, we investigated the effects of SO and other relevant environmental factors on phytoplankton diversity across the water columns of lake basins with different thermocline manipulations. We estimated SO using an in situ fluorometer, and overall community diversity microscopically. Using structured equation models, we estimated directional relationships between phytoplankton diversity, SO, the lake physical structure and the zooplankton community. No significant effect of SO on phytoplankton taxonomic diversity was observed, but higher SO was associated with greater functional diversity. Change in lake physical structure and in the zooplankton community also affected diversity, with a negative response to increased top-down interactions. Overall, despite the fact that the alteration of water column stratification structure and top-down interactions were stronger drivers of phytoplankton diversity in our system, some effect of spatial overlap on the outcome of inferred competitive interactions were observable.

The Effects of Different Water Quality Parameters on Prawn (Macrobrachium Rosenbergii) Yield, Phytoplankton Abundance and Phytoplankton Diversity at New Zealand Prawns Limited, Wairakei, New Zealand

<p>Aquaculture is the fastest growing industry in the food sector and demand for aquaculture products is continuing to grow as many wild stocks from capture fisheries continue to decline. It is imperative that water quality in an aquaculture system is closely controlled in order to maintain the health of the species under culture and maximize production. New Zealand Prawns Limited (NZPL) is an aquaculture facility in Wairakei, New Zealand that cultures the freshwater prawn Macrobrachium rosenbergii. Dramatically reduced yields of prawns have been observed in ponds following periodic blooms of benthic algae. In this study, water quality variables were measured in grow out ponds at 9-11 day intervals. I measured temperature, phytoplankton abundance, phytoplankton diversity, turbidity, and concentrations of ammonia, nitrate, orthophosphate, dissolved oxygen and chlorophyll a. This data was combined with information on pond depth and prawn yield in order to investigate what variables influence the abundance and diversity of phytoplankton, benthic algal blooms and prawn yield. The difficulty of combining scientific endeavour with commercial enterprises resulted in only a small data set being available for analysis but it appears that benthic algal blooms at NZPL may be due to excessive light penetration to the benthos due to shallow pond depths, and reduced shading of the benthos when phytoplankton abundance is low. Low phytoplankton abundance may possibly be a result of low orthophosphate. There was insufficient data to determine what impacts, if any, the variables investigated have on prawn yield or how water quality variables change with time. Future studies and experiments are recommended in order to increase knowledge of farming M. rosenbergii; a valuable crustacean that has been shown to have a lower social and environmental impact than many other more common aquaculture species.</p>