In many coastal areas substrate is the limiting resource for benthic
organisms. Some sessile species can be used as secondary substrate, reducing
competition and increasing coexistence. In southern Chile, annual
populations of Macrocystis pyrifera recruit and grow on the
shells of Crepipatella fecunda. This study describes
ecological interactions between the kelp and the slipper limpet over an
annual cycle. The degree of kelp overgrowth was established by collecting
sporophytes and through in situ submarine photography over
a 10 month period (starting when kelp recruits became visible and ending
when sporophytes were no longer present). Changes in the biochemical
composition of the limpet tissue were also recorded by chemical analyses, to
evaluate the potential effects (positive/neutral/negative) of kelp on
C. fecunda nutritional condition. The results indicate
that both species coexist, although kelp overgrowth may cause a decrease in
carbohydrates in C. fecunda tissues, restricted to the
period when the kelp forest reaches its maximum biomass. Individually, the
short duration of the maximum overgrowth period and the size reached by
C. fecunda females (up to 65 mm shell length) may enable
rapid limpet recovery, avoiding competitive exclusion. On a population
level, the M. pyrifera annual cycle generates the needed
‘break’ for C. fecunda populations, reducing the effects of
kelp overgrowth. Thus, in the view of the neutral effect of kelp overgrowth,
together with the positive effect of C. fecunda on
M. pyrifera recruitment described somewhere else, this
ecological interaction can be categorized as commensalism.
Variability of Seawater Chemistry in a Kelp Forest Environment Is Linked to in situ Transgenerational Effects in the Purple Sea Urchin, Strongylocentrotus purpuratus
