South African Marine Ecosystems
Three investigations. Place every name CAPS asks for on a blank map, work out what makes a species endemic, and plot seventy years of African penguin numbers — a collapse that happened in your own bay.
Investigations column, block 53, in full: "Investigate endemic species along the coast" and "Investigate endangered species along the coast."
Those are Investigations 2 and 3 below. Investigation 1 is one this sheet adds, because the block's own core concept is "the names and placement of the ocean basins, coastal regions and biogeographic zones of South Africa" — and placing them on a map is the form that outcome takes in an exam. It is not a CAPS-listed investigation; it is here because the assessed skill needs rehearsing.
What you need
- 🟢 kitchen A pencil, a ruler and an eraser — the map work is pencil work, because you will want to correct it
- 🟢 kitchen Graph paper, or the ruled grid printed in Investigation 3
- 🟢 kitchen A calculator
- 🟡 optional Internet access, for the research half of Investigations 2 and 3
- 🌊 optional A low-tide window at a rocky shore, for the Investigation 2 extension
Both CAPS investigations are research tasks, which normally means "go and look it up". Every one of them on this sheet ships with a supplied data panel — described species cards and a real population data set — so you can complete every question, and earn every mark, without going online at all. If you do have access, use it for the extension work rather than the core task.
Aim
To identify and label the two ocean basins, three coastal regions, five biogeographic zones and four boundary landmarks of the South African coastline on an unlabelled map.
Method
- Close the topic page first. This is a recall task — using the labelled map while you do it teaches you nothing and takes about four minutes.
- Study the blank map below. Twelve numbered discs mark twelve features.
- Write the name of each numbered feature into the table that follows. Use the exact names CAPS uses.
- Then complete the second table, which asks for the three coastal regions rather than the zones.
- Only then open the topic page and mark yourself. Circle every one you got wrong — those are the ones to re-learn.
Discs 1–2 sit in open water. Discs 3, 9, 10, 11 and 12 sit on the coast. Discs 4–8 sit on the five coloured ribbons.
Results
| # | What kind of feature? | Name |
|---|---|---|
| 1 | Ocean basin | |
| 2 | Ocean basin | |
| 3 | Basin boundary | |
| 4 | Biogeographic zone | |
| 5 | Biogeographic zone | |
| 6 | Biogeographic zone | |
| 7 | Biogeographic zone | |
| 8 | Biogeographic zone | |
| 9 | Zone boundary landmark | |
| 10 | Zone boundary landmark | |
| 11 | Zone boundary landmark | |
| 12 | Zone boundary landmark |
| Coastal region | Temperature range | Its biogeographic zone(s) | Which basin? |
|---|---|---|---|
Analysis
- Complete Table 1.1. One mark per correctly named feature. 12
- Complete Table 1.2 — three regions, each with its temperature range, its zone or zones, and its basin. 9
- Only one of the twelve discs marks a boundary between basins rather than between zones. Give its number and its name, and explain in one sentence what the difference is. 3
- A learner writes: "Cape Point separates the Atlantic and Indian Oceans." Correct the statement, and explain what they have confused. 3
- The Warm Temperate region contains exactly one biogeographic zone. Name it, and explain why its name is easy to confuse with something else on this map. 2
- CAPS describes the eastern edge of the Warm Temperate region as "just north of East London" rather than giving a fixed point. Give one reason from the topic why that boundary cannot be drawn as a fixed line. 2
Aim
To investigate the endemic species of the South African coast, establish which coastal region holds most of them, and explain why being endemic changes a species' risk of extinction.
Method
- Read the four species cards in the supplied-data panel below. CAPS names these four by name for this block, so they are the four to know.
- Complete the results table from the cards.
- Answer the analysis questions.
- Choose one of the four and write the short research report in Q12. If you have internet access, extend it with current information; if not, the cards contain everything the mark scheme asks for.
Supplied data — the four species CAPS names
These are described cards rather than photographs — the same approach used in Topics 14 and 15. Everything you need to classify them and answer the questions is here.
Red Stumpnose
A deep red seabream with a steep forehead that develops a distinct bony hump in older adults. Endemic to South African waters and effectively confined to the south coast reefs. Slow-growing and long-lived, and it changes sex as it ages — the older, larger individuals are male. That is exactly the group fishing removes first, which is why the species has been heavily overexploited and is treated as a no-take species on the SASSI list.
Knysna Seahorse
Found naturally in only three South African estuaries — Knysna, Swartvlei and Keurbooms — and nowhere else on Earth. It lives among eelgrass (Zostera capensis), grips the blades with its prehensile tail and feeds on tiny crustaceans. Widely described as the most threatened seahorse in the world. Its whole global range would fit inside a single day's drive.
Leopard Catshark
A small, bottom-dwelling shark endemic to the southern African coast, patterned with dark rosettes like a leopard. Nocturnal: it rests in caves and gullies by day and hunts invertebrates and small fish at night. It lays tough egg cases — the "mermaid's purses" you find washed up — anchored to seaweed by curly tendrils.
Basket Star
Not a fish at all. Five arms branch, and branch again, and again, into a dense basket of hundreds of tips. By day it curls into a tight ball on a sea fan or reef; at night it unfurls the basket into the current and filter feeds, combing out plankton. A living demonstration that "star" animals are echinoderms, not fish.
Results
| Common name | Scientific name | Animal group | Region / BGZ where it is found |
|---|---|---|---|
Analysis
- Complete Table 2.1 — four species, four columns. Half a mark per cell, rounded to whole marks per row. 8
- Define endemic, then explain why an endemic species is at greater risk of extinction than a species with the same population size spread across three oceans. 4
- The Knysna Seahorse lives in only three estuaries. Explain why a single serious pollution event in one estuary is a national extinction risk rather than a local problem. 3
- Which coastal region does CAPS say has "numerous endemic species"? Then suggest two features of that region, from the topic page, that could help produce endemic species. 5
- Two of the four species on the cards are not bony fish. Name them, and give the animal group each one belongs to. 4
- Research report. Choose one of the four. Write 150–200 words covering: distribution, habitat, one adaptation and how it helps, and one threat. Marks: distribution (2), habitat (2), adaptation described and explained (3), threat (2), written in your own words at the right length (1). 10
Extension — do it on a real shore
Algoa Bay is twenty minutes away and sits at the eastern edge of the Warm Temperate region, so the endemics above are local animals, not textbook ones. At low tide at Cape Recife or Schoenmakerskop, run a 10 m transect down the shore from the high-water mark, record every species you can identify at 1 m intervals, then check afterwards which of them are southern African endemics. Empty leopard catshark egg cases are common in the strandline and are the easiest endemic to find.
Aim
To investigate endangered species of the South African coast, and to use real population data to describe and quantify the decline of the African penguin.
Method
- Read the supplied data panel.
- Plot the national breeding-pair figures as a line graph, following the seven graph rules from Topic 5.
- Do the calculations in Q14 and Q15 from your own graph and table.
- Complete the threat table and answer the written questions.
Supplied data — African penguin numbers, and three more endangered species
About these numbers. They are rounded from published census counts and are here so you can practise the graphing and the arithmetic. They show the real shape of the decline. If you ever write this up as a genuine research report, cite the current figures from DFFE or SANCCOB rather than these.
| Year | 1956 | 1979 | 1993 | 2004 | 2011 | 2019 | 2023 |
|---|---|---|---|---|---|---|---|
| Breeding pairs | 141 000 | 70 000 | 57 000 | 36 000 | 21 000 | 13 200 | 9 900 |
And in Algoa Bay specifically. St Croix Island held the largest African penguin colony in the world, with roughly 8 500 breeding pairs in 2015. Within about five years it had fallen to a few hundred. Bird Island, also in Algoa Bay, then became the largest colony — not because Bird Island grew, but because everywhere else shrank faster.
Three more endangered South African marine species:
Perlemoen (abalone)
A large sea snail that grazes drifting kelp. Slow-growing and very valuable, which has driven decades of organised illegal harvesting far beyond what the population can replace. Legal fishing is tightly restricted; the poaching is not.
Knysna Seahorse
Endemic and endangered at once. Threatened by anything that damages an estuary: silt, pollution, bait collection, boat moorings dragging through the eelgrass it lives in.
Red Stumpnose
Long-lived, slow to mature, and sex-changing, so fishing removes the breeding males first. Populations have fallen to a small fraction of their original size and it is a no-take species.
Results — plot your graph here
| Species | Main threat | Does it act on adults, chicks/young, or the food supply? |
|---|---|---|
| African penguin | ||
| Perlemoen | ||
| Knysna Seahorse | ||
| Red Stumpnose |
Analysis
- Plot Data set 3.1 as a line graph. Marks: correct axes chosen and labelled (2), units given (1), suitable scale using more than half the grid (2), title (1), points plotted accurately (3), points joined appropriately (1). 10
- Calculate the percentage decline in breeding pairs from 1956 to 2023. Show your working, and give your answer to one decimal place. 4
- (a) Work out the average loss in breeding pairs per year for the periods 1956–1979 and 2019–2023. (b) A classmate concludes that 1956–1979 was the worst period for the species because far more birds were lost then. Give one reason to disagree. 5
- The African penguin is both endemic to southern Africa and endangered. Explain why that combination is more serious than being either one on its own. 4
- Describe what happened at St Croix Island, and explain why "Bird Island is now the largest colony in the world" is not good news. 5
- Complete Table 3.1 for all four species. 8
- A penguin eats sardines and anchovies. Using what you know about the Benguela and the currents, suggest how a shift in where those fish are found could reduce penguin numbers even if nobody caught a single penguin. 4
- Both CAPS investigations for this block are research tasks. Two sources disagree about current penguin numbers: a government fisheries department report from this year, and a travel blog post with no date. Using the source-credibility test from Topic 5, say which you would use and give two reasons. 4
Write-up
Memo — worked answers and mark allocation (does not print)
Total: 109 marks — Investigation 1: 31 · Investigation 2: 34 · Investigation 3: 44.
Investigation 1 — Place the Names
- Q1 (12): 1 Atlantic Ocean Basin · 2 Indian Ocean Basin · 3 Cape Agulhas · 4 Namaqua BGZ · 5 South Western Cape BGZ · 6 Agulhas BGZ · 7 Natal BGZ · 8 Delagoa BGZ · 9 Cape Columbine · 10 Cape Point · 11 East London · 12 St Lucia.
- Q2 (9): Cool Temperate (CAPS: Cold Temperate) · 9–15 °C · Namaqua + South Western Cape · Atlantic. Warm Temperate · 16–20 °C · Agulhas · Indian. Subtropical · 18–27 °C · Natal + Delagoa · Indian. (3 marks per row.)
- Q3 (3): Disc 3, Cape Agulhas (2). It divides the two ocean basins; all the other landmarks divide biogeographic zones within a region or between regions (1).
- Q4 (3): It should read Cape Agulhas separates the Atlantic and Indian Ocean basins (1). They have confused the basin boundary with a zone boundary — Cape Point is the boundary between the South Western Cape BGZ and the Agulhas BGZ (2). Accept also: Cape Point is not the southernmost tip of Africa; Cape Agulhas is.
- Q5 (2): The Agulhas BGZ (1). "Agulhas" is also the name of the current, of the Agulhas Bank, and of Cape Agulhas — four different things on one coastline (1).
- Q6 (2): Any one of: the region's edges fluctuate seasonally as water temperatures rise and fall; it regularly receives an influx of colder water from the west along the shallow shelf; species overlap with both neighbouring regions, so there is no sharp biological line. (2)
Investigation 2 — Endemic Species
- Q7 (8): Red Stumpnose · Chrysoblephus gibbiceps · bony fish (seabream) · Warm Temperate, Agulhas BGZ. Knysna Seahorse · Hippocampus capensis · bony fish (seahorse) · Warm Temperate, Agulhas BGZ (estuaries). Leopard Catshark · Poroderma pantherinum · cartilaginous fish (shark) · Cool and Warm Temperate. Basket Star · Astrocladus euryale · echinoderm · Warm Temperate reefs. (2 per row.)
- Q8 (4): Endemic = found naturally in one place and nowhere else on Earth (2). Risk: if that one place is damaged the whole species is affected at once, so there is no population elsewhere to recolonise from — a widespread species can lose one population and recover (2).
- Q9 (3): Three estuaries is the species' entire world range (1). One event removes roughly a third of the global population (1), and because the three are separate systems the survivors cannot easily recolonise the damaged one (1).
- Q10 (5): The Warm Temperate region (1). Any two, well explained (2 each): it is a transition zone between two very different regions, so conditions there occur nowhere else; its edges fluctuate seasonally, so species must tolerate a moving temperature range; the influx of cold water along the shallow shelf creates local conditions distinct from either neighbour. Accept other reasoned answers.
- Q11 (4): Leopard Catshark — a cartilaginous fish / shark (2). Basket Star — an echinoderm (2). Do not accept "starfish" as a group name.
- Q12 (10): Mark against the stated split. Full marks need the adaptation explained, not just named — e.g. the seahorse's prehensile tail grips eelgrass so it holds station in a tidal current instead of being swept out of the estuary.
Investigation 3 — Endangered Species
- Q13 (10): Year on the x-axis (independent variable), breeding pairs on the y-axis (dependent). Note the x-axis intervals are uneven — a good graph spaces the years to scale rather than evenly, and a learner who spaces them evenly should lose the scale mark.
- Q14 (4): (141 000 − 9 900) ÷ 141 000 × 100 (2) = 131 100 ÷ 141 000 × 100 (1) = 93.0 % (1).
- Q15 (5): (a) 1956–79: 71 000 ÷ 23 = ≈ 3 087 pairs/year (2). 2019–23: 3 300 ÷ 4 = 825 pairs/year (1). (b) Any one, well argued (2): the early loss was from a huge population, while the recent loss is from a tiny one — 825 pairs a year out of 13 200 is a far larger proportion (about 6 % a year) than 3 087 out of 141 000 (about 2 %); at the recent rate the species has only about a decade of birds left; and a small population is additionally vulnerable to a single bad event.
- Q16 (4): Endemic means there is no population anywhere else in the world to act as a reserve (2). So "endangered" here means endangered globally, not locally — if it goes from southern Africa it is gone entirely, and no other country can restock it (2).
- Q17 (5): St Croix held the world's largest colony, about 8 500 breeding pairs in 2015 (1), and collapsed to a few hundred within roughly five years (1). Bird Island inheriting the title is not good news because the title moved without Bird Island growing (2) — being "largest" now describes a much smaller colony than "largest" described a decade ago, so the ranking has improved while the species has got worse (1).
- Q18 (8): African penguin — competition with purse-seine fishing for sardine and anchovy, or prey shifting away from the colonies → food supply. Perlemoen — illegal harvesting → adults. Knysna Seahorse — estuary damage, pollution, loss of eelgrass → habitat, affecting adults and young. Red Stumpnose — line fishing removing the large old sex-changed males → adults. (2 per row.)
- Q19 (4): Penguins are central-place foragers: they must return to the same island to feed a chick (1). If the sardines and anchovies shift east or further offshore, the round trip becomes longer (1), so adults either return with less food or the chick waits longer between meals (1) — chicks starve, breeding success falls, and the colony shrinks without a single adult being killed (1).
- Q20 (4): The government fisheries report (1) — any two reasons (3): it is dated and current, whereas the blog is undated so you cannot tell what year it describes; it comes from the body that actually runs the census, so it is a primary source; a travel blog has no stated method and no accountability; the report can be checked and cited.
Marking note. Q12 and Q17 are extended-writing answers. Award marks for the points listed, not for length — a 150-word answer that hits every point beats a 400-word one that does not.