Trophic interactions among sympatric zooplanktivorous fish species in volume change conditions in a large, shallow, tropical lake

Abstract

Significant reductions in the water volume of shallow lakes impose a restriction on species segregation promoting more interactions in the trophic relationships. The diets of three closely related zooplanktivorous silversides belonging to the Atherinopsidae species flock of lake Chapala, Mexico, were analyzed at two sites (Chirostoma jordani, C. labarcae, and C. consocium). Diets were described in critical shallow ( La reducción significativa en el volumen de agua de los lagos someros impone una restricción en la segregación de las especies y promueve una mayor interacción en las relaciones tróficas. Se analizó la dieta de tres especies cercanamente emparentadas de zooplanctívoros pertenecientes al flock de Aterinópsidos del lago de Chapala en dos sitios (Chirostoma jordani, C. labarcae y C. consocium). Las dieta fue descrita en una condición somera crítica (Agosto 2000) y en una condición de recuperación del lago (Agosto 2005). En la dieta se incluyen principalmente cladóceros (Bosmina, Ceriodaphnia y Daphnia) y copépodos (Cyclops). Se detectó una diferencia significativa en la dieta cuando se comparan los años (análisis MRPP, A = 0.22, p < 0.0001) y los sitios en los diferentes años (análisis MRPP, A = 0.17, p = 0.004). De acuerdo a los valores promedio de amplitud de nicho, las especies fueron clasificadas como especialistas y consumidores intermediarios. En condiciones someras, el pequeño intervalo de la amplitud de nicho (1.72 a 3.64) y los altos valores del traslape de nicho (D = 0.64, L = 8.62) indicaron un alto potencial para una interacción explotativa inter-específica. Cuando el lago se recupera en su volumen, un incremento en el intervalo de amplitud de nicho (1.04 a 4.96) y los bajos valores del traslape de nicho (D = 0.53, L = 2.32) indicaron una reducción en la interacción de las especies. La prueba U de Mann-Whitney refuerza este patrón al mostrar una diferencia significativa entre los años para el traslape de nicho (p = 0.006). El incremento en la interacción de las especies durante condiciones de volumen bajo, sugiere una segregación alternativa con variaciones en la historia de vida y en otras dimensiones del nicho como en el caso de la distribución espacial y temporal.

Stable isotope evidence for trophic overlap of sympatric Mexican Lake Chapala silversides (Teleostei: Atherinopsidae: Chirostoma spp.)

“…While they rely on zooplankton and fish as their main source of energy, our stable isotope data suggests that they may be also consuming food items with enriched δ 13 C values, relative to δ 13 C values for zooplankton as a group. Moncayo-Estrada et al (2011b) found zooplankton in genera Bosmina, Diaphanosoma, Daphnia, Ceriodaphnia, Diaptomus and Cyclops to be the main food items for C. labarcae, C. consocium and C. jordani. Given the known diet for species of Chirostoma, we expected these fish to have similar δ…”

“…Chirostoma species in Lake Chapala exhibit diverse jaw morphologies and body shapes that suggest different feeding habits among the eight species present in the lake. Evidence from gut content analyses has uncovered differences among species (Moncayo-Estrada et al, 2010, 2011b. In some cases, such differences have been attributed to changing Lake Chapala water levels (Moncayo-Estrada et al, 2011a), but other, fine scale studies have suggested preference of a species for a given zooplanktonic group (i.e., diet dominance of cladocerans vs. calanoid or cyclopoid copepods) (MoncayoEstrada et al, 2007).…”

“…1). Species of Chirostoma have been the focus of numerous investigations, including several studies related to diet (Moncayo-Estrada et al, 2007;Moncayo-Estrada et al, 2010;Moncayo-Estrada et al, 2011b), exploitation and fisheries (Berlanga-Robles et al, 2002), and phylogenetic relationships (Barbour, 1973b;Bloom et al, 2009Bloom et al, , 2012Bloom et al, , 2013. Based on morphometry and diet studies Lake Chapala "pescados blancos" such as C. sphyraena and C. promelas are considered primarily piscivorous, while "charales" such as C. consocium, C. jordani and C. labarcae are thought to be primarily zooplanktivores (Barbour, 1973a;Miller et al, 2005).…”

“…However, there are known differences among sympatric species in the relative contribution of zooplankton (e.g., calanoid and cyclopoid copepods, cladocerans), insects or fish to their diets (Wurtsbaugh & Li, 1985;Peck et al, 2003;MoncayoEstrada et al, 2010). For example, Moncayo-Estrada et al (2011b) reported significant diet niche overlap among three sympatric species of Chirostoma in Lake Chapala when the lake suffered water volume reductions, but niche separation when volumes were reestablished. Further, fish morphometry (i.e., head length, oral gape, and gill raker structure) has been related to differences in prey classes (Moncayo-Estrada et al, 2010).…”

Spatial patterns of zooplanktivore Chirostoma species (Atherinopsidae) during water-level fluctuation in the shallow tropical Lake Chapala, Mexico: seasonal and interannual analysis

“…In addition, this lake has the most important adaptive radiation of atherinopsids in fresh water: The Chirostoma flock consisting of eight species (Barbour, 1973;Barbour & Chernoff, 1984). We selected three species for the analysis -Chirostoma jordani, C. consocium, and C. labarcae -because they are the dominant species within the flock, they belong to the same guild (zooplanktivores), and they are the objective species of the local "charales" fishery (Moncayo-Estrada & Buelna-Osben, 2001;Moncayo-Estrada et al, 2011). Thus, these were expected to have strong population interactions related to the water fluctuations.…”