10.5061/DRYAD.RV15DV47V
Yakovis, Eugeniy
0000-0003-3489-3671
Saint Petersburg State University
Artemieva, Anna
Saint Petersburg State University
Data from: Effects of a trophic cascade on a multi-level facilitation cascade
Dryad
dataset
2021
Crabs
Shrimp
foundation species
facilitation cascade
top-down control
FOS: Biological sciences
Russian Foundation for Basic Research
https://ror.org/02mh1ke95
13-04-10178
Russian Foundation for Basic Research
https://ror.org/02mh1ke95
14-04-00972
Russian Foundation for Basic Research
https://ror.org/02mh1ke95
14-04-10124
Russian Foundation for Basic Research
https://ror.org/02mh1ke95
17-04-00651
Russian Foundation for Basic Research
https://ror.org/02mh1ke95
20-04-00835
2021-06-22T00:00:00Z
2021-06-22T00:00:00Z
en
29861 bytes
3
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
1. The role of cascades in natural communities has been extensively
studied, but interactions between trophic and facilitation cascades are
unexplored. In the White Sea (65° N) shallow subtidal bivalve primary
facilitators provide hard substrate for secondary facilitator barnacles,
that in turn provide substrate for conspecifics, ascidians, red algae, and
multiple associated organisms, composing a multi-level facilitation
cascade. Previous research revealed that predation by the whelk
(Boreotrophon clathratus) accounts for ~7% of adult barnacle mortality.
Low whelk abundance limits their effect, with barnacles living on
conspecifics several times more vulnerable to predation than those living
on primary substrate. 2. Trophic cascades can selectively shield
foundation species from consumers, and hence may affect the structure and
length of facilitation cascades. We tested the hypothesis that low
abundance of the whelks results from mesopredator predation on their
juveniles. Depending on the magnitude of the effect, this would mean that
a trophic cascade controls the abundance of barnacles on all substrates or
only barnacles living on conspecifics. We also suggested that barnacles on
primary substrates and conspecifics facilitate different dependent
assemblages. 3. We manipulated the presence of crab and shrimp
mesopredators in field caging experiments to assess their effect on whelk
recruitment. In a field survey we compared the assemblages of sessile
macrobenthic organisms associated with barnacles living on different
substrates. 4. Caging experiments evidenced that crab and shrimp
mesopredators reduce whelk recruitment by 4.6 times. Field data showed
that barnacles on primary substrate and on conspecifics promote different
dependent assemblages including secondary facilitator ascidians. 5.
Although mesopredators do not shield barnacles from elimination, their
absence would restrict them from living on conspecifics. Barnacles on
conspecifics are functially different from barnacles on primary substrate,
and can be concidered a separate level of the facilitation cascade.
Trophic cascades thus can generate community-wide effects on facilitation
cascades by affecting their structure and possibly length.
Field experiments. We tested mesopredator effects on Boreotrophon
clathratus (hereafter 'whelk') recruitment to barnacle clusters
in a series of year-long field experiments conducted at a 12 m deep
subtidal site in the Solovetsky Islands (65°01.180’N, 35°39.721’E, see
Yakovis & Artemieva, 2015). In July 2009-2012 and 2015 we
collected empty shells with live Balanus crenatus and similar shells with
empty barnacle tests (the latter are almost equally abundant in the
field). We defaunated these shells except of adult barnacles (4 or more
annual growth rings) and their empty tests and attached them in
alternating order to the bottom of 300×375×70 mm plastic cages covered
with 2.5 mm nylon mesh (2-3 shells with live barnacles and 2-3 shells with
empty tests per cage). Boreotrophon is a direct-developer with crawl-away
recruits, attaching egg masses to hard substrates, with a lifespan of
several years. The mesh is permeable for juvenile whelks with shell height
within 7 mm (Yakovis & Artemieva, 2015). Each year we deployed a
new set of cages (which were collected next year) randomly distributed
between 2-5 treatments: (i) full cages (predator exclusions) and (ii) open
cages (unmanipulated controls, no mesh, subject to normal predation) in
all years; (iii) partial cages to control for caging effects, similar to
full cages but with two side windows 175×50 mm each, in all years except
2012; (iv) cages with predatory spider crabs Hyas araneus (crab
enclosures) in 2015 only, and (v) cages with predatory shrimp
Spirontocaris phippsi (shrimp enclosures) in 2015 only. The set of cages
deployed in 2015 was also used to assess the effect of crustacean
predators on other mobile fauna associated with barnacles (Yakovis
& Artemieva, 2019). There were 2 cages/treatment/year in
2009-2010, 2010-2011, 2011-2012, and 2012-2013. In 2015-2016 there were 6
cages/treatment, except for predator exclusions, which were 8, and open
cages, which were 5. We exposed all the cages anchored to the bottom in a
haphazard pattern (≥0.5 m apart) for one year, collected them, counted,
weighed and individually measured (since 2011) crabs and shrimp with
carapace length ≥2.5 mm and whelks with shell height ≥0.5 mm found inside
(except for crustaceans in open cages, which were too mobile to be sampled
in absence of mesh). For details of the 2015-2016 predator enclosures
experiment see Yakovis & Artemieva (2019). In the field whelks,
crabs and shrimps concentrate in patches formed by barnacles and their
empty tests rather than on unstructured sediment. Thus, the abundance of
predators is more related to that of adult barnacles rather than bottom
area. To account for that, barnacle weight in each cage was estimated in
the end of the experiments from aperture length measurements using
allometric relationships (Yakovis & Artemieva, 2015). Empty
barnacle tests were also measured and their equivalent weight was
calculated using the same allometric relationships. The sum of calculated
weights of live and dead barnacles is hereafter called equivalent barnacle
weight, EBW, 151±6 g per cage (n=53). Field survey. To compare associated
assemblages of sessile organisms between barnacles attached to primary and
secondary hard substrates (which are differently affected by predators) we
used eight samples obtained by SCUBA divers at the experimental site
(65°01.180’N, 35°39.721’E) in July 2012-2014. Each sample contained all
the hard substrates visible on the sediment surface collected from a 0.25
m2 square frame haphazardly placed on the bottom (10-26 such primary
substrates per frame). We counted and identified all the sessile
macrobenthic organisms larger than 0.3 mm by substrate type; the
individuals attached to first- and second-layer barnacles were recorded
separately. References. Yakovis E., & Artemieva, A. (2015). Bored
to death: community-wide effect of predation on a foundation species in a
low-disturbance arctic subtidal system. PLoS ONE 10:e0132973.
http://dx.doi.org/10.1371/journal.pone.0132973 Yakovis, E., &
Artemieva, A. (2019). Epibenthic predators control mobile macrofauna
associated with a foundation species in a subarctic subtidal community.
Ecology and Evolution, 9, 10499– 10512. https://doi.org/10.1002/ece3.5570
Tabs 'Experiments 2009-2012' and 'Experiments
2015-2016' contain raw data from the field experiments. The tab
'Field Survey' contains raw data from the field survey.