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The Caspian Sea, the world's largest inland body of water, supports a highly diverse community of phytoplankton species that play a crucial role in its ecosystem and overall food web dynamics. This unique, enclosed environment, which spans several countries, is subject to various ecological pressures, including climate change and anthropogenic activities, making it a critical area for biodiversity research. In this study, a comprehensive checklist of these species has been compiled based on an extensive literature review, revealing a total of 970 species and subspecies from 242 genera across 7 phyla. Bacillariophyceae was identified as the dominant class, comprising 347 species (36.37%), followed by Chlorophyta with 289 species (30.29%) and Cyanobacteria with 190 species (19.92%). Other notable groups include Myzozoa with 72 species (7.55%), Ochrophyta with 56 species (5.87%), Cryptophyta with 13 species (1.36%), and Haptophyta with 3 species (0.31%). This detailed inventory provides essential data on the phytoplankton biodiversity in the Caspian Sea, contributing to a deeper understanding of its ecological complexity. The checklist not only highlights the diversity within each phylum but also emphasizes the dominance of diatoms and chlorophytes, which are key to the sea's primary productivity. These findings serve as a critical resource for future ecological and environmental assessments, offering a baseline for monitoring biodiversity changes, potential threats to the ecosystem, and the impacts of climate change and human activities. The rich phytoplankton diversity outlined in this study shows the ecological significance of the Caspian Sea and its importance for regional and global biodiversity conservation efforts. [ABSTRACT FROM AUTHOR]

Context: Driven by growing human populations and climate change-mitigation concerns, artificial coastal structures have become crucial for meeting population needs. However, these structures differ from natural counterparts and can reduce biodiversity and species abundance. Aims: This study aimed to use rock pools as an eco-engineering approach to mitigate these negative effects and enhance species diversity on coastal infrastructure. Methods: We incorporated rock pools of two different sizes into three distinct intertidal levels within a concrete-block breakwater at the Strait of Hormuz, Persian Gulf, and conducted an in situ assessment of the biota in rock pools and their adjacent emergent surfaces. Key results: In total, 17 taxa were identified. The findings showed a five-fold increase in cumulative species number and a 30% rise in abundance owing to the presence of rock pools. PERMANOVA results indicated that rock pool size, intertidal levels, and their interaction, significantly influenced species richness. Conclusions: Our investigation underscores the effectiveness of integrating rock pools as an ecological engineering approach to enrich species diversity on human-made structures within intertidal zones. Implications: The selection of rock pool dimensions and tidal positioning should be thoughtfully determined, considering the prevailing environmental conditions and the project's objectives. As human populations and climate-change concerns increase, artificial coastal structures have become essential. However, they often harm marine biodiversity. To mitigate this impact, we artificially incorporated rock pools into a concrete-block breakwater. The study showed a significant increase in species richness and abundance owing to the presence of rock pools. [ABSTRACT FROM AUTHOR]

Elevated atmospheric CO2 concentration and changes in precipitation patterns affect plant physiological processes and alter ecosystem functions. In combination, the interactions between these factors result in complex responses that challenge our current understanding. We aimed to investigate the effects of elevated CO2 and drought stress on the growth and physiology traits of One-year-old Pistacia atlantica seedlings. Seedlings of P. atlantica were grown at two different CO2 concentrations (ambient 380 ppm and elevated 700 ppm) and the two irrigation regimes (100% and 50% of field capacity) for one growing season. Seedlings collar diameter, height, leaf area, biomass accumulation, root length and volume, photosynthetic parameters, pigment content, and relative water content increased at elevated CO2. At the same time, the amounts of proline, electrolyte leakage, malondialdehyde, and antioxidant enzymes decreased at elevated CO2. Drought stress had negative effects on the measured growth parameters. These, however, ameliorate in the presence of elevated CO2 through enhanced photosynthesis performance and maintaining better water status, and possibly also by a reduction of oxidative stress. Increased CO2, as expected in a future climate, might thus mitigate the negative effects of drought in P. atlantica trees under natural conditions. [ABSTRACT FROM AUTHOR]

We investigated the impacts of warming and elevated pC[O.sub.2] on newly settled Amphibalanus improvisus from Kiel Fjord, an estuarine ecosystem characterized by significant natural pC[O.sub.2] variability. In two experiments, juvenile barnacles were maintained at two temperature and three pC[O.sub.2] levels (20/24 °C, 700-2,140 µatm) for 8 weeks in a batch culture and at four pC[O.sub.2] levels (20 °C, 620-2,870 µatm) for 12 weeks in a water flow-through system. Warming as well as elevated pC[O.sub.2] hardly affected growth or the condition index of barnacles, although some factor combinations led to temporal significances in enhanced or reduced growth with an increase in pC[O.sub.2]. While warming increased the shell strength of A. improvisus individuals, elevated pC[O.sub.2] had only weak effects. We demonstrate a strong tolerance of juvenile A. improvisus to mean acidification levels of about 1,000 µatm pC[O.sub.2] as is already naturally experienced by the investigated barnacle population., Introduction Anthropogenically, increased atmospheric C[O.sub.2] causes a reduction in seawater pH, commonly referred to as ocean acidification ('OA'; Caldeira and Wickett 2003; IPCC 2007; Gattuso and Hansson 2011). This process [...]

When juvenile mortality or juvenile growth is impacted by temperature and salinity, these factors have a substantial effect on recruitment success and population dynamics in benthic ecosystems. Using freshly settled cyprids of Amphibalanus improvisus, we investigated the combined effects of temperature (12, 20 and 28°C) and salinity (5, 15 and 30 psu) on early juvenile stage performance. Mortality as well as size (basal diameter, dry weight, and ash-free dry weight) was monitored for a period of 40 days. Mortality was high (42-63%) during the first week following attachment, regardless of the temperature and salinity treatments. Subsequently, mortality and size were interactively influenced by temperature and salinity. Highest mortality and lowest size of juveniles occurred at lowest temperature (12°C) and salinity (5 psu). Apparently, low temperature (12°C) narrowed the barnacles' salinity tolerance. Juvenile barnacles constructed more shell material compared to body mass at high temperature and high salinity, while a reverse situation was observed at low temperature and low salinity. Our results demonstrate that environmental changes can directly and/ or indirectly alter patterns of survivorship and size. Warming and desalination as predicted for the Baltic Sea in the course of climate change may, however, act antagonistically and compensate each other's isolated effect on barnacles., Introduction Barnacle ontogeny shows a complex life cycle in which the nauplius larva molts six times before transforming into the cypris stage. The competent cyprid explores the potential settlement substratum [...]

The molluscan fauna of the Persian Gulf has recently been relatively well documented, yet there are few records of heterobranch sea slugs (opisthobranchs) from the Arabian parts and no report from the Iranian waters. Here we report for the first time the occurrence of one of these molluscs in the northern Persian Gulf (Bandar Abbas, Iran). Sacoglossan specimens were collected in association with the seaweed, Caulerpa sertularioides. Since morphological attributes were not adequately reliable for species identification, molecular approaches were carried out. Maximum-likelihood and Bayesian Inference analysis of partial DNA sequences of the mitochondrial cytochrome c oxidase subunit I (COI) locus were used for DNA barcoding of large-bodied specimens of Elysia. All Persian Gulf specimens were genetically confirmed as Elysia cf. tomentosa sp. 5, one of at least five morphologically similar but genetically distinct species in the taxonomically challenging and unresolved E. tomentosa complex. This species has previously been recorded only from Australia and Thailand and our finding adds another distant point to the geographic distribution of this species. [ABSTRACT FROM AUTHOR]