Introduction

Diary

Participants

 

R/V Pelagia Cruise HERMIONE /CoralFISH
	Diary overview
Monday, 2 November	Rachel making a slurry for the algae dump experiment...
Early in the morning we beep the mooring. It immediately answers that it is 3058m away from the ship, which means that it is almost straight down below us. We will try to pick it up in the afternoon. First we want to redo our spinach experiments from last year at this station. We had the crazy idea to offer the scavenging fish of the deep-sea some fresh spinach. Spinach was attached to our lander and a time-lapse camera recorded any uninvited guests. This resulted in the surprising and astonishing find that especially the rattail fish were very fond of it. They ripped the nylon stockings in which the Iglo frozen blocks of spinach were packed to pieces to eat the contents. Now we have the Aberdeen lander on board, which is specially designed to record scavenging fish.
And as Thom is willing to deploy his lander with spinach instead of the usual mackerel, we hope to duplicate and strengthen our findings of last year. In preparing his lander Thom noticed at least one advantage as spinach is easier and less messy to handle as a thawing mackerel and it doesn't smell as bad. In beautiful sunny weather the Aberdeen lander was easily deployed. In the mean time the ALBEX lander was also prepared for another baited experiment. Instead of spinach we want to offer the fish material that is more natural. We learned from former projects that the algae springbloom in the surface waters can sink quite quickly to the deep-sea bottom to form a green matt that sometimes can be more than 1 cm thick.   So we try to mimick this by dumping green unicellular algae on the seafloor ourselves. We designed a device that can do this and have attached this to our lander. Again a camera will record what will happen. Deploying the lander in this nice weather is a matter of a few minutes. In the afternoon the BIOFUN mooring is released and it indeed confirms that it is on its way to the surface. The whole ascent of the mooring will take about 50 minutes. At the right time a bunch of people is standing on the bridge to try to spot it. Again I am the first to spot it, and again I don't see the flag! Arie and Lorendz have experience, and together with Erwin who is steering the ship, they manage to catch the mooring after only a few trials. Again all equipment is recovered safely and again all equipment worked very well. But the top part of the mooring is gone and is drifting somewhere in the ocean. We haven't found the cause, but the eroded iron chains at the top of the mooring show that seawater can be very agressive for metals.   Marc Lavaleye