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Understanding sources of variability in larval supply and transport is integral to the dynamics, structure and effective management of marine populations and communities. Yet, a barrier to this understanding is the high variability in the supply and transport of marine larvae, especially in upwelling regions where wind forcing causes dynamic circulation. Since larvae of many species complete development close to shore, resolving the relationship between oceanographic processes and nearshore larval assemblages is essential to better understand larval transport in highly productive upwelling regions. The goal of our study was to examine the effects of variation in upwelling and relaxation dynamics on the nearshore larval assemblage in northern Monterey Bay. To determine how seasonal and daily upwelling and relaxation dynamics influence the nearshore larval assemblage, we surveyed distributions of marine larvae and physical, environmental factors along a cross-shelf transect in northern Monterey Bay, USA, during August and October of 2013. Conditions in August and October differed in temperature, salinity, stratification, and chlorophyll-a fluorescence. Richness and diversity of the larval assemblage did not change appreciably, but the abundance and composition of species shifted after the influx of offshore waters. Specifically, nearshore taxa were more abundant during August, which was characterized by strong upwelling conditions, and especially more abundant with increased wind forcing leading to a retentive upwelling shadow in the northern bay. Conversely, offshore taxa were more abundant during October, which was characterized by weakened upwelling and the persistent influx of offshore water. Our study suggests that relationships between larval taxa, life history characteristics, and water types provide insights into water mass history, circulation and larval recruitment in highly dynamic upwelling regions.

Understanding sources of variability in larval supply and transport is integral to the dynamics, structure and effective management of marine populations and communities. Yet, a barrier to this understanding is the high variability in the supply and transport of marine larvae, especially in upwelling regions where wind forcing causes dynamic circulation. Since larvae of many species complete development close to shore, resolving the relationship between oceanographic processes and nearshore larval assemblages is essential to better understand larval transport in highly productive upwelling regions. The goal of our study was to examine the effects of variation in upwelling and relaxation dynamics on the nearshore larval assemblage in northern Monterey Bay. To determine how seasonal and daily upwelling and relaxation dynamics influence the nearshore larval assemblage, we surveyed distributions of marine larvae and physical, environmental factors along a cross-shelf transect in northern Monterey Bay, USA, during August and October of 2013. Conditions in August and October differed in temperature, salinity, stratification, and chlorophyll-a fluorescence. Richness and diversity of the larval assemblage did not change appreciably, but the abundance and composition of species shifted after the influx of offshore waters. Specifically, nearshore taxa were more abundant during August, which was characterized by strong upwelling conditions, and especially more abundant with increased wind forcing leading to a retentive upwelling shadow in the northern bay. Conversely, offshore taxa were more abundant during October, which was characterized by weakened upwelling and the persistent influx of offshore water. Our study suggests that relationships between larval taxa, life history characteristics, and water types provide insights into water mass history, circulation and larval recruitment in highly dynamic upwelling regions.

Odonata larvae have been intensively used as bioindicators for freshwater pollution as their community structure closely follow changes in the environment and habitat settings. In this study, 28 taxa of Odonata larvae were collected from three stations (upper, middle and lower) of a polluted river in Malaysia. The upper river basin receives effluents from an oil palm plantation. However, the middle station is presumably contaminated with anthropogenic wastes. The lower station is found to receive polluted discharges from aquaculture outlet. Several environmental parameters of water and sediment were continuously measured during the study. The water parameters showed no significant differences amongst the three stations. The species richness of Odonata was 22, 24 and 20 in the upper, middle and lower stations, respectively. The abundance of Odonata was significantly different among the studied sites. The tolerant damselfly, Pseudagrion sp. (41.22%), and facultative dragonflies, Onychothemis sp. (17.12%), were the most dominant taxa along the river stations. Onychothemis sp. and Paragomphus capricornis were equally important at the upper station [Important Species Index (ISI) 25.3 and 24.2%, respectively]. Pseudagrion sp. only scored an ISI value of 9.7%. Pseudagrion sp., P. capricornis and Onychothemis sp. were dominant in the middle station (ISI: 41.2%, 25.9% and 10.9% respectively), and Pseudagrion sp., Onychothemis sp. and Prodasineura sp. dominated the areas with dense growth of submerged aquatic weeds Hydrilla sp. in the lower station (ISI: 47.9, 24.5 and 13.8%, respectively). On the basis of the variations in larval abundance and ISI values, microhabitats differences partly in response to different types of pollutions entering the water structured the Odonata communities in this river basin.

Although many anuran species in Japanese paddy ecosystems are decreasing because of recent modernization of rice paddies, Fejervarya kawamurai is one of the exceptions, being extremely abundant even in modernized paddies. To understand the reason for this phenomenon, we collected specimens of anuran larvae in 92 paddy fields in west Mikawa area, Aichi Pref., Japan, and examined the biotic and abiotic factors affecting the density of F. kawamurai using model selection procedure with GLMM. The best model indicated that larval F. kawamurai tended to be abundant in paddies with low larval densities of Hyla japonica and Pelophylax nigromaculatus. Considering that F. kawamurai tends to start breeding later in the season than H. japonica and P. nigromaculatus, we hypothesize there are some negative effects of these preceding larvae on larval F. kawamurai. Such interspecific interactions are thought to have acted as an ecological constraint for F. kawamurai in the traditional Japanese paddy ecosystem, where many anuran species sympatrically breed. Recent decrease of some early breeders like P. nigromaculatus, however, would provide relief from such restrictions to F. kawamurai, and might promote the population increase and distribution expansion of this species. [ABSTRACT FROM AUTHOR]

Spatio-temporal distribution and composition of ichthyoplankton assemblages were studied in the Golden Horn estuary (Istanbul) over a 10-month period. Environmental parameters were considered to determine the environmental status in different parts (upper, middle and lower) of the estuary. The ichthyoplankton composition of the Golden Horn estuary consisted of 23 species and was dominated by Mullus sp., Diplodus spp. and Liza sp. The largest densities of fish eggs and larvae were found in September 2009 with 786.4 ind. 100 m–3 and 355.9 ind. 100 m−3, respectively. As supported by the multivariate analysis, most species showed a seasonal pattern, with the presence of higher densities during summer and winter. Moreover, the spatial pattern showed that ichthyoplankton distribution and diversity was relatively high in the lower part of the Golden Horn and gradually decreased through the upper parts. Canonical correspondence analysis revealed that spatial changes in depth and water clarity were the main factors forcing larval assemblage distribution and leading to a decrease in density and diversity of fish larvae through the upper part of the estuary. For the seasonal changes, sea surface salinity and chlorophyll a were the main factors in shaping the structure of the larval assemblage and increasing sea surface temperature lead to an increase in the density and diversity of fish larvae. [ABSTRACT FROM AUTHOR]

The early life stages of the Antarctic silverfish ( Pleuragramma antarctica), an important prey species for higher predators in the Southern Ocean ecosystem, dominate the larval fish assemblages of the Bransfield Strait, one of the most important areas for larval retention off the Antarctic Peninsula. Nevertheless, the spatial location of areas where they were spawned and the timing of larval hatching remain unknown. By linking Lagrangian particle tracking simulations with age data obtained using otolith microincrements from fish caught north of Joinville Island in a pelagic survey, we estimated the distribution of hatch dates and subsequent growth rates of silverfish reaching the Bransfield Strait, and predicted the areas where they were spawned. Larval hatching peaked during the last week of December, and the inner shelf and shelf break, east of the Larsen Ice shelf, were the dominant areas predicted to contribute to larval assemblages in the Bransfield Strait. Over simulated periods of 600-630 days, 35-40% of particles remained within the Bransfield Strait, suggesting an important source of supply to higher predators feeding off the northern Antarctic Peninsula. The daily growth rate at the mean size of 22.3 mm was 0.18 mm, corresponding to a daily change in size of approximately 0.82% standard length ( SL), and large variability in growth rate suggested a wide range of environmental conditions experienced during the period of advection from the spawning areas. These results provide spatial predictions that can be tested empirically in future studies, using the simulated trajectories to inform sampling design and spatial coverage. [ABSTRACT FROM AUTHOR]

Estuaries are important nursery areas for fishes worldwide but large-scale studies of spatial patterns of use are lacking. This study presents data on larval fish diversity, abundance and distribution within and among a range of temperate estuary types, spanning 25 systems sampled from 1998 to 2008 in South Africa. A standardized boat-based plankton towing technique was used. Estuary type and physico-chemical conditions played a defining role in the trends observed. Estuary resident Clupeidae and Gobiidae dominated the mid-channel larval catch, particularly the preflexion stages in permanently and intermittently open estuaries and in estuarine lakes. Permanently open estuaries were also characterized by high numbers of larvae and early juveniles of marine migrant fishes. Density was higher in warmer months (spring and summer), which coincides with peak spawning in coastal habitats coupled with zooplankton maxima in the warm-temperate region. A strong seasonal component was also evident in larval fish catches in cool-temperate systems, but this peak coincided with late winter rainfall. River inflow provides a strong influence on food availability and larval survival. Species richness and diversity was higher in estuaries with either extensive habitat variability and/or a strong, natural good supply of river flow. This was particularly evident in the higher numbers of marine migrant larvae in these systems. Freshwater deprived estuaries also displayed high species diversity due to the higher incidence of marine straggler species. Characterization of salinity into zones provided a valuable means to understand distribution and abundance dynamics. Mesohaline zones had the highest density of larval fishes, providing ideal food patches. A select suite of species dominate the larval fish assemblages in the various estuary types studied. These patterns persist but species abundance and rank may vary interannually based on productivity and larval fish survival. [ABSTRACT FROM AUTHOR]

• Oceanographic conditions and the larval assemblage varied seasonally in Monterey Bay, CA, USA. • Upwelling and relaxation dynamics affected the phytoplankton and larval assemblages. • Nearshore larval taxa and diatoms were abundant during strong upwelling conditions. • Offshore larval taxa and dinoflagellates were more abundant with the influx of offshore water. • Source water variation and meroplankton composition may provide insight into larval supply dynamics. Understanding sources of variability in larval supply and transport is integral to the dynamics, structure and effective management of marine populations and communities. Yet, a barrier to this understanding is the high variability in the supply and transport of marine larvae, especially in upwelling regions where wind forcing causes dynamic circulation. Since larvae of many species complete development close to shore, resolving the relationship between oceanographic processes and nearshore larval assemblages is essential to better understand larval transport in highly productive upwelling regions. The goal of our study was to examine the effects of variation in upwelling and relaxation dynamics on the nearshore larval assemblage in northern Monterey Bay. To determine how seasonal and daily upwelling and relaxation dynamics influence the nearshore larval assemblage, we surveyed distributions of marine larvae and physical, environmental factors along a cross-shelf transect in northern Monterey Bay, USA, during August and October of 2013. Conditions in August and October differed in temperature, salinity, stratification, and chlorophyll- a fluorescence. Richness and diversity of the larval assemblage did not change appreciably, but the abundance and composition of species shifted after the influx of offshore waters. Specifically, nearshore taxa were more abundant during August, which was characterized by strong upwelling conditions, and especially more abundant with increased wind forcing leading to a retentive upwelling shadow in the northern bay. Conversely, offshore taxa were more abundant during October, which was characterized by weakened upwelling and the persistent influx of offshore water. Our study suggests that relationships between larval taxa, life history characteristics, and water types provide insights into water mass history, circulation and larval recruitment in highly dynamic upwelling regions. [ABSTRACT FROM AUTHOR]