Marine Ökologie

From evolutionary genetics to conservation: The Loggerhead Sea Turtle (Caretta caretta) project at the Cape Verde archipelago

PhD student Victor Stiebens. PI Dr. Christophe Eizaguirre

                  

The endangered Loggerhead Sea Turtle boosts the third largest nesting aggregation at the islands of Cape Verde. Despite the high density of Loggerheads still observed, it is now clear that the population declines rapidly. Together with the INDP (Institute for the Development of Fisheries) and several NGO’s (such as Turtle Foundation), we aim to establish robust science based conservation programs. Our aims are three-fold:

i) Understand demographic events shaping the population structure and functioning across the different islands using neutral and adaptive genetic markers. We focus on the genes of the major histocompatibility complex (MHC), which evolve under both natural and sexual selection. These genes are at the root of disease resistance in vertebrates and therefore allow us to anticipate the consequences of possible future disease outbreak in a warmer future ocean;

 ii) The above mentioned methods are all indirect measures to understand population functioning. On a couple of turtles, we deployed satellite transmitters equipped with CTD sensors (Conductivity, Temperature and Depth) and oxygen optodes to get a grip on the habitat turtles live in. Unfortunately such devices can only be mounted on adult and subadults. However, to close the turtles life cycle the question of hatchling dispersal still remains a major mystery in the Cape Verde population. Together with ocean modelers we are working on dispersal models which could, at least in theory, predict where these hatchling and posthatchlings passively drift to.

 iii) Eventually reproductive behavior is the third key gap we aim to fill. Here we address questions of multiple paternity and female based mate choice (again using the MHC genes). Satellite data will also hopefully give import insight in the turtles mating grounds.

Want to volunteer in a great turtle project? Visit: http://turtle-foundation.org/

Any questions?  Contacts:  vstiebens(at)geomar.de or ceizaguirre(at)geomar.de  

The return of the houtings: conservation genetics and ecology of anadromous whitefishes in Germany

The whitefish project aims to answer applied and fundamental questions related to the near-extinction and current reexpansion of the endangered anadromous North Sea houting (NSH) and Baltic houting (BH) (alternatively classified as the separate species Coregonus oxyrinchus and C. lavaretus or as different varieties of C. maraena). These taxa have a turbulent conservation history in Germany. Once important fisheries species, construction of migration barriers and habitat loss led to their local extinction (NSH) or near-extinction (BH) by the 1960s. Stocking with NSH from the last remnant population in the Danish river Vida in 1987 then led to the reintroduction in the German Treene River, which subsequently served as stepping stone for stocking of the rivers Elbe and Rhine (North Sea drainage). Similarly, BH was reintroduced from a refuge Baltic population to rivers draining into the Baltic Sea.

Over the past two and a half years, this project has provided the first biological baseline study of these populations (Figure 1), both to assist resource managers to make informed decisions in conservation programs, and to understand evolutionary consequences of reintroductions and stocking programs.

Genetic tools applied in this study include microsatellite analysis and mtDNA analysis, as well as 454-sequencing of genes of the major histocompatibility complex (MHC). Ecological tools include stable isotope analysis, otolith microchemistry, morphometrics, and standard fish biology measures.

 

The whitefish work has been a collaboration of Dr. Chris Eizaguirre (EV) and Dr. Jan Dierking (EV), with numerous other scientists providing additional samples, data and support (most notably, Kim Praebel, University of Tromsoe, Jost Borcherding, University of Cologne, and Matthias Brunke of the German Landesamt für Landwirtschaft, Umwelt und Ländliche Räume (LLUR)). It has been funded by the LLUR and the Fishery Society of the British Isles, and would not have been possible without the voluntary support from a great number of field helpers, fishermen, and conservation groups.

 

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