4 research outputs found
THREATENED FISHES OF THE WORLD: Coptodon walteri (Thys van den Audenaerde 1968) (Perciformes: Cichlidae)
Coptodon walteri, Thys van den Audenaerde, 1968, je endemski ciklid iz Obale Bjelokosti i Liberije koji je ocijenjen kao gotovo ugrožena vrsta zbog ribolovnog pritiska, gubitka staniÅ”ta i zagaÄenja vode zbog opsežnog iskapanja zlata u koritu rijeke Cavally. Iskazana je izrazita potreba za izradom planova zaÅ”tite i upravljanja za ovu vrstu.Coptodon walteri Thys van den Audenaerde 1968, an endemic cichlid of Ivory Coast and Liberia, is assessed as Near Threatened due to fishing pressure, and loss of habitats and aquatic pollution as a result of extensive clandestine gold mining in the bed of the Cavally River. There is an immediate need for developing conservation and management plans for this species
Genetic Adaptability of Sarotherodon Melanotheron to Polycyclic Aromatic Hydrocarbons (PAHs) in Some Senegal Hydrosystems
The objective of this study is to evaluate the level of Polycyclic Aromatic Hydrocarbons (PAH) contamination at the Sine-Saloum (Foundiougne, Kaolack and Missirah), Hann Bay and Niayes (1 and 2) sites in SƩnƩgal and genetic ecotoxicology of Sarotherodon melanotheron specimens from these sites.The genes of the specimens were studied by the enzymatic electrophoresis technique. Seven enzymatic systems (ADH, AAT, IDHP, MDH, PGM, GPI and EST) were analyzed. The analysis of the PAHs was carried out by gas chromatography coupled to mass spectrometry (GCMS). Populations of Sarotherodon melanotheron and sediments used for PAH measurements were sampled in 2009. Chemical characterization of the sampling sites revealed a high concentration of PAHs at Foundiougne and Hann Bay. The high pollution of environment is characterized by PAH napht (Foundiougne (14 378 ng/g) ; Hann Bay (5856 ng/g). The analysis of allelic variability showed the existence of an adaptive polymorphism at the PGM locus in S. melanotheron. The particularly low frequencies of the PGM * 105 allele in populations of disturbed environment (Foundiougne, Kaolack, Hann Bay, Niayes 1 and Niayes 2) suggest its involvement in the response to environmental stress. A negative correlation was observed between the PGM, IDHP and MDH-1 locus and PAH. The presence of PAHs in the environmentcauses to a decrease in the frequency of the PGM * 105 alleleatS. melanotheronspecimens
PREDVIÄANJE ÄIMBENIKA KOJI UTJEÄU NA SASTAV STRUKTURA RIBA U ÄETIRI OBALNE RIJEKE (JUGOISTOÄNA OBALA BJELOKOSTI) POMOÄU UMJETNIH NEURONSKIH MREŽA
The present study is focused on small coastal rivers in southeast Ivory
Coast, aimed to predict species richness of fish guilds and to test contribution
of environmental variables for explaining guild structure with Self-
Organizing Map (SOM) and Backpropagation (BP) algorithms. The former
method was applied to pattern the samples based on the richness of six
major fish guilds observed (benthivores, invertivores, detritivores, piscivores,
herbivores and omnivores). Four clusters were identified: cluster I
was characterised by benthivores, cluster II was distinguished by invertivores,
detritivores, piscivores and omnivores, cluster III had high richness of
benthivores, invertivores and herbivores, and cluster IV had high numbers
of omnivore, detritivore and piscivore species. The BP showed high predictability
(0.89 for benthivores, 0.85 for omnivores and Odonata, 0.84 for
herbivores). There was high correlation between observed and estimated
values for piscivores (0.77) and detritivores (0.72); the poorest fit was for
invertivores (0.63). The frequency histogram of residuals showed that most
residuals lie around zero for all guilds. The most contributing variables in
predicting the six fish trophic guilds were water temperature, conductivity,
total dissolved solids, dissolved oxygen, depth, width, canopy and distance
from source. This underlines the crucial influence of both instream characteristics
and riparian environment.Ovo je istraživanje usmjereno prema malim obalnim rijekama
na jugoistoÄnoj Obali Bjelokosti s ciljem predviÄanja bogatstva
vrsta riba i testiranjem doprinosa varijabli iz okolice
kako bi se objasnila struktura populacija pomoÄu samoorganiziranih
karata (SOM) i povratnih (BP) algoritama. Metoda
je primijenjena na uzorku temeljenim na bogatstvu Ŕest glavnih
zabilježenih tipova ishrane (bentivori, invertivori, detrivori,
piscivori, herbivori i omnivori). Identificirane su Äetiri skupine:
klaster I je karakteriziran bentivorima, klaster II se odlikuje
invertivorima, detrivorima, piscivorima i omnivorima,
klaster III je bogat bentivorima, invertivorima i herbivorima, a
klaster IV je imao visok broj omnivora, detrivora i piscivora.
BP je pokazao visoku predvidljivost (0,89 za bentivore, 0,85
za omnivore i Odonata, 0,84 za herbivore). Visoka korelacija
je zamijeÄena izmeÄu promatranih i procijenjenih vrijednosti za piscivore (0,77) i detrivore (0,72), a najmanja za invertivore
(0,63). Histogram pokazuje da se veÄina ostataka kreÄe
oko nule za sve osobine. Varijable koje su najviŔe doprinijele
predviÄanju Å”est trofiÄkih ribljih struktura su temperatura
vode, provodljivost, ukupno otopljene tvari, otopljeni kisik,
dubina, Ŕirina, zasjenjenost i udaljenost od izvora. To naglaŔava
presudan utjecaj karakteristika vodotoka i priobalnog
okoliŔa
Threatened fishes of the world: Coptodon walteri (Thys van den Audenaerde 1968) (Perciformes: Cichlidae)
Coptodon walteri Thys van den Audenaerde 1968, an endemic cichlid of Ivory Coast and Liberia, is assessed as Near Threatened due to fishing pressure and loss of habitats, and aquatic pollution as a result of extensive clandestine gold mining in the bed of the Cavally River. There is an immediate need for developing conservation and management plans for this species