Fish Nursery Research Articles

Chatting behind the reef: Fish bioacoustic diversity of tropical back-reefs in Fiji, South Pacific.

Back-reef habitats are important and fragile transition zones acting as nurseries for many coral reef fishes. In this framework, Passive Acoustic Monitoring (PAM) can be an important tool to evaluate the diversity and dynamics of sonic fish community. Here, we investigated the diversity, spatial and diel dynamics of fish sounds in back-reef habitats at Makogai Island in Fiji, South Pacific. Synchronized underwater recorders were deployed in 4 bays collecting data for about 4 days. The abundance of 12 different sub-categories of fish sounds were quantified. Signals were acoustically characterized and the level of discrimination between the sub-categories was evaluated by Discrimination Function Analysis. Generalized Additive Models showed that the abundance of signals was related to the bay and the hour. Moreover, the Shannon Diversity and Equitability Indices were calculated using acoustic and visual census data to describe fish biodiversity of each bay. The two bays with greater biodiversity based on visual census also showed a greater acoustic diversity at dawn and night. Our results highlight the importance of PAM to reveal the diversity of fish community in back-reef habitats, providing a baseline to understand future changes in these crucial environments.

Evaluating the Impact of Diverse Types of Green Vegetables on Snakehead Fish (Channa Striata) Nursery through an Eco-Friendly Aquaponic Approach

Evaluating the Impact of Diverse Types of Green Vegetables on Snakehead Fish (Channa Striata) Nursery through an Eco-Friendly Aquaponic Approach

Beyond annual metrics: Linking seasonal population dynamics to vertical oyster reef growth.

Oysters are ecosystem engineering species building reef-like biogenic structures in temperate shallow water environments, serving as biodiversity hotspots. Recently, also their ecosystem services such as fish nursery, pollutants sink and self-sustaining coastal protection mechanisms came into a research focus. In light of accelerated sea level rise and increasing environmental dynamics, a determination of vertical growth rates of these biosedimentary structures is paramount in assessing their resilience. This study embarked on a comprehensive survey of seasonal vertical reef growth rates using terrestrial laser scanning and related population dynamics of two intertidal reefs built by the non-native oyster Magallana gigas in the Wadden Sea. We quantified median reef growth at 19.8 mm yr-1 for the Kaiserbalje reef and 17.5 mm yr-1 for the Nordland reef. Additionally, we tested the hypothesis that the seasonal variations in reef growth rates correspond to the local population dynamics, mainly the parameters of shell length and abundance which mirror delayed effects from previous spawning events. Shell growth rates were 0.03-0.06 mm d-1 in winter and 0.10-0.16 mm d-1 in summer, mean oyster abundance from autumn 2019 to spring 2022 was 627 ± 43 ind. m-2 and 338 ± 87 ind. m-2 at the Kaiserbalje and Nordland reefs respectively. Minor reef growth in the topmost reef area reflects an emerging equilibrium of the vertical reef position to actual sea level. Our findings are in accordance with growth of natural Crassostrea virginica reefs on the US East Coast, indicating potential resilience to actual and predicted sea level rise scenarios. Moreover, understanding local hydro-morphodynamic feedback linked to sea level rise will be vital in predicting the three-dimensional stability of these biosedimentary structures and habitats.

The potential fish provisioning services of vegetated and unvegetated habitat in a lagoon nursery

The potential fish provisioning services of the Ria Formosa lagoon (Portugal) were calculated for single cohorts of 7 commercially fished species, based on densities of juveniles sampled with beach seines on a monthly basis over a 17-month period at 41 locations. The potential maximum yield per recruit (F0.1 criteria) was calculated for vegetated (V) and unvegetated (UV) habitat for low and high natural mortality values. Vegetated habitat enhanced yield (g m−2) of 5 of the 7 species, with the greatest enhancement for the herbivore Sarpa salpa (137 and 150 fold for low and high M). At F0.1, the calculated total potential yield of the 7 cohorts was 463 tons (low M) and 333 tons (high M), worth EUR 5,649,084 and 3,651,881, respectively. Mean annual landings of the 7 species from 1997 to 2017 ranged from 407 to 577 tons, with a mean of 495 tons (s.e. = 11.1), highlighting the importance of the lagoon nursery as a major source of recruits for local small-scale coastal fisheries. The methodology used here is the first to calculate the potential maximum yield and the corresponding fishing mortality (F0.1) for single cohorts and for different habitats within an important fish nursery. It provides more realistic values of potential fish provisioning services and economic contribution to local fisheries than studies that do not consider fishing mortality.

Investigation of the causes and mechanisms of hypoxia in the central Bohai Sea in the summer of 2022

The deep-water area in the central Bohai Sea (BS) serves as a spawning ground and nursery for fish, shrimp, and crabs. Frequent hypoxia will affect the ecological environment in the central BS. Data from an on-site investigation of the central BS in the spring and summer of 2022 were used to analyze the relevant factors generating the occurrence of hypoxia in the central BS through the eutrophication index E, apparent oxygen consumption (AOU), and Spearman correlation. The hypoxia area was largely distributed in the study area's deep water section, and stratification was the main cause of hypoxia at the bottom. Organic matter mineralization, degradation, and biological respiration further exacerbated the hypoxia. In the summer of 2022, temperature stratification was the dominant factor influencing hypoxia.

Multi‐year monitoring shows higher species richness and diversity of fish assemblages in a Danish seagrass meadow as compared to neighbouring non‐vegetated areas

AbstractSeagrass meadows provide an important nursery and feeding habitat for fish, globally. However, limited data exist on how these vegetated coastal ecosystems affect local fish stocks over longer time periods. By means of beach seine hauling with a bio‐monitoring seine net, we collected fish data in Kronborg Bay (Denmark) over 4 years. The bay contains both vegetated and bare sediment areas in close proximity to Kronborg Castle in Elsinore and is part of the Øresund strait; a dynamic marine environment linking the Baltic Sea with the inner Danish waters (Kattegat). We investigated the biodiversity and fish abundance in a healthy seagrass meadow and compared it with a bare adjacent sediment area. We show that seagrass is important for fish species like the Atlantic cod, the two‐spotted goby, and the broadnosed pipefish. The seagrass meadow harboured more fish species and higher biodiversity, while the number of individuals was higher in the adjacent bare sediment area as a result of high abundances of lesser sand eel. Pilou's evenness and the Shannon‐Wiener index showed 2–4‐fold higher biodiversity in the seagrass meadow. The seagrass meadow harboured about 35% more fish species than the bare adjacent sediment. The Atlantic cod was almost entirely found in the seagrass meadow, while lesser sand eel that showed an overall increase in abundance in both habitats, represented the largest proportion of the total number of fish individuals (up to about 60%) and was mostly found on the bare adjacent sediment. Species abundance was analysed for changes over time, where, for example the European plaice showed an increase in abundance over the 4‐year period of investigation. Seagrass meadows can thus be very important for the Atlantic cod population in the Øresund strait and generally for local fish productivity, abundance and diversity.

Development of gadgets and systems in plastic for use in freshwater aquaculture

The usage of plastics has transformed the agricultural production sector and has great impactin improving the overall scenario in all production systems including fisheries and aquaculture.Nylon fishnets, components of RAS, aquaponics and biofloc (BF)systems, plastic pipe framed nylon net cages, pen culture in water locked areas, etc. are some of the important uses of plastics in aquaculture. The AICRP on PEASEM, ICAR-CIFA, Bhubaneswar Centre is working since its inception in 1988 and contributed several plasticulture technologies and products for the development of aquaculture systems and processes (APA/CIFA 1988-2005; Mohapatra et.al., 2003, 2011 and 2016). The design and fabrication of the plastic gadgets and systems have been done considering the biological requirements of the aquaculture. The developed technologies are fully or partially adopted and accepted by the farming communities of the country. The paper presents some of the developed gadgets and systems that are presently in use in aquaculture in the country. Those are portable FRP carp hatchery having capacity of 1.0-1.2 million spawn production per cycle; portable FRP magur hatchery for incubation of 50,000 eggs per cycle; portable FRP pabda hatchery for production of 25,000-30,000 early fry per operation; different types of fixed and floating cages; live fish transportation tank of 1200l capacity which can be transported in a jeep trailer, power trailer or trolley; FRP silos of different sizes for fish rearing; feeders of different types such as demand, semiautomatic and automatic for fish feeding; plastic covered ponds for raising fishes in winter season; floating nursery for fish seed and aquaponics.. KEYWORDS :Modern farming Technique, Gedgets Plastic, Aquaculture

Spatio-Temporal Dynamics of Larval Fish Assemblage in the Nakdong River Estuary, South Korea

Estuaries are crucial fish nursery habitats owing to their high productivity and the presence of various microhabitats for the early development of aquatic organisms. This study investigated the temporal and spatial patterns of the species composition and abundance of larval fish assemblages in the Nakdong River estuary, South Korea, through bi-monthly sampling in the inner and outer estuaries. Fifty-five larval taxa were collected, and the larval fish assemblages were dominated by a few species. Engraulis japonicus (28.8%) was the most abundant, followed by Gobiidae sp.1 (22.6%), Clupea pallasii (13.9%), and Omobranchus sp. (6.1%). The species richness, abundance, and diversity tended to be higher during the warm season in the inner estuary. Multivariate analyses revealed that the structures of larval fish assemblages were significantly influenced by the season and site. Spatial and seasonal changes in larval fish assemblages resulted from the different occurrence patterns of common fish larvae in relation to water temperature and salinity. Among the predominant fish larvae, E. japonicus was captured more frequently in more saline outer estuaries during the warm season, whereas Gobiidae sp.1 and C. pallasii were more abundant in less saline inner estuaries during the warm and cold seasons, respectively. The results of this study improve our understanding of larval biodiversity in estuarine habitats in relation to environmental modification and contribute to the evaluation of nursery functions in the Nakdong River estuary.

A proposal for new genotoxic and cytotoxic endpoints to assess chemical effects on the red algae Ceramium tenuicorne.

Macroalgae provide key contributions to aquatic ecosystems, including their role as primary producers and the provision of biotopes for marine organisms, fish spawning, and fish nurseries. The aim of this study was to evaluate the feasibility of a micronucleus test and a comet assay in Ceramium tenuicorne, a red macroalga. This alga is widely distributed in marine ecosystems and brackish waters, and is therefore a potential bioindicator of the effects of anthropogenic pollution in these ecosystems. Unfortunately, the two genotoxicity tests evaluated were not suitable for this alga because the nuclei are generally very small (between 2 and 10µm), are variable in size, and there may be several nuclei in each cell (between 1 and 5 in our observations). However, the present study allowed us to define conditions for observing these algal cells and optimizing the choice of DNA dye (orcein), cell fixation solution (Carnoy's solution), and hydrolysis step (HCl, 1200mmol/L solution for 1min). This research allowed us to propose two genotoxicity and cytotoxicity endpoints for assessing chemical effects on the algal cells: counting of nuclei in cortical cell areas, and the frequency of axial cells in mitosis. These two criteria were measured after exposing C. tenuicorne to two reference substances: cadmium chloride and maleic hydrazide, and we highlight the effects from 1 × 10-5M of CdCl2 and 5 × 10-5M of maleic hydrazide.

Benchmarking fish biodiversity of seaports with eDNA and nearby marine reserves

AbstractCoastal areas offer a diversity of habitats providing refugia and nursery for fish, promoting their biodiversity and associated contributions to people. Yet, natural coastlines are replaced by artificial infrastructures such as seaports and the influence of this artificialization on fish biodiversity remains poorly known. Here, we assessed fish biodiversity indicators using environmental DNA metabarcoding inside seaports and adjacent natural habitats including no‐take marine reserves. We found that species assemblages within seaports were primarily influenced by their area and habitat. We detected a similar species richness in seaports and reserves during lockdown, but seaports host more threatened species than natural habitats. Yet, species turnover between seaports was lower than between natural areas, reflecting biotic homogenization. Seaport managers should consider that complexifying artificial infrastructures could increase habitat diversity and coastal fish biodiversity. Our study illustrates that eDNA‐based indicators can be integrated in management and policy applications toward greener marine artificial infrastructures.

Cross-habitat utilization of fish in a tropical deltaic system as a function of climate variability and body size: Are mangroves fish nurseries in a tropical delta?

The temporal variability of fish habitat utilization is poorly understood in tropical deltaic systems due to high water turbidity, which limits visual censuses, and to the lack of long-term data incorporating climate variability events. We aimed to assess the influence of body size and El Niño Southern Oscillation (ENSO) variability on the cross-habitat utilization rate of 14 fish species of commercial relevance in the Ciénaga Grande de Santa Marta (CGSM). We estimated the utilization of mangroves and coastal lagoons based on relative catch frequencies from encircling gillnets used within a long-term catch monitoring program, and then tested for significant changes in each species' habitat utilization as a function of body size and climate variability. Six species showed a high dependence on mangroves and four on coastal lagoons for most body size classes (including juveniles) and ENSO conditions. One species (Elops smithi) showed a high utilization of mangroves in some ENSO phases and body size classes, while three species showed a high utilization of both mangroves and coastal lagoons. Mangrove utilization by six species (Megalops atlanticus, E. smithi, Centropomus undecimalis, Mugil incilis, Mugil liza, and Ariopsis canteri) increased in larger body sizes at low depths, which usually occurs under dry ENSO conditions, when predatory risk is higher in coastal lagoons. Another species (Caquetaia kraussi) increased its mangrove utilization from the body size at which its feeding habits change. Mangroves and coastal lagoons are important nurseries and habitats for adults of the main commercial fish species in the CGSM. Seascape habitats and fringe/riverine mangroves must be conserved in tropical deltas to promote not only nurseries but also fish lifecycles.

Integrating fish nursery ground conservation with sustainable resource use: The case of Trichiurus japonicus in the East China Sea

Abstract Sustainable fisheries management seeks to balance fisheries' conservation with fishers' economic well‐being. Marine protected areas are increasingly used as a component of management frameworks to improve the resilience of, or maintain, marine resources. However, any spatial management measures need to consider the seasonal distribution of key species at key life stages, such as the recruitment stage. Trichiurus japonicus (hairtail) is the highest yielding single fish species in China, but it is showing signs of miniaturization and early maturity, which are indicators of overfishing. Thus, it is a suitable model species for studies aiming to find a solution to the challenge of balancing fishing activities with resource protection. The potentially important seasonal nursery grounds of T. japonicus in the East China Sea were identified using a model combining data for the variability in abundance and the probability of occurrence of T. japonicus recruits. Based on fishery‐independent survey data, a Bayesian hierarchical species distribution model revealed that the locations and sizes of core nursery grounds of T. japonicus varied seasonally and that the main drivers were depth, sea bottom temperature and sea bottom salinity. The possible seasonal interactions between fishing effort and nursery grounds at different levels of importance were evaluated by analysing the spatial overlap between fishery hot spots and T. japonicus core nursery grounds. The results showed that the proportion of overlap was highest in spring and lowest in summer. These findings highlight the urgent need to develop fleet‐adapted management measures for different levels of overlap and suggest that the eastern and southern areas of the East China Sea hairtail national aquatic germplasm resources conservation zone (TCZ) should be included in conservation planning.

Efforts to Improve the Welfare of Ornamental Fish Farmers in Kalipaten Village Through the Implementation of LoRaWAN-Based IoT Technology

The ornamental fish business is currently one of the popular businesses in the community. The relatively fast reproduction cycle, around 0.5 – 1.5 months, with a relatively high selling price, makes this ornamental fish business much in demand by the public. The maximum utilization of technology will help MSMEs in increasing their income. This service activity aims to build a LoRaWAN-based IoT system for ornamental fish farming along with a mobile-based ornamental fish monitoring application to help manage ornamental fish livestock, which ultimately has an impact on improving the quality of ornamental fish and the income of CV Home Aquafish partners. The method utilizes a service-learning approach through stages: Identify, design, and build a LoRaWAN-based IoT and mobile-based monitoring system, implementing, mentoring, and measuring the effectiveness of the LoRaWAN device in improving the quality of ornamental fish and the income of CV Home Aquafish partners. As a result, LoRaWAN can effectively help minimize mortality in ornamental fish seedlings so that the quality of the fish is maintained. The income of CV Home Aquafish's ornamental fish nursery partners in Kalipaten Village, Gading Serpong, Tangerang also increases.

Brief floodplain inundation provides growth and survival benefits to a young-of-year fish in an intermittent river threatened by water development

Riverine floodplains are highly productive habitats that often act as nurseries for fish but are threatened by flow regulation. The Fitzroy River in northern Australia is facing development, but uncertainty exists regarding the extent to which floodplain habitats deliver benefits to fish, particularly given the brevity of seasonal floodplain inundation. We investigated the growth rate of young-of-year bony bream (Nematalosa erebi) in main channel and ephemeral floodplain habitats using age derived from otolith daily increments. We also investigated potential mechanisms influencing growth and modelled the consequences of differential growth rate on survival. Our results revealed higher growth occurred exclusively on the floodplain and that zooplankton biomass was the best predictor of growth rate. Modelling indicated that elevated growth rate in high-growth floodplain pools (top 25th percentile) could translate into substantial increases in survivorship. The positive effect of zooplankton biomass on growth was moderated under highly turbid conditions. Temperature had a minor influence on growth, and only in floodplain habitats. Our results indicate ephemeral floodplain habitats can deliver substantial growth and survival benefits to young-of-year fish even when floodplain inundation is brief. This study highlights the need to ensure that water policy safeguards floodplain habitats due to their important ecological role.

DNA metabarcoding reveals the diet of the invasive fish Oreochromis mossambicus in mangroves of São Tomé Island (Gulf of Guinea)

AbstractInvasive species can trigger profound effects on recipient ecosystems, namely through the food web. Despite being recognized as one of the worst invasive species, little is known about the feeding ecology of the Mozambique tilapia Oreochromis mossambicus. To understand how this invasive species might impact food webs, we applied metabarcoding to analyze its diet’s composition in two African mangroves, in the Obô Natural Park in the oceanic island of São Tomé. Given the particular importance of mangroves as fish nurseries, we specifically aimed to determine if this invader might predate on other fish species. However, we found that tilapia were mostly phytoplanktivorous and indication on predation of other fish was very limited. Instead, due to their local high densities, tilapia may impact basal trophic levels and nutrient availability with the potential to cascade through the food web by means of bottom-up disruption. In addition, we recorded important changes in the taxonomic composition of the diet, linked to locations and life stages, suggesting that its opportunistic feeding associated with its aggressive territorial behavior may result in resource competition with native species with which it has overlapping dietary niches.

Spatio-temporal dynamics of habitat use by fish in a restored alluvial floodplain over two decades

River floodplain channels can serve as reproduction, nursery or refuge areas for fish. Although the complementary use of floodplain and main channels is known, few studies attempted to quantify this use and even fewer analysed its controlling factors. The objectives of this study are (1) to describe the spatio-temporal use of floodplain habitats and to identify their roles as complementary habitats for fish and (2) to analyse how abiotic variations and their modifications under restoration impact habitat use by fish. To meet these objectives, we analysed (Principal Components Analysis and Coinertia Analysis) multi-site data collected over 20 years in eight main channels and 23 floodplain channels of eight restored sectors of the French Rhône River. Results show that habitat use by fish is mainly related to spatial effects, with 37 % of within-sector variance in taxonomic assemblages explained by the stations. As expected, rheophilic species were more abundant in lotic stations and limnophilic species in lentic ones. In addition, we identified an euryecious guild, grouping young of the year taxa (roach, gudgeon, chub, bleak) that used all types of habitats and particularly lentic floodplain channels with short life-span. Temporal effects (with ~10 % of the variance explained by years) combine (1) the effect of restoration, that increased the diversity of fish assemblages across the floodplain, with stronger changes in floodplain channels whose connectivity regime was modified, (2) the effect of high flows on fish habitat use, that reinforces the nursery and refuge functions of floodplain channels. Our results demonstrate the importance of restoring the diversity of habitats and connectivity because floodplain habitats have complementary functions for fish. Furthermore, our results also suggest to account for temporal variations in order to better estimate the potential effects of restoration on river and their floodplains.

The Authority of Lampung Provincial Government in Managing Fisheries Resources in Era of Regional Autonomy

The global COVID-19 outbreak has had a major impact on the marine and fisheries industry in Indonesia. This is also felt by fishermen in Lampung Province with the decline in demand for fishery products in the domestic and international markets in Lampung Province. The overall decline in the fisheries production cycle is influenced by the decline in demand from consumers. The local government has an important role to help restore the condition. The problem in this research is how the authority of the local government of Lampung Province in the management of fisheries resources in the era of regional autonomy and how the efforts of the marine and fisheries office of Lampung Province in an effort to achieve fisheries production in the era of regional autonomy. The research method used is normative research with statute approach. The results of this study are in accordance with the Governor's Regulation on the determination of the main tasks and functions of the Lampung Province Maritime and Fisheries Service as an implementing element of local government in the field of marine and fisheries led by a Head of Service who is responsible to the Governor. he goal is to implement the commitment of the Governor and Deputy Governor elected in 2019-2024 on marine and the Berjaya Fishermen Program to prioritize the welfare of the fishing industry, especially fishermen and their families. The Lampung Provincial Maritime and Fisheries Service provides solutions in the form of feed assistance in collaboration with Lampung University, fish nurseries and distribution in four districts and cities as well as Mobilizing registration and licensing to increase the capacity of fishermen and facilitate licensing and shipping documentation.

OPTIMALIZATION AND SOCIALIZATION OF INTERNET-BASED AQUACULTURE MEDIA CONDITION MONITORING TECHNOLOGY, ARSENIK 2

Indonesia's geographical condition, as a maritime country, has a wealth of natural resources in the form of water, which has the potential to support the economy in the aquaculture sector. One of them is the cultivation of freshwater fish ponds as has been carried out by the Maju Rukun Community Group (PokMas) in Ngerong Village, Pasuruan. Lack of equipment and knowledge in monitoring pond water conditions, resulting in problems with the fish nursery process. This is because water is a living medium for aquatic organisms, thus determining the survival of cultivated fish. Therefore, community service activities were held in the form of implementing an appropriate technology device "Arsenik version 2" and a mobile application that can be downloaded on Android to support water quality monitoring in aquaculture. In addition, socialization, training, and seminars regarding parameters of good pond water quality for fish farming were also provided to the Maju Rukun PokMas and the local community. Based on the positive response from the community, the implementation of the Arsenic device version 2 is considered very helpful in terms of monitoring the condition of pond water quality because it has informative parameter values and an easy presentation to understand so that the public can maintain the health of aquatic media for the aquaculture ecosystem in it.

Essential and toxic elements in juvenile migratory commercial fish species in the Paraná River alluvial valley (South America): an approach for aquatic environmental monitoring.

The Paraná River is the sixth largest in the world, and the lower section of the river is one of the largest and most productive floodplain wetlands in South America. The alluvial plain is an important habitat for nursery and feeding areas for commercial fish; however, it has been heavily anthropized due to industries, agricultural activities, and the growth and expansion of metropolitan areas. The aim of this study was to determine element accumulation (As, Cd, Cr, Cu, Fe, Mn, Pb, and Zn) in young-of-the-year fish muscle from a floodplain lagoon of the lower Paraná River (Argentina) during summer and winter seasons, in relation with abiotic matrices (water and sediment). Four commercial fish species were assessed: sábalo (Prochilodus lineatus), boga (Megaleporinus obtusidens), dorado (Salminus brasiliensis), and pirapitá (Brycon orbignyanus). The concentrations of eight elements were detected by quadrupole inductively coupled plasma mass spectrometry. In water samples, Cd, Cr, Mn, Fe, and Zn levels were under the permissible limits for aquatic biota protection in both seasons, except for Pb (> 1 μg L-1) and Cu (> 2 μg L-1). In sediment, the average concentrations of all elements were under the limits set by national and international regulatory authorities. Differences in elemental concentrations between species and seasons were found. In general, the levels of elements in water were higher in summer than in winter, while in sediment, the lowest concentrations of elements were detected during the summer. The order of element concentration in fish muscle was Cd (0.01-0.04 μg g-1) < As (0.02-0.16 μg g-1) < Pb (0.03-0.23 μg g-1) < Mn (0.77-4.32 μg g-1) < Cu (1.01-4.07 μg g-1) < Cr (1.09-4.30 μg g-1) < Zn (15.8-31.7 μg g -1) < Fe (12.6-49.7 μg g-1). The accumulation assessment showed that the four fish species significantly accumulate Cr, Cu and Zn, and As and Zn from water and sediment, respectively. The correlation analysis showed a relationship between fish size and As, Cr, Cu, Fe, Mn, and Zn concentrations. Similarly, the highest values of element concentrations in muscle were detected during the summer when the fishes are early juveniles. The level of As, Cd, and Pb detected in B. orbignyanus, M. obtusidens, and P. lineatus juveniles suggested that these species had the potential to be used as biomarkers for assessing accumulation of toxic elements in the environment. Also, this study reveals that the accumulation patterns differ between size and fish species, which should be a considered insight at the moment of selecting a bioindicator to monitor pollution in the ecosystem.

Artificial fish nurseries can restore certain nursery characteristics in marine urban habitats

Port areas are subjected to multiple anthropic pressures that directly impact residing marine communities and deprive them of most of their essential ecological functions. Several global projects aim to rehabilitate certain ecosystem functions in port areas, such as a fish nursery function, by installing artificial fish nurseries (AFN). In theory, AFNs increase fish biodiversity and juvenile fish abundance in port areas, but studies on this subject remain scarce. Thus, the present study aimed to examine whether the use of such AFNs could restore part of the nursery function of natural habitats by increasing fish and juvenile abundance, and by decreasing predation intensity compared to bare docks. Two years of monitoring on AFNs showed they hosted 2.1 times more fish than on control docks and up to 2.4 more fish juveniles. Fish community structures were influenced by both treatment (AFN and Control) and year of monitoring. In general, AFNs hosted a greater taxonomic diversity of fish than controls. The predation intensity around these structures was significantly lower in the AFNs than in controls. Part of the definition of a fish nursery was thus verified, indicating that AFNs might be an effective restoration tool. However, we also noted that total fish abundance and Young of the Year (YOY) abundance decreased in controls, possibly due to a concentration effect. Further detailed monitoring is necessary to distinguish between these effects.