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Community Ecology
Authors: Á. Móréh, F. Jordán, A. Szilágyi, and I. Scheuring

There is increasing evidence that regime shifts occur at several scales in ecosystems (from the spatiotemporal alternation of two species to large-scale, ecosystem-level rearrangements). Yet, the theoretical background for understanding these changes is far from clear. Since fishing down in marine ecosystems is well-documented trend, and its top-down cascading effects in food webs have been richly documented, it is a current question whether overfishing, in general, can also influence regime shifts at lower levels. We model simple marine ecosystems by dynamical food webs and investigate the probability of regime shifts emerging among primary consumers. We considered cases where only one of the primary consumers is persistent in the stationary state. By perturbing the death rates in the food web, we studied the circumstances when the previously persistent primary producer is indirectly changed by the previously non-persistent one. Whether and how regime shifts (e.g., change in primary consumers) can occur depends on (1) food web topology (presence of top-predator and alternative producer), (2) the relative strength of perturbation of primary consumers’ death rates, and (3) the dynamical parameters of the recovering consumer. We found that overfishing, food web topology and dynamical parameters together determine the probability of regime shifts. Thus, integrative and complex models are needed in multispecies fisheries.

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57 129 138 Osberg, L. (1993): Fishing in Different Ponds: Job-Search Strategies and Job-Finding Success in Canada in the early 1990s. Journal of

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. (1992): The technology of seed production. In: Carp and Pond Fish Culture. Fishing News Books, pp. 23-55. Carp and Pond Fish Culture. 23 55

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Since the initiation of large-scale development in late 1970s, the Mahaweli River basin in Sri Lanka has experienced significant changes. However, no comprehensive study has been undertaken so far to evaluate the impacts of river regulation on associated ecosystems including floodplains in the downstream. The present study was aimed at identifying the impacts due to both river regulation and other anthropogenic activities on inland floodplain habitats (locally known as villus) located along the final stretch of the River Mahaweli before reaching the Indian Ocean. Four villus, Handapana (HAN), Bendiya (BEN), Karapola (KAR) and Gengala (GEN), were selected for the study. HAN and BEN can be considered as highly influenced (HI) by river regulation while KAR and GEN as less influenced (LI) due to their respective locations. Due to the absence of pre- regulation vegetation data, HI villus were compared with LI villus in order to explore any potential impacts of river regulation. Vegetation was enumerated using belt transect method. To find out other on-going anthropogenic impacts on these villu ecosystems, a survey was conducted using 100 individuals living in two villages located nearby. The results revealed some significant modification in the composition and the diversity of the vegetation, most possibly due to river regulation and other on-going anthropogenic activities. However, the most notable changes were recorded in the herbaceous layer. Some native aquatic herbaceous species have been completely absent over the period of two decades since the developmental activities begun, while some exotic invasive aquatic species (Eichhornia crassipes) dominated the herbaceous layer in HI villus threatening the survival of the remaining native species. Density and richness of lianas too diminished significantly in HI villus perhaps due to changes of micro-habitat conditions as a result of river regulation and also due to over-harvesting for commercial purposes. The results suggest that these ecosystems have been altered over the years due to culmination of factors including altered flow regimes following river regulation and some on-going human influences. The present study highlights the importance of regulating such human influences on villus including fishing and extracting cane and reed in order to protect these vulnerable ecosystems for future generations. The potential of these ecosystems to develop ecotourism has also been emphasized.

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Orvosi Hetilap
Authors: Alexandra Juhász, Ádám Dán, Béla Dénes, István Kucsera, József Danka, and Gábor Majoros

Absztrakt

Az állatokban sok mételyfaj él, amelyek lárvája a gazda bőrén keresztül fertőzi azt. Ezek közül az ember szempontjából a legfontosabbak az emlősök vérmételyei, mert belőlük kerülnek ki az embert fertőzni képes vérmételyek is. Több fajuk a trópusi országok lakóinak rettegett schistosomosisát okozza, míg más fajok behatolnak ugyan az ember bőrébe, de adulttá nem válnak a testében. A mérsékelt égövben főleg az utóbbi, bőrgyulladás formájában jelentkező infekció fordul elő. A mételylárvák eredete legtöbbször nem tisztázható, ezért általában sem orvosok, sem állatorvosok nem foglalkoznak a fertőzés forrásával. Szarvasokban élő mételyfajról bizonyítottuk be, hogy a régen „vízi rühösség”-nek nevezett bőrbántalmat csigákból kirajzó cercariák okozzák. A Duna egyik árterén endemikus Schistosoma turkestanicum okozta dermatitis ritkán kerül orvos szeme elé, pedig informális közlések alapján úgy tűnik, hogy rendszeresen előforduló tünet a métely élőhelyén lévő vizekben halászó vagy fürdőző embereken. Ráutaló kórelőzmény esetén indokolt a humán vérmétely-fertőzöttséghez hasonló szerológiai reakciót adó cercaria dermatitis eredetét kivizsgáltatni. Orv. Hetil., 2016, 157(40), 1579–1586.

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Pauly, D., V. Christensen, J. Dalsgaard, R. Froese and F. Torres. 1998. Fishing down marine food webs. Science 279:860-863. Fishing down marine food webs Science

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Ackman, R.G. (1980): Fish lipids. Part 1. -in: Connell, J.J. (Ed.): Advances in fish science and technology . Fishing News Books Ltd, Farnham, Surrey, pp. 86

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. 2006. Comparing trophic flows and fishing impacts of a NW Mediterranean ecosystem with coastal upwelling systems by means of standardized models and indicators. Ecol. Model. 198: 53–70. Tudela S

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. MINISTRY OF AGRICULTURE. ( 2015 ): Situacní a výhledová zpráva ryby (Situation and outlook report on fish. Czech Republic-Ministry of Agriculture, Department of State forest governance, hunting and fishing (November 2015)) . Prague, Czech Republic , pp

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Motivation in a Remote Fishing Event. Festival Management and Event Tourism , 5: 231–241. Raybould M. Participant Motivation in a Remote Fishing Event

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