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Galil B.S.,Israel Oceanographic And Limnological Research
Integrative Zoology | Year: 2012

Over 660 alien marine multicellular species have been recorded in the Mediterranean Sea, with many establishing viable populations and subsequently dispersing from their points of entry. A brief overview is presented of the current state of knowledge of bioinvasions in the Mediterranean Sea, with particular attention paid to gelatinous invasive species. A database of alien species records was used to characterize their identity, pattern of expansion and native region, and to discuss the relative importance of different taxa and vectors in the various regions of the sea. The temporal and spatial spread of 4 alien scyphozoans and 2 alien ctenophores is outlined. Although thermophilic species constitute the majority of Mediterranean aliens, Erythrean aliens are predominant in the east, with shipping and mariculture being mainly responsible for introductions in the northwest. The propagule pressure driving the Erythrean invasion is powerful in the establishment and spread of alien species in the eastern Mediterranean. The implications of the enlargement of the Suez Canal, reflecting patterns in global trade and economy, are briefly discussed. Finally, as alien species inventories play a pivotal role in informing regional policy and management decisions and identifying resource priorities, the scientific community is called upon to pay particular attention to their accuracy and veracity. © 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS. Source

Rinkevich B.,Israel Oceanographic And Limnological Research
Advances in Experimental Medicine and Biology | Year: 2012

Cnidarian taxa, currently of the most morphologically simplest extant metazoans, exhibit many salient properties of innate immunity that are shared by most Animalia. One hallmark constituent of immunity exhibit by most cnidarians is histocompatibility, marked by wide spectrum of allogeneic and xenogeneic effector arms, progressing into tissue fusions oRinflammatory rejections. Scientific propensity on cnidarians immunity, while discussing historecognition as the ground for immunity in these organisms, concentrates on host-parasitic and disease oriented studies, or focuses on genome approaches that search for gene homologies with the vertebrates. Above tendency for mixing up between historecognition and host-parasitic/disease, highlights a serious obstacle for the progress in our understanding of cnidarian immunobiology. Here I critically overview four 'forgotten' cnidarian immune features, namely, specificity, immunological memory, allogeneic maturation and natural chimerism, presenting insights into perspectives that are prerequisite for any discussion on cnidarian evolution. It is evident that cnidarian historecognition embraces elements that the traditional field of vertebrate immunology has never encountered (i.e., variety of cytotoxic outcomes, different types of effector mechanisms, chimerism, etc.). Also, cnidarian immune features dictating that different individuals within the same species seem to respond differently to the same immunological challenge, is far from that recorded in the vertebrates' adaptive immunity. While above features may be connected to host-parasitic and disease phenomena and effector arms, they clearly attest to their unique critical roles in shaping cnidarians historecognition, calling for improved distinction between historecognition and host-response/ disease disciplines. The research on cnidarians immunity still suffers from the lack of accepted synthesis of what historecognition is or does. Mounting of an immune response against conspecifics or xenogeneic organisms should therefore be clearly demarcated from other paths of immunity, till cnidarian innate immunity as a whole is expounded. © 2012 Landes Bioscience and Springer Science+Business Media. Source

Nishri A.,Israel Oceanographic And Limnological Research
Air, Soil and Water Research | Year: 2011

During the 1950s, the shallow Lake Hula and its adjacent marshes, located in the watershed of Lake Kinneret (LK), were drained in order to increase arable land. The drainage resulted in increasing loads of nutrients in the Jordan River and in oxidative degradation of the underlying peat, followed by Aeolian (mostly) and riverine transport to LK. Peat had been accumulating in LK bed sediments since the 1950s, with peak deposits recorded in the mid-1970s. The routine monitoring of Norg and Corg, associated with the peat, in the watershed streams and in LK water (initiated in 1970) also showed the highest levels in the mid-1970s. During the 1980s, a succession of dense natural vegetation inhibited soil surface erosion and a decline in Aeolian transport of peat to LK was recorded. Inversed temporal patterns appear for oxygen and pH, and this is suggested to result from the dependence of these parameters on the magnitude of respiratory process, induced by peat availability. During the 1970s allochthonous peat resources supported about half of the zooplankton activity in LK and therefore the decline in peat availability during the 1980s was accompanied by a two-fold decline in zooplankton biomass. The subsequent lessening of grazing pressure together with the elevated inflows of bio-available P resulted in a significant rise in LK phytoplankton biomass. The 1980s decline in Norg associated with the peat led to lower N/P ratios in the external sources of nutrients to LK. These conditions may have favored the appearance of N2 fixing cyanobacteria noted in the lake since 1994. © the author(s), publisher and licensee Libertas Academica Ltd. Source

Bar-Zeev E.,Yale University | Rahav E.,Israel Oceanographic And Limnological Research
Frontiers in Microbiology | Year: 2015

This study explores the role of transparent exopolymer particles (TEP) as an additional carbon source for heterotrophic microbial activity in the eutrophic Qishon estuary. From the coastal station and upstream the estuary; TEP concentrations, β-glucosidase activity, bacterial production and abundance have gradually increased. TEP were often found as bio-aggregates, scaffolding algae, detritus matter and bacteria that likely formed "hotspots" for enhance microbial activity. To further demonstrate the link between TEP and heterotrophic bacterial activity, confined incubations with ambient and polysaccharide-enriched estuary water were carried out. Following polysaccharide addition, elevated (~50%) β-glucosidase activity rates were observed, leading to TEP hydrolysis. This newly formed bioavailable carbon resulted in significantly higher growth rates, with up to a 5-fold increase in heterotrophic bacterial biomass, comprising mostly high nucleic acid content bacteria. Taking together the findings from this research, we conclude that even in highly eutrophic environments heterotrophic bacteria may still be carbon limited. Further, TEP as a polysaccharide matrix can act as a metabolic surrogate, adding fresh bioavailable carbon through tight associations with bacteria in eutrophic ecosystems such as the Qishon estuary. © 2015 Bar-Zeev and Rahav. Source

Neori A.,Israel Oceanographic And Limnological Research
Journal of Applied Phycology | Year: 2011

Freshwater fish culture is generally considered the largest sector in world aquaculture. Several of the leading species consume "green water" plankton. This plankton-mostly microalgae (phytoplankton) and also bacteria, protozoa and zooplankton-grows in man-made fertilized water impoundments. The quantity of "green water" microalgae consumed by fish and shrimp is estimated here at a quarter billion ton fresh weight a year, about three and a half times as much as the entire recognized aquaculture. This estimate is based on the quantities of the microalgae consumed and the efficiencies of their use for growth by the main species in aquaculture. The cost of producing "green water" microalgae by the aquaculturists-mostly in SE Asia-is low. The populations in "green water" are biologically managed by the cultured fish themselves. The fish with their different feeding habits help "manage" the composition of the plankton and the overall water quality as they grow. The aquaculturists further manage "green water" through simple means, including water exchange and fertilization. Cost is remunerated partially by the income from sales of the fish and partially by bio mitigation services that "green water" polyculture ponds provide the aquaculturists in treating farm and household waste. A comprehension of the scale and importance of the microalgae sector to world aquaculture should lead to more research to improve understanding of algal population dynamics, growth factors, and efficiency of food chains. The consequent improved control of the plankton's interaction with fish and shrimp production in "green water" will undoubtedly contribute much to the expansion in production of seafood. © 2010 Springer Science+Business Media B.V. Source

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