In situ experiments on the effect of low pH on the ultrastructure of the seagrasses Cymodocea nodosa and Posidonia oceanica

The present study investigates the impacts of low pH on the cell structure of the seagrasses Posidonia oceanica (L.) Delile and Cymodocea nodosa (Ucria) Ascherson. The study was applied with in situ experiments at the Castello Aragonese of Ischia (Naples, Italy), where shallow submarine vents, lowering the pH, can be used as natural laboratories. Shoots of the seagrasses were transferred from the control area (pH 8.1) to the two venting areas (pH 7.8 and 6.8) for different times. Epidermal cells of young leaves were examined using transmission electron microscopy (TEM) and tubulin immunofluorescence. After one week at pH 7.8, the cell structure of Posidonia oceanica was normal, while in Cymodocea nodosa microtubule (MT) network and cell structure were affected. In addition, in C. nodosa, ultrastructural analysis revealed a gradual degradation of the nuclei, a disorganization of the chloroplasts, and an increase in the number of mitochondria and dictyosomes. The exposure of both plants for 3 weeks at pH 6.8 resulted in the aggregation and finally in the dilation of the endoplasmic reticulum (ER) membranes. Tubulin immunofluorescence revealed that after three weeks, the MT cytoskeleton of both plants was severely affected. All these alterations can be considered as indications of an apoptotic like programmed cell death (AL-PCD) which may be executed in order to regulate stress response.

Nesting activity of the Loggerhead sea turtle, Caretta caretta, in Calabria: 2016-2020 reproductive seasons

The nesting activity of the loggerhead turtle along the coast of Calabria during five reproductive seasons (2016-2020) is presented. From May to August, survey methods were conducted using traditional observations on foot and utilizing additional innovative technologies, including electric fat bikes and drones. Monitoring was intensively focused on a key nesting area of approximately 40 km located on the southernmost Ionian coast of Reggio Calabria, and, for only the 2020 season, the area was extended an additional 40 km northeast. In the five nesting seasons, 419 female emergences were recorded, 192 of which were classified as nests. Overall, 65.1% (n = 125) of nests were found along the area regularly monitored in all nesting seasons. The maximum nesting activity was observed during July, and the mean nesting success was 45.8%. The average number of eggs for all seasons was 92.2 (n = 163; S.D.: ± 21.1; range: 39-160). The mean hatching and emergence success rates were 70.8% and 62.5%, respectively. The mean incubation period was 49 days (n = 122; S.D.: ± 5.4; range: 42-82). Considering previous data from the same area, our study shows an actual increase in nesting activity, probably due to the implementation of an effective monitoring method that includes the use of new technologies, which made it possible to expand the regularly monitored area, and a greater awareness campaign in recent years. Regarding the reproductive parameters, our data is similar to that reported for other Mediterranean nesting grounds.

The last fortress fell: mass mortality of Pinna nobilis in the Sea of Marmara

A spring 2021 cruise to the south Marmara Islands revealed a mass mortality event of Pinna nobilis, which were reported to be healthy just seven months ago. The cause of death might be associated with the epidemic infection or a catastrophic mucilage event seen after November 2020 in the Sea of Marmara. A total of 191 Pinna nobilis individuals were found at seven stations out of 10, of which 88% were dead. In the present study, the population density (dead and alive individuals) of P. nobilis was found to be between 0.3 ind.100 m-2 and 12 ind.100 m-2 in the area. A total of three live and four dead juvenile individuals were observed in the area, indicating low recent recruitment. The highest number of dead Pinna nobilis individuals (92 specimens) was encountered in shallow-waters (0-4 m depth). A total of 34 species belonging to six taxonomic groups (Sipuncula, Oligochaeta, Polychaeta, Crustacea, Mollusca, and Pisces) were found within the dead shells of four P. nobilis individuals. The mass mortality of Pinna nobilis in the Sea of Marmara, the last remaining disease-free sea, indicates the necessity of establishing and implementing emergency action plans for this species, including ex-situ conservation.

Two-way bioinvasion: tracking the neritic non-native cyclopoid copepods Dioithona oculata and Oithona davisae (Oithonidae) in the Eastern Mediterranean Sea

Accelerated anthropogenic changes in the Eastern Mediterranean Sea (EMS) have facilitated the introduction, spread and establishment of invasive copepod species in this region. Here, we report the introduction of two non-native cyclopoid copepods Dioithona oculata and Oithona davisae for the first time in the Israeli coastal waters and describe their temporal variability. The species were identified by morphological characteristics, DNA barcoding and phylogenetic inference. Molecular identification and phylogenetic analysis supported the taxonomical identification, nevertheless, showed cryptic speciation within D. oculata, separating the Western Pacific and EMS clades. In the Israeli coastal waters, D. oculata presented a temporally restricted occurrence, appearing from September 2019 to December 2019 (30.0±0.7 – 21.0±1.1 °C) and October 2020 (28.0±0.7 °C). The highest abundances of D. oculata occurred in the autumn (October 2019 and 2020), when the water temperature reached 28.0 °C (7 and 10 ind. m-3, respectively). The lowest abundance occurred in December 2019 (0.35 ind. m-3), when the water temperature decreased to 21.0 °C, indicating that the thermal affinity of D. oculata for warm-temperate conditions, for reproduction and the maintenance of viable populations, has persisted in the introduced range. In contrast, O. davisae appeared almost all year around (17.0±0.5 – 28.0±0.7 °C). This species demonstrated peaks in abundance both in October 2019 and October 2020, when the water temperature reached 28.0 °C (406 and 92 ind. m-3), as well as when the temperature decreased to 17.0 °C (31 ind. m-3, February 2020), confirming its wide eurythermal tolerance. Based on our findings and previous observations, we suggest that D. oculata may have invaded the EMS through the Suez Canal and is now at the onset of its spread in the Mediterranean Sea, whereas O. davisae has been introduced via shipping, likely from the Northeast Atlantic, widely spreading and successfully establishing viable populations across the entire Mediterranean Sea, until the coastal Levantine Sea.

The use of fishers’ Local Ecological Knowledge to reconstruct fish behavioural traits and fishers’ perception of conservation relevance of elasmobranchs in the Mediterranean Sea

The Mediterranean Sea has a long-lasting history of fishery exploitation that, together with other anthropogenic impacts, has led to declines in several marine organisms. In particular, elasmobranch populations have been severely impacted, with drastic decreases in abundance and species diversity. Based on their experience, fishers can provide information on marine species occurrence, abundance and behavioural traits on a long-term scale, therefore contributing to research on the poorly studied biological aspects of elusive or rare elasmobranch species. In this study, for the first time, the use of the Local Ecological Knowledge (LEK) of fishers was applied to study the behavioural traits of sharks, rays and skates in 12 FAO-GFCM geographical sub-areas (GSAs) of the Mediterranean Sea. This study found both new insight and proved the reliability of LEK-based catch seasonality, reflecting seasonal movements, by comparing LEK-based findings and available literature on five elasmobranch taxa (Mustelus spp., Squalus acanthias, Raja spp., Myliobatis aquila and Scyliorhinus stellaris) in the Adriatic Sea and 7 taxa (Mustelus spp., Raja spp., Prionace glauca, Scyliorhinus canicula, Torpedo spp., Pteroplatytrygon violacea and Isurus oxyrinchus) in the remaining Mediterranean GSAs. In addition, LEK provided new insights into a novel comprehensive representation of species aggregations (Mustelus spp., S. acanthias, M. aquila and S. canicula) in the sampled GSAs and supplied the first descriptions of the size, number of individuals and sex composition of the aggregations. When the limits and shortcomings of LEK-based research are considered, this methodology can be a complementary and cost-effective tool used to study elasmobranchs in either a data-poor scenario or a scenario in which a baseline is missing. LEK can also be useful for the evaluation and inclusion of fishers’ perceptions on bottom-up management and to provide important evidence for conservation plans.

“New records of rare species in the Mediterranean Sea” (October 2021)

“New records of rare species in the Mediterranean Sea” (October 2021)

The Blue Survey: Validation of an instrument to measure ocean literacy among adults

Human activities have put the ocean under unprecedented pressure. Still, levels of public understanding about the ocean remain low. Ocean literacy is a global movement that aims to improve the understanding of the ocean and provide an incentive for positive change in people’s behavior. To date, there is no validated scale targeted to adults to measure ocean literacy that includes measuring people’s knowledge about the ocean, as well as surveying their attitudes and willingness to act. The Blue Survey is an online instrument meant to measure ocean literacy in adult populations developed by a multidisciplinary team of experts. Using factor analysis, we explore the validity and internal consistency of the Blue Survey in a purposive online sample of 251 adults. We found ocean literacy to consist of six sub-dimensions captured by 34 survey items, viz. knowledge of ocean-related topics, personal interest in ocean-related aspects, ocean stewardship, ocean as an economic resource, ocean-friendly behavior, and willingness to act responsibly for the ocean. Our analysis resulted in the development of a new validated instrument to measure the various dimensions of ocean literacy. It may help researchers and practitioners to better understand the factors contributing to shaping an ocean-literate person. Further research should assess the validity of the Blue Survey across different populations, including those closely related to the sea, such as maritime professionals.

Digital storytelling as an educational tool for scientific, environmental and sustainable development literacy on marine litter in informal education environments (Case study: Hellenic Center for Marine Research)

The modern era is characterized by the explosion of Information and Communication Technologies (ICT) and their multiple applications both in the school community and in the extracurricular activities. ICT enables the school community to be engaged in new educational storytelling approaches with educational and learning content, using multimedia applications. This article describes a study that took place at the headquarters of the Hellenic Center for Marine Research and involved a convenience sampling of 153 high school students (ages 13 to 15 years old). The study is aimed to investigate the use of digital storytelling in developing environmental and sustainability awareness and enhancing the scientific literacy of high school students when it is used as an instructional tool in informal learning, for marine litter, a serious environmental and sub-regional issue of our days. A didactic intervention was applied focusing on digital storytelling and experiential hands-on activities covering concepts of marine pollution, to establish the acquisition of new knowledge and the strengthening of optimal behavior towards the environment and sustainable development of attitudes towards the global problem of plastic marine pollution. The results of the study confirm the importance of digital storytelling for the cultivation of students' Scientific and Environmental Literacy for oceans.

A three dimensional, full life cycle, anchovy and sardine model for the North Aegean Sea (Eastern Mediterranean): Validation, sensitivity and climatic scenario simulations

We present the development of a 3D full-lifecycle, individual-based model (IBM) for anchovy and sardine, online coupled to an existing hydrodynamic/biogeochemical low-trophic level (LTL) model for the North Aegean Sea. It was built upon an existing 1D model for the same species and area, with the addition of a horizontal movement scheme. In the model, both species evolve from the embryonic stage (egg+yolk sac larva) to the larval, juvenile, and adult stages. Somatic growth is simulated with the use of a “Wisconsin” type bioenergetics model and fish populations with an adaptation of the ‘super individuals’ (SI) approach. For the reference simulation and model calibration, in terms of fish growth and population biomass, the 2000-2010 period was selected. Interannual biomass variability of anchovy was successfully represented by the model, while the simulated biomass of sardine exhibited low variability and did not satisfactorily reproduce the observed interannual variability from acoustic surveys. The spatial distribution of both species’ biomass was in relatively good agreement with field data. Additional single-species simulations revealed that species compete for food resources. Temperature sensitivity experiments showed that both species reacted negatively to a temperature increase. Anchovy, in particular, was more affected since its spawning and larval growth periods largely overlap with the period of maximum yearly temperature and low prey concentration. Finally, simulation experiments using IPCC climatic scenarios showed that the predicted temperature increase and zooplankton concentration decrease in the future will negatively affect anchovy, resulting in sardine prevalence.

Tracing the occurrence of ocean sciences issues in Greek secondary education textbooks

This study aims to investigate the presence of ocean sciences issues in Greek secondary education (grades 7-12) science textbooks, in respect of the Ocean Literacy Framework. Content analysis was undertaken concerning both textual and pictorial materials of the Biology, Chemistry, Physics, and Geography – Geology courses. Results revealed that the textbooks under study contain limited and fragmented information with regard to the seven essential principles of the framework, while a comparison with the Ocean Literacy Scope & Sequence evidences inconsistencies. The suggestions arising from this study could help curriculum designers, textbook authors, marine educators, and marine scientists to cooperate on a wider scale towards the inclusion of ocean literacy topics into national curricula worldwide.