The link of the Mediterranean Sea to the Indian and Pacific Oceans was artificially created with the opening of the first Suez Canal in 1897, and the second in 2015, allowing the direct passage of marine organisms into the Eastern Mediterranean Sea. About 307 macroalgae (seaweeds) exist in the Israeli Mediterranean shores. The current study lists marine macroalgae within the Levant basin described after the year 1900, with special focus on species from Israeli shores. We identified 86 species for the whole Levant area regarded as exotic, namely, introduced by artificial vectors derived from human activities, including arrivals via the Suez Canal (Lessepsian invasion). Of those 86 species, 42 are Rhodophyta, 23 are Chlorophyta and 21 are Ochrophyta. Further, about 68% are of Indo-Pacific origin, 20% of Atlantic origin, with 12% of the species of uncertain origin. With precaution, we suggest that about 16% of the marine flora in the Israeli Mediterranean shores are of exotic nature. This survey also indicates that about half of the exotic Ochrophyta are of Atlantic origin, while there are no reports of Chlorophyta of Atlantic origin in the Levant basin. Key aspects when evaluating the exotic nature of marine macroalgae are the trustworthiness of past taxonomic identification and long-term records and description of seaweed collections, both particularly troublesome for the Levant basin.
The present work presents a checklist of marine macroalgal species described for the Israeli Mediterranean shores, based on literature records published within the last century. The eastern Mediterranean (Levant Basin) offers a peculiar macro-habitat, which is radically unique within the Mediterranean Sea. The list includes more than 300 species of red (Rhodophyta), brown (Phaeophyta), and green (Chlorophyta) marine macroalgae found primarily in the intertidal zone, with at least one endemic species (Cystoceira rayssiae, Phaeophyta) described for this area.
A taxonomic list of macro marine algae (seaweeds) described in the literature for the Red Sea during the years 1756–2020 is presented. The list was prepared using existing published studies, local monitoring reports, as well as “grey” or unpublished lists of seaweeds for the area. Altogether, we examined more than 300 publications and compiled more than 900 taxonomic names, of which 576 correspond to valid species, whilst 355 names were considered synonyms for these species. The phylum Chlorophyta (green seaweeds) was represented by 37 currently accepted genera and 133 species (including 74 species synonyms). The phylum Ochrophyta (Phaeophyceae only; brown seaweeds) was represented by 52 genera, 157 species and 99 synonyms; and the phylum Rhodophyta (red seaweeds) by 130 genera, 286 species and 182 synonyms. The brown seaweed Sargassum appears to be a particularly biodiverse genus in the area represented by 58 species and 26 synonyms. Our study shows the inconsistency and lack of long-term taxonomic studies and recent molecular investigations of seaweeds from nearly the whole Red Sea.
Pigeon Island, a small nature reserve on the East Mediterranean coast of Israel, is surrounded by abrasion platforms covered with seaweed. The subject of this paper is the community ecology of these macroalgae populations as a function of environmental factors.
Redundancy analysis (RDA) enabled us to rank the measured environmental variables in order of their correlation with vegetation gradients, and to estimate the statistical significance of the correlation by means of Monte Carlo testing. Ordination results showed that most samples line up along a complex gradient corresponding to the transect running from sea front (“front”) to island edge (“inside”). The effect of this gradient was exaggerated by an additional north-south gradient. Hence the most extreme samples were front-north (exposed) and inside-south (sheltered). The first, most exposed, meter of the transect was favored by most of the algal species. Species richness of the front samples was significantly higher than of inside samples. The two most important physical factors were impact of wave activity and distance from seawater. Waves are the source of dissolved CO2, hence the site with the higher wave energy was the most favorable, and showed the strongest competition among plants.
The current study presents an analysis of seaweed communities of Newe Yam, a small island of rocky platforms in the north of Israel. The scope of this research was to evaluate the effect of wave action upon abrasion platforms, including tidal pools and potholes, on the distribution of marine macroalgae species thriving on natural substrates. At the study site there are two major processes operating in opposing directions. One is destruction by natural forces (wave action and chemical and physical constraints) and the other is construction by marine life. The research studies the distribution of algae species as a function of geographical conditions in the examined region. The abiotic environmental habitat conditions include: topography, the width of the abrasion platforms, the presence of potholes and rims, and the orientation of the platform. Concomitantly, the algae community was also studied. This was done along transects perpendicular to the shoreline. The local relationship between various biotic components and the abiotic conditions was also studied. The data were analyzed using the redundancy analysis (RDA) algorithm of Canoco, in order to obtain the level of relative importance and the level of effect of abiotic environmental causes for the spatial distribution of marine flora species. Three systems of environmental factors influence the distribution of algae: orientation, sea versus abrasion-platform conditions, and microhabitat conditions.
In the last two decades, major taxonomic modifications have taken place on marine macroalgae with important changes at the genera level and discovery of cryptic species worldwide. These updates have an important role by serving as a baseline for future ecological interpretations related to on-going climate changes in the marine environment. Hence, this study aimed to elaborate a comprehensive and revised checklist of seaweeds and seagrasses reported in the literature over the years for Syrian Mediterranean Sea shorelines. It was found that the marine flora is quite diverse with a recounted total of 290 species of which 52 are Chlorophyta, 178 Rhodophyta and 60 Ochrophyta (Phaeophyceae). The Syrian shores also host five marine angiosperms (seagrasses), even though Zostera marina Linnaeus has been unaccounted for in recent years. This study will further contribute to a better understanding of seaweed distribution within the Levant basin.