Horizon Picking from SBP Images Using Physicals-Combined Deep Learning

Horizon picking from sub-bottom profiler (SBP) images has great significance in marine shallow strata studies. However, the mainstream automatic picking methods cannot handle multiples well, and there is a need to set a group of parameters manually. Considering the constant increase in the amount of SBP data and the high efficiency of deep learning (DL), we proposed a physicals-combined DL method to pick the horizons from SBP images. We adopted the DeeplabV3+ net to extract the horizons and multiples from SBP images. We generated a training dataset from the Jiaozhou Bay survey (Shandong, China) and the Zhujiang estuary survey (Guangzhou, China) to increase the applicability of the trained model. After the DL processing, we proposed a simulated Radon transform method to eliminate the surface-related multiples from the prediction by combining the designed pseudo-Radon transform and correlation analysis. We verified the proposed method using actual data (not involved in the training dataset) from Jiaozhou Bay and Zhujiang estuary. The positions of picked horizons are accurate, and multiples are suppressed.

Distribution, seasonality, optical characteristics, and fluxes of dissolved organic matter (DOM) in the Pearl River (Zhujiang) estuary, China

Dissolved organic carbon concentration in the Pearl River estuary (PRE) of China was measured in May, August, and October 2015 and January 2016. Chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) in the latter three seasons were characterized by absorption and fluorescence spectroscopy. Parallel factor analysis of the fluorescence spectra identified two protein-like, two humic-like, and one oxidized quinone-like FDOM components. The seasonality of average DOM abundance varied as follows: DOC: May (156 μmol L−1) > January (114 μmol L−1) ≈ August (112 μmol L−1) > November (86 μmol L−1); CDOM absorption at 330 nm: August (1.76 m−1) > November (1.39 m−1) ≈ January (1.30 m−1); FDOM expressed as the sum of the maximum fluorescence intensities of all FDOM components: November (1.77 R.U.) > August (1.54 R.U.) ≈ January (1.49 R.U.). Average DOM abundance in surface water was higher than in bottom water, their difference being marginal (0.1–10 %) for DOC in all seasons and for CDOM and FDOM in November and January, and moderate (16–21 %) for CDOM and FDOM in August. DOC showed little cross-estuary variations in all seasons while CDOM and FDOM in January were higher on the west side of the estuary than in the middle and on the east side. All three variables exhibited large variations and/or rapid drawdowns at the head of the estuary (salinity

MORPHOMETRIC ANALYSIS AND REPRODUCTIVE BIOLOGY OF THE CRAB CHARYBDIS AFFINIS (DECAPODA, BRACHYURA, PORTUNIDAE) FROM THE ZHUJIANG ESTUARY, CHINA

Morphometric characters and organ indices were analyzed in Charybdis affinis collected at different seasons from the Zhujiang estuary, China. The crab is heterochelous, with pronounced right handedness in both sexes. There is a marked sexual difference in relative growth of the cheliped. The female abdomen increases in size at puberty, which is also accompanied by a reduced allometric growth rate. Analysis of gonad development gave the estimate of 50% gonadal maturity at 42 and 36 mm carapace width for females and males, respectively. The hepatosomatic index of female crabs is inversely related to the gonadosomatic index indicating the role of the hepatopancreas in storage of nutrients necessary for ovarian development in the reproductive season. Les caracteres morphologiques et les indices relatifs aux organes ont ete analyses chez Charybdis affinis, recolte a differentes saisons dans l'estuaire du Zhujiang, Chine. Le crabe presente une heterochelie, la pince droite etant tres developpee dans les deux sexes. Il existe une difference sexuelle marquee dans la croissance relative du chelipede. L'abdomen femelle s'accroot en taille a la puberte, ce qui s'accompagne aussi d'un taux de croissance allometrique reduit. L'analyse du developpement des gonades a donne une maturite estimee a 50% pour des femelles et males, respectivement, ayant une largeur de la carapace de 42 et 36 mm. L'indice hepatosomatique des crabes femelles est inversement proportionnel a l'indice gonadosomatique ce qui indique le role de l'hepatopancreas dans le stockage des nutriments necessaire au developpement ovarien lors de la reproduction.