Luis Moreira da Costa

Urbanisation and water developments in South Africa have created numerous challenges in managing water resources. Consequently, the native fish species Oreochromis mossambicus, prominent to freshwater ecosystems in South Africa now faces the threat of extinction amidst introductions of alien Oreochromis species. The species has recently been classified as Vulnerable on the IUCN Red List. Despite the economic importance of O. mossambicus within the South African region, little is known about the genetic and population dynamics of the species. In this study, we aimed to establish baseline genetic and population data, and determine the impact of water management practices on population structure. This data is crucial for the conservation and monitoring of this species across South Africa. The study revealed relatively low genetic diversity within sample localities but significant differentiation among populations. The analyses identified 16 geographically correlated genetic clusters, indicating substantial differentiation across catchments. Anthropogenic activities, changes in catchment use, and water management strategies significantly influenced the genetic population structure in the studied regions. Given the distinct genetic patterns, conservation-oriented management should prioritise maintaining existing genetic diversity to ensure the long-term survival of this vulnerable species.

The recent surge in the discovery of hidden diversity within rheophilic taxa, particularly in West and East Africa, prompted a closer examination of the extent to which the current taxonomy may obscure the diversity of riffle-dwelling suckermouth catfishes in the genus Chiloglanis in southern Africa. Currently, the region comprises eight valid species within this genus. Seven of them have relatively narrow geographic distribution ranges except for C.neumanni, which is considered to be widely distributed, occurring from the Buzi River system in the south, and its northern limit being the eastward draining river systems in Tanzania. Recent surveys of the middle Zambezi River system revealed Chiloglanis specimens that were distinguishable from the known species of the genus from southern Africa. Integration of molecular and morphological data indicated that these specimens from the Mukwadzi River represent a new species to science, herein described as Chiloglaniscarnatus Mutizwa, Bragança & Chakona, sp. nov. This species is readily distinguished from its southern African congeners by the possession of a distinctive extended dermal tissue covering the base of the dorsal fin and the possession of ten mandibular teeth (vs 8, 12, or 14 in the other taxa). Results from this study add to the growing evidence of a high level of undocumented diversity within riffle-dwelling taxa in southern Africa.

Largemouth Bass (Micropterus salmoides, LMB) and Smallmouth Bass (Micropterus dolomieu, SMB) are among the most highly invasive species across the globe, but are simultaneously among the most highly sought-after game fish. To explain these disparate views, data on invasive status and angling participation of these two species were compiled at the country level. Largemouth Bass were found established in 62 countries on five continents, whereas SMB were found established in only nine countries on the same five continents. Invasive risk assessments were disparate between the species, with more for SMB (N = 29) than LMB (N = 27). In every instance save one (Finland), SMB were considered “invasive” compared to LMB, which were “invasive” in only 74% of assessments. Twenty-eight countries with non-native black bass have groups that participate in high-profile fishing tournament such the Black Bass World Championship, BASS (Bass Anglers Sportsmans Society) Nation, and Major League Fishing. Most countries with fishing tournaments occur in countries with established LMB populations than in countries with established SMB populations, suggesting a greater economic importance on LMB fishing. The struggle between conserving biodiversity and relying upon economic benefits from fishing for introduced species is a wicked problem likely to continue into the future.

Freshwater ecosystems are highly vulnerable to the detrimental impacts of both biological invasions and climate change. Piscivorous alien fishes drive populations of small-bodied native fishes to extinction and warming is already driving extreme temperature events in lakes and rivers globally. Here, we use Ecological Niche Modelling (ENM) to predict how climate change will alter the geographical space of six alien fishes and five native fish genera (which include multiple endemic species) in Turkey, a hotspot of freshwater fish diversity. The models predicted that the geographical space of the alien fishes already present in Turkey would generally increase (including pikeperch Sander lucioperca and perch Perca fluviatilis ), but with the most substantial increases in largemouth bass Micropterus salmoides , a species not yet present in Turkey but that is invasive in countries nearby and is highly popular for sport angling. For the native fish genera, general predictions were for reduced geographical space, especially in the south and east of the country, suggesting the endemic species will become increasingly imperilled in future. Their populations will also be at increasing risk of deleterious impacts from the alien piscivores, as the predictions were also for increasing overlaps in the geographical space of both the alien fishes and native fish genera. These predictions suggest that the conservation of these endemic species need to consider measures on preventing both the introduction of alien species (e.g. largemouth bass) and the further dispersal of extant alien species (e.g. pikeperch), as well as habitat interventions that will limit the effects of climate change on their populations. These results also indicate that the combination of climate change and alien invasions could have substantial impacts on—and similar—hotspots of freshwater diversity.

Aim We estimate and compare niche position, marginality and breadth of Iberian inland fishes at three geographical extents (regional, restricted to the species’ range and global) to understand the effect of spatial scale on niche metrics. Furthermore, we investigate differences in niche metrics between native and alien fish, and test for associations with introduction date of alien species and niche characterization to better understand their invasion process. Location Iberian Peninsula and global. Time period 2000–2020. Major taxa studied Fifty-one native and 17 alien inland fish species from the Iberian Peninsula. Methods Outlying mean index (OMI) analyses were used to estimate the niche position, marginality and breadth of Iberian inland fishes. Climatic OMI analyses were computed at three different scales (regional, restricted to the species’ range and global). Permutational analyses of variance (PERMANOVAs) were used to test for differences in niche position, marginality and breath among native and alien species. Results Niche metrics differed depending on the geographical extent of the investigation, as well as with respect to species origin (native versus alien). Differences in climatic niche position between native and alien species observed at the global scale were non-existent at the regional scale. The niche breadth of widely distributed alien species was highly underestimated when only considering the invaded region, and further influenced by the first date of of species introduction. Main conclusions Estimating niches of freshwater species, especially of alien invaders, should carefully consider the geographical extent of the investigation. We suggest that analyses that jointly consider regional and global scales will improve the estimation of niche metrics of widely distributed organisms, particularly regarding species climatic niche, and the assessment of the invasive potential of species.

An important driver behind introductions for aquaculture of alien fish species into Pacific Island Countries and Territories (PICTs) is a lack of knowledge about domestication suitability and specific culture requirements of indigenous taxa. Introductions may be appropriate in some circumstances, but in other circumstances, the associated risks may outweigh the benefits, so greater understanding of indigenous species' aquaculture potential is important. This review summarises literature for indigenous freshwater food fish species from Papua New Guinea, Fiji, Vanuatu, the Solomon Islands, Samoa and Tonga, and evaluates their aquaculture potential for food security and/or small‐scale livelihoods. A species selection criteria incorporating economic, social, biological and environmental spheres was used to score 62 candidate species. Tilapia (Oreochromis mossambicus and O. niloticus) now established in PICTs were evaluated for comparison. Results show that 13 species belonging to the families Mugilidae (Mullets), Terapontidae (Grunters), Kuhliidae (Flagtails) and Scatophagidae (Scats) have the highest culture potential according to selection criteria. These feed at a relatively low trophic level (are herbivores/detritivores), have comparatively fast growth rates and overall possess characteristics most amenable for small‐scale, inland aquaculture. The four top‐ranked candidates are all mountain mullets Cestraeus spp., followed by Nile tilapia (Oreochromis niloticus). Lower ranked candidates include three other mullets (Planiliza melinoptera, P. subviridis and Mugil cephalus) and rock flagtail Kuhlia rupestris. Importantly, many species remain data deficient in aspects of their reproductive biology or culture performance. Species profiles and ranked priority species by country are provided with logistical, technological and environmental assessments of country capacities to culture each species.

Four anguillid eel species occur in the western Indian Ocean rivers of Africa: Anguilla bengalensis, Anguilla bicolor, Anguilla marmorata and Anguilla mossambica. These catadromous fishes face multiple stressors, including habitat alteration and deterioration, barriers to migration, pollution and the adverse impacts of alien species, but knowledge of eel species occurrence, abundance and ecology in Africa remains poor.This study investigated the present and historical distribution of anguillid eels and the potential associated drivers of declines at the southern extremities of their ranges in South Africa. Data analysed included sampling conducted in KwaZulu–Natal and Eastern Cape between 2015 and 2020, and secondary data extracted from databases, museums and local management agencies.The median extent of inland penetration increased as follows: 22 km for A. bicolor, 29 km for A. marmorata, 94 km for A. bengalensis and 293 km for A. mossambica. The median altitude followed a similar pattern.Extent of occurrence analyses were carried out at the regional level in KwaZulu–Natal. The sampling data on present distribution (2015–2020), compared with historical data, suggests declines in the extents of occurrence of the four eel species in KwaZulu–Natal, ranging between 31 and 48% in the last 30 years and between 35 and 82% since the 1950s.With increasing human threats in the region, especially from watercourse modification and water abstraction, further declines for these species are expected. Conservation measures recommended include the maintenance or restoration of the ecological connectivity of important rivers and the implementation of freshwater protected areas. Although eels are at present not widely exploited in South Africa, there is a need for fisheries regulations to manage sustainable commercial exploitation.

Ecosystems face both local hazards, such as over-exploitation, and global hazards, such as climate change. Since the impact of local hazards attenuates with distance from humans, local extinction risk should decrease with remoteness, making faraway areas safe havens for biodiversity. However, isolat…

Addressing climate mitigation while meeting global electrification goals will require major transitions from fossil-fuel dependence to large-scale renewable energy deployment. However, renewables require significant land assets per unit energy and could come at high cost to ecosystems, creating pote…

Species distribution data are fundamental to the understanding of biodiversity patterns and processes. Yet, such data are strongly affected by sampling biases, mostly related to site accessibility. The understanding of these biases is therefore crucial in systematics, biogeography and conservation. …