A comparative study of Seagrasses Species in Regional Seas and QMZ

Seagrasses are flowering monocot green plants that have adapted to marine life, and remain completely immersed in seawater and are primary producers of food for numerous marine animals. Seagrasses are of worldwide distribution and it was earlier estimated that there are approximately 60-72 known species of seagrasses. It is now evident that the number of seagrasses species is almost 200, comprising 25 genera and 5 families, namely Cymodoceaceae, Hydrocharitaceae, Posidoniaceae, Zosteraceae and Ruppiaceae, covering a global area of 300,000-600,000 km2. It is also estimated that they have declined in area by 29%. The Western Indo-Pacific realm encompasses 13 species in two families; the Cymodoceacae with 4 genera and the Hydrocharitaceae with 3 genera. Twelve species extend into the Red Sea, 4 occur in the Arabian/Persian Gulf and 4 in the Arabian Sea. The total area of Qatar marine zone (EEZ) is approximately 35,000km2 and three species of seagrasses are known to occur in this zone. These are Halophila stipulacea, Halophila ovalis and Halodule uninervisis, the most common one. It is established that seagrasses consolidate and stabilize bottom sediments, create and maintain good water quality (clarity), produce oxygen, provide food, nursery ground for many animals and have been proven to be very important in GHG emissions.

Морская граница в прибрежно-морском природопользовании и вариант ее выделения по глубине

The existing approaches and regulations for the determination of the marine boundaries of the part of coastal-marine natural management are analyzed. There are no uniform boundaries in the direction toward the sea, despite the presence of numerous definitions of the coastal zone. For the purposes of maritime activities management, i.e. coastal and oceanic natural management, the geomorphological definition of the coastal zone becomes insufficient due to the greater dependence on the land space. Therefore, it is proposed to use the term "coastal-marine zone" with a broader definition, including, in addition to territorial, coastal and aquatic structures. The coastal-sea zone boundaries can be established depending on the research objectives. In our research, we suggest to establish this kind of depth boundary, considering it a limiting factor of marine economic activities.

A source of isotopically light organic carbon in a low-pH anoxic marine zone

Geochemical and stable isotope measurements in the anoxic marine zone (AMZ) off northern Chile during periods of contrasting oceanographic conditions indicate that microbial processes mediating sulfur and nitrogen cycling exert a significant control on the carbonate chemistry (pH, AT, DIC and pCO2) of this region. Here we show that in 2015, a large isotopic fractionation between DIC and POC, a DIC and N deficit in AMZ waters indicate the predominance of in situ dark carbon fixation by sulfur-driven autotrophic denitrification in addition to anammox. In 2018, however, the fractionation between DIC and POC was significantly lower, while the total alkalinity increased in the low-pH AMZ core, suggesting a predominance of heterotrophic processes. An isotope mass-balance model demonstrates that variations in the rates of sulfur- and nitrogen-mediated carbon fixation in AMZ waters contribute ~7–35% of the POC exported to deeper waters. Thus, dark carbon fixation should be included in assessments of future changes in carbon cycling and carbonate chemistry due to AMZ expansion.

Distribution and Diversity of Benthic Marine Macroalgae in Islands around Qatar

Extending into the Arabian Gulf, Qatar is surrounded by a number of islands mostly scattered by the eastern coastline. With the unique physical characteristics of the Gulf, which is a highly saline sea with high seawater temperatures, there is an urge need to investigate the macroalgae living in such harsh environment. Macroalgae plays an important role in the food web as they are primary producers and providers of food for other organisms. They also provide shelter and habitat in the marine ecosystem for herbivorous fish and other invertebrate animals. Additionally, macroalgae plays an outstanding role in reducing CO2 from the atmosphere and increasing the level of dissolved oxygen in their immediate environment. However, there are few studies on marine macroalgae in Qatar and no previous studies found related to macroalgae from the islands around Qatar. The present work contributes to the macroalgae research by providing the first survey of distribution and diversity of benthic marine macroalgae in islands around Qatar. The marine benthic green, red and brown macroalgae of intertidal and subtidal in marine zone areas around Qatar were collected during Qatar’s Islands project, which started 2018. The collected macroalgae are documented and a total of 67 species of macroalgae are recorded for all islands around Qatar, 24 Chlorophyta (Green algae), 25 Rhodophyta (Red algae) and 18 species Phaeophyta (Brown algae). The Red algae are dominant taxon in term of species richness, accounting for an average of 37% of the species at all study sites. The islands which had more species are Al-Beshaireya 58 Species, Al-Aaliya 53 Species, Sheraouh 48 Species, Janan 43 Species and Bu Felaita 37 Species. Our results show that islands located at eastern and southeastern coast of Qatar have more diversity of algae species than those located at the western and northwestern coast.

Spatial distribution of phytoplankton in the subarctic estuary (Kem’ river, the White Sea)

The species composition and biomass of the phytoplankton (Ph) as well as hydrological characteristics were estimated in 4 spatial surveys in the subarctic tidal estuary of the Kem’ River and adjacent area of Onega Bay (White Sea, Russia) in June–July 2008–2011. The study area was divided into 3 zones (the river zone, the gradient zone and the marine zone), based on the salinity variation of the surface layer. In total, 318 species of Ph were registered, 143 species are found in the river zone, 225 — in the gradient zone, 106 — in the marine zone. The greatest number of species in all zones was represented by diatoms. The highest biodiversity of Ph in the surface layer was detected in the gradient zone. The averages of total biomass of the Ph in the surface layer (Bo) at different years varied in range 2.8–16.9 mg C/m3. Although Bo did not differ significantly between zones, with the exception of 2011, when Bo was the highest in the river zone, dissimilarity in the structure of the Ph in the river, gradient and marine zones were 61–95%. The similarity of the Ph at the stations of each zone was poor (22–53%) with the lowest values in the gradient zone. It is postulated that the tidal cycles determine the spatial and temporal heterogeneity of the composition, structure and abundance of Ph in the Kem’ river estuary in summer.

Cephalopod Nervous System Organization

Over 700 species of cephalopods live in the Earth’s waters, occupying almost every marine zone, from the benthic deep to the open ocean to tidal waters. The greatly varied forms and charismatic behaviors of these animals have long fascinated humans. Cephalopods are short-lived, highly mobile predators with sophisticated brains that are the largest among the invertebrates. While cephalopod brains share a similar anatomical organization, the nervous systems of coleoids (octopus, squid, cuttlefish) and nautiloids all display important lineage-specific neural adaptations. The octopus brain, for example, has for its arms a well-developed tactile learning and memory system that is vestigial in, or absent from, that of other cephalopods. The unique anatomy of the squid giant fiber system enables rapid escape in the event of capture. The brain of the nautilus comprises fewer lobes than its coleoid counterparts, but contains olfactory system structures and circuits not yet identified in other cephalopods.