Introduction Of Non-native Species Research Articles

Invisible dynamics: exploring the genetic diversity of peacock bass in Brazil

In Brazil, the introduction of non-native species into freshwater environments, such as peacock bass (Cichla spp.), was driven by aquaculture and sport fishing. These Amazonian fish possess phenotypic plasticity and resilience that facilitate their invasion and establishment in new habitats. Due to the taxonomic complexity of cichlids, studies on intraspecific variation are essential to mitigate the impacts of biological invasions. This study aimed to analyze the genetic diversity of peacock bass, assessing how invasive populations have diversified over time and across different regions in Brazil. Samples were collected from different invasive populations in Maranhão, São Paulo, Paraná, and Goiás. DNA was extracted and the 16S and COX1 genes were amplified. Ninety-seven specimens of the genus Cichla Schneider, 1801 were identified as Cichla monoculus Agassiz, 1831 (n=12); Cichla kelberi Kullander and Ferreira, 2006 (n=75); and Cichla piquiti (Kullander and Ferreira, 2006) (n=10). Sixteen 16S haplotypes (445bp) were identified, with haplotype diversity and nucleotide diversity values of Hd: 0.830 and Pi: 0.03777, respectively. The results showed proximity between the invasive populations from Maranhão and São Paulo, with haplotype sharing among Parque Nacional dos Lençóis Maranhenses, Baixada Maranhense, and Ilha Solteira. This highlights the fragility of species delimitation and definitions within the group, based solely on morphological data. By evaluating the set of morphological and genetic data, we found significant intraspecific variations, despite expecting population homogeneity due to the founder effect and bottleneck commonly observed in invasive populations. This underscores the adaptive potential of these cichlids.

Hybridization in the Anthropocene - how pollution and climate change disrupt mate selection in freshwater fish.

Chemical pollutants and/or climate change have the potential to break down reproductive barriers between species and facilitate hybridization. Hybrid zones may arise in response to environmental gradients and secondary contact between formerly allopatric populations, or due to the introduction of non-native species. In freshwater ecosystems, field observations indicate that changes in water quality and chemistry, due to pollution and climate change, are correlated with an increased frequency of hybridization. Physical and chemical disturbances of water quality can alter the sensory environment, thereby affecting chemical and visual communication among fish. Moreover, multiple chemical compounds (e.g. pharmaceuticals, metals, pesticides, and industrial contaminants) may impair fish physiology, potentially affecting phenotypic traits relevant for mate selection (e.g. pheromone production, courtship, and coloration). Although warming waters have led to documented range shifts, and chemical pollution is ubiquitous in freshwater ecosystems, few studies have tested hypotheses about how these stressors may facilitate hybridization and what this means for biodiversity and species conservation. Through a systematic literature review across disciplines (i.e. ecotoxicology and evolutionary biology), we evaluate the biological interactions, toxic mechanisms, and roles of physical and chemical environmental stressors (i.e. chemical pollution and climate change) in disrupting mate preferences and inducing interspecific hybridization in freshwater fish. Our study indicates that climate change-driven changes in water quality and chemical pollution may impact visual and chemical communication crucial for mate choice and thus could facilitate hybridization among fishes in freshwater ecosystems. To inform future studies and conservation management, we emphasize the importance of further research to identify the chemical and physical stressors affecting mate choice, understand the mechanisms behind these interactions, determine the concentrations at which they occur, and assess their impact on individuals, populations, species, and biological diversity in the Anthropocene.

Genome assembly of redclaw crayfish (Cherax quadricarinatus) provides insights into its immune adaptation and hypoxia tolerance

BackgroundThe introduction of non-native species is a primary driver of biodiversity loss in freshwater ecosystems. The redclaw crayfish (Cherax quadricarinatus) is a freshwater species that exhibits tolerance to hypoxic stresses, fluctuating temperatures, high ammonia concentration. These hardy physiological characteristics make C. quadricarinatus a popular aquaculture species and a potential invasive species that can negatively impact tropical and subtropical ecosystems. Investigating the genomic basis of environmental tolerances and immune adaptation in C. quadricarinatus will facilitate the development of management strategies of this potential invasive species.ResultsWe constructed a chromosome-level genome of C. quadricarinatus by integrating Nanopore and PacBio techniques. Comparative genomic analysis suggested that transposable elements and tandem repeats drove genome size evolution in decapod crustaceans. The expansion of nine immune-related gene families contributed to the disease resistance of C. quadricarinatus. Three hypoxia-related genes (KDM3A, KDM5A, HMOX2) were identified as being subjected to positive selection in C. quadricarinatus. Additionally, in vivo analysis revealed that upregulating KDM5A was crucial for hypoxic response in C. quadricarinatus. Knockdown of KDM5A impaired hypoxia tolerance in this species.ConclusionsOur results provide the genomic basis for hypoxic tolerance and immune adaptation in C. quadricarinatus, facilitating the management of this potential invasive species. Additionally, in vivo analysis in C. quadricarinatus suggests that the role of KDM5A in the hypoxic response of animals is complex.

Changes in fish species composition in the rivers of the Ararat Plain during the last century

Changes in fish species composition in the principal rivers of the Ararat Plain have been assessed over the last century through an analysis of the literature and field studies. A total of 39 fish species, spread across 12 families and 31 genera, have been documented across the Ararat Plain (Araks River basin within southern Armenia and northeast Turkey). In the Armenian section of the plain, 37 taxa have been recorded, including 12 non-native species. Over the past century, the number of fish species in the Metsamor River has increased from 15 to 23, and from 6 to 23 in the Hrazdan River. Currently 16 of the 21 native fish species, previously recorded, are still present in water bodies of the Armenian part of the plain. Rhinogobius cf. similis has been documented for the first time in this region. The primary reasons for the changes in the ichthyofauna composition in the Armenian part of the Ararat Plain are the introduction and subsequent spread of non-native species into reservoirs. This process involves species such as Rhodeus amarus, Knipowitschia caucasica, species of Gobio and invasive non-native species such as Pseudorasbora parva, Carassius gibelio, Rhinogobius lindbergi, R.cf. similis, and Oncorhynchus mykiss.

Interspecific differences in swimming performance, behavior and survival between native Italian gudgeon (Gobio benacensis Pollini, 1816) and non-native European gudgeon (Gobio gobio Linnaeus, 1758)

Introduction of non-native species is an important cause of biodiversity decline in rivers. Separated by mountains and salt water, the freshwater fish fauna in Italy has experienced a natural isolation from fish in continental Europe. As a consequence, several Italian fish species have diverged from their European sister species, likely with unique adaptations to the local environment. Relatedly, the region is also susceptible to the invasion of non-native fish, and today almost half the fish species present are of non-native origin. Several of these non-native species have Italian congeners susceptible to competition and hybridizations, and, in the long run, displacements and extinctions. One such example is the Italian gudgeon (Gobio benacensis) and its European congener European gudgeon (Gobio gobio). During the last few decades the European gudgeon was introduced in Italian waters and has since spread rapidly, causing progressive declines in the Italian species. As for several other similar species pairs, little is known about potential differences in ecology and behavior. Here we study differences between Italian and European gudgeons in a controlled laboratory environment, using a combined open field and provoked escape response test, as well as tracking their sympatric survival over time in the hatchery. The smaller Italian gudgeon displayed a lower maximum swimming speed compared to the larger European gudgeon. The Italian gudgeon also experienced substantially higher sympatric mortality, resulting in only European gudgeon surviving to the end of the experiment. Contrary to expectations, no difference was seen in boldness and the Italian gudgeon displayed a higher movement activity, moving a larger distance in an open field test, compared to its European sister species. The reported differences could play a role in the replacement process, and may also have impacts on the surrounding ecosystem, and the prey and predators that have coevolved with the Italian species.

Levels of Potentially Toxic and Essential Elements in Water and Estimation of Human Health Risks in a River Located at the Interface of Brazilian Savanna and Amazon Biomes (Tocantins River).

The Tocantins-Araguaia basin is one of South America's largest river systems, across three Brazilian states (Maranhão, Tocantins, and Pará), within the Legal Amazon region. Despite draining extensive Cerrado savanna and rainforest ecosystems, it has suffered significant degradation, notably in the past 40 years. Human activities, including agricultural expansion, deforestation, and the introduction of non-native species, have worsened the environmental damage, which is alarming since many residents and villages along the middle Tocantins River rely on it for water supply, recreation, and fishing. This study assessed the concentration of potentially toxic and essential elements in water samples from four sampling sites distributed along the middle Tocantins River. The monitoring occurred throughout 2023, involving the measurement of parameters both on-site and in the laboratory. Water quality and its health implications were evaluated using the Weighted Arithmetic Water Quality Index (WAWQI), the Water Quality Index (WQI), and the health risk assessment index. The levels of aluminum, copper, iron, magnesium, and selenium exceeded legal standards. Seasonal fluctuations indicate a complex dynamic influenced by climatic or seasonal factors, with February showing the highest values. Site P1, located in urban areas, exhibited elevated mean concentrations for conductivity, total dissolved solids (TDS), and chlorophyll, indicating the need for continuous monitoring. The nitrogen concentrations at P1 raise concerns regarding drinking water quality, which is a concern for the region's residents who use untreated river water. Despite seasonal variations in element concentrations, the overall WAWQI categorized all sections as "Excellent," and the WQI rated as "Good." Human health risk assessments detected no risks, but continuous monitoring and interventions are crucial for sustained water quality improvement.

Conservation genetics and status of Orania sylvicola palms in Singapore - native relicts or historical re-introductions?

Orania sylvicola (Griff.) H.E.Moore is a large, single-stemmed palm species widely distributed across Malesia. It is the only species of Orania present in Peninsular Malaysia and Singapore. In Singapore, the species is rare and critically endangered, although a full understanding of its distribution is hampered by sparse historical collections. However, conflicting records on the known localities in the literature, along with a recent discovery of a substantial population of Orania sylvicola within the Tyersall Learning Forest in Singapore Botanic Gardens, have led to questions on the origin of the extant populations of O. sylvicola. There are known instances of past introductions of non-native plant species in Singapore, which raised suspicions that some of the individuals were historical reintroductions from overseas. Genetic analyses, a comprehensive survey of existing literature and herbarium collections, and a topographical study of existing Orania sylvicola populations were carried out to determine the origin of these individuals in Singapore. Our results suggested that all Orania sylvicola individuals in Singapore are of native origin, with two populations present. The distribution of the two populations overlaps in the Singapore Botanic Gardens, which may indicate that some of the plants have been transferred to the Botanic Gardens from another location in Singapore. Preliminary results also revealed that sampled populations within Peninsular Malaysia and between Peninsular Malaysia and Singapore are highly differentiated from each other with very little gene flow either by pollen or seed dispersal. Our study highlights how the integration of genetic information, historical collections and topographical analyses can contribute to assessing the origin and conservation potential of endangered plant species in Singapore and provide insights into suitable conservation actions for Orania sylvicola.

Ancient and Recent Hybridization in the Oreochromis Cichlid Fishes.

Cichlid fishes of the genus Oreochromis (tilapia) are among the most important fish for inland capture fisheries and global aquaculture. Deliberate introductions of non-native species for fisheries improvement and accidental escapees from farms have resulted in admixture with indigenous species. Such hybridization may be detrimental to native biodiversity, potentially leading to genomic homogenization of populations and the loss of important genetic material associated with local adaptation. By contrast, introgression may fuel diversification when combined with ecological opportunity, by supplying novel genetic combinations. To date, the role of introgression in the evolutionary history of tilapia has not been explored. Here we studied both ancient and recent hybridization in tilapia, using whole genome resequencing of 575 individuals from 23 species. We focused on Tanzania, a natural hotspot of tilapia diversity, and a country where hybridization between exotic and native species in the natural environment has been previously reported. We reconstruct the first genome-scale phylogeny of the genus and reveal prevalent ancient gene flow across the Oreochromis phylogeny. This has likely resulted in the hybrid speciation of one species, O. chungruruensis. We identify multiple cases of recent hybridization between native and introduced species in the wild, linked to the use of non-native species in both capture fisheries improvement and aquaculture. This has potential implications for both conservation of wild populations and the development of the global tilapia aquaculture industry.

Unregulated introduced fish (Perca fluviatilis Linnaeus, 1758) is host to zoonotic parasites in a small Mediterranean island

Introduced species have a major impact on freshwater ecosystems, particularly on islands. Numerous fish species have been introduced in Corsica (Mediterranean island, southern France) as part of planned programs or clandestinely. The introduction of non-native freshwater fish species can have a range of impacts on the recipient ecosystem, including through the co-introduction of its pathogens. A sample of introduced perch Perca fluviatilis Linnaeus, 1758 from the artificial reservoir of Padula was examined following a report of parasites by an angler. The analyses revealed the occurrence of Eustrongylides sp. (Nematoda) and Clinostomum complanatum (Digenea), two zoonotic parasites in P. fluviatilis. Both parasites are reported for the first time in France. Eustrongylides sp. and C. complanatum may have been introduced with their fish intermediate hosts or through their final bird hosts. The occurrence of the two parasites raises concerns from both a veterinary and human health perspective as they can use a wide range of amphibians as intermediate hosts and can be acquired in humans through the consumption of raw or undercooked fish.

Half of global islands have reached critical area thresholds for undergoing rapid increases in biological invasions.

Biological invasions are among the threats to global biodiversity and social sustainability, especially on islands. Identifying the threshold of area at which non-native species begin to increase abruptly is crucial for early prevention strategies. The small-island effect (SIE) was proposed to quantify the nonlinear relationship between native species richness and area but has not yet been applied to non-native species and thus to predict the key breakpoints at which established non-native species start to increase rapidly. Based on an extensive global dataset, including 769 species of non-native birds, mammals, amphibians and reptiles established on 4277 islands across 54 archipelagos, we detected a high prevalence of SIEs across 66.7% of archipelagos. Approximately 50% of islands have reached the threshold area and thus may be undergoing a rapid increase in biological invasions. SIEs were more likely to occur in those archipelagos with more non-native species introduction events, more established historical non-native species, lower habitat diversity and larger archipelago area range. Our findings may have important implications not only for targeted surveillance of biological invasions on global islands but also for predicting the responses of both non-native and native species to ongoing habitat fragmentation under sustained land-use modification and climate change.

Assessing the role of non-native species and artificial water bodies on the trophic and functional niche of Mediterranean freshwater fish communities

Habitat alterations and the introduction of non-native species have many ecological impacts, including the loss of biodiversity and a deterioration of ecosystem functioning. The effects of these combined stressors on the community trophic web and functional niche are, however, not completely clear. Here, we investigated how artificial ecosystems (i.e. reservoirs) and non-native species may influence the trophic and functional niche space of freshwater fish communities. To do so, we used carbon and nitrogen stable isotope and abundance data to compute a set of isotopic, trait, and functional metrics for 13 fish communities sampled from 12 distinct ecosystems in Türkiye. We show that in reservoirs, fish were more similar in their trophic niche compared to lakes, where the trophic niche was more variable, due to higher habitat complexity. However, there were no differences in the trait and functional metrics between the two ecosystem types, suggesting a higher prey diversity than assumed in reservoirs. We also found that the number of non-native species did not affect the trophic niche space, nor the trait or functional space occupied by the fish community. This indicates that non-native species tended to overlap their trophic niche with native species, while occupying empty functional niches in the recipient community functional space. Similarly, the proportion of non-native species did not affect any trophic, trait, or functional metric, suggesting that changes in community composition were not reflected in changes in the community niche space. Moreover, we found that trait richness, but not functional richness, was positively related to the isotopic niche width and diversity, indicating that a wider occupied trait niche space corresponded with a wider occupied trophic niche and lesser interspecific similarity. Our findings underscore the complexity of ecological relationships within freshwater ecosystems and highlight the need for comprehensive management strategies to mitigate the impacts of human activities and biological invasions.

Water use of Guinea grass as affected by rainfed local conditions and practices in Sub-Saharan Africa

Ongoing efforts are currently being made to rehabilitate drought-affected pastures in Sub-Saharan Africa. One approach being explored is the introduction of non-native grass species, such as Megathyrsus maximus (Guinea grass). This study aims to investigate the water use of Guinea grass in semi-arid environments under rainfed conditions. Additionally, it aims to a better understanding of the variability of water use in Guinea grass through the utilization of the Bagging machine learning algorithm. Split-plot field experiments were carried out over two consecutive rainy seasons (2020-2021). The treatments included two in-situ rainwater harvesting practices, RWH (ridging plus terracing and terracing alone), three seeding rates, SR (1.5, 2.5, and 3.5 kg ha-1), and two soil nitrogen fertilization rates, SF (95 kg N ha-1 and 0 kg N ha-1). These treatments were compared to a control plot that involved zero-tillage, no fertilization, and no rainwater harvesting. The collected datasets were analyzed using R, SPSS 15, and spreadsheets. The results showed significant differences in plant indices and soil moisture content among the treatments. However, the treatments had insignificant effects on seasonal actual crop evapotranspiration (ETa), which ranged from 1.93 to 3.29 mm day-1. The interactions between SR and RWH were found to have significant impacts on water use. The Bagging algorithm revealed that the variability in ETa could be attributed to SR (42%), RWH (31%), and SF (26%), respectively. The implementation of rainwater harvesting practices resulted in a significant reduction in water usage, saving 86% of the green water used with a water footprint of 0.25 m3 kg-1, compared to 1.7 m3 kg-1 for no adoption of RWH conditions. The water use of rainfed Guinea grass was also found highly sensitive to dry spells. Further detailed studies using multiple-layer models are recommended to gain a better understanding of the non-linear interactions in semi-arid environments.

Anthropogenic Eutrophication Drives Major Food Web Changes in Mwanza Gulf, Lake Victoria

Discerning ecosystem change and food web dynamics underlying anthropogenic eutrophication and the introduction of non-native species is necessary for ensuring the long-term sustainability of fisheries and lake biodiversity. Previous studies of eutrophication in Lake Victoria, eastern Africa, have focused on the loss of endemic fish biodiversity over the past several decades, but changes in the plankton communities over this same time remain unclear. To fill this gap, we examined sediment cores from a eutrophic embayment, Mwanza Gulf, to determine the timing and magnitude of changes in the phytoplankton and zooplankton assemblages over the past century. Biogeochemical proxies indicate nutrient enrichment began around ~ 1920 CE and led to rapid increases in primary production, and our analysis of photosynthetic pigments revealed three zones: pre-eutrophication (prior to 1920 CE), onset of eutrophication with increases in all pigments (1920–1990 CE), and sustained eutrophication with cyanobacterial dominance (1990 CE–present). Cladoceran remains indicate an abrupt decline in biomass in ~ 1960 CE, in response to the cumulative effects of eutrophication and lake-level rise, preceding the collapse of haplochromine cichlids in the 1980s. Alona and Chydorus, typically benthic littoral taxa, have remained at relatively low abundances since the 1960s, whereas the abundance of Bosmina, typically a planktonic taxon, increased in the 1990s concurrently with the biomass recovery of haplochromine cichlid fishes. Overall, our results demonstrate substantial changes over the past century in the biomass structure and taxonomic composition of Mwanza Gulf phytoplankton and zooplankton communities, providing a historical food web perspective that can help understand the recent changes and inform future resource management decisions in the Lake Victoria ecosystem.

A Report on the Accidental Introduction of Asian House Gecko (<i>Hemidactylus frenatus</i> Duméril et Bibron, 1836) into the Heuksan Island of South Korea

Recently, as trade between countries has flourished, the sale of living creatures has become more active. In this process, whether intentional or not, the introduction of non-native species is increasing as well. When non-native species are intentionally introduced, the route is evident which enables swift management. However, when accidentally introduced, the management of non-native species is difficult, because the route of the introduction is unclear. In this paper, we report a non-native species introduced into a small island in South Korea. On July 17, 2020, a gecko species was found on Heuksan Island. Based on its external traits, the gecko was identified as Hemidactylus frenatus, one of the rapidly increasing invasive species in the world. The gecko was dead in a packed box upon discovery, 88 km from the nearest port, and about 320 km from Seoul, where the package was shipped from. This case is yet another evidence of how non-native species can be introduced to other countries and even islands.

Effects of oligotrophication and Dreissena littoral-pelagic coupling on littoral invertebrate and fish communities: insights from stable isotopes of archived samples

Changing nutrient concentrations and introduction of non-native species affect the energy and nutrient fluxes in aquatic ecosystems. As a response, invertebrate communities could be altered, and ‘novel’ trophic communities could develop. Lake Constance (Europe) experienced pronounced nutrient variation caused by cultural eutrophication (prior 1980s) and oligotrophication (post-1980) and experienced many neobiota invasions. We used archived samples to investigate the impact of oligotrophication and invasive species on carbon and nitrogen isotope signatures of littoral macroinvertebrates during spring and autumn periods from 2000 to 2015 and of littoral fish species in 2018. Isotopic signatures of invertebrate and fish species were in the same range and showed similar seasonal differences and clear patterns in respect to littoral vs pelagic food sources and trophic level. Oligotrophication did not strongly alter isotopic values and only δ15N values of invertebrates declined weakly with oligotrophication. In contrast, interannual variability of stable isotope signatures was related to abundances of the invasive Dreissena polymorpha suggesting interannual differences in the importance of benthic-pelagic coupling due to Dreissena pseudofaeces for the nutrition of littoral invertebrates. This study illustrates how stored samples can be used to detect the importance of oligotrophication and benthic-pelagic coupling on the stable isotope signatures of a benthic community.

A global analysis of the introduction pathways and characteristics associated with non-native fish species introduction, establishment, and impacts

BackgroundThe invasion success of introduced freshwater fishes is influenced by many factors, including ecological, species, and socioeconomic characteristics. Most studies that document the importance of these characteristics are conducted at local scales and/or focus on a single step of the invasion process. In this study, we aim to determine the species characteristics, ecological characteristics, and socioeconomic characteristics of non-native freshwater fish invasions. Our assessment was done at the global scale and considers all three steps of the invasion (i.e., introduction, establishment, and impact). For this purpose, we applied generalized linear models to 20 variables collected for 307 non-native species and modeled them as a function of ecological characteristics (i.e., environmental features), species traits (i.e., functional and morphological), and socioeconomic characteristics (i.e., human use and introduction pathways). We considered the number of countries in which each species was introduced, established, or had ecological impacts as a proxy of invasion step success. We also explored the specifics of species introduced through the aquaculture and the ornamental fish trade pathways.ResultsWe found that non-native freshwater fishes with broad diets, high parental care, and multiple introduction pathways are the most widely introduced and established worldwide. The number of countries with impacts reported was best explained by the type of introduction pathway (i.e., aquaculture or fisheries). Moreover, among non-native species introduced through aquaculture, those belonging to Cypriniformes and having broad diets were the most widely introduced and established species. In contrast, the species introduced through the ornamental fish trade pathway belonged to various taxonomic orders but were mainly native to tropical regions.ConclusionsConsidering several types of factors is important when analyzing the invasion success of freshwater fish and disentangling the different invasion steps. These findings have strong implications for anticipating the profile of species with a high potential to invade many countries.

Live‐bait industry as a pathway for movement of nonnative and invasive species: Implications for conservation of native Texas fishes

AbstractObjectiveLive‐bait species are widely used in recreational fishing throughout the United States. However, the use of invasive fish species as live bait has been identified as a common pathway for their introduction into aquatic ecosystems. We assessed the role that the live‐bait industry has in facilitating the introduction of nonnative and invasive species into Texas rivers. We focused on two invasive cyprinodontid species, the Sheepshead Minnow Cyprinodon variegatus and Gulf Killifish Fundulus grandis, which are believed to have been introduced into inland Texas rivers via bait‐bucket releases by anglers.MethodsWe conducted telephone and in‐person surveys of live‐bait shops in Texas on a seasonal basis (summer, fall, winter, spring) for 1 year. Locally owned bait shops and regional aquaculture facilities and hatcheries were included in the surveys.ResultSurveys did not reveal the presence of these invasive cyprinodontids in inland bait shops but did reveal the sale of nonnative Goldfish Carassius auratus and their black color morph, the black salty goldfish. Surveys conducted among inland and coastal live bait shops confirmed the sale of only one nonnative bait fish and six bait items native only to certain regions of Texas. Telephone surveys with aquaculture industry experts revealed that the aquaculture industry was also facilitating the movement of nonnative game and nongame fish species throughout the state.ConclusionGiven the potential for nonnative and invasive species to negatively affect recipient aquatic ecosystems, the continued distribution of such species within the aquaculture industry represents a potential threat in Texas. Our findings highlight the need for close monitoring of the live‐bait industry in the state to prevent further introductions into inland waters and reduce potential ecological risks to native fish populations and overall ecosystem functions and services.

Irrigation dams threaten Brazilian biodiversity.

Brazil is among the main contributors to global biodiversity, which, in turn, provides extensive ecosystem services. Agriculture is an activity that benefits greatly from these ecosystem services, but at the same time is degrading aquatic and terrestrial ecosystems and eroding Brazilian biodiversity. This conflict is growing, as emerging unsustainable legislative proposals that will benefit the agricultural sector are likely to accelerate the decline of biodiversity. One such initiative (Bill 1282/2019) would change Brazil's "Forest Code" (Law 12,651/2012) to facilitate construction of irrigation dams in Permanent Preservation Areas, a category that includes strips (with or without vegetation) along the edges of watercourses. Two other similar bills are advancing through committees in the Chamber of Deputies. Here we provide details of these three bills and discuss their consequences for Brazil's biodiversity if they are approved. Expected negative impacts with changes in the legislation include: increased deforestation; siltation; habitat fragmentation; introduction of non-native species; reduction in the availability of aquatic habitats; and changes in biogeochemical process. These proposals jeopardize biodiversity and may compromise the negotiations for an agreement between Mercosur and the European Union.

Non-native fish species as an important part of Zambia's food system: a case study of the Lake Kariba fishery

Fish have an important role in food systems of Zambia and are a cheaper source of animal protein, vitamins and minerals. Presently, fish catches are dwindling and many children and women in rural Zambia are malnourished because their diet consists mainly of maize, vegetables and legumes. The main component of the diet is nsima, a form of thick porridge prepared from maize flour, which provides energy as carbohydrates. This study was done to assess the impact of a non-native fish species (Oreochromis niloticus, Nile tilapia) which has both positive and negative impacts on Zambia’s food system, with particular reference to the Lake Kariba fishery. The study was based on a networked systems framework, achieved through the administration of questionnaires, interviewing 377 randomly selected respondents from the three areas of the lake (I, II and IV) and 156 respondents from 7 selected open fish markets. Focus group discussions (FGD) were done with women, men and youth, who were key informants. Analysis of results using chi-square analysis, which cross-tabulated variables were used to obtain the results. Non-native fish were introduced in the early 1980s for cage culture production in Lake Kariba but some fish accidentally escaped. This has changed the composition and abundance of fish species in the lake. Despite the negative ecological impact on native biodiversity, results showed that more fish are available to households, improving nutrition and disposable income from fish sales. The disposable income is used to purchase other foods, thereby reducing malnutrition among rural households. Thus, the introduction of appropriate non-native species might benefit households and the nation as a whole. Key words: Malnutrition, non-native fish species, Lake Kariba, Zambia, tilapia, Oreochromis niloticus

Trophic niche partitioning among non-native fish species coexisting in a Colombian high Andean reservoir

The introduction of non-native species to a new environment poses a threat to local biological diversity, causing instability in the functioning of the ecosystem. The ecological effects caused by these species have been scarcely documented in the Magdalena basin. By studying predator–prey interactions, we characterized the trophic niche of three non-native species (Cyprinus carpio, Micropterus salmoides, and Oncorhynchus mykiss) that dominate a high Andean reservoir in the Magdalena basin. This study allows us to understand their specific feeding behaviors and how these behaviors facilitate their establishment in the reservoir. We evaluated the diversity of the prey they consume, their feeding strategy, and possible differences in the feeding scheme. Forty individuals were analyzed, with the highest representation of M. salmoides with 17 individuals, followed by C. carpio (13 individuals), and finally O. mykiss with 10 individuals. We identified twenty categories of food as prey for these species, with aquatic invertebrates and vegetation material being the predominant prey. The analysis of stomach contents in these samples suggested that they are representative for determining specialized or generalist feeding strategies. There were no differences in the number of prey items consumed by these three species. The analysis revealed that the feeding strategies are specific for each species. There was no overlap in the diet of C. carpio with the other two species, however, the composition of the diet is similar between M. salmoides and O. mykiss. Analyzing the diet of these non-native fish provides a useful tool for describing trophic interactions in this aquatic environment. Our results contribute information on the existing interactions amongst non-native species in the Magdalena basin, which is important for the development of strategies to manage and mitigate their impact.