Conspicuous and cryptic reef fishes from a unique and economically important region in the northern Red Sea

Spatial patterns in reef fish biomass and trait structure along a natural environmental gradient

Biodiversity loss is a fundamental concern across marine and terrestrial ecosystems in virtue of continued and increasing localized and global human activities. Accordingly, it is essential to discern how communities vary in space across a range of environmental and disturbance scales. Increasingly, ecological traits are providing important mechanisms for understanding communities based on the trait's species provide, building upon traditional assessments of taxonomic identity. This study investigated trait and biomass indices constructed from fish communities from 94 reefs along 2000 kms of latitude along the Red Sea. Fish communities were recorded through in situ visual surveys and covered varying coastal population density and a natural linear gradient in environmental parameters (sea surface temperature, productivity, salinity). From these communities, a total of 153 unique functional entities (FEs) were recorded. Using key components of trait diversity, Red Sea reefs contain low trait redundancy and high vulnerability, with 71% of FEs represented by a single species. Despite the strong linear gradient in environmental variables along the latitudinal range, functional richness and diversity did not reflect this, suggesting that local scale environmental variability and stressors may have a greater, and or additive influence. Standing biomass and biomass productivity was highest in the Farasan Banks (southern Red Sea) while biomass productivity was lowest in the two far northern regions. The high biomass in the Farasan Banks was largely driven by planktivore species, suggesting a link with higher levels of primary productivity and warmer water temperature in the south. The region with the highest trait vulnerability was adjacent to a major city and industrial port, suggesting a link between vulnerability and coastal population. This study provides a baseline for the region and a mechanism to support recommendations on the assessment of vulnerable reef fish communities at regional scales beyond taxonomic assessments.

A generalized machine learning model for long-term coral reef monitoring in the Red Sea

Coral reefs, despite covering less than 0.2 % of the ocean floor, harbor approximately 35 % of all known marine species, making their conservation critical. However, coral bleaching, exacerbated by climate change and phenomena such as El Niño, poses a significant threat to these ecosystems. This study focuses on the Red Sea, proposing a generalized machine learning approach to detect and monitor changes in coral reef cover over an 18-year period (2000-2018). Using Landsat 7 and 8 data, a Support Vector Machine (SVM) classifier was trained on depth-invariant indices (DII) derived from the Gulf of Aqaba and validated against ground truth data from Umluj. The classifier was then applied to Al Wajh, demonstrating its robustness across different sites and times. Results indicated a significant decline in coral cover: 11.4 % in the Gulf of Aqaba, 3.4 % in Umluj, and 13.6 % in Al Wajh. This study highlights the importance of continuous monitoring using generalized classifiers to mitigate the impacts of environmental changes on coral reefs.

Acanthopagrus oconnorae, a new species of seabream (Sparidae) from the Red Sea

A new species of sparid fish, Acanthopagrus oconnorae, is described based on 11 specimens collected in the shallow (0-1 m depth) mangrove-adjacent sandflats of Thuwal, Saudi Arabia. The new species is distinguished from its congeners by the following combination of characters: second anal-fin spine 12.8%-16.6% of standard length (SL); 3½ scale rows between the fifth dorsal-fin spine and lateral line; suborbital width 5.7%-6.7% of SL; eyes positioned at the anterior edge of the head, often forming a weakly convex break in an otherwise gently curved head profile, when viewed laterally; caudal fin light yellow with black posterior margin (approximately half of fin); anal fin dusky grey, with posterior one-fifth of the fin light yellow; black streaks on inter-radial membranes of anal fin absent. The most similar species to A. oconnorae is Acanthopagrus vagus, which differs by the presence of a w-shaped anterior edge of the scaled predorsal area, a more acute snout and black streaks on the inter-radial membranes of the anal fin. Phylogenetic placement and species delimitation of A. oconnorae are discussed based on COI, CytB and 16S sequences. It is hypothesized that ecology and behaviour explain how this species avoided detection despite its likely occurrence in coastal areas of the Red Sea with historically high fishing pressure.

Population dynamics and fecundity estimates of Long-spined Black Sea Urchin Diadema savignyi (Audouin, 1890) from the Red Sea, Saudi Arabia

Sea Urchin is not only the crucial keystone species for the coral reef restoration but also it has antimicrobial and anti-cancer activities. This study undertaken to focus on length weight relationship, size fecundity distribution and the estimation of fecundity from the long-spined Sea Urchin, Diadema savignyi at the coastal water of the middle Red Sea, Saudi Arabia. A total of 633 specimen of D. savignyi has been collected from the coastal water of Obhur Creak during the sampling time. In each species, total length (TL) measured as a TW = 11.908 × 0.9995 (R² = 0.8975) through the linear regression graph and digital slide callipers and, individual body weight estimated by the digital balance. The natural and fishing mortality 2.02/yr and 0.19/yr respectively has documented from study area. The Asymptotic length value (L∞) (cm) were estimated 7.35 where the growth coefficient (K) was 0.67 from the monthly length-frequency numeric data by using FAO FISAT II software for generating and estimating the population parameters and age. However, the recruitment pattern was observed to be increased gradually with the maximum recruitment peak between the months of September and October 2021. Therefore, the estimation of fecundity varied from 49,226 ova (total length 3.1 cm) to 466,133 ova (total length 6.8). As a result, analysis of the relationship between the absolute fecundity (F) and total length (TL), and between the fecundity and drained body weight (DW), revealed a linear regression model with a positive and significant relationship at p < 0.05. This is the first approach to study the detailed population dynamic of the ecologically and economically important tropical long spine sea urchin (D. savignyi) endemic to the region. However, the result so far obtained from this research would greatly be useful towards the understanding of the detailed population structure and growth patterns that will undoubtedly help us to develop captive breeding, seed production, culture protocols, conservation strategies and isolation bioactive compounds of this high-valued species incommensurate with national and international perspectives.

A review of the Eviotazebrina complex, with descriptions of four new species (Teleostei, Gobiidae)

The Eviotazebrina complex includes eight species of closely-related dwarfgobies, four of which are herein described as new. The complex is named for Eviotazebrina Lachner & Karnella, 1978, an Indian Ocean species with the holotype from the Seychelles Islands and also known from the Maldives, which was once thought to range into the Gulf of Aqaba and the Red Sea eastward to the Great Barrier Reef of Australia. Our analysis supports the recognition of four genetically distinct, geographically non-overlapping, species within what was previously called E.zebrina, with E.zebrina being restricted to the Indian Ocean, E.marerubrum sp. nov. described from the Red Sea, E.longirostris sp. nov. described from western New Guinea, and E.pseudozebrina sp. nov. described from Fiji. The caudal fin of all four of these species is crossed by oblique black bars in preservative, but these black bars are absent from the four other species included in the complex. Two of the other species within the complex, E.tetha and E.gunawanae are morphologically similar to each other in having the AITO cephalic-sensory pore positioned far forward and opening anteriorly. Eviotatetha is known from lagoonal environments in Cenderawasih Bay and Raja Ampat, West Papua, and E.gunawanae is known only from deeper reefs (35-60 m) from Fakfak Regency, West Papua. The final two species are E.cometa which is known from Fiji and Tonga and possesses red bars crossing the caudal fin (but lost in preservative) and a 9/8 dorsal/anal-fin formula, and E.oculineata sp. nov., which is described as new from New Guinea and the Solomon Islands, and possesses an 8/7 dorsal/anal-fin formula and lacks red caudal bars. Eviotaoculineata has been confused with E.cometa in the past.

Neopomacentrus flavicauda: a replacement name for Neopomacentrus xanthurus Allen amp; Randall, 1981 (Perciformes: Pomacentridae), a secondary junior homonym of Dascyllus xanthurus Bleeker, 1853

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