Which onboard project am I going to do ?
Project 1: Pseudocalanus in the Arctic: new insight in the ecological niches of two sibling copepod species
This project is held by Dr. Claudia Halsband-Lenk (UNIS)
Background
The copepod genus Pseudocalanus is very common in marine ecosystems of mid- and high latitudes and contributes considerably to plankton biomass in addition to Calanus spp. in the northern hemisphere. It is thus an important component in the marine food web and represents an essential food item for planktivores, such as fish larvae. The genus comprises several species that are difficult to distinguish morphologically, but have substantial overlap in their biogeographic distributions (Frost, 1989). Consequently, in ecological studies dealing with spatial, vertical, and/or seasonal zooplankton distribution it has mostly been referred to as Pseudocalanus spp. (e.g. Walkusz et al., 2003; Pedersen et al., 2005), ignoring potentially significant differences in life strategies and population dynamics of different, co-occurring Pseudocalanus species. Only very few studies distinguish between multiple Pseudocalanus species, at least for the late developmental stages (Falk-Petersen et al., 1999). Bucklin et al. (1999) recently confirmed that P. minutus and P. acuspes can be reliably discriminated with simple, inexpensive PCR protocols, enabling more detailed ecological studies that take sibling species into account. Pairwise comparison of DNA sequences for a specific region of the mitochondrial cytochrome oxidase I (mtCOI) gene showed that P. acuspes from the Baltic Sea and Troms fjord differs to 16% from P. minutus and to 18% from P. elongatus, common in the North Atlantic and North Sea (Bucklin et al., 2003).
Species-specific studies on the life history of Pseudocalanus are scarce (McLaren et al., 1989; Norrbin, 1991). However, after the biology of the large copepod Calanus spp. has been intensively studied in a multi-national, interdisciplinary effort in the 1980’s and 90’s (TASC), several research programs now aim at understanding the dynamics of smaller planktonic species, such as Pseudocalanus, Oithona, and other genera (e.g. GLOBEC), as these often dominate the plankton numerically and sometimes even in terms of biomass, e.g. in coastal areas. As a result, some species-specific information on Pseudocalanus recently emerged: the reproductive biology of Pseudocalanus species has been compared in Alaska (Napp et al., 2005), and population structure, as well as seasonal and vertical distribution were investigated in boreal (Renz & Hirche, 2005) and arctic waters (Lischka & Hagen, 2005). Seasonal data coverage is extremely poor for the Arctic due to inaccessibility of ice-covered areas in winter and spring (but see Werner, 2006).
Svalbard is a perfect place for a comparative study on zooplankton population dynamics, as it is influenced by different water masses and thus represents different biogeographical zones in a relatively small area. Extensive sampling has been performed over the last years and continues around Svalbard, including locations on the Atlantic-influenced west coast, semi-enclosed Spitsbergen fjords, as well as locations in the northeast and to the north towards the marginal ice zone. The goal of this study is to discriminate two Pseudocalanus species in Svalbard waters, P. minutus and P. acuspes, which may occupy quite different ecological niches. Their spatial, vertical, and seasonal distribution patterns in selected locations of Svalbard will be studied in order to gain insight into their population dynamics, and to develop methods that allow discrimination of the sibling species in future studies. To achieve this, both morphological and molecular methods will be applied.
Research Questions
· Which species of Pseudocalanus occur in the Arctic and where?
· How do hydrographic conditions relate to the spatial distribution of Pseudocalanus congeners, with particular regard to P. acuspes?
· How does the distribution of Pseudocalanus congeners differ
a) Horizontally (i.e. regionally)
b) vertically?
c) seasonally?
d) using morphology or molecular markers?
· What can we conclude from the results above about the life strategies of arctic Pseudocalanus congeners?
· What does that mean for future studies on zooplankton distribution?
Work plan
· Sort Pseudocalanus spp. from existing samples in different locations of Svalbard and adjacent waters
· Select stations such that different environmental settings are covered, e.g. total depth, currents (water mass), fjord versus coast, shelf versus open ocean, etc.
· Determine if P. acuspes females occur in addition to P. minutus females (taxonomic key in Frost, 1989) and if yes, in which region(s).
· Analyze potential differences in vertical and seasonal distribution at locations of co-occurrence
· Collect samples in ethanol (ZooGene protocol) and perform comparative mtCOI sequence analysis according to the methods in Bucklin (2000) and Bucklin et al. (1999).
· Develop PCR protocol for discrimination of P. minutus and P. acuspes
· Run Species-specific PCR on samples from different locations
· Analyze species distribution with molecular data and compare with morphology results
For more information on this project please contact Claudia Halsband :
claudia.halsband-lenk@unis.no
Literature
Bucklin, A. (2000) Methods for population genetic analysis of zooplankton, chapter 11. In: The zooplankton methodology manual, International Council for the Exploration of the Sea. Academic, London, pp 533-570
Bucklin, A., Frost, B.W., Bradford-Grieve, J., Allen, L.D., Copley, N.J. (2003) Molecular systematic and phylogenetic assessment of 34 calanoid copepod species of the Calanidae and Clausocalanidae. Marine Biology 142, 333-343
Falk-Petersen, S., Pedersen, G, Kwasniewski, S., Hegseth, E.N., Hop, H. (1999) Spatial distribution and life cycle timing of zooplankton in the marginal ice zone of the Barents Sea during the summer melt season in 1995. Journal of Plankton Research 21(7), 1249-1264
Frost, B.W. (1989) A taxonomy of the marine calanoid copepod genus Pseudocalanus. Canadian Journal of Zoology 67, 525-551
Lischka, S., Hagen, W. (2005) Life histories of the copepods Pseudocalanus minutus, P. acuspes (Calanoida) and Oithona similis (Cyclopoida) in the Arctic Kongsfjorden (Svalbard). Polar Biology 28, 910-921
McLaren, I.A., Laberge, E, Corkett, C.J., Sévigny, J.-M. (1989) Life cycles of four species of Pseudocalanus in Nova Scotia. Canadian Journal of Zoology 67, 552-558
Norrbin, M.F. (1991) Gonad maturation as indication of seasonal cycles for several species of small copepods in the Barents Sea. Polar-Research 10(2), 421-432
Pedersen, S.A., Ribergaard, M.H., Simonsen, C.S. (2005) Micro- and mesozooplankton in Southwest Greenland waters in relation to environmental factors. Journal of Marine Systems 56, 85-112
Renz, J., Hirche, H.-J. (2005) Life cycle of Pseudocalanus acuspes Giesbrecht (Copepoda: Calanoida) in the Central Baltic Sea: I. Seasonal and spatial distribution. Marine Biology 148, 567-580
Walkusz, W., Storemark, K., Skau, T., Gannefors, C., Lundberg, M. (2003) Zooplankton community structure; a comparison of fjords, open water and ice stations in the Svalbard area. Polish Polar Research 24(2), 149-165
Werner, I. (2006) Seasonal dynamics of sub-ice fauna below pack ice in the Arctic (Fram Strait). Deep Sea Research I 53, 294-309
Project 2 : High Arctic Invertebrate Biogeography: Dispersal, Establishment and Survival
This project is held by Maria Luisa Ávila (Phd student, UNIS)
The aim of the project is to better understand key factors which enable invertebrates to colonize
Arctic regions, in particular remote island groups. The project will address the following questions:
1) How colonization of the Arctic has occurred?
2) Which are the main dispersal pathways for Arctic invertebrates?
3) Did glacial refugia exist on Svalbard during last glacial maximum and, if not, which are, or have
been, the source populations for the colonization of High Arctic islands of Svalbard?
4) What is the population interconnectivity at both local and geographic scale?
5) Which adaptations or pre-adaptations enable species to colonize the Arctic?
6) How robust is the current invertebrate fauna of Svalbard to current climate change scenarios?
The project can be divided into three areas: A) biodiversity and population interconnectivity, B) establishment and C) dispersal abilities.
It is hypothesized that the invertebrate fauna on the cold east coast of Svalbard will be influenced by immigration pathways from the east and north east with the prevailing winds and ocean currents in contrast to the south and south westerly currents and winds that dominate the mild west coast. The biodiversity of the soil microarthropod communities will be determined at various locations throughout Svalbard. In addition to traditional species description, genetic studies involving Amplified Fragment Length Polymorphism analyses and mtDNA sequencing are proposed as a way to identify phylogeographical patterns between populations in the Holoarctic. These studies will include likely source populations in Fennoscandia, Greenland, Siberian and Canadian Arctic, thus determining colonization routes and source populations. Those patterns will also let us know whether refugia existed in the High Arctic during the last glacial maximum.
For more information on this project, please contact Maria Luisa Ávila : mariaj1@unis.no
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