Distribution and abundance of dinoflagellates from the coastal waters of Karachi, Pakistan, northern part of the Arabian Sea

The present study reports on seasonal and spatial variations in diversity, distribution and abundance of dinoflegellates and indicates the presence of HAB species in Pakistan waters. A total of 179 taxa, recorded in this study from offshore and near-shore waters, belong to 41 genera in 26 families and 10 orders. The high species count (149 species) was recorded from Manora Island offshore station (MI-1) and 105 spp, 109 spp and 115 spp were encountered from the Mubarak village offshore station (MV-1), Manora near shore station (MI-2) and Mubarak Village near-shore station (MV-2) respectively. Tripos furca was the dominant and frequently occurring species (> 1 x103 to > 25 x103 cells L-1 from coastal and >1x 105 cells L-l from near-shore stations) in addition to less abundant Alexandrium catenella, Alexandrium sp., Alexandrium minutum, and Prorocentrum micans (>103 to 25x 103cells/L). Another 44 species occurred in relatively low numbers (<103 cell L-l). Seventy species were found throughout the study period at all four stations. High number of species in three genera (Tripos (38), Protoperidinium (34) and Prorocentrum (20) was recorded. Potently toxic (16 genera 43 species) and HAB related (19 genera and 30 species) dinoflagellate taxa were also recorded. The percent contribution of dinoflagellates in total phytoplankton population generally remained below 20% except for a few instances. Manora Island stations had comparatively higher Shannon index and equitability and slightly lower dominance index. The PCA plot showed strong positive correlation among chlorophyll-a concentration, dissolved oxygen, total number of phytoplankton and dinoflagellates.

Design of a Cabled Seafloor Observatory for Marine Ecological Environment Monitoring

Cabled seafloor in-situ observation systems have drawn much attention in recent years for their capability of facilitating long-term all-weather deep-sea data-intense marine observations. The Penglai in-situ seafloor observation system for ecological environment monitoring is proposed in this paper. The current system consists of an on-shore station, a primary node, and two secondary nodes, but more nodes can be hosted due to its scalability. A looped backbone network connects the on-shore station and primary nodes. Each primary node can host up to four secondary nodes, and each secondary node can host up to eight different sensors. Marine observation data and system work state data are collected and backed up by the on-shore station in a real-time manner. Users can access the ocean observation data via a web page interface. The proposed system has been deployed for more than half a year and will continue to work after that. The field experiment showed that the proposed system worked smoothly in system state monitoring and marine data acquisition. A large amount of oceanographic data with videos has been achieved for future studies.

The Single-Shore-Station-Based Position Estimation Method of an Automatic Identification System

In order to overcome the vulnerability of the Global Navigation Satellite System (GNSS), the International Maritime Organization (IMO) initiated the ranging mode (R-Mode) of the automatic identification system (AIS) to provide resilient position data. As the existing AIS is a communication system, the number of shore stations as reference stations cannot satisfy positioning requirements. Especially in the area near a shore station, it is very common that a vessel can only receive signals from one shore station, where the traditional positioning method cannot be used. A novel position estimation method using multiple antennas on shipborne equipment is proposed here, which provides a vessel’s position even though the vessel can only receive signals from a single shore station. It is beneficial for solving positioning issues in proximity to the coast. Further, as the distances between different antennas to the shore station are not sufficiently independent, the positioning matrix can easily be near singularity or ill-conditioned; thus, an effective position solving method is derived. Furthermore, the proposed method is verified and evaluated in different scenarios by numerical simulation. We assessed the influencing factors of positioning performance, such as the vessel’s heading angle, the relative position, and the distances between the shore station and the vessel. The proposed method widely expands the application scope of the AIS R-Mode positioning system.

Chr. Christensen and C. A. Larsen: A comparative analysis of two whaling entrepreneurs

Chr. Christensen and C. A. Larsen are usually considered among the most important pioneers in the transfer of whaling to Antarctic waters in the early twentieth century. After a period of close cooperation during the 1890s, they took different courses and built up their Antarctic enterprises independently of each other. While Larsen initiated the foundation of shore station whaling at South Georgia, Christensen sent a floating factory ship to the South Shetland Islands. The main aim of the paper is to make a systematic comparison of the two entrepreneurs and their companies, and focus explicitly on the considerations and decisions they made when whaling was transferred from north to south. They obviously chose different strategies, but we will ask how different they really were in their thinking about how southern whaling was going to develop. Both entrepreneurs brought along their experiences from how whaling had been undertaken in the northern waters. It was not obvious what organizational patterns would work in the south, and we shall study how familiar and new ways of organizing the industry were combined – as is often the case in entrepreneurial innovations.

FORAMINIFERA BENTONIK KAITANNYA DENGAN KUALITAS PERAIRAN DI WILAYAH BARAT DAYA PULAU MOROTAI, MALUKU UTARA

Pulau Morotai, Maluku Utara merupakan salah satu pulau yang terletak di kawasan segitiga terumbu karang sebagai pusat kenakeragaman biota laut global. Kesehatan ekosistem terumbu karang dapat dipantau dengan menggunakan komposisi foraminifera bentonik. Maksud dan tujuan studi ini adalah untuk mengetahui struktur komunitas foraminifera bentoni terkait dengan kualitas perairan sebelah barat daya Pulau Morotai. Studi ini menggunakan enam sampel sedimen dasar laut dengan tiga kali perulangan yang diambil pada kedalaman antara 16 dan 36 m. Hasilnya menunjukkan ada 28 spesies foraminifera bentonik, dicirikan oleh kehadiran Amphistegina dan Operculina dalam jumlah sangat melimpah. Amphistegina radiata merupakan spesies dengan densitas tertinggi di stasiun dekat pantai. Nilai indeks keanekaragaman foraminifera antara 1,49 dan 2,31 yang tergolong dalam kondisidengan tingkat keanekaragaman sedang. Indeks keseragaman umumnya lebih besar dari 0,6 yang menunjukkan lingkungan stabil. Nilai indeks FORAM (FI) berkisar dari 6,32 hingga 9,16 yang memperlihatkan kondisi lingkungan yang kondusif bagi pertumbuhan terumbu karang. Kata kunci: struktur komunitas, foraminifera bentonik, terumbu karang, MorotaiMorotai Island, North Molucca is one of islands that is located in the Coral triangle region as the global centre of marine biodiversity. The health of this coral ecosystem could be monitored by using benthonic foraminferal composition. The purpose of this study are re recognized community structure of benthic foraminifera related to water quality off southwest Morotai, Island. This study used six marine sediments samples with three times of replication that collected from 16 -36 m water depth. The result shows that there are 28 spesies of benthonic foraminifera characterized by occurences of Amphistegina and Operculina abundantly. Amphistegina radiata is a highest density species that is found in the near shore station. The diversity index is between 1,49 and 2,31 as moderate diversity; evenness index generally is more than 0,6 that indicates stable environment. FORAM index (FI) is more than 4 (6,32 to 9,16) that shows of condusif environmental condition for reef growth.Keywords: community structure, benthonic foraminifera, coral reef, Morotai

Research and Implementation of an IEEE 1588 PTP-Based Time Synchronization System for Chinese Experimental Ocean Observatory Network

With time synchronization becoming an important feature of cabled ocean observatory networks, an innovative approach using the IEEE 1588 standard featuring the precision timing protocol (PTP) is proposed. Both boundary clock (BC) and transparent clock (TC) based on PTP are analyzed, and the framework of a synchronization system mainly consisting of a shore station section, a junction box layer, and a science instrument layer is presented. The proposed time synchronization system was applied and tested on a laboratory setup of the Experimental Underwater Observatory Network System of China. Results indicate that the time accuracy of the proposed system satisfies the needs of the observatory networks either in BC mode or TC mode, and the time accuracy is better in TC mode, especially when the network structure becomes more complex.

Surf Crest Tracking Algorithm in Wave Image

The non-contact ocean wave observation based on shore station could be impacted on high accuracy of surf crest 2D coordinate in wave images. Focus on previous disadvantages such as lower speed and accuracy, a novel surf crest tracking algorithm is represented with crest collapse function which could terminate the tracking process through end point adjustment. The algorithm could not only process the concerned part of the wave image automatically with higher speed, but also record 2D coordinate of every point on the concerned surf crest and the connection between every two contiguous points accurately, which are very practicable in the non-contact ocean wave observation.