Scavenger guild and consumption patterns of an invasive alien fish species in a Mediterranean wetland

Abstract

Invasive Alien Species (IAS) alter ecosystems, disrupting ecological processes and driving the loss of ecosystem services. The common carp Cyprinus carpio is a hazardous and widespread IAS, becoming the most abundant species in many aquatic ecosystems. This species transforms ecosystems by accumulating biomass to the detriment of other species, thus altering food webs. However, some terrestrial species, such as vertebrate scavengers, may benefit from dead carps, by incorporating part of the carp biomass into the terrestrial environment. This study describes the terrestrial vertebrate scavenger assemblage that benefits from carp carcasses in a Mediterranean wetland. We also evaluate the seasonal differences in the scavenger assemblage composition and carrion consumption patterns. Eighty carp carcasses (20 per season) were placed in El Hondo Natural Park, a seminatural mesohaline wetland in south‐eastern Spain, and we monitored their consumption using camera traps. We recorded 14 scavenger species (10 birds and four mammals) consuming carp carcasses, including globally threatened species. Vertebrates consumed 73% of the carrion biomass and appeared consuming at 82% of the carcasses. Of these carcasses consumed, 75% were completely consumed and the mean consumption time of carcasses completely consumed by vertebrates was 44.4 h (SD = 42.1 h). We recorded differences in species richness, abundance, and assemblage composition among seasons, but we did not find seasonal differences in consumption patterns throughout the year. Our study recorded a rich and efficient terrestrial vertebrate scavenger assemblage benefitting from carp carcasses. We detected a seasonal replacement on the scavenger species, but a maintenance of the ecological function of carrion removal, as the most efficient carrion consumers were present throughout the year. The results highlight the importance of vertebrate scavengers in wetlands, removing possible infectious focus, and moving nutrients between aquatic and terrestrial environments.

Outdoor recreation alters terrestrial vertebrate scavenger assemblage and carrion removal in a protected Mediterranean wetland

“…On the one hand, the lower consumption of carrion by vertebrates promotes increased carrion consumption by invertebrates, so that recycling of nutrients along the food web changes, since nutrients are incorporated into the lower levels of the food web (Melis et al ., 2007). In addition, vertebrates can transport nutrients over longer distances and move them between ecosystems, which makes them especially interesting in wetlands where they can play a key role in moving nutrients between the water–land interface by consuming fish carrion (Payne & Moore, 2006; Orihuela‐Torres, Pérez‐García, Sánchez‐Zapata, Botella, & Sebastián‐González, 2022; Orihuela‐Torres, Sebastián‐González, & Perez‐García, 2022). On the other hand, as carrion is available for longer, it benefits the populations of ‘feral’ species such as cats, dogs and rats, which are in contact with humans, therefore, increasing the probability of disease transmission, triggering not only health problems, but also large economic costs (Markandya et al ., 2008).…”

“…Waterbirds were placed near the ponds, fish on the shore of the ponds, and mammals and terrestrial birds throughout the Natural Park mimicking natural mortality. Carcasses were disposed all year round to account for possible seasonal differences in the scavenging patterns (Orihuela‐Torres, Pérez‐García, Sánchez‐Zapata, Botella, & Sebastián‐González, 2022), and at least 200 m apart. Some carcasses were placed at a closer distance (<25 m apart), but with at least 1 month of difference, to avoid scavengers getting used to the supply of carrion (Turner, Conner, & Beasley, 2020).…”

Condors scavenge on fish at the land–water interface in the Andean foothill of southern Bolivia

“…Consumption of fish carrion on land is a remarkable example of the aforementioned interaction that has been recorded in several biomes, involving several species of both scavengers and fish (Orihuela‐Torres et al., 2022; Schlacher et al., 2013). Raptors are conspicuous scavengers that include several species that scavenge facultatively, such as eagles (Accipitridae) and caracaras (Falconidae), and the only obligate scavengers, vultures (Cathartidae and Accipitridae), all of which can consume fish carrion as part of their diet (Ferguson‐Lees & Christie, 2001; Sazima, 2018).…”

Functional compensation in a savanna scavenger community

“…Also, many previous studies have focussed on vertebrate scavengers (e.g. Gerke et al., 2022; Orihuela‐Torres et al., 2022; Walker et al., 2021; reviewed in Beasley et al., 2019), or invasive scavengers (Abernethy et al., 2016; Angulo et al., 2011; Brown et al., 2015; Turner et al., 2021). However, our knowledge of the role the role of native invertebrate scavengers is relatively incomplete, particularly for certain ecosystems.…”