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Flora |
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Phytoplankton/Diatoms |
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A
thin scum of diatoms and blue-green algae was apparent on the northern
bank of the estuary in December 1981 (Ref. 1).
A small diatom bloom was noticed in the estuary opposite the
sewage outfall in 1979.
The high nutrient levels introduced by the sewage works, favour
eutrophication (the process by which a body of water is greatly
enriched by the natural or artificial addition of nutrients.
This may result in both beneficial and adverse –smothering by
dominant plant types – effects) (Ref. 1). |
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Algae |
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Within
the estuary Enteromorpha and Cladophora were recorded
and fragments of Ulva were obtained in D-net drags.
Filamentous algae were not abundant or predominant in this
estuary in 1981. |
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Aquatic
Vegetation |
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No
aquatic angiosperms were found in the estuary in 1981 (Ref. 1). |
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Semi-aquatic
Vegetation |
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During 1981, four groups of
semi-aquatic vegetation were represented in the Eerste River Estuary (Ref.
1),
namely:
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Intertidal
Fringe Vegetation comprising “gansgras” (Cotula
coronopifolia) and Scipus maritimus.
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Phragmites
australis Reeds,
comprising Phragmites australis and Scirpus
littoralis.
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Scirpus
maritimus Sedgeland.
Dune
Marsh Area,
comprising Paspalum vaginatum, bulrush (Typha capensis)
and numerous European weeds. |
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Terrestrial
vegetation |
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Three
types of vegetation were identified in 1981 (Ref. 1).: |
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Fore
Dunes, with “steekriet” (Eragrostis cyperoides),
“klappiesbrak” (Tetragonia decumbens), Heteroptilis
suffruticosa, Chrysanthemoides monilifera, sea weed (Agropyron
distichum), sea pumpkin (Arctotheca populifolia), Senecio
elegans and other dune plants. |
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Rhus
laevigata/Senecio
halimifolius Moist Shrubland,
with “Rooikrans” (Acacia cyclops), tabakbos (Senecio
halimifolius), “duine taaibos” (Rhus laevigata) and
saltbush (Atriplex vestita). |
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Acacia
Dominated
Dune Shrubland,
with Pelargonium capitum, “duine taaibos” (Rhus
laevigata), “blombos” (Metalasia muricata),
“pypgras” (Ehrharta villosa), “melkhout” (Sideroxylon
inerme) and the aliens ”Rooikrans” (Acacia cyclops) and
Port Jackson (A. saligna). |
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Fauna |
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Zooplankton |
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Zooplankton
samples taken on 1 December 1981 revealed that zooplankton were very
sparse and mainly dominated by Harpacticoid copepods (3 spp.),
Ostracoda and larval fish (Liza richardsoni) (Ref. 1). |
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Aquatic
Invertebrates |
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There
were no invertebrates on the hard substrata in the estuary in 1981 (Ref. 1). On
the soft substrata, the ocean crab (Hymenosoma orbiculare), the shrimp
(Palaemon pacificus), the sand prawn (Callianassa kraussi) and
interstitial meiofauna, such as nematodes, Harpacticoid copepods,
flatworms, Polychaeta, Oligochaeta, as well as eight Mollusc species
were reported. |
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Insects |
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In
1981, insects
collected included chironoid midges and larvae, dragonflies, kelp
flies, staphylinid beetles, other beetles, house flies, water boatmen,
ceratopogonid larvae and dead may-fly nymphs. (Ref. 1). |
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Fish |
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In
1981, fish
species recorded were sand gobies (Psammpgobius knysnaensis),
sole (Heteromycteris capensis), juvenile and post-larval stages
of Liza richardsoni, and “leervis” (Lichia amia). (Ref. 1). |
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Amphibians
and Reptiles |
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12
frog species and 11 snake spp. 8 lizard spp. and 4 tortoise spp. were
recorded in 1981 (Ref. 1). |
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Birds |
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33
bird species were recorded in 1981, with the sandwich tern being the
most abundant. |
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Mammals |
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Three
bat species, one shrew, one baboon, a southern seal elephant, grysbok,
Cape greater gerbil, Verreaux’s Rat, black and white Dormouse, Cape
dune Mole rat, Cape clawless otter, Cape wild cat, serval and leopard
were recorded by Stuart et al in 1980 (Ref. 5). |
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