Positive association between understory species richness and a dominant shrub species (Corylus avellana) in a boreonemoral spruce forest

Old growth stands of boreonemoral spruce (Picea abies) forests frequently have a shrub layer dominated by hazel (Corylus avellana) – a species which is generally excluded in intensively managed forests due to clearcutting activities. We sampled understory species composition, richness and biomass, as well as environmental variables beneath these two species and also within forest ‘gaps’ in order to determine the effect of overstory species on understory vegetation. Species richness and biomass of herbaceous plants was significantly greater under Corylus compared with plots under Picea and in forest gaps. Indicator species analysis found that many species were significantly associated with Corylus. We found 45% of the total species found under woody plants occurred exclusively under Corylus. Light availability in spring and summer was higher in gaps than under forest cover but no difference was found between plots under Corylus and Picea. Hence, reductions in light availability cannot explain the differences in species composition. However, Ellenberg indicator values showed that more light demanding species were found under Corylus compared to Picea, but most light demanding species were found in gaps. The litter layer under Picea was three times thicker than under Corylus and this may be an important mechanism determining differences in understory composition and richness between the woody species. The presence of Corylus is an important factor enhancing local diversity and small-scale species variation within coniferous stands. Hence, management should maintain areas of Corylus shrubs to maintain understory species diversity in boreal forests.     

Effect of phosphite fertilization on growth,yield and fruit composition of strawberries

Traditionally, phosphates (Pi, salts of phosphoric acid, H₃PO₄) have been used for plant fertilization, and phosphites (Phi, salts of phosphorous acid, H₃PO₃) have been used as fungicides. Nowadays several Phi fertilizers are available in the EU market despite the fact that in research trials Phi has often had a negative influence on plant growth. The objective of this study was to elucidate the effect of a Phi fertilizer on plant growth, yield and fruit composition of strawberries (Fragaria × ananassa Duch.). Experiments were carried out with ‘Polka’ frigo plants in South Estonia in 2005 and 2006. The number of leaves per plant, total and marketable yields, fruit size, fruit ascorbic acid content (AAC), soluble solids content (SSC), titratable acidity (TA), anthocyanins (ACY) and total antioxidant activity (TAA) were recorded.     

Incidence of antibiotic resistant fecal coliforms in the coastal waters of Kuwait

In order to assess the water quality of Kuwait's coastal waters, antibiotic-resistant fecal coliforms were monitored at eleven sites along the coastal area. The data showed that different levels of antibiotic-resistant bacteria were distributed along the coast. Many antibiotic-resistant species of fecal origin were isolated from seawater and 93% of these isolates were found to be resistant to more than one antibiotic. Laboratory experiments indicated that these resistant strains could survive longer than sensitive strains in seawater and could transfer this resistant pattern to another species with high frequency.     

Glutamate dehydrogenase and glutamine synthetase activity in the digestive tract in lambs in relation to age]

Developmental dynamics was investigated in the activity of glutamate dehydrogenase (GDH, E.C. 1.4.1.2.-4) and glutamine synthetase (GS, E.C. 6.3.1.2) in different parts of the digestive tract of lambs, in dependence on the age from 10 to 90 days; the goal of these investigations was to elucidate in greater detail the role of the above enzymes in nitrogen metabolism. The activity of GDH, and of the coenzymes NADH and NADPH, was followed in the digesta because simple organisms (bacteria, fungi, plants) have two glutamate dehydrogenases: they differ from each other by coenzyme specificity, unlike GDH from animal sources which can utilize both NADH coenzyme and NADPH coenzyme (Fahien et al., 1965; Frieden, 1964). The following activities of GDH and GS were found out in trials with lambs at the age of 10, 20, 30, 40 and 90 days, as to the different parts of digestive tract: in the tissues of rumen, omasum, reticulum, spleen, duodenum, jejunum, ileum, int. caecum and colon the activity of GDH (NADH) varied from 0.031 to 0.305 nkat/mg dry matter, in the digesta from 0 to 2.92 nkat/mg dry matter. An investigation of GDH (NADH, NADPH) dynamics in the digesta of lambs showed the relatively high activity of GDH (NADH) in the digesta of colon at the age of 10 days and that of GDH (NADPH) in the digesta of int. caecum. The activity of GDH (NADH) was also found to be high in the digesta of int. caecum at the age of 20 days. In that period the activity of GDH (NADH, NADPH) in the digesta of rumen, omasum and reticulum was zero.(ABSTRACT TRUNCATED AT 250 WORDS)     

The implications of a feelings-based approach to fish welfare: a reply to Arlinghaus et al.

The welfare of fish is a topic of increasing debate touching on a number of complex scientific and ethical issues and constructive dialogue between groups with differing approaches to the topic requires mutual understanding from both perspectives. In a recent review aimed at stimulating debate on this topic, Arlinghaus et al. (2007) explore the question of fish welfare in the particular context of recreational angling, by means of a critique of a review of fish welfare in general written by ourselves ( Huntingford et al. 2006 ). We entirely agree with the desirability of debate on this topic and recognize a number of valuable qualities in the commentary by Arlinghaus et al. However, we argue that the critique has some serious flaws. In the first place, by rejecting a feelings‐based approach to welfare, it fails to address the aspect of welfare that is at the heart of much legitimate public concern. Secondly, while advocating an objective, scientific approach to fish welfare, Arlinghaus et al. fail to present their own agenda (that recreational angling is morally acceptable) in a transparent way. Thirdly, they seriously misrepresent the position taken in Huntingford et al. (2006) on a number of important issues. In this reply, we address these points and then discuss briefly the areas of agreement and constructive disagreement between the two reviews.     

Early morphological predictors of maturity in one-sea-winter Atlantic salmon

Early separation of maturing from immature fish would be very valuable in Atlantic salmon (Salmo salar) culture. Possible morphometric predictors of maturation in one sea-winter Atlantic salmon were investigated from measurements of body weight, length and depth and adipose fin length undertaken at 14 day intervals from May until August in a population of 80 individually tagged fish, 61 (male and female) of which were subsequently found to be maturing (i.e. grilse). Stepwise discriminant analysis revealed that a combination of forklength and condition factor proved to be the strongest and most consistent predictor of maturation (over 88% accurate) until August. In August when maturing fish could be easily distinguished by shape and colour, forklength and condition factor no longer had any discriminatory power, but body depth at the anal and dorsal fins were good predictors. A second trial was performed on a separate stock of fish for which the same predictors proved robust. The discriminant functions derived from one stock of fish did not, however, produce the same discriminatory power when applied to the other stock. Hence there does not appear to be a simple mathematical means for the general discrimination of maturing and immature salmon. However the morphological predictors described above could be used for visual discrimination when ‘grilse grading’.     

Lévy walks evolve through interaction between movement and environmental complexity

Ecological theory predicts that animal movement is shaped by its efficiency of resource acquisition. Focusing solely on efficiency, however, ignores the fact that animal activity can affect resource availability and distribution. Here, we show that feedback between individual behavior and environmental complexity can explain movement strategies in mussels. Specifically, experiments show that mussels use a Lévy walk during the formation of spatially patterned beds, and models reveal that this Lévy movement accelerates pattern formation. The emergent patterning in mussel beds, in turn, improves individual fitness. These results suggest that Lévy walks evolved as a result of the selective advantage conferred by autonomously generated, emergent spatial patterns in mussel beds. Our results emphasize that an interaction between individual selection and habitat complexity shapes animal movement in natural systems.     

Impacts of artificial drainage on amphibian breeding sites in hemiboreal forests

Artificial drainage is widely used to increase timber production and improve its quality in northern boreal and temperate forests, but its impact on biodiversity remains largely unexplored. Amphibians are particularly dependent on forest wetland qualities to complete their complex life cycles. We explored the supply of water bodies, their occupancy by amphibians, and persistence during the larval period comparatively in drained and natural forest plots in two years in Estonia. The water bodies in drained plots were more abundant but less diverse and of generally lower quality than in natural plots; however, the drainage ditches were favoured by newts. In the dry spring of 2009, water bodies were used more frequently in natural than in drained plots, while in the typical spring of 2010, several natural depressions appeared in drained plots and the frequency of use of water bodies did not differ between natural and drained plots. However, most natural depressions used for breeding in drained plots dried out before tadpole metamorphosis; such drying was not observed in natural plots. Thus, by profoundly changing natural hydrology, intensive large-scale forest drainage reduces the variety of water bodies and the quantity and quality of amphibian breeding sites. Moreover, we suspect that, at least in some years, temporary water bodies in drained areas function as ecological traps for amphibians. We suggest that, where possible, intact wet-forest areas with remaining natural hydrology should stay undrained. In areas already drained, breeding sites for amphibians can be provided by creating depression-like enlargements to some ditches.     

Experimental evidence for spatial self-organization and its emergent effects in mussel bed ecosystems

Spatial self-organization is the main theoretical explanation for the global occurrence of regular or otherwise coherent spatial patterns in ecosystems. Using mussel beds as a model ecosystem, we provide an experimental demonstration of spatial self-organization. Under homogeneous laboratory conditions, mussels developed regular patterns, similar to those in the field. An individual-based model derived from our experiments showed that interactions between individuals explained the observed patterns. Furthermore, a field study showed that pattern formation affected ecosystem-level processes in terms of improved growth and resistance to wave action. Our results imply that spatial self-organization is an important determinant of the structure and functioning of ecosystems, and it needs to be considered in their conservation.     

Self-organized patchiness and catastrophic shifts in ecosystems

Unexpected sudden catastrophic shifts may occur in ecosystems, with concomitant losses or gains of ecological and economic resources. Such shifts have been theoretically attributed to positive feedback and bistability of ecosystem states. However, verifications and predictive power with respect to catastrophic responses to a changing environment are lacking for spatially extensive ecosystems. This situation impedes management and recovery strategies for such ecosystems. Here, we review recent studies on various ecosystems that link self-organized patchiness to catastrophic shifts between ecosystem states.