Ali M. Al-Aidaroos

Zooplankton diversity across three Red Sea reefs using pyrosequencing

Coral reefs are considered among the most diverse ecosystems on Earth, yet little is known about the diversity of plankton in the surrounding water column. Moreover, few studies have utilised genomic methods to investigate zooplankton diversity in any habitat. This study investigated the diversity of taxa by sampling 45 stations around three reef systems in the central/southern Red Sea. The diversity of metazoan plankton was investigated by targeting the 18S rRNA gene and clustering OTUs at 97% sequence similarity. A total of 754 and 854 metazoan OTUs were observed in the data set for the 1380F and 1389F primer sets respectively. The phylum Arthropoda dominated both primer sets accounting for ~60% of reads followed by Cnidaria (~ 20%). Only about 20% of OTUs were shared between all three reef systems and the relation between geographic distance and Jaccard Similarity measures was not significant. Cluster analysis showed that there was no distinct split between reefs and stations from different reefs clustered together both for metazoans as a whole and for the phyla Arthropoda, Cnidaria and Chordata separately. This suggests that distance may not be a determining factor in the taxonomic composition of stations.

Larval development of the land hermit crab Coenobita scaevola (Forskål, 1775) (Crustacea: Anomura: Coenobitidae) reared in the laboratory

The complete larval development of Coenobita scaevola (Forskal, 1775) is described, based on laboratory rearing. An ovigerous female was collected on 17 April 1987 from Jeddah, Saudi Arabia. The species has 7 zoeal stages and a megalopa, and development to the megalopa took 47 days at 25°C and salinity 38–39 ppt. The larvae show a number of small differences from C. rugosus, from Japan, but show greater differences compared with C. clypeatus, from the Caribbean. A central telson process in the later zoeal stages appears to be a character of the Coenobitidae.

Molecular biodiversity of Red Sea demosponges

Sponges are important constituents of coral reef ecosystems, including those around the Arabian Peninsula. Despite their importance, our knowledge on demosponge diversity in this area is insufficient to recognize, for example, faunal changes caused by anthropogenic disturbances. We here report the first assessment of demosponge molecular biodiversity from Arabia, with focus on the Saudi Arabian Red Sea, based on mitochondrial and nuclear ribosomal molecular markers gathered in the framework of the Sponge Barcoding Project. We use a rapid molecular screening approach on Arabian demosponge collections and analyze results in comparison against published material in terms of biodiversity. We use a variable region of 28S rDNA, applied for the first time in the assessment of demosponge molecular diversity. Our data constitutes a solid foundation for a future more comprehensive understanding of sponge biodiversity of the Red Sea and adjacent waters.

High Mortality of Red Sea Zooplankton under Ambient Solar Radiation

High solar radiation along with extreme transparency leads to high penetration of solar radiation in the Red Sea, potentially harmful to biota inhabiting the upper water column, including zooplankton. Here we show, based on experimental assessments of solar radiation dose-mortality curves on eight common taxa, the mortality of zooplankton in the oligotrophic waters of the Red Sea to increase steeply with ambient levels of solar radiation in the Red Sea. Responses curves linking solar radiation doses with zooplankton mortality were evaluated by exposing organisms, enclosed in quartz bottles, allowing all the wavelengths of solar radiation to penetrate, to five different levels of ambient solar radiation (100%, 21.6%, 7.2%, 3.2% and 0% of solar radiation). The maximum mortality rates under ambient solar radiation levels averaged (±standard error of the mean, SEM) 18.4±5.8% h−1, five-fold greater than the average mortality in the dark for the eight taxa tested. The UV-B radiation required for mortality rates to reach ½of maximum values averaged (±SEM) 12±5.6 h−1% of incident UVB radiation, equivalent to the UV-B dose at 19.2±2.7 m depth in open coastal Red Sea waters. These results confirm that Red Sea zooplankton are highly vulnerable to ambient solar radiation, as a consequence of the combination of high incident radiation and high water transparency allowing deep penetration of damaging UV-B radiation. These results provide evidence of the significance of ambient solar radiation levels as a stressor of marine zooplankton communities in tropical, oligotrophic waters. Because the oligotrophic ocean extends across 70% of the ocean surface, solar radiation can be a globally-significant stressor for the ocean ecosystem, by constraining zooplankton use of the upper levels of the water column and, therefore, the efficiency of food transfer up the food web in the oligotrophic ocean.

A COLLECTION OF CALLIANASSIDEA DANA, 1852 (DECAPODA, PLEOCYEMATA) FROM THE SAUDI ARABIAN RED SEA COAST WITH A CHECK-LIST OF ALL GHOST SHRIMPS (THALASSINIDEA AND CALLIANASSIDEA) KNOWN FROM THE AREA

During a survey of the coastal biodiversity of the Saudi Arabian Red Sea, four species of callianassid ghost shrimps were collected: Gilvossius bouvieri (Nobili, 1904), Neocallichirus mucronatus (Strahl, 1862a), Podocallichirus madagassus (Lenz & Richters, 1880), and Callianidea typa H. Milne Edwards, 1837. Of these, N. mucronatus is recorded from the Red Sea for the first time. With this new record, 29 species of the group are now known in the Red Sea fauna. The distribution of the species within the Red Sea is discussed in detail.

Latitudinal environmental gradients and diel variability influence abundance and community structure of Chaetognatha in Red Sea coral reefs

The Red Sea has been recognized as a unique region to study the effects of ecohydrographic gradients at a basin-wide scale. Its gradient of temperature and salinity relates to the Indian Ocean monsoon and associated wind-driven transport of fertile and plankton-rich water in winter from the Gulf of Aden into the Red Sea. Subsequent evaporation and thermohaline circulation increase the salinity and decrease water temperatures toward the North. Compared with other ocean systems, however, relatively little is known about the zooplankton biodiversity of the Red Sea and how this relates to Red Sea latitudinal gradients. Among the most abundant zooplankton taxa are Chaetognatha, which play an important role as secondary consumers in most marine food webs. Since Chaetognatha are sensitive to changes in temperature and salinity, we surmised latitudinal changes in their biodiversity, community structure and diel variability along the coast of Saudi Arabia. Samples were collected at nine coral reefs spanning approximately 1500 km, from the Gulf of Aqaba in the northern Red Sea to the Farasan Archipelago in the southern Red Sea. Thirteen Chaetognatha species belonging to two families (Sagittidae and Krohnittidae) were identified. Latitudinal environmental changes and availability of prey (i.e. Copepoda, Crustacea) altered Chaetognatha density and distribution. The cosmopolitan epiplanktonic Flaccisagitta enflata (38.1%) dominated the Chaetognatha community, and its abundance gradually decreased from South to North. Notable were two mesopelagic species (Decipisagitta decipiens and Caecosagitta macrocephala) in the near-reef surface mixed layers at some sites. This was related to wind-induced upwelling of deep water into the coral reefs providing evidence of trophic oceanic subsidies. Most Sagittidae occurred in higher abundances at night, whereas Krohnittidae were more present during the day. Chaetognatha with developing (stage II) or mature ovaries (stage III) were more active at night, demonstrating stage-specific diel vertical migration as a potential predator avoidance strategy.

Strong Sensitivity of Red Sea Zooplankton to UV-B Radiation

The impacts of UV-B radiation to Red Sea coastal zooplankton was assessed experimentally at the time (May/June) of peak UV-B radiation, using the most abundant zooplankton species in the community (eight copepod genera, a cladoceran, an ostracod, a cumacean, and two meroplankton, including crab zoeae and megalopa). Mortality rates increased greatly in the presence of ambient UV-B radiation for all species tested except for Labidocera, Macrosetella, and the crab megalopa larvae. Mortality rates declined, on average, threefold when UV-B radiation was removed. These results provide evidence that Red Sea zooplankton are highly vulnerable to ambient levels of UV-B radiation.

Complete larval development of the Brachyuran crab (Epixanthus Frontalis H. Milne Edwards, 1834) (Crustacea, Decapoda, Eriphioidea, Oziidae) under laboratory conditions.

The complete larval development of the oziid crab Epixanthus frontalis (H. Milne Edwards, 1834) hatched from ovigerous specimens collected from Saso Island, southern Red Sea, was obtained under laboratory conditions. Four zoeae, one additional zoea and a megalopa were obtained and these are described and illustrated in detail for the first time. Larvae of this species can be differentiated from those of other oziid species based on a combination of characters such as the number of aesthetascs and setae of the antennule, and the coxal and basial setal numbers and patterns of the maxilla and maxillule.

Calcinea of the Red Sea: providing a DNA barcode inventory with description of four new species

The Red Sea is a biodiversity hotspot with a considerable percentage of endemic species for many marine animals. Little is known about the diversity and distribution of calcareous sponges (Porifera, Class Calcarea) in this marginal sea. Here we analysed calcareous sponges of the subclass Calcinea that were collected between 2009 and 2013 at 20 localities in the Red Sea, ranging from the Gulf of Aqaba in the north to the Farasan Islands in the south, to document the species of this region. For this, we applied an integrative approach: We defined OTUs based on the analyses of a recently suggested standard DNA marker, the LSU C-region. The analysis was complemented with a second marker, the internal transcribed spacer, for selected specimens. Ten OTUs were identified. Specimens of each OTU were morphologically examined with spicule preparations and histological sections. Accordingly, our ten OTUs represent ten species, which cover taxonomically a broad range of the subclass. By combining molecular and morphological data, we describe four new species from the Red Sea: Soleneiscus hamatus sp. nov., Ernstia arabica sp. nov., Clathrina rotundata sp. nov., and Clathrina rowi sp. nov.. One additional small specimen was closely related to “Clathrina” adusta, but due to the small size it could not be properly analysed morphologically. By providing the DNA sequences for the morphologically documented specimens in the Sponge Barcoding Database (www.spongebarcoding.org) we facilitate future DNA-assisted species identification of Red Sea Calcinea, even for small or incomplete samples, which would be insufficient for morphological identification. Application of DNA barcode methods in the subclass will help to further investigate the distribution of Calcinea in the Red Sea and adjacent regions.

Description of a new genus and new species of Sesarmidae (Decapoda: Brachyura) from the Farasan Islands, Saudi Arabia, Red Sea

A new genus, Eneosesarma, is created for a new species of sesarmid crab, E. azizi, from Saso Island, Farasan Archipelago, Saudi Arabia. The new species shows close affinities with species of the sesarmid genera Sesarmoides Serene and Soh, 1970 and Karstarma Davie and Ng, 2007, but differs from these in regard to carapace shape, morphology of male G1, and absence of stridulatory organ.