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Anders Nilsson

Professor | PhD

If it moves it’s potentially interesting! I’m an aquatic ecologist with a behavioural ecological background. My approach to research often focuses on individual animal behavioural decision, performance and success, and generally aims to address higher-order consequences and conservation aspects of these behavioural attributes. Current research interests include 


Avian predation as ecological selection on fish phenotypes


Photos: Aron Hejdström, Jim Almond, own

Evaluating how predation exerts ecological selection on phenotypes in the wild is inherently difficult, as it needs information on the predation fate of individual prey in a natural setting. In this project, we tag phenotypically evaluated fish with passive integrated transponders (PIT), and release them into their home lakes. Cormorants naturally predate on fish in lakes, and after foraging they return to nearby roosting trees to dry their feathers and digest food. They also regurgitate indigestible prey body parts, including PIT tags, why scanning the ground below the trees identifies cormorant-predated individual phenotypes. We use this unique system to evaluate how fish e.g. species, morphologies, hybrids, personalities and sensory capacities affect the probability of cormorant predation in the wild, in pursuit of patterns and mechanisms behind ecological selection.

Selected publications:

  • Skov C., Chapman B.B., Baktoft H., Brodersen J., Brönmark C., Hansson L-A., Hulthén K., Nilsson P.A., 2013, Migration confers survival benefits against avian predators for partially migratory freshwater fish, Biol Lett 9:20121178.
  • Hulthén K., Chapman B.B., Nilsson P.A., Hansson L-A., Skov C., Brodersen J., Vinterstare J., Brönmark C., 2017, A predation cost to bold fish in the wild, Sci Rep 7:1239,
  • Nilsson P.A., Hulthén K., Chapman B.B., Hansson L-A., Brodersen J., Baktoft, H., Vinterstare J., Brönmark C., Skov C., 2017, Species integrity enhanced by a predation cost to hybrids in the wild, Biol Lett 13:20170208.

Host-parasite interactions


This project deals with interactions between fish hosts and mussel parasitic larvae in streams. Mussel larvae (glochidia) are ectoparasites on fish before they transform into juvenile mussels and fall of their hosts to bury in the stream sediment. Many freshwater mussels are threatened or locally extinct, and availability of suitable fish hosts for glochidia is pivotal for recruitment. We study e.g. host specificity in glochidia, glochidia growth and survival on different hosts, transferability of glochidia between streams and their fish assemblages (for reintroduction purposes), possible effects of parasites on fish, and habitat composition and suitability for fish and mussels.

Selected publications:

  • Schneider L.D., Nilsson P.A., Höjesjö J., Österling E.M., 2019, Effects of mussel and host fish density on reproduction potential of a threatened unionid mussel: prioritization of conservation locations in management trade-offs, Biodivers Conserv 28:259-273
  • Schneider L.D., Nilsson P.A., Österling E.M., 2018, Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus, Hydrobiologia 810(1):283-293,
  • Schneider L.D., Nilsson P.A., Höjesjö, J., Österling M., 2017, Local adaptation studies and conservation: parasite-host interactions between the endangered freshwater mussel Unio crassus and its host fish, Aquat Conserv Mar Freshw Ecosys 27:1261-1269,

Compromised solutions for hydropower and Atlantic eel and salmon

Bypassing Atlantic eel

Video: Olle Calles

Hydropower produces green energy, but reduces connectivity in rivers, with negative consequences for fish life-histories that include migration between freshwater and ocean systems. Eel and salmon undertake such migrations; eel migrate to freshwater habitats for growth and return to the sea to spawn, while salmon spawn in freshwater and migrate to the sea for foraging and growth opportunity. We collaborate with the hydropower industry to find passage solutions for both up- and downstream migration past migration barriers, and also evaluate distribution patterns and habitat restoration best practises for Atlantic eel and salmon.

Selected publications:

  • Degerman E., Tamario C.,, Watz J., Nilsson P.A., Calles O., Occurrence and habitat use of European eel (Anguilla anguilla) in running waters: lessons for improved monitoring, habitat restoration and stocking, Aquat Ecol accepted
  • Tamario C., Calles O., Watz J., Nilsson P.A., Degerman E., 2019, Coastal river connectivity and the distribution of ascending juvenile European eel (Anguilla anguilla L.) – implications for management strategies regarding fish passage solutions, Aquat Conserv: Mar Freshw Ecosyst 29:612-622
  • Watz, J., Nilsson P.A., Degerman E., Tamario C., Calles O., Climbing the ladder: upstream passage solutions for critically endangered eels require functioning climbing substratum and optimal placement at migration barriers, Anim Conserv
  • Watz J., Elghagen J., Nilsson P.A., Calles O., 2017, Evaluation of a novel mobile floating trap for collecting migrating juvenile eels (Anguilla anguilla L.) in rivers, Fish Manag Ecol 24:512-514.
  • Nyqvist D., Nilsson P.A., Alenäs I., Christiansson J., Hedbrandt M., Karlsson S., Kläppe S., Calles O., 2017, Upstream and downstream passage of migrating adult Atlantic salmon: remedial measures improve passage performance at a hydropower dam, Ecol Eng, 102:331-343.

Hybridization and speciation in mosquitofish


Photos: Brian Langerhans

The Bahamas blue holes are vertical caves filled with water, that have been colonized by the Bahamas mosquitofish. Some of these isolated blue holes also contain piscivorous bigmouth sleepers, and mosquitofish populations have diverged behaviourally and morphologically according to allopatry and predation regime. We evaluate probability of hybridisation between different populations and also hybrid viability, detecting early signs and mechanisms of speciation processes.

Individual movement in a landscape of fear

Most animals trade off growth opportunity against predation risk in behavioural decisions, and the spatio-temporal landscape of this tradeoff should affect prey behaviours. In a recently launched project, where we combine a unique pond infrastructure (iPonds) with high-resolution acoustic telemetry, we study how e.g. animal personality, pharmaceuticals, predator/prey and food distribution, habitat composition, and diel cycles affect spatiotemporal fish behaviour in the physical and chemical landscape of fear. In the clip above, piscivorous pike are blue and prey roach are yellow. Note the marked change in cohesion at dawn around 6am.

Physiological tradeoffs and processes behind inducible defences

Schematic image of carp experiment.

The fascinating crucian carp, Carassius carassius, reacts to chemical cues emitted by predatory fish by growing a deeper bodied morphology; a predator-induced morphological defence. In our present research we use the unique crucian carp model system to challenge fundamental and exciting research questions, including the proximate, physiological mechanisms behind inducible defences (especially the stress axis and the importance of cortisol), how multiple defence traits combine to produce an adaptive, integrated phenotype and how environmental heterogeneity drives plasticity vs. canalization of defence traits.

Selected publications:

  • Vinterstare J., Hulthén K., Nilsson P.A., Nilsson Sköld H., Brönmark, C., Experimental manipulation of perceived predation risk and cortisol generate contrasting trait trajectories in morphology and colouration of phenotypically plastic crucian carp, J Exp Biol
  • Vinterstare J., Hegeman A., Nilsson P.A., Hulthén K., Brönmark C., 2019, Defence versus defence: are crucian carp trading off immune function against predator-induced morphology?, J Anim Ecol 88:1510-1521.
  • Hulthén K., Chapman B.B., Nilsson P.A., Hollander J., Brönmark C., 2014, Express yourself: bold individuals induce enhanced morphological defences, Proc Roy Soc B 281:20132703.

Harbour porpoise behavioural and predator-prey interactions

Cruising harbour porpoise

Video: Per Carlsson

Harbour porpoises are regularly sited in Swedish/Danish coastal waters, while surprisingly little is known about their spatio-temporal distribution patterns and interactions with conspecifics and prey. We study behavioural cascades from zooplankton to fish to porpoise spatio-temporal distribution patterns, monitor aspects of porpoise social foraging behaviour, and porpoise responses to recreational motorboating, to enhance our understanding of harbour porpoise prerequisites and protection.

Using eDNA to study invasive round goby


Photo: Jörgen Wiklund

A recently initiated project develops behavioural assays and eDNA methods to monitor invasive round goby dispersal and distribution patterns in coastal waters. Originally from the ponto-caspian region, round goby have been introduced to the Baltic Sea via ship ballast water, and has established and spread, causing threats to local communities by forming dense populations and competing with local fish for food and eating their eggs. Surveys of round goby behaviour, distribution patterns, source populations and invasion fronts intend to increase our understanding of round goby biology and in extension contribute to the reduction of spread.

Selected publications:

  • Behrens J.W, von Friesen L.W., Brodin T., Ericsson P., Hirsch P.E., Persson A, Sundelin A., van Deurs M., Nilsson P.A., 2020, Personality- and size-related metabolic performance in round goby (Neogobius melanostomus), Physiol Behav 215:112777,

Biology and ecology of pike


Selected publications:

  • van Deurs M., Andersson A., Vinterstare J., Didenko A., Persson A., Brönmark C., Nilsson P.A., 2017, Using accelerometry to quantify prey attack and handling behaviours in pike Esox lucius, J Fish Biol 90:2462-2469,
  • Stålhammar M., Fränstam T., Lindström J., Höjesjö J., Arlinghaus R., Nilsson P.A., 2014, Effects of lure type, fish size and water temperature on hooking location and bleeding in northern pike (Esox lucius) angled in the Baltic sea, Fish Res 157:164-169.
  • Nilsson P.A., Baktoft H., Boel M., Meier K., Jacobsen L., Rokkjær E.M., Clausen T., Skov C., 2012, Visibility conditions and diel period affect small-scale spatio-temporal behaviour of pike (Esox lucius L.) in the absence of prey and conspecifics, J Fish Biol, 80:2384-2389.
  • Stålhammar M., Linderfalk R., Brönmark C., Arlinghaus R., Nilsson P.A., 2012, The impact of catch-and-release on the foraging behaviour of pike (Esox lucius) when released alone or into groups, Fish Res, 125-126:51-56.
  • Nilsson P.A., Jacobsen L., Berg S., Skov C., 2009, Environmental conditions and intraspecific interference: unexpected effects of turbidity on pike (Esox lucius) foraging. Ethology 115:33-38.
  • Nilsson P.A., 2006, Avoid your neighbours: size-determined spatial distribution patterns among northern pike individuals, Oikos 113:251-258.


Retrieved from Lund University's publications database



Retrieved from Lund University's publications database



Retrieved from Lund University's publications database

Page Manager:
Anders Nilsson
E-mail: anders [dot] nilsson [at] biol [dot] lu [dot] se


Division aquatic ecology

+46 46 222 83 65

+46 70 346 25 66




Aquatic Ecology


Research group

Aquatic Ecology


Doctoral students and postdocs

Main supervisor

Varpu Pärssinen

Assistant supervisor

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