Predation by Oithona spp. on protozooplankton in the Ross Sea, Antarctica

Krill larvae, copepods and the microbial food web: interactions during the Antarctic fall

“…In contrast to most other studies, we investigated the ciliate community with a high enough taxonomic resolution to discern grazing effects on individual taxa. The rate we measured for Oithona's grazing on vulnerable ciliates (Table 5) was similar to that measured previously for total ciliates by both Atikinson (1996) and Nakamura & Turner (1997), but only a third of that measured by Lonsdale et al (2000). In our experiment, the grazingvulnerable ciliates were small (maximum dimension ≤ 21 µm), and larger ciliates common in our experiments such as Strombidium acutum and Leegaardiella ovalis were not grazed, running counter to a previously reported trend of increasing vulnerability with increasing size (Nakamura & Turner 1997).…”

“…The limited impact of Oithona on ciliates was unexpected, as it has been shown to be an effective cili-ate predator and to positively select for ciliates over similar-sized diatoms or dinoflagellates (Atkinson 1996, Nakamura & Turner 1997, Lonsdale et al 2000. Oithona is also known to reproduce in the Antarctic fall, implying a need to feed during the time of our study (Fransz & Gonzalez 1995).…”

Feeding by the cyclopoid copepod Oithona similis on the microplankton assemblage in the Oyashio region during spring

“…, Atkinson 1995, 1996, Castellani et al 2005a, with the exception of the extremely high value of ϳ75 mL copepod Ϫ1 d Ϫ1 at 0°C in Lonsdale et al (2000). However, it should be noted that our high clearance rates might be underestimates to some extent due to bottle effects (i.e.…”

“…Higher clearance rates on ciliates than on dinoflagellates or diatoms have been reported for O. similis (Nakamura & Turner 1997;Castellani et al 2005a) and other Oithona spp. (Lonsdale et al 2000;Atienza et al 2006), though the opposite trend has also been observed (Atkinson 1995(Atkinson , 1996.…”

“…Recent experimental studies employing natural prey assemblages have revealed that oithonids feed selectively on microzooplanktonic protists, such as ciliates and heterotrophic dinoflagellates (e.g. Nakamura & Turner 1997;Lonsdale et al 2000;Castellani et al 2005a; Atienza et al 2006). Considering their high abundance, oithonid copepods may serve as an important conduit to transfer microbial production to higher trophic levels in marine pelagic food webs.…”