Research Interests
I have broad interests in zooplankton ecology and behavior. What do plankton do? How, why and when do they employ different strategies? How does the physical environment and morphology constrain behavior? How does risk shape life history traits? What are the implications of small scale individual (inter)actions and for larger scale phenomena such as predator-prey interactions, population dynamics, community structure or pelagic flux? How does disease and parasite load impact zooplankton?
Google scholar
Teaching
Researchers and post docs
PhD students
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Lasse Eliassen Parasites in pelagic ecosystems (main advisor)
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Even Sletteng Garvang ´Investigating parasites of copepods with molecular methods´ (main advisor)
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Tora Olsen. ´Evolution of life history strategies and variation associated with migration of marine fishes in the Barents Sea´ (Co-advisor)
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Simon Hasselø Kline ´Seasonal dynamics of the protist community in the Oslofjord and Skagerrak´ (Co-advisor)
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Isabelle Ewers ´Protistan parasite diversity in and near Norwegian fish farms´. (Co-advisor)
Former PhD students
Tags:
Ecology,
Marine ecology,
Pelagic ecology,
Behavioral ecology,
Plankton,
Zooplankton,
Jellyfish
Publications
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Vereide, Emilie Hernes; Mihaljevic, Marina; Browman, Howard; Fields, David M.; Agersted, Mette Dalgaard & Titelman, Josefin
[Show all 7 contributors for this article]
(2023).
Effects of airgun discharges used in seismic surveys on development and mortality in nauplii of the copepod Acartia tonsa.
Environmental Pollution.
ISSN 1566-0745.
327.
doi:
10.1016/j.envpol.2023.121469.
Full text in Research Archive
Show summary
Seismic surveys are conducted worldwide to explore for oil and gas deposits and to map subsea formations. The airguns used in these surveys emit low-frequency sound waves. Studies on zooplankton responses to airguns report a range of effects, from none to substantial mortality. A field experiment was conducted to assess mortality and naupliar body length of the calanoid copepod Acartia tonsa when exposed to the discharge of two 40-inch airguns. Nauplii were placed in plastic bags and attached to a line at a depth of 6 m. For each treatment, three bags of nauplii were exposed to one of three treatments for 2.5 h: Airgun array discharge, a boat control, or a silent control. After exposure, nauplii were kept in filtered seawater in the laboratory without food. Immediate mortality in the nauplii was approximately 14% compared to less than 4% in the silent and boat control. Similarly, there was higher mortality in the airgun exposed nauplii up to six days after exposure compared to the control treatments. Nearly all of the airgun exposed nauplii were dead after four days, while >50% of the nauplii in the control treatments were alive at six days post-exposure. There was an interaction between treatment and time on naupliar body length, indicating lower growth in the nauplii exposed to the airgun discharge (growth rates after 4 days: 1.7, 5.4, and 6.1 μm d−1 in the airgun exposed, silent control, and boat control, respectively). These experiments indicate that the output of two small airguns affected mortality and growth of the naupliar stages of Acartia tonsa in close vicinity to the array.
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Vereide, Emilie Hernes; de Jong, Karen; Mihaljevic, Marina; Fields, David M.; Titelman, Josefin & Browman, Howard
[Show all 9 contributors for this article]
(2023).
ZoopSeis- The effects of seismic surveys on zooplankton .
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Vereide, Emilie Hernes; de Jong, Karen; Titelman, Josefin; Browman, Howard; Agersted, Mette Dalgaard & Mihaljevic, Marina
[Show all 7 contributors for this article]
(2022).
Seismikkens påvirkning på dyreplankton.
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Vereide, Emilie Hernes; de Jong, Karen; Titelman, Josefin; Browman, Howard; Agersted, Mette Dalgaard & Mihaljevic, Marina
[Show all 7 contributors for this article]
(2022).
The Effects of Seismic Surveys on Zooplankton – Small animals meet loud noise.
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Vereide, Emilie Hernes; de Jong, Karen; Titelman, Josefin; Browman, Howard; Fields, David M. & Agersted, Mette Dalgaard
[Show all 7 contributors for this article]
(2022).
Impacts of Airgun Blasts Used in Seismic Surveys - Small Effects in Small Copepods.
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Vereide, Emilie Hernes; de Jong, Karen; Titelman, Josefin; Browman, Howard; Fields, David M. & Agersted, Mette Dalgaard
[Show all 7 contributors for this article]
(2022).
Impacts of Airgun Blasts Used in Seismic Surveys - Small Effects in Small Copepods
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Tran, Jacquelynn Phuong-Vy; Edvardsen, Bente; Fon, Mathias; Heuschele, Jan David & Titelman, Josefin
(2023).
When hungry meets harmful: investigating the toxic relationship between haptophytes and copepods. Predatory induced defenses in Chrysochromulina leadbeateri. .
Universitetet i Oslo.
Show summary
Harmful algal blooms are a recurring phenomenon all around the world, causing devastating effects including massive fish kills. A bloom of the toxic haptophyte, Chrysochromulina leadbeateri, in Northern Norway during May-June 2019 was the largest bloom ever recorded in that area causing massive mortalities of farmed salmon. While past C. leadbeateri blooms are known to cause such damage, relatively little is known about this toxic haptophyte, compared to other species. Some studies have investigated the bloom dynamics and abiotic factors influencing its toxicity, but little is known about the biotic influences. In particular, the predator-prey interactions with copepods. Past studies have found that when other species are directly exposed to predation threats (e.g. herbivorous copepods), the algae will respond by inducing and/or increasing toxicity potential as a defense mechanism. Those studies have focused on toxic diatoms and dinoflagellates producing shellfish toxins, but the potential for fish-killing algae to be influenced by predation pressure remains to be explored. In this thesis, I examined the biotic interactions between the toxic C. leadbeateri and the grazing Acartia sp. copepods. I first conducted a series of 3-day tolerance experiments, exposing Acartia sp. to different C. leadbeateri concentrations to answer: What is the threshold C. leadbeateri concentration that Acartia sp. can maintain survival and grazing? Then I conducted 3-day induction experiments, exposing C. leadbeateri to varying levels of grazing pressure, and in vitro tests using two fish cell lines to measure this potential grazing-induced toxicity to answer: Does the presence of copepod grazers affect toxicity in the ichthyotoxic haptophyte C. leadbeateri? Through the initial tolerance experiments, I determined that ca. 5 x 104 cells ml-1 of C. leadbeateri was the threshold concentration that enough Acartia sp. could survive and maintain feeding for the later toxicity induction experiments. Acartia sp. short-term tolerance to direct exposure to C. leadbeateri appeared to be concentration and time-dependent since the toxins need to be taken up by Acartia sp. to cause mortalities. Copepod grazing habits observed during the induction experiment appeared unaffected when C. leadbeateri was the only food source, as evidenced by fecal pellet production. However to accurately determine the effects of grazing on C. leadbeateri, future studies should observe grazing periodically with Acartia sp. exposed to different C. leadbeateri concentrations and non-toxic food alternatives. I examined whether the toxicity of C. leadbeateri was influenced by the presence of grazing copepods using in vitro tests on two fish (Rainbow trout and Atlantic salmon) cell lines to measure cell viability and light microscopy to look at morphological changes. I created different concentrations of algal extracts from crude C. leadbeateri material exposed to varying grazing levels. The different extracts were exposed to the gill cells in a microplate-based assay for 24 hours and at the endpoint, cell viability was measured using Alamar blue as an indicator dye. It seems that while increasing algal extract concentration decreases cell viability, extract made from C. leadbeateri exposed to increasing grazing pressure does not increase the negative effects on cell viability. The light micrographs of the gill cells suggest the same, but with some inclination that grazing pressure does affect some toxicity potential in C. leadbeateri. Unfortunately, with the lack of more independent trials, there is no statistical analyses to back up these claims. More experiments would allow for proper analyses and a potentially more conclusive statement about the relationship between copepod grazing and the toxicity potential of C. leadbeateri. This thesis can be used as a starting point for future research on the dynamics between toxic haptophytes and their copepod grazers.
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Published
Nov. 3, 2010 3:34 PM
- Last modified
May 31, 2024 4:54 PM
