Other Collaborative Projects

Temperature & Pollution affecting stress tolerance in marine invertebrates

This project is in collaboration with Dr. Inna Sokolova from the University of North Carolina at Charlotte.

Little is known how changes in environmental parameters, especially in combination, affect stress tolerance and, therefore, survival of ectotherms. Due to anthropogenic impact, environmental changes happen rapidly leaving insufficient time for evolutionary adaptation. Thus, the survival and distribution of species on the population level in a changing environment will depend on their abilities to cope with stress by metabolic adjustments.

The project focuses on the combined effects of environmental temperature (such as expected in future scenarios) and heavy metals on bioenergetics of oyster. Although most intertidal organisms, and especially sedentary ones like oysters, have developed mechanisms for dealing with fluctuations in environmental parameters (e.g. temperature, hypoxia, salinity) their ecosystem is the one mostly affected by global change and human activity. We use experimental and comparative approaches in order to determine and understand stressor-induced changes in energy metabolism from the molecular via cellular to the organismic level; e.g. by in vivo MRI measurements.

Contact Investigator

Dr. Gisela Lannig

Dr. Christian Bock

The cellular basis of standard and active metabolic rate in the free-swimming cephalopod, Sepia officinalis

In cooperation with the Department of Zoology, University of Cambridge, England (NERC NER/A/S/2002/00812, PI: R.G. Boutilier†)

Cephalopods are the largest, most active invertebrates and there is considerable evidence for their convergent evolution with fishes. However, most active cephalopods display standard and active metabolic rates that are several-fold higher than comparably sized fishes. Prediction of the probable outcome of cephalopod-fish competition therefore requires quantitative information concerning whole animal energetics and corresponding efficiencies. Migrating cephalopods such as squid and cuttlefish grow rapidly to maturity, carry few food reserves and have little overlap of generations. This "live fast, die young" life history strategy means that they require niches capable of sustaining high power requirements and rapid growth. These niche are also defined by ambient temperature conditions (e.g. Melzner et al 2006)

This project sets out to investigate the cellular basis of energy metabolism in the cuttlefish Sepia officinalis, based on laboratory experiments and field data. We use field tracking data in combination with lab based respirometry and video analysis to investigate diurnal activity patterns to assess the proportionality of standard vs active metabolic rate and the daily energetic requirements. Effects of environmental temperature on mitochondrial energy coupling are investigated in whole animals using in vivo 31P-NMR spectroscopy and in isolated mitochondria by measuring mitochondrial membrane potentials.
Efficient energy turnover needs sufficient oxygen supply, we therefore also investigate thermal effects on blood oxygen-binding capacities of the respiratory pigment haemocyanin and on the differential expression of its isoforms in a panmictic population (Wolfram et al., 2006).

Contact Investigators

Dr. Felix Mark

EU Project CENSOR: Climate variability and El Niño Southern Oscillation: Implications for natural coastal resources and management

: Distribution range of crustacean species. To understand distribution limits of commercially important decapod species, and the possible geographical shifts due to changes in temperature we analysed two Galatheidae (Anomura) crabs: Munida gregaria (orange line) and Pleuroncodes monodon (grey line) and one brachyuran crab: Cancer setosus (blue line). Both groups are being studied in different locations of their latitudinal distribution, as climate changes will have opposite effects on populations at the northern and southern edges of their distribution. Populations are not only challenged by short-term changes such as El Niño, but also by long-term changes such as to global warming (modified after Avalos et al. 2005).

Background:

Marine biodiversity and the sustained exploitation of marine resources are significantly influenced by ENSO (El Niño-Southern Oscillation) particularly affecting the coastal zone of the Humboldt Current upwelling system. Both its warm (El Niño: EN) and cold (La Niña: LN) phases generate different challenges for the local ecology, socioeconomy and infrastructure. Studies of coastal ecosystems in the Humbodt current system off South America traditionally have been rather descriptive. Data acquisition on macrobenthic communities and/or the pelagic regime over time revealed changes in e.g. abundance, biomass and biotic composition related to ENSO. However, ecophysiological processes underlying these pattern remain principally undefined. Such knowledge is required to explain diversity and biogeographic shifts, changes in growth patterns and reproductive traits related to ENSO.
Within Workpackage 3 (“Ecophysiolocial constraints and aquacultural demands”) of the EU funded CENSOR project we attempt to improve the understanding of ecophysiological demands explaining shifts in resource availability, aiming at a better management of fisheries. Only a profound knowledge and understanding of the functioning of coastal communities and ecosystems under extreme stress as during EN can help to develop recommendations and advices to manage natural and aquacultural marine resources impacted by recent climate oscillation.

: Growth model for Cancer larvae. Temperature is one of the crucial environmental factors setting the limits for life, influencing the activity of organisms including the rates of growth. We reared Cancer larvae at different temperatures and measured larval growth (increase of biomass in µg carbon). The multiple linear model will help us understand how climatic changes (global warming, El Niño) influence survival and fitness of the larval stage (Weiß et al., submitted).

Research topics:

Determination of thermal limits and energy budgets

Temperature changes can affect, directly or indirectly, marine populations during all life stages (Urban 1994, Pörtner 2001). In order to understand the distribution limits of the selected species, the stress thresholds for temperature changes will be identified (Sommer & Pörtner 1999, Zielinski & Pörtner 1997) and interpreted in relation to the natural distribution of species (Anger et al. 2003). The determination of thermal tolerance windows during larval development and adult growth of selected key species from plankton and benthos (e.g. Argopecten purpuratus, Fissurella sp., Loxechinus albus, Homalaspis plana, Platycanthus orbignyi, Cancer setosus, Xiphopenaeus riveti, Pleuroncodes monodon) will help directly to explain and predict survival and biogeographic shifts of these organisms in the field. It will also yield information on optimal temperature set-ups in aquaculture facilities.

Early life histories

Understanding early life history in key species is the first step towards fishery and recruitment management as well as successful aquaculture. We study early life history traits of invertebrates (molluscs and crustaceans) under controlled laboratory conditions. On the one hand, early life history studies of both holoplanktonic organisms and benthic invertebrates will facilitate aquaculture by optimal design of food and rearing conditions. On the other hand, early life history traits analysed in the laboratory (invertebrate larvae, fishes and holoplankton organisms) will help to identify and study key-species (commercial or indicator species) from the water column and facilitate ecological work. Utilizing molecular and physiological tools, we will explore how genetic variability within populations affects the plasticity in ecophysiological adaptations to ENSO, which may be dependent on the intensity of evolutionary driving forces (shifts in e.g. temperature, food availability, salinity) that such populations are exposed to. Comparing life history data obtained from laboratory work with patterns found in nature shall help to predict changes in the marine realm due to ENSO. Finally these changes may also serve as model cases for global change scenarios. Reproductive failures or mass mortalities of certain species versus reproductive success or mass recruitment of others will be key processes during global warming.