Distribution and ecology of calanoid species in relation to morphometric and chemical characteristics of lakes and ponds of the Northern Apennines (Italy)

In 1999 a limnological campaign was carried out in 89 water bodies located in 8 valleys of the Northern Apennines (provinces of Genua, Piacenza, Parma and Reggio Emilia) at an altitude between 877 and 1772 m a.s.l. This survey took into account permanent lakes, but also temporary and ephemeral water bodies which had been scarcely considered in hydrobiological studies previously carried out in this area. Most of the biotopes were visited seasonally during the ice-free period (May - November). The aim of this research was to define the relationships between morphometric features, lithology, hydroperiod and chemical characteristics of the biotopes and the distribution of the three species of calanoid copepods reported in the Northern Apennines, i.e. Mixodiaptomus kupelwieseri, M. tatricus and Eudiaptomus intermedius. The two most common species, M. kupelwieseri and E. intermedius, show an overlap in their altitudinal distribution. However, the former species widely occurs in very shallow, temporary or ephemeral water bodies and the latter clearly prefers permanent, relatively deep waters. Also the water inonic concentration influences the distribution of these two diaptomids, while concentrations of dissolved inorganic nutrients seem to have a negligible effect. Mixodiaptomus tatricus was found only in two shallow ponds beyond 1700 m a.s.l. Co-occurrence of E. intermedius and M. kupelwieseri has been observed only in a pond, but the two species are not found at the same time. The proportion of subitaneous and resting eggs laid in different seasons was analysed in populations of E. intermedius. The voltinism of this species varies according to the duration of the filling period and the productivity of the water bodies. The persistence of diaptomids in the study area has been evaluated through the comparison with distributional data available from the 1950s for most of the permanent lakes and some temporary habitats. Populations appear to be stable over time also in scarcely predictable environments as temporary pools, although in some cases calanoids have disappeared from biotopes severely affected by anthropogenic impacts

Effects of tributary size on the resource supply and physical habitat at tributary junctions along two mainstem rivers

Tributary junctions are regarded as ecologically important due to unique habitat present; however, there is limited understanding of the drivers of habitat attributes at these locations. Using six sites across two mainstem rivers, we tested whether tributary size relative to main stem governs the strength and direction of response of substrate size, stream temperature, and nutrient and coarse particulate organic matter (CPOM) concentration. We found that only phosphorus and CPOM concentration showed a significant relationship with relative tributary size. Small tributaries contributed high concentrations, whereas concentrations in larger tributaries resembled the main stem. Often, tributary exports were enough to increase the resource concentration in the main stem by 40%. Substrate coarsened by ∼60% downstream of tributaries. Temperature asynchrony was observed, where tributaries contributed water between 2.8 °C cooler to 1.9 °C warmer than the main stem within one diel period. Our results highlight the importance of small tributaries for whole network functioning. However, large spatiotemporal variability revealed how habitat attributes are highly context-dependent in these locations and may be difficult to predict in both scientific and management settings.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Feedback brake distribution control for minimum pitch

The distribution of brake forces between front and rear axles of a vehicle is typically specified such that the same level of brake force coefficient is imposed at both front and rear wheels. This condition is known as ‘ideal’ distribution and it is required to deliver the maximum vehicle deceleration and minimum braking distance. For subcritical braking conditions, the deceleration demand may be delivered by different distributions between front and rear brak- ing forces. In this research we show how to obtain the optimal distribution which minimises the pitch angle of a vehicle and hence enhances driver subjective feel during braking. A vehi- cle model including suspension geometry features is adopted. The problem of the minimum pitch brake distribution for a varying deceleration level demand is solved by means of a model predictive control technique. To address the problem of the undesirable pitch rebound caused by a full-stop of the vehicle, a second controller is designed and implemented independently from the braking distribution in use. An extended Kalman filter is designed for state esti- mation and implemented in a high fidelity environment together with the model predictive control strategy. The proposed solution is compared with the reference ‘ideal’ distribution as well as another previous feed-forward solution

Factors influencing the seasonal phenology and composition of zooplankton communities in mountain temporary pools

Abstract In 2001 nine temporary pools of the northern Apennines (Italy) were visited on 13 occasions during the ice-free season (May to October). The aims of this research were to define the relationships between hydroperiod and other environmental variables and the Zooplankton. In total, 49 zooplankton taxa were identified: 36 rotifers, 5 cladocerans, 6 copepods and 2 anostracans. Our results indicate that hydroperiod is a major determinant affecting zooplankton species richness. The highest number of taxa was found in the pond having the longest duration. Distinctive species assemblages were observed in different habitat types: pools with the shortest hydroperiod were characterised by organisms with brief life cycles (e.g. rotifers) and/or typical of temporary habitat (e.g. anostracans). Of the physical and chemical characteristics, pH and chlorophyll-a appeared to have the largest influence on zooplankton distribution in the studied pools

Physical factors and dissolved reactive silica affect phytoplankton community structure and dynamics in a lowland eutrophic river (Po river, Italy)

We tested the hypothesis that species composition and persistence of phytoplankton communities in nutrient rich lowland rivers depends mainly on physical factors. The study aimed to analyse the effects of water discharge, temperature and chemistry on phytoplankton dynamic and species composition in the lowland reach of the eutrophic Po river (Italy). Both taxonomical and morpho-functional methods were used. True planktonic and tychoplanktic (i.e. detached taxa of benthic origin that remain in suspension) species were found, among which only a few taxa and functional groups prevailed. Diatoms were the most abundant, with a clear dominance of species either sensitive to the onset of water stratification or well adapted to turbid waters. Phytoplankton abundance, biomass and chlorophyll-a followed similar trends, attaining the highest values in summer, at low discharge rates. Correlation and multivariate analysis revealed that the development of a stable phytoplankton community was mainly controlled by water discharge rates. Namely, changes in water flow rates induced major variations in the community structure. The seasonal succession of phytoplankton assemblages was also related to water temperature and dissolved reactive silica availability to some extent overlapping flow effects

Trophic state and seasonal dynamics of phytoplankton communities in two sand-pit lakes at different succesional stages

The seasonal and inter-annual dynamics of phytoplankton in two Italian sand-pit lakes have been analysed over three years (2004-2006). The studied lakes, Ca' Morta (CM) and Ca' Stanga (CS), have a common origin and are contiguous, but are of different ages and have been managed in different ways. CM was created in 2002 and was still being dredged during the study period while sand quarrying in CS began in 1998 and ended at the beginning of the study period These conditions were thought to be of particular interest in assessing the influence of dredging activities on algal assemblages. Physical and chemical water parameters were also analysed to characterise the two lakes and investigate the effects of hydro-chemical features on phytoplankton. CS was stratified from April to October each year during the study period, while CM showed weaker thermal stratification. Conductivity, dissolved nitrate and dissolved reactive silica concentrations were greater in CM than in CS. The mixing depth/euphotic depth ratio was also higher in CM, probably because of water column mixing induced by hydraulic dredging. Overall. 185 phytoplankton taxa were found, of which ca 50% were present in both lakes. No significant diffrences in species richness were observed between lakes, but the decreasing trend of Simpson index values measured in CS showed a reduction in biodiversity after the excavation phose. Phytoplankton biomass was higher in CS than in CM, the latter being oligo-mesotrophic and the former mesotrophic. Diatoms and dinoflagellates were the dominant taxa in both lakes. The main differences in phytoplankton assemblages were related to the persistence of chryptophytes and chlorophytes in CM. Multivariate analyses support the hypothesis that different thermal patterns induced by dredging activities, along with certain physico-chemical parameters of the water, were the major factors shaping phytoplankton communities