Kavala Gulf Research Articles

Effects of flooding on the Mediterranean Cymodocea nodosa population in relation to environmental degradation

Abstract Cymodocea nodosa is a common seagrass species of shallow and sheltered Mediterranean waters, where extreme flushing of plumes can occur during excessive rainfall. Cymodocea nodosa shoots were sampled from two habitats of Kavala Gulf, one nearly pristine (less stressed, Vrasidas) and another highly stressed (Nea Karvali), to study if flooding might negatively affect seagrass habitats. Photosynthetic performance of shoots from the pristine habitat acclimated better than shoots from highly stressed conditions simulating a flooding event. Indeed, a significant (p < 0.01) interaction between habitat and flooding on photochemical energy harvesting (ΔF/Fm′) values was found, with lower ΔF/F m′ values in the pristine habitat under control conditions. Furthermore, based on relative electron transport rate (rETR) curves reconstructed from fluorescence-versus-irradiance data, shoots from the pristine habitat performed better after 18 days of treatment to flooding. On the other hand, shoots from highly stressed habitats grew faster than pristine ones, but their growth decreased similarly under flooding conditions. The implications for management and conservation priorities for this phenotypically plastic seagrass in the Mediterranean are discussed.

Effects of photoperiod and temperature on ecophysiological responses of Ericaria barbatula (Phaeophyceae): a long-term study

Abstract The photoperiod alone or in combination with temperature may affect macroalgal growth, reproduction, and development. This study aimed to investigate the responses of Ericaria barbatula, a perennial fucalean species collected from Kavala Gulf, Greece, to photoperiod and temperature. Maximum quantum yield (F v /F m ), wet biomass (g), relative growth rate (day−1), and reproduction (receptacles and zygote formation) were monitored in two laboratory experiments, the first one in two consecutive phases (A and B), that lasted at least seven months. While in Experiment 1, phase A, specimens were cultivated under long-day (LD) and short-day (SD) conditions at a constant temperature, in Experiment 1, phase B, they were cultivated at a seasonally changing temperature. The results indicated that E. barbatula reproduced in both phases under SD conditions and grew better in winter to early spring under seasonally changing temperatures. The cultivation under night-break (NB) daylength and seasonally changing temperatures (Experiment 2) indicated that E. barbatula is a facultative (quantitative) SD plant, a result that needs further examination. However, the induction of reproductive organs under SD conditions has been confirmed. It secures the release of zygotes and the germlings’ growth in the field from April to June/July under non-stressful Mediterranean Sea temperatures.

Diversity and composition of algal epiphytes on the Mediterranean seagrass Cymodocea nodosa: a scale-based study

Abstract 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.

A Methodology for the Estimation of Microplastic Concentration in Relation to the Meteorological Forcing and WWTPs Effluents in Urban Coastal Areas

The study of the urban coastline is of great significance for understanding the impacts of human activities on the marine environment. Only recently the emission of microplastics is starting to be considered as a threat to aquatic and terrestrial ecosystems and currently, little information on this topic is available. The present study focuses on the development of a methodology based on the implementation of the hydrodynamic circulation model ELCOM (Estuary and Lake Computer Model) for the estimation of microplastics distribution in Kavala Gulf coastline. The approach aims to include the effects of the high seasonal touristic activity and consequent large fluctuations in wastewater treatment plants (WWTPs) discharge rates. Parameters such as microplastic concentration, effluent flow rate and temperature, meteorological forcing and scalars at the boundaries were applied and the simulation was designed to cover the entire 2006 in order to include an approximation of the seasonal 3D dispersion patterns. The microplastic concentration was estimated based on the suspended particulate matter (SPM) concentration measurements applying the approach of [1]. The physical and chemical parameters of the particles were assumed to conform with the assumptions of [2]. The results showed a strong correlation between the microplastics dispersion patterns, the wind climate and the seasonal increase in population during the summer. Microplastic concentrations reached up to 0.185 μg/l in the WWTPs adjacent coastline in correspondence to the beaches with the highest touristic activity. The periodical formation of anticyclonic flows resulted in a net transport towards the center of the gulf and an increase in microplastic concentration in the bottom layer. On the other hand, the simulation showed that considerable quantities of microplastics tend to be transported outside the study area and far from the coastline in deeper waters.

Summer mesozooplankton assemblages in relation to environmental parameters in Kavala Gulf, northern Aegean Sea

Shallow coastal areas are ecosystems with high productivity. Although the eastern part of the Mediterranean Sea is oligotrophic, the shallow coastal waters of the northern Aegean, such as Kavala Gulf, are productive due to the influence of the Black Sea water and the presence of freshwater input from three rivers. The aim of this work was to determine the structure of zooplankton communities in Kavala Gulf in the summer of 2002 and 2003 and to investigate their relation to environmental variables. Zooplankton communities were characterized by the presence of common coastal Cladocera, such as Penilia avirostris, small pelagic Copepoda, such as the calanoida Acartia clausi and the cyclopoida Oithona plumifera, and Tunicata, such as Oikopleura, Fritillaria and Doliolidae. The abundances corresponded to the peak of the warm period and were significantly greater in 2002 because of a P. avirostris bloom, which seemed to have better exploited the environmental sources favouring its dominance in the area. Overall, the structure of summer mesozooplankton communities in Kavala Gulf follows the pattern exhibited by mesozooplankton communities in other Greek coastal areas of the northern Aegean Sea.

An integrated coastal zone observatory at municipal level: the case of Kavala Municipality, NE Greece

The Integrated Coastal Zone Management (ICZM) Observatory of Kavala Municipality has been developed during the Mare Nostrum Project following the well-known DPSIR concept (Drivers, Pressures, States, Impacts and Responses). The Observatory aims to aid the day-to-day operations of the Municipality, collecting, analyzing and processing historic, present and forecasted environmental, socio-economic and legal-institutional ICZM datasets collected from a variety of sources. Data are presented in a series of well-structured layers imported in a Geographic Information System (GIS) web-environment, to aid decision-makers at Municipal, Regional and National level to formulate policies on ICZM matters; to provide reliable datasets to scientists and engineers; to engage active citizens and the broader public into coastal zone issues; to promote the distribution of information among coastal managers, stakeholders and the general public. Static datasets as topographic, bathymetric, geologic and other base maps, urban and rural planning maps, local municipal acts, public networks and locations of public interest were digitized and embedded in the system. Historic environmental data together with dynamic data produced daily by a series of coupled operational models (meteorological, hydrologic, hydrodynamic, wave and eutrophication) and climate change datasets were also included. The legal-institutional framework of the coastline and the interactive tools to enhance public participation represent novel elements of the herein presented ICZM Observatory. The Kavala Gulf mussel farmers, the local Port Authority and the decision-makers on siting hydroplane landing-zones are the main user groups of the ICZM Observatory.

Atmospheric Emissions from Oil and Gas Extraction and Production in Greece

This paper addresses the atmospheric emissions of CO2, SO2, H2S, NOx, and volatile organic compounds (VOCs) from oil and gas extraction and production in the Gulf of Kavala. This is currently the only location of oil and gas production in Greece. Facilities are located both offshore (Kappa and Delta platforms) and onshore (Sigma plant), producing sweet gas, sour gas, and sour crude oil. This study presents the characteristics of atmospheric emissions, including emission measurements, emission inventories, and concentration measurements, from a central monitoring station and twelve total sulfation stations, the latter aiming to assess the effects of atmospheric emissions to air quality. During the development of the monitoring system, special attention was placed to sulfur compounds, since the existence of sour gas and sour crude oil was expected to lead to increased amounts of H2S and SO2. One of the main findings of the present study is that if the prevailing wind direction is considered (i.e., from N–NE), then the central monitoring station is not located downwind of the onshore and offshore facilities; therefore, its position should be re-examined. The emission inventories showed that flaring at the offshore facilities is the main source of SO2 emissions, while SO2 emissions and ambient concentrations were well below the relevant standards. Furthermore, CO2 emissions were lower by 67.73% as compared to 2008, when emissions reached a maximum. This was attributed to more energy demanding activities during that period, and mainly to the operation of turbines between 2007 and 2009. Since it is expected that the exploitation of hydrocarbons as well as oil and gas extraction and production will increase in the future in Greece, appropriate measures should be taken to ensure environmental protection, such as the use of up-to-date emission control technologies and a flare gas recovery system.

Assessment of Urban Pollution Footprint in a Typical Mediterranean Semi-Enclosed Gulf

This work assesses the changes, the causes and the impact of pollutant loads from treated wastewater in a typical Mediterranean coastal water body. Focusing on wastewater treatment and industrial plants, assessment is based on the analysis of systematic pollution indicators, such as the carbonaceous material, suspended solids and nutrients for the period 2009–2012. It occurs that Kavala Gulf receives annually approximately 5 million m3 from point sources. Organic matter, ammonia, nitrate and nitrite, and phosphorus annual loads increased sharply in 2012 to 130, 13, 8 and 12 tons, respectively, due to wastewater treatment technical inefficiencies. Additional nitrogen (390 tons) and phosphorus (53 tons) annual discharges from a phosphoric fertilizer plant raise significantly the inorganic pollution levels in the study area, causing frequent eutrophication incidents. Reduction of discharged volumes could be achieved through wastewater reclamation and reuse, either covering internal wastewater treatment plant requirements and/or watering urban and suburban green areas and groves and forests, cleaning streets, supplying water to firefighting systems, and irrigating agricultural and peri-urban landscape.

Cymodocea nodosa metrics as bioindicators of anthropogenic stress in N. Aegean, Greek coastal waters

Anthropogenic derived stressors are known to affect seagrasses. Cymodocea nodosa, a widespread seagrass in the Mediterranean Sea with high phenotypic plasticity, is known to acclimatize rapidly to prevailing environmental conditions. To use this species in the biomonitoring of anthropogenic stress, physiological (effective quantum yield of photosystem II [ΔF/Fm′], maximum quantum yield [Fv/Fm], and maximum fluorescence [Fm]), phenological (leaf length and width, number of leaves per shoot), and biochemical (Chl-a, and Carbon, Nitrogen, Phosphorus contents of leaves) metrics were measured between two meadows under different levels of anthropogenic influence in the Kavala Gulf, North Aegean Sea. To reduce bias and separate seasonality from anthropogenic stress responses the physiological parameters were measured under constant laboratory conditions and a hierarchical sampling design was employed. Two well-described meadows, one pristine (Brasidas) and one under significant anthropogenic stress (Nea Karvali), were sampled on six occasions between June 2007 and March 2009 at three spatial scales ranging from hundreds of meters (area) to kilometer (site) to 10s of kilometers (meadow). Of the twelve metrics measured, N-content and Fm were the most effective at discriminating between the two C. nodosa meadows and, therefore, should be considered as promising bioindicators. Statistically significant differences were identified between the cold and hot periods for almost all metrics measured, suggesting that seasonality is a key driver of the observed responses.

Sympatric Clupeoid Fish Larvae in the Northeastern Mediterranean: Coexistence or Avoidance?

The summer (July 2002 and 2003) larval concentrations of two commercially important clupeoid species (order: Clupeiformes), the European anchovy (Engraulis encrasicolus) and round sardinella (Sardinella aurita), were measured in Kavala Gulf (northern Aegean Sea), in order to examine their distribution patterns. Anchovy was generally most abundant, reaching 13 852 larvae 10 m−2 in 2003 and occurred in more stations compared to round sardinella. Despite the spawning of both species occurring across the entire gulf, the general spatial distribution of their larvae was different, with European anchovy larvae occupying the entire gulf and round sardinella larvae mainly concentrated at offshore stations. The reason proposed for the spatial segregation of their larvae is direct competition for resources. Yet, coexistence of the two species was observed in frontal areas with abundant food resources that prevent competition.

Clastic sedimentary features of beachrocks and their palaeo-environmental significance: comparison of past and modern coastal regimes

Clastic sedimentary features of beachrocks and unconsolidated deposits of parent beaches were investigated along the northern Aegean coastline (Greece) to assess their suitability in palaeo-environmental reconstruction. Twelve paired datasets were collected in the Thermaikos, Toroneos, Siggitikos and Ierissos gulfs of the Chalkidiki Peninsula, the adjoining Kavala Gulf and Thassos Island, comprising beachrock cores and companion beach subsurface sediments. Particle size analyses based on univariate and bivariate statistics suggest that, during the time period of beachrock formation, depositional conditions differed distinctly from those of the modern parent beaches. The results imply difference of maturity level of beach evolution from the time of cementation (coarser materials-early stage of beach formation) to modern situation (finer materials-reworked and ‘mature’ beach sediments). Furthermore, the findings indicate increasing coastal protection due to beachrock exposure in the modern swash zone. In conclusion, it is suggested that textural analysis of beachrocks in comparison with unconsolidated sediments of the parent beach might provide information regarding differences of coastal depositional regimes and future research could focus on specific-layer analysis and comparison.

Assessment of Trace Metals Contamination in the Suspended Matter and Sediments of a Semi-enclosed Mediterranean Gulf

This study investigates the distribution of heavy metals in the suspended particulate matter and the sediments of Kavala Gulf, located in Northern Greece. Particulate trace metals were determined in accordance to water column physicochemical parameters. Metals in sediments were related to the textural characteristics, the organic matter, and carbonate contents of surficial sediments. Results illustrated that the diverse human coastal activities influence the distribution of particulate and sediment metal concentrations, since lower trace metal levels were detected along the western (tourism) and eastern (aquaculture) coast, while increased values were observed at the central (urban and industrial). Overall, particulate metals show moderately low levels compared to other similar sites, with the exception of Ni and Cd depicting local peaks along the industrial coastal zone. Significantly increased levels for particulate lead (123.1 μg/g) and chromium (113.9 μg/g) were detected at the sites near the industrial zone. Direct effluents from a fertilizer plant appeared responsible for the increased Pb, Cr, and Cd levels, while the increased values in Zn, Cu, and Hg appear related to phosphogypsum leaching. Sediment contamination assessment indicated that the Kavala Gulf is characterized by clean to marginally polluted sediments, with moderately severe pollution levels along the urban coastline.

Restriction Fragment Length Analysis of the Cytochrome b Gene and Muscle Fatty Acid Composition Differentiate the Cryptic Flatfish Species Solea solea and Solea aegyptiaca

Overlapping external morphometric characters easily confound the flatfishes Solea aegyptiaca and Solea solea (Soleidae) in areas of the Mediterranean Sea where both species live in sympatry. This leads to uncertainties in the fisheries and marketing of the species, in addition to misinterpretations in biogeography and conservation studies. This paper describes a simple restriction fragment length-based diagnostic test that differentiates S. solea from S. aegyptiaca, as well as from other species of the Soleidae family. Furthermore, the two species living in sympatry in the Gulf of Kavala (North Aegean Sea, Greece) present significant qualitative differences in muscle fatty acid composition, a property that can also be used to distinguish the two cryptic species.

Modeling the Nestos River plume dynamics using ELCOM

Results from the first attempt to simulate the Nestos River plume using the three-dimensional nu merical model ELCOM are presented. The numerical model was validated using in-situ CTD data from three field campaigns taking place under variable discharge and meteorologic conditions. Results showed that the model predicted satisfactorily the surface expansion and the shape of Nestos river plume in all cases. The calculated versus observed salinity values showed significant correlations under high, moderate-high and low flow condition. The numerical model revealed that Nestos plume enters the Kavala Gulf only under high and intermediate river flow conditions, and only under favorable east and northeast winds. After validation, the model was used to examine plume behavior under four test cases of variable discharge and winds. These results illustrated that Nestos plume is mostly wind-driven, while river discharge is the key parameter responsible for transporting the plume away from the mouth. The plume directed mainly westwards throughout the year, under the influence of the general water circulation and the predominance of E–NE winds. Local coastal morphology such as the existence of the Thassos Passage also plays a significant role on the plume dispersion and movement.

Assembly processes in upper subtidal macroalgae: The effect of wave exposure

The structure and diversity of sixteen macroalgal assemblages originating from two coastal locations in the Northern (Kavala gulf) and Central (Maliakos gulf) Aegean in Greece were explored by examining their relative abundance distributions (RADs) and fitting five stochastic niche-based models. A mechanistic interpretation of the underpinning assembly processes was attempted by relating the assumptions of the fitted models with available abiotic data corresponding to each assemblage. The random fraction niche-based model, assuming a random niche apportionment to species, was fitted to the majority of Maliakos assemblages characterized by more evenly distributed and speciose RADs, whereas the random assortment model, assuming no relationship among species abundance and niche size, was fitted to most of the Kavala assemblages characterized by steeper RADs with fewer species. Among the possible underlying mechanisms, wave exposure seems to play a key role in macroalgal assembly processes; however factors such as biogeography and hard substrate availability must be also taken into consideration. Short-term processes as changes in resource availability (nutrients and light), known as drivers of assembly rules in other primary producers (e.g. phytoplankton), do not considerably affect macroalgae in the oligotrophic Eastern Mediterranean, possibly due to their longer life spans.

Size distribution approaches for monitoring and conservation of coastal Cymodocea habitats

Abstract Cymodocea nodosa's leaf length distribution was studied as an easily measurable indicator to monitor and conserve Macedonian, North Aegean, Greek coastal habitats. Three Cymodocea meadows off the eastern Kavala Gulf coast (Nea Karvali, Erateino, Agiasma), with that of Nea Karvali close to an industrial area being the most degraded, were sampled during the seagrass main growing season in July 2004. Two further meadows, one pristine to less degraded (Brasidas, Gulf of Kavala) and one degraded (Biamyl, Inner Thessaloniki Gulf), were sampled as benchmarks in July 2005. The results were evaluated using Gaussian fit curves, and non‐parametric and nested parametric ANOVA on a hierarchy of spatial scales: area (tens of metres), site (hundreds of metres) and meadow (kilometres). Frequency (%) distribution of leaf length values and CymoSkew index variation were best associated with anthropogenic stress. Frequency (%) distribution of adult and intermediate photosynthetic leaf length values revealed a unimodal distribution possible to be fitted, at least at pristine to less degraded meadows, by normal distribution (R2>0.5). Statistically significant variation was estimated for CymoSkew index, a quantitative expression of leaf length asymmetry, on the meadow scale (P<0.001). Biamyl (3.82) and Nea Karvali (3.64) were indicated as heavily degraded meadows, Erateino (2.93) as a degraded meadow, Agiasma (2.18) as a meadow with the first signs of degradation, and Brasidas (1.68) as a pristine to less degraded meadow. These results in combination with other meadow specific biotic parameters were used to suggest a preliminary angiosperm ‘Ecological Status Classes’ classification scheme useful for the implementation of WFD in the north Aegean Sea. The CymoSkew index seems to respond to lower levels of stress than is needed for other more conservative plant modules and therefore, could be regarded as an early warning indicator of Cymodocea habitat degradation. Copyright © 2009 John Wiley & Sons, Ltd.

Summer distribution of fish larvae in northern Aegean Sea

Larval fish and hydrographic data were collected in Kavala Gulf (northern Aegean Sea) across a fine scale grid of 17 stations in two surveys, carried out in the beginning of July 2002 and 2003. Despite the different taxonomic resolution and excluding the unidentified larvae, 22 taxa were caught in 2002 and 27 in 2003. Seventeen taxa were present in both years' collections. A total of 833 larvae were collected during the two samplings. The adults of several larvae caught, although sometimes at very low concentrations, are species with high commercial value or represent a major proportion of the captured production of the northern Aegean Sea. The larvae of European anchovy (Engraulis encrasicolus) were most abundant in both years followed by the brown comber (Serranus hepatus), the gobies (Gobius sp.) and, only for 2003, round sardinella (Sardinella aurita). Maximum anchovy larval densities reached 4145/10 m2 and 13852/10 m2 in the 2002 and 2003 surveys, respectively. The spatial extent of anchovy larvae was also high as they were collected at 12 stations in 2002 and at 15 in 2003. Besides water circulation, the spatial distribution of fish larvae was largely influenced by temperature, salinity and dissolved oxygen.

Body size descriptor of Cymodocea nodosa indicates anthropogenic stress in coastal ecosystems

1 - We studied skewness (asymmetry) of log-transformed relative frequencies of Cymodocea nodosa leaf length (SkLnRfLL) as an easily measurable indicator of anthropogenic stress in selected biotopes of Eastern Macedonia, North Aegean, Greece. 2 - Since the spatial variation of the skewness coefficient was not known, a random nested sampling design within a hierarchy of spatial scales ranging from 10’s of metres (area) to 100’s of metres (site) to kilometres (biotope) was implemented. Three Cymodocea nodosa biotopes of the eastern Kavala Gulf coasts (Nea Karvali, Erateino, Agiasma), with that of Nea Karvali being the most degraded (close to an industrial area), were sampled during the main seagrass growth season in July 2004. Fifty five quantitative samples with 60 or more Cymodocea leaves were analysed in total, using non-parametric and parametric nested ANOVA. 3 - Statistically significant variation (p<0.01) was observed at the biotope scale, showing maximum mean value in the most degraded biotope of Nea Karvali (3.7) and minimum mean values in the less impacted biotopes of Agiasma (2.3) and Erateino (2.7). This pattern was also confirmed by post-hoc comparison. 4 - SkLnRfLL, based on the theory of normal population distribution and metabolic theory of ecology, seems to be a promising indicator of anthropogenic stress in North Aegean coastal ecosystems.

Sediment and Suspended Matter Lead Contamination in the Gulf of Kavala, Greece

Sediment and suspended particulate matter samples from 24 stations in the Gulf of Kavala have been examined for lead contamination. Grain size analysis and organic matter content were also performed. Total -- anthropogenic sediment lead concentrations and enrichment factors at stations close to harbors and chemical industries were found higher (up to 209-135 micro g/g and 4.12 respectively), in relation to concentrations from the rest of the coastal zone. In the above areas, increased suspended particulate lead in the bottom of the water column was also recorded (up to 109 micro g/g). Total sediment lead concentrations composed of high natural Pb background increased with decreasing grain size, suggesting their association with the fine fractions of the sediments (31.1-66.0% mud presence) and the organic matter content (6-9% higher values). Overall, higher total lead concentrations in the sediments, determined by this work, appear to be significantly different from those reported for the Gulf of Kavala in previous studies and similar to those detected in other highly contaminated eastern Mediterranean coastal areas.

Monitoring Water Quality and Assessment of Land-Based Nutrient Loadings and Cycling in Kavala Gulf

The results of a systematic and intensive nutrient monitoring program are reported, which took place during the period 1997-1999 in Kavala Gulf, Northern Greece, having as a general task to study the impact of the various human activities on the nutrient loadings and cycling of the aquatic environment. A nutrient budget box model was used to estimate the annual capacity of Kavala Gulf to store and transform dissolved inorganic nitrogen and phosphorus, aiming at understanding the biogeochemical processes taking place in the area of interest. Point sources of nutrients from two municipal wastewater treatment plants (Kavala and Palio Seawage Treatment Works) and a phosphoric fertilizer producing industrial facility (PFP), as well as non-point sources from agricultural activities, seem responsible for the increased concentrations of dissolved inorganic nitrogen and phosphorus. Seasonal N:P-ratios suggest that nitrogen is the limiting nutrient during the summer, autumn and winter and phosphorus during the spring. The annual nutrient budget model revealed that Kavala Gulf is presently slightly autotrophic with nitrogen fixation exceeding denitrification.