The previously uncharted Afifi brine pool was discovered in the eastern shelf of the southern Red Sea. It is the shallowest brine basin yet reported in the Red Sea (depth range: 353.0 to 400.5 m). It presents a highly saline (228 g/L), thalassohaline, cold (23.3 °C), anoxic brine, inhabited by the bacterial classes KB1, Bacteroidia and Clostridia and the archaeal classes Methanobacteria and Deep Sea Euryarcheota Group. Functional assignments deduced from the taxonomy indicate methanogenesis and sulfur respiration to be important metabolic processes in this environment. The Afifi brine was remarkably enriched in dissolved inorganic carbon due to microbial respiration and in dissolved nitrogen, derived from anammox processes and denitrification, according to high δ15N values (+6.88‰, AIR). The Afifi brine show a linear increase in δ18O and δD relative to seawater that differs from the others Red Sea brine pools, indicating a non-hydrothermal origin, compatible with enrichment in evaporitic environments. Afifi brine was probably formed by venting of fossil connate waters from the evaporitic sediments beneath the seafloor, with a possible contribution from the dehydration of gypsum to anhydrite. Such origin is unique among the known Red Sea brine pools.
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 130:147-155 (1996) - doi:10.3354/meps130147 Herbivory on Posidoniaoceanica: magnitude and variability in the Spanish Mediterranean Cebrián J, Duarte CM, Marbà N, Enríquez S, Gallegos M, Olesen B We examined the leaf age dependence, magnitude and variability of herbivore consumption of Posidoniaoceanica (L.) Delile leaves in the Spanish Mediterranean. Two patterns of herbivore consumption along the life-span of P. oceanica leaves were found, namely a linear and a parabolic curve of cumulative leaf consumption versus leaf age, which are indicative of leaf-age-independent consumption rates and preference for mid-aged leaves, respectively. The fish Boopssalpa contributed about 75% to the total herbivore consumption, and seemed to be responsible for the parabolic pattern of consumption with leaf age. Herbivory appeared to be a minor factor in the control of P. oceanica production since it only accounted, on the average, for about 2% of its leaf production. This percentage tends to increase in the northern populations of the Spanish Mediterranean as a result of the longer leaf life-span and associated higher cumulative consumption values, and the lower leaf production of these populations. It is concluded that, in spite of the low levels of herbivory on P.oceanica in the Mediterranean, this seagrass supports a high herbivore production due to its large primary production. Herbivory . Posidoniaoceanica . Boopssalpa . Spanish Mediterranean Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 130. Publication date: January 11, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.
Abstract. The metabolic balance of the open waters supporting submerged macrophytes of the Doñana marsh (SW Spain) was investigated in spring, when community production is highest. The marsh community was net autotrophic with net community production rates averaging 0.61 g C m−2 d−1, and gross production rates exceeding community respiration rates by, on average, 43%. Net community production increased greatly with increasing irradiance, with the threshold irradiance for communities to become net autotrophic being 42 to 255 μE m−2 s−1, below which communities became net heterotrophic. Examination of the contributions of the benthic and the pelagic compartments showed the pelagic compartment to be strongly heterotrophic (average P/R ratio = 0.27), indicating that the metabolism of the pelagic compartment is strongly subsidised by excess organic carbon produced in the strongly autotrophic benthic compartment (average P/R = 1.58).
Summary Seagrass meadows are important carbon sinks, and they are experiencing a global decline. Restoration of seagrass meadows provides a strategy to mitigate climate change while conserving these important ecosystems. We examined the long‐term carbon sequestration expected for seagrass restoration programmes by developing a model that combined models of patch growth, patch survival in seagrass planting projects and estimates of seagrass CO 2 sequestration per unit area for the five seagrass species commonly used in restoration programmes. The model results indicated that the cumulative C sequestered increased rapidly over time and with planting density to reach an asymptote at a planting density of 100 units ha −1 (or 6 m spacing between units). At this planting density, the modelled cumulative C sequestered ranges from 177 to over 1337 tons CO 2 ha −1 after 50 years. The value corresponding to this carbon sequestration suggests that the costs of seagrass restoration programmes may be fully recovered by the total CO 2 captured in societies with a carbon tax in place, providing additional ecosystem services derived from the role of seagrasses in providing ecosystem services, such as enhanced biodiversity. Synthesis and applications . Seagrass restoration programmes are economically viable strategies to mitigate climate change through carbon sequestration, particularly in subtropical and tropical island states where land‐based options have a limited scope.
We assess leaf herbivory on several populations of four temperate and five tropical seagrass species and examine, along with a compilation of published reports, the extent of herbivory variability and how it affects its general magnitude to help solve the apparent controversy about the importance of herbivory on seagrasses brought out by recent reports. We further test whether herbivory variability is related to differences in leaf specific growth rate (SGR) as a descriptor of leaf nutritional quality for herbivores. The extent of herbivory varied broadly, both within and among species, ranging from negligible values up to 50% of leaf production removed within some species. This variability, along with that shown by other published reports, claim that the classical statement that herbivory represents minor losses of seagrass production, being considered negligible in most cases, can be misleading and lead to the neglect of important seagrass–herbivore interactions. Differences among species in the percentage of leaf production removed were associated with differences in SGR, pointing to herbivore selective feeding upon faster-growing species resulting from their higher nutritional quality. This selection seems to be independent of leaf nutrient concentrations suggesting that, in agreement with past reports, nutrient levels are a poor descriptor of seagrass nutritional quality as most nutrients can be bound to indigestible fibre. No relationship between herbivory intensity and SGR was found among populations of a single species. On the other hand differences among species in the areal flux of production transferred to herbivores seemed related to differences in the level of production attained. These results point out that whereas SGR should be a descriptor of the variability among species in the extent of herbivore pressure (i.e. percentage of production removed), the level of production should be indicative of differences among species in their capacity to support herbivore production (i.e. flux of production channelled).
Objectives: Type 2 diabetes (T2D) is considered one of the most prevalent diseases worldwide. The aim of this study was to analyse the risk of developing T2D in a higher education community of Bragança, North-Eastern Portugal.Methods: The observational, cross-sectional and prospective sample comprised 3021 individuals, aged between 18 and 64 years old, of whom 1759 were women (mean age 24.16 ± 8.80 years) and 1263 were men (mean age 23.37 ± 8.70 years). The Finnish Diabetes Risk Score (FINDRISC) questionnaire was employed to estimate the risk of developing T2D over the next 10 years.Results: The results indicated that approximately 37 (1%) participants in the sample exhibited a high risk of developing T2D, 117 (4%) participants exhibited a moderate risk, 660 (22%) participants exhibited a slight risk, and 2206 (73%) participants exhibited a low risk. A higher T2D risk was observed in the staff group in comparison with the other groups (p < 0.001). Furthermore, body mass index (BMI) and waist circumference (WC) were the variables that most contributed to the increased risk of developing T2D (X2 = 1034.5; p < 0.001).Conclusions: In conclusion, the study reported a low T2D risk for the higher education community of Bragança in the Portuguese North-Eastern region. However, the risk of T2D was found to be higher in the staff group than in the student group. The FINDRISK questionnaire may be applied for the early diagnosis of T2D risk factors.
The annual depositional flux of carbon (C), nitrogen (N), and phosphorous (P) to the sediments under a northeast Spain Posidonia oceanica meadow was evaluated, and the sources and fate of the material deposited elucidated. The annual deposition of carbon represented 198 g C m −2 yr −1 , 72% of which was derived from the seston and 28% from P. oceanica detritus. The depositional flux was poor in nitrogen (13.4 g N m −2 yr −1 ) and phosphorous (2.01 g P m −2 yr −1 ), although comparable to the nutrient inputs required to support the growth of P. oceanica . Remineralization in the sediment only returned 15.6 g C m −2 yr −1 , yielding a net carbon accumulation of 182 g C m −2 yr −1 . Our results show that in the Mediterranean littoral P. oceanica meadows are important sites of net organic carbon burial, derived from sedimented sestonic particles and seagrass detritus.
