## 3 State-of-the-Art Review
### Specific Networks, Routing Mechanisms and Algorithms  
To satisfy the requirements for marine environment monitoring systems, researchers have proposed and developed a number of specific networks, routing mechanisms, protocols, and algorithms for WSN-based marine environment monitoring. A WSN-based data collection framework was proposed and developed by [PERSON] _et al._[60] for disaster mitigation and rescue operation. A WSN communication protocol with lower delay and better energy efficiency was proposed for data dissemination from disaster areas. A simulation experiment was conducted to validate the performance of the proposed protocol comparing with the SENDROM system protocol. A group-based underwater wireless sensor network (UWSN) was proposed by [PERSON] _et al._[45] to monitor accurately the amount of fecal waste and uneaten feed deposited on the seabed which can cause the damage of the fauna and flora. The design and development of this underwater WSN took into account several factors: number of sensor nodes, sensor nodes mobility model, distribution of sensor nodes, network topology, and communication technologies. [PERSON] _et al._[47] proposed a multi-layered scalable and adaptive approach of data management for a wireless sensor network. This algorithm consisted of three decision making components: sliding window averaging, local rules and parameter evolution. A single buoy was deployed off Scroby Sands to verify the characteristics of the proposed approach. A WSN framework was proposed by [PERSON] _et al._[61] for environmental monitoring applications. Its highlight is on its network layer design by considering multiple aspects: heterogeneity, service-aware control platform, unified routing and scheduling, network monitoring. A special case study was conducted to demonstrate that the framework can be used to guide how to design a WSN for environment monitoring in the future. [PERSON] _et al._[62] presented a routing algorithm of WSNs for marine oil slick monitoring. They proposed two methods: single relay decision (SRD) and multiple relay decision (MRD) protocols for message routing. The proposed algorithms have more efficient message distribution than single hop and greedy approaches. However, their approach does not consider node mobility, energy harvesting and network scalability. An IEEE 802.15.4-based wireless monitoring system was presented by [PERSON] _et al._[48] to collect pH and temperature parameters in a fish farm. The proposed algorithm used a ZigBee-based routing and the application layer to manage information transmission from the source node to the central coordinator. They designed a sub-layer-based power consumption algorithm to prolong the node lifetime. [PERSON] _et al._[63] proposed an improved WSN MAC protocol for marine environment monitoring to meet the demand of the energy consumption, real-time transmission, bandwidth and reliability. Simulation results show good energy consumption and network throughput abilities. However, the proposed algorithm was not implemented in the actual sensor node to verify its performance. A WSN dedicated dynamic clustering algorithm was presented for oil slicks monitoring by [PERSON] _et al._[64]. It can be applied to a monitoring system adaptively in terms of number of nodes, clustering dynamics, measurement periods, and metric weights to supervise climate conditions. Various parameters are evaluated regarding their influence on the stability of the network clustering algorithm. [PERSON] _et al._[65] proposed a cloud computing-based approach for data processing in disaster monitoring. The proposed approach used a FTR-HTTP based delivery method from remote client to server. [PERSON] _et al._[66] proposed a cooperative hybrid ARQ (C-HARQ) mechanism in solar powered wireless sensor networks to improve energy efficiency and reliability of energy harvesting. They conducted C-HARQ experiments using a Matlab/Simulink-based simulator for networked and embedded systems.