The Fourth Week

Yesterday produced an all-time record tow which included 75 identified taxa (the species count was surely higher but not all specimens could be identified to that level). This was the largest number of taxa recorded in the entire Nansen database of 33000+ survey stations. The total catch was modest, less than 140kg, but it included 5 species of carangid, 4 clupeids, 3 engraulids and 7 species of shrimp while the single largest catch (numbers and weight) was a catfish (Plicofollis (Arius) tenuispinis). Overall the survey has recorded 271 distinct taxa to date, although not all are identified to the species level.
At the request of the National Institute of Oceanography the survey has included several nights of multibeam mapping in the swatch (Indus River submarine canyon). These data will be combined with the existing multibeam datasets at the NIO to extend the 3D mapping of this striking submarine canyon

Oceanography and O2

Teams of four oceanographers from the National Institute of Oceanography are participating in the demersal and pelagic surveys. They are collecting in-situ observations of water (Salinity, Oxygen, Nutrients, Chlorophyll) and plankton (phyto and zoo) samples from the shelf and deep waters of the roughly 240,000 sq. km in the Pakistan Exclusive Economic Zone. The samples collected will be analyzed onshore at the National Institute of Oceanography and will be shared with collaborators.

This program provides a unique opportunity of national and international collaboration and features a multi-disciplinary aspect of ocean science and its applications.

The Arabian Sea constitutes one of the world’s most unique and complex oceanographic regions and is ranked one of the most biologically productive areas. Some of its characteristic features include the two monsoons resulting in wind and water circulation reversal from winter to summer; upwelling-“up-slopping”, and a highly complex oxygen minimum zone etc. All these and more have a distinctive influence on the biological productivity of the Pakistani waters.

Oceanographic results from this survey will be used to address questions such as:

• Variability of the deep O2 minimum: physics or biology? Which regulates or is regulated by this feature?
• Chlorophyll a to predict the production zone and its connectivity with the fish potential- using ground observations and remote sensing
• Climatic and seasonal variability in zooplankton productivity over the last two decades (1992-2010), special emphasis to ichthyo-plankton and cephalopod paralarvae- connection to fishery production
• Diversity maps for plankton- deep and coastal waters of Pakistan.
• Fill in some of the gaps in the data from the earlier oceanographic programs, repeat sampling at some of the historic stations.
• Update the national oceanography data bank.