Seasonality and phenology of an epiphytic calcareous red alga, Hydrolithon boreale, on the leaves of Posidonia oceanica (L) Delile in the Turkish water.

Epiphytes on Posidonia oceanica play a crucial role for determination of the ecological status of marine environment in time and space besides the seagrasses alone. The study was aimed to estimate the spatiotemporal ecological status linked to variation in biometry of an epiphytic micro-calcareous red alga, Hydrolithon boreale, found on leaves of the meadow with the exclusive environmental parameters along the entire Turkish coast of the Mediterranean Sea. Collection of Posidonia oceanica samples was conducted at 64 stations in winter (December 2018-January 2019) and 112 stations in summer (June-July 2019) by SCUBA (0.4 × 0.4 m of a quadrate frame) in the infralittoral zone along the entire Turkish Mediterranean coast surrounded by the siliciclastic Taurus Mountain Range which favor growth of epiphytic micro-calcareous red algae. Percent occurrence of the epiphyte changed seasonally-lower in winter (25%) than in summer (44%). The epiphyte which is an indicator and sensitive to undisturbed marine area grew up well to 5 mm in diameter, 0.35 mm in thickness of the crust size, and was populated up to 1006 ind/m2 in summer owing to the increased utilization of the carbonate by the epiphyte with the increased water temperature. The size was contrasted to the density (abundance and biomass) in space. The biometry was significantly dependent on the siliciclastic-carbonate deposition as inferred from SiO4-Si of the water in relation to the leaf area index (LAI) of P. oceanica. Therefore, this deposition induced specimens to grow in size, followed by the reduced density concerning the N-based nutrient of the water. Further major environmental parameters which negatively affected the biometry were pH and total suspended matter of the water, analogous to turbidity. Of the trace elements, Ni was negatively correlated with the biometry, whereas the LAI was however positively correlated with all the anthropogenic-sourced trace elements (V, Cu, Zn, As, Cd, and Pb) in the leaves. Of the bottom types, the calcite rock had a higher density than the other soft bottoms in contrast to the size of the epiphyte. Future studies could be based on the present study for determination of the ecological status regarding two dominant epiphytes on leaves of two seagrasses (H. boreale on P. oceanica and partly Pneophyllum fragile on Cymodocea nodosa) found in the different environments and substrates in space and time.

The broad-scale microplastic distribution in surface water and sediments along Northeastern Mediterranean shoreline.

Plastics manufactured to fulfil the unique demands of civilization accumulate in the sea due to their durability. Microplastics (MP) pose a greater threat than macroplastics as they can easily enter the aquatic environment and be hard to detect. MPs potentially impact several components of the marine life and food chain. This study determined MP distribution and characterization by collecting sediment from 47 different stations and surface seawater (SSW) from 29 stations in 2019 along the Turkish coast of the Eastern Mediterranean Sea. Potential MP particles were stained with Nile-Red and verified using ATR-FTIR. While MP abundance in the sediment ranged between 118 ± 97 and 1688 ± 746 MPs kg-1, it varied between 0.18 ± 0.10 MPs m-3 and 2.21 ± 1.75 MPs m-3 in SSW. The MP abundance showed significant spatial variation (p < 0.05). The polymer type in the samples was determined by ATR-FTIR. In both water and sediments, polyethylene was the most common MP type (>59 %), while fragment was the most common MP form (>57.6 %), and >65 % of overall MPs were <1500 µm. The spatial pattern of MPs in the sediments and SSW was affected by the population, the magnitude of the tourism sector, the rim current, and circulation. The monitoring data presented here can provide a remarkable projection of the current trend and form a basis for future MP pollution prevention.

Comparative trace element trends in Posidonia oceanica and its sediments along the Turkish-Mediterranean Sea coast.

Concentrations of eight trace elements (V, Cr, Ni, Cu, Zn, As, Cd, and Pb) were investigated in Posidonia oceanica leaf blades and sediments sampled from 23 stations along the Turkish-Mediterranean Sea coast. Trace element (TE) concentration in both sediment and P. oceanica showed a statistically significant distribution among sampling stations. Most of the TE concentration in samples varied remarkably among stations without a consistent trend. Concentrations of Zn, Cd, Cu, and Pb in the sediment of all of the sampling stations were determined as non-polluted based on the comparison with the sediment quality guideline index. More than a quarter of the sampling stations were found as moderately or heavily polluted for Cr, Ni, and As. The mean TE concentrations found in the sediment sample in the present study were similar to the concentrations reported from the different parts of the eastern Mediterranean Sea. TE concentrations in P. oceanica were generally lower compared to the concentrations in the sediment except for Cd, Zn, and Cu. While a positive correlation was found for Ni concentrations between sediment and P. oceanica samples, negative correlation was detected for V, Cr, Zn, Cu, As, and Cd concentrations between sediment and P. oceanica. The highest bioaccumulation factor in P. oceanica was calculated for Cd. The study area of the present study, especially the western sites (provinces of Antalya and Mugla), hosts millions of tourists annually and under the influence of intensive human activities in summer. Thus, coastal waters are heavily exposed to TEs and significantly positive correlations were detected between the anthropogenic TE pollutants (As, Cd, Cu, Zn, Pb, and V) and natural sourced TE (Ni and Cr). Based on our data, the Mediterranean Sea coast of Turkey does not present significant levels of Zd, Cd, Cu, and Pb pollution, whereas 65% of the stations were heavily polluted with As. Since As categorized as carcinogenic to humans, seafood sources should be monitored in terms of As concentrations. The current data might be useful in further TE-monitoring studies and TE discharge management strategies.

Macro litter distribution of the Turkish Mediterranean coasts dominated by pleasure crafts.

Litters are the most pollutants in progress of the interests in marine environments. Macro litter samples were collected from 66 stations to estimate litter contribution from pleasure crafts along bays of the most Turkish touristic coasts (Antalya-Mugla) by the divers in June/July 2019. Average abundance and weight were 19 items/km2 and 18 kg/km2, respectively. The most abundant litter was plastics and the most contributors in weight were metals, followed by glass/ceramics. Abundance of the litters increased with number of pleasure crafts in active in summer. Pleasure crafts contributed most abundantly with the personal wares to the total litter, particularly in the coasts of Mugla. Litters were differentiated with interaction of region × bottom depths. The litter composition and abundance were different between region of Antalya in active mostly by tour boats and region of Mugla by private yachts. The litter types were however correlated with sea surface temperature.