Papers by Iván Loaiza Alamo
Science of the Total Environment, 2022
Scientific research addressing environmental conditions of aquatic ecosystems has high priority i... more Scientific research addressing environmental conditions of aquatic ecosystems has high priority in Peru. Nevertheless, there is a lack of knowledge on environmental contamination of Peruvian marine ecosystems. To address this knowledge gap, this review article summarizes the available information in order to estimate the environmental health status (EHS) of Peruvian marine ecosystems. In this study, none of the studied Peruvian marine ecosystems could be rated as EHS-good, and the southernmost locations showed the most degraded conditions and a low EHS. Freshwater and brackish ecosystems contribute to the overall metal concentrations in Peruvian marine ecosystems. Environmental contamination and stressors are also reaching the Peruvian Marine Protected Areas (MPAs). The management of coastal marine areas and MPAs in Peru should be urgently re-formulated. This study also identifies the optimal biomonitoring approach in the current economic situation in Peru, and how marine research studies can support adjacent fields, e.g. nutrition and human health.
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This study investigates the trophic interactions and As and Cd transfer along seven marine ecosys... more This study investigates the trophic interactions and As and Cd transfer along seven marine ecosystems in Peru. Five of these ecosystems are driven by aquaculture of the Peruvian scallop Argopecten purpuratus. A southward increased gradient of δ15N was observed among the three examined regions along the Peruvian coast. The stable isotope analysis in R (SIAR)-stable isotope mixing models helped to clarify the feeding ecology of A. purpuratus and its important predators (e.g., Bursa ventricosa, Romaleon setosum). The food items of A. purpuratus can be ranked in decreasing order of importance: seston > sediment > particulate organic matter (POM) > brackish-and-fresh water POM input, while A. purpuratus itself was found to be the main prey item for predators. The highest trophic magnification factors (TMFs) were 1.46 and 1.07 for As and Cd, respectively, and were both found at the location in front of the Illescas Reserve Zone (northern Peru). Metal biomagnification and non-biomagnification effects were found in the Peruvian marine food webs, but A. purpuratus always fitted the trophic metal magnification or bio-dilution regression model as intermediate consumer and/or prey. The TMFs and linear metal relationships implied that As contamination is a serious concern in marine ecosystems in Peru.
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Food Chemistry, 2020
Seafood could be a promising way to supplement healthy fatty acids and trace elements to the Peru... more Seafood could be a promising way to supplement healthy fatty acids and trace elements to the Peruvian diet. Seafood from northern Peru was characterized with the highest relative concentrations of long-chain polyunsaturated fatty acids (LC-PUFAs), while in the center region marine species had the lowest As and Pb contents. Peruvian marine species are rich in LC-PUFAs and micro-nutrients (Cu, Fe, Mn, Zn), including species considered as potentially edible (e.g. Cycloxanthops sexdecimdentatus), but also non-edible species (e.g. Caulerpa filiformis). Nevertheless, it is crucial to consider toxic metals, e.g. As and Cd, which could pose a risk for consumers. High levels of beneficial LC-PUFAs and micro-nutrients would be taken up (up to 80% of the recommended values) when the Peruvian population would consume the estimated safe amount of seafood. Scoring species for fatty acid and metal content resulted in gastropods (e.g. Bursa ventricosa) as being the least beneficial species.
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CHEMOSPHERE, 2019
The present study analyzed the Peruvian scallop Argopecten purpuratus and its food sources for me... more The present study analyzed the Peruvian scallop Argopecten purpuratus and its food sources for metal and fatty acid concentrations in order to determine spatial and temporal differences. Metals such as copper (Cu), manganese (Mn), and zinc (Zn) in gills and iron (Fe) and Zn in sediments were the most significant explaining factors for spatial differentiations (degree of contamination), while for fatty acids, it was C14:0, C15:0, C16:0 and C18:0 in A. purpuratus' muscle and in its food sources, which explained more temporal differences (El Niño-Southern Oscillation (ENSO) effect). Gills, digestive gland and intestine were the tissues where metal accumulation was the highest in A. purpuratus. Cd in digestive gland was always high, up to ∼250-fold higher than in other tissues, as previously reported in other bioindicator species for metal pollution. Fatty acids were good biomarkers when annual comparisons were performed, while metals when locations were compared. ENSO 2017 played an important role to disentangle A. purpuratus’ biological conditions and food sources. A. purpuratus from Paracas locations mostly showed higher metal concentrations in gills and digestive glands, and lower fatty acid concentrations in muscle than those from Sechura and Illescas Reserved Zone.
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Scallops and their potential predators were collected in Sechura Bay and in front of the Illescas... more Scallops and their potential predators were collected in Sechura Bay and in front of the Illescas Reserved Zone (north Peru), during El Niño-Southern Oscillation (ENSO) 2016, and analyzed for the metals chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb). This study showed that ~20% of the molluscs exceeded the maximum residual levels (MRLs) for human consumption in inorganic As, while ~30% of the crustaceans did. For Cd, around 10% and 40% of the molluscs and the crustaceans were above the MRLs, respectively. The cephalopod Octopus mimus exhibited As concentrations, but not Cd concentrations, that exceeded the MRLs. Cr, Ni, Cu, Zn and Pb in muscle exhibited generally concentrations below the MRLs. Integrated risk indices were estimated to determine if there is a health risk for consumption. Target hazard quotients (THQs) and total hazard indices (HIs) were mostly < 1, implying no human health risk. Provisional tolerable weekly intake (PTWI) for Cd was exceeded in Bursa ventricosa at Illescas Reserved Zone. Target cancer risks (TRs) for inorganic As were always higher than the threshold (1 × 10 −6), therefore an actual cancer risk is present.
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In order to understand the effect of different culture systems on Cd and Pb accumulation, suspend... more In order to understand the effect of different culture systems on Cd and Pb accumulation, suspended long-line and bottom cultures of Argopecten purpuratus were conducted during January until April 2010 (120 days). The Cd tissue levels were the highest at the middle of the experiment (30-d till 70-d) for suspended-cultured individuals, while bottom-cultured individuals showed an increasing trend. Gonad Pb levels were also higher during the same period for all cultures, while adductor muscle exhibited no considerable variations. Cd and Pb tissue concentrations were mainly greater in deeper cultures. There were no significant differences in Cd and Pb accumulation between individual sizes. The Cd and Pb levels in edible tissue (gonad + adductor muscle) did not exceed the EU and FDA maximum levels. Based on the target hazard quotient (THQ) and the provisional tolerance weekly intake (PTWI), no risk (THQ < 1 and %PTWI < 30) was found for human consumption.
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Conference Presentations by Iván Loaiza Alamo
El sector pesquero en el Perú ha sufrido considerables disminuciones en extracción y producción d... more El sector pesquero en el Perú ha sufrido considerables disminuciones en extracción y producción de recursos hidrobiólogicos en los últimos años, esto posiblemente por un mal manejo de las pesquerías y/o fenómenos naturales (ej. ENSO). La Ley General de Pesca N° 25977 establece entre diversos factores, la talla mínima de captura (TMC) para especies comerciales. El Terminal pesquero de Villa María del Triunfo (VMT) - Lima comercializa aproximadamente 120 TM de pescado fresco diariamente, y se estima que comercializa anualmente 143 mil TM de recursos pesqueros frescos. El objetivo de este trabajo fue determinar si las especies comerciales del Terminal de VMT cumplían con las TMC establecidas. Evaluaciones biométricas de 11 especies comerciales fueron realizadas en el Terminal de VMT, con ayuda de verniers (invertebrados), ictiómetros y cintas métricas (peces) durante 3 evaluaciones (E1, E2, E3), en Junio-Octubre, 2015. Siempre se consideró las TMC y el porcentaje máximo de tolerancia (PMT) por especie. Se evaluó diferentes tipos de medidas como longitud total (LT), de horquilla (LH), valvar (LV), diámetro del caparazón (DC) y ancho del cefalotórax (AC) como TMC para Coryphaena hippurus (Perico) LH=70cm; Scomber japonicus (Caballa) LT=32cm; Mugil cephalus (Lisa) LT=37cm; Sarda chiliensis (Bonito) LH=52cm; Merluccius gayi peruanos (Merluza) LT: 35 cm; Odontesthes regia regia (Pejerrey) LT: 14 cm; Loxechinus albus (Erizo verde) DC= 7cm; Romaleon polyodon (Cangrejo peludo) AC=11cm y Aulacomya atra (Choro) AV=6,5cm; Argopecten purpuratus (Concha de abanico) AV=6.5 cm y Platixanthus orbigni (Cangrejo violáceo) AC= no documentado. Los únicos recursos pesqueros en cumplir (al 100%) con las TMC fueron O. regia regia (LT: 16.49 ± 0.75 (E1) y L. albus ((DC: 9.41±0.54 (E1) y 9.43 ± 0.71 (E3)). Todas las demás especies (9) evaluadas presentaron especímenes por debajo de la TMC. El perico se encontró en comercialización (E1) durante su periodo de veda (01/05-30/09). Las especies con el PMTC más alto fueron la caballa con un 90.00% (E2) y perico con 86.58% (E2). Se encontró también una notable diferencia entre la E1 y E3 de bonito (37.36 ± 1.76 y 50.32 ± 3.97), lo que indica que hubo una mayor dispersión de los datos con respecto a su media. Otras especies como la lisa, merluza, cangejo peludo, concha de abanico presentaron alrededor de 76, 31, 59 y 60 individuos que superaron la TMC, y PTMCs de ≈40-50%. No existen TMC para el P. orbigni cangrejo violáceo en el Perú por lo que no se pudo comparar los datos obtenidos con su TMC respectiva. Se observó que esta especie es altamente comercializada en el Terminal de VMT.
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Pollution from human induced activities poses a worldwide problem. In coastal environments conseq... more Pollution from human induced activities poses a worldwide problem. In coastal environments consequences may threaten the survival of aquatic life (Philips and Rainbow, 1998). Filter-feeding animals, such as the blue mussel (Mytilus edulis) are particularly sensitive to toxic chemical compounds that make their way into the aquatic environment (O’Connor and Beliaeff, 1995). A preliminary experiment was conducted to investigate the effect of pyrethrin pesticide on the respiration rate of the blue mussel. A sample of 105 blue mussels was collected from the “sea wall” in Wimereux, France, at different locations, corresponding to low (LWL), intermediate (IWL) and high (HWL) water line. Half of them were exposed to a 5 µg.l-1 pyrethrin solution during 24 hours in a controlled laboratory environment. Three individuals were then grouped according to size (small: 25.8 ± 0.5mm and large: 39.2 ± 1.0mm) and placed in respiration chambers. Oxygen concentration and temperature were measured at 0, 20 and 40min. Respiration rate was calculated according to Clausen and Riisgård (1996). In addition, 36 large mussels were translocated in-situ: mussels from HWL were exchanged with mussels from LWL and left in their new environment for 24 hours. After this, half were exposed to the pesticide as described above.
In mussels that were not translocated, pyrethrin exposure did not seem to influence respiration rate significantly. No differences in respiration rate were found across different water line locations (LWL, IWL, HWL). A significant difference (p=0.02) was observed in respiration rates between small and large individuals. More remarkable was the observation of a statistically significant (p=0.01) difference in respiration rates for the mussels that were translocated from LWL to HWL. In these translocated mussels those that were exposed to the pesticide had a higher respiration rate than those not exposed to the pesticide. This was not the case for the mussels translocated from HWL to LWL. The significant difference in respiration rate may indicate that the mussels translocated to HWL were experiencing more stress. The HWL has a longer dry period than the LWL, which implies an additional stressor on mussels translocated from LWL to HWL. On the other hand, mussels that were translocated from the HWL to LWL did not experience this extra stress as they came from a generally more stressful environment. This could explain why those last mussels could cope more easily with the exposure to pyrethrin pesticide.
Although the number of observations was small, this experiment provides some evidence that pyrethrin pesticide may affect mussel physiology when it is not the only factor causing stress. Therefore the effect of pyrethrin should not be underestimated. It would therefore be worthwhile investigating the matter more elaborately, combining different stressors and increasing the number of observations.
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IV Congreso de Ciencias del Mar del Perú – CONCIMAR. Oral presentation: Influencia de la Salinida... more IV Congreso de Ciencias del Mar del Perú – CONCIMAR. Oral presentation: Influencia de la Salinidad en la Bioacumulación y Toxicidad de Metales Pesados en Pez Lubina “Dicentrarchus Labrax”
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Cadmium and copper are constituents of industrial and urban wastes that are considered a concern... more Cadmium and copper are constituents of industrial and urban wastes that are considered a concern because its environmental levels have risen steadily worldwide (Goering et al., 1995).
European sea bass, Dicentrarchus labrax, is an estuary and marine water (EMW) fish that is able to withstand gradients in many physical and chemical variables, including salinity, pH, dissolved oxygen, temperature, nutrients among others. In estuaries, the salinity is the controlling factor for the partitioning of contaminants, trace metals such as cadmium and copper change bioavailability and toxicity by complexation (Riba et al., 2003).
Therefore, the effect of salinity on the bioaccumulation and toxicity of copper and cadmium in D. labrax was determined at different exposure concentrations of Cu from 0 to 5100 μg L-1 and Cd from 0 to 20000 μg L-1 over a salinity range of 1, 2.5, 5, 10, 20, 28, 35‰ in juvenile individuals during a period of 10 days. The results showed a relationship between bioaccumulation and toxicity in terms of 96h-LC50 values (the lethal concentration where 50% of the population dies), where the salinity played an important role for both elements. At 2000 μgCd L-1 of exposure, the accumulation of Cd decreased considerably at higher salinities in liver and kidney, and concurrently LC50 values increased to 16256 μg L-1 (20‰), 18326 μg L-1 (28‰) and 24383 μg L-1 (35‰). On the contrary, the highest bioaccumulation of Cu was around the iso-osmotic point (10-20‰) where the LC50 values were elevated, 2619 μg L-1 at 10‰ and 6835 μg L-1 at 20‰. Generally, liver and kidney showed the highest concentration of Cd, followed by intestine and gills. For Cu, gills contained the highest concentrations and the lowest was found in intestine, kidney and liver exhibited noticeably variations and intermediate concentrations.
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XV Congreso Latinoamericano de Ciencias del Mar – COLACMAR. Oral presentation: Bioaccumulation of... more XV Congreso Latinoamericano de Ciencias del Mar – COLACMAR. Oral presentation: Bioaccumulation of cadmium and copper in juvenile European sea bass “Dicentrarchus labrax” following acute and chronic exposure
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Contamination by heavy metals in aquatic environments is a serious concern due to increasing huma... more Contamination by heavy metals in aquatic environments is a serious concern due to increasing human activities over the last decades. Moreover, productive areas such as estuaries have even been more affected because of the complex interaction between fluvial and marine processes, creating a stressful environment with gradients of salinity and other important parameters which can intensify negative effects of pollutants on biota such as euryhaline fish. (Oliva et al., 2012; Mieiro et al 2012). European sea bass (Dicentrarchus labrax l.) is a euryhaline species able to withstand a large variation in salinity and is considered as a bioindicador due to both economic and ecological importance (Joseph., et al 2011; Loizeau, 2001). Copper as essential micronutrient has important roles in cellular, enzymatical and protein mechanisms but is potentially toxic when its concentration increases above a certain threshold (Blanchard & Grosell, 2005; Grosell et al., 2007), and can even be more toxic than cadmium, a non-essential metal (Roméo et al., 2000) which is ubiquitous in environment and one of the most deleterious heavy metal pollutants (Nath et al., 1984 cited by Loaiza, 2011). Therefore, the effect of salinity on the acute toxicity of copper and cadmium in European sea bass D. labrax l. was examined to determine 96h-LC50 values (the lethal concentration where 50% of the population dies) at different exposure concentration of both metals (at 0 to 5100 μgCu L-1 and at 0 to 20000 μgCd L-1) over a broad salinity range (1, 2.5, 5, 10, 20, 28, 35‰) in juvenile sea bass during a period of 10 days. The results showed an important influence of the salinity in the toxicity in both elements, where for Cu mortality first decreased with increasing salinity but increased again at higher salinities and for Cd, mortality decreased continuously with increasing salinity, to a point where no reliable LC50 could be determined at the 2 highest salinities. In addition, it was observed that the individuals were affected in different ways. For instance Cu exposed fish at low salinity showed opened gills at die-off. Copper is readily taken up by the gill, where it inhibits the action of Na+/K+ adenosine triphosphatase, resulting in an osmoregulatory disturbance as Na+ is lost to the dilute external environment (Blanchard et al. 2006). In conclusion, the salinity influences the toxicity differently for Cu and Cd. This not only occurs due to the fact that salinity plays an important role in the speciation of pollutants and competition by cations in uptake processes, but as can be clearly seen in the case of Cu, also by the physiology of the fish that responds to the changes in the environment. Further research on the relationship between bio-accumulation of the metals and the mortality at different salinities is planned.
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In Sechura Bay, Peru bottom culture of the Peruvian scallop Argopecten purpuratus is an important... more In Sechura Bay, Peru bottom culture of the Peruvian scallop Argopecten purpuratus is an important economic activity with an export value of around 69 millions dollars in 2010 (SUNAT, 2010). However due to the nearby presence of cities, fishery industries, fishing piers and oil companies, this production area is subject to pollution and heavy metals are a concern (IMARPE 2007; INEI, 2008; ITP, 2008a; ITP, 2008b). Therefore, the bioaccumulation of cadmium and lead in Argopecten purpuratus of different size (50-65 and 70-80mm) was determinated, as well as its relationship with water and sediment concentration during January to April 2010 at Sechura Bay was established. The evaluation was performed in-situ, where 1700 specimens (50 - 65mm / 70 - 80mm) were extracted from the same area by semi-autonomous diving for planting randomly at a density of 10 ind.m-2. Samples of 500 individuals were collected monthly for biometric and heavy metals analysis in adductor muscle and gonad. Additionally, samples of seawater and sediment were collected with a Niskin Bottle and a plastic spatula respectively. Measurements of temperature, dissolved oxygen, electrical conductivity and redox potential were performed with the Multi-parameter HACH®. Individuals of both size groups showed similar concentrations in the bioaccumulation of cadmium in muscle adductor and lead in gonad. The lowest tissue Cd concentrations were observed in the adductor muscle. Results showed significant differences (α < 0.05) in Cd and Pb concentrations in adductor muscle and gonad in relation to size. The bioaccumulation of Cd in gonads of individuals from 50 to 65mm showed an increasing trend throughout the evaluation period, while individuals 70 to 80mm showed more variable trend. Pb always exhibited considerable variability. There were no significant correlations (α < 0.05) between the bioaccumulation of Cd and Pb in scallops and the concentration of Cd and Pb in bottom sediments. The abiotic variables; temperature and salinity were directly related with the bioaccumulation of Cd and Pb in Argopecten purpuratus. Although traces of cadmium and lead are present we conclude that the values in edible tissue of scallop are below the maximum levels of the European Union (EU) and World Health Organization (WHO).
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European sea bass Dicentrarchus labrax was acutely exposed to Cd concentrations of 17.79, 142.33 ... more European sea bass Dicentrarchus labrax was acutely exposed to Cd concentrations of 17.79, 142.33 and 177.92 μM and Cu concentration of 31.47, 75.54 and 80.26 μM over a 10-day period, and to chronically Cd concentration of 14.46 μM and a Cu concentration of 10.76 μM (according to 10% of 96h-LC50 obtained values at 20‰) for a short exposure period (SEP) of 10 days and long period (LEP) of 28 days, both experiments were conducted at 20‰. Survival time in relation to the tissue Cu does not show a clear relationship between tissue Cu and time to death, tissue concentrations in dead fish was in the same range as concentrations in the survivors. However for Cd, a significant difference were observed in tissue Cd, the dead individuals exhibited accumulated Cd about of 5 to 18-fold more in liver, 10-31-fold in kidney, 12-31-fold in gill and 1.5-29-fold in intestine than in surviving individuals, this seems to explain partially the cause of death. Among dead and surviving individuals, a clear difference in speed of accumulation (μmol/g dwt /day) was apparent, accumulation rates were extremely high in dead fish, such as 2.417 ± 1.774 and 10.076 ± 11.097 in kidney compared to lower values than 0.035 and 0.026 of exposed survivors to Cd and Cu respectively. All examined tissues (liver, kidney, gill and intestine) showed significantly higher Cd accumulation rates at the two highest acute exposures compared to chronic exposed fish (with the exception of kidney at 177. 92 μM), whereas for Cu, intestine and gill showed the same pattern for all acute exposures, and kidney and liver only over 80.26 and 75.54 μM exposure respectively. Among the different exposure periods, liver, gill and intestine Cd were significantly higher over the LEP, while kidney does not show variations. For Cu, liver and intestine from the LEP also exhibited significantly higher concentrations compared to those at SEP. Kidney and gill showed the opposite response but not statistically different (SEP > LEP in Cu concentrations).
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Sechura Bay receives domestic and industrial discharges from nearby cities, fishery industries an... more Sechura Bay receives domestic and industrial discharges from nearby cities, fishery industries and oil companies. Bottom and suspended long-line culture are the two common systems performed in scallop aquaculture, the latter has been more implemented because leads to high growth rates, less mortality and major production. The aim of this study was to investigate the Cd and Pb accumulation in gonad and muscle of A. purpuratus during January to April 2010. For the experiment among systems, a first group of 1800 medium size (50-65 mm) individuals were distributed in pearl nets at 3 (PN3) and 6 (PN6) meters depth, and in a corral at the bottom (12m) (CB12M). A second group of 600 large size (70-80 mm) individuals were distributed in a second corral (CB12L) for the experiment among sizes. The remaining 500 individuals (both range size) were considered as control. Tissue Cd levels were the highest during the 30-70 days for PN3 and PN6, while an increasing trend was observed in CB12M and CB12L. Gonad [Pb] was also higher during the same period for all cultured systems. Muscle exhibited no considerably variations in [Pb]. Among systems or depths, tissue [Cd] and [Pb] were greater in deeper culture systems. PN6 exhibited significantly higher gonad Cd (March) and Pb (March and April) levels compared to PN3, and in muscle [Pb] during February and March. CB12M led to significantly higher muscle [Cd]. There were no significant differences in Cd and Pb accumulation between range sizes.
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Teaching Documents by Iván Loaiza Alamo
Presentation for the Course: Integrated Ecosystem Management and Ecological Engineering. Oceans &... more Presentation for the Course: Integrated Ecosystem Management and Ecological Engineering. Oceans & Lakes programme, 2013-I.
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Presentation for the Course: Global Change and Coastal Hazard Mitigation. Oceans & Lakes programm... more Presentation for the Course: Global Change and Coastal Hazard Mitigation. Oceans & Lakes programme, 2012-II.
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Presentation for the Course: Ecotoxicology and Risk Assessment. Oceans & Lakes programme, 2012-II.
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Presentation for the Course: Law and Ethics on Conservation of Aquatic Systems. Oceans & Lakes pr... more Presentation for the Course: Law and Ethics on Conservation of Aquatic Systems. Oceans & Lakes programme, 2012-I.
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Clase Modelo: Contaminación de ecosistemas acuáticos: Uso de Bioensayos (in-situ & lab), Facultad... more Clase Modelo: Contaminación de ecosistemas acuáticos: Uso de Bioensayos (in-situ & lab), Facultad de Biología Marina, UCSUR 2014-I.
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Papers by Iván Loaiza Alamo
Conference Presentations by Iván Loaiza Alamo
In mussels that were not translocated, pyrethrin exposure did not seem to influence respiration rate significantly. No differences in respiration rate were found across different water line locations (LWL, IWL, HWL). A significant difference (p=0.02) was observed in respiration rates between small and large individuals. More remarkable was the observation of a statistically significant (p=0.01) difference in respiration rates for the mussels that were translocated from LWL to HWL. In these translocated mussels those that were exposed to the pesticide had a higher respiration rate than those not exposed to the pesticide. This was not the case for the mussels translocated from HWL to LWL. The significant difference in respiration rate may indicate that the mussels translocated to HWL were experiencing more stress. The HWL has a longer dry period than the LWL, which implies an additional stressor on mussels translocated from LWL to HWL. On the other hand, mussels that were translocated from the HWL to LWL did not experience this extra stress as they came from a generally more stressful environment. This could explain why those last mussels could cope more easily with the exposure to pyrethrin pesticide.
Although the number of observations was small, this experiment provides some evidence that pyrethrin pesticide may affect mussel physiology when it is not the only factor causing stress. Therefore the effect of pyrethrin should not be underestimated. It would therefore be worthwhile investigating the matter more elaborately, combining different stressors and increasing the number of observations.
European sea bass, Dicentrarchus labrax, is an estuary and marine water (EMW) fish that is able to withstand gradients in many physical and chemical variables, including salinity, pH, dissolved oxygen, temperature, nutrients among others. In estuaries, the salinity is the controlling factor for the partitioning of contaminants, trace metals such as cadmium and copper change bioavailability and toxicity by complexation (Riba et al., 2003).
Therefore, the effect of salinity on the bioaccumulation and toxicity of copper and cadmium in D. labrax was determined at different exposure concentrations of Cu from 0 to 5100 μg L-1 and Cd from 0 to 20000 μg L-1 over a salinity range of 1, 2.5, 5, 10, 20, 28, 35‰ in juvenile individuals during a period of 10 days. The results showed a relationship between bioaccumulation and toxicity in terms of 96h-LC50 values (the lethal concentration where 50% of the population dies), where the salinity played an important role for both elements. At 2000 μgCd L-1 of exposure, the accumulation of Cd decreased considerably at higher salinities in liver and kidney, and concurrently LC50 values increased to 16256 μg L-1 (20‰), 18326 μg L-1 (28‰) and 24383 μg L-1 (35‰). On the contrary, the highest bioaccumulation of Cu was around the iso-osmotic point (10-20‰) where the LC50 values were elevated, 2619 μg L-1 at 10‰ and 6835 μg L-1 at 20‰. Generally, liver and kidney showed the highest concentration of Cd, followed by intestine and gills. For Cu, gills contained the highest concentrations and the lowest was found in intestine, kidney and liver exhibited noticeably variations and intermediate concentrations.
Teaching Documents by Iván Loaiza Alamo
In mussels that were not translocated, pyrethrin exposure did not seem to influence respiration rate significantly. No differences in respiration rate were found across different water line locations (LWL, IWL, HWL). A significant difference (p=0.02) was observed in respiration rates between small and large individuals. More remarkable was the observation of a statistically significant (p=0.01) difference in respiration rates for the mussels that were translocated from LWL to HWL. In these translocated mussels those that were exposed to the pesticide had a higher respiration rate than those not exposed to the pesticide. This was not the case for the mussels translocated from HWL to LWL. The significant difference in respiration rate may indicate that the mussels translocated to HWL were experiencing more stress. The HWL has a longer dry period than the LWL, which implies an additional stressor on mussels translocated from LWL to HWL. On the other hand, mussels that were translocated from the HWL to LWL did not experience this extra stress as they came from a generally more stressful environment. This could explain why those last mussels could cope more easily with the exposure to pyrethrin pesticide.
Although the number of observations was small, this experiment provides some evidence that pyrethrin pesticide may affect mussel physiology when it is not the only factor causing stress. Therefore the effect of pyrethrin should not be underestimated. It would therefore be worthwhile investigating the matter more elaborately, combining different stressors and increasing the number of observations.
European sea bass, Dicentrarchus labrax, is an estuary and marine water (EMW) fish that is able to withstand gradients in many physical and chemical variables, including salinity, pH, dissolved oxygen, temperature, nutrients among others. In estuaries, the salinity is the controlling factor for the partitioning of contaminants, trace metals such as cadmium and copper change bioavailability and toxicity by complexation (Riba et al., 2003).
Therefore, the effect of salinity on the bioaccumulation and toxicity of copper and cadmium in D. labrax was determined at different exposure concentrations of Cu from 0 to 5100 μg L-1 and Cd from 0 to 20000 μg L-1 over a salinity range of 1, 2.5, 5, 10, 20, 28, 35‰ in juvenile individuals during a period of 10 days. The results showed a relationship between bioaccumulation and toxicity in terms of 96h-LC50 values (the lethal concentration where 50% of the population dies), where the salinity played an important role for both elements. At 2000 μgCd L-1 of exposure, the accumulation of Cd decreased considerably at higher salinities in liver and kidney, and concurrently LC50 values increased to 16256 μg L-1 (20‰), 18326 μg L-1 (28‰) and 24383 μg L-1 (35‰). On the contrary, the highest bioaccumulation of Cu was around the iso-osmotic point (10-20‰) where the LC50 values were elevated, 2619 μg L-1 at 10‰ and 6835 μg L-1 at 20‰. Generally, liver and kidney showed the highest concentration of Cd, followed by intestine and gills. For Cu, gills contained the highest concentrations and the lowest was found in intestine, kidney and liver exhibited noticeably variations and intermediate concentrations.