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Papers by Nic Pacini

Freshwater Ecology and Conservation

Chemical equilibria in surface waters stem from complex interactions between physical background ... more Chemical equilibria in surface waters stem from complex interactions between physical background and living components of ecosystems. Catchments differ in geological background, climate, and land use; their run-off bears a distinctive chemical ‘fingerprint’. This chapter illustrates how the monitoring of standard parameters, such as oxygen, pH, conductivity, major ions, nutrients, and carbon, can lead to an interpretation of key aspects of the functioning of major ecosystem processes and how chemical constituents may affect the distribution of aquatic organisms. This requires understanding principles that underlie available measurement techniques and it demands a certain familiarity with the intrinsic variability of parameter values and of their chemical interaction. It is not required that field scientists be able to conduct detailed chemical assessments, but all should be able to collect samples yielding high-quality data. Therefore, detailed advice on chemical monitoring practice...

Water

Little is known about the quantity and quality of dissolved organic matter (DOM) in waters from c... more Little is known about the quantity and quality of dissolved organic matter (DOM) in waters from continental geothermal systems, with only a few reports available from the Yellowstone US National Park. In this study, we explored the chemodiversity of DOM in water samples collected from two geothermal hot springs from the Kenyan East African Rift Valley, a region extremely rich in fumaroles, geysers, and spouting springs, located in close proximity to volcanic lakes. The DOM characterization included in-depth assessments performed by negative electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Reduced, saturated and little aromatic DOM compounds were dominant in the hot spring waters collected from either the Ol Njorowa gorge (ON) or the south shore of the soda-saline Lake Elementaita (ELM). Oxygen-poor and sulfur-bearing DOM molecules prevailed in ON, probably reflecting abiotic sulfurization from sulfide-rich geofluids. Nitrogen-bearing a...

Lake Naivasha, a shallow tropical lake in Kenya’s Rift Valley, has an unstable water column and i... more Lake Naivasha, a shallow tropical lake in Kenya’s Rift Valley, has an unstable water column and is moderately eutrophic. Nutrient (bottom-up) control of primary production is more important than grazing (top-down) con-trol. Experimental nutrient enrichment was used to investigate bottom-up control in more detail. Minor nutrients were not found to be limiting, whilst nitrogen was more limiting than phosphorus with an algal preference for ammonium over nitrate. Sediments form a phosphorus sink but there is hypolimnetic release from the one area showing regular temporary stratification. This indicates that the rate of primary production in the water column could double if conditions change to allow lake-wide nutrient release from sediments. Both external and recycled nutrient regeneration are important.

African Journal of Ecology, 2021

Communications Biology, 2021

The contribution of oxic methane production to greenhouse gas emissions from lakes is globally re... more The contribution of oxic methane production to greenhouse gas emissions from lakes is globally relevant, yet uncertainties remain about the levels up to which methanogenesis can counterbalance methanotrophy by leading to CH4 oversaturation in productive surface waters. Here, we explored the biogeochemical and microbial community variation patterns in a meromictic soda lake, in the East African Rift Valley (Kenya), showing an extraordinarily high concentration of methane in oxic waters (up to 156 µmol L−1). Vertical profiles of dissolved gases and their isotopic signature indicated a biogenic origin of CH4. A bloom of Oxyphotobacteria co-occurred with abundant hydrogenotrophic and acetoclastic methanogens, mostly found within suspended aggregates promoting the interactions between Bacteria, Cyanobacteria, and Archaea. Moreover, aggregate sedimentation appeared critical in connecting the lake compartments through biomass and organic matter transfer. Our findings provide insights into ...

27 The meat of wild animals (bushmeat) is consumed extensively in many tropical regions. 28 Over ... more 27 The meat of wild animals (bushmeat) is consumed extensively in many tropical regions. 28 Over the past few decades bushmeat consumption has greatly increased, threatening the 29 survival of some hunted species and the supply of animal protein to countless numbers of 30 people. Understanding patterns of bushmeat consumption is thus vital to ensure the 31 sustainable use of this resource. Although the economic drivers of bushmeat consumption 32 have been well studied, non-wealth correlates have been poorly considered. Here, we 33 analyse how variables such as age and gender may influence bushmeat consumption in 34 four West African countries, within the Guinean forests (Togo and Nigeria) and Sahel 35 (Burkina Faso and Niger). We interviewed a total of 2,453 persons (1,253 urban, 1,200 in 36 rural areas) to determine frequency of consumption of bushmeat as well as the main 37 species eaten. We found significant differences in bushmeat consumption between rural 38 and urban areas in ...

Herpetological Journal, 2018

The forest hingeback tortoises Kinixys homeana and Kinixys erosa are two of the most declining Af... more The forest hingeback tortoises Kinixys homeana and Kinixys erosa are two of the most declining African chelonians. Although the population size trends of these species have received attention in some specific areas of West Africa, an overall perception of their declining trajectories are still largely unexplored. We used interviews with rural people (hunters, farmers and snail gatherers) in order to explore the general perception that these experienced people have on the population trends of these threatened tortoises. Overall, we interviewed over 2000 people in three West African countries (Côte d’Ivoire, Togo and Nigeria), which mostly supported the notion that these tortoises are heavily declining in Togo and Nigeria, but less so in Côte d’Ivoire. In addition, many respondents suggested that snail gatherers are the main providers of tortoises to the bushmeat trade. Indeed, our market surveys revealed that, in Nigeria, there was a significantly positive correlation between number ...

Tropical Ecology, 2016

The bushmeat trade in West and Central Africa embraces a broad range of ecological, economic, and... more The bushmeat trade in West and Central Africa embraces a broad range of ecological, economic, and conservation issues. To date, most studies have focused on the economic and conservation aspects of the bushmeat trade, with less emphasis on the ecological implications of wildlife extraction. Here, we analysed available literature on the bushmeat trade in 5 countries in west and central Africa exploring ecological traits such as niche width breadth and trophic position of the species involved, and habitats impacted. We also examine temporal changes over a 40-year period. Our results confirm that mammals dominated the trade in all studied areas and time periods, in terms of (i) number of species, (ii) number of traded individuals, and (iii) overall biomass. Herbivores were the most common trophic animal guild traded. Forest-specialists were the most abundant in the trade, and in riverine habitats reptile biomass almost as important as mammals. Overall, the most traded species and indiv...

Despite increasing pressures on freshwater resources worldwide, and the threatened status of most... more Despite increasing pressures on freshwater resources worldwide, and the threatened status of most freshwater turtles, there is still limited knowledge of habitat use and niche partitioning in Afrotropical freshwater turtle communities. In this study, we describe habitat associations, community diversity, and temporal patterns of occurrence of freshwater turtle species in the Dahomey Gap ecoregion of Ghana (West Africa). We gathered data from 13 sites in central Ghana and along the Sene Arm of Lake Volta in the Digya National Park (Bono East Region). We employed opportunistic short-term surveys (at seven sites) together with longer-term (six-months duration) standardized evaluations of turtle presence and numbers in different habitats (at six sites). In addition, we interviewed fishers in the Lake Volta area to explore their perception about turtle abundance trends. Overall, 210 turtle individuals belonging to four species (Trionyx triunguis, Cyclanorbis senegalensis, Pelomedusa sp. ...

European Journal of Ecology, 2021

A survey conducted in Terekeka, Mongalla (=Mongalla) and Gemmaiza (= Gemeiza), payams of Central ... more A survey conducted in Terekeka, Mongalla (=Mongalla) and Gemmaiza (= Gemeiza), payams of Central Equatoria in South Sudan using face-to-face interviews, structured questionnaire and focused group discussion provided information on income generating strategies of fishing communities. These included: full time or part time fishing, small-scale farming, cattle breeding and firewood collection. Stationary gill nets were the dominant type of fishing gear, followed by monofilament, hook and long line, cast nets, spears and harpoons. Fishing vessels included planked canoes, steel boats and fibreglass. The best fishing months were August, September, followed by May. Main species caught included large bodied potamodromous predators adapted to channel habitats, as well as floodplain migrants. Overall the fish community appeared to be at equilibrium, with no evidence of impacts due to excessive catch efforts. The good health of the White Nile fishery is related to the high resilience of South...

Ecohydrology & Hydrobiology, 2018

The volcanic and tectonic lakes of the eastern branch of the African Great Rift Valley are expose... more The volcanic and tectonic lakes of the eastern branch of the African Great Rift Valley are exposed to multiple stressors and characterised by different levels of hydrological connectivity. Past volcanic activity generated endorheic basins, in which the nature of the bedrock, its connection with groundwater, and local climatic conditions, favoured the formation of highly alkaline soda waters. While little is known about their nutrient dynamics, most lakes in this area experience considerable microbial blooms and harbour diverse and specifically adapted microbial populations, some of which could embody novel biotechnological potential. Here we review the geochemical and (micro)biological features of a cluster of lakes distributed within the East African Rift, ranging from fresh to hypersaline, under different levels of hydrological connectivity. Possibly no other location on Earth has a comparable range of lake types in close proximity to each other and representing such a remarkable microbial biodiversity. Environmental heterogeneity and habitat connectivity among adjacent aquatic ecosystems may have positive implications in terms of regional environmental stability by enhancing the overall carrying capacity, i.e. the resilience to various forms of impact, contributing to biodiversity protection. Within these ecosystems, microbial processes encompass the entire basis of their primary production, in particular those driven by cyanobacteria. Combining a multidisciplinary ecohydrological approach with a biogeochemical investigation of the principles underlying their functioning, our study can contribute to the development of appropriate environmental protection measures to effectively maintain their natural capital.

Acta Oecologica, 2019

The meat of wild animals (bushmeat) is consumed extensively in many tropical regions. Over the pa... more The meat of wild animals (bushmeat) is consumed extensively in many tropical regions. Over the past few decades bushmeat consumption has greatly increased, threatening the survival of some hunted species and the supply of animal protein to countless numbers of people. Understanding patterns of bushmeat consumption is thus vital to ensure the sustainable use of this resource. Although the economic drivers of bushmeat consumption has been well studied, non-wealth correlates have been poorly considered. Here, we analyse how factors such as age and gender influence bushmeat consumption in four West African countries, within the Guinean forests (Togo and Nigeria) and Sahel (Burkina Faso and Niger). We interviewed a total of 2,453 persons (1,253 urban, 1,200 in rural areas) to determine frequency of consumption of bushmeat as well as main species eaten. We found significant differences in bushmeat consumption between rural and urban areas in all four countries. In particular, the proportion of persons not consuming any bushmeat was highest in urban areas. Gender differences in bushmeat consumption was not generally important but young people consistently avoided eating bushmeat, especially in Togo and Nigeria, and in urban areas. The complicated interplay between tradition and evolution of social systems (especially the trends towards westernization) may explain the different perceptions that people may have towards consuming bushmeat in the four studied countries. In addition, we found considerable variation in types of bushmeat eaten, with antelopes and large rodents eaten by the great majority of interviewees, but bats, monkeys, and snakes being avoided, especially in urban settlements.

Acta Oecologica, 2017

Little is known about fish diversity in the coastal streams southeastern Nigeria in this world-re... more Little is known about fish diversity in the coastal streams southeastern Nigeria in this world-renowned biodiversity hotspot. In these ecosystems, the combination of seasonal changes in hydrology as well as the presence of coastal forests provides a greater biotope diversity, food and shelter for many fish species. Currently, however, deforestation, pollution and exotic species invasions impact the system's hydrology, water quality ultimately changing fish assemblage composition. In this paper, we describe the current status of fish diversity in the forested coastal streams of southeastern Nigerian based on recent collections and data drawn from selected scientific publications. We found a total of 88 fish species from 27 families in 10 orders.. Fish assemblages were generally characterised by a low evenness, with 90% of specimens belonging to over a quarter of the overall number of taxa, and strongly dominated by species of aquaculture interest, such as tilapiine cichlids. The studied stations had a high heterogeneity and noncomparable diversity profiles; stressing the role played by local conditions. Stations closer to the River Niger Delta differed significantly from the remaining large relatively homogeneous cluster. We found that the spatial turnover components of b-diversity were significant, and this was related to longitudinal distance, and not to species replacement by ecological vicariants. The observed species composition and the diversity patterns are consistent with a scenario whereby an originally high biodiversity is being eroded because of habitat degradation and the impact of alien species.

Ecohydrology: processes, models and case studies: an approach to the sustainable management of water resources

This book contains 15 chapters dealing with the integration of ecology with hydrology at the rive... more This book contains 15 chapters dealing with the integration of ecology with hydrology at the river basin scale. The patterns and processes in the catchment including nutrients, lotic vegetation ...

Macdonald/Key Topics in Conservation Biology 2, 2013

Tropical Stream Ecology, 2008

... The retention of a low metabolic rate, which is a primitive evolutionary trait that ... III. ... more ... The retention of a low metabolic rate, which is a primitive evolutionary trait that ... III. REPTILES The early origin and the apparently &amp;#x27;primitive&amp;#x27;character of reptiles contrast with their ... the agamid waterdragons Physignathus cocincinus (Green or Chinese water dragon), P. lesueurii ...

Freshwater Biology, 2011

... FRANCESCA GHERARDI*, KENNETH M. MAVUTI, NIC PACINI, ELENA TRICARICO* ANDDAVID M. HARPER§ *D... more ... FRANCESCA GHERARDI*, KENNETH M. MAVUTI, NIC PACINI, ELENA TRICARICO* ANDDAVID M. HARPER§ *Dipartimento di Biologia Evoluzionistica &#x27;Leo Pardi ... Britton et al., 2007), the African Tilapia zillii (Gervais) (order: Perciformes; family: Cichlidae) (Muchiri, Hart &amp; ...

... 2002)(Figure 2). 48 29/2010 Field IT for East Africa: training young African scientists in ... more ... 2002)(Figure 2). 48 29/2010 Field IT for East Africa: training young African scientists in Lake Naivasha (Kenya) David M. Harper ... two tilapias (Ore-ochromis leucostictus and Tilapia zillii), which had survived following a number of re-introductions through the 1950s (Muchiri et al. ...

Diversity, 2021

Resource partitioning, the division of limited resources by species to help avoid competition, ha... more Resource partitioning, the division of limited resources by species to help avoid competition, has been observed in freshwater turtle assemblages in several natural systems but has rarely been studied in tropical African ecosystems. Here, we investigate habitat preferences of two congeneric species in the family Pelomedusidae, Pelusios castaneus and P. cupulatta, in riverine/wetland habitats in the southern Ivory Coast (West Africa). Pelusios castaneus is a widespread species across West-central African savannahs and open forests, whereas P. cupulatta is endemic to the Upper Guinean forest region in West Africa. The two species have a similar diet composition (mainly carnivorous) but diverge considerably in body size, P. cupulatta being much larger. We use hand-fishing-nets and fishing funnel traps to record turtles in 18 distinct sites and analyze habitat preferences by species at two spatial scales. At a macro-habitat scale, P. castaneus is captured mainly in marshlands, whereas P...

Wetlands Ecology and Management, 2014

Recent innovations in the briquetting of carbonized biomass have the potential to improve the eff... more Recent innovations in the briquetting of carbonized biomass have the potential to improve the efficacy of papyrus as a fuel source. Selective harvesting of only mature stems may prove more sustainable than experimental clear-cutting approaches to regeneration pursued in earlier studies, whilst still providing up to 90 % of available biomass. Briquettes produced from papyrus compare favourably with alternative local fuels, both in physical properties and from the perspectives of potential end-users. Papyrus wetlands at Lake Naivasha, Kenya, may have the potential to provide 1.5 9 10 9 cuboid briquettes (volume c. 90 cm 3 ; weight c. 25 g) from a biannual harvest, satisfying the domestic fuel requirements of[ 85 % of the District's population whilst simultaneously reducing pressure on forests exploited for the production of wood charcoal.