This research examines the impact of the COVID-19 pandemic on marine litter pollution along the Israeli coast, which constitutes a terminal area in the Mediterranean Sea large-scale circulation. Surveys for litter were conducted on four beaches along the Israeli Mediterranean coast. Sampling was done pre-pandemic in June, September, and December of 2019; during the first year of the pandemic in March, June, September, and December of 2020; and during the second year of the pandemic in March 2021. The study revealed that during the first year of the pandemic, beach litter concentration was reduced by 47 +/- 27% on all beaches. The decrease in beach litter continued during the second year on most beaches (34 +/- 22% reduction) and was most observable for plastic products, which have a high potential to float and travel long distances. The decline in beach litter concentration in the Israeli beaches during the pandemic was statistically significant. The barcode analysis indicates the appearance of non-Israeli debris on the shores (22-81% pre-COVID-19 and 5-47% during-COVID-19), which supports the assumption that the reduction in marine litter pollution was affected by the decline in beach activity both locally and in other coastal neighboring countries. An additional effect of the pandemic was the appearance of single-use plastic masks and gloves in April 2020, influenced by the epidemic's regulations and restrictions. Despite the decline in beach marine litter concentration during COVID-19, plastic pollution is a high concern in this heavily populated coastal region. Our data set provides an indication for the potential of local and regional regulations to reduce further beach litter pollution and a baseline for continuous monitoring of these processes.

Sand beach nourishment (BN) is one of the commonest “soft solutions” for shore protection and restoration. Yet it may have ecological consequences. Can this practice enhance the introduction and dispersal of non-indigenous species (NIS)? There has been little research on the impacts of nourishment on NIS, especially in the southeastern Mediterranean, a region considered most affected by invading biota. However, so far only one study referred to the possible interaction between BN and the success of invading species. It reports increasing numbers and densities of the aggressive, omnivorous Indo-Pacific moon crab, Matuta victor (Fabricius, 1781) in Haifa Bay (northern Israel) between 2011 and 2017. This research suggests a possible role of anthropogenic disturbance in the outbreak of M. victor and blames the Israel Ministry of Environmental Protection for authorizing a (rather small scale) BN in Haifa Bay in 2011 as an alleged cause for this outbreak. Circumstantial indirect evidence is not sufficient to establish the role of nourishment in promoting the establishment and dispersal of NIS. There are plenty of examples of successful settlement and rapid and large-scale distribution of NIS (including another member of the genus Matuta), especially in the eastern Mediterranean, without any BN in the region. Furthermore, the location where the M. victor specimens were sampled was exposed to more prevailing and frequent anthropogenic marine stressors than BN, such as eutrophication, pollution, fishing activities and particularly port construction. To firmly establish an assumed role of nourishment in the invasion of NIS, assessments must be based on solid and orderly planned scientific research to be designed well before the beginning of any BN. It is suggested that direct communication between environmental regulators and scientists is crucial for improving both scientific research and environmental management policies.

Anthropogenically-induced oil spills release large amounts of organic pollutants into the marine environment. To date, little is known about the response of microbial populations (biomass, activity and diversity) to crude oil pollution in Low Nutrients Low Chlorophyll and warm systems. Here, we investigated the daily dynamics of phytoplankton and heterotrophic bacteria in response to an oil spill (500 um thick layer) in the coastal waters of the SE Mediterranean Sea (SEMS), using mesocosms during winter and summer. Crude oil addition caused a marked decrease in phytoplankton biomass (40-76%) and production rates (22-96%), whereas heterotmphic bacterial abundance and production increased (4-68% and 17-165%, respectively). Concurrently, amplicon sequencing of the 16S rRNA gene revealed that oil-degrading bacteria became abundant 48-96 h post-oil addition, while the cosmopolitan Synechococcus and SAR11 lineages were significantly reduced (by 78-98% and 59-98%, respectively). Fertilization with inorganic nutrients (NO3 and PO4) reduced the deleterious effects of the oil, resulting in a less distinct reduction in phytoplankton biomass/abundance. Our results highlight the potential of intrinsic microbial communities to degrade oil-derived pollutants in oligotrophic coastal waters.

The Indo-Pacific oyster Chama pacifica Broderip, 1835 (Mollusca, Bivalvia, Chamidae) is rarely found in the Northern Red Sea reefs of Eilat (Gulf of Aqaba), where it is outnumbered by its indigenous congener, Chama savignyi Lamy, 1921. The influx of Eritrean biota from the Red Sea into the Mediterranean Sea via the Suez Canal has led to the formation of massive Chama oyster beds along the Eastern Mediterranean shore. However, unlike the Northern Red Sea, the Eastern Mediterranean Chama beds are dominated by C. pacifica oysters, whereas C. savignyi is absent from this region. In an attempt to understand this difference in their respective distribution, the reproductive biology of both species was compared. Histological analysis of the male and female gonads, monitored monthly from March 2009 to August 2010 in both regions, revealed a similar reproductive cycle, comprising six stages: onset of gametogenesis, advanced gametogenesis, ripe, ready to spawn, spent and sexual rest. Female gonads demonstrated an additional, seventh stage restoration, coinciding with inferred spawning of ripe gametes. Both species were found to be dioecious spawners, with a single, annual, temperature-dependent inferred spawning period. Chama pacifica was found to reproduce efficiently in maximal Mediterranean seawater temperatures not experienced by the Northern Red Sea Chama populations. This study demonstrates the high invasive potential of an oyster species despite its rarity in its source region.

Gill bacterial communities of Chama pacifica, an Indo-Pacific invasive oyster to the eastern Mediterranean Sea, were compared with those of Chama savignyi, its northern Red Sea congeneric species. Summer and winter bacterial populations were characterized and compared using 16S rDNA clone libraries, and seasonal population dynamics were monitored by automated ribosomal intergenic spacer analysis (ARISA). Clone libraries revealed a specific clade of bacteria, closely related to marine endosymbionts from the Indo-Pacific, found in both ecosystems, of which one taxon was conserved in oysters from both sites. This taxon was dominant in summer libraries and was weakly present in winter ones, where other members of this group were dominant. ARISA results revealed significant seasonal variation in bacterial populations of Mediterranean Sea oysters, as opposed to Red Sea ones that were stable throughout the year. We suggest that this conserved association between bacteria and oyster reflects either a symbiosis between the oyster host and some of its bacteria, a co-invasion of both parties, or both.

Many cnidarians form an obligatory mutualism with photosynthetic algae (zooxanthellae) of the genus Symbiodinium. Break-down of this symbiosis leads to bleaching, and often death, of the host. Coral hosts may survive such break-down of symbiosis by exchanging their algal types, provided they can host multiple symbiont types. The soft coral Litophyton crosslandi (Octocorallia, family Nephtheidae) transmits its symbionts vertically to its sexual progeny during oogenesis. This has been considered a "closed symbiosis", in which the host retains the same single zooxanthellae type throughout its entire life span. In this work we examined the possible entry of heterologous zooxanthellae into primary polyps of a vertically transmitting host. Primary polyps were challenged with DAPI-stained heterologous clade C zooxanthellae, allowing their visualization and distinction from the homologous clade A ones. DAPI-stained zooxanthellae were found in the epidermis. and in some cases even in the gasterodermis, of the polyps. The entry of heterologous symbionts and their survival inside host tissue suggests that the latter may indeed possess the ability to host different algae. These findings also suggest an entry pathway via the epidermis that, prior to this study, has not been described for vertical transmitters. These results further contribute to the understanding of coral ability to cope with stress-induced bleaching.

To explore the scope and significance of alternate promoter usage and its putative inter-relationship to alternative splicing, we searched expression sequence tags for the 5' region of acetylcholinesterase ( ACHE) genes. Three and five novel first exons were identified in human and mouse ACHE genes, respectively. Reverse transcription-PCR and in situ hybridization validated most of the predicted transcripts, and sequence analyses of the corresponding genomic DNA regions suggest evolutionarily conserved promoters for each of the novel exons identified. Distinct tissue specificity and stress-related expression patterns of these exons predict combinatorial complexity with known 3' alternative AChE mRNA transcripts. Unexpectedly one of the 5' exons encodes an extended N terminus in-frame with the known AChE sequence, extending the increased complexity to the protein level. The resultant membrane variant(s), designated N-AChE, is developmentally regulated in human brain neurons and blood mononuclear cells. Alternative promoter usage combined with alternative splicing may thus lead to stress-dependent combinatorial complexity of AChE mRNA transcripts and their protein products.

Science education nowadays faces manifold challenges. Adequate scientific knowledge is crucial for understanding the complex environment and reality within which we live; however, there is an alarming decline in number of students choosing science subjects. Motivational aspects are key factors for this decline, resulting from both inadequate pedagogical approaches to science teaching (Novak, 1998) and from students' perception of contents as uninteresting and tedious (Osborne & Hennessy, 2003). ICT is broadly used in science education for handling numerical data, however constructing conceptual interpretations of system's behavior (e.g. White & Frederiksen, 1998) requires ICT software supporting learners in actively dealing with the theoretical concepts such as visualization and diagrammatic techniques, creation of models and concept prediction and explanation (Niedderer et al., 2002). However, such techniques are unavailable or too complex to use, and therefore are seldom part of prescribed science activities (Osborne & Hennessy, 2003). The DynaLearn project aims to develop and implement effective educational tools for learning about complex systems using a qualitative modeling approach (Bredeweg et al., 2006; Bredeweg & Struss, 2003). This approach regards a model as an abstraction that captures ordinal knowledge and predicts the set of qualitatively possible behaviors of the system, given a qualitative description of its structure and initial state. Dynalearn project is funded by the European Union's 7 th framework programme and carried by a consortium of eight participant partners. The main components of the DynaLearn Environment are Conceptual Modeling (CM), Semantic Technology (ST) and Virtual Characters (VC). The CM component is used for learners to articulate, analyze and communicate ideas, and thereby construct their conceptual knowledge (Figure 1). The VC component is used to generate meaningful feedback of various types, and make the interaction engaging and motivating. The ST component is used to deliver semantically appropriate feedback. The research was conducted during 2009/2010 academic semester, as part of the Marine Biology course at the Faculty of Life Sciences in Tel Aviv University. A group of 10 undergraduate students attended a 7 weeks seminar using DynaLearn environment with the purpose of constructing a model related to the course syllabus. In the evaluation process we analyzed the students' active construction of their models, their ability to interpret given states of a model,