Social network analysis as a tool to inform anguillid eel conservation and management

Eel Management Plans demand European silver eel (Anguilla anguilla) escapement to the sea of at least 40% of that expected historically in the absence of human impacts. Landlocked lentic waterbodies, such as drinking water reservoirs, host substantial numbers of eel, which could represent a significant contribution to catchment-based conservation targets. To optimize netting strategies for eel management policies, information on their aggregation behaviour is currently needed but lacking. We performed a fine-scale acoustic tracking study to monitor the movements of 86 European eel in a UK reservoir. Social network sampling and sensitivity analyses were used to assess whether eel aggregate at scales relevant for current capture techniques. European eel were found to aggregate at spatial and temporal scales of 50 m and 2 days, respectively, which complements current capture methodologies and recommendations. Aggregations were not driven by fixed resources, indicating that other factors, such as sociality, may drive aggregation behaviour. Results also show that current netting practices could be optimized by increasing netting lengths from 50 to 80 m. In addition to aiding conservation and management protocols, these results provide an ecological foundation for exploring the role of social behaviour in this Critically Endangered species

Convexity deficit of benzenoids

In 2012, a family of benzenoids was introduced by Cruz, Gutman, and Rada, which they called convex benzenoids. In this paper we introduce the convexity deficit, a new topological index intended for benzenoids and, more generally, fusenes. This index measures by how much a given fusene departs from convexity. It is defined in terms of the boundary-edges code. In particular, convex benzenoids are exactly the benzenoids having convexity deficit equal to 0. Quasi-convex benzenoids form the family of non-convex benzenoids that are closest to convex, i.e., they have convexity deficit equal to 1. Finally, we investigate convexity deficit of several important families of benzenoids

Influences of angler subsidies on the trophic ecology of European barbel Barbus barbus

European barbel Barbus barbus is a recreationally important riverine fish that is widely introduced outside of its natural range. Contemporary angling practices for B. barbus involve the use of baits based on marine fishmeal (MF). MF is isotopically distinct from freshwater prey via highly enriched δ13C and thus its dietary influence on B. barbus can be tested via differences in fractionation factors (Δ13C). Correspondingly, stable isotope data from 11 riverine B. barbus populations tested how their trophic ecology varied across populations according to MF from angling. Δ13C of fish with macroinvertebrate prey resources varied within and between populations (range 0.90 to 10.13 ‰) and indicated that, within populations, up to 71 % of B. barbus had relatively high dietary contributions of MF. These contributions were significantly and positively related to fish length, with MF influences increasingly apparent as fish length increased. Population isotopic niche sizes increased as the dietary influence of MF in that population increased. These results indicated that whilst MF from angling can act as a strong trophic subsidy, its influence varies spatially and with fish length, with its use as a food resource by B. barbus generally involving dietary specializations of larger-bodied individuals

Multidisciplinary investigations of a karst reservoir for managed aquifer recharge applications on the island of Vis (Croatia)

Managed aquifer recharge (MAR) refers to a suite of methods by which excess surface water or non-conventional water is stored underground for subsequent recovery or environmental purposes. MAR solutions have been largely used in unconsolidated aquifers, while their application in karst aquifers is rare. This research presents the first results of a MAR viability study on the island of Vis, a small karstic island in the Adriatic Sea. Favorable geological and hydrogeological conditions enable the formation of karst aquifers, making the island autonomous in terms of water supply. The island's main aquifer, exploited in the Korita well field, is protected from seawater intrusion by several hydrogeological barriers. However, climate change and high seasonal pressures related to tourism pose a threat to the future availability of freshwater. Multidisciplinary field and laboratory investigations were carried out to detail the geological and hydrogeological setting of the island and its groundwater resource. Field analyses consisted of groundwater monitoring and sampling, geophysical investigations (i.e., electrical resistivity tomography), and structural measurements. Laboratory analyses included measurements of principal cations and anions and tritium activity. Despite low precipitation during the observation period (September 2019 - December 2020), the groundwater resource at the Korita site showed stable trends of physico-chemical parameters with a good storage potential and a long-term reserve. Geophysical investigations evidenced a relatively homogeneous sequence of the rock mass at a larger scale, while structural analyses indicated the occurrence of E-W karstified and open fractures that could represent a preferential flow path in the carbonate aquifer. A MAR solution for the Vis island was proposed combining an infiltration pond scheme with the direct injection of the accumulated waters into the aquifer using available wells. The potential water source could be represented by the runoff collected in an old artificial channel and the associated pond system in Korita

Changes in Edam type cheese during storage

Sir edamskog tipa sazrijevao je u standardnim uvjetima zapakovan u šaran foliju. Zreli sir čuvan je na temperaturi 10 i 20 °C. U intervalima od 10 ili 20 dana praćene su organoleptičke, mikrobiološke i kemijske promjene u siru. Ispitivanja su prekinuta u trenutku kada uzorci više nisu odgovarali za potrošnju. Utvrđeno je vrijeme kada nastaju pojedine faze kvarenja i procijenjen optimalan rok održivosti sira u navedenim uvjetima.Edam, type cheese was ripened in standard conditions packed in Saran foil. Ripe cheese was preserved at the temperature of 10 and 20 °C. Organoleptic, microbiological and chemical changes in cheese were observed in intervals of 10 and 20 days. Investigations were terminated when the samples were no longer suitable for consumption. The point when different phases in spoiling occur was determined. Optimal time of cheese preservation in specific conditions was estimated

On Words with the Zero Palindromic Defect

We study the set of finite words with zero palindromic defect, i.e., words rich in palindromes. This set is factorial, but not recurrent. We focus on description of pairs of rich words which cannot occur simultaneously as factors of a longer rich word