Table T3. Species compositon and related environmental preferences of the seven diatom groups, Site 1077.
|
Diatom group
|
Species
composition (average %) |
Environmental
conditions
|
|---|---|---|
| Freshwater | 2.7 | Related to the Congo River discharge |
| Aulacoseira spp. | 64.0 | |
| Marine | 97.3 | |
| Nearshore | ||
| Low salinity | 18.8 | Related to the Congo River plume |
| Cyclotella litoralis | ||
| High nutrients | 64.0 | |
| Chaetoceros spp | 24.2 | Highly productive waters where river-induced upwelling is inferred |
| Thalassionema nitzschioides var. nitzschioides | 39.8 | Highly productive nearshore waters to the north of the river plume nearshore |
| Neritic | 11.0 | |
| Actinocyclus aff. curvatulus | ||
| Actinocyclus octonarius | ||
| Coscinodiscus radiatus | ||
| Rhizosolenia setigera/pungens | ||
| Skeletonema costatum | ||
| Thalassiosira angulata | ||
| Thalassiosira eccentrica | ||
| Littoral | 0.7 | Transported from the shelf |
| Actinoptychus senarius | ||
| Actinoptychus vulgaris | ||
| Offshore | ||
| Warm | 1.7 | Related to the warm, high saline waters of the SECC with low nutrient levels |
| Alveus marinus | ||
| Asteromphalus flabellatus | ||
| Azpeitia nodulifera | ||
| Nitzschia interruptestriata | ||
| Planktoniella sol | ||
| Pseudosolenia calcar-avis | ||
| Rhizosolenia bergonii | ||
| Thalassionema nitzschioides var. parva | ||
| Thalassionema nitzschioides var. inflatula | ||
| Thalassiosira ferelineata | ||
| Thalassiosira lineata | ||
| Thalassiosira simonsenii | ||
| Oceanic temperate | 3.2 | Related to cold, nutrient-rich waters of the BCC, probably reflecting northward movement of the ABF |
| Bacteriastrum elongongatum/furcatum | ||
| Fragilariopsis doliolus | ||
| Thalassiosira oestrupii var. oestrupii |
Notes: Data are based on observations of van Iperen et al. (1987), Pokras and Molfino (1986), and Romero et al., (1999a). SECC = South Equatorial Countercurrent, BCC = Benguela Coastal Current, ABF = Angola Benguela Front.