The influence of environmental factors on the micro-chemical composition of cephalopod statoliths.

Zumholz, Karsten (2006) The influence of environmental factors on the micro-chemical composition of cephalopod statoliths. Open Access (PhD/ Doctoral thesis), Christian-Albrechts-Universität, Kiel, 86 pp.

[thumbnail of d1605.pdf]
Preview
Text
d1605.pdf - Published Version
Available under License German copyright act UrhG.

Download (2MB)

Abstract

The statoliths of cephalopods are calcified bio mineral structures found in the gravity receptor system in the head of cuttlefish and squid. They grow throughout the lifetime of the animal and deposit microscopically visible daily increments similar to the annual rings in tree stems. Statolith growth and composition are linked to environmental factors. Thus, the statolith reveals the biological history of each individual cephalopod. If a relationship can be established between the composition of a growth layer of the statolith and the ambient water properties, then the statolith chemistry becomes a predictor of the surrounding water chemistry and/or temperature. Provided that statolith material is not altered or resorbed after deposition, the statolith becomes a permanent archive of environmental conditions and may provide information on habitat use, timing of exposure to a pollutant, and timing of migrations. Several micro analytical state-of-the-art techniques have been applied in this thesis to investigate the spatially resolved chemical composition of cephalopod statoliths. Recent applications of these methods include mainly geological samples, which do not contain organic compounds. Therefore a considerable part of this project focussed on adjusting and optimising the respective methods to the analyses of biogenic aragonite intergrown with organic compounds. In this thesis, the influence of different environmental factors on the chemical composition of cephalopod statoliths was investigated. On the basis of laboratory experiments under controlled conditions, it is now possible to qualify the influences of salinity, temperature and diet on the concentrations of several elements in the statoliths. Analytical results indicate that the incorporation of a number of elements is influenced by environmental factors. Barium and iodine appear to be the most suitable indicators for temperature. The incorporation of strontium into cephalopod statoliths, however seems to be influenced to a greater extent by diet than by the surrounding water. This is contradictory to results from corals and fish otoliths, where strontium is a well-established indicator for both temperature and salinity. The suitability of statolith micro-chemistry for field-studies has been proven as well. Statolith trace element compositional zoning reflects very well the life history and ontogenetic habitat-shifts of the boreoatlantic armhook squid Gonatus fabricii. Further, this thesis gives valuable insights into the microstructure of statoliths and the elemental nano-scale distribution in daily increments. For the first time, the application of NanoSIMS NS50 provided distribution patterns of calcium, strontium and sodium in cephalopod statoliths with a spatial resolution of 400nm. The results of this study provide an essential basis for future investigations in the field, probably leading into further understanding of yet unknown migration patterns and spawning grounds of various cephalopod species. Applying these future approaches could establish a consolidated biological knowledge on cephalopod species and stocks, and therefore may contribute to an effective and sustainable management of this both ecologically and economically valuable resource.

Document Type: Thesis (PhD/ Doctoral thesis)
Thesis Advisor: Schnack, Dietrich
Keywords: Statolith, aragonite, Cephalopods, sepia, gonatus, trace elements, synchrotron, NanoSIMS, LA-ICPMS, migrations
Research affiliation: OceanRep > Leibniz-Institut für Meereswissenschaften
OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EV Marine Evolutionary Ecology
Refereed: No
Projects: CephLit
Contribution Number:
Project
Number
CephLit
4522
Date Deposited: 03 Dec 2008 16:52
Last Modified: 17 Jan 2023 08:29
URI: https://oceanrep.geomar.de/id/eprint/5284

Actions (login required)

View Item View Item