Heavy metal accumulation in marine fishes in Porirua Harbour

<p>Heavy metal or metalloids are common pollutants that are discharged into the aquatic environment by a variety of natural and anthropogenic sources, and have the ability to bio- accumulate in the tissues of marine organisms. Fish are among the top consumers in aquatic ecosystems and are widely recognised as bio-indicators for heavy metal pollution. Accumulation of heavy metals is influenced by factors such as species, age, size, and trophic level and can be found in various tissue types, such as muscle and liver tissue. In addition, contaminated fish can pose a threat to human consumers as they can cause acute and chronic disorders. Estuaries are particularly vulnerable to heavy metal pollution as they are as they are a direct recipient of raw sewage, industrial, residential and farming runoff. Estuaries provide essential habitat for a range of species, including fishes that occupy estuaries permanently or seasonally for breeding. Te Awarua-o-Porirua Harbour (Porirua Harbour) is the largest, and the most significant estuary in the southern North Island of New Zealand. It is a 807 hectare tidal lagoon estuary next to Porirua City and consists of two distinct estuary arms, Onepoto and Pauatahanui. Porirua Harbour once boasted a healthy and diverse ecosystem that supported fishes that are prized by the Ngati Toa as kaimoana. However, heavy metal contamination has become problematic following the introduction of intensive industry and development in the harbour catchment. The aim of this research was to 1) quantify levels of four heavy metals (Cu, Zn, Pb, and Hg) in the tissue (muscle and liver) of yellow belly flounder (Pātiki, tōtara, Rhombosolea leporina), sand flounder (Pātiki, Rhombosolea plebeia), speckled sole (Peltorhamphus latus), rig shark (Pioke, Makō, Mangō, Mustelus lenticulatus), short-tailed stingray (Whai, Dasyatis brevicaudata), and eagle ray (Whai keo, Myliobatis tenuicaudatus) caught in Porirua Harbour, and look for differences between sexes, tissue types, as well as effects of size and age, 2) examine each fish sampled for general metrics of health (parasite load, skin lesions, etc.) as well as diet, and look for relationships with body burdens of metals, 3) examine maternal offloading of heavy metals from pregnant rig shark to near-term embryos, 4) examine the movement of benthic fishes between the two estuary arms using mark/recapture methods. To assess heavy metal accumulation and movement in benthic fishes, fish were collected and/or tagged over a 4-month period in 2018 (March-August) across 8 sites in Porirua Harbour. Tagged fish were unable to be recovered so conclusions were left undetermined. Overall, liver tissue had the highest levels of heavy metal concentration, with the expectation of Hg being elevated in the muscle tissue of rig shark. There were significant differences observed for species, fish size, with smaller fishes having higher Cu concentration, and larger fish having higher Hg concentrations. There was little to no relationship observed between Zn and Pb concentrations in this study. To investigate the role of maternal offloading of heavy metals from maternal rig shark to their near-term embryos, embryos were collected from the uterus of 13 pregnant females and assessed individually for heavy metal (Cu, Zn, Pb, Hg) concentrations in muscle tissue. Overall, there was no relationship for Cu between the amount in embryos and either the maternal concentration or size. However, Zn and Pb concentration in rig shark embryos were positively related with maternal size. Therefore, size explained embryo Zn and Pb concentration in rig shark embryos, and embryo Hg concentrations were explained by maternal concentrations and size, suggesting maternal offloading of Hg might be occurring in rig shark. The results of this thesis support prior research findings of heavy metal accumulation depending primarily on the tissue type, fish size and is metal and species specific. This research adds to the currently lacking information on heavy metal accumulation in these study species, and will aid the ongoing monitoring of Porirua Harbour by Greater Wellington Regional Council and Porirua City Council.</p>

Heavy metal accumulation in marine fishes in Porirua Harbour

<p>Heavy metal or metalloids are common pollutants that are discharged into the aquatic environment by a variety of natural and anthropogenic sources, and have the ability to bio- accumulate in the tissues of marine organisms. Fish are among the top consumers in aquatic ecosystems and are widely recognised as bio-indicators for heavy metal pollution. Accumulation of heavy metals is influenced by factors such as species, age, size, and trophic level and can be found in various tissue types, such as muscle and liver tissue. In addition, contaminated fish can pose a threat to human consumers as they can cause acute and chronic disorders. Estuaries are particularly vulnerable to heavy metal pollution as they are as they are a direct recipient of raw sewage, industrial, residential and farming runoff. Estuaries provide essential habitat for a range of species, including fishes that occupy estuaries permanently or seasonally for breeding. Te Awarua-o-Porirua Harbour (Porirua Harbour) is the largest, and the most significant estuary in the southern North Island of New Zealand. It is a 807 hectare tidal lagoon estuary next to Porirua City and consists of two distinct estuary arms, Onepoto and Pauatahanui. Porirua Harbour once boasted a healthy and diverse ecosystem that supported fishes that are prized by the Ngati Toa as kaimoana. However, heavy metal contamination has become problematic following the introduction of intensive industry and development in the harbour catchment. The aim of this research was to 1) quantify levels of four heavy metals (Cu, Zn, Pb, and Hg) in the tissue (muscle and liver) of yellow belly flounder (Pātiki, tōtara, Rhombosolea leporina), sand flounder (Pātiki, Rhombosolea plebeia), speckled sole (Peltorhamphus latus), rig shark (Pioke, Makō, Mangō, Mustelus lenticulatus), short-tailed stingray (Whai, Dasyatis brevicaudata), and eagle ray (Whai keo, Myliobatis tenuicaudatus) caught in Porirua Harbour, and look for differences between sexes, tissue types, as well as effects of size and age, 2) examine each fish sampled for general metrics of health (parasite load, skin lesions, etc.) as well as diet, and look for relationships with body burdens of metals, 3) examine maternal offloading of heavy metals from pregnant rig shark to near-term embryos, 4) examine the movement of benthic fishes between the two estuary arms using mark/recapture methods. To assess heavy metal accumulation and movement in benthic fishes, fish were collected and/or tagged over a 4-month period in 2018 (March-August) across 8 sites in Porirua Harbour. Tagged fish were unable to be recovered so conclusions were left undetermined. Overall, liver tissue had the highest levels of heavy metal concentration, with the expectation of Hg being elevated in the muscle tissue of rig shark. There were significant differences observed for species, fish size, with smaller fishes having higher Cu concentration, and larger fish having higher Hg concentrations. There was little to no relationship observed between Zn and Pb concentrations in this study. To investigate the role of maternal offloading of heavy metals from maternal rig shark to their near-term embryos, embryos were collected from the uterus of 13 pregnant females and assessed individually for heavy metal (Cu, Zn, Pb, Hg) concentrations in muscle tissue. Overall, there was no relationship for Cu between the amount in embryos and either the maternal concentration or size. However, Zn and Pb concentration in rig shark embryos were positively related with maternal size. Therefore, size explained embryo Zn and Pb concentration in rig shark embryos, and embryo Hg concentrations were explained by maternal concentrations and size, suggesting maternal offloading of Hg might be occurring in rig shark. The results of this thesis support prior research findings of heavy metal accumulation depending primarily on the tissue type, fish size and is metal and species specific. This research adds to the currently lacking information on heavy metal accumulation in these study species, and will aid the ongoing monitoring of Porirua Harbour by Greater Wellington Regional Council and Porirua City Council.</p>

Levels of heavy metals in pelagic and benthic fish species in river Nun at Amassoma, Bayelsa State, Nigeri

The heavy metals content in three fish species from River nun Amassoma axis was investigated. This was done in order to gauge the concentration of heavy metals in fish tissues and to estimate the safety of consuming these fish species on human health. Three species (pelagic and benthic fishes) were collected from local fishermen at the landing jetty and analyzed for heavy metals in the soft tissues using standard procedures. The heavy metals investigated are Cadmium (Cd), Nickel (Ni), Lead (Pb) and Chromium (Cr). Result indicates that Cd>Ni>Pb>Cr in the fish samples analyzed while Chrysichthys auratus showed the greatest abundant characteristics of Cr, Pb, Ni, Cd. There was no significant difference (P>0.05) in concentrations of Cr and Ni for all fish species. However, the results showed that there is a significant difference (P<0.05) in Pb concentration between Chrysichthys auratus, Chrysichthys aluuensis and Petrocephalus bane bane. Cd concentration in the fish species reveal that there is a significant difference (P<0.05) between Chrysichthys auratus and Petrocephalus bane bane but no significant difference (P>0.05) between Chrysichthys auratus and Chrysichthys aluuensis and between Chrysichthys aluuensis and Petrocephalus bane bane Heavy metal in the fish species showed that Chrysichthys auratus>Chrysichthys aluuensis>Petrocephalus bane bane. All metal characteristics were lower than the suggested WHO permissible limit. Benthic fish species have a greater heavy metal concentration than the pelagic fishes. Based on the observation from this study, the continuous and sustained consumption of Chrysichthys auratus and indeed benthic fish species possess a higher risk to health, while Cd poisoning in fish is most culpable of pollution in River Nun at Amassoma. axis.

First record and extended distribution of Otothyropsis piribebuy (Loricariidae: Hypoptopomatinae) in Brazil

Cascudinhos are a group of small benthic fishes included in the Hypoptopomatinae subfamily, inhabiting small to moderate streams and rivers within the Neotropical region, from Venezuela to Northern Argentina. Until now, Otothyropsis piribebuy originally described from the rio Paraguay basin, in Paraguay, is the only species of the genus not recorded in Brazil. Recent samples in the rio Tererê, rio Paraguay basin, Brazil, revealed a population of Otothyropsis with uncertain taxonomic identity. Therefore, the study aimed to unveil the distribution of Otothyropsis within Brazilian territory. External morphology, osteology, measurements, and counts (plates, teeth, and rays) of these specimens from rio Tererê were compared to data from the original description of O. piribebuy, and also with specimens of O. piribebuy sampled in Paraguayan territory. Observations indicated no differences among the analyzed specimens. Furthermore, a Principal Component Analysis (PCA), carried out using log-transformed measures from Brazilian and Paraguayan specimens, showed no separation of these populations, also indicating that all analyzed specimens pertain to the same species. Based on this, a prediction map of distribution, using Maximum Entropy, was produced. The correct identification of spatial range of occurrence is an essential step to ensure the conservation of species, and the extended distribution of Otothyropsis piribebuy was confirmed, enhancing the list of neotropical fish from Brazil.

A quantitative assessment of the diel influence on the cryptobenthic fish assemblage of the shallow Mediterranean infralittoral zone

Cryptobenthic fishes are an underestimated and probably important component of coastal marine ecosystems that are usually overlooked by standard methods for collecting and studying benthic fishes. Studies focusing on cryptobenthic fishes have been rare and all have been based on samples taken during daytime. The present study tested the difference in epibenthic and cryptobenthic fish composition, diel differences in cryptobenthic fish assemblage and diel shifts of infralittoral fish species between hidden and open bottom spaces. It also looked for the significant habitat variables structuring the cryptobenthic fish assemblage. The daylight, sunset and night samples of epibenthic and cryptobenthic fish assemblages were collected from 78 squares of 1 m2 shallow water plots (0.5 to 3 m) on Brač island in the eastern Adriatic. The study recorded 27 species, among which the family Gobiidae dominated fish diversity with 14 species. Cryptobenthic specimens highly outnumbered epibenthic specimens, with a ratio of 7.5 to 1. Species composition of cryptobenthic and epibenthic fish assemblages differed significantly. No diel variation in composition, species richness or abundance of the cryptobenthic fish assemblage was detected. Occurrence frequencies in hidden and open bottom spaces of ambivalent species did not change significantly between times of day, so no dial switches between open and hidden places were apparent. In combination, these results suggest that the cryptobenthic fish assemblage has diel stability and is mostly composed of permanent inhabitants of hidden spaces with domination of miniature gobies. Significant habitat variables for species occurrence were the presence of multiple layers, bottom inclination and the presence of cobbles, while depth also had a large but not significant effect.