Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2017
Erindi/veggspjald / Talk/poster V64
Höfundar / Authors: Jóhann Garðar Þorbjörnsson (1), Jónína Herdís Ólafsdóttir (1), Jukka Siltanen (2), Kalina Kapralova (2), Sigurður Snorrason (2)
Starfsvettvangur / Affiliations: 1. Hafrannsóknastofnun, 2. Háskóli Íslands
Kynnir / Presenter: Kalina Kapralova, Jónína Herdís Ólafsdóttir, Garðar Þorbjörnsson
While Arctic charr in Thingvallavatn has been extensively studied in the last four decades, observations in the wild have been limited, especially for the two smallest morphs planktivorous (PL) and small benthic (SB). These two morphs have diverged along the limnetic to benthic ecological axis and differ largely in body size, life history characteristics, behavior and parasite fauna. Although their spawning appears to overlap in space and time, SB and PL constitute distinct populations, which suggests effective reproductive barrier(s). The central hypothesis of this investigation is that reproductive isolation between SB and PL charr is partly due to differences in the exact timing of spawning, precise spawning location and/or mating behavior. To investigate the nature of these barriers we are conducting observations in the night by scuba diving and underwater filming in Ólafsdráttur, the largest and best described spawning site in Thingvallavatn. Underwater cameras are mounted on flexible tripods with video lights. To minimize disturbance, the cameras are placed in different areas with high activity and left recording as long as the battery lasts (about 1 hour in the 4-5°C water). This process will be repeated over several dives in various locations during the spawning period. PL have a reputation of being timid so we are prepared to adapt our methods and experiment with different colored underwater light, surface lights, camouflage (only black diving equipment) or even rebreather technology. Our preliminary data indicates that SB and PL utilize the same general area for spawning. However, there might be slight differences in location (PL is observed further offshore and at greater depth) and timing (PL emerge later in the evening than SB).