Migratory behaviour of a dominant detritivorous fish Prochilodus lineatus evaluated by multivariate biochemical and pollutant data

Abstract

This paper studies the migration pathways and ranges of a dominant detritivorous fish Prochilodus lineatus along pollution gradients in the Río de la Plata basin using multivariate analysis of biochemical and pollutant data. Biochemical composition (water, ash, lipids, proteins, carbohydrates, neutral lipids classes and fatty acids), aliphatic hydrocarbons (ALI), polychlorinated biphenyls (PCB), linear alkylbenzenes (LAB) and organochlorine pesticides (OClP) were determined in muscle samples of P. lineatus collected in Metropolitan Buenos Aires, the lower Paraná River (Paraná: 200-1000 km from Buenos Aires) and the middle Paraná and Paraguay Rivers (North: 1000-1400 km north). Biochemical variables and pollutants exhibited large variability [Lipids 1.1-89.5% wet mass; ALI 1.4-413; LABs not detectable (n.d.)-115.2; PCBs n.d.-27.9; OClPs n.d.-11.8 µg g(-1) dry mass], due to the contrast of Buenos Aires with North fish. Fish from Buenos Aires were fatty (lipids 24.7 ± 12.3% wet mass), enriched in 18 carbon fatty acids and severely contaminated (ALI 152.4 ± 72.3; LABs 65.1 ± 26.4; PCBs 15.2 ± 6.8; OClPs 1.8 ± 1.9 µg g(-1) dry mass mean ±S.D.). In contrast, fish from North were lean (4.1 ± 3.1% wet mass), enriched in long chain (>20 carbons) polyunsaturated fatty acids, with average one to two orders of magnitude lower pollutant levels (ALI 41.2 ± 51.9; PCBs 2.2 ± 3.5; LABs 8.8 ± 21.1; OClPs 0.67 ± 0.75 µg g(-1) dry mass mean ±S.D.). Paraná showed intermediate values in all variables, denoting the mixing of different fish stocks. Based on principal component analysis, 14 outliers from 60 North and Paraná samples (representing 26 from 108 individual fish) were identified as pertaining to the Buenos Aires group with very similar lipid and pollutant levels. Data suggest that P. lineatus migrates a highly variable distance, exceeding 800-1000 km in multiple spatial and temporal overlapping ranges. Chemometric analysis of biochemical and pollutant data effectively discriminates fish according to the chemical signature acquired by detritus feeding in pristine and contaminated urban or industrial areas.

Fatty acid alterations in the detritivorous Prochilodus lineatus promoted by opportunistic feeding on sewage discharges in the Río de la Plata estuary

“…Similarly, fatty acid composition of Buenos Aires P. lineatus was significantly enriched in 18C‐FA (Tukey HSD, P < 0·001), especially 18:1n‐9 and 18:2n‐6, and had lower proportions of 16:1n‐7 and LC‐PUFA (Tukey HSD, P < 0·001), especially 20:4n‐6, 20:5 and 22:6n‐3. A group of 15 Mid‐Paraná individuals (BA MIG) identified as migratory P. lineatus from Buenos Aires based on their length–mass relationship, biochemical composition and pollutant fingerprint (Speranza et al ., ) presented similar lipid, contaminant contents and fatty acid profiles to Buenos Aires P. lineatus [Tables and SI (Supporting Information)]. Excluding these P. lineatus from Mid‐Paraná, the fatty acid composition became indistinguishable from North P. lineatus (18C‐FA: 38·8 ± 7·9%, LC‐PUFA: 16·0 ± 4·7%).…”

Migration and brackish environment use of Prochilodus lineatus (Characiformes: Prochilodontidae) inferred by Sr:Ca ratio transects of otolith

“…Other methodologies have been used to study migratory and biological aspects of the streaked prochilod, primarily tagging and recapture (Bonetto et al, 1981;Delfino, Baigun, 1985;Sverlij et al, 1993;Espinach Ros et al, 1998) although biochemical methods (Colombo et al, 2011;Speranza et al, 2012) and distribution studies (Bayley, 1973;Stassen et al, 2012) have also been conducted. These studies show brackish use in some specimens, but also suggested the presence of non-migratory fish, especially in the Uruguay River (Bonetto et al, 1981;Delfino, Baigun, 1985;Espinach Ros et al, 1998).…”

“…Considering the use of brackish waters and migration distances, other methods of assessment and management should be considered in order to ensure not only the sustainability of the fishery but also the quality of the product for consumption. Management methods should consider connectivity between different points in the basin, paying special attention to brackish use by the species, since this could affect the quality of the meat and affect consumer health (Colombo et al, 2011;Speranza et al, 2012).…”

Geographic distribution of the short-tailed river stingray (Potamotrygon brachyura): assessing habitat loss and fishing as threats to the world’s largest obligate freshwater elasmobranch

“…Coastal areas of the RdlP, especially the southern (Argentinian) shore, are among the most modified and polluted in the basin because this area contains large industrialised urban conglomerates (Murguía et al 2006;Barletta et al 2010). For example, the concentration of hydrocarbon and polychlorinated biphenyls in detritivorous fish from the southern shore of the RdlP was 1-2 orders of magnitude higher than that of fish from the lower Paraguay River (Speranza et al 2012). Access to the main ports in the RdlP is maintained through dredging, which destroys the physical structure of the benthic ecosystem.…”