Green turtles (Chelonia mydas) foraging at Arvoredo Island in Southern Brazil: Genetic characterization and mixed stock analysis through mtDNA control region haplotypes

We analyzed mtDNA control region sequences of green turtles (Chelonia mydas) from Arvoredo Island, a foraging ground in southern Brazil, and identified eight haplotypes. Of these, CM-A8 (64%) and CM-A5 (22%) were dominant, the remainder presenting low frequencies (< 5%). Haplotype (h) and nucleotide (π) diversities were 0.5570 ± 0.0697 and 0.0021 ± 0.0016, respectively. Exact tests of differentiation and AMOVA ΦST pairwise values between the study area and eight other Atlantic foraging grounds revealed significant differences in most areas, except Ubatuba and Rocas/Noronha, in Brazil (p > 0.05). Mixed Stock Analysis, incorporating eleven Atlantic and one Mediterranean rookery as possible sources of individuals, indicated Ascension and Aves islands as the main contributing stocks to the Arvoredo aggregation (68.01% and 22.96%, respectively). These results demonstrate the extensive relationships between Arvoredo Island and other Atlantic foraging and breeding areas. Such an understanding provides a framework for establishing adequate management and conservation strategies for this endangered species

Global Diversity of Ascidiacea

The class Ascidiacea presents fundamental opportunities for research in the fields of development, evolution, ecology, natural products and more. This review provides a comprehensive overview of the current knowledge regarding the global biodiversity of the class Ascidiacea, focusing in their taxonomy, main regions of biodiversity, and distribution patterns. Based on analysis of the literature and the species registered in the online World Register of Marine Species, we assembled a list of 2815 described species. The highest number of species and families is found in the order Aplousobranchia. Didemnidae and Styelidae families have the highest number of species with more than 500 within each group. Sixty percent of described species are colonial. Species richness is highest in tropical regions, where colonial species predominate. In higher latitudes solitary species gradually contribute more to the total species richness. We emphasize the strong association between species richness and sampling efforts, and discuss the risks of invasive species. Our inventory is certainly incomplete as the ascidian fauna in many areas around the world is relatively poorly known, and many new species continue to be discovered and described each year

Precision Clock and Time Transfer on a Wireless Telecommunication Link

Precise time dissemination is a key requirement for remote clock synchronization used in coordinated command of distributed actuators in various applications. We present a newly conceived low-cost clock system based on the time-to-digital converter (TDC) principle to generate, transfer, and compare time-coded sequences (TCSs) with nanosecond accuracy using a wireless telecommunication link. The clock principle counts pulse sequences with nanosecond precision derived from a low-frequency oven-controlled crystal oscillator (OCXO) stable frequency standard. The TCSs are transmitted to a remote transponder that distributes them to receiving stations, where the clock readings are processed. A simple short-range wireless telecommunication link was assembled to demonstrate the system. The repeated TCSs are received back and compared with the reference clock. We describe the clock, the telecommunication setup, and the electrical and electronic sources of delays. Comparison of mean TCSs taken every 0.629 s provided a time-domain midterm stability Allan deviation of about 1.3 x 10(-11) at tau = 10(3) s. These results show the feasibility of a low-cost GPS-independent technique, exhibiting highly performing time-domain midterm stability. This system is a key requirement for a new proposed system for geopositioning.593512518Brazilian National Funding Agency for Studies and Research (FINEP) [01.05.0034.00]Brazilian National Funding Agency for Studies and Research (FINEP) [01.05.0034.00