Fish mitigate trophic depletion in marine cave ecosystems

Abstract

Dark marine habitats are often characterized by a food-limited condition. Peculiar dark habitats include marine caves, characterized by the absence of light and limited water flow, which lead to reduced fluxes of organic matter for cave-dwelling organisms. We investigated whether the most abundant and common cave-dwelling fish Apogon imberbis has the potential to play the role of trophic vector in Mediterranean marine caves. We first analysed stomach contents to check whether repletion changes according to a nycthemeral cycle. We then identified the prey items, to see whether they belong to species associated with cave habitats or not. Finally, we assessed whether A. imberbis moves outside marine caves at night to feed, by collecting visual census data on A. imberbis density both inside and outside caves, by day and by night. The stomach repletion of individuals sampled early in the morning was significantly higher than later in the day. Most prey were typical of habitats other than caves. A. imberbis was on average more abundant within caves during the day and outside during the night. Our study supports the hypothesis regarding the crucial trophic role of A. imberbis in connecting Mediterranean marine caves with external habitats.

Behavioural traits and feeding ecology of Mediterranean lionfish and native species naiveté to lionfish predation

“…Such behaviour may then overlap and, through increased predation, impact the diel migrations of fish and crustacean species between caves and external habitats. Such migration provide an important source of nutrients to the relatively nutrient poor epibenthic communities in caves (Coma et al 1997, Bussotti et al 2018). The impact of Mediterranean lionfish preying on diel migrants may then have substantial consequences for the maintenance of such nutrient poor communities, increasing the likelihood of locally mediated losses of cave specific benthic communities.…”

Social flexibility to balance habitat fragmentation? Insights from the Mediterranean cave‐dwelling cardinalfish Apogon imberbis

“…Like other apogonids, it is a nocturnal fish feeding outside at night and spending the day in dark shelters in rocky cliffs, such as caves or crevices, where it can be found forming small groups or large swarms (Figure ) (Bussotti et al, ; Bussotti et al, ; Bussotti et al, ; Paxton & Eschmeyer, ; Raventos, ).…”

“…Several factors can explain such absence of genetic structure. First, it goes out of caves at night (Bussotti et al, ; Bussotti, Guidetti, & Belmonte, ). Second, besides brooding, it displays a pelagic larval phase of ca.…”

“…A. imberbis is not restricted to one form of social aggregation. It can be solitary in small crevice (Figure b) as well as in big swarms in large caves (Figure a) (Bussotti et al, ; Bussotti et al, ; Mazzoldi, Randieri, Mollica, & Rasotto, ). This ability to use a wide range of sizes of habitat patches, due to the high phenotypic plasticity in its sociality, is believed to contribute to balance the effect of habitat fragmentation on connectivity disruption of its populations (Muths et al, ).…”

3d Virtualization of an Underground Semi-Submerged Cave System

“…The natural and mystic beauty of such environments was recognized since long time, being also used by ancient civilizations for sacrificial offerings or aquatic cemeteries, such as the case of cenotes in the Maya civilization (Leshikar-Denton et al, 2016). Dark marine habitats, such as submarine caves, are often characterized by a food-limited condition, but still harbour remarkable biodiverse marine life (Bussotti et al, 2018;Rosso et al, 2018). As such, submerged and semi-submerged caves, filled with fresh and saltwater, constitute a unique heritage which needs special approaches for its 3D digitization and preservation.…”