Temporal variation of phytoplankton in two neighbouring Mediterranean shallow lakes in Doñana National Park (Spain)This study was aimed at describing the phytoplankton dynamics and structure of two eutrophic to hypereutrophic Mediterranean shallow lakes (Santa Olalla and Dulce). The two systems are close together and can function as one water body at times of heavy rainfall, but once separated, they evolve differently. The Shannon diversity index was low for both shallow lakes (average values of 1.11 in Santa Olalla and 1.79 in Dulce). The average phytoplankton Chl a concentrations and primary production rates were very high, although slightly higher in Santa Olalla (365.2 mg m -3 and 1.29 g C m -3 h -1 , respectively) than in Dulce (230 mg m -3 and 0.88 g C m -3 h -1 ). Phytoplankton variation in the lakes was related to shifts in the physical and chemical features of lake water as well as hydrological conditions, a finding that is corroborated by the canonical correspondence analysis results, which showed a different pattern of evolution in each system. Eight functional groups were found in Santa Olalla (D, H 1 , J, K, M, S 1 , W 2 and Y), although the D, W 2 and Y groups were only predominant during the first four months of the study. For the rest of the period, the system was particularly dominated by the H 1 , K and S 1 groups. Dulce exhibited a more complex distribution of phytoplankton functional groups over time. Ten functional groups were observed in this system (D, H 1 , J, K, M, P, S 1 , S 2 , W 2 and Y). Some characteristics of these systems, such as rapid water volume fluctuations, low light penetration and low concentration of inorganic nutrients, are stressful conditions for phytoplankton, which may account for the low phytoplankton diversity and the equilibrium phases recorded for many months in both wetlands.
The California sea lion is one of the few wild mammals prone to develop cancer, particularly urogenital carcinoma (UGC), whose prevalence is currently estimated at 25% of dead adult sea lions stranded along the California coastline. Genetic factors, viruses and organochlorines have been identified as factors that increase the risk of occurrence of this pathology. Given that no cases of UGC have as yet been reported for the species along its distribution in Mexican waters, the potential relevance of contaminants for the development of urogenital carcinoma is highlighted even more as blubber levels of organochlorines are more than two orders of magnitude lower in the Gulf of California and Mexican Pacific than in California. In vitro studies have shown that organochlorines can modulate anti-viral and tumor-surveillance activities of NK and cytotoxic T-cells of marine mammals, but little is known about the activity of these effectors in live, free-living sea lions. Here, we examine leukocyte transcriptional profiles of free-ranging adult California sea lions for eight genes (Eomes, Granzyme B, Perforin, Ly49, STAT1, Tbx21, GATA3, and FoxP3) selected for their key role in anti-viral and tumor-surveillance, and investigate patterns of transcription that could be indicative of differences in ecological variables and exposure to two oncogenic viruses: sea lion type one gammaherpesvirus (OtHV-1) and sea lion papillomavirus type 1 (ZcPV-1) and systemic inflammation. We observed regional differences in the expression of genes related to Th1 responses and immune modulation, and detected clear patterns of differential regulation of gene expression in sea lions infected by genital papillomavirus compared to those infected by genital gammaherpesvirus or for simultaneous infections, similar to what is known about herpesvirus and papillomavirus infections in humans. Our study is a first approach to profile the transcriptional patterns of key immune effectors of free-ranging California sea lions and their association with ecological regions and oncogenic viruses. The observed results add insight to our understanding of immune competence of marine mammals, and may help elucidate the marked difference in the number of cases of urogenital carcinoma in sea lions from US waters and other areas of their distribution.
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