Harmful algal blooms, or HABs, occur nearly every summer along the nation's coasts. Often, the blooms turn the water a deep red. Harmful algal blooms, or HABs, occur when colonies of algae—simple plants that live in the sea and freshwater—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds. The human illnesses caused by HABs, though rare, can be debilitating or even fatal. While many people call these blooms 'red tides,' scientists prefer the term harmful algal bloom. The reports of algal blooms indicate their predominance along the west coast of India, especially the southern part. There have been 39 causative species responsible for blooms, of which Noctiluca scintillans and Trichodesmium erythraeum are the most common. Reporting of massive fish mortality in Indian waters has been associated with the blooming of Cochlodinium polykrikoides, Karenia brevis, Karenia mikimotoi, Noctiluca scintillans, Trichodesmium erythraeum, Trichodesmium thiebautii and Chattonella marina. Most of the blooms occurred during withdrawal of the south–west monsoon and pre–monsoon period. In Indian waters, this process is mainly influenced by seasonal upwelling and monsoonal forcing that causes high riverine discharge resulting in nutrient–enriched waters that provides a competitive edge for blooming of phytoplankton species. Scientists don’t yet know how to predict specific blooms, but generally speaking, algal growth is related to nutrient levels in the water. Excess nitrogen content is often associated with more algae in marine waters, as is excess phosphorus in freshwater. Warmer waters are associated with blooms of toxin-producing cyanobacteria (also known as blue-green algae, although they are, in fact, bacteria); these blooms peak in lakes during summer months.
Details about WSN Needed
The WSN is to be implemented along the shallow coastal areas of the bay. Around 10 km of the Konkan coast is to be monitored during summer for a period of two months. The network covers an area of 2 km into the ocean. Depth of the ocean near the coast usually does not exceed 100 meters. Algae study requires several types of characteristics to be measured. The deployment aims to collect the following information: dissolved oxygen, light (photosynthetic irradiance), pressure, salinity, temperature and turbidity. Sensing range of these nodes is 15 m and the perfect sensing range is 10m.
For further detailed monitoring AUVs (Autonomous Underwater Vehicles are deployed) once a week. These AUVs are equipped with camera with to capture underwater images of the algae bloom. The AUVs operate independently of the WSN.
Data Collection is of three types at (i) Regular Sampling Intervals of 5 Minutes (ii) Irregularity in sensed data may cause remote system to instruct the motes to reduce the sampling interval (iii) There might an on-demand monitoring of certain areas of the ocean – where the bloom is intense from a remote system.
Answer the following questions.
a. What is the deployment pattern - how many motes will be required, are all motes of the same type, classify requirements as motes (sensing, relay, sensing and relay) and super motes, where will you place each mote/super mote? Justify. (Draw and explain Deployment Diagram)
b. For the application scenario - what are the characteristics that the network protocol stack should possess (In terms of energy conservation, processing and memory requirements, fault tolerance, data criticality, real-time operations, tenability, maintenance)?
c. Would a time synchronization Algorithm be required? If so, which one will you use and why?
d. Would a Localization Algorithm be required? If so, which one will you use and why?
e. Is the data collection proactive or reactive or hybrid?
f. Would use Clustering? If so, which algorithm and why? Will this clustering be hierarchal? Justify
g. Which Routing Algorithm will you use and why?
h. Topology Control requirement is necessary- Suggest and explain a protocol that would work ideally in such an environment.
i. What is the addressing method you will use in the WSN, explain with justification?
j. What will be the type of communication that will be used underwater? What are the issues you envisage in communicating underwater?