Interannual summer biodiversity changes in ichthyoplankton assemblages of the Strait of Sicily (Central Mediterranean) over the period 2001–2016

Abstract

Interannual fluctuations in the structure and the composition of ichthyoplankton assemblages in the pelagic waters of the Strait of Sicily (SoS, Central Mediterranean) were investigated, trying to relate them to the observed variability in oceanographic conditions. Plankton data used in this study were from 16 summer surveys carried out in the SoS every year from 2001 to 2016, using oblique bongo plankton net (0–100 m) tows. Out of more than 12,000 fish larvae collected in the sampling stations included in the analysis, 9,519 of them were identified and regularly classified in 15 orders and 49 families. Ichthyoplankton assemblages, defined at the family level due to the uniform availability of this information along the time series, showed a decreasing trend over time in total larval abundance, along with taxonomic (family) richness and Shannon index (α diversity), more pronounced in the shelf area and in the slope area, respectively. Conversely, the relatively high levels of yearly compositional changes observed in the larval assemblage from both shelf and slope areas, as estimated by the Jaccard dissimilarity index (β diversity), did not show any significant linear trend. In addition, a biodiversity hotspot (both in terms of family richness and Shannon index) was evidenced in the frontal structure characterizing the southeastern part of the study area. Generalized additive models were used to evaluate the effect of oceanographic conditions on the temporal and spatial patterns of ichthyoplankton biodiversity. Results evidenced the role of salinity, surface temperature, and surface currents in modulating biodiversity indices, especially in the shelf area. Finally, the relevance of local frontal oceanographic structures in sustaining high biodiversity levels is postulated.

A hierarchical Bayesian model to monitor pelagic larvae in response to environmental changes

“…This phenomenon allows us to measure the reproductive capacity of fish species such as anchovies and sardines, offering an index of their relative population size (Allen et al 2006). Several factors affect the composition and abundance of larval fish communities (Boehlert and Mundy 1993;Patti et al 2022). An important factor is the spawning strategy adopted by the adult populations, which are linked to topographical characteristics and hydrographical, chemical and biological conditions (Basilone et al 2006;Patti et al 2020).…”

Evaluating Metabarcoding Markers for Identifying Zooplankton and Ichthyoplankton Communities to Species in the Salish Sea: Morphological Comparisons and Rare, Threatened or Invasive Species

“…These species frequently interact together, accentuating or dampening the effects of environmental stressors on one another. Notably, coastal zooplankton and ichthyoplankton communities are regarded as some of the most vulnerable to ocean acidification (OA), hypoxia (H), and warming [4][5][6] and are subject to other environmental, chemical, physical, and biological fluctuating conditions (e.g., [7,8]). Moreover, their larval stages often lack species-level diagnostic morphological characters, precluding their identifications using microscopy and DNA 2024, 4 2 other morphology techniques [9][10][11][12][13].…”

“…DNA 2024, 4, FOR PEER REVIEW 2 physical, and biological fluctuating conditions (e.g., [7,8]). Moreover, their larval stages often lack species-level diagnostic morphological characters, precluding their identifications using microscopy and other morphology techniques [9][10][11][12][13].…”

“…The various species comprising zooplankton and ichthyoplankton communities are not ecologically interchangeable, often respond differentially to environmental stressors, and may occur at various times and places [7,8,[10][11][12][13]. In other words, these are dynamic communities upon which other organisms depend for food [25][26][27], and they are critical to ecosystem services and seafood resources [12,13,16].…”

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

“…Studies carried out on fish early life stages can provide information on spawning grounds and nursery areas, which is useful for ascertaining recruitment variability and the resultant stock biomass variability [9,10]. Likewise, studies on the composition, density and spatial distribution of fish larvae in relation to environmental parameters are very important, since the survival and growth of many fish species are linked to the impact of the marine environment on these early developmental stages [11].…”