Fishes have been introduced in non-native ecosystems all over the world. These introductions have been recognised for their overall negative effects on native biodiversity. Plecos (Pterygoplichthys Gill, 1858) have been introduced worldwide due to bad practices in the aquarium trade and, in Central America, there is little information regarding these invasive fishes. Plecos have been demonstrated to be a threat in non-native ecosystems because they interfere with their new ecosystems through bottom-up impacts, altering nutrient availability and interactions with native wildlife. Herein, new records of plecos are reported for river basins from Guatemala in northern Central America where they had not previously been reported. Evidence of interactions of plecos with the native fauna that had not been recorded to date are also included. We compiled a total of 34 records in Guatemala, with eight new records. We present the first records of the genus in a river basin of the Caribbean drainage for Guatemala. Three new interactions of fauna preying upon plecos are presented (Black vulture, Bare-throated tiger Heron and Domestic dog), along with a compilation of previously known interactions. Establishing a monitoring and surveillance programme should be a priority in Guatemala, along with other actions to safeguard the native wildlife that could be at high risk because of biological invasions, such as the one with plecos. In order to better understand this invasion, joint efforts of local fishermen and rangers with State institutions should be promoted.

biological invasions, Central America, dispersion strategies, exotic fish, non-native fauna, river basins, threatened ecosystems

Fishes have historically been introduced in non-native ecosystems all over the world for several purposes, including sport and food fisheries, as well as biocontrol and as an effect of the aquarium trade (Pípalová 2006; Rahel 2007; Walsh et al. 2016). However, many of these introductions have been recognised for their negative effects on native biodiversity (Moyle and Light 1996; Vitousek et al. 1996; Eby et al. 2006; Gozlan et al. 2010; Alexiades et al. 2017). Suckermouth armored catfishes, “peces diablo” or “plecos”, Pterygoplichthys Gill, 1858 is a genus of fishes that belong to the family Loricariidae, which are naturally distributed in southern Central America and in South America, but their diversity is higher in the latter (Armbruster 2004). These species have been introduced worldwide due to bad practices in the aquarium trade, where they are popular (Orfinger and Goodding 2018). Releases for the genus have been reported in southern Mexico that led to a later invasion in Guatemala, where two species have been recorded: P. pardalis Castelnau, 1855 and P. disjunctivus Weber, 1991. Visual morphological and colouration characters conventionally used to identify species of the genus present “intermediate states” that make accurate taxonomic recognition of these two species difficult, and hybridisation has been suggested, either previously in aquarium trade or directly in the introduced regions (Orfinger and Goodding 2018).

In Guatemala, the Guatemalan System of Protected Areas (SIGAP, by its acronym in Spanish) is responsible for the management and conservation of protected areas and biodiversity. The SIGAP is made up of over 300 protected areas (31% of Guatemalan territory), where there are six management categories, based on the foci for conservation (Conap 1999). The largest continuous protected area complex in the SIGAP is the Maya Biosphere Reserve (MBR) in northern Guatemala, that, along with other protected areas from southern-northern Guatemala, southern Mexico and north-western Belize, make up the so-called Selva Maya (SM), which comprises the largest protected area complex in Central America and the largest continuous patch of tropical forest in the Neotropics after the Amazon Forest (Conap 2015). The MBR belongs to the Biosphere Reserve category, which considers multiple actions and activities, both cultural and biological (Conap 2015). These actions and activities define the administration of the MBR in its different management categories: Core Zones (National Parks and Protected Biotopos), Multiple-use Zone (Forestry and Community Concessions and Biological Corridors) and a Buffer Zone (Radachowsky et al. 2012). In addition to the MBR, there are other protected areas in northern Guatemala that seek to preserve natural ecosystems and processes. The hydrology of this area is determined by karst conditions and the headwaters of two international drainage systems are formed here, although approximately 80% of the extension of the MBR belongs to the Usumacinta drainage.

Different non-native fishes have been reported in the MBR and surrounding areas, including Pterygoplichthys plecos (Quintana and Barrientos 2012; Penados-Saravia 2014; Sánchez et al. 2015; Ariano-Sánchez et al. 2017; Barrientos et al. 2018). Introduced species like Pterygoplichthys spp. have been shown to interfere with invaded ecosystems through bottom-up alterations and creating “nutrient hotspots” (Capps and Flecker 2013, 2015; Capps et al. 2014). Despite efforts to manage these species and their effects, non-native and invasive species continue to be recognised as one of the main threats to biodiversity and one of the main causes of global change through biotic exchange and homogenisation (Sala et al. 2000; Rahel 2002; Garcia-Berthou 2007). In order to document the spread of non-native plecos in northern Guatemala, Central America, the main objective of this paper is to report new records for river basins. We also include evidence of interactions between plecos and the native fauna in the MBR that had not been recorded to date.

We found 26 previous records for the distribution of Pterygoplichthys spp. in Guatemala, in the La Pasión, Salinas, San Pedro and Usumacinta River Basins, draining to the Gulf of Mexico. Eight records have voucher specimens (LSUMZ 16833, 16486, 16487; USAC 2258, 2264, 2263, 2262, 2261), 17 come from grey literature (Penados Saravia 2014) and only one record is a photographic record found in published literature (Ariano-Sánchez et al. 2017) (Fig. 1). We report eight new distributional records of Pterygoplichthys in Guatemala (see Fig. 1), which sums to a total of 34 records in the country (see Suppl. material 1: Table S1). The first record is a photograph of an individual found alive over a mud trail, from ELMU in 2017 (northernmost record in Guatemala, Fig. 2). Three more records were found in the Holmul River from the Mopán-Belize River Basin, which drains into the Caribbean, from two photographs obtained from CDC-CECON research team by direct observation of dead individuals on banks of the Holmul River in YNNNP during the dry seasons of 2018 and 2019 (Fig. 3) and another based on a photograph recorded by camera-trapping during the dry season 2018 (Fig. 4). Two more records come from observations in the La Pasión River transect between ECNP and Nueva Canaán (Fig. 5). The remaining two records belong to unpublished data (Cano Alfaro, unpublished data) we found in the CDC-CECON database, where two plecos are reported. In 2009, park rangers found and deliberately killed one individual in TNP and another in SMPZPB (Suppl. material 2: Figure S1), as they recognised them as an invasive species.

Figure 2. 

Direct observation of alive Pterygoplichthys sp. individual crawling in a muddy trail in El Lechugal Management Unit, Maya Biosphere Reserve, Guatemala.

Figure 3. 

Direct observation of Pterygoplichthys sp. individuals during dry season 2018 (A, B) and 2019 (C) in banks of Holmul River, Yáxha Nakum Naranjo National Park, Maya Biosphere Reserve, Guatemala.

We report new predation and carrion consumption interactions of plecos in Guatemala from different species (Table 1) in three sites (Fig. 1). In the Holmul River, we report a Bare-throated tiger Heron (Tigrisoma mexicanum Swainson, 1834) preying on a pleco, based on a photograph recorded by camera-trapping (Fig. 4). In La Pasión River, we report the Olivaceous Cormorant (Phalacrocorax brasilianus Gmelin, 1789) as a pleco predator, based both on field observations and photographs (Fig. 5) and the Neotropical Otter (Lontra longicaudis Major, 1897) as a pleco predator, based solely on field observations. Added to this, we report direct observations of individuals of black vultures (Coragyps atratus Buchstein, 1793), domestic dogs (Canis lupus familiaris Linnaeus, 1758) and Morelet’s Crocodile (Crocodylus moreletii Duméril & Bibron, 1851) feeding on pleco carcasses (scavenging) on the banks of La Pasión River. The Olivaceous Cormorant was observed as the most abundant bird species in the segment of the La Pasión River, with groups of over 50 individuals resting on the river beach and surrounding vegetation.

Figure 4. 

Predation of Pterygoplichthys sp. by a Bare-throated tiger Heron Tigrisoma mexicanum in Holmul River, Yaxhá Nakum Naranjo National Park, Maya Biosphere Reserve, Guatemala.

Figure 5. 

Predation of Pterygoplichthys sp. by an Olivaceous Cormorant Phalacrocorax brasilianus in La Pasión River, Guatemala. Visible ventral (A) and (B) dorsal view of pleco.

While the presence of plecos is widely known in the territory of Guatemala by local people, formal records are still scarce, especially those with voucher specimens. Although the number of records we compiled is low, we believe that this represents under-sampling due to the lack of a monitoring and surveillance programme that shows the progress of this invasion. Recording the presence of plecos in both the San Pedro (northernmost record in Guatemala) and Mopán-Belize River Basins leaves the Río Hondo River Basin as the only one without confirmed records in northern Guatemala. However, plecos have been recorded in the Mexican and Belizean sides of the Río Hondo River Basin (Schmitter-Soto et al. 2015). It is important to note that the Moho and Temash River Basins, both in the Petén department, remain without records of plecos in Guatemala. We also emphasise the importance of the Usumacinta drainage, which covers most of the territory of the MBR with surface water that drains to the Gulf of Mexico. In total, four out of seven river basins of the Usumacinta drainage in the Guatemalan side now have records of plecos.

Despite the lesser covered area in the MBR and northern Guatemala compared to the Gulf of Mexico drainage, the Caribbean drainage now shows the Mopán-Belize River Basin with records of plecos in YNNNP, leaving Río Hondo, Moho and Temash River Basins vulnerable to further invasions. This national park is one of the Core Zones most prone to threats within the MBR, as it is located on the southern border of the reserve close to towns in the Buffer Zone, as well as being prone to illegal hunting, fires and encroachment (Conap 2015). On the other hand, recording the presence of plecos in YNNNP would imply a direct threat due to the hydrological priority of this area for conservation in having important water-bodies, such as the Holmul and Naranjo Rivers, as well as the Yaxhá, Sacnab and Lancajá lagoons and numerous aguadas (Cecon 1996). This is the case of aguadas, which correspond to temporary or seasonal ponds that form from depressions in the SM karstic landscape within higher clayey soil composition, allowing the capture of rainwater during the rainy season (Reyna-Hurtado et al. 2010). The importance of available surface water in these systems is particularly highlighted during the dry season, given the temporal climate variation that causes water shortage.

The under-sampling of plecos and lack of a unified compilation of the genus is evident as unpublished data show. Plecos recorded and killed in TNP and SMPZPB by rangers during park patrols correspond to data that were unknown for more than a decade until our search and query for available records of plecos in Guatemala using the CDC-CECON database. Furthermore, this demonstrates that the knowledge of plecos by the local people in Guatemala is well known, to such an extent that the inhabitants themselves take measures to try to control and reduce the populations of these invasive fish (see Supplementary Fig. 1). Additionally, together with the new records of plecos in YNNNP, it is important to note that plecos have been recorded in this area in the last 10 years (now two years in a row just in YNNNP), which may show that plecos have been established in the Holmul River and within the Mopán-Belize River Basin. The importance of TNP and SMPZPB, together with YNNNP, is of great interest to conservation of the SM. These protected areas comprise the southern border of the MBR and are currently facing higher risks and threats due to the advancing agricultural frontier, extraction of precious woods, poaching, as well as forest fires (Cecon 1996; Conap 2015). There is now the added pressure of this biological invasion.

The success of the rapid spread and establishment of invasive populations of plecos worldwide is due to their easy adaptation and high breeding and survival rates in new environments (Armbruster 1998; Liang et al. 2005; Page and Robins 2006; Bijukumar et al. 2015), along with possessing morphological characteristics that hinder their predation by natural and indigenous predators in new places (Ebenstein et al. 2015; Orfinger and Goodding 2018). Regarding these characteristics, we suggest that the ability to withstand extreme droughts (Armbruster 1998) by surviving in muddy environments (away from water bodies) represents a new strategy for their success in colonising new areas and future population establishment. The new report at ELMU in a locality where superficial water is only seasonally available, as in northern Guatemala, demonstrates a plausible explanation for their dispersal in these environmental conditions (Fig. 2). Similarly, plecos show a tolerance for high salinity changes (Capps et al. 2011). This strategy is added to the possibility of hybridisation in Pterygoplichthys spp., that may be responsible for many recorded plecos showing intermediate phenotypic states (Fig. 3), but this still has not been demonstrated using molecular data (Orfinger and Goodding 2018).

The effect that plecos have on the water quality and river nutrients has been explored in the region (Capps and Flecker 2013, 2015; Capps et al. 2014) and is ongoing in Guatemala (Quintana, Y., comm. pers.). However, no formal records of their direct interactions with local fauna have been described in Guatemala. Herein, we compiled 13 species predating on plecos outside their native range (Table 1), where we recorded two of them (Phalacrocorax brasilianus and Crocodylus moreletii) in Guatemala. Additionally, we report three new species predating and scavenging on plecos (Tigrisoma mexicanum, Coragyps atratus and Canis lupus familiaris), increasing the list of pleco predators in non-native environments to 16 species. Knowing these interactions is highly important in discussions about the management plans that should be initiated regarding plecos in Guatemala. The effects of plecos are already being noticed, as the niche breadth and the trophic level of the Neotropical Otter have been altered (Juarez-Sanchez et al. 2019) and this should be assessed with the additional species that we report.

Plecos have spread over the region in a little more than 10 years and are now spreading into new drainage systems and river basins (Kihn-Pineda and Cano 2012), even in river basins not connected with others where the genus was previously known (Lardizabal et al. 2020). Given the importance of the MBR for conservation in northern Central America, these new records should be taken into account for conservation priorities and management actions. Considering that this is one of the most pristine and important conservation areas in the Neotropics, the presence and strengthening of State institutions in the area must be prioritised. Additionally, the involvement of local and small-scale fisheries that might be threatened due of the presence of plecos (Orfinger et al. 2019) should lead the collaborative work between fishermen, the Fishing Agency (DIPESCA-Dirección de Normatividad de la Pesca y Acuicultura) and Environment Ministry (MARN-Ministerio de Ambiente y Recursos Naturales). Local fishermen and park rangers recognise plecos as a non-native and invasive species in Guatemala and, because of this, they deliberately kill and discard the individuals when they are caught while fishing and during park patrols, respectively. Although fishermen and park rangers acknowledge plecos as an invasive species and actively try to reduce their populations, State institutions should accompany their efforts. An example of these actions is the proposal to use plecos for consumption purposes, either directly or in the production of flour as a dietary supplement for stock of other animal species of regular consumption (Filigrana Celorio 2016; Ixquiac 2016; Fonseca-Hernández and Vargas-Alpízar 2018). These actions should highlight the best way to work and solve this ecological problem.

Although the presence of plecos in many water-bodies in Guatemala is well known, there is still no precise information about the current distribution status of these invasive fish and in what other ecosystems we find them. There are very few published records, such as those presented in this study. We identified predation interactions of plecos, with three new species feeding on them. More sampling efforts are necessary to better understand the invasion of plecos in northern Central America and it is a priority to generate actions to safeguard the native wildlife that could be at high risk due to this biological invasion. In addition, knowing that withstanding droughts in environments far from water-bodies (crawling in muddy trails) is a dispersion strategy for this fish, the seasonality and availability of usable surface water in the MBR will not be an obstacle for this invasive species to continue colonising and impacting the native wildlife of Guatemala and other areas of the Neotropics.

Funding for fieldwork on this publication was provided by the IUCN Tapir Specialist Group and Fondation Segré World Tapir Conservation Programme through the CECON and Fundación Defensores de la Naturaleza -FDN- Baird’s Tapir Conservation Program & Dirección General de Investigación of the San Carlos University -DIGI/USAC- (project 4.8.63.2.35 implemented in 2018). We are very grateful to the FUNDAECO/CONAP rangers who recorded the pleco in El Lechugal, especially to Francisco Asturias for providing the information and to Jerson Olivares and Miguel Caal for taking the data on the field. We also thank researchers of CDC-CECON of San Carlos University for the data collection in Yaxhá Nakum Naranjo National Park: M. Gabriela Cajbon-Vivar, Vivian. R. González-Castillo and Gerber D. Guzmán-Flores. To Yaxhá Nakum Naranjo National Park staff and rangers for facilitating the entrance to the areas and accompanying the data collection, especially to Jorge M. Vásquez, Leonel Ziesse and A. Lorena Lobos. We thank Caleb McMahan for reviewing the English writing of this publication. We are very thankful with the two reviewers, who contributed with important comments and suggestions to improve this publication.