Eastern Mediterranean Ecosystem Research Articles

A host, a parasite, and a predator: the dynamics of successive invasions in the eastern Mediterranean

The eastern Mediterranean shelf ecosystem has been profoundly disrupted by the influx of invasive alien species introduced through the Suez Canal. Yet, the role of retaining or shedding co-evolved parasitofauna in the success of the invading biota has been scarcely monitored, with the exception of the lesser swimming crab Charybdis (Archias) longicollis Leene, 1938 parasitized by the rhizocephalan Heterosaccus dollfusi Boschma, 1960. Host size, sex ratio, prevalence of ovigerous females, parasitization, and multiple parasitization, were studied over 30 years to determine long-term host-parasite variation. Our results reveal that C. longicollis crabs have shifted their temporal activity pattern shortly following the domination of their preferred depth niche by the invasive diurnal predator, the silver-cheeked toadfish Lagocephalus sceleratus (Gmelin, 1789), which preferentially feeds on C. longicollis locally. A unique set of predator-host-parasite interactions among three successive Erythraean invasive aliens is considered herein.

Mesozooplankton production and respiration across a trophic gradient in a coastal Eastern Mediterranean ecosystem

The Inner Saronikos Gulf has served as an area of continuous environmental monitoring for many decades, primarily due to the operation of primary and secondary sewage treatment facilities of the Psyttalia Waste Water Treatment Plant (WWTP). In this groundbreaking study within the region, we conducted measurements of biochemical indices related to respiration (referred to as spETS) and growth (referred to as spAARS) of mesozooplankton. These measurements were then correlated with both biological and environmental data. The ecological quality of the inner Saronikos Gulf was ameliorated moving away from the sewage outfall and thus mesozooplankton sampling encompassed various sites located across a trophic gradient from the WWTP during different seasons (May, September, November 2017, and January 2018). Our observations revealed seasonal variations in both zooplankton abundance and composition, alongside spatial disparities in environmental data. In terms of biochemical data, we observed significant seasonal fluctuations in spETS and R respiration values. Notably, the lowest respiration R value (0.22 mg C m⁻³ d⁻1) was recorded in May, while the highest (4.74 mg C m⁻³ d⁻1) was observed in September. Nevertheless, the variations in spETS and spAARS values among different sites did not demonstrate statistically significant differences. Furthermore, the values of these indices (spETS and spAARS) exhibit a positive correlation with temperature and mesozooplankton biomass at a significance level of 0.01. Lastly, it is noteworthy that phytoplankton production, measured in terms of carbon content (mg C m⁻2), appeared to adequately meet the carbon requirements of the zooplankton throughout all the examined months.

Atlas of phytoplankton phenology indices in selected Eastern Mediterranean marine ecosystems.

Phytoplankton is a fundamental component of marine food webs and play a crucial role in marine ecosystem functioning. The phenology (timing of growth) of these microscopic algae is an important ecological indicator that can be utilized to observe its seasonal dynamics, and assess its response to environmental perturbations. Ocean colour remote sensing is currently the only means of obtaining synoptic estimates of chlorophyll-a (a proxy of phytoplankton biomass) at high temporal and spatial resolution, enabling the calculation of phenology metrics. However, ocean colour observations have acknowledged weaknesses compromising its reliability, while the scarcity of long-term in situ data has impeded the validation of satellite-derived phenology estimates. To address this issue, we compared one of the longest available in situ time series (20 years) of chlorophyll-a concentrations in the Eastern Mediterranean Sea (EMS), along with concurrent remotely-sensed observations. The comparison revealed a marked coherence between the two datasets, indicating the capability of satellite-based measurements in accurately capturing the phytoplankton seasonality and phenology metrics (i.e., timing of initiation, duration, peak and termination) in the studied area. Furthermore, by studying and validating these metrics we constructed a satellite-derived phytoplankton phenology atlas, reporting in detail the seasonal patterns in several sub-regions in coastal and open seas over the EMS. The open waters host higher concentrations from late October to April, with maximum levels recorded during February and lowest during the summer period. The phytoplankton growth over the Northern Aegean Sea appeared to initiate at least a month later than the rest of the EMS (initiating in late November and terminating in late May). The coastal waters and enclosed gulfs (such as Amvrakikos and Maliakos), exhibit a distinct seasonal pattern with consistently higher levels of chlorophyll-a and prolonged growth period compared to the open seas. The proposed phenology atlas represents a useful resource for monitoring phytoplankton growth periods in the EMS, supporting water quality management practices, while enhancing our current comprehension on the relationships between phytoplankton biomass and higher trophic levels (as a food source).

Long-term warming and human-induced plankton shifts at a coastal Eastern Mediterranean site

Plankton are key ecological indicators for assessing the impacts of human-induced pressures like climate change and waste-water discharge. Here, 26 years (1988–2015) of biweekly in-situ chlorophyll-a concentration, mesozooplankton biomass and remotely-sensed sea surface temperature (SST) data are utilized to investigate long-term changes of plankton biomass and timing of growth (phenology) in relation to warming, in a coastal region of the Saronikos Gulf (Aegean Sea). A Waste-Water Treatment Plant (WWTP) was established in 1995, leading to decreased nutrient concentrations circa 2004. Overall, the results indicate an interplay between warming and changes in ecological status. During higher nutrient input (1989–2004), a temporal mismatch between zooplankton and phytoplankton, and a positive zooplankton growth—SST association, are evident. Conversely, in the warmer, less mesotrophic period 2005–2015, an earlier timing of zooplankton growth (related to copepod abundance) synchronizes with phytoplankton growth, including a secondary autumn growth period. Concurrently, an abrupt negative interannual relationship between SST and mesozooplankton, and a summer biomass decrease (linked with cladoceran abundance) are observed. This work provides evidence that current warming could alter plankton abundance and phenology in nearshore Eastern Mediterranean ecosystems, suggesting shifts in plankton community composition that could trigger potential cascading effects on higher trophic levels.

Marine oligotrophication due to fine sediments and nutrient starvation caused by anthropogenic sediment and water retention in large rivers: the Nile damming case

In the last two centuries, human activities have radically reduced the transport of suspended sediment and water to marine systems, mainly in the northern hemisphere, while complete sediment retention has been reported for the Nile River after the construction of the Aswan High Dam (AHD). Here, we focused on changes in the inner-shelf sediments most exposed to the pre-AHD flood plume in the distal part of its littoral cell as a predictor of the ecological response to large river fragmentation. Substantial reductions in fine (15-40%) and increases in coarse (~8 fold) sediment accumulation rates, increases in CaCO3 (~50%), decreases in autochthonous and total organic carbon (OC), and changes in the benthic foraminiferal assemblage toward more OC-sensitive species suggest an enhanced oligotrophication trend. The reduced nutrient fluxes and OC accumulation, and the coarsening of the shelf sediments inhibit the retention of “blue” carbon. Combined with fast climate warming and salinization, river fragmentation may have essential implications for the Eastern Mediterranean ecosystem via benthic oligotrophication processes.

Customizing the Morphological Quality Index (MQI) to evaluate streams in Eastern-Mediterranean ecosystems

Geomorphic assessments are crucial to understanding stream processes, defining ecological stream conditions, and improving management and restoration recommendations. This project presents the first systematic geomorphic assessment of a perennial stream in Israel. The Morphological Quality Index (MQI) protocol was applied in 2017–2018 to test its applicability for Eastern-Mediterranean ecosystems, where heavily regulated streams are common, hydrologic variability is high, and no natural reference streams exist due to long-term anthropogenic pressures. Stream segments were analyzed according to the 25 defined MQI metrics and the protocol was customized for local conditions, characterized by a lack of woody species cover. Results showed that the upstream and downstream segments were in very poor and poor condition, respectively. However, most of the stream was in moderate to good condition, and two segments were rated in very good condition. Reduced functionality was found, especially in longitudinal connectivity of sediment and stream flow, with artificiality found in the most upstream and downstream segments. Riparian vegetation was highly degraded along the entire stream, lacking continuity and providing little functionality or ecological services. Bed substrate analyses indicated a lack of typical downstream fining. Previous flood-management efforts modified channel morphology, and ongoing agricultural pressures prevent lateral stream movement. In addition, water extraction in downstream segments and stream-regulation efforts have greatly reduced water flow and natural depositional processes. Combining all the considered elements, the MQI was found to be a highly suitable tool for evaluating Eastern-Mediterranean perennial streams, with modifications recommended based on local management needs.

Benthic–Pelagic Coupling in the Oligotrophic Eastern Mediterranean: A Synthesis of the HYPOXIA Project Results

Benthic–pelagic coupling studies have shown that the response of the benthic system to eutrophication is subject to complex nonlinear dynamics with specific thresholds beyond which abrupt changes in the response of the ecosystem occur and time lags between inputs and responses. The “HYPOXIA: Benthic–pelagic coupling and regime shifts” project aimed to investigate how nutrient input in the water column results in ecological processes of eutrophication, which may lead to significant, irreversible changes in the eastern Mediterranean marine ecosystems within a short period of time. The project included analysis of historical water and benthic data, field sampling, and mesocosm experiments. From the project results, it can be concluded that nutrient inputs are quickly capitalized by small phytoplankton species in the water column resulting in the bloom of specific species with high nutrient uptake capabilities. When Eutrophic Index values (calculated using nutrient and chlorophyll-a concentrations) cross the moderate-to-poor threshold, the precipitating organic matter can cause observable effects on the benthic system. Depending on eutrophication intensity and persistence, the effects can start from microbenthos, meiofauna, and macrofauna increase in abundance and biomass to significant changes in the community structure. The latter includes the proliferation of macrofaunal opportunistic species, an increase in deposit feeders, and the high risk of ecosystem quality degradation. However, contrary to other regions of the world, no water hypoxia or benthic dead zones were observed as chlorophyll-a and O2 concentrations showed a positive correlation. This is caused by the high photosynthetic activity of the phytoplankton and microphytobenthos, the increased bioturbation of macrofauna, and the increased abundance of sediment deposit-feeding species, which quickly consume the excess organic matter. Eastern Mediterranean coastal ecosystems show high resilience to the adverse effects of eutrophication, preventing hypoxia and azoic conditions when eutrophication is the only source of environmental disturbance.

Customizing the Morphological Quality Index (Mqi) to Evaluate Streams in Eastern-Mediterranean Ecosystems

Customizing the Morphological Quality Index (Mqi) to Evaluate Streams in Eastern-Mediterranean Ecosystems

Seasonal Variations in Litter Layers' Characteristics Control Microbial Respiration and Microbial Carbon Utilization Under Mature Pine, Cedar, and Beech Forest Stands in the Eastern Mediterranean Karstic Ecosystems.

The forest floor is hotspot of several functions integral to the stability of forest ecosystems. However, seasonal variations in litter decomposition rate contribute to biochemical and structural heterogeneity in the forest floor carbon (C) and nutrient cycling. We investigated the influence of seasonal variations in litter layers' micro-climate (temperature and moisture content) and chemical characteristics such as pH, electrical conductivity (EC), total organic C (TOC), total nitrogen (TN), and C/N ratio on microbial respiration, biomass, and C use efficiency under mature (> 80years stage age) pine, beech, and cedar forests in eastern Mediterranean Karstic ecosystems. In contrast to significantly higher microbial respiration in fall, winter, and spring under pine, beech, and cedar forests, the significantly lowest microbial biomass C (MBC) and microbial biomass N (MBN) were observed in winter under each forest. Microbial C use efficiency, measured as the metabolic quotient (qCO2 = CO2/MBC), varied strongly between forest stands and seasons but was generally higher in winter. The significant positive correlations between litter layer and microbial biomass C/N ratios, under beech and cedar forests, suggested strong CN stoichiometric coupling and microbial adaptation to substrate resource stoichiometry. qCO2 correlated significantly negatively with litter layers' temperature, positively with moisture content and EC. However, qCO2 had significant negative relationships with pH in pine and beech forests but significant positive under cedar forest. qCO2 showed significant positive relationships with C/N ratios under all forests but much stronger in beech and cedar forests suggesting higher C respired per unit MBC with an increase in C/N ratio. Despite variations between forest species, the highest MBC/TOC and MBN/TN ratios in fall indicated greater C and N incorporation into microbial biomass. Changes in MBC/MBN ratios under pine (9.62-10.6), beech (8.63-15.6), and cedar (7.32-16.2) forests indicated the shift in microbial communities as fungi have a higher C/N ratio than bacteria. Stepwise regression analysisfurther revealed that microbial respiration and biomass were controlled differentlyby litter layer characteristics in each forest. This study suggested that qCO2 independently or with other microbial indices can show litter layers' controls on organic matter turnover in Karst ecosystems and, taking into account the strong seasonal variations, can enhance the predictive potential of decomposition models.

Microbial respiration, microbial biomass and activity are highly sensitive to forest tree species and seasonal patterns in the Eastern Mediterranean Karst Ecosystems

Soil microbial biomass and functions are the most affected soil components by environmental changes. Therefore, determining the factors affecting soil microorganisms is very important for forest management. This study was conducted to determine the influence of forest type and seasonal variations on microbial biomass and activities in soil. For this, a total of 360 soil samples were collected (120 from each of the Black Pine, Lebanon Cedar, and Oriental Beech) during four seasons of the year in the Eastern Mediterranean Karst Mountain of Taurus, Turkey. Soil samples were used to determine soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (Cmic), microbial biomass nitrogen (Nmic), and microbial respiration (MR). With these data, the metabolic quotient (MR/Cmic ratio) and microbial quotient (qCO2 = Cmic/SOC ratio) were calculated. Soil Cmic and Nmic were significantly higher in Cedar (789.5 ± 438 μg C g−1; 305.26 ± 93 μg N g−1) than in the Beech (691.8 ± 246 μg C g−1; 148.18 ± 43 μg N g−1) and Pine forests (659.4 ± 224 μg C g−1; 130.1 ± 22 μg N g−1). Microbial properties were highly sensitive to forest tree species and seasonal patterns, which can be further used as potential indicators of the effects that forest management practices may have on SOC dynamics. The three forest types showed significant differences in the seasonal Cmic and Nmic patterns, with maximum values occurring in the fall and minimum in the winter season. However, averaged across forest species, SOC did not vary among different seasons. The qCO2 was higher in Cedar forest in the winter season and lower in the Beech forest during the spring season. These findings show that Cedar forest could be more conducive to higher microbial activity and overall soil quality than the Beech and Pine forests.

Sap Flow in Aleppo Pine in Greece in Relation to Sapwood Radial Gradient, Temporal and Climatic Variability

Research Highlights: The radial gradient of sap flux density (Js) and the effects of climatic factors on sap flow of Aleppo pine were assessed at different time scales in an eastern Mediterranean ecosystem to improve our understanding of the species water balance. Background and Objectives: Aleppo pine’s sap flow radial profile and responses to environmental parameters in the eastern Mediterranean were, to our best knowledge, originating to date from more arid planted forests. Information from natural forests in this region was lacking. Our objectives were to (a) determine the species’ radial variability in Js on a diurnal and seasonal basis and under different climatic conditions, (b) scale up to tree sap flow taking into account the radial profile of Js and (c) determine the responses of Aleppo pine’s sap flow over the year to climatic variability. Materials and Methods: Js was monitored in Aleppo pine in a natural forest in northern Greece with Granier’s method using sensors at three sapwood depths (21, 51, and 81 mm) during two periods differing in climatic conditions, particularly in soil water availability. Results: Js was the highest at 21 mm sapwood depth, and it declined with increasing depth. A steeper gradient of Js in deep sapwood was observed under drier conditions. The same patterns of radial variability in Js were maintained throughout the year, but the contribution of inner sapwood to sap flow was the highest in autumn when the lower seasonal Js was recorded in both study periods. Not taking into account the radial gradient of Js in the studied Aleppo pine would result in a c. 20.2–27.7 % overestimation of total sap flow on a sapwood basis (Qs), irrespective of climatic conditions. On a diurnal and seasonal basis, VPD was the strongest determinant of sap flux density, while at a larger temporal scale, the effect of soil water content was evident. At SWC > 20% sap flow responded positively to increasing solar radiation and VPD, indicating the decisive role of water availability in the studied region. Moreover, in drier days with VPD > 0.7 KPa, SWC controlled the variation of sap flow. Conclusions: There is a considerable radial variability in Js of the studied Aleppo pine and a considerable fluctuation of sap flow with environmental dynamics that should be taken into account when addressing the species water balance.

Spatial and temporal dynamics of live fuel moisture content in eastern Mediterranean woodlands are driven by an interaction between climate and community structure

The initiation and spread of wildfires depend, among others, on the live fuel moisture content (LFMC) in plants. Whereas the intrinsic and environmental drivers of LFMC in individual plants are fairly well understood, less is known about ecological interactions potentially affecting LFMC in diverse plant communities. Here, we asked how the interaction between climate and species diversity affects the spatial and temporal dynamics of LFMC in Mediterranean plant communities. We sampled LFMC in six plant communities located along a steep precipitation gradient in four monthly intervals and analysed how LFMC was affected by the structure of the community as well by site and climate conditions. LFMC varied greatly among species, and climate and species richness had an interactive effect on LFMC. On average, species richness had a strong negative effect on LFMC in sites with high rainfall, whereas in drier sites, richness had a small positive effect. Yet the effect of richness on LFMC varied across species, with some exhibiting a positive effect of richness on their LFMC. Individuals surrounded by more heterospecifics tended to have lower LFMC compared with ones surrounded by conspecifics. Our results highlight the interactive roles of climate and community characteristics on LFMC dynamics in eastern Mediterranean ecosystems.

Holocene fish assemblages provide baseline data for the rapidly changing eastern Mediterranean

The eastern Mediterranean marine ecosystem is undergoing massive modification due to biological invasions, overfishing, habitat deterioration, and climate warming. Our ability to quantify these changes is severely hindered by the lack of an appropriate baseline; most ecological datasets date back a few decades only and show already strong signatures of impact. Surficial death assemblages (DAs) offer an alternative data source that provides baseline information on community structure and composition. In this study, we reconstruct the marine fish fauna of the southern shallow Israeli shelf before the opening of the Suez Canal based on fish otoliths. We quantify the age of the otolith DAs by radiocarbon dating, and describe its taxonomic composition, geographic affinity, and trophic structure. Additionally, we test by radiocarbon dating the hypothesis that Bregmaceros, a presumed Lessepsian invader with continuous presence in the Mediterranean throughout the late Cenozoic, is a relict species. The otolith DA dates back to the mid-Holocene because 75% of the dated otoliths of the native species are older than the opening of the Suez Canal in 1869, suggesting that the DA is a proper baseline for quantifying modern impacts. Consistently, 97% of the otoliths and 88% of the species we collected belong to native Mediterranean species. The native anchovy Engraulis encrasicolus dominates the DAs, although gobiids are the most diverse group (14 species, 28%). The DAs show similar trophic structure to present-day pristine Mediterranean coastal fish assemblages. Two non-indigenous species are recorded here for the first time in the Mediterranean Sea, Amblygobius albimaculatus and Callogobius sp., highlighting the importance of DAs for detecting non-indigenous species. Finally, Bregmaceros otoliths are modern, not supporting the previous hypothesis that the taxon is a Pleistocene relict.

Macro-benthic invertebrates associated with the black sponge Sarcotragus foetidus (Porifera) in the Levantine and Aegean Seas, with special emphasis on alien species

The fauna associated to the sponge Sarcotragus foetidus was studied in two eco-regions of the Mediterranean Sea, the Aegean and Levantine Seas. A total of 134 species belonging to 8 taxonomic groups were determined. Different species assemblages were encountered in the eco-regions, mainly due to the importance of some alien species (Red Sea invaders) on sponge communities. Among community parameters, only the number of species differed significantly among the sub-regions. The number of species and the number of individuals were significantly and positively correlated with the sponge volume. The species assemblage patterns determined were significant correlated with a set of environmental variables such as nitrogen, phosphate and dissolved oxygen. Some alien species such as the ophiuroid Ophiactis savignyi and the polychaete Leonnates indicus densely invaded porous systems of sponges in the Levantine Sea, indicating the magnitude of impacts of alien species on the eastern Mediterranean ecosystem. In the Levantine Sea, the alien species accounted for 34% of total number of individuals of macro-invertebrates associated with sponges, but the percentage rose up to 64% in Iskenderun Bay (eastern-most point of studied area). The biotic index ALEX detected a moderate ecological status in the area in terms of the impacts of alien species on native biodiversity.

Fire season modifies the perennial plant community composition through a differential effect on obligate seeders in eastern Mediterranean woodlands

AbstractAimPlant species regenerate after fire either through vegetative growth (i.e., obligate resprouters) or seed germination (i.e., obligate seeders), with some species adopting both strategies (i.e., facultative seeders). Fire season can have important consequences for the relative abundance of plant species adopting these regeneration strategies. The present study aimed to test for differential effects of fire season on perennial plant community composition.LocationEastern Mediterranean woodland in the Judea Mountains, Israel.MethodsWe conducted, for the first time, a large‐scale field experiment, involving prescribed spring and autumn burns in a typical eastern Mediterranean woodland. We sampled the perennial plant community before and after the burns, quantifying temporal changes in community composition caused by seasonal fires.ResultsAlthough fire intensity and severity were consistent between the two seasonal fires, plant community composition differed between areas subjected to spring or autumn burns. The abundances of all common species, Pistacia lenticus (obligate resprouter), Cistus spp. (obligate seeders) and Teucrium divaricatum (facultative seeder), were all reduced by both fires. Yet, their dominance in the post‐fire perennial plant community was retained. Differential fire season effects were detected only among obligate seeders, which experienced a stronger reduction in abundance after spring than after autumn burns.ConclusionsDifferential fire season effects on the perennial plant community resulted from phenological rather than fire intensity/severity effects. Such changes in community composition may have important implications for plant community dynamics, because they affect the circle of “fire event–plant regeneration–fire reoccurrence”, determining the probability and intensity of future fires. Furthermore, even though the eastern mediterranean ecosystem is considered highly resilient to disturbances, increased spatio‐temporal variation in fire season, may result in a new vegetation mosaic, differing from the contemporary one, i.e., an alternative stable state.

Hindcasting the dynamics of an Eastern Mediterranean marine ecosystem under the impacts of multiple stressors

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 580:17-36 (2017) - DOI: https://doi.org/10.3354/meps12271 Hindcasting the dynamics of an Eastern Mediterranean marine ecosystem under the impacts of multiple stressors X. Corrales1,2,*, M. Coll2,3, E. Ofir1, C. Piroddi2, M. Goren4, D. Edelist5, J. J. Heymans6, J. Steenbeek2,3, V. Christensen7, G. Gal1 1Kinneret Limnological Laboratory, Israel Oceanographic & Limnological Research, PO Box 447, 14950 Migdal, Israel 2Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta, n° 37-49, 08003 Barcelona, Spain 3Ecopath International Initiative Research Association, 08003 Barcelona, Spain 4Department of Zoology and The Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv 69978, Israel 5Department of Maritime Civilizations, University of Haifa, Mount Carmel, Haifa 31905, Israel 6Scottish Association for Marine Science, Scottish Marine Institute, Oban PA37 1QA, UK 7University of British Columbia, Institute of Ocean and Fisheries, V6T 1Z4 Vancouver, Canada *‑Corresponding author: corrales@icm.csic.es ABSTRACT: An important challenge for conserving and managing marine ecosystems is to advance our understanding of how multiple human stressors, environmental factors and marine resources interact and influence each other. The ecosystems of the Israeli Mediterranean coast have undergone significant ecological changes in recent decades, caused primarily by the introduction of alien species, fishing and the warming of the waters. Here we used a food-web model representing the continental shelf of the Israeli Mediterranean coast to explore the historical dynamics of the area considering the combined effect of alien species, fishing activities and changes in sea surface temperature and primary productivity. The food-web model was fitted to available time series of data from the early 1990s to 2010 using the temporal dynamic module of the Ecopath with Ecosim modeling approach. An important challenge was to model the numerous alien species inhabiting the Eastern Mediterranean Sea, one of the most invaded marine ecosystems of the world. Historical model simulations satisfactorily matched observed data, especially regarding alien groups. However, lack of data from the pelagic environment limited our ability to compare model output with historical observations. Trophic interactions, climate change and fishing were important factors explaining the historical dynamics of the ecosystem, which showed a degradation pattern over time. Results also highlighted an increasing proportion of alien species in biomass and catch over time, with important effects on the food web. This study represents an important step forward in understanding the changes that are occurring in the Israeli continental shelf ecosystem and the Levantine Sea. KEY WORDS: Eastern Mediterranean Sea · Food-web model · Ecopath with Ecosim · Cumulative impacts · Alien species · Climate change · Fishing impact Full text in pdf format Supplementary material PreviousNextCite this article as: Corrales X, Coll M, Ofir E, Piroddi C and others (2017) Hindcasting the dynamics of an Eastern Mediterranean marine ecosystem under the impacts of multiple stressors. Mar Ecol Prog Ser 580:17-36. https://doi.org/10.3354/meps12271 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 580. Online publication date: September 29, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Long-term changes in surface-active beetle communities in a post-fire successional gradient in Pinus brutia forests

Abstract: Fire is one of the most important ecological factors for many ecosystem types. Since prehistoric times, synergistic effects of fires and humans have led to changes in Eastern Mediterranean ecosystems. The effects of fire on different trophic levels, particularly regarding plants, have been examined intensively in fire-induced ecosystems. In this study, we aimed to study long-term changes in beetle community structure after fire in Pinus brutia Ten. forests. Five sites burned in different years and a control site unburned for at least 50 years were selected. Beetle sampling was conducted using four pit-fall traps in each of four transects in three replication plots at every successional site and in two plots at the control site. Microhabitat variables related to vegetation structure and litter layer were recorded and associated with abundances of beetles and feeding groups. The results showed that total, wood-eating, and predator beetles showed a decreasing trend of abundance along the successional gradient after fire. In contrast to these groups, herbivores tended to increase towards the late successional stages. Middle and late successional stages were important in terms of species richness, species diversity and evenness of beetle communities and feeding groups. The characteristics of vegetation and litter layer changed with successional gradient, playing a decisive role in the structure of beetle communities at successional sites. According to the data presented here, a mosaic structure consisting of different successional stages is very important to sustain high species diversity in beetle communities.

Ancient settlement activities as important sources of nutrients (P, K, S, Zn and Cu) in Eastern Mediterranean ecosystems – The case of biblical Tel Burna, Israel

Human settlement activities are connected with the accumulation of nutrients in archaeological soils. We address the question of whether the large-scale mapping of the elemental composition of the topsoil in contemporary rangeland can be used for the detection of ancient settlement activities.Using portable X-ray fluorescence (pXRF), we mapped the elemental composition of contemporary soils over an area of 67ha in and around the Bronze and Iron Age settlement of Tel Burna (identified as probably corresponding with biblical Libnah).Ancient settlement activities substantially increased concentrations of nutrients (P, K, S, Zn and Cu) in the contemporary topsoil owing to the deposition of biomass ashes and organic wastes. Increased concentrations of elements were detected 2500 years after the site was abandoned and we can therefore suppose that changes in the elemental composition of the soil caused by ancient settlement activities are irreversible on a timescale in which human societies operate. Ancient settlement activities increased concentrations of nutrients in contemporary soil to the same level as recent intensive fertiliser application on an adjacent arable field used for vegetable production. Concentrations of nutrients higher than those on the tell summit were recorded only in recent cattle resting areas with intensive deposition of cattle faeces. Changes in the elemental composition of the soil caused by ancient settlement activities consequently result in differential nutrient availability for contemporary vegetation, affecting ecosystem functions for thousands of years. Using pXRF, large-scale mapping of the elemental composition of the topsoil layer at archaeological sites can help to identify the extent and provide basic information on the character of past human activities in the affected landscape units.

Response of the Eastern Mediterranean Microbial Ecosystem to Dust and Dust Affected by Acid Processing in the Atmosphere

Acid processes in the atmosphere, particularly those caused by anthropogenic acid gases, increase the amount of bioavailable P in dust and hence are predicted to increase microbial biomass and primary productivity when supplied to oceanic surface waters. This is likely to be particularly important in the Eastern Mediterranean Sea (EMS), which is P limited during the winter bloom and N&P co-limited for phytoplankton in summer. However, it is not clear how the acid processes acting on Saharan dust will affect the microbial biomass and primary productivity in the EMS. Here, we carried out bioassay manipulations on EMS surface water on which Saharan dust was added as dust (Z), acid treated dust (ZA), dust plus excess N (ZN) and acid treated dust with excess N (ZNA) during springtime (May 2012) and measured bacterioplankton biomass, metabolic and other relevant chemical and biological parameters. We show that acid treatment of Saharan dust increased the amount of bioavailable P supplied by a factor of ~40 compared to non-acidified dust (18.4 nmoles P mg-1 dust vs. 0.45 nmoles P mg-1 dust, respectively). The increase in chlorophyll, primary and bacterial productivity for treatments Z and ZA were controlled by the amount of N added with the dust while those for treatments ZN and ZNA (in which excessive N was added) were controlled by the amount of P added. These results confirm that the surface waters were N&P co-limited for phytoplankton during springtime. However, total chlorophyll and primary productivity in the acid treated dust additions (ZA and ZNA) were less than predicted from that calculated from the amount of the potentially limiting nutrient added. This biological inhibition was interpreted as being due to labile trace metals being added with the acidified dust. A probable cause for this biological inhibition was the addition of dissolved Al, which forms potentially toxic Al nanoparticles when added to seawater. Thus, the effect of anthropogenic acid processes in the atmosphere, while increasing the flux of bioavailable P from dust to the surface ocean, may also add toxic trace metals such as Al, which moderate the fertilizing effect of the added nutrients.

Vegetation cover and species richness after recurrent forest fires in the Eastern Mediterranean ecosystem of Mount Carmel, Israel

Fire is a common disturbance in Mediterranean ecosystems, and can have a destructive, influential, and even essential, effect on vegetation and wildlife. In recent decades there has been a general increase in the number of fires in the Mediterranean Basin, including in Mount Carmel, Israel. The effects of recurrent forest fires on vegetation cover and species richness were determined in the spring of 2009 and 2010 by field surveys. The results of this study showed that the vegetation cover changes after recurrent forest fires, and can serve as a good indicator of the influence of fire and the resulting ecosystem rehabilitation. The dominant cover in most fire-damaged areas was composed of shrubs and dwarf-shrubs, especially Cistus salviifolius and Calicotome villosa. Tree cover was severely damaged after recurrent fires, and in those areas there was a drastic decrease of the total plant cover. Species richness increased mainly in the first decade after the recurrent fires, and decreased when the forest canopy began to close. Fire recurrence with short intervals (4–6years) between fires may lower the rehabilitated processes of the ecosystem and change its equilibrium.