Spatial and temporal variation in the diet of the sandy beach gastropod Olivella minuta

Abstract

Marine gastropods exert a strong influence on the structure of marine ecosystems through their foraging activities, yet little is known about how environmental differences in space and time may affect their feeding behavior. To enhance the knowledge about the trophic ecology of coastal benthic species, we investigated temporal and spatial variations in the diet of the sandy beach gastropod Olivella minuta. We collected individuals of O. minuta seasonally, over 1 year, at two sandy beaches with different morphodynamic characteristics (Araçá Bay, an ultra-dissipative tidal flat, and Barequeçaba Beach, a dissipative beach) and analyzed the stomach contents of specimens of O. minuta. We identified approximately 15,000 food items, which we grouped into 14 categories. Thirteen food categories were found at each area, but significant differences in diet were observed between sites and sampling periods. Individuals from Araçá consumed an overall larger quantity and diversity of food items, which consisted mainly of foraminiferans, polychaetes, and crustaceans.At Barequeçaba, diatoms were the most important item, followed by crustaceans and polychaetes. Temporal variation depended on sites: the number of food items in the stomachs of individuals of O. minuta and dietary composition was roughly constant over time at Araçá, whereas larger variations were observed at Barequeçaba. Although O. minuta has been previously characterized as a carnivore/scavenger, our results show that the diet of this species varies in space and time and comprises a large variety of food resources. The species thus plays a role in the cycling of both vegetal and animal organic matter. This generalist behavior may allow individuals to shift their diet according to habitat alterations and food availability, thereby enhancing the persistence and resilience of O. minuta in different environments or future climate change scenarios. K E Y W O R D S coastal ecosystems, frequency of occurrence, numeric importance, stomach content, trophic ecology S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Corte GN, Yokoyama LQ, Checon HH, Turra A. Spatial and temporal variation in the diet of the sandy beach gastropod Olivella minuta. Invertebr Biol.

Full stomachs at empty tides: tidal cycle affects feeding activity and diet of the sandy beach gastropod Olivella minuta

“…Our results, however, indicate that this species should be regarded as an omnivore; our data show that the diet ranges from autotrophic (microalgae and macroalgae) to heterotrophic prey, and this agrees with the results of a recent study by Corte et al (2019). We found macroalgae to be a dominant component of the diet and this contrasts with previous studies of the diet of O. minuta (Marcus & Marcus, 1959;Arruda et al, 2003;Corte et al, 2019). Our findings may reflect increases in drifting and beach-cast macroalgae due to seasonal or stochastic events (e.g.…”

“…storms) at Barequeçaba (H. Checon, personal observation). Although our results are likely to have been influenced by seasonal events, they nonetheless highlight the omnivorous diet and opportunistic feeding behaviour of O. minuta; this species is known to be able to shift its diet in response to temporal changes in the environment (Corte et al, 2019). Evidence from stable isotope analysis showing that O. minuta feeds on more than one trophic level (Angelini et al, 2018) also supports the view that this species is an omnivore.…”

“…When a food item is found, the snail wraps the item on the metapodium and fully or partially ingests it by burying itself in the sediment and protracting the proboscis (Arruda et al, 2003). Thus far, a few studies have evaluated the diet of this species, classifying it as a carnivore/scavenger or omnivore based on the presence of a range of food items, such as crustaceans, foraminiferans, scaphopods and microalgae, in the stomach (Marcus & Marcus, 1959: as Olivella verreauxi Ducros de Saint Germain, 1857; Arruda et al, 2003;Corte et al, 2019). These studies have provided important information on the feeding behaviour of O. minuta.…”

The science we need for the beaches we want: frontiers of the flourishing Brazilian ecological sandy beach research

“…Studies were also spatially restricted to supratidal and intertidal zones, with only a few studies sampling the subtidal or the whole across-shore gradient (e.g., Corte et al, 2019;Corte et al, 2020;Corte et al, 2022). Investigations mainly focused on macrobenthos, despite recent contributions to fish (Shah Esmaeili et al, 2022) and bird ecology (da Rosa Leal et al, 2013;Linhares et al, 2021;Rangel et al, 2022).…”