Iosu Madariaga

Primary plankton production, respiration and nitrification in a shallow temperate estuary during summer

Abstract Patterns of longitudinal and temporal variation in rates of primary production, respiration and nitrification were investigated in the Urdaibai estuary during August 1994. Rates of primary production, as measured with the 14C technique, varied between 0.002 and 2.828 mg C l−1 d−1. 14C and oxygen based rates of primary production showed a good correlation, but photosynthetic quotients (mean PQ of 2.2) were higher than expected from considerations of the N source used by the algae. Chlorophyll a biomass showed an inverse correlation with salinity and tidal flushing is hypothesized to be a major controlling factor of its spatial variability. Temporal variations in chlorophyll a concentration were associated primarily to changes in the lunar cycle and following rain events. Rates of community respiration varied between 0.154 and 6.857 mg O2 l−1 d−1 and were significantly and positively correlated with both bacterial abundance and chlorophyll a concentration. The relationship between respiration and primary production suggested that respiration rates based on substrates not associated with the autochthonous pelagic primary production increased greatly from the outer to the inner estuary and that the consumption of autotrophic production by heterotrophs in the water column was higher in the less productive outer estuary than in highly productive intermediate and inner areas. Except at the innermost station, temporal variations in respiration rates followed variations in temperature. The ratio of gross primary production to respiration ( GP R ) showed marked spatial and temporal variations, ranging from 0.24 to 17.94. Rates of nitrification, measured as allylthiourea sensitive rates of CO2 fixation, varied from undetectable levels to 9.3 μg C l−1 d−1.In general, highest rates of nitrification were observed at the inner estuary under conditions of elevated ammonia concentration, high bacterial abundance and high turbidity. Rates of nitrification were frequently associated with the > 3 μm size fraction. Oxygen consumed in nitrification was estimated to account on average for 4.7 ± 8.3% of total oxygen consumption.

The Relevance of Local Participatory Scenario Planning for Ecosystem Management Policies in the Basque Country, Northern Spain

As part of the Millennium Ecosystem Assessment in Biscay, Basque Country, we described scenarios for Biscay through 2050 in an integrated and participatory way by downscaling the Millennium Ecosystem Assessment (MA) global scenarios, analyzed how ecosystem services and human well-being might change in a range of plausible futures, identified management strategies for the territory through a backcasting process, and explored the relevance of scenarios to policy making. Our intention was to strengthen the link to policy making and to achieve a real implementation of our research results in ecosystem management policies. We also aimed to provide more insights on how large-scale scenario developments can be translated to the local level. In doing so, we emphasized specific local characteristics and used highly participatory methods focusing on novel elements, such as organizing back-to-back workshops, creating coherent scenarios across scales, using visual elements to present exploratory scenarios, and combining exploratory scenarios with normative backcasting using a World Cafe methodology. The outcome scenarios and management proposals are relevant for decision making and planning processes at local scale and at the same time, they are comparable to other assessment scenarios. This local participatory scenario process and tool for landscape planning is already having a policy impact thanks to the involvement of public administration technicians and policy makers. In the recently renewed strategic policy plan for sustainability of the county, this assessment is considered a high priority. Therefore, for the next steps of the assessment, detailed guidelines for ecosystem management policies are planned.

Phytoplankton blooms in the Urdaibai estuary during summer: Physico-chemical conditions and taxa involved

In the Urdaibai estuary, despite its small volume in relation to the tidal prism, phytoplankton grows massively in the upper and intermediate zones of the estuary during summer when rainfall is low to moderate. Data obtained in 23 sampling transects along the longitudinal axis of the estuary, undertaken in July 1993 and August 1994, showed three distinct zones in terms of the phytoplankton species composition: in the upper zone the phytoplankton assemblage was dominated by the diatoms Cyclotella spp., the dinoflagellate Glenodinium foliaceum, cryptophytes and euglenophytes; in the intermediate zone the diatom Chaetoceros ceratosporus, the dinoflagellates Peridinium quinquecorne and Prorocentrum minimum and cryptophytes were the most abundant; in the lower zone diatoms such as Leptocylindricus danicus and Skeletonema costatum together with the dinoflagellates Prorocentrum spp. were dominant. The distribution and abundance of these phytoplankton forms is discussed in relation to variations in salinity, water column stratification, nutrients and temperature, which in turn vary mainly as a function of meteorological conditions (i.e. rainfall, irradiance) and tidal amplitude. The longitudinal distribution of phytoplankton cells suggests that the diatoms Cyclotella spp. and Chaetoceros ceratosporus undergo a greater dispersion along the estuary during rain events than the flagellates, thus contributing to the transport of silica to the outer areas of the estuary.

Integrating stakeholders’ demands and scientific knowledge on ecosystem services in landscape planning

The conflict between conservation and timber production is shifting in regions such as Biscay (Basque Country, northern Spain) where planted forests are no longer profitable without public subsidies and environmentalist claim that public subsidies should be reoriented to the regeneration of natural forest. This paper develops an approach that integrates scientific knowledge and stakeholders’ demands to provide decision-making guidelines for the development of new landscape planning strategies while considering ecosystem services. First, a participatory process was conducted to develop a community vision for the region’s sustainable future considering the opportunities and constrains provided by the landscape and its ecosystems. In the participatory process forest management was considered an important driver for the region`s landscape development and forest multi-functionality was envisioned as a feasible attractive alternative. The participatory process identified a knowledge gap on the synergies and trade-offs between biodiversity and carbon storage and how these depend on different forest types. Second, to study the existing synergies and trade-offs between biodiversity and carbon storage and disentangle the identified knowledge gap, a GIS-based research was conducted based on spatially explicit indicators. Our spatial analysis results showed that natural forests’ contribution to biodiversity and carbon storage is higher than that of the plantations with exotic species in the region. The results from the spatial analysis converged with those from the participatory process in the suitability of promoting, where possible and appropriate, natural forest ecosystems restoration. This iterative learning and decision making process is already showing its effectiveness for decision making, with concrete examples of how the results obtained with the applied approach are being included in planning and decision-making processes.

Potential risk of harmful algae transport by ballast waters: The case of Bilbao Harbour

Ballast water exchange was measured for the first time in Bilbao Harbour, one of the most active of northern Spain. Between 1997 and 2006, 41,900,980.34 ballast water tn were loaded and 13,272,709 tn were discharged. Bilbao Harbour appears to be mainly a source of ballast water, 90% of which would be discharged in European harbours. We estimated that vessels carrying liquid and solid bulk have higher probabilities of exporting ballast water, whereas those with liquid bulk and containers are more likely to introduce it. From 30 potentially harmful phytoplankton species identified to date near harbour facilities, there would be a high risk of exporting at least Alexandrium minutum, Dinophysis sp., Heterosigma akashiwo, Karlodinium sp., Ostreopsis cf. siamensis, Pfiesteria-like and Prorocentrum minimum. Invasion risk by ballast water was tested by analyzing the response of six strains of H. akashiwo from different geographic areas to varying salinity. Results show that successful growth of foreign strains would be possible.

Photosynthesis and carbon metabolism by size-fractionated phytoplankton in the southern North Sea in early summer

Abstract Productivity and physiological parameters of three size fractions of phytoplankton were measured in the southern North Sea in June 1989, in the period after the major Phaeocystis blooms had occurred. The central region was characterized by low densities of a dimoflagellate-dominated plankton assemblages, but the German Bight had much higher phytoplankton biomass and productivity, which was due to increases in the numbers of 5 μm phytoplankton. The productivity of small nanoplankton and picoplankton was relatively constant throughout the region. The physiological conditions of the three phytoplankton size fractions were assessed by measuring the incorporation of14C labels into metabolic intermediates and by determining photosynthesis/irradiance curves. In 24 h incubations, most of the label in all size fractions was found in protein; however, there were differences between size fractions with more of the total label being in protein and less in low molecular weight metabolites for the picophytoplankton than for the 5 μm phytoplankton. Similarly, there were differences in photosynthetic parameters of the three size fractions, with values of both PmB and aB which were always lowest for 5 μm phytoplankton and highest for the picoplankton. There was good agreement between values of PmB and the synthesis ratio of protein to low molecular weight metabolites.