Length–weight relationships for six fish species in Iskenderun Bay (Eastern Mediterranean Sea coast of Turkey)

The length–weight relationships (LWRs) were estimated for six non‐indigenous fish species, namely, Apogon smithi (Kotthaus, 1970); Ostorhinchus fasciatus (White, 1790); Pomadasys stridens (Forsskål, 1775); Champsodon capensis Regan, 1908; Torquigener flavimaculosus Hardy & Randall, 1983; and Tylerius spinosissimus (Regan, 1908) from Iskenderun Bay, eastern Mediterranean Sea. Their length–weight relationship b values ranged from 2.902 to 3.501, and all regressions were found to be significant for all six species (P < 0.001). This study is the first reference on length–weight relationships for these six non‐indigenous fish species from the Eastern Mediterranean Sea coast of Turkey.     

Understanding effects of global change on river ecosystems: science to support policy in a changing world

This study explores the past, present and future ecological changes in the highest Mediterranean temporary pond (Omalos pond) in western Crete, Greece. Data from downcore pollen analysis (including pollen and spores from both aquatic vegetation, and terrestrial herbaceous, arboreal and shrub vegetation), modern vegetation monitoring and existing climate scenarios have been combined to provide a picture of the ecological changes in the pond over the last 13,600 years. Downcore pollen analysis throughout the last 13,600 years indicated the presence of species typical of Mediterranean Temporary Pond (MTP) habitats and suggested relatively drier conditions towards the present. The low number of non-native, cultivated species (such as herbaceous Trifolium and Plantago species) observed over this period suggested relatively low impact from crop agriculture, despite the increasing grazing pressure in the area. In the absence of independent proxies, we cannot reliably distinguish between natural and human-induced changes. The presence of aquatic Isoetes in the palaeo-record indicates the existence of an ephemeral pond in the area as early as the beginning of the Holocene suggesting resilience of the ecosystem over time. However, the degraded state of pollen in depths over 55 cm (i.e. 3600 year BP) increases the uncertainty of the interpretation. Currently, the pond holds 76 plant species belonging to 25 families. Therophytes and chamaephytes were the most frequent, suggesting a typical ephemeral habitat life form spectrum. Species richness was found to increase during spring surveys whereas the highest turnover was observed between summer surveys of consecutive years. Cluster analysis demonstrated a distinct zonation in four vegetation belts from the periphery to the centre of the pond which is typical of these environments. Modelling, based on two IPPC scenarios (A2 and B2), predicted relatively low climate change impacts on the pond’s hydroperiod for the next 100 years (i.e. a decrease of 16 and 24 days, respectively). This reduction in the hydroperiod of the pond will have an effect on the physiognomy and spatial extent of vegetation, particularly for the transitional belts between the core and its outer area, while it will exert more pressure on the pond as a water resource for sheep in the region. However, cumulative effects and complex interactions of climate-driven environmental changes and other anthropogenic disturbances might act synergistically to accelerate impacts in the future.     

Allelopathic effects of volatile organic compounds released from Pinus halepensis needles and roots

The Mediterranean region is recognized as a global biodiversity hotspot. However, over the last decades, the cessation of traditional farming in the north part of the Mediterranean basin has given way to strong afforestation leading to occurrence of abandoned agricultural lands colonized by pioneer expansionist species like Pinus halepensis. This pine species is known to synthesize a wide range of secondary metabolites, and previous studies have demonstrated strong allelopathic potentialities of its needle and root leachates. Pinus halepensis is also recognized to release significant amounts of volatile organic compounds (VOC) with potential allelopathic effects that have never been investigated. In this context, the objectives of the present study were to improve our knowledge about the VOC released from P. halepensis needles and roots, determine if these VOC affect the seed germination and root growth of two herbaceous target species (Lactuca sativa and Linum strictum), and evaluate if soil microorganisms modulate the potential allelopathic effects of these VOC. Thirty terpenes were detected from both, needle and root emissions with β‐caryophyllene as the major volatile. Numerous terpenes, such as β‐caryophyllene, δ‐terpinene, or α‐pinene, showed higher headspace concentrations according to the gradient green needles < senescent needles < needle litter. Seed germination and root growth of the two target species were mainly reduced in presence of P. halepensis VOC. In strong contrast with the trend reported with needle leachates in literature, we observed an increasing inhibitory effect of P. halepensis VOC with the progress of needle physiological stages (i.e., green needle < senescent needle < needle litter). Surprisingly, several inhibitory effects observed on filter paper were also found or even amplified when natural soil was used as a substrate, highlighting that soil microorganisms do not necessarily limit the negative effects of VOC released by P. halepensis on herbaceous target species.     

Reproducing under a warming climate: long winter flowering and extended flower longevity in the only Mediterranean and maritime Primula

Under the pressure of global warming, general expectations of species migration and evolution of adaptive traits should always be confirmed with species‐specific studies. Within this framework, some species can be used as study systems to predict possible consequences of global warming also on other relatives. Unlike its mountain congeneric, Primula palinuri Petagn. has endured all the climatic fluctuations since the Pleistocene, while surviving on Mediterranean coastal cliffs. The aim of this work was to investigate the possible evolution of reproductive biological and ecological traits in P. palinuri adaptation to a warmer environment. Data showed that flowering starts in mid‐winter; single flowers remain open for over a month, changing from pendulous to erect. The number of insects visiting flowers of P. palinuri increases during the flowering season, and pollination reduces flower longevity. Overall, the best pollen performances, in terms of viability and germinability, occur at winter temperatures, while pollinator activity prolongs flowering until spring. Moreover, extended longevity of single flowers optimises reproductive success. Both phenotypic plasticity and selective processes might have occurred in P. palinuri. However, we found that reproductive traits of the only Mediterranean Primula remain more associated with cold mountain habitats than warm coastal cliffs. Given the rapid trend of climate warming, migration and new adaptive processes in P. palinuri are unlikely. Response to past climate warming of P. palinuri provides useful indications for future scenarios in other Primula species.     

Diversity patterns and zoogeography of the Northeast Atlantic and Mediterranean shallow-water sponge fauna

Recognizing and understanding present-day biodiversity and biogeographical patterns and how these relate to contemporary and past climate is pivotal to predict the effect of future climate on marine biodiversity and promote adequate conservation policies. Sponges constitute an important and dominant component of the marine benthos and are therefore an excellent model group for such investigations. In this study, we assessed the diversity patterns and the zoogeographical affinities of the Northeast Atlantic and Mediterranean shallow-water demosponge assemblages. Data on the distribution of 745 species throughout 28 areas was compiled from the literature and used to build a presence/absence matrix. Diversity patterns were assessed from estimates of species richness (S) and taxonomic distinctness (AvTD). The Mediterranean Sea proved to be more diverse both in terms of species richness and taxonomic distinctness (S = 539, AvTD = 94.74) than the Northeast Atlantic (S = 480, AvTD = 92.42) and the two regions together were found to constitute a diversity hotspot harbouring approximately 11% of the global demosponge diversity. We found an Atlantic N–S and a Mediterranean NW–SE gradient of increasing taxonomic distinctness that is strongly correlated to both contemporary (R ² = 0.5667; P < 0.01) and historical values (R ² = 0.7287; P < 0.01) of sea surface temperature (SST) at the Last Glacial Maximum (LGM). The zoogeographical affinities examined through classification (cluster analysis) and ordination (non-metric multidimensional scaling, nMDS) based on the Bray–Curtis similarity index, revealed the presence of three groups approximately corresponding to the Northern European Seas, Lusitanian and Mediterranean provinces outlined in the ‘Marine Ecoregions of the World’ (MEOW) classification system. Geographical distance and oceanographic circulation were shown to constitute important factors in shaping the zoogeographical affinities among areas. The vast majority of the species occurring in the Northeast Atlantic and the Mediterranean (67 and 57%, respectively) was shown to have extremely restricted geographical ranges, as single-area or narrow-range (2–3 areas) endemics, which raises some concerns regarding their conservation.     

Diversity and abundance of nematode-trapping fungi from decaying litter in terrestrial, freshwater and mangrove habitats

Nematode-trapping fungi are ubiquitous in terrestrial habitats in dung, soils, litter and woody debris and they also occur in freshwater, but only one species has been found in marine habitats. The purpose of this study was therefore to investigate whether nematode-trapping fungi occurred in mangrove habitats. To achieve this we assessed the diversity of nematode-trapping fungi on decaying litter from mangroves, freshwater and terrestrial habitats (22 sites) in Hong Kong. Composite samples (n = 1,320) of decaying litter (wood and leaves) were examined and a total of 31 species of nematode-trapping fungi belonging to four genera, Arthrobotrys, Monacrosporium, and Dactylella were recorded. Twenty-nine species reported in this study are new records for Hong Kong and 16 species are new records from mangrove habitats worldwide. Nematode trapping fungi are therefore present in marine environments. Commonly encountered taxa were Arthrobotrys oligospora and Monacrosporium thaumasium which are abundant in all habitats. A. oligospora, M. thaumasium and Arthrobotrys musiformis were frequent (F > 10%). Twenty-six species were rare (0.16–9.32%). Species richness and diversity was higher in terrestrial than in freshwater and mangrove habitats (ANOVA, P < 0.001). A higher mean diversity was observed on decaying leaves as compared to decaying wood in all habitats (P < 0.001). Based on Shannon diversity index, it was also observed that taxa characterized by adhesive nets were more frequent in all habitats. This can be explained by the fact that these taxa may have a better competitive saprotrophic ability which would allow them to compete favourably in nutrient limited environments. Abiotic factors that could be linked to differences in species diversity between decaying wood and leaves are also discussed.     

Mediterranean Lithophyllum stictiforme (Corallinales,Rhodophyta) is a genetically diverse species complex: implications for species circumscription,biogeography and conservation of coralligenous habitats

Lithophyllum species in the Mediterranean Sea function as algal bioconstructors, contributing to the formation of biogenic habitats such as coralligenous concretions. In such habitats, thalli of Lithophyllum, consisting of crusts or lamellae with entire or lobed margins, have been variously referred to as either one species, L. stictiforme, or two species, L. stictiforme and L. cabiochiae, in the recent literature. We investigated species diversity and phylogenetic relationships in these algae by sequencing three markers (psbA and rbcL genes, cox2,3 spacer), in conjunction with methods for algorithmic delimitation of species (ABGD and GMYC). Mediterranean subtidal Lithophyllum belong to a well‐supported lineage, hereby called the L. stictiforme complex, which also includes two species described from the Atlantic, L. lobatum and L. searlesii. Our results indicate that the L. stictiforme complex consists of at least 13 species. Among the Mediterranean species, some are widely distributed and span most of the western and central Mediterranean, whereas others appear to be restricted to specific localities. These patterns are interpreted as possibly resulting from allopatric speciation events that took place during the Messinian Salinity Crisis and subsequent glacial periods. A partial rbcL sequence from the lectotype of L. stictiforme unambiguously indicates that this name applies to the most common subtidal Lithophyllum in the central Mediterranean. We agree with recent treatments that considered L. cabiochiae and L. stictiforme conspecific. The diversity of Lithophyllum in Mediterranean coralligenous habitats has been substantially underestimated, and future work on these and other Mediterranean corallines should use identifications based on DNA sequences.     

Comparison of morphological and molecular traits for species identification and taxonomic grouping of oncaeid copepods

The pelagic marine copepod family Oncaeidae is highly diversified (over 100 species worldwide) and includes a great number of sibling species, which are difficult to identify morphologically, because of their very small size (0.18–1.2 mm total length as adults). Global investigations of oncaeid biodiversity are severely hampered by insufficient taxonomic knowledge, in particular for species which have first been described from the European Mediterranean Sea (type locality). Many of these species have been reported as key taxa of small-sized copepod communities in very distant oceanic regions. However, due to the taxonomic uncertainties it cannot be excluded that at least some of these allegedly cosmopolitan species in reality represent a complex of distinct, yet closely related, species. To improve the basis for the identification of Oncaeidae of Mediterranean origin, new diagnostic characters in combination with traditional methods were applied in the present study. Copepods were sampled with fine nets of 0.1 mm mesh size down to a maximum depth of 1,000 m on a west-east-transect in the Mediterranean Sea. Oncaeid species and form variants were predefined morphologically and the genetic identity of the morphospecies was analysed by about 650 and 500 bp region of the mitochondrial COI and 12S srRNA gene sequence, respectively (barcoding). A total of 67 individuals from 24 oncaeid species and forms were successfully analysed, including 12 species and one form of Mediterranean origin. For Oncaeidae, the 12S amplification turned out to be more successful (23 species) than the COI amplification (13 species and 1 form). Together, the morphological and molecular results are discussed with respect to three topics: (1) confirmation of a genetic distinction of three Triconia species, which have been interpreted as sibling species by morphological characters, (2) genetic distance of species within the ovalis-complex of oncaeids and (3) the taxonomic status of two form variants of Oncaea mediterranea (Claus).     

Tempo and mode of the multiple origins of salinity tolerance in a water beetle lineage

Salinity is one of the most important drivers of the distribution, abundance and diversity of organisms. Previous studies on the evolution of saline tolerance have been mainly centred on marine and terrestrial organisms, while lineages inhabiting inland waters remain largely unexplored. This is despite the fact that these systems include a much broader range of salinities, going from freshwater to more than six times the salinity of the sea (i.e. >200 g/L). Here, we study the pattern and timing of the evolution of the tolerance to salinity in an inland aquatic lineage of water beetles (Enochrus species of the subgenus Lumetus, family Hydrophilidae), with the general aim of understanding the mechanisms by which it was achieved. Using a time‐calibrated phylogeny built from five mitochondrial and two nuclear genes and information about the salinity tolerance and geographical distribution of the species, we found that salinity tolerance appeared multiple times associated with periods of global aridification. We found evidence of some accelerated transitions from freshwater directly to high salinities, as reconstructed with extant lineages. This, together with the strong positive correlation found between salinity tolerance and aridity of the habitats in which species are found, suggests that tolerance to salinity may be based on a co‐opted mechanism developed originally for drought resistance.