The confirmed occurrence of two specimens of Remora remora (Linnaeus, 1758) from Mersin Bay (NE Mediterranean, Turkey)

Remoras attach to sharks, big fish, and sea turtles and continue their lives with these creatures. Kapızlı and Tekeli beaches are located near Göksu Delta and Anamur nesting areas of Caretta caretta. In this study, two Remora individuals were caught with a fishing rod in July, when the ovulation was most intense. The smaller remora individual (33 cm) was caught from the coast of Tekeli with the chicken breast at a depth of 2.5 m, and the larger one (66 cm) with bread at a depth of 1.5 m from Kapızlı beach on 24.07.2020. The two Remora individuals caught were probably attached to the sea turtles. However, probably due to sea turtles going to the beach to lay eggs, Remoras started to free-swimming, and they were caught with the fishing line since they could not be fed. The present study reported that the first occurrence of Remora specimens is probably attached to turtles for Turkey's northeastern Mediterranean coast. Besides, this study is provided some morphometric and meristic data on this species and discussed a probable host of these specimens.

Pinna nobilis in the Greek seas (NE Mediterranean): on the brink of extinction?

The Mediterranean endemic fan mussel Pinna nobilis is suffering an ongoing basin-scale mass mortality event (MME) since 2016. As most Mediterranean populations have collapsed, the species has been declared as Critically Endangered in the IUCN Red List of threatened species. In an effort to track the progress of the MME and provide updated information on the status of the species in the Greek seas, we compiled data collected through dedicated surveys and opportunistic assessments during 2019 and 2020. A total of 14589 fan mussel individuals, of which 81.1% dead, were recorded in 258 site surveys. Of the remaining 2762 live individuals, 256 were juveniles. Two marine areas which still sustain living populations were identified, namely Kalloni Gulf (Lesvos Island), and Laganas Bay (Zakynthos Island). The inner part of Kalloni Gulf appears to maintain the largest surviving population of the species in the eastern Mediterranean, with an abundance estimate of 684000 individuals (95% confidence interval: 322000-1453000). Solitary, potentially resistant, scattered individuals were recorded in several sites. Other previously abundant populations that had been assessed in the past, specifically those of Lake Vouliagmeni (Korinthiakos Gulf), Souda Bay (Crete) and Gera Gulf (Lesvos Island), and which collectively summed up to ~350,000 individuals, have now been wiped out. Our results document the collapse of most P. nobilis populations throughout the Greek seas. The MME has substantially progressed between early 2019 and mid-2020, as indicated by the increase of mortality at sites consecutively monitored multiple times. This work highlights the urgent need for continuous monitoring of surviving populations and calls for the immediate implementation of an effective protection and management strategy that will ensure the persistence of surviving individuals and the production of resistant offspring.

Grazing effect of flagellates on bacteria in response to phosphate addition in the oligotrophic Cretan Sea, NE Mediterranean

ABSTRACT The planktonic food web in the oligotrophic Mediterranean Sea is dominated by small-sized (<20 μm) microbes, with nanoflagellates being the major bacterial grazers and the main participants in nutrient cycling. Phosphate is a key nutrient in the P-limited Cretan Sea (NE Mediterranean) and P-availability can affect its trophic dynamics. Here, we examined the grazing potential of heterotrophic (HF) and pigmented (PF) nanoflagellates as a response mechanism to phosphate amendment. Flagellate grazing effect on bacteria was quantified in P-amended nutrient-depleted water from the Cretan Sea over the course of 4 days using microcosm experiments. P-addition positively affected HF abundance, while PF abundance remained unchanged. At the community level, P-addition had a negative effect on PF bacterial removal rates. In the control, PF-grazing rate was significantly higher than that of HF throughout the experiment. Pigment analysis showed no changes in phytoplankton community composition as a result of P-addition, indicating that PF grazing rate declined as a physiological response of the cells. The present study emphasizes the dominant grazing role of PF under P-depleted conditions and reveals that during the late stratified season PF respond to P-addition by lowering their grazing rates, enhancing the relative importance of bacterial removal by HF.

Deep-water shipwrecks in the East Mediterranean: a microcosm of Late Roman exchange

Deep-water shipwrecks provide an opportunity to investigate ships away from the destructive dynamics of coastlines and approaches to harbors where most ancient wrecks to date have been found. Such exploration expands the potential for finding wrecks of periods for which relatively few are known. One such period is the 6th and 7th c. in the E Mediterranean. Studies of cargo assemblages from the few known wrecks of the later Roman period reveal a partial picture of interlinked and overlapping trade networks that incorporated major and minor ports in the adjacent provinces.1 Various trading modes may be discerned, including cabotage, short-haul trade, inter-regional commerce, and private long-haul trade. Largely missing thus far are the wrecks of ships that participated in the annona transport, the “backbone of Late Roman shipping”.2 Each year, an enormous fleet of private ships under state contract hauled thousands of shiploads of Egyptian grain from Alexandria to Constantinople for public distribution,3 but no shipwrecks explicitly associated with these fleets have been found. Also largely invisible are the non-commercial transports associated with the annona militaris, the fiscal supply of foodstuffs destined for armies stationed on the empire‘s borders. The state supply-system became more formalized in 536 when Justinian created the quaestura exercitus, a prefecture that was granted administrative control and jurisdiction of Moesia Secunda, Scythia, Caria, the Aegean islands, and Cyprus.4 Evidence suggests that the quaestor‘s main task was to ensure the supply, by sea, of agricultural products from the Aegean and NE Mediterranean to troops on the Danube frontier.5 While no definitive grain ships have been found in the E Mediterranean — what M. McCormick has called the “annona paradox”6 —, shipwrecks with the larger cargoes expected of state supply have remained rather elusive.

Reproductive biology of Charybdis (Goniohellenus) longicollis Leene, 1938 (Brachyura: Portunidae), in the north-eastern Mediterranean Sea, Turkey

The swimming crab, Charybdis (Goniohellenus) longicollis Leene, 1938, is a Lessepsian migrant into the Mediterranean and little is known about its biology in Iskenderun Bay, north-eastern Mediterranean, Turkey. The size of crabs, sex-ratio and spawning period of this species was defined from 951 specimens in order to understand their reproduction and development in the NE Mediterranean Sea. The crabs were found to occur throughout the year. Carapace width (CW) ranged between 7.22 to 100.60 mm and total weight ranged from 1.34 to 164.09 g. Male-female sex ratio was 0.6:1. Highest gonado-somatic index (GSI) was seen in March and September for females and in May for males. Ovigerous females were present throughout the year, with peak spawning activity in July and September. The CW of the ovigerous female crabs ranged between 23.71 and 95.93 mm. In winter months, GSI of males and females decreased. However, spawning season of C. (G.) longicolis in Yumurtalık Cove was observed throughout the year.

“Crash landing” obligation for Mediterranean mixed fisheries: Evaluation of management strategies using bioeconomic modelling in the Aegean Sea

Minimizing unwanted catches is a major milestone for achieving sustainable fisheries. In the framework of the Common Fisheries Policy, a landing obligation is being established progressively in European waters (Article 15, EU Regulation 1380/2013). Supplementary management measures have been proposed to support and enhance the effectiveness of this new regime. In this context, the effect of the landing obligation on a demersal mixed fishery (coastal and trawl fleet) in the Aegean Sea (NE Mediterranean Sea) was assessed in terms of both biological and economic sustainability. Our results show that the landing obligation alone does not ensure sustainable fisheries. Management action should be directed to the introduction of additional measures. Evidence suggests that improving selectivity and protecting the nursery grounds are possible solutions to decrease discards and ensure sustainable fisheries in the long term. The landing obligation can have a role in incentivizing the adoption of these management measures that ensure lower fishing mortality on juvenile fish.

Coralligenous formations dominated by Eunicella cavolini (Koch, 1887) in the NE Mediterranean: biodiversity and structure

Coralligenous formations are biogenic structures typical of the underwater Mediterranean seascape. Their intricate, multi-layered species assemblages are composed of perennial, long-lived organisms, particularly vulnerable to natural or human-induced disturbances. Despite their high ecological role and conservation value, few studies have addressed the assemblages outside the NW Mediterranean. This is the first quantitative assessment of coralligenous in the N Aegean Sea (NE Mediterranean), specifically focusing at the upper bathymetric limit of assemblages that are dominated by the yellow gorgonian Eunicella cavolini. The number and percent cover of macrobenthic species were studied at depths of 18 to 35 m, using a photoquadrat method. A total of 99 benthic taxa were identified, out of which 89 perennial ones were used to investigate spatial patterns in assemblage structure, composition, and biodiversity. A mean number of 47 perennial taxa were recorded per site, with encrusting coralline algae and sponges being the dominant groups in percent cover and species number, respectively. Across the studied localities, structural complexity and community composition were overall similar, but assemblages presented distinctive differences at the level of sites highlighting the role of local abiotic and anthropogenic factors in the shaping of the coralligenous. Compared to the rest of the Mediterranean, assemblages hosted a similar number of taxa. However, the number and percent cover of erect bryozoans were generally low, while, apart from E. cavolini, other erect anthozoan species were absent. This work provides an important baseline for comparisons and monitoring at a local or Mediterranean scale level.

Epilithic diatom communities from areas of invasive Caulerpa species (Caulerpa taxifolia and Caulerpa cylindracea) in the Adriatic Sea, NE Mediterranean

Epilithic diatom community structures are compared among three locations of the eastern Adriatic Sea coast (Croatia), in the presence of two different invasive Caulerpa species, C. taxifolia and C. cylindracea, which have spread rapidly in the Mediterranean in the last decades. Forty samples were taken seasonally at three sites (island of Hvar, island of Mljet, and Dubrovnik) between November 2008 and October 2010. Light and electron microscopy examinations were used for qualitative analysis. Altogether 310 epilithic taxa belonging to 65 genera were identified. The highest number of these taxa belonged to Mastogloia (48) and Amphora (32), followed by Diploneis (24), Nitzschia (23), Navicula (22), and Cocconeis (19). A similar seasonal shift in growth form structure was observed for epilithic communities at the three sampling sites, where the number of erect group diatoms doubled (Hvar, Mljet) and tripled (Dubrovnik) in spring. Apart from erect forms, Dubrovnik and Mljet were characterised by adnate forms, while Hvar was characterised by tube-dwelling forms. The highest values of the Shannon-Wiener Diversity Index were recorded in autumn and ranged from 5.26 to 5.34. ANOSIM tests performed on species relative abundance data confirmed that the diatom communities differed significantly between the sampling sites, and that the differences were correlated with the presence of the two species of invasive macroalgae (Hvar – area of C. taxifolia; Mljet and Dubrovnik – areas of C. cylindracea). As revealed by SIMPER analyses, the group of taxa contributing the most to variance between diatom assemblages from sites of different invasive alga included Cocconeis scutellum var. scutellum, Rhopalodia pacifica, Navicula ramosissima, and Berkeleya rutilans. Although the spatial variation in communities may also reflect the effects of unmeasured environmental variables, the results suggest the possible influence of invasive seaweeds of the genus Caulerpa which may affect the habitat by competing with autochthonous algae. This study contributes to the knowledge of diatom diversity both at regional and at broader scales in these challenged environments.