Effects of Interannual Environmental Changes on Juvenile Fish Settlement in Coastal Nurseries: The Case of the Adriatic Sea

Sanja Matić-Skoko,Dubravka Bojanić Varezić,Pero Tutman,Mišo Pavičić,Hana Uvanović,Dario Vrdoljak,Marcelo Kovačić

doi:10.3389/fmars.2022.849092

Sanja Matić-Skoko, Dubravka Bojanić Varezić + Show 5 more

Open Access

https://doi.org/10.3389/fmars.2022.849092

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Abstract

This study tested generality in the settlement and recruitment patterns of juvenile fish in the coastal Mediterranean as driven by interannual environmental differences. A multivariate analysis of juvenile fish community data, sampled over three consecutive years, was conducted to elucidate the interannual changes of new settlers’ occurrence and abundance in different nurseries along the eastern Adriatic coast. Sites were assigned to four groups of nurseries based on water type (marine or transitional) and geographical position (north or south). Statistically significant interannual differences were found in temperature but not in salinity. In general, species occurrence significantly fluctuated between years and seasons. The highest total abundance of juveniles was observed in the significantly warmer year 2018 within all study groups. Defined groups expressed significant annual differences in species richness and abundance related to variations in water temperature and salinity as environmental factors for the same consecutive years. Nurseries within transitional waters in the north are more prone to interannual water temperature changes. The associated community composition differed most from those recorded in southern marine waters, where groups were mostly defined by salinity influence and were least sensitive to interannual temperature fluctuations. The cold and rainy spring in 2019 caused late settlement and longer retention of specific economically and ecologically important fish species in the nurseries. The results suggested that settlers’ delay or retention due to negative temperature deviation in the spawning period were linked to the nurseries located in the northern transitional waters that are under a stronger coastal influence. These delays can have ecological consequences on population dynamics and on inter- and intraspecific relationships within specific nursery communities.

Highlights

Coastal areas are commonly acknowledged as highly productive and valuable ecosystems that provide many favourable habitats for fish, while supporting fundamental ecological links with other environments (Duarte, 2000; Beck et al, 2001; Hinz et al, 2019)
72.88 and 71.67% of samples were correctly allocated to north or south, respectively. These results suggested that transitional waters are more sensitive to interannual differences, especially in the north (Figure 6)
The present study focussed on the patterns of use of coastal nurseries by juvenile fish species along the eastern Adriatic coast

Summary

Introduction

Coastal areas are commonly acknowledged as highly productive and valuable ecosystems that provide many favourable habitats for fish, while supporting fundamental ecological links with other environments (Duarte, 2000; Beck et al, 2001; Hinz et al, 2019). Their role in early life stages, and as foraging and spawning grounds for non-coastal fish species Marine ecosystems have been degraded in many areas, in the Mediterranean, and many critical coastal habitats are no longer available or adequate to provide nursery, feeding, or reproductive functions, with negative consequences on production and renewal of populations (Guidetti et al, 2002; Barbier et al, 2011; Matic-Skoko et al, 2020)

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