Contamination in newly hatched larvae of the mangrove crab Ucides cordatus and a new perspective about trace elements transport

Eduardo Almeida,Vinícius Kütter,Emmanoel Silva-Filho

doi:10.21715/gb2358-2812.2021351039

Abstract

Mangroves are relevant ecosystems due to their ecological role, economic use, and social importance. One of the most abundant and important species in Brazilian mangroves is the exploited crab Ucides cordatus. This study focuses on this species and the aim was to evaluate the concentration of trace elements in the hepatopancreas of ovigerous females, eggs (pre-hatching and hatching stages), and for the first time, in newly hatched larvae. Ovigerous females were captured in two Southeastern Brazil mangroves (Guanabara Bay and Paraíba do Sul River’s secondary estuary) and spawning was held in spawning tanks, in the laboratory. Some females were not taken to the tanks, but they were frozen right after collection. There was no significant difference in trace element concentration between these females and those kept in the spawning tanks. Both essential and non-essential trace elements were detected in newly hatched larvae. Comparing with the adult female, the elements Zn, Cu, and Mn showed the highest concentrations in larvae and eggs. Vanadium, Cr, and Mn concentrations were significantly higher in hatching eggs than observed in newly hatched larvae, indicating the retention of elements in the eggshell. Considering the V (0.17 - 1.17 μg.g−1 dry weight), Cu (14.1 - 41.1 μg.g−1 dry weight), and Zn (235.4 - 263.9 μg.g−1 dry weight) concentrations in newly hatched larvae, with the same order of magnitude observed in suspended particulate matter (SPM) and sediments in suspension, the planktonic larval dispersion could result in the transport of elements beyond the mangrove, and their introduction in coastal waters.

Highlights

Human activities have resulted in a large2012), Callinectes sp. (LAVRADAS et al, 2014), introduction of trace elements into the and Ucides cordatus (ALMEIDA et al, 2016).environment, and high concentrations of theseRegarding crab larvae, there is a predominance of elements in coastal sediments have been a great ecotoxicological studies (LÓPEZ-GRECO et al, concern in recent decades (RAINBOW; 2002; FERRER et al, 2006; AMIN; FURNESS, 2018)
The Ucides cordatus females sampling was made in the same locations and with the same methods seen in Almeida et al (2016)
The two study sites were the Caceribu River mangrove (Guanabara Bay - GB) and the Gargaú mangrove (Paraíba do Sul River, secondary estuary - PSR), which are in SE Brazil (Fig. 1)

Summary

Introduction

Human activities have resulted in a large2012), Callinectes sp. (LAVRADAS et al, 2014), introduction of trace elements into the and Ucides cordatus (ALMEIDA et al, 2016).environment, and high concentrations of theseRegarding crab larvae, there is a predominance of elements in coastal sediments have been a great ecotoxicological studies (LÓPEZ-GRECO et al, concern in recent decades (RAINBOW; 2002; FERRER et al, 2006; AMIN; FURNESS, 2018). In elements is more notable in low hydrodynamic marine species, previous studies were limited to environments with high deposition rates, such as the analysis of maternal tissues and egg lagoons, bays, and deltas. Among these contamination, whereas newly hatched larvae environments there are the mangroves, coastal were rarely considered. Whereas newly hatched larvae environments there are the mangroves, coastal were rarely considered Up to this date, no study ecosystems with extensive deposition of fine has focused on the contamination of newly sediments – which are considered geochemical hatched larvae. When females and early stages are barriers due to the physical retention of particles disregarded in contamination studies, valuable

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Results