Profiles

Sture Hansson

Sture Hansson

Professor

View page in English
Arbetar vid Institutionen för ekologi miljö och botanik
Telefon 08-16 42 48
E-post sture.hansson@su.se
Besöksadress Svante Arrhenius väg 20 A
Rum N 504
Postadress Institutionen för ekologi miljö och botanik 106 91 Stockholm

Publikationer

I urval från Stockholms universitets publikationsdatabas
  • 2016. Sture Hansson. Fisheries Research 179, 351-351
  • 2016. Sture Hansson. Fisheries Research 183, 482-482
  • 2017. Peter T. Euclide, Sture Hansson, Jason D. Stockwell. Hydrobiologia 787 (1), 387-396

    Partial migration, whereby only a portion of a population migrates, has just recently received attention in aquatic systems. Partial diel vertical migration (DVM) has received even less attention but could significantly influence our understanding of trophic interactions and nutrient movement in open water systems. Recent work in the Baltic Sea shows differences in isotope composition between benthic and pelagic Mysis salemaai sampled at night, suggesting that partial DVM may be fixed at the individual level. Historic observations of North American M. diluviana suggest partial DVMin this species, but this behavior has largely been ignored in the literature. We used length, occurrence of gravid females, and body delta C-13, delta N-15, delta S-34, and C:N ratio as markers to test for differences among adult M. diluviana collected from benthic and pelagic habitats at night in Lake Champlain, USA. We found differences in body length and occurrence of gravid females between pelagic- and benthic-caught M. diluviana and differences in C: N between pelagic-and benthic-caught non-gravid individuals, consistent with life stage and body condition hypotheses for partial migration. Partial DVM of M. diluviana could have significant impacts on population assessments which could bias food web models used in basic research and management.

  • 2015. Clare N. Webster (et al.). Marine Biology 162 (7), 1429-1440

    Zooplankton often migrate vertically to deeper dark water during the day to avoid visual predators such as fish, a process which can strengthen benthic-pelagic coupling. In the Gulf of Finland, Baltic Sea, a pronounced hypoxic layer develops when there is an inflow of anoxic bottom water from the Central Baltic Sea, which could be a barrier for vertical migrants. Here, we report an acoustic study of the distributions of crustacean zooplankton (mysid shrimp and the copepod Limnocalanus macrurus), gelatinous zooplankton (Aurelia aurita) and fish. Zooplankton trawl nets were used to ground-truth acoustic data. Vertical profiles of oxygen concentration were taken, and the physiological impact of hypoxia on mysids was investigated using biochemical assays. We hypothesised that the vertical distribution of zooplankton and fish would be significantly affected by vertical heterogeneity of oxygen concentrations because anoxia and hypoxia are known to affect physiology and swimming behaviour. In addition, we hypothesised that mysids present in areas with hypoxia would exhibit a preparatory antioxidant response, protecting them from oxidative damage during migrations. The acoustic data showed peaks of crustacean zooplankton biomass in hypoxic (< 2 mL L-1) and low oxygen (2-4 mL L-1) concentrations (depth > 75 m), whereas fish shoals and A. aurita medusae were found in normoxic (5-6 mL L-1) upper water layers (< 40 m), with individual fish in deeper water excepting that rule. Mysid shrimp from areas with hypoxia had significantly enhanced antioxidant potential compared with conspecifics from areas with no hypoxia and had no significant indications of oxidative damage. We conclude that mysids can protect themselves from oxidative damage, enabling them to inhabit hypoxic water. Our data suggest that hypoxic and low oxygen zones (up to 4 mL L-1) may provide some zooplankton species with a refuge from visual predators such as fish.

Visa alla publikationer av Sture Hansson vid Stockholms universitet

Filer

Senast uppdaterad: 23 oktober 2017

Bokmärk och dela Tipsa