Question 19M.3.SL.TZ2.c
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ2.c |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Analyse | Question number | c | Adapted from | N/A |
A survey was made of the intertidal zone at Butter Lump Bay, Great Cumbrae, Scotland. The three species of barnacle found were Elminius modestus (EM), Chthamalus montagui (CM) and Semibalanus balanoides (SB). The kite diagram shows the vertical distribution of these three species from the low tide mark at 0 m to 2.25 m above low tide.
[Source: reprinted from Estuarine Coastal and Shelf Science, 152, M C Gallagher, et al., The invasive barnacle species,
Austrominius modestus: Its status and competition with indigenous barnacles on the Isle of Cumbrae, Scotland,
pages 134–141, 2014 with permission from Elsevier]
E. modestus is an invasive barnacle while the others are native species. Analyse the data to show how it supports this statement.
[2]
a. native species/C. montagui and S. balanoides have niches that don’t overlap much / are distinct
OR
range of E. modestus overlaps with both native species ✔
b. niches of native species «which don’t overlap much» shows competition between native species
OR
E.modestus invades habitats of C. montagui/S. balanoides resulting in competition with «both» native species ✔
c. EM has a wide niche/higher tolerance/covers entire «intertidal» range making it easier to invade the habitat ✔
Candidates had difficulty finding data to support E.modestus being aninvasive barnacle in part (c).
