Tintinnoinea
Vertical distribution

Literature on vertical distribution of Atlantic tintinnids is less extensive than on geographic distribution, largely restricted to short remarks on records of various taxa in isolated vertical casts. Balech (1972) classified subsurface species vaguely into three groups (species with dubious depth-preferences were included in a fourth group, omitted herein) according to their increasing degree of preference for deep ("shaded") waters, as follows:

Shallow: Ascampbelliella, Codonella acuta, Codonella aspera, Xystonella treforti, and others.
Intermediate: probably all species of Salpingella, Undella hyalina, Codonaria cistellula, and others.
Deep: probably all species of Amplectella, Brandtiella palliata, Ormosella, Parundella, Undellopsis, most species of Xystonellopsis, and others.

Quantitative vertical profiles for the extrapolar South Atlantic are restricted to subsurface (5-15 m) oceanic waters ranging from subtropical to Antarctic latitudes (Alder, unpublished). Although of limited value for comprehensive analyses, these data confirm that Balech's "true shade species" ("Deep") are indeed totally absent from the upper 15 m.

All available information on the vertical distributional of tintinnid species in the Atlantic sector of the Southern Ocean was summarized by Boltovskoy and Alder (1992) and Alder (1995). Based on detailed quantitative profiles of discrete depth intervals between 0 and 1000 m, Alder (op. cit.) concluded that not all species are restricted to preferential depths. Species with restricted depth ranges, however, decrease in abundance with depth such that deeper-living species are scarcer than shallower ones. Depth preferences were classified into 3 groups:

0-50 m: Laackmanniella naviculaefera and Codonellopsis gaussi;
40-70 m: Cymatocylis convallaria and Cymatocylis drygalskii;
80-250 m: Cymatocylis vanhoffeni.

Although the abundance of some species can undergo very significant seasonal fluctuations, often resulting in shifting winter-summer dominance patterns (e.g. off Hope Bay; Alder, 1995), vertical distribution does not seem to be affected by such changes.

Several studies on tintinnids in sediment trap samples have appeared recently (e.g., Bathmann et al., 1987, 1990; Dale, 1989; Nöthig and Von Bodungen, 1989; Ling, 1992; Boltovskoy et al., 1993a, 1996). Boltovskoy et al. (1993a, 1996) and Uliana (1997) analyzed materials from various depths in two nearby, highly productive sites in the eastern tropical Atlantic, reporting flux rates in excess of 200,000 ind. mö-2 dayö-1 (geographic locations). Based on indirect comparisons with usual tintinnid concentrations in productive surface and subsurface tropical waters (around 100,000 ind. mö-3), over 99% of the loricae produced at these sites appear to be lost to sedimentation before reaching 800-2000 m. On the other hand, proportions of deteriorated loricae increase only slightly with depth below ca. 800 m, suggesting that destructive processes are of minor importance at mesopelagic depths. As opposed to overall abundance, species relationships seem to change little with depth (Ling, 1992), indicating that susceptibility to destruction by grazing and bacterial activity is similar for the different species.