Spatial and seasonal variability of fractionated phytoplankton biomass and primary production in the frontal region of the Northern Adriatic Sea

Spatial and seasonal patterns of variation of fractionated phytoplankton biomass and primary production and their relationships with nutrient concentrations were analyzed along an inshore - offshore gradient and in relation to the presence of a frontal system in the Northern Adriatic Sea. Sampling was carried out in winter and summer during four oceanographic cruises (June 1996 and 1997, February 1997 and 1998) as part of the PRISMA II project. Water samples for determining nutrient concentrations, phytoplankton biomass (as Chla) and primary production (as 14 C assimilation) were collected at five optical depths. Sampling stations were located along 2 or 4 parallel transects arranged perpendicularly to the shoreline and the frontal system. The transects were located at such a distance from the coast that the frontal system crossed them at their halfway point. Total dissolved nitrogen (TDN) and total dissolved phosphorus concentrations (TDP) were 12.41 ± 3 .95 mM and 0.146 ± 0 .070 mM, respectively. The values in the two seasonal periods were similar, decreasing along the inshore-offshore gradient. Values for phytoplankton biomass and primary productionwere higher in the winter than the summer cruises, and decreased, in both seasonal periods, along the inshore / offshore gradient. Moreover, in both seasonal periods, picophytoplankton dominated both biomass and productivity, (56% and 44%, respectively) at stations beyond the frontal system, while microphytoplankton was more important at stations inside it (44% and 44%, respectively). Total phytoplankton biomass and primary production were directly related to nutrient concentrations. Regarding size classes, significant patterns of variation with nutrients were observed particularly for biomass. The results indicate that the size structure and function of phytoplankton guilds seem to be mediated by nutrient inflow, as well as by competitive interaction among size fractions

Biovolume determination of phytoplankton guilds in transitional water ecosystems of Mediterranean Ecoregion

1 - Conceptually, morphometric measurements of phytoplankton guilds seem to have major advantages as descriptors of the ecological status of transitional water ecosystems (TW) with respect to classical taxonomic descriptors. However, at present, standardized or common methodologies for the use of morphometric descriptors do not exist. 2 - This paper aims to provide a starting point for the activation of standardized methods for the determination of morphometric descriptors of phytoplankton as a quality element in TW in accordance with the new directive of WFD 2000/60/EU. 3 - Phytoplankton biovolume is one of the most studied morphometric descriptors. It can be estimated by associating the algae with similar geometric forms and determining the volume of these by measuring the linear dimensions required for its calculation under the microscope. However, the lack of a standardized set of geometric forms and equations for calculating biovolume causes difficulties and produces data that are not comparable. 4 - A set of geometric models is suggested here for calculating the cell biovolumes of 201 phytoplankton genera found in transitional water ecosystems of Mediterranean Ecoregion. The equations were designed to minimize the effort of microscopic measurements. The main methodological problems, and the similarities and differences between our own and previously published proposals are discussed

When Sunday meets Monday : American evangelicals, their Gospel, and the workplace

The relationship between American evangelicalism and contemporary society is a complex one. By looking at evangelical attitudes toward work, this study aspires to at least begin untangling some of this convoluted relationship. Drawing upon history, theology, and sociology, especially ethnographic methods and interviews, this study argues that when American evangelicals think about engaging their workplaces evangelism takes center stage. While, at a glance, this gospel and the effort to share it may seem at odds with contemporary sensibilities, a closer examination reveals certain concessions to culture among the evangelicals studied. More specifically, evangelical thoughts concerning work reveal that two central features of the gospel being shared, namely, sin and redemption, appear to be morphing in ways more congruent with contemporary culture. The evangelical relationship with their surrounding world reveals a tension between cultural distance and distinction, on the one hand, and cultural nearness or congruence, on the other. This tension does not mean that evangelicalism is necessarily on track to fail, as secularization proponents might argue. On the contrary, American evangelicalism, it will be suggested, actually finds a degree of sustainability in the world thanks to this tension. Moreover, some of this accommodation to culture accentuates important features indigenous to the evangelical tradition. Evangelical attitudes toward work, then, point to a complex and surprising relationship between evangelicalism and contemporary society.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Functional ecology of the marine benthos : do species matter?

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Nutrient loading and spatial-temporal dynamics of phytoplankton guilds in a Southern Italian coastal lagoon (Lake Alimini Grande-Otranto, ITALY).

The importance of external and internal P-loading to the structural organization and dynamics of phytoplankton guilds in a Southern Italy coastal lagoon (Lake Alimini Grande) was investigated. To this end, phosphorus external loading through localized freshwater inputs was measured, P-release through detritus decomposition on sediments was evaluated, and phytoplankton abundance, biomass and taxonomic composition were quantified at 33 sites and 12 sampling times from September 1998 to September 1999. P-loading in the area was greater in the winter (26.5 µM P m−2 d−1) than in the summer (18.4 µM P m−2 d−1). In the winter, external inputs were 61.7% of the total, while in summer, internal inputs accounted for 99.8% of the total. Phytoplankton biomass was related to P inputs. In particular, the spatial distribution of phytoplankton biomass was related to external inputs in winter-spring, and to internal inputs in summer-autumn. A total of 228 phytoplankton taxa were identified of which 13 taxa accounted for more than 80% of phytoplankton abundance. The spatial and temporal dynamics of 13 taxa were related to P-availability and habitat heterogeneity