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.