Interspecific competition between Arctic kelps – a field study

Seaweeds are very important primary producers in coastal ecosystems. Brown algae of the order Laminariales (“kelps”) form three-dimensional habitats, contributing essentially to the structural heterogeneity of the habitat. Kelps have a complex life cycle and it was shown that the reproductive cells and early developmental stages are more vulnerable to changes than the adult sporophytes. Temperature is one of the most fundamental determinants of biological patterns and processes such as growth, reproduction and survival. In the Arctic seawater surface temperatures are modelled to rise between 3-4°C within the next 100 years. Generally, the ongoing and chronic disturbance due to environmental change in the oceanic system of the Arctic are likely to cause changes in ecosystem structure including a loss of polar marine biodiversity.

There is a general lack of experimental designs testing the interplay of abiotic and biotic factors, especially in Polar Regions. To date very little information on interspecific competition between kelps exists. Species, however, do not live in isolation and interspecific competition may strongly affect the recruitment of each species and be possibly altered under a changing environment. This may drive important local-scale changes in community dynamics, biodiversity, and ecosystem functioning, thus potentially leading to altered patterns of distribution and abundance.

In the upcoming season we want to continue competition experiments between kelps that were initiated in 2014 and investigate juvenile kelp sporophytes in field and laboratory experiments. Spores of the two kelp species Alaria esculenta and Saccharina latissima will be seeded on settlement tiles in mixed and unialgal treatments and exposed to 2 different water depths. The development of young sporophytes will be followed mainly through growth and photosynthesis. After 4 weeks half of the experimental units will be removed from the field and exposed to two different temperatures in the laboratory while the rest stays in the field for 8 weeks. The same set-up will be installed in the laboratory mimicking the light regime of the different water depths serving as a control for the field experiment with fixed environmental conditions. Additional laboratory experiments on young sporophytes in the laboratory will be performed.

Objectives and Tasks
The two kelp species are occupying the same habitat and have overlapping fertility times during summer being potential competitors on substrate and other resources. We want to answer 3 major questions:

(1) Will interspecific competition between the species occur and in which way?
(2) Is the outcome of the competition changing under different light and temperature regimes which are changing under global warming?
(3) Are there differences between laboratory and field approaches?

Weitere Informationen

Unternehmen

Helmholtz Gemeinschaft

Bereich/Abteilung

lfred-Wegener Institute, Helmholtz Centre for Polar and Marine Research

Abschlussart

Bachelorarbeit

Branche

Bio- und Gentechnologie

Schlagwörter

interspecific competition Brown algae Laminariales Meeresbiologie Botanik Biologie

Anforderungen

• basic knowledge on marine biology/seaweeds and ecology;
• there is the possibility to accompany a field course in March 2015 to Helgoland (North Sea);
• a scientific diver certificate would be very welcome.

Zusatzinformationen

Time and Location:

Practical field work will take place at the Koldewey station, Ny Alesund, Spitzbergen between July and September 2015. Preparatory work (training on methods) will take place in Bremerhaven between May and June 2015 (dates to be agreed upon); data evaluation after the expedition in the home laboratory, travel expenses will be paid by the Alfred Wegener Institute.

Contact:
Dr. Inka Bartsch, Inka.Bartsch(at)awi.de, 0471 / 4831-1404
Dr. Katharina Zacher, Katharina.Zacher(at)awi.de