The use of storm fragments and biodegradable replanting methods allows for a low-impact habitat restoration method of seagrass meadows, in the eastern Aegean Sea

Seagrasses are important marine ecosystems but are vulnerable to physical damage from anthropogenic activities such as anchoring and trawling. Replanting damaged areas can represent a viable restoration strategy, yet current methods rely on the removal of plants from existing meadows and in some cases the use of non-sustainable planting materials. In this paper, we present evidence of a sustainable replanting strategy. Storm fragments of the endemic Mediterranean seagrass, neptune grass Posidonia oceanica were collected from the shore and shallow water, both the plagiotropic and orthotropic (horizontal and vertical) growth forms were then replanted using one of two biodegradable materials, coconut fibre pots or bamboo stakes, to secure them to the seafloor. Establishment of plagiotropic fragments were increased by bamboo anchorage (x̅ = 89% SE ± 0%) compared to orthotropic storm fragments (x̅ = 66.5% SE ± 6.5%). By contrast a coconut fibre method resulted in greater establishment of orthotropic fragments (x̅ = 79% SE ± 7%) compared to plagiotropic (x̅ = 51% SE ± 11%). Fragments showed some blade growth, but little shoot growth after 15 months. The fragment shoot and blade growth did not differ between the plagiotropic or orthotropic fragments replanted by bamboo stakes or coconut fibre pot. Our results suggest that the use of storm fragments and biodegradable anchoring materials constitutes a viable, non-destructive replanting technique in seagrass restoration. Furthermore success can be increased by selecting a growth-form appropriate planting method

Is All Seagrass Habitat Equal? Seasonal, Spatial, and Interspecific Variation in Productivity Dynamics Within Mediterranean Seagrass Habitat

Seagrass meadows’ ability to capture carbon through sequestering autochthonous carbon via photosynthesis means they could represent a potential nature-based solution to rising carbon emissions. In multispecies seagrass communities, and due to species introduction or predicted range shifts, it is important to know which species deliver different carbon sequestration gains to inform conservation actions. Large benthic chamber experiments (volume = 262L) assessed the seasonal and spatial variation in metabolism dynamics of the endemic and dominant Mediterranean seagrass, P. oceanica whilst small benthic chamber experiments (volume = 7L) compared the dynamics between, P. oceanica the native C. nodosa and non-native H. stipulacea. Within shallow P. oceanica edge habitat lower Net Apparent Productivity (NAP) occurs in autumn ((Formula presented.) = 1.3, SD ± 2.95 O2 mmol m-2 d-1) compared to summer ((Formula presented.) = 9.9, SD ± 2.75 O2 mmol m-2 d-1 corresponding with periods of light limiting and light saturating conditions, but it remains overall autotrophic annually (2.3 C mol m-2 yr-1). However, spatial heterogeneity exists, the center areas of P. oceanica were more productive (NAP (Formula presented.) =19.7, SD± 3.83 O2 mmol m-2 d-1) compared to edge habitat with spatial changes in productivity relating to plant surface area (96%), shoot density (81%), blade length (72%) and seagrass percentage cover (64%). Under comparative conditions in a sparse multispecies area of the meadow the species demonstrated different capacities for carbon fixation. H. stipulacea was carbon positive and P. oceanica fluctuated between positive and negative carbon balance suggesting both can maintain a balance between carbon fixation and carbon utilised for metabolic activity. In contrast the C. nodosa here would be expected to deteriorate as it was utilising carbon more than it was fixing (NAPN2 ((Formula presented.) = -0.0012, SD ± 0.0007 O2 mmol cm-2 d-1). This study demonstrates that not all seagrass habitat is equal. If seagrass meadows are to play a part in mitigating CO2 emissions, variability in primary productivity within seagrass meadows needs to be accounted for to produce accurate total fixed carbon estimates, and subsequently autochthonous carbon sequestration estimates. This means seagrass meadow species composition and the condition of these meadows must be better understood

Environmental variables influencing occurrence and distribution of Delphinus delphis in the eastern Aegean Sea (eastern Mediterranean Sea)

Cetaceans are considered bioindicators of the health state of marine ecosystems owing to their wide distribution across the different aquatic ecosystems in the world and their significant top-down control role in the food chain, despite their low biomass. At the same time, effective management of wild cetacean populations severely affected by human pressure requires extensive knowledge on species distribution, habitat use, and associated threats. In this context, defining the factors that directly influence the local occurrence and distribution of cetaceans is one of the underlying challenges and is essential for their conservation and long-term survival. Delphinus delphis sightings data, collected between 2017 and 2021 during 284 standardized vessel-based surveys, were used to set up a presence–absence distribution model in the eastern Aegean Sea, eastern Mediterranean Sea. Binomial generalized additive models with logit as link function were run using the R package mgcv (restricted maximum likelihood method) and different biogeochemical explanatory variables collected from different sources. Longitude, latitude, salinity, chlorophyll a, dissolved ammonium, and dissolved phosphate were selected as non-collinear predictive variables. Through a model validation based on a 10-fold cross-validation approach and a random data splitting procedure of 70%/30% (train/test dataset), a model formula has been selected with an explained deviance of 38.10%, an Akaike information criterion value of 1,661.3, and an area under curve of 0.91. The study confirms that long-term time series of satellite-derived data are useful to assess the occurrence and the spatial distribution of D. delphis, suggesting the need for a better understanding of the influence of these environmental factors especially in the framework of climate changes. Outcomes highlight the need to test further variables and further methods in order to provide increasingly reliable results in view of the conservation measures that must be adopted to stop or reduce the degree of pressure to which these species are subjected

Combining monitoring approaches as a tool to assess the occurrence of the Mediterranean Monk Seal in Samos Island, Greece

With a current global estimation of 600–700 individuals, Monachus monachus is considered among the most threatened seal species globally and is ranked as “Endangered” by the IUCN Red List of Threatened Species. The Mediterranean distribution of the species is fragmented, and the largest known sub-population inhabits its easternmost areas. The present study analyses the occurrence of M. monachus on Samos Island, in the north-eastern Aegean Sea, Greece. From May 2017 to November 2019, data were collected through a combination of monitoring approaches, including visual monitoring from a land position, opportunistic sightings collected by citizen science, and data of stranded individuals. Results indicate the constant occurrence of monk seals in the waters and coastal areas of Samos Island, confirming the importance of this area for conservation purposes. Furthermore, the results show that an integrated methodological approach can contribute to enhancing and increasing data collection, representing an effective method for conservation studies. This approach could be applied in other locations, allowing the scientific community to identify regions of interest, where to expand targeted monitoring and apply conservation measures

Niche overlap between monk seal (Monachus monachus) and small-scale fishery fleet of Marathokampos Bay in Samos Island (North Aegean Sea, Greece)

The Mediterranean population of Mediterranean monk seal (Monachus monachus) is reported as “Critically endangered” by IUCN Red List and its spatial distribution seems to be fragmented in colonies, mainly found around the Ionian and Aegean islands. Monk seals are proved to be highly affected by human pressure such as boat traffic and fishery. Previous studies highlighted the occurrence of net depredation and interactions with artisanal small-scale fisheries. Accordingly, a source of concern is the little quantitative information on various aspects of the Greek small-scale fisheries. Thus, the landings composition of the Marathokampos Bay’s fleet between 2009 and 2011 has been analysed. Then, a dietary overlap index and multivariate analysis were used to analyse the overlap between resources exploited by fisheries and those consumed by monk seals. Results show that for a total of 565 days at sea, 57 % of those fishing days were performed with Trammel nets, 11.3 % with 8- 9 mm Gillnets, 18.4 % with Longline, 12.6 % with Boat seine, 0.5 % with Kalami and 0.2 % for the Purse seine. The total landing biomass of 14.3 tons was composed of 68 species. Monk seal’s diets considered in the analysis showed the highest resource overlap with the Boat seines and the lowest with the Purse seines. Results of the cluster analysis showed that the similarity at 0.2 similarity level revealed a big group composed only by fishing métiers (Longline, Trammel net, Purse seine and total fleet). This study suggests that filling this gap of knowledge could support the implementation of conservation actions. Furthermore, some preliminary results regarding the characteristic of the Marathokampos Bay’s fishing fleet are provided, and the need to gather further data able to better quantify the impacts of both monk seals and fishery on the resources is underlined

Environmental variables influencing occurrence and distribution of Delphinus delphis in the eastern Aegean Sea (eastern Mediterranean Sea)

1. Cetaceans are considered bioindicators of the health state of marine ecosystemsowing to their wide distribution across the different aquatic ecosystems in theworld and their significant top-down control role in the food chain, despite theirlow biomass. At the same time, effective management of wild cetaceanpopulations severely affected by human pressure requires extensive knowledgeon species distribution, habitat use, and associated threats. In this context,defining the factors that directly influence the local occurrence and distribution ofcetaceans is one of the underlying challenges and is essential for theirconservation and long-term survival.2.Delphinus delphissightings data, collected between 2017 and 2021 during284 standardized vessel-based surveys, were used to set up a presence–absencedistribution model in the eastern Aegean Sea, eastern Mediterranean Sea.Binomial generalized additive models with logit as link function were run usingthe R package mgcv (restricted maximum likelihood method) and differentbiogeochemical explanatory variables collected from different sources.3. Longitude, latitude, salinity, chlorophylla, dissolved ammonium, and dissolvedphosphate were selected as non-collinear predictive variables. Through a modelvalidation based on a 10-fold cross-validation approach and a random datasplitting procedure of 70%/30% (train/test dataset), a model formula has beenselected with an explained deviance of 38.10%, an Akaike information criterionvalue of 1,661.3, and an area under curve of 0.91.4. The study confirms that long-term time series of satellite-derived data are usefulto assess the occurrence and the spatial distribution ofD. delphis, suggesting theneed for a better understanding of the influence of these environmental factorsespecially in the framework of climate changes. 5. Outcomes highlight the need to test further variables and further methods inorder to provide increasingly reliable results in view of the conservation measuresthat must be adopted to stop or reduce the degree of pressure to which thesespecies are subjected