Distribution Of Ichthyoplankton Research Articles

Microplastic and ichthyoplankton in the Ukrainian waters of the Black Sea

The ability of planktonic and neustonic organisms to feed on microplastics and subsequently transfer it through the marine food web has been studied extensively. However, there are no studies on microplastic in the Northwestern Black Sea. The present study assesses the diversity and spatial distribution of microplastics and ichthyoplankton in two surface layers: 0–5 cm (neuston surface layer; NL) and 5–20 cm (hyponeuston layer; HL). The sampling was undertaken in June 2020 – October 2021 in the coastal (CW) and open (OW) waters of the Northwestern Black Sea. Microplastics was observed at all studied sites and was composed of fibres (75 %) and fragments (25 %). Black and red fibres were the most abundant type of fibre, and black particles dominated the fragments. Four types of polymers were identified by Raman spectroscopy: polyethylene, polyester, polyurethane, polypropylene. The concentration of microplastics near the coast significantly exceeded that of open waters; the average microplastics concentration in the CW reached 136±74 (±SE) and 46±30 particles.m-3 in the NL and HL, respectively, whereas it reached 18±3 and 2±0.8 particles.m-3 in the NL and HL of the OW, respectively. In the NL, ichthyoplankton was found only at 31 % of the sites, and at only 24 % of sites in the HL. In total, 6 species of fish were recorded. The most abundant species was the European anchovy, one of the main commercial species in the Black Sea. The ratio of microplastics to ichthyoplankton was 0.34 (or 1:2.87) for both layers, where ichthyoplankton was present. When considering all studied sites, the ratio of microplastics to ichthyoplankton was 1.07 (or 1:0.93). As ichthyoplankton is an ephemeral component of the neuston community, but microplastics is omnipresent, we may consider that comparable densities of microplastics:ichthyoplankton favour their interrelation, negative effect, and transport through the food web.

Features of the Distribution of Black Sea Ichthyoplankton in Conditions of Activation of Atmospheric Processes in the Summer Hydrological Season of 2021

Features of the Distribution of Black Sea Ichthyoplankton in Conditions of Activation of Atmospheric Processes in the Summer Hydrological Season of 2021

Ichthyoplankton dynamics in the Brazilian Pantanal: Contribution of an important tributary and maintenance of connectivity

AbstractIn order to investigate the reproductive dynamics of the ichthyofauna in the Brazilian Pantanal, this study examines the spatial and temporal distribution of ichthyoplankton, taxonomic composition, and its correlation with environmental factors within one of the most important sub‐basins, the Taquari River. Egg and larvae collections were conducted at 11 sampling points between October and March of 2017/2018 and 2018/2019. Significant differences were observed between collection points, months, and years, with higher ichthyoplankton densities in the Coxim and Taquari rivers, particularly between November and January. Twenty‐eight genera and/or species of fish were identified, including 10 long‐distance migratory species. Egg density showed a negative correlation with water temperature and rainfall. For larvae, water transparency and rainfall were both significant, negatively influencing larval abundance. However, different species tend to occur in environments with distinct abiotic qualities. Yolk‐sac, preflexion, and flexion larval development stages were distributed throughout the sub‐basin, especially near the Pantanal. Considering the data and analyses presented in this study, the importance of connectivity between these environments, specifically between the plateau and Pantanal, is evident, highlighting the significance of the entire sub‐basin for fish reproductive processes. Therefore, research focusing on the ecological processes influencing the distribution of ichthyoplankton offers valuable insights for ecosystem conservation and aids in effective environmental management.

The influence of the Black Sea rim current and the coastal quasi-stationary anticyclonic Eddie on the distribution of ichthyoplankton and jellyfish

This article describes the Black Sea quasi-stationary coastal anticyclonic eddy (CAE), with large accumulations of zooplankton and ichthyoplankton, which were registered in August 2021 off the northeastern Black Sea during the period of a tropical-type atmospheric mesocyclone. Intense rains (60–80 millimeters of precipitation) caused flooding and large volumes of terrestrial water entered the sea. Water flows came from rivers into the coastal area and flowed into the CAEs. As a result, there were favorable conditions for the growth of plankton, fish eggs and, larvae. Thus, in the Sochi CAE, against the background of a high concentration of chlorophyll a, and the abundance of small-sized fractions of the fodder zooplankton, there was an almost 30-fold increase in the number of fish larvae (947 ind.·m−2 in the CAE and 33.5 ind.·m−2 in the surrounding waters) and the accumulation of jellyfish Aurelia aurita (Linnaeus, 1758), which is their food competitor, with an abundance of up to 44 ind.·m−2. The data obtained indicates that the Black Sea coastal quasi-stationary anticyclones arise between the cyclonic rim current (Main Black Sea current) and the coast, which can be of great importance in the formation of fish abundance.

Patterns of summer ichthyoplankton distribution, including invasive species, in the Bering and Chukchi Seas

A multidisciplinary survey was carried out in the Pacific Arctic and sub-Arctic regions of the North Pacific Ocean on the Korean icebreaking research vessel Araon. During this survey, ichthyoplankton fishes in the Pacific Arctic and sub-Arctic region ranged from the Bering Sea to the northern Chukchi Shelf in summer. The most dominant species was Gadus chalcogrammus, followed by Pleuronectes quadrituberculatus and Boreogadus saida. Gadus chalcogrammus and P. quadrituberculatus were particularly abundant near the Bering Sea and Bering Strait, whereas B. saida was dominant in the Chukchi Sea. Hierarchical cluster analysis revealed four distinct ichthyoplankton communities in Pacific Arctic and sub-Arctic regions based on geographical regions. However, Eleginus gracilis, which was previously known to be seen between latitudes 66.5°N and 69.5°N, was found above 70°N, suggesting that its distribution extends further north. Furthermore, we noticed that Benthosema glaciale, which is usually found in the Atlantic sector of Arctic Ocean, was observed in the northern Chukchi Sea. In addition to these unusual species distributions, several species that are mainly observed in coastal areas are observed in the Chukchi Sea region. The observed influx of various uncommon fish species into the Chukchi Sea can be attributed to multiple factors, including freshwater inflow from the East Siberian Sea and the intrusion of warm Atlantic and Pacific waters, which are strongly affected by global warming. Consequently, it is imperative to conduct rigorous monitoring of the Pacific Arctic region, with a particular focus on the Chukchi Sea, to better understand the implications of global warming.

Ichthyoplankton in the northern part of the Black Sea under prolongation of summer hydrological season in 2020

The species diversity and spatial distribution of ichthyoplankton in the shelf and deep-sea waters of the northern half of the Black Sea near the Crimean Peninsula and the shores of the Caucasus under the conditions of prolongation of the summer hydrological season 2020 for September–October are presented. The high temperatures of the upper layer of the sea, peculiar of the summer spawning season, caused a continuation of productive spawning of warm-water fish. Eggs and larvae of 19 species from 12 families were identified in the ichthyoplankton. The maximum number of eggs was 302 ind./m2, and larvae — 58 ind./m2. Eggs and larvae of the mass commercial species Engraulis encrasicolus (L., 1758) dominated, whose share in the total population was 92.9 and 84.2% respectively. The highest abundance of ichthyoplankton corresponded to areas with minimal dynamic activity and maximum warming within the limits of coastal-shelf quasi-stationary anticyclonic vortices characteristic of the summer hydrological season.

Regional variability of the Black Sea ichthyoplankton state during the change of the spring hydrological season to the summer

The species diversity and spatial distribution of ichthyoplankton in the coastal and open waters of the northern part of the Black Sea and the southwestern part of the Sea of Azov in June 2020 are presented. The species diversity and abundance of ichthyoplankton changed in accordance with the regional conditions of warming of the sea upper layer during the formation of a vertical thermal structure of the summer type. The most favorable conditions for the survival of ichthyoplankton were observed in the open and coastal waters of the Western Sector of research in the initial phase of the summer hydrological season.

Distribuição do ictioplâncton determinada por diferentes ambientes em uma lagoa costeira de água doce

Abstract Aim This study aimed to evaluate the spatial and temporal distribution of ichthyoplankton in the Peri Lagoon, a coastal freshwater lagoon in Brazil. Methods Ichthyoplankton samples were collected every two months from June 2008 to April 2010 with 500 µm conical-cylindrical planktonic nets at five sampling stations. Results In total, 181 fish eggs and 1,315 larvae, representing estuarine and freshwater species, were captured. The most representative species were Awaous tajasica, Ctenogobius sp1, and Platanichthys platana. Significant differences were found in temporal egg distribution and larval spatiotemporal distribution (Kruskal-Wallis test, p < 0.05). Eggs were predominantly captured during the autumn, winter, and spring Neotropical seasons. Geospatial analysis demonstrated spatial segregation in the distribution of larval assemblages, with higher abundances in areas adjacent to riparian forests, following stream mouths, and deeper areas with rocky substrates. Conclusions Proximity to streams and areas surrounded by dense forests is crucial for the spawning and development of fish species in the Peri Lagoon. The findings of this study provide valuable insights into the conservation of the ichthyofauna in this unique environment.

Assemblage Structure of Ichthyoplankton Communities in the Southern Adriatic Sea (Eastern Mediterranean).

Studies based on fish early life stages can provide information on spawning grounds and nursery areas, helping to determine the implications for stock biomass fluctuations of recruitment variability. This study describes the composition, abundance, spatial distribution and differences in day/night vertical distribution of ichthyoplankton in the southern Adriatic Sea. Samples were collected within the framework of the COCONET project (Towards COast to COast NETworks of marine protected areas) from 9 to 18 May 2013 by the R/V Urania, using the electronic multinet EZ-NET BIONESS (Bedford Institute of Oceanography Net Environmental Sampling System). A total of 20 species, belonging to 20 genera and 13 families, were identified. Of the collected larvae, 74.3% were meso- or bathypelagic species, 24.7% were epipelagic and 0.9% were demersal. The community was dominated by Gonostomatidae, followed by Engraulidae, Myctophidae and Photychthaidae. The most abundant species was Cyclothone braueri (45.6%), followed by Engraulis encrasicolus, Ceratoscopelus maderensis, Cyclothone pygmaea, Vinciguerria attenuata and Myctophum punctatum. An inshore/offshore increasing gradient in biodiversity and abundance was observed. Different weighted mean depths (WMDs) were observed for larvae and juveniles. No diel vertical migrations were observed. The high abundance of meso- or bathypelagic species in the upper 100 m confirms the epipelagic zone as an important environment for the development of the larval stages of these fish.

Mesoscale spatial variability of ichthyoplankton in the Southwest Atlantic during the autumn–winter period

AbstractTo gain a better understanding of the mechanisms underlying spatial heterogeneity in ichthyoplankton communities in the SW Atlantic, we examined for the first time the latitudinal and continental shelf–slope gradients in ichthyoplankton structure and oceanographic features in the Campos Basin during the relaxation phase of coastal upwellings (late autumn to early winter). This region, located on SE Brazil's continental margin, is the most productive offshore oil basin in the country and has ecological relevance owing to the existence of areas that experiences mesoscale (tens to hundreds of kilometers) processes (eddies, filaments, and upwelling) caused by the interaction of continental shelf and slope circulation with deep water masses. The present study collected a total of 3892 fish eggs and 10,030 larvae from 36 sampling stations, averaging 22 eggs per 100 m3 and 56 larvae per 100 m3. A total of 250 taxa (5 for fish eggs and 248 for larvae) were identified, encompassing 80 families and 145 genera. Species distribution exhibited a considerable degree of spatial variability, which was related mostly to hydrological characteristics. In general, greater densities were associated with higher nutrient concentrations areas. Through distance‐based Redundancy Analysis, some discriminating species were found to associate with certain areas of the continental shelf characterized by colder temperatures. The ichthyoplankton distribution patterns suggested a potential influence from mesoscale oceanographic fronts, specifically those that induce upwelling of the cold and nutrient‐rich South Atlantic Central Water. Nonetheless, the methodologies used in this study faced challenges in distinctly identifying these processes.

Metabarcoding of ichthyoplankton communities associated with a highly dynamic shelf region of the southwest Indian Ocean.

Drifting fish eggs and larvae (ichthyoplankton) can be identified to species using DNA metabarcoding, thus allowing for post hoc community analyses at a high taxonomic resolution. We undertook a regional-scale study of ichthyoplankton distribution along the east coast of South Africa, focused on the contrasting environments of the tropical Delagoa and subtropical Natal Ecoregions, and on exposed and sheltered shelf areas. Zooplankton samples were collected with tow nets at discrete stations along cross-shelf transects (20-200 m depth) spaced along a latitudinal gradient that incorporates a known biogeographical boundary. Metabarcoding detected 67 fish species, of which 64 matched prior distribution records of fishes from South Africa, with the remaining three known from the Western Indian Ocean. Coastal, neritic and oceanic species were present, from epi- and mesopelagic to benthopelagic and benthic adult habitats. By family, Myctophidae (10 species), Carangidae, Clupeidae, Labridae (each with 4 species) and Haemulidae (3 species) were most speciose. Ichthyoplankton community composition varied significantly with latitude, distance to coast, and distance to the shelf edge. Small pelagic fishes had the highest frequency of occurrence: Engraulis capensis, Emmelichthys nitidus and Benthosema pterotum increased in frequency towards the north, whereas Etrumeus whiteheadi increased towards the south. Chub mackerel Scomber japonicus accounted for most variability related to distance from the coast, whilst African scad Trachurus delagoa correlated with distance to the shelf edge. Dissimilarity between communities in the Delagoa and Natal Ecoregions was 98-100%, whereas neighbouring transects located within the sheltered KwaZulu-Natal Bight had lower dissimilarity (56-86%). Onshore transport of ichthyoplankton by Agulhas Current intrusions plausibly explained the abundance of mesopelagic species over the shelf. Metabarcoding followed by community analysis revealed a latitudinal gradient in the ichthyoplankton, associations with coastal and shelf-edge processes, and evidence of a spawning area in the sheltered KwaZulu-Natal Bight.

Intra-Decadal (2012-2021) Dynamics of Spatial Ichthyoplankton Distribution in Sevastopol Bay (Black Sea) Affected by Hydrometeorological Factors.

High mortality of fish in the early stages of ontogenesis requires the detection of factors affecting it and is an extremely important problem. For this reason, we tried to consider the influence of some hydrometeorological factors on the intra-decadal dynamics and spatial distribution of ichthyoplankton abundance in Sevastopol Bay. To this end, we analyzed ichthyoplankton samples collected in 2012−2021 in Sevastopol Bay, and the four districts were identified. The ichthyoplankton distribution by areas was associated with the peculiarities of the pollution distribution. The maximum numbers in eggs (34.7 ± 7.5 ind. m−2) and larvae (10.0 ± 2.4 ind. m−2) were recorded in July−August. For the first time, a positive effect of temperature and repeatability of north and northeast winds on the ichthyoplankton number during the summer spawning in all identified areas of Sevastopol Bay using principal component analysis (PCA) was reported. In the southern region, positive influence of temperature and northerly winds on the ichthyoplankton abundance was confirmed by ANOVA (p = 0.02), and Pearson’s correlation analysis revealed significant correlations between these parameters on inter-annual scale (r > 0.5). In the eastern area, the discharge of rivers is an additional factor affecting the abundance of ichthyoplankton, while in the western and central areas, these factors were the wind characteristics caused by the orography peculiarities. The pollution spread in Sevastopol Bay is also largely due to the wind regime. The importance of comprehensive monitoring studies using intra-decadal data on ichthyoplankton is emphasized.

Effects of environmental factors on ichthyoplankton in a permanently open estuary under the influence of a semi-arid climate, north-eastern Brazil

AbstractEstuarine ecosystem conditions actively influence the early life stage of fishes. This study reports how environmental factors influenced the ichthyoplankton in a tropical estuary within an Environmental Protection Area by comparing the structure and composition of fish eggs and larval assemblages. A total of 1672 fish larvae and 486 fish eggs were collected. Higher densities of larvae were recorded for Engraulidae, Characidae, Clupeidae, Gerreidae, Mugilidae and Atherinopsidae, and higher egg densities of the families Mugilidae, Clupeidae and Engraulidae were found. The spatio-temporal variations were determined by the environmental predictors salinity, pH, dissolved oxygen and temperature, with salinity influenced by precipitation as one of the main predictors of the distribution of ichthyoplankton. During the rainy season, greater densities of eggs were recorded in the upper and intermediate zones, mainly Characidae and Engraulidae; in the dry season, in the lower zone, there was a greater density of larvae, particularly Atherinopsidae and Mugilidae. The information provided in the present study contributes to our knowledge of nursery habitat requirements for the initial development of marine migrant and resident species in tropical estuaries.

Vertical distribution patterns of ichthyoplankton in temperate waters of New Zealand

Multifactorial sampling designs were used to determine the vertical distribution of ichthyoplankton at multiple temporal and spatial scales in New Zealand. Hypotheses concerning the vertical distribution of fish larvae were tested in the following: depth strata, surface, near-surface, mid-depth and deep, and near the substratum. The consistency of abundance patterns was examined at three sites separated by 2–20 km over 2 months. We also tested for differences in shallow water columns of two depths (20 and 40 m) and both day and night. Although peak abundance of total larval fish was found at upper and lower strata, regardless of total depth of the water column, consistent taxa specific patterns of vertical distribution were also found. Some taxa were most abundant at the surface (e.g. mullids, hemiramphids, and kyphosids), whereas others were found at multiple depths below the surface and throughout the water column, regardless of site, time or depth of water column (e.g. carangids, engraulids, clupeids, scombrids, sparids and pleuronectids). Some taxa were most abundant in shallow water columns (e.g. mullids, tripterygiids and gobiids). Rank abundance by depth stratum for non-surface dwelling species varied among sites and times. Diel vertical movements were detected, some taxa (e.g. clupeids, scombrids and bothids) that were most abundant at the surface at night whereas for other taxa this pattern was more variable (e.g. carangids). We conclude that diel depth-related patterns in shallow water columns will influence interactions among taxa and the importance of different transport mechanisms for larval transport.

Seasonal and Spatial Distribution Patterns of Ichthyoplankton Along the West Coast of Sri Lanka

Fundamental understanding of fish resources has become a crucial need in Sri Lanka for the sustainable management of fish stocks. Knowledge of ichthyoplankton essential in identifying the spawning dynamics of fish is scarce in this region of the Indian Ocean. A survey was conducted in 2018 covering different monsoon seasons to monitor the abundance, distribution, and diversity of ichthyoplankton along the west coast of Sri Lanka. Samples collected using vertical and horizontal WP2 hauls showed a total of 4095 fish eggs, with identification possible only to 3 families: Clupeidae, Engraulidae, and Cynoglossidae and 465 larval fish belonging to 23 families. The most dominant families recorded were the Siganidae, Blenniidae, Clupeidae, Gobiidae, and Engraulidae, which highlight the importance of pelagic and demersal fish along the west coast. A significant temporal pattern in egg abundance was observed with the highest abundance in March (535 10 m-3) in vertical WP2 net hauls. Furthermore, significant differences in spatial patterns of larval abundance were seen in vertical and horizontal samples. High larval fish abundances were recorded in March and during September - November, with northern regions generally having the highest abundances (~36 larvae 10 m-3). The spawning coincides with the productive southwest monsoon period (May to September). The high diversity and abundance of eggs and larvae recorded in this study indicate that the west coast is likely an important spawning and nursery ground for demersal and pelagic fish.

Ichthyoplankton metabarcoding as a tool for studying fish reproductive dynamics

The study of ichthyoplankton composition, abundance and distribution is paramount to understand the reproductive dynamics of local fish assemblages. The analysis of these parameters allows the identification of spawning sites, nursery areas and migration routes. However, due to the lack of characters in early life stages, the morphological identification of ichthyoplankton is often impractical and many studies identify only fish larvae. Additionally, its accuracy shows great variation between taxonomists and laboratories according to their experience and specialty. DNA barcoding emerged as an alternative to provide assertive identification of fish eggs and larvae, but it becomes too expensive and laborious when the study demands the processing of huge amounts of organisms. DNA metabarcoding can overcome these limitations as a rapid, cost-effective, broad and accurate taxonomy tool, allowing the identification of multiple individuals simultaneously. Here, we present the identification of a sample containing 68 fish eggs and another containing 293 fish larvae from a single site in the São Francisco River Basin, Eastern Brazil, through DNA metabarcoding. We used a low-cost saline DNA extraction followed by PCR amplification with three primer sets targeting the 12S rRNA gene: MiFish (~170bp), Teleo_1 (~60bp), and NeoFish (~190bp). The latter was recently developed by our research group specifically for the identification of Neotropical fishes. All the amplified samples were sequenced in a single multiplexed Illumina MiniSeq run. We performed the filtering steps and assigned Amplicon Sequence Variants (ASVs) using a DADA2/Phyloseq based pipeline and a custom 12S reference sequence database including 101 species and 70 genera from the Jequitinhonha and São Francisco basins. The species Cyphocharax gilbert, Leporinus taeniatus, Megaleporinus elongatus, Prochilodus argenteus, P. costatus and Psalidodon fasciatus were detected by all three primer sets in the larva pool, while Pterygoplichthys etentaculatus was detected solely by NeoFish (Fig. 1). Within the egg pool, all three markers detected the species Characidium zebra, Curimatella lepidura, M. elongatus, Pimelodus fur and P. costatus, but Brycon orthotaenia was detected only by NeoFish, P. maculatus only by Teleo, and P. pohli by MiFish and Teleo (Fig. 1). The consistency in species detection among all three markers underpins the credibility of this method to accurately describe the sample composition. Considering that most of species were exclusive to the larvae or egg pool, our experiment highlights the importance of including the identification of fish eggs in reproduction studies, as it can provide additional information about which species are spawning in an area. Furthermore, the application of DNA metabarcoding to the study of ichthyoplankton can help decision makers create more informed guidelines for conservation of economically and ecologically important fish species.

Distribution of Ichthyoplankton in Relation to Specifics of Hydrological Regime off the Crimean coast (the Black Sea) in the Spring–Summer Season 2017

The paper presents characteristics of the species composition, spatial distribution, and trophic interactions of ichthyoplankton and zooplankton in the spring–summer period 2017 dependent on intensity of the warming-up of the upper sea layer against the background of transition in a system of the surface currents from the winter-to summer-type of the circulation. In April–May, successful spawning of temperate-water fish species was prolonged due to low values of the sea surface temperature (8–9°С) on the shelf of Crimean Peninsula between Kerch Strait and the cape Sarych. The maximum abundance of Sprattus sprattus eggs was 162.8 egg/m2 and larvae –116 ind/m2. Warm-water species occurred only in the western sector from Herakleian Peninsula to the Cape Tarkhankut, where the water temperature was at its maximum and peaked at 14–15°С. In June–July the delayed summer hydrological season hampered the warming-up of the upper quasi-homogenous layer, which thickness varied from 1–5 to 10–15 m. Notwithstanding the large number of species in the ichthyoplankton, maximum abundance did not exceed 50 egg/m2 and 14 ind/m2 for larvae. The proportion of larvae of temperate-water fish species averaged 32% and reached 40% in deep water areas. Juvenile stages of copepods of the cold-water complex were dominant in the larval fish diet both in the spring and summer seasons.

Ekologicheskoye sostoyaniye akvatorii Vostochnogo Sivasha v ranneletniy sezon 2020 goda

The paper studies the ecosystem of the Eastern Sivash in the context of natural and anthropogenic influence. The data collected during the expedition of the Azov-Black Sea Branch of the FSBSI “VNIRO” conducted in early summer 2020 were used as original empirical evidence. Specific features of hydrological and hydrochemical conditions, as well as species composition, distribution, and abundance of ichthyoplankton were indicated. It was shown that the values of pH, nitrates, nitrites, and phosphates did not exceed MPCs established for fishery water bodies within the entire water area under study; the range of dissolved oxygen content was wide: 3.63–9.13 mg/dm3 . By comparison of the environmental status of the biocoenoses during early summer 2020 with the data collected during a similar survey in 2019, it was found that the water temperature at site 4 is lower by 1.9–2.7 °C. Further salinization of the Sivash was recorded: the lowest salinity in 2019 ranged within 32–38 ‰ and the highest one ranged within 83–86 ‰; in 2020, these values were 36–43 ‰ and 91–97 ‰, respectively. In terms of spatial distribution, the range of the increase in salinity was 4.36–16.69 ‰, with the highest value being recorded at site 2 (11.51–16.69 ‰) and the eastern part of site 3 (13.22 ‰). To a lesser extent (by 4.36–6.26 ‰), an increase in salinity was recorded at site 4 and the western part (5.27 ‰) of site 3. The results of plankton net surveys showed that ichthyoplankton was represented almost exclusively by larvae of big-scale send smelt, which had the densest distribution at site 1 at a salinity of 89 ‰, and on the border between sites 2 and 3 at a salinity of 74 ‰. The upper limit of salinity at which this fish reproduction is possible lies within the range 75–90 ‰. The absence of so-iuy mullet eggs and juveniles at a salinity higher than 32–36 ‰ in May – June of 2019–2020 during the peak of so-iuy mullet spawning does not provide a reason to include the Sivash Bay among the Azov Sea areas important for reproduction of this fish species

Distribución del Ictioplancton y su interrelación con parámetros bióticos y abióticos en aguas costeras ecuatorianas

The biotic and abiotic conditions of the marine ecosystem affect the spawning grounds of fish and therefore the development and behavior of fish larvae in the Ecuadorian coast. During the cruise demersal fishing T 05/11 / 01D of November 2005, 44 zooplankton samples were collected with a simple conical network of 300 micron mesh. Ichthyoplankton distribution indicated a high density of larvae, 8800larvae / 10m2, in front of Muisne and 24 000 and 15 000 eggs / 10m2, in front of Cabuyal and Gulf of Guayaquil, respectively. The area between Cabo San Lorenzo until Cabuyal was the greatest diversity of fish larvae (4.26 bits) related with concentrations of diatoms and dinoflagellates, in an area characterized by mixingfresh water from the Chone River and oceanic warm waters of the Panama bay. The Gulf of Guayaquil was second in ichthyoplanktonic diversity associated with increased zooplankton, especially copepods and cladocerans (3.7 bits).Temperature, salinity, nutrients, and diatoms were the parameters of highest incidence in the distribution of larvae on the coast of Ecuador (r = 0.6 to 0.88). Interrelationships among phosphates, diatoms, zooplankton, fish larvae and adults fishes of Chloroscombrus orqueta, were observed.

Long-term changes of ichthyoplankton communities in an Iberian estuary are driven by varying hydrodynamic conditions

Abstract Ichthyoplankton assemblages are key components of estuaries worldwide, playing a vital role as nurseries for fish larvae. Nonetheless, estuaries can be highly affected by ongoing climate change. Impacts of climate variability on ichthyoplankton assemblages will have consequences for marine pelagic food webs and fish populations biology, namely recruitment. This study aims to investigate the influence of environmental variability on an interannual abundance of ichthyoplankton assemblages of the Mondego estuary (Portugal). For this, an ichthyoplankton sampling programme of 13 years (2003–2015) along six distinct sampling stations was analysed to evaluate spatial, seasonal and interannual changes of ichthyoplankton distribution over periods of wet, regular and dry conditions. The ichthyoplanktonic community was dominated by Pomatoschistus spp. across all seasons and conditions, with higher larval abundances during summer and spring. Main changes were related to species seasonality and phenology as well as an increase in the number of marine species during extreme events. The larval fish community showed a strong relationship with the regional and local environment over the study, presenting a distinct yet highly variable structure during the 2009–2013 period. Reported changes will likely trigger major changes in species dominance and abundance, with clear ecological and socio-economic implications.