viii latin american congress of ecology
TRANSCRIPT
DIETARY PATTERNS OF SOME CHITONS OF THE
INTERTIDAL ROCKY SHORES FROM THE NORTH OF ISLA
DE MARGARITA, VENEZUELA.
Carrasquel María, Velásquez Marcel y Lira Carlos
Universidad de Oriente, Núcleo Nueva Esparta, Escuela de Ciencias Aplicadas del Mar (ECAM), Isla de Margarita, Venezuela.
METHODOLOGY
The collection of the samples was made monthly from
october 2010 to february 2011 in the intertidal rocky shores of
five beaches at the north of Isla de Margarita, Venezuela.
Figura 1. Sampling locations at the north of Isla de Margarita,
Venezuela: 1. Manzanillo Beach; 2. Zaragoza Beach; 3. Taguantar; 4. El
Tunal y 5. La Pared Beach.
INTRODUCTION
Several investigations indicate that the chitons, as many other
herbivorous species from the intertidal systems, tend to ingest
regularly animal food like: hydroids, bryozoos, barnacles,
molluscs, marine sponges, amphipods and nematodes, having
significative effects on the distribution and abundance of these
populations (Brandani et al., 1974; Langer, 1983; Latyshev et al.,
2003; Aguilera, 2005; Camus et al., 2008). Due to this, the roll
and impact of the chitons on the trofic web of the intertidal
rocky shore communities is more diverse and complex than
what’s been thought; they are one of the biggest and
ecologically important groups of herbivorous, but also less
known in trofic terms. Due to this, the main objective of this
study is to determinate the diet composition of four species of
chitons: Acanthopleura granulata, Chiton marmoratus,
Ceratozona squalida y Calistochiton portobelensis, from five
intertidal rocky shore communities at the north of Isla de
Margarita, Venezuela.
Spicules of
Perinoto
Nerita sp
Mitrella cellata
Amphípod
Scales of
Perinoto
Rocks
Fragments of
Barnacles
Preservation of the digestive tract in formalin 10%
Dissection of stomach and intestine
RESULTS
Figure 2. Percentage of animal, vegetable and rocky items of four
species of chitons from the intertidal rocky shore at the north of Isla de
Margarita, Venezuela.
Figure 3. Percentage of ocurrence of each item present in the diet of four species of chiton
from the intertidal rocky shores at the north of Isla de Margarita, Venezuela.
Discussion and Conclucions
Several studies have reported the presence of ciprys larvae, barnacles in post-metamorphic
stages and many other invertebrates: clams, gastropods, amphipods and nematodes in the diet
of intertidal chitons (Langer, 1983; Latyshev et al., 2003; Aguilera, 2005; Camus et al., 2008).
The frecuent intake of invertebrates by the chitons can be considered as a mechanism to
create and mantain the biodiversity of populations of the intertidal rocky shores (Lubchenko,
1978), and it may help to reduce the competition by exclusion when the predator and the prey
share the same vegetable source of food in some seasons of the year (Camus et al., 2008).
The presence of plates, scales and spicules of poliplacoforos in the digestive tract do not
indicate interspecific predation, but aggressive behaviour from some chitons to defend or
compete for the resting areas, such is the case of many chitons from the genera Acanthopleura
(Chelazzi et al., 1983)