Chitin was extracted from Polybius henslowii, a swimming crab, captured in large quantities throughout the Portuguese coast by purse seine vessels as bycatch. After standard chitin extraction procedures, water-soluble chitosan products were obtained via two different methods: (1) N-acetylation with the addition of acetic anhydride and (2) a reaction with hydrogen peroxide. The chemical structure and molecular weight of chitosan derivatives, water-soluble chitosan (WSC) and chitooligosaccharides (COS), were confirmed by Fourier Transform Infrared Spectroscopy (FT-IR) and gel permeation chromatography (GPC). Antioxidant and metal chelation activities were evaluated, and the growth inhibition capacity was tested on four phytopatogens. The chitooligosaccharides from pereopods (pCOS) and shell body parts (sCOS) inhibited all fungal species tested, particularly Cryphonectria parasitica with 84.7% and 85.5%, respectively. Both radical scavenging and antifungal activities proved to be dose-dependent. Chitooligosaccharides with a low molecular weight (2.7, 7.4, and 10.4 Kg·mol⁻¹) showed the highest activity among all properties tested. These results suggested that chitosan derivatives from P. henslowii raw material could potentially be used against phytopathogens or as ingredient in cosmetics and other products related to oxidative stress.

This study compares the effect of temperature on the post-embryonic development time and weight-specific growth rate in 2 populations of Acartia clausi from different biogeographic areas (northern and southern Europe). Development was followed from nauplius I to adult at 3 temperatures (10, 15 and 18°C) at saturating food conditions. The relationship between development time and temperature was established by fitting Belehradek’s function. The northern population had a shorter generation time at all temperatures. At 10°C, the development time was estimated to be 33.9 and 36.4 d decreasing to 16.3 and 17.4 d at 18°C for the northern and southern populations, respectively. Prosome length decreased with temperature, and the southern population had longer individuals at all temperatures. ANCOVA revealed a significant (p < 0.001) positive effect of temperature on the growth rates, and nauplii grew faster than copepodites (except at 18°C in the southern population and 20°C in the northern population). Significant differences between populations were noted during larval growth, with nauplii from the north growing faster at high temperatures (18°C). The results indicate that the 2 A. clausi allopatric populations subjected to different temperature regimes have different temperature responses, in particular at high temperatures