Lagoon Fish Research Articles

When tourism intersects traditional rural livelihoods: A case study on lagoon fishing in Thừa Thiên Huế Province, Vietnam

ABSTRACT Tourism development is an oft-touted strategy to enhance the livelihoods of local residents and reduce their dependence on resources. This study explores the determinants of lagoon fishermen’s participation in tourism-related activities and evaluates whether tourism is an alternative livelihood option for Thừa Thiên Huế Province, Vietnam. We employed propensity score matching to analyze the survey data from 265 households in the coastal area of the lagoon. Our study indicates that tourism cannot provide a sustainable livelihood for local residents if the locals forego their traditional livelihood practices and completely transform the region into a tourist attraction, even though it can contribute to increasing household income. Other factors, such as low levels of education and larger travel distances between the lagoons and existing tourist areas, are the primary barriers to fishermen participation in tourism. Finally, we analyzed the related policy and managerial implications to improve tourism and diversify the locals’ livelihoods.

Recolonization origin and reproductive locations, but not isolation from the sea, lead to genetic structure in migratory lagoonal fishes

The assessment of connectivity in marine ecosystems is a requirement to adequate fisheries management. In this study we have selected two commercially exploited migratory species, European perch (Perca fluviatilis) and European smelt (Osmerus eperlanus), to evaluate the connectivity between the Curonian Lagoon and the coastal Baltic Sea. Our results indicate that isolation between the coastal lagoon and the adjacent sea area does not lead to the formation of genetic structure in migratory fish species. However, both species do register subpopulations coexisting in the area without interbreeding. This indicates that the fisheries management for migratory fishes in coastal lagoons affects a wider area than just the coastal lagoon. European perch, being a postglacial recolonizer from various refugees, has four different subpopulations, while the mechanism that maintains this division remains unexplored. The feeding migrations of European perch to the coastal zone suggest that the reproduction might occur elsewhere and that the factors for genetic structure suggested at the Baltic Sea scale might operate during these migrations. For European smelt, we discuss the existence of two different ecotypes, one lagoonal and one diadromous, and the different registered spawning locations as explicative causes for the maintenance of two genetically divergent clusters. The lagoonal ecotype reproduces and spawns inside the Curonian Lagoon while the diadromous one lives in the open Baltic Sea, performing spawning migrations to the lagoon and the mouth of Nemunas river, thus, maintaining the genetic divergence among them. However, our results indicate that there are no differences in size between both clusters, while the lagoonal population is expected to be smaller, forbidding the determination of two genetically different ecotypes. We conclude that there are no geographically and genetically separated populations of these two species in the lagoon-sea- terrestrial inlets continuum, and unified stock management for the coastal Baltic Sea and the Curonian lagoon is required.

Short-Range Movement Pattern of Amphidromous Lagoon Fish Schools: Ecological Applications

High-resolution multibeam sonar allows estimating movements of pelagic fish schools at short range. Taking advantage of this methodology, we calculated a Straightness Index (SI) to quantify the proportion of schools migrating actively from those residents in lagoon channels. This information enhances our knowledge of both fish school displacements and migration processes, which are essential to improve our understanding of ecosystem functioning. Most fish schools (65%) exhibited a SI value demonstrating oriented swimming behavior through the channels displayed by schools reaching the sea during fall migration. This trend appears as an intrinsic property of school movements, allowing monitoring of the school migration process in a channel to provide information for manager vs. fishing regulation measures or lagoon planning. The result strengthens the ‘multi-transit’ hypothesis, as 35% of schools show sinuous trajectories representative of schools staying in the channel or displaying high exploratory behaviors. Lastly, the fish school Exploration Swimming Speed (ESS) was tested as a fishery-independent sampling method to evaluate the proportion of different fish species monitored using hydroacoustics. This approach demonstrates the interest in using swimming behavioral characteristics of fish schools for ecological and management purposes.

Energy Condition of Subsistence‐Harvested Fishes in Arctic Coastal Lagoons

AbstractIn Arctic Alaska, Indigenous and rural residents depend on wild‐harvested foods for sustenance and the subsistence lifestyle is integral to their culture. Marine and diadromous fishes, which often occupy coastal lagoon habitats, are relied upon for subsistence harvest, particularly Pacific salmon, whitefishes (Coregoninae), cods (Gadidae), and flounder species (Pleuronectidae). However, little research has been conducted that assesses the energetic condition of these fishes, which are harvested by the tens of thousands annually. The effects of accelerating climate change and human development on the metabolic rates, diet, body condition, and energy density of fish is of great concern because these effects will, in turn, affect the people who depend on these species for food security. Consequently, we characterized energy density and percentage of lipid, water, and protein content of 10 fish species in four coastal lagoons within Cape Krusenstern National Monument, Alaska. We found that whitefishes, particularly Bering Cisco Coregonus laurettae and Least Cisco C. sardinella exhibited the highest energy density, percentage of lipid, and percentage of protein content, significantly greater than that of marine cod and flounder species, Fourhourn Sculpin Myoxocephalus quadricornis, freshwater Pond Smelt Hypomesus olidus, and values from other regional species that have been in published literature. Additionally, when the relative mean abundance and body weight of each species was taken into account, total energy value by availability in the lagoons was highest for whitefishes when compared with marine taxa and the freshwater Pond Smelt. Given the impending effects of climate change and coastal construction in the region, it will be important to monitor the energy condition of lagoon fishes to ensure their quality and availability for subsistence harvesters.

Freshwater input and ocean connectivity affect habitats and trophic ecology of fishes in Arctic coastal lagoons

Freshwater input and ocean connectivity affect habitats and trophic ecology of fishes in Arctic coastal lagoons

Status of the fishery of Jaffna lagoon, Sri Lanka

Jaffna lagoon (9° 50' N and 79° 50' E to 9°20' N and 80° 30' E) is the largest lagoon in Sri Lanka and it provides many services including fishing opportunities to the people in northern Sri Lanka. However, the status of the Jaffna lagoon fishery is not fully known at present due to the lack of detailed studies over the last 40 years. Therefore, this study was designed to fulfil this research gap. Both primary data and secondary data were used in this study. Primary data, including catch and fishing effort were collected at three major landing sites, Gurunagar, Paasaiyoor, and Kachchai by making fortnight field visits from March to December 2019. Secondary data of the monthly total catch and fishing effort were obtained from the district fisheries offices in Jaffna and Kilinochchi districts in order to estimate MSY and FMSY. This study revealed that ~5340 fishers confined to 39 landing sites were actively engaged in lagoon fishing during the study period using 12 different fishing methods. Fyke nets (71%) followed by stake nets (10%), lagoon seines, and lagoon boat seines (6%) are the widely used fishing methods in lagoon fisheries. Catch rates of major fishing gear were calculated and recorded as kg fisherman-1, day-1. Stake net (37kg ± 7) reported a significantly higher catch rate than fyke net (18kg ± 3), seine net (17kg ± 6), and crab net (16kg ± 3) (p<0.05; ANOVA). Both mechanized (59%) and non-mechanized (41%) crafts are used in the lagoon fishing practices. Forty-six commercially important finfish and shellfish species belonging to 25 families were identified in the lagoon catches of which Penaeidae made the highest percentage contribution (27%), followed by Siganidae (13%), Mugilidae (11%), Lethrinidae (10%), and Gerreidae (9%). Analysis of secondary data confirmed the increasing trend of fishing effort since 2009 but the total landings declined gradually after reporting its maximum value of 6958 Mt. in 2012. A rough estimate of maximum sustainable yield of the fishery of Jaffna lagoon was 6,694 Mt with the annual fishing effort (FMSY) of 1007 crafts. As the current fishing effort is higher than the FMSY, input control measures are recommended to utilize the lagoon fishery resources in a sustainable manner.

Contextualizing methodology and measuring reflected material wellbeing of a fishing community in Sri Lanka

The present study develops an approach that consists of contextually specific, methodological stances to measure the material wellbeing and apply it to identify the wellbeing variations among four different fishing profiles of the Rekawa fishing community in Sri Lanka. One hundred and sixty fishers were randomly selected from “one-day fishing”, “multiday fishing”, “beach-seine”, and “lagoon fishing” profiles representing forty from each group. Material wellbeing is a profoundly important aspect of the overall welfare that consists of economic sustainability, healthy living, good and quality education, and access to nutritious food. Besides, acquiring and preserving material wellbeing can be considered an essential objective of the fishing community, but lay reflections on wellbeing experiences can be different because each fishing profile is attributed to different community characteristics. Development interventions are thus required to be adjusted in line with the unique socio-cultural characteristics of the community.

Influence of past and current factors on the beta diversity of coastal lagoon fish communities in South America

AbstractAimFish community composition is shaped by current and historical factors. In recently formed ecosystems, however, as the Quaternary coastal lagoons of South America, the influence of historical factors has less frequently been investigated. The low rate of endemism in these lagoons suggests a limited role for speciation while their dynamic formation history suggests local extinction and dispersal limitation could have affected present species composition. We aimed to assess the influence of past and current factors on the beta diversity of those communities and explore the main processes involved.LocationAtlantic coast of South America.TaxonFishes (173 species).MethodsWe built a dataset of species occurrence in 129 lagoons across eight freshwater ecoregions of the world (FEOWs) located between latitudes 0° and 36°, and calculated beta diversity (βjac) and its turnover (βjtu) and nestedness (βjne) components. We used a partial Mantel test and multiple regressions on distance matrices to evaluate the importance of past and current factors, and of geographical distance in determining beta diversity. Past variables were those representing the historical freshwater habitat during the last glacial maximum (LGM), and contemporary variables were those related to current habitat.ResultsWe found high values of βjac within the FEOWs, with βjtu prevailing over βjne. Both past (palaeodrainage) and current (drainage area, salinity and lagoon area) factors affected species dissimilarity (βjac = 46%) and its components (βjtu = 44% and βjne = 20%), although explanation was, in part, shared with geographical distance. Individually, the influence of past factors was prevalent in beta diversity and its components.Main conclusionsThe large influence of the past factors on beta diversity suggests that major changes in the availability of freshwater habitats and connectivity since the Pleistocene must have affected the colonization, extinction and recolonization processes of fishes along the eastern coast of South America. We suggest that the high beta diversity values result from limited dispersal after extinctions in the LGM. The dissimilar freshwater fish communities currently seen result from heterogeneous subsets of the regional species pool that persisted in landscape refuges during past sea level increases and then recolonized coastal lagoons.

Fshr: a fish sex-determining locus shows variable incomplete penetrance across flathead grey mullet populations.

SummaryWhole-genome sequencing data were produced from a single flathead grey mullet female and assembled into a draft genome sequence, whereas publicly available sequence data were used to obtain a male draft sequence. Two pools, each consisting of 60 unrelated individuals, respectively, of male and female fish were analyzed using Pool-Sequencing. Mapping and analysis of Pool-Seq data against the draft genome(s) revealed >30 loci potentially associated with sex, the most promising locus of which, encoding the follicle-stimulating hormone receptor (fshr) and harboring two missense variants, was genotyped on 245 fish from four Mediterranean populations. Genotype data showed that fshr represents a previously unknown sex-determining locus, although the incomplete association pattern between fshr genotype and sex-phenotype, the variability of such pattern across different populations, and the presence of other candidate loci reveal that a greater complexity underlies sex determination in the flathead grey mullet.

Scale sensitivity of environmental effects on the temporal beta diversity of fishes in tropical coastal lagoons

Disentangling multilevel sources of variation is critical for understanding of diversity patterns in high-variability environments. We investigated the scale sensitivity of short-term environmental effects on the temporal beta diversity of fishes in 3 tropical coastal lagoons in Southeastern Brazil. Environmental effects were investigated at 3 hierarchical levels (local, zone, and lagoon). An AICc-based model selection was applied to generalized linear mixed models relating abundance-based beta diversity (Bray-Curtis dissimilarity; βBC) to environmental distances and random effects for other sources of variability. Abundance gradients (βBC-GRA) contributed more for βBC at all hierarchical levels, most likely due to random changes in the abundances of numerous rare marine-origin species. The temporal and spatial marine influences favored the balanced variation in the abundance of different species (βBC-BAL), probably by allowing for marine species with different environmental tolerances and requirements. The freshwater vs. marine influences were primarily represented by short-term effects of salinity changes at the local and zone levels and tide height and accumulated rainfall at the lagoon level. Other environmental effects (e.g. pH and transparency) were representative of that balance depending on the βBC component and hierarchical level. Random effects for morphometric features (local level, width of the connections between zones; lagoon level, distance from the ocean) and climate-related factors (local and zone levels, wind intensity and accumulated rainfall; lagoon level, changing seasons) were also relevant for the relationships between environmental variability and βBC. This study evidenced major scale-related mechanisms driving the temporal beta diversity of fishes in tropical coastal lagoons.

Allometric relationships in morphological traits associated with foraging, swimming ability, and predator defense reveal adaptations toward brackish and freshwater environments in the threespine stickleback.

Freshwater colonization by threespine stickleback has led to divergence in morphology between ancestral marine and derived freshwater populations, making them ideal for studying natural selection on phenotypes. In an open brackish–freshwater system, we previously discovered two genetically distinct stickleback populations that also differ in geometric shape: one mainly found in the brackish water lagoon and one throughout the freshwater system. As shape and size are not perfectly correlated, the aim of this study was to identify the morphological trait(s) that separated the populations in geometric shape. We measured 23 phenotypes likely to be important for foraging, swimming capacity, and defense against predation. The lateral plate morphs in freshwater displayed few significant changes in trait sizes, but the low plated expressed feeding traits more associated with benthic habitats. When comparing the completely plated genetically assigned populations, the freshwater, the hybrids, the migrants and the lagoon fish, many of the linear traits had different slopes and intercepts in trait‐size regressions, precluding our ability to directly compare all traits simultaneously, which most likely results from low variation in body length for the lagoon and migrant population. We found the lagoon stickleback population to be more specialized toward the littoral zone, displaying benthic traits such as large, deep bodies with smaller eyes compared to the freshwater completely plated morph. Further, the lagoon and migrant fish had an overall higher body coverage of lateral plates compared to freshwater fish, and the dorsal and pelvic spines were longer. Evolutionary constraints due to allometric scaling relationships could explain the observed, overall restricted, differences in morphology between the sticklebacks in this study, as most traits have diversified in common allometric trajectories. The observed differences in foraging and antipredation traits between the fish with a lagoon and freshwater genetic signature are likely a result of genetic or plastic adaptations toward brackish and freshwater environments.

Integrating freshwater wetland science into planning for Great Barrier Reef sustainability

Abstract The paper ‘Biodiversity values of remnant freshwater floodplain lagoons in agricultural catchments: evidence for fish of the Wet Tropics bioregion, northern Australia’, published in Aquatic Conservation: Marine and Freshwater Ecosystems in 2015, has contributed in several ways to the integration of freshwater wetland science within new catchment management policies and practices for Great Barrier Reef (GBR) sustainability. The Tully–Murray biodiversity study developed novel protocols to sample larval, juvenile, and adult fish life‐history stages in floodplain lagoons using a combination of boat‐based backpack electrofishing and fyke netting. In addition, hydrological and hydrodynamic models were applied in a completely new way to quantify the timing, extent, and duration of water connectivity across floodplain streams, cane drains, and wetlands. Combining the two novel approaches enabled an analysis of lagoon fish assemblage patterns in relation to environmental gradients, especially floodplain hydrology, connectivity patterns, and measures related to agricultural land use. In demonstrating the importance of different levels of connectivity for different biodiversity outcomes in freshwater floodplain lagoons of the Tully–Murray catchment, the subject paper established that floodplain connectivity needs to be taken into consideration in wetland management practices. The timing of the subject publication was fortuitous. It coincided with the preparation of the evidence‐based 2017 Scientific Consensus Statement on land‐based water quality impacts on the GBR. As one of the few freshwater wetland ecology publications for the catchments of the GBR at that time, this paper played an important role in demonstrating freshwater wetland values, fish conservation options, and management imperatives to sustain wetland ecological health and services in GBR catchments. By advancing the understanding of factors driving biodiversity patterns, and the importance of connectivity and ecohydrological processes in freshwater floodplain wetlands of the GBR catchment, the Tully–Murray study helped to drive new policy directives for the protection and restoration of catchment, floodplain, and estuary functions, and connectivity, now embedded in the Reef 2050 Long‐Term Sustainability Plan 2018, an overarching strategy for managing the GBR over the next 35 years, and complementary Queensland environmental legislation.

Lagoon Resident Fish Species of Conservation Interest According to the Habitat Directive (92/43/CEE): A Review on Their Potential Use as Ecological Indicator Species

Transitional waters are fragile ecosystems with high ecological, social and economic values, that undergo numerous threats. According to the information provided by European Member States in the framework of the European Directive 92/43/EEC (Habitat Directive), the main threat to these ecosystems is represented by morphological and hydrological changes. The present work focuses on six lagoon fish species included in the Habitat Directive annex II (species requiring conservation measures: Aphanius fasciatus, A. iberus, Knipowitschia panizzae, Ninnigobius canestrinii, Valencia hispanica and V. letourneuxi) that spend their entire life cycle in the Mediterranean priority habitat 1150* “Coastal lagoons”. The overview of the current scientific literature allowed us to highlight how the presence and abundance of these species may provide important indications on the conservation status of coastal lagoon habitats. In fact, their occurrence, distribution and biology depend on the presence of peculiar structures, such as salt marshes, small channels, isolated pools and oligohaline areas. Coastal lagoon fragmentation and habitat loss have led to a significant reduction in genetic diversity or local population extinction. Although Aphanius and gobies have been shown to survive in eutrophic environments, it is clear that they cannot complete their life cycle without salt marshes (mainly Aphanius) and wetland areas (mainly gobies).

The Tale of a Disappearing Lagoon: A Habitat Mapping and Ecological Assessment of Fosu Lagoon, Ghana

Coastal regions of Ghana are primarily engaged in sea and lagoon fishing. Like many lagoons in Ghana, Fosu lagoon is a major source of livelihood for its surrounding communities. However, the lagoon and its associated marsh vegetation is under serious threat from human-induced interference. Due to this, the lagoon is considered as one of the most polluted lagoons in Ghana. Also, studies reveal that a major conservation challenge is the lack of inventory for the lagoon’s associated vegetation. Hence, the research was to map and assess the lagoon’s habitat and identify threats to the lagoon. In achieving the research objectives, remote sensing and GIS technique were used to effectively map the lagoon and the catchment area. The result indicated that the Fosu lagoon is characterized by a massive decline in lagoon size and the vegetation cover. Thus, the standing water has declined by 50.2 acres from 1970 to 2017 to physical development and weeds. Also, it was evident in the result that the lagoon’s vegetation is now fragmented into six various vegetation types and the weeds in the lagoon make approximately one-third of the lagoon’s vegetation cover. Also, adding to the threat of the lagoon were high levels of plastic waste and metal pollution. Hence, if current trend continues, the possibility of further degradation is very high. The main impact of this research was to provide evidence to the gradual disappearance of the Fosu lagoon.

Terrestrial-marine continuum of sedimentary natural organic matter in a mid-latitude estuarine system

Humic acids (HA) have several environmental roles, but are particularly important in aquatic environments, being recognized as redox active natural organic matter (NOM) components. We examined NOM in recent sediments of a low-energy coastal environment which is free from inputs of dissolved terrestrial HA as their solubility is suppressed by bonding with Ca2+ ions. Our aim is to investigate the contribution of autochthonous versus terrestrial C sources to HA and their fractions along a river-coastal lagoon transect. Surface sediments were collected along the Aussa River (R), in the central basin of the Marano and Grado Lagoon (L) and within a secluded lagoon fish farm (FF). Extractable NOM components were obtained by extracting sediments first with 0.5 M NaOH (free NOM) and then with 0.1 M NaOH plus 0.1 M Na4P2O7 (bound NOM). Extracts were separated into non-humic and humic fractions by solid phase chromatography. Organic carbon (Corg), total nitrogen (Ntot), δ13C, and δ15N were determined with an Isotope Ratio Mass Spectrometer (Thermo Scientific Delta V Advantage) coupled with an Elemental Analyzer (Costech Instruments Elemental Combustion System). Fourier-transform infrared (FTIR) spectra were recorded with a FT-IR100 PerkinElmer Spectrometer. UV-vis spectra were recorded at pH 7 by a Varian Cary Spectrophotometer. Both NOM and HA display typical traits of terrestrial origin in river sediments and of a more marine (algal) origin in lagoon and fish farm sediments. This trend is evident in free HA, whereas bound HA seem more influenced by terrestrial inputs. A larger proportion (60–70%) of non-humic C was extracted by NaOH in all samples. Bound HA differ from free HA for their C/N ratios, which are higher and vary within a much narrower range. The changes in HA’s 13C isotopic composition, FTIR spectra, and spectroscopic parameters (SUVA254, SR, and aromaticity) highlight a progressive mixing of terrestrial and marine substrates that either undergo in situ humification or are transported as materials sorbed onto suspended mineral particles. Our results highlight the existence of a complex, but continuous pattern of terrestrial and marine contributions to C sequestration and humification even in transitional environments where allochthonous humic C inputs are restricted due to insolubilization of humic substances by Ca2+. Along the examined transect, the NOM and free and bound HA appear well differentiated. Terrestrial inputs contribute to the bound HA fraction via transported mineral particles in all the samples, no matter the environment encountered.

Assessing the ecological status of an estuarine ecosystem: linking biodiversity and food-web indicators

During the last decades, the highly-anthropized Seine estuary has been impacted by modification of its habitats (building of a major extension of Le Havre harbour, i.e. Port2000) and a significant natural decrease in freshwater discharge. A Before/After analysis, using a toolbox of indicators, was applied to characterize the effects of both events on the estuarine ecosystem status. We selected from existing tool boxes several indicators derived from food web modelling or community composition data, such as biodiversity indicators, a guild-based index (i.e. Estuarine and Lagoon Fish Index ELFI) and ecological network analysis (ENA) indices. ENA and biodiversity indicators were applied on six spatial boxes describing the Seine estuary and its outlet. Results showed an increase in taxonomic and functional richness over time, mainly due to marinisation, and significant changes in food-web properties in relation to Port2000. ENA indices appeared as a promising method in ecological status assessment, especially for estuaries considered as inherently disturbed.

Fish as bioindicators of habitat degradation in coastal lagoons of Ghana

Abstract. Eugenia BB, Armah AK, Dankwa HR. 2018. Fish as bioindicators of habitat degradation in coastal lagoons of Ghana. Bonorowo Wetlands 2: 9-26. Lagoons habitat forms an integral part of the marine fishing industry and provides essential spawning and nursery grounds for many fishes. Fish act as biological indicators of water quality and changes by summarizing information regarding their environment. Two lagoons, Laloi and Oyibi in the and Greater Accra and Central Regions of Ghana were studied to determine the ecological status using the Estuarine Fish Community Index (EFCI). Metrics assigned were the species diversity, nursery function, trophic integrity, and species abundance and composition. Water samples were obtained at the riverine, middle, and seaward portions during both high and low tides at each site. Fisherfolks were hired to fish at each of the sites. There are no significant differences between sites as measured by diversity indices. Multivariate analysis showed a considerable similarity between sites regarding species composition. This study identified eighteen species, including both finfish and shellfish. Two most abundant species during the study was the flathead grey mullet (Mugil cephalus) and the black-chinned tilapia (Sarotherodon melanotheron). Mugil cephalus dominated catches in the Laloi lagoon, whereas Sarotherodon melanotheron were dominant in the Oyibi Lagoon. The most dominant species collected for the Laloi lagoon were S. melanotheron, Lutjanus fulgens, and Eucinostomus melanopterus. Caranx hippos, L. fulgens, and M. cephalus constituted a significant part of fishes caught in the Oyibi lagoon. The carangid, Caranx hippos contributed primarily of the biomass of fishes collected for both lagoons. In the rainy season, total fish abundance was higher than the dry season. Chlorophyll-a concentrations and condition factor of S. melanotheron were highest at both lagoons. Total organic carbon was high in the Oyibi lagoon; hence, the high numbers of S. melanotheron recorded. Tides were an essential factor affecting physicochemical parameters. Oyibi displayed a moderate site rating, suggesting that it was under mild stress with some stress factors identified were garbage dumping, defecation, land-use changes, and increased human pressure. Meanwhile, Laloi Lagoon had a poor site rating, suggesting that it was under severe stress. The principal strains identified were overfishing, garbage dumping, mangrove degradation, and increased human settlements along the sides of the lagoon. The multi-metric index described served an effective method which reflects the status of lagoon fish communities and the overall ecosystem conditions.

Analysis of three sampling methods of early life history of fish in marginal lagoons of southeastern Brazil

This work aimed to evaluate the capture success of early life stage fish using three sampling methods (hand net, plankton net, and quatrefoil light trap). The hand net presented better sampling efficiency in the studied lagoons, with the capture of 13 exclusive taxa. Young migratory species, such as Prochilodus argenteus, P. costatus and Salminus hilarii, were only collected in the hand net, suggesting its applicability and efficiency in studies of migratory species in nursery environments. On the other hand, the plankton net and quatrefoil light trap were less efficient related to the number of captured species. However, the latter method has captured a high abundance of Anchoviella vaillanti suggesting that this species is photoactive and that this method is highly selective. None of the methods used presented significant selectivity in the capture of individuals at specific stages of early development.

Heavy metals concentration and histopathological profile of some commercial fish species at Makoko Slum Neighbourhood Environment, Lagos, Nigeria

Potentially harmful substances such as pesticides, heavy metals, and hydro chemicals are often released into the aquatic environment. The objective of the present study was to assess the concentration of lead, copper, cadmium, chromium, and nickel in water samples from two different points (Mid-stream and downstream), also determine the levelsof Lead, Zinc, Manganese and copper in four commercially important fish species, Pseudotolithus senegalensis (croaker fish) and Ethmalosa fimbriata (bonga), Oreochromis mossambicus (Tilapia fish) and Bagrus bayad (silver catfish) from Makoko water body, Yaba, Lagos, Nigeria. Histopathological profile of the fish species selected was also examined. The results were compared to the World Health Organization (WHO) acceptable limit.The concentrations of the heavy metals were analyzed using Perkin Atomic Absorption Spectrophotometer (AAS). Pseudotholithus senegalensishad 3.01±0.02, 2.41±0.02, 3.48±0.01, 1.04±0.10 mg kg-1as the mean concentration of lead, zinc, manganese, and copper respectively, while E. fimbriatahad 1.06±0.02, 2.41±0.02, 4.14±0.01, 1.04±0.10 mg kg-1,O. mossambicushad 2.09±0.02, 3.11±0.04, 2.48±0.02, 0.62±0.01 mg kg-1and B. bayadhad 1.53±0.12, 3.61±0.05, 2.44±0.03, 0.66±0.01 mg kg-1 as the mean concentration of these metals in the tissues of these fishes. The concentrations of heavy metals were higher in the gills compared to other organs. The mean concentration of each heavy metal were varied significantly (p0.05) depending on the species of fish. In the histological analysis of the tissues, there was vacuolation of hepatocytes, inflammation, and necrosis. In the muscle, there was a mild lesion, necrosis, inflammation, and cellular degenerations. But the level of tissue and organ degeneration is more severe in the gills. The study showed that some levels of these metals were within the permissible recommended allowed limit for human consumption. It is concluded that Makoko Lagoon water body and fishes are heavily contaminated with heavy metals.

24th NATIONAL SCIENTIFIC PRACTICAL CONFERENCE “NATURAL SCIENCE EDUCATION IN A COMPREHENSIVE SCHOOL – 2018”: CONFERENCE REVIEW

Having already become traditional, scientific practical conference “Natural science education in a comprehensive school – 2018” took place in Šilutė, a beautiful Pajūris lowland city. On the first conference day, plenary reports and two section work took place. It was discussed about the exceptional geological exhibit importance to non-formal natural science education and about Lithuanian and Latvian student attitude to natural science disciplines and mathematics. Traditionally, methodological natural science education questions were discussed. One plenary report was made remotely. Dr. Solange W. Locatelli from Brazilian Federal ABC university shared her personal experience applying metacognitive strategies in chemistry teaching. Most conference reports were presented in the form of articles and published in the conference proceedings. One can find full texts in the database at: http://oaji.net/journal-archive-stats.html?number=1984&year=2018&issue=12477 On the initiative of Šilutė district municipality, a cognitive conference participants’ boat trip down the Nemunas river to Kuršių lagoon was organised. Conference participants had a unique possibility to get acquainted with the lagoon district, to see off the Sun, and also to taste traditional lagoon fish soup. On the second conference day, the reports were also presented. It was discussed about teaching based on researching. The main report idea was educational activity object selection and pedagogical scenarios preparation. Pilot empirical research results were presented. Natural science education organisation and improvement in a primary school was discussed. The carried-out research allows stating, that primary school teacher professional preparation in a natural education sphere remains actual. Practical work organisation is considered the most appropriate activity. The teachers try the least to satisfy / to take into consideration individual students’ differences. Though teachers are inclined to demonstrate various experiments, research activity is not dominating. Natural science education “journey” continues. 25-th conference will take place on 26-27 April 2019 in Kupiškis Povilas Matulionis progymnasium. So, from Pajūris lowland we travel to Kupiškis, which is in the outskirts of eastern middle Lithuania lowland and in which the Kupa river flows through the centre of the city. Key words: national conference, science education, science and technological education movement.