Malcolm Giffen was one of the pioneers in this field of study and described many marine coastal diatom taxa in South Africa. Of the 10 marine littoral diatom specimens Giffen collected from the Kidd's Beach area, 8 were used to describe 27 new diatom species. A CCA bi-plot was used to represent the influence of the physico-chemical variables on the diatom community.
The resampling of the 8 sites in question yielded only 6 of the 27 taxa described as new by Giffen.
Introduction and literature review
The ocean
- Global climate
- Zones in the ocean
- CO 2 storage
To better explain the concepts below, a brief description of the different zones in the sea is first given. The abyssal zone is the second deepest zone of the sea floor, extending over depths of m and considered to be the sea floor of the corresponding abyssal pelagic zone (Pinet, 2009). The process of the biological pump is complex and the atmospheric CO2 undergoes some changes before it ends up in the deep ocean (Boppet al., 2017).
However, increased DIC also lowers ocean pH contributing to ocean acidification, leading to stronger stratification (this process is when a body of water, for example the ocean, forms different layers due to different densities of layers) that is also intensified with increasing temperature by residual CO2 not absorbed by the ocean (Basu & Mackey, 2018).
Primary production
The second pump, with the largest contribution to the ocean carbon pump, is the biological pump (Marinov & Sarmiento, 2004). This pump relies on the transport of DIC from the ocean surface to the deep ocean and ocean sediment via the highly integrated marine food web (Bopp et al., 2017). The high amount of phytoplankton in the ocean west of continents is mainly due to upwelling, which brings cold nutrient water to the surface (Helbling & Villafañe, 2009; Basu & Mackey, 2018).
In the polar regions of the Northern Hemisphere, high abundances of phytoplankton occur together with periodic booms associated with retreating ice cubes.
Marine algae and diatoms
Another characteristic of Haptophyta is the presence of a haptoneme, which is a flagella-like organelle but with a distinct ultrastructure (Malcataet al., 2018). Dinoflagellata is a supergroup of the stem Miozoa (Malcata et al., 2018) and is mostly marine, with only 10% of the superclass living in fresh water (Krienitz, 2009). The cingulum groove contains the cingulum flagellum, which is responsible for cell rotation.
The sulcus groove is present longitudinally on the ventral side of the cell and contains the sulcus flagellum which is responsible for the navigation and forward movement of the cell (Malcataet al., 2018; Krienitz, 2009).
Diatoms
- Habitats
Although Chlorophyta is dominated by unicellular freshwater species, the marine species in this group are macroalgae (Malcataet al., 2018). In contrast to Chlorophyta, Haptophyta are dominated by marine species, with only a few freshwater species (Malcataet al., 2018; Krienitz, 2009), with coccolithophores being one of the most abundant groups of marine plankton, especially in the oceanic zone. In terms of habitat, diatoms are a very diverse group of organisms that can be planktonic, cryophyte (algae that occur in snow and ice), or benthic - which in turn can be divided into more subgroups depending on the substrate in which diatoms join (Simon et al., 2009; Taylor & Cocquyt, 2016; Malcata et al., 2018).
Benthic diatoms can be epizoic (algae that live non-parasitically on the surface of another animal), epiphytic (algae that live on another plant), epilithic (algae that grow on the surface of stones and rocks), epipelic (algae that grow on the surface of sediment and mud), epixylic (algae that grow on wood) and epipsamic (algae that attach to sand grains) (Simon et al., 2009; Taylor & Cocquyt, 2016; Malcataet al., 2018).
Diatoms in the littoral zone
- Diatoms as primary producers in the littoral zone
- Sediment stabilisation by diatoms
According to Christiansen et al. 2017) diatoms and cyanobacteria are the most abundant taxonomic groups in the microphytobenthos. However, Semcheski (2014) says that other algal groups (such as cyanobacteria and chlorophytes) have been overlooked as major contributors to the primary production in the benthos of the coastal area. Furthermore, water-extractable slime is soluble in water and decreases in the sediment as submergence occurs and photosynthesis decreases.
Second, EDTA-extractable slime is not or only slightly subject to degradation by diatoms in the dark period.
International research regarding littoral zone diatoms
Garcia (2016) documented the morphology, taxonomy and distribution of five species (Campylosira cymbelliformis, Cymatosira belgica, Cymatosirella minutissima, Plagiogrammopsis minima and Plagiogrammopsis vanheurckii) of the class Cymatosiraceae from the coastal area of Santa Catarina and Rio Grande do Sul. This genus may be inaccessible under LM due to small cell size (Amspoker, 2016). Nevrova and Petrov (2019) studied diatom communities in four bays (Dvuyakornaya Bay, Cape Fiolent, Sevastopol Bay and Balaklava Bay) on the Crimean coast, observing a total of 543 taxa.
This may be due to the similarity of environmental conditions on both islands.
South African research on littoral zone diatoms
- M. H. Giffen
- Further contributions to research on marine littoral diatoms in South Africa
Giffen An account of littoral diatoms from Langebaan, Saldanha Bay, Cape Province, South Africa. Giffen A further description of the marine littoral diatoms of Saldanha Bay Lagoon, Cape Province, South Africa. Cholnoky (1962) noted a total of 177 taxa from three localities and the distribution of taxa among sampling sites.
In conclusion, Cholnoky (1965) suggested that if the conditions present during the time of this study (closed lagoon and high productivity) persisted, it would be inevitable that the lake would change to a more terrestrial system as a result of the accumulation of sand and water. organic matter, Cholnoky (1965) also predicted that the shallower parts of the lake would be affected (and silted up) first, with the northern end of the lake remaining a slowly silting swamp/lake area.
Diatom taxonomy
Aims and objectives
Materials and methods
Study area
Giffen’s material
Contributions to the Diatom Flora of South Africa, III Diatoms from the Marine Kut Region at Kidd's Beach Near East London, Cape Province, South Africa. A Nikon ECLIPSE 80i Light microscope equipped with a Nikon digital sight DS-U2 camera system was used to obtain the LM photomicrographs of 26 of the 27 diatom taxa involved. The subsamples of the original material were sonicated and cleaned again using the same method described below for more recent samples.
The stubs were then sputter-coated with carbon and gold-palladium and used to obtain electron micrographs of 23 of the 27 taxa in question, using a FEI Quanta 2000 F-SEM (10 KV, WD 10 mm).
Resampling from Giffen’s study sites
- Statistical analysis
This station was exposed after the river mouth (lagoon) opened after the tide and the water level dropped about 1.5 m. 197_G 30 January 1946 From pools at high tide mark along beach north-east of river mouth. From the pools at the high tide mark along the beach to the north-east of the mouth of the river.
CCA was used to illustrate the influence of the physicochemical variables on diatom community composition at Kidd's Beach in 2019.
Augmented and emended taxa descriptions of the 27 taxa described by Giffen from
Under SEM, the outer distal raphe tips are slightly expanded, pore-like, and terminate at the anterior face of the valve ( Fig. 5H ). The outer distal tips of the raphe are straight and simple and do not extend beyond the valve margin (Fig. 11G). Externally, the proximal ends of the raphe are straight, simple, and pore-like, terminating in a ridge on the valve margin ( Fig. 11J ).
The internal distal raphe ends are straight and simple and extend to the valve margin (Fig. 11I). Externally, the striae extend over the valve margin and consist of slit-like areolae (Fig. 12J). The inner proximal raphe ends are straight and simple and end in a slight silica thickening (Fig. 16O).
Under SEM, the external distal raphe ends are sickle-shaped and extend onto the mantle (Fig. 17H). The external proximal raphe ends are straight and simple and end in a small siliceous protrusion (Fig. 19F). Under SEM, the external distal raphe ends are gradually hooked, sickle-like, and extend over the mantle (Fig. 21I).
The outer proximal raphe ends are straight and simple and terminate in a small silica thickening (Fig. 21G). Under SEM, the external distal raphe ends are straight, sickle-like, and terminate on the valve face (Fig. 22N). Externally in the center of the valve next to the axial area, a buciniportula is present (Fig. 22O).
The outer proximal raphe are straight and leek-like and open into narrow spatulate grooves (Fig. 23I).
Temporal changes in the littoral diatom assemblage at Kidd’s Beach between the mid-20 th
This is due to the presence and relative dominance of Nitzschia frustulum in all samples (Table 3). Sample 197_G has a very weak correlation with the rest of the samples due to the very low abundance of Nitzschia frustulum. The remaining sample shows a very weak correlation with the rest of the samples (Figure VII).
Overall, the community structure of all eight sites in question changed noticeably between the time Giffen sampled and 2018, as illustrated by the weak correlation between the majority of the 2018 samples and those collected by Giffen. Three groups can be identified where correlations are observed between the samples collected in 2019 and those collected by Giffen, with a deviant sample (197_19). A relatively strong correlation can be observed between all the samples excluding sample 165_19, which shows a weak correlation with the rest of the samples in group 1.
The weak correlation observed between sample 165_19 and the rest of the samples in the group is due to the high abundance of Navicula perrrhombus (32.76%), which has a low abundance in the rest of the samples in this group ( Table 6). Although there is a stronger correlation between samples 509_G and 210_19, as these sites share four species (Achnanthes brevipes, Navicula perrrhombus, Nitzschia sp9 and Nitzschia sp4) (Table 6), the community structure of site 210 (sample 210_19) was sampled in 2019 shifted more towards the community structure of the corresponding samples collected by Giffen compared to the samples collected in 2018. The reason for the correlations between all samples in this group is related to the presence of sp14 (absent in sample 195_G) and Navicula sp11 (absent in sample 197_G) at most locations (Table 7).
Sample 197_19 is not within the group, although this sample shares several species with the other samples (Fig. VIII). In general, it can be observed that the community structure found in the samples collected in 2019 is relatively similar to the community structure of the samples collected by Giffen, despite the fact that the diatom community structure documented in 2018 was very different.
Conclusions
M., 1983. Diatoms of the Sundays and Big Fish Rivers in the Eastern Cape Province of South Africa. Contributions to the diatom flora of South Africa, III Diatoms of the marine littoral regions at Kidd's Beach near East London, Cape Province, South Africa.Nova Hedwigia. Littoral marine diatoms of the Kowie River Estuary, Port Alfred, Cape Province.
Description of littoral diatoms from Langebaan, Saldanha Bay, Cape Province, South Africa. Marina Botanica. Further description of the marine littoral diatoms in Saldanha Bay Lagoon, Cape Province, South Africa. Botanica Marina.
