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During the cultivation of Ulva fenestrata in a land-based aquaculture system, the colonisation of the water tanks' surfaces and eventually the macroalgal biomass by the biofouling diatom Fragilariopsis oceanica compromises the production process. Since germanium dioxide (GeO2) is an effective growth inhibitor of diatoms, this study aimed to understand how it affects the presence of F. oceanica and the photosynthesis and growth of U. fenestrata as a primary parameter contribution to the biomass production. A toxicological dose-response experiment showed that the diatom's growth was inhibited at the low GeO2 concentration of 0.014 mg l−1. In contrast, the photosynthetic performances and growth rates of U. fenestrata remained unaffected under a wide GeO2 concentration range (0.022–2.235 mg l−1) in small- and large-scale experiments in 1-l glass beakers and 100-l Plexiglass water tanks, respectively. In the latter, the diatom density in the tanks was reduced by 40 %. The costs arising from the use of GeO2 can range between €2.35 and €8.35 kg−1 fresh weight of produced U. fenestrata biomass under growth conditions resulting in growth rates of 20 and 11.5 % d−1, respectively. GeO2 is an effective agent to control biofouling diatoms such as F. oceanica during the land-based biomass production of U. fenestrata. [ABSTRACT FROM AUTHOR]

Marine prairies play various crucial roles in marine ecosystems. The seagrasses that compose them are one of the most important components engineering the marine coastal system, providing significant spatial niches. Some of the seagrasses found in marine prairies are protected, and it is not recommended to sample them with destructive methods. Non-destructive methods such as remote sensing have been proposed as important means of studying these protected species. In the present study, the acoustic scattering properties of Cymodocea nodosa were studied with two different in/ex situ experiments conducted on a Turkish Mediterranean coast using a scientific echosounder (206 kHz split beam transducer) in different months over the years 2011 and 2012. After a series of acoustic processes, correlations and regression equations were established between different acoustic parameters of the Elementary Distance Sampling Units and biometric traits of below/above ground parts of the seagrass. The relationships were logarithmically established producing first a Rayleigh zone, followed by a geometrical zone that occurred with increased biometrics. No seasonal difference occurred in the relationships for the above-ground parts. Unlike the leaves, seagrass sheaths demonstrated unstable echo energy, inconsistent relationships, and unexplained acoustic responses over the span of several months. Regarding leaf density changing in time, significant relationships were explained as a function of the acoustic zones. Four points were highlighted to explain the differences in the estimations between the two experiments; i) the backscattering strengths depended on strength of biomass and its fractions (leaf area, shoot density and volume) between the two experiments, ii) the first experiment measured backscattering strength from individual specimens, but the second experiment was performed on the total biomass of seagrass per unit area, iii) different frequency response to the biometrics occurred in the two experiments, and iv) the non-linear effect of the sheath could not be separated from that of the leaf during the second experiment. The present study was the first attempt to characterize relationships between the biometric and acoustic backscattering properties of C. nodosa, and will guide researchers in future use of non-destructive methods. [ABSTRACT FROM AUTHOR]

Halophila stipulacea is an invasive seagrass in the Caribbean Sea that also harbors a phytomyxid endoparasite. Phytomyxean parasites are known to cause disease in agricultural crops and are documented to form galls in some seagrass species. Here we make the first report of phytomyxid infection of Halophila stipulacea in the Bahía de Jobos in Salinas, Puerto Rico. We found phytomyxid infected H. stipulacea at 3 of 5 sites examined, expanding the documented range of the Marinomyxa marina phytomyxid infection by almost 400 km from where it was first documented in 2018. Presence of the endoparasite has not impeded H. stipulacea dispersal and continued expansion of H. stipulacea will likely spread both the host seagrass and the endoparasite. [ABSTRACT FROM AUTHOR]

The "tropicalization" of the Mediterranean Sea refers to the increasing appearance of thermophilous species throughout the Mediterranean Sea and is described as a combined effect of four different phenomena: introduction of NIS of tropical Atlantic origin, Lessepsian immigration, man-made introductions and sea-water warming ([11]). Keywords: Croatia; Cyprus; Greece; seagrasses; seaweeds; Turkey EN Croatia Cyprus Greece seagrasses seaweeds Turkey 221 230 10 08/09/22 20220801 NES 220801 1 Background To track the history behind this special issue, we should go back to February-March 2009, when a group of phycologists (Christos Katsaros, Frithjof C. Küpper, Konstantinos Tsiamis, Dieter G. Müller, Hiroshi Kawai, Martina Strittmatter and Maria Karadanelli; Sotiris Orfanidis and his group were not able to participate in the Lesbos trip, but subsequently played a very active role in the consortium project) paid a visit to Lesbos Island (Aegean Sea, Greece), and for three weeks made field trips to different coasts, exploring the marine flora of the area. However, further overall progress in Mediterranean seaweed taxonomy and biogeography is hampered by limited coverage of Mediterranean taxa by DNA barcode sequences ([7]). Salinity tolerance of the Mediterranean seagrass Posidonia oceanica: recommendations to minimize the impact of brine discharges from desalination plants. 2 East Mediterranean seaweed biogeography and taxonomy About 270 taxa of brown algae had been recorded in the Mediterranean Sea by 2012 ([15]; [70]). [Extracted from the article]

Keywords: Eastern Mediterranean Sea; Posidonia oceanica; satellite; seagrass; sidescan sonar; wide-scale mapping EN Eastern Mediterranean Sea Posidonia oceanica satellite seagrass sidescan sonar wide-scale mapping 289 299 11 08/09/22 20220801 NES 220801 1 Introduction Seagrasses constitute a group of submerged flowering plants that can be found in shallow marine and brackish waters in many parts of the world, from the tropics to the Arctic Circle ([17]; [43]). In this plot, a more homogeneous coverage pattern emerges, with a mean of 0.25 ± 0.13 km SP 2 sp of seagrass meadow per km of coastline in all mapped meadows of the N. Aegean Sea. An effort to map Greek meadows using only satellite data by [41] led to an estimate of 2613.88 km SP 2 sp of seagrass meadows. 3 Results and discussion 3.1 Spatial distribution and surface area of seagrass meadows The presence of seagrass meadows was recorded along approximately 70% of the Greek coastline, with their total areal extent estimated at 2749.07 km SP 2 sp . [Extracted from the article]

Keywords: marine algae; marine flora; Mediterranean Sea; Turkey EN marine algae marine flora Mediterranean Sea Turkey 231 241 11 08/09/22 20220801 NES 220801 1 Introduction Turkey is washed by four seas of different oceanographic character (i.e., sea surface salinities in the Black Sea, the Marmara Sea, and on the coasts of the Aegean and the Levantine are 14-18, 20-24, and 35-38, respectively, and the corresponding temperatures are 8-11 °C, 10-12 °C, and 13-18 °C). Marine algae, marine flora, Mediterranean Sea, Turkey Taxonomy and distribution of Fucales (Phaeophyta) members on Aegean and Mediterranean coasts of Turkey. Graph: Figure 3: (a) Total taxa of marine macroalgae and (b) the relative contribution of different orders on the Aegean and the Levantine coasts of Turkey. The purpose of this paper is to present a current review of benthic marine algal species reported from the Aegean and Levantine coasts of Turkey, and also to report the occurrence of the marine red alga I Palisada maris-rubri i for the first time from the eastern Mediterranean coast of Turkey. [Extracted from the article]

For example, rainfall was shown to enhance seagrass biomass in an Australian seagrass meadow on Mabuiag Island (where the seagrass community includes species from the genera I Cymodocea, Halodule, Thalassia, Halophila, Enhalus, i and I Syringodium i ) throughout a 30-day trial ([92]). Organic carbon in seagrass sediments is influenced by seagrass canopy complexity, turbidity, wave height, and water depth. Keywords: chlorophyll a fluorescence; factorial experiment; growth rate; North Aegean Sea; seagrass EN chlorophyll a fluorescence factorial experiment growth rate North Aegean Sea seagrass 301 313 13 08/09/22 20220801 NES 220801 1 Introduction Seagrasses are flowering, rooted plants that form extensive meadows in shallow sandy to muddy coastal waters worldwide ([39]), receiving about 10-20% of the incident irradiance at the water surface ([31]; [32]). I Cymodocea nodosa i (Ucria) Ascherson is a common seagrass species in the Mediterranean Sea and in the Canary Isles ([32]) that grows relatively fast compared to other seagrass genera ([94]). High-salinity brine discharges from seawater desalination plants can also negatively impact seagrass meadows [103]. [Extracted from the article]

These include I Ulvella i spp. from the Ulvales, I Ostreobium i and I Pseudochlorodesmis i spp. from the Bryopsidales and some species of I Chaetomorpha i from the Cladophorales ([27]; [45]; [50]). Moreover, new insights are provided about the epiphytic and endophytic algal species growing on macrophytes, including I P. oceanica i , I Halopteris i sp. and I Dictyopteris i sp. in the central Mediterranean Sea. We also update the Maltese macroalgal species checklist ([5]) from 340 species to 342 species through the addition of I U. endostraca i and I B. rhizopus i . Keywords: Blastophysa rhizopus; DNA barcoding; germling culture; Ulvella; Ulvophyceae EN Blastophysa rhizopus DNA barcoding germling culture Ulvella Ulvophyceae 243 254 12 08/09/22 20220801 NES 220801 1 Introduction Various inaccuracies have occurred in past classifications of micro-filamentous genera belonging to the Ulvophyceae, due to the occurrence of cryptic taxa. [Extracted from the article]

Cymodocea nodosa, a typical marine angiosperm species in the Mediterranean Sea, hosts a range of epiphytic algae. Epiphyte abundance varies at different spatial scales, yet epiphyte diversity and community composition are poorly understood. This study explores the epiphytes on C. nodosa from two reference meadows (Thasos, Vrasidas) and one anthropogenically stressed meadow (Nea Karvali) in the northern Aegean Sea (Kavala Gulf, Greece). A nested destructive sampling design at three spatial scales (metres, hundreds of metres, kilometres) and stereoscopic/microscopic observations were used. Light microscopy revealed a total of 19 taxa of macroalgae populating the leaves of C. nodosa. The most commonly encountered taxa with highest cover (%) were Hydrolithon cruciatum and Feldmannia mitchelliae. DNA sequencing (18S rDNA) confirms the presence of a number of dinoflagellate and red algal epiphytes, and this represents the first application of DNA metabarcoding to study the diversity of seagrass epiphytes. Epiphytic communities studied at species/taxon and functional (Ecological Status Groups) levels separated the reference low-stressed meadows from the degraded one, with the functional approach having higher success. The ecological evaluation index classified the studied meadows into different Ecological Status Classes according to anthropogenic stress. [ABSTRACT FROM AUTHOR]

Halodule wrightii meadows in Southern Brazil have been regressing in an unsheltered area of the subtropical Paranaguá Bay, near their southern limit in the SW Atlantic, since 2006. To identify early indicators of regression events, we assessed variations in plant and macrobenthic structure in two local meadows under unsheltered and protected conditions. Differences between sites increased after an epiphytic overgrowth of the alga Hincksia mitchelliae at the unsheltered site. Seagrass growth was suppressed and the numbers of burrowing and opportunistic benthic species increased with the increase of algal biomass. In the protected meadow, seagrass biomass and number of leaves changed seasonally, but macrobenthic abundance and species richness remained stable. Ecosystem changes were evident when the unsheltered meadow was already collapsing. The number of leaves per shoot, the horizontal internode length, the abundance and structure of the macrofaunal associations, and the host-epiphyte surface interactions, were the first variables to reflect the early stages of seagrass regression. Our results suggest that the persistence of H. wrightii meadows at their southern distribution limit in the SW Atlantic will be affected by local hydrodynamics and their ability to compete with ephemeral macroalgal species under stress conditions. [ABSTRACT FROM AUTHOR]

Although extensive studies have been made on Posidonia oceanica ecosystems, in terms of their phenological characteristics, shoot density, biomass, and associated faunal assemblages, little attention has been given to the depth distribution of this species in the Adriatic Sea. The depth limits of the Mediterranean endemic seagrass P. oceanica growing along the eastern coast of the Croatian Adriatic Sea were examined by the use of SCUBA diving. Fifty-two independent measurements show that the lower depth limit of P. oceanica in the Croatian Adriatic Sea ranges from 24 m in the north to 36 m in the south, with a strong latitudinal gradient. The information on maximum depth distribution is an important asset when the increased human pressure and rapid environmental changes pose a threat to the survival of this slow-growing marine species. [ABSTRACT FROM AUTHOR]

The importance of thallus fragmentation in the recruitment of the invasive, introduced alga Caulerpa racemosa (Forsskål) J. Agardh at the margins of Posidonia oceanica (L.) Delile beds was studied. A multifactorial experiment was designed to estimate the importance of detachment time on the seasonality of establishment of vegetative fragments and whether this pattern was consistent at different temporal and spatial scales. The approach consists of dispersing drifting fragments of Caulerpa racemosa, detached from substratum 0, 5 and 10 days before, along the margin of a bed of Posidonia oceanica and recording the number of fragments established after 1 month. The results showed that a large number of fragments became established in this habitat and that the greatest number of fragments were found during summer. Surprisingly, the time of detachment from substrate was not found to influence the probability of success in establishment. The results of this study indicated that dispersal by fragmentation is likely to contribute to the wide spread of this alga in the Mediterranean Sea. The spread of this alga via fragmentation is predicted to be the greatest during summer when the largest proportion of fragments are re-established. Geographical patterns of dispersal can thus be interpreted on the basis of this reproductive strategy, of hydrographic studies and experimental evaluation of resistance of fragments to desiccation and drift. The results obtained in this study, together with those obtained at another site using the same experimental approach for Caulerpa taxifolia (Vahl) C. Agardh, suggest that vegetative fragmentation plays a large role in the dispersal of rhizophytic introduced fast-spreading species in the Mediterranean Sea. This reproductive strategy would be in accordance with invasive and fast-spreading abilities exhibited by members of the Bryopsidales. [ABSTRACT FROM AUTHOR]

An experiment using cages was designed to demonstrate herbivore consumption of Posidonia oceanica (L.) Delile reproductive structures, in a north-western area of the Mediterranean Sea. The percentages of mature inflorescences and those damaged by herbivores in caged vs. uncaged (control) vs. partially caged plants (artefact control) were compared. Inflorescences damaged by herbivores were 84.3±3.1% in the control and 79.5±3.2 % in partial cages. Significantly more mature inflorescences were found in caged (37.5±2.4%) vs. uncaged (10.1±2.9 %) and partially caged plants (6.7±0.9 %). The real contribute of herbivores to the loss of fertilised inflorescences of P. oceanica was approximately 27 %, as the differences between mortality in caged and in uncaged plants. These results suggest that herbivores could affect sexual reproduction in P. oceanica, but further investigation is needed to investigate biotic interactions in the meadows. [ABSTRACT FROM AUTHOR]

Examines the effects of mercury on glutathione S-transferase activirty in the marine phanerogram Posidonia oceanica in the Mediterranean Sea. Analysis of mercury uptake in the photosynthetic parts; Increase in glutathione S-transferase (GST) activities in foliar tissues; Measurement of the GST activities.

The seagrass Posidonia oceanica is able to reproduce by asexual formation of plantlets directly in the inflorescence. Pseudoviviparous plantlets were observed during May 2004 in 26% of the inflorescences in a P. oceanica meadow off the island of Formentera (Balearic Islands, Western Mediterranean Sea). We do not know how frequently pseudovivipary occurs in Posidonia oceanica , nor the mechanisms triggering it, but this strategy can contribute significantly to short-distance dispersal and meadow maintenance, which is especially relevant in a species whose meadows can persist for thousands of years and whose colonization of new space occurs very slowly. [ABSTRACT FROM AUTHOR]