Anthropic Pressure Research Articles

Extinction of endemic taxa as a direct consequence of global climate change

Global climate change occurs from both natural and anthropic causes. Anthropic climate change has effects at various scales and occurs faster than the adaptation of species to these changes. Protected natural areas have been created to preserve species from the different threats facing them. Sierra La Laguna is a sky island with almost no anthropic pressure given its natural isolation; it is home to several endemic taxa, including Peromyscus truei lagunae and Sorex ornatus lagunae. This study aims to assess the possible impact of climate change on species endemic to a sky island exposed to virtually no local anthropic pressure. The Sierra La Laguna sky island, located in the southern region of the Baja California peninsula, harbors different vegetation types, including an oak-pine forest at the highest elevations and xeric vegetation at lower ones. Ecological niche models were developed under three climate change scenarios contemplating temperature rises of 1.5 °C and 4.4 °C. There are insufficient localities to make statistically robust models for mammalian species. Therefore, we used plant species typical of the oak-pine forest (Pinus cembroides lagunae, Quercus brandegeei, and Q. devia) and the rodents Peromyscus eva, that thrives in dry deciduous forests, and Chaetodipus rudinoris and C. spinatus, associated with xeric ecosystems. The models show that ecological suitability for the oak species decreases, while it is completely lost for the pine species. On the other hand, P. eva broadens its elevational range, while C. rudinoris and C. spinatus increase their ecological suitability in both area and elevation. The Sierra La Laguna sky island is an area with virtually no regional or local anthropic pressure. Nonetheless, the projections conducted under various climate change scenarios show a loss of up to 100 % of the area of climatic and elevational suitability for species characteristic of the oak-pine forest even with the minimum temperature rise of 1.5 °C. These results suggest that, under these conditions, endemic species such as P. t. lagunae and S. o. lagunae will become extinguished despite the absence of local anthropic pressures.

Pollution, risks, and sources of heavy metals in sediments from the urban rivers flowing into Haizhou Bay, China.

The Haizhou Bay in eastern China, for a long time, is seriously polluted with heavy metals (HMs) due to intensive anthropic pressure. The river runoff is the dominant pathway of HM transport in the coastal region. However, the information on HM pollution in coastal rivers flowing into Haizhou Bay was still limited, and potential risks and possible sources raised by HMs in this area were neglected up to now. To fully understand the distribution and ecological risks of sediments in seven rivers along the bay, surface sediments were collected and seven HMs (Cr, Mn, Ni, Cu, Zn, Cd, and Pb) were investigated. The results showed that HM concentrations generally met the primary standard criteria of China (marine sediment quality), except for Cu and Zn. On the other hand, Zn and Cu tended to exhibit probable adverse biological effects in the Shawang River comparison with some sediment quality guidelines (SQGs). Moreover, the enrichment factor and geo-accumulation index demonstrated that there was no or slight contamination to be found for Cr, Mn, Ni, Cu, Zn, and Pb and moderate pollution for Cd. The contamination factor (Cfi), integrated contamination degree (CF), modified degree of contamination (mCd), and modified pollution index (MPI) revealed individual metal contamination in localized areas. In these river sediments, the potential ecological risk (RI) was low to moderate, except Cd posted a considerable ecological risk because of its high enrichment. Furthermore, the Shawang River and Linhong River were seriously polluted with HMs among seven rivers. These results provided a new direction for controlling HM pollution in Haizhou Bay which suggested substantial measures should be implemented to alleviate the potential risk of HMs, to these rivers sediments.

EDNA profiling of mammals, birds, and fish of surface waters by mitochondrial metagenomics: application for source tracking of fecal contamination in surface waters.

Knowing the composition of animals present in aquatic ecosystems can tell us about the anthropic pressures on these environments. One of these pressures is the occurrence of fecal contamination. However, this contamination can originate from more than one animal species in areas where urban and agricultural activities overlap. Mitochondrial DNA (mtDNA) has become the standard barcoding tool to identify the presence of animal species in environment. Amplicon-sequencing metagenomics is a powerful approach to derive the animal profile in an environment. However, PCR primers targeting mtDNA of a broad range of animals are highly degenerate or generate short DNA fragments that could cause ambiguous affiliation. Here we report the development of a new set of primers targeting the mitochondrial 16S ribosomal RNA genes of a broad range of terrestrial and aquatic animals, which include mammals, birds, and fishes. These primers successfully amplified mtDNA from environmental DNA (eDNA) extracted from surface waters. Sequencing the resulting amplicons revealed the presence of mammals and birds that may contribute in fecal contamination of surface water. In one of the river samples high in fecal indicator bacteria, human and bovine mtDNA accounted for 40.5% and 4.1% of the sequences, respectively, suggesting fecal contamination by these two animals. These findings indicate that our PCR primers coupled with amplicon-sequencing metagenomics contribute in profiling the animal diversity in the surface waters and its surrounding. This approach could be a valuable tool to identify simultaneously the potential contribution of various animals as sources of fecal contamination in surface waters.

Resistance Patterns, mcr-4 and OXA-48 Genes, and Virulence Factors of Escherichia coli from Apennine Chamois Living in Sympatry with Domestic Species, Italy.

Simple SummaryAntimicrobial resistance is a global threat involving human, animal, and environmental health. Evidence of antibiotic resistance was found in pets, livestock, humans, in uncontaminated environments, or in animals never treated with antibiotics. In order to provide new data, this study was carried out in the protected area of the Maiella National Park (Central Italy) sampling wild and domestic ungulates that share or do not share grazing lands. The analysis was realized by combining the georeferenced data of animals and the microbiological investigations starting from fresh fecal samples. The Escherichia coli isolates were tested for antibiotics particularly relevant in human health. Even if the selected molecules are not currently used in veterinary medicine, evidence of resistant bacteria was found in sympatric wild and domestic animals, as well as in non-sympatric domestic animals. The detection of colistin resistance gene mcr-4 and carbapenems resistance genes OXA-48 was reported for the first time in wild ungulates in Italy and in Europe. More investigations are necessary, but these preliminary results highlight the importance of continuing studies for the early detection of emerging resistance patterns.The aim of this study was to determine and characterize potential resistance mechanisms against selected Critically Important Antibiotics in Escherichia coli isolates collected from wild and domestic ruminants living in the Maiella National Park, in Central Italy. A total of 38 isolates were obtained from red deer, Apennine chamois, cattle, sheep, and goats grazing in lands with different levels of anthropic pressure. Antimicrobial susceptibility was determined by Minimal Inhibitory Concentration testing, showing phenotypic resistance to colistin, meropenem, or ceftazidime in 9 isolates along with one bacterial strain being resistant to three of the tested antibiotics. In addition, the biomolecular assays allowed the amplification of the genes conferring the colistin (mcr-4), the carbapenems (OXA-48), penicillins and cephalosporins (TEM, SHV, CMY-1, CMY-2) resistance. In order to describe the potential pathogenicity of isolates under study, virulence genes related to Shiga toxin-producing (STEC) and enteropathogenic (EPEC) pathovars were identified. This study is the first report of mcr-4 and OXA-48 genes in resistant E. coli harboring virulence genes in Italian wildlife, with special regard to Apennine chamois and red deer species. The multidisciplinary approach used in this study can improve the early detection of emerging antibiotic resistance determinants in human-animal-environment interfaces by means of wildlife monitoring.

Habitat use of common dolphin (Delphinus sp.) in the Mochima National Park, Sucre, Venezuela.

In Venezuela, common dolphin (Delphinus sp.) is considered the cetacean with the highest incidence. Studies in the region indicate a possible isolated coastal population so called Venezuelan stock settled mainly in the northeast of the country. . The objective of this study is to describe the habitat use of common dolphin in the Mochima National Park (MNP), a protected area with a high and growing anthropic pressure. Seventy surveys were carried out, with predefined survey route, from September 2009 to August 2010. Each group sighted was monitored while possible to a maximum of 30min.. During this time we registered location (Latitude-longitude), behaviour, group size and composition every 5min. Additionally, environmental variables were assessed from the sight location in a nautical chart. The study area was divided into a grid (cell: 500 x 500m) and the Coefficient of Area Use (CAU) was calculated for each cell. The proportion of the total observation time where the common dolphin displayed behaviours into the areas being used was estimated. A logistic regression model was applied to identify the variables that better explained usage pattern. In 55h of observation, 111 groups were recorded. The common dolphin used the habitat differentially, showing preferences for shallow areas near to the coast. Areas of greatest intensity of use were Tigrillo inlet and the northeast of the Caracas Islands. The probability of presence of dolphins decreased with depth and distance to the coast. Common dolphin invested more time in feeding and socializing activities. Behaviours were significantly dependent of season, group size, composition, depth and distance to the coast. Finally, these data on habitat use and behaviour allow the identification of priority habitats. Throughout the year, the MNP provided areas for refuge, feeding and resting. , It is therefore imperative to promote management and conservation policies that prevent the negative impacts of the increasing tourism and fishing activities we observed in this Park.

Tritium as a tool to assess leachate contamination: An example from Conversano landfill (Southern Italy)

This paper describes the geochemical and isotopic data processing combined with statistical analysis aimed to fine-tune the tritium background threshold limits to identify groundwater contamination due to leachate dispersion at a very high level of sensitivity. The selected case study refers to a landfill located in area subjected to marine intrusion and intense anthropic pressure due to agricultural activities. The investigated aquifer pertains to a karst system with a geological structure that potentially allows an easy spread of contamination. Twenty wells, with depth ranging from 179 to 462 m, and 4 leachate samples, were collected and analysed for main dissolved ions, some minor and trace species (NH4+, NO2−, Br−) and isotope content (δ18O, δ2H and tritium). The adopted approach allowed defining the geochemical background of groundwater tritium content, and confirming that tritium content is an effective leachate tracer, both for the high contrast between groundwater and leachate, and for its conservative characteristics. These characteristics make tritium the leachate tracer par excellence, far preferable to any chemical or other isotopic parameters, whose variations may be influenced by chemical and physical processes other than leachate contamination.

Satellite–Derived Topography and Morphometry for VHR Coastal Habitat Mapping: The Pleiades–1 Tri–Stereo Enhancement

The evolution of the coastal fringe is closely linked to the impact of climate change, specifically increases in sea level and storm intensity. The anthropic pressure that is inflicted on these fragile environments strengthens the risk. Therefore, numerous research projects look into the possibility of monitoring and understanding the coastal environment in order to better identify its dynamics and adaptation to the major changes that are currently taking place in the landscape. This new study aims to improve the habitat mapping/classification at Very High Resolution (VHR) using Pleiades–1–derived topography, its morphometric by–products, and Pleiades–1–derived imageries. A tri–stereo dataset was acquired and processed by image pairing to obtain nine digital surface models (DSM) that were 0.50 m pixel size using the free software RSP (RPC Stereo Processor) and that were calibrated and validated with the 2018–LiDAR dataset that was available for the study area: the Emerald Coast in Brittany (France). Four morphometric predictors that were derived from the best of the nine generated DSMs were calculated via a freely available software (SAGA GIS): slope, aspect, topographic position index (TPI), and TPI–based landform classification (TPILC). A maximum likelihood classification of the area was calculated using nine classes: the salt marsh, dune, rock, urban, field, forest, beach, road, and seawater classes. With an RMSE of 4 m, the DSM#2–3_1 (from images #2 and #3 with one ground control point) outperformed the other DSMs. The classification results that were computed from the DSM#2–3_1 demonstrate the importance of the contribution of the morphometric predictors that were added to the reference Red–Green–Blue (RGB, 76.37% in overall accuracy, OA). The best combination of TPILC that was added to the RGB + DSM provided a gain of 13% in the OA, reaching 89.37%. These findings will help scientists and managers who are tasked with coastal risks at VHR.

Influence of different types of margins in the fish assemblage from an urban river

The presence or absence of a fish species may be associated with the physical and chemical characteristics of the water, in addition to the state of preservation of the riparian zone. This study examined whether the taxonomic fish composition in an urban river varies along three riparian zone preservation conditions: preserved, intermediate preservation and degraded. Six urban stretches of the Sorocaba/São Paulo River were selected for this study, with monthly sampling being carried out from June 2019 to February 2020. The samplings were carried out with the aid of a sieve, dip net, and trawl. Regarding the types of margins and environmental variables, the Principal Component Analysis explained 97.49% of the data variation, axis 1, which explained 91.85% of the total variation, was formed by the variables conductivity and total dissolved solids. Axis 2, which explained 5.64% of the variation, was formed by Sun Rays% and Siltation%, being inversely proportional to Riparian Forest%. For the ichthyofauna, the samples consisted in 50,983 fish distributed in 5 orders, 8 families, and 12 species. Cyprinodontiformes had the highest abundance, with 96.96% of the total number of individuals, followed by Siluriformes (2.39%), and the sum of the other orders did not reach 1% of the total collected. According to each type of margin, it was possible to register 11,592 individuals for the Margin A – preserved, with S=8 species, being 2 exclusive (Corydoras flaveolus and Hoplosternum littorale) and 3 exotic (Coptodon rendalli, Pterygoplichthys ambrosettii, and Poecilia reticulata), the latter was dominant in all types of margins. For Margin B – intermediate preservation, 19,645 individuals were sampled, with S=5 species, no exclusive species, only exotic and more tolerant native species such as Hoplias malabaricus and Hypostomus ancistroides. For Margin C – degraded, 19,746 individuals were recorded, the largest number of species (S=10), 3 were exclusive to this type of margin (Psalidodon fasciatus, Rhamdia Quelen, and Geophagus brasiliensis). The pairwise comparison (similarity percentage) showed that the assemblage structure was different for the types of margins. The Canonical Correspondence Analysis explained 92.46% of the total data variation, showing the relationship of species to environmental data. It is evident the importance of preservation of micro-habitats still present in the locals sampled, since different anthropic pressures cause great loss of diversity, especially for native and more sensitive species.

Fish biodiversity of a tropical estuary under severe anthropic pressure (Doce River, Brazil)

Abstract The Doce River has undergone severe changes over the last centuries (e.g., flow regulation, pollution, habitat and species loss). Here, we present the first comprehensive fish biodiversity assessment of the Doce River estuary and a summary of the main impacts and their drivers for the whole river since the early 18th century. Carangiformes, Siluriformes and Eupercaria incertae sedis were the most representative orders for the 115 species recorded. Most species are native (87.8%), euryhaline/peripheral (80%) and zoobenthivorous (33.9%). Threatened (Paragenidens grandoculis, Genidens barbus, and Lutjanus cyanopterus) and near threatened (Cynoscion acoupa, Dormitator maculatus, Lutjanus jocu, Lutjanus synagris, and Mugil liza) species are peripheral. Thirteen species are exotic at the country (Butis koilomatodon, Coptodon rendalli, and Oreochromis niloticus) or the basin level (e.g., Pygocentrus nattereri and Salminus brasiliensis). The catfish Cathorops cf. arenatus is reported for the first time on the eastern coast of Brazil and Paragenidens grandoculis, considered extinct in the Doce River, was discovered in the estuary.

Three centuries of dynamics in the lowland section, induced by human impact: A sociogeomorphic approach

This study aims to analyze one of the most dynamic sections in the lower part of the Mureș River, Lipova-Arad sector. The geological and tectonic context influenced the shifts of the watercourse at both a regional scale and a local one. The channelization works have shortened the length of the channel by 1/3 of it. The flood events in the 70s and the mining activity have also influenced the evolution of the river in last decades. Accelerating the geomorphological processes, mostly after the great floods, have narrowed the channel by 35%, and have reduced the total islands surface by almost 80%. In this context, the Mureș River try to reach the dynamic equilibrium state had before the human interventions. Under the anthropic pressure the geomorphological processes have been accelerated and the landscape left behind in Lipova-Arad section, along the Mureș River suffered important changes.

Novidades do estrato herbáceo em uma região chave para a conservação da Amazônia Meridional

Abstract The contribution of the herbaceous stratum to tropical plant diversity is considerable, however this component remains undersampled. We investigated floristic, structural, ecological and conservation issues concerning the herbaceous component of a seasonal deciduous forest associated with granitic rock outcrops in the Cristalino Region, a key area for biodiversity conservation in the Brazilian Amazon. We installed a permanent plot of 1 ha, allocating 10 transect-lines of 20 m each. We identified the sampled individuals, measured height and projection, and verified cover and frequency per species, genera and family. We recorded 86 species, 62 genera and 25 families, with Orchidaceae being the family with the highest species richness. Among the 26 new species added to Cristalino Flora, we included Philodendron deflexum Poepp. ex Schott and Griffinia nocturna Ravenna, the latter ‘Critically Endangered’. Furthermore, the occurrence of G. nocturna in an Amazonian forest matrix is a novelty in this study. The estimate of species diversity according to Shannon-Wiener (H’) was 2.43 nats.ind.-1 (equivalent to 11.37 ± 0.90 IC95% equally common species), and according to Simpson (1/D), 6.82 (± 0.648 IC95%). The rarefaction and extrapolation curves for the diversity estimates tended to stabilize. Although the vegetation on rock outcrops usually presents a high number of endemic species, this pattern was not found in our study area, which can be explained by its continuous occurrence in the forest matrix. The understory of our study area consists in a mixture of floras, being composed mainly of species from the Amazon and/or Cerrado biomes. In view of the current anthropic pressure faced by the southern Amazon, we reinforce the importance of carrying out inventories of its herbaceous communities, since the risk of species loss is even more alarming when considering present undersampling of this component.

The flora of pine forests of the vicinity of Hrafske village (Vovchansk District, Kharkiv Region)

The article presents the results of a study of the flora of pine forests in the vicinities of the villages Hrafske, Verkhnia Pysarivka, and Symonivka of the Vovchansk District of the Kharkiv Region. The flora of the investigated area includes at least 120 species of vascular plants of 47 families, five classes, and four divisions. The richest in the flora are the families Asteraceae (22 species; 18.3%), Poaceae (13 species; 10.8%), and Caryophyllaceae (10 species; 8.3%) that are characteristic of the pine forests of the Kharkiv Region. The presence of Crassulaceae (5 species; 4.2%) at the fifth position in the spectrum of dominating families is due to anthropogenic impact on the vegetation of the study area. Analysis of the flora ecological structure by three main abiotic factors (soil water regime, total salt regime, and light) has shown the typical conditions of the valley forests of the Kharkiv Region with a predominance of mesophytic and submesophytic (84 species; 70%), semieutrophic (64 species; 52.9%) and subheliophytic (88 species; 72.7%) groups of plants. In the coenotic structure of the flora of studied forests, the forest (38 species; 31.4%) and ruderal (37 species; 30.6%) fractions were the leading ones, while the third position was occupied by the psammophytic species (22; 18.2%). A high number of weeds in the flora composition is explained by urbanization. Fractional analysis of the flora has shown a predominance of native species (90; 75%), mainly apophytes (47; 39.2%), adapted to growing in disturbed habitats. The adventive fraction includes 30 species (25%), among which kenophytes and xenophytes predominate. Localities of three rare species (Dryopteris carthusiana (Vill.) H.P. Fuch, Jurinea charkoviensis Klok., and Viburnum opulus (L.) Opiz.) were identified, which indicated conservation value of the study area. An index of the flora synanthropization (64.5%) is quite high due to ruderal species adapted to disturbed habitats. The studied valley forests are under anthropic pressure caused by nearby settlements via littering and deforestation, which results in flora impoverishment and the spread of alien plant species. Therefore, the forests in question require further monitoring.

Geodiversity, Geoconservation, and Geotourism in Central America

Central America is located in a dynamic region where tectonics and volcanism together with the tropical climate and its diverse vegetation have shaped the landscapes. Our main objective is to review the status of the geodiversity, geoconservation, and geotourism in Central America. We will identify the region’s geomorphic environments and geodiversity using classic regional geomorphology mapping techniques. Likewise, using touristic maps and webpages, we identify the most prominent geosites of different origin in Central America. Moreover, we will explore the national environmental policies, natural conservation systems, and tourism initiatives to promote their national geoheritage through geotourism. We found that volcanic, coastal, karstic, glacial, and fluvial geomorphic environments are the most common in the region. In addition, we identified 393 geosites of volcanic, coastal, karstic, glacial, fluvial, and archeological origin in Central America. The promotion of geoheritage, geodiversity, geoconservation, and thus the development of geoparks are excellent opportunities to promote sustainable development, sustainable lifestyles, appreciation of natural and cultural diversity, and the promotion of peace. These results may prove important to spread information about geoscience widely to decision makers on geotourism and conservation in each country and the stakeholders of the region. Geoheritage studies in tropical and developing countries such as those in Central America should be improved, and priority should be given to the geomorphological dynamics and strong anthropic pressures on their geo- and biodiversity to increase their income through geotourism, especially among the less favored communities and avoid affecting their already threatened natural resources.

Biogeochemical responses of a highly polluted tropical coastal lagoon after the passage of a strong hurricane (Hurricane Irma)

Abstract Laguna Larga (Cayo Coco, Cuba) is a eutrophic coastal lagoon due to tourism development. As part of long-term monitoring of Laguna Larga, we were able to follow the lagoon's water quality from 2015 to 2018 and could assess the impacts of Hurricane Irma (September 8–9, 2017) by intensifying our sampling frequency. Physicochemical parameters (salinity, pH, dissolved oxygen, dissolved inorganic nitrogen, dissolved reactive silicate and total nitrogen) exhibited significant variations associated with Hurricane Irma. Salinity decreased due to the extraordinary rainfall of the hurricane (339.8 mm/24 h, a new record for Cayo Coco). The water level in the lagoon rose 0.85 m. Strong hurricane winds and intense runoff drove organic matter and sediment resuspension. Anoxia and an increase of nutrients occurred throughout the lagoon. The main biogeochemical impact was that it boosted these eutrophic conditions of the lagoon, to levels that lasted for several months. A significant correlation among nutrients, salinity and dissolved oxygen was found. After 6 months, water quality in the lagoon had recovered to conditions similar to those before the hurricane. The case of Laguna Larga shows that those coastal systems under anthropic pressure can take longer to recover after extreme climatic events, and highlights the need for long-term monitoring of tropical coastal ecosystems.

TERRESTRIAL VERTEBRATE FAUNA OF ASSIS’ STATE FOREST: A CERRADO REMNANT IN THE STATE OF SÃO PAULO, BRAZIL

In the current scenario of environmental changes, anthropic pressures on biodiversity are in constant increase, stressing the importance of assessing the distribution and occurrence of organisms in natural regions, especially in protected areas. Here we surveyed the terrestrial vertebrate fauna of Assis State Forest and updated the existing species list. Reptiles were sampled using pitfall traps and active search, birds by transects and listening points, while terrestrial mammals were sampled using camera traps, linear transect census, active search, pitfall and live traps. Four samplings were conducted, totaling 28 days of sampling effort. We recorded a total richness of 230 terrestrial vertebrate species: 21 amphibians, 17 reptiles, 164 birds, 23 medium and large-sized mammals and 25 small mammals. Of these, seven species are considered endangered at the state and / or federal level. Our results led to the inclusion of 78 bird species and six medium- and large-sized mammals to the species list of ASF’s Management Plan, in addition to three new species of herpetofauna that were not reported by other fauna surveys carried out in the region. Our data shows that the area is highly diverse, with some differences in species composition between sampled phytophysiognomies. These data can also be used to update the management plan for the area, as well as for the zoning of the unit.

Ecological Networks and Fluvial Corridors in Calabria (Southern Italy)

The anthropic pressure on natural systems is the main cause for the present process of biodiversity loss in terrestrial biosphere [1]. Really, the human disturbance on Earth affects the 74.1% of terrestrial and marine habitats, including 22.4% completely modified, 51.7% partially disturbed and just the 25.9% in natural and pristine conditions [2]. At the beginning of third millenium, in the middle of a post-industrial era, named “Anthropocene” [3], mankind is causing the greatest mass extinction of wildlife in terrestrial biosphere [4-6].

Status and perspectives of mangrove management in Côte d'Ivoire

Mangroves are ecosystems characteristic of intertidal zones in tropical and subtropical regions. Rhizophora racemosa, Avicennia germinans and Conocarpus erectus are characteristic mangrove species found in Côte d'Ivoire. These mangroves could disappear without being fully studied due to the strong anthropic pressure. This study therefore proposes to establish a detailed cartography of the mangroves reported in Côte d'Ivoire and to model their potential distribution. Mangroves cover approximately 57.92 km², ie a linear coverage of 20.11% of the 540.14 km of coastline. The extent of these mangroves also decreased by 4.91 km² between 1996 and 2016. The maximum entropy model presents low-altitude coastal areas with high rainfall as well as average sunshine as favorable to mangroves. The particular ecological characteristic of mangroves as well as their particular mode of operation deserve to be taken into account in studies of flora in Côte d'Ivoire. It is therefore opportune to consider larger studies focusing specifically on the mangroves present in Ivory.

Endogenous catch per unit effort and congestion externalities between vessels in a search‐matching model: Evidence from the French Guiana shrimp fishery

AbstractThis paper aims at explaining the recent rise in profits in the French Guiana shrimp fishery (FGSF) despite the overall fall in activity observed between 1990 and 2009. We develop a stochastic search‐matching version of the usual Cobb–Douglas bioeconomic fishery model. In this version catch per unit effort becomes endogenous, decreasing in the ratio of empty vessels to escaped fish, which we call “anthropic pressure” and which is determined by standard profit maximization. We first estimate the stochastic harvest function, which exhibits nearly constant returns to scale. We then show that a decrease in equilibrium anthropic pressure and congestion between vessels may be more than compensated by the consecutive rise in catch per unit effort. This leads to a fall in average harvesting costs and thus, to a rise in profits. In addition, we identify the condition under which a search‐matching fishery, working under open access, could reach a maximum economic yield equilibrium, which corresponds to a very particular case. Finally, the model makes it possible to evaluate the actual catch per unit effort and explain how the FGSF changed over the period considered with the help of the open access and maximum economic yield frameworks.

Temporal and Spatial Variations of Geodia cydonium (Jameson) (Porifera, Demospongiae) in the Mediterranean Confined Environments

Confined marine environments are particularly susceptible to climate change and anthropic pressures. Indeed, the long-term monitoring of benthic assemblages in these environments allows us to understand the direction of changes over time. The demosponge Geodia cydonium is a suitable study case, since it is widely represented in many Mediterranean environments, while being a long-living and important habitat-forming species. Here, we report the results of a descriptive study on temporal and spatial variations of this demosponge in three semi-enclosed environments along the Italian coast: Marsala Lagoon, Porto Cesareo Bay, and Mar Piccolo of Taranto. At Marsala and Porto Cesareo, the study compares the present data with those reported by the literature at the end of the 1990s. Caused by the modification of its preferential habitats, the data indicated the loss and a remarkable regression of this species at Porto Cesareo and Marsala, respectively. In addition, we hypothesized that the increase in severe weather phenomena in the small Bay of Porto Cesareo recorded during the last 20 years may have had a marked impact on water mass, thus affecting the sponge assemblages. At Taranto, despite a remarkable environmental degradation, G. cydonium has appeared stable and persistent in the last 45 years, thus representing one of the richest and most well-preserved populations in the Mediterranean Sea.

Integrated Surface-Groundwater Modelling of Nitrate Concentration in Mediterranean Rivers, the Júcar River Basin District, Spain

High nutrient discharge from groundwater (GW) into surface water (SW) have multiple undesirable effects on river water quality. With the aim to estimate the impact of anthropic pressures and river–aquifer interactions on nitrate status in SW, this study integrates two hydrological simulation and water quality models. PATRICAL models SW–GW interactions and RREA models streamflow changes due to human activity. The models were applied to the Júcar River Basin District (RBD), where 33% of the aquifers have a concentration above 50 mg NO3−/L. As a result, there is a direct linear correlation between the nitrate concentration in rivers and aquifers (Júcar r2 = 0.9, and Turia r2 = 0.8), since in these Mediterranean basins, the main amount of river flows comes from groundwater discharge. The concentration of nitrates in rivers and GW tends to increase downstream of the district, where artificial surfaces and agriculture are concentrated. The total NO3− load to Júcar RBD rivers was estimated at 10,202 tN/year (239 kg/km2/year), from which 99% is generated by diffuse pollution, and 3378 tN/year (79 kg/km2/year) is discharged into the Mediterranean Sea. Changes in nitrate concentration in the RBD rivers are strongly related to the source of irrigation water, river–aquifer interactions, and flow regulation. The models used in this paper allow the identification of pollution sources, the forecasting of nitrate concentration in surface and groundwater, and the evaluation of the efficiency of measures to prevent water degradation, among other applications.