20. December 2017 Squid as links within and between foodwebs

A specimen of the atlantic squid Sthenoteuthis pteropus. Photo: Solvin Zankl, www.solvinzankl.com

New details published on the role of squids in the oceanic food web and carbon cycle

Squids are marine animals with fascinating biological characteristics. Some produce light, they have good eyes, they occur from reefs to the deep sea, some of them are fast swimmers. But the knowledge about the way of living of many species and their role in the ocean system is still very fragmented. Two new studies by researchers from the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Kiel Cluster of Excellence "The Future Ocean" show that the role of squids as predators and carbon transporters is important.

 

(Joint press release of the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Kiel cluster of excellence "The Future Ocean")

Squids and octopuses have always attracted the attention of mankind. In past centuries, sailors considered them as sea monsters. Today, scientists are fascinated by their intelligence and their physical abilities. Nevertheless, surprisingly little is known about most squid species and their ways of living, in particular in the open ocean and the deep sea.

Scientists from the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Kiel Cluster of Excellence "The Future Ocean" have now published two studies that reveal new details on the role of squid in different parts of the ocean system. In a paper published recently in the journal PLOS ONE, the biologists analyze the feeding habits of the oceanic squid Sthenoteuthis pteropus from the tropical Atlantic for the first time in detail. The second study, published in the Proceedings of the Royal Society B, deals with the role of Pacific squids as transmitters of carbon to the deep seafloor.

"What both studies have in common is that they give clear indications that squids have important roles in the oceanic ecosystem during different parts of their life cycle," says Dr. Henk-Jan Hoving from GEOMAR, who is author of both papers.

In order to investigate the position of Sthenotheutis pteropus in the food web of the tropical Atlantic, the researchers had caught a total of 129 specimens in 2015 during three expeditions with the German research vessels METEOR and MARIA S. MERIAN. Afterwards, they examined the stomach contents and analyzed stable isotopes ratios in muscle tissue and in the gladius, a chitinous 'backbone' of the squids. The latter grows with the individual and hence can be used to obtain information on feeding environment and feeding habits throughout the squid's life. "Specific isotope ratios of muscle tissue allow estimations on the trophic level of an animal," explains Veronique Merten, biologist from GEOMAR and first author of the PLOS ONE study.

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