Comparative Toxicity of “Tin Free” Self-Polishing Copolymer Antifouling Paints and Their Inhibitory Effects on Larval Development of a Non-Target Organism

Toxic substances released as a result of leaching from painted surfaces to the aquatic environment affect both fouling organisms and “non-target” biota. Artemia fransiscana nauplii have been considered a useful test system for the examination of toxicity for antifouling paints. In this study, we examined the effect of four “tin free” self-polishing copolymer (SPC) antifouling paints on the larval development of Artemia nauplii. Based on the L(S/V)50 values the order of toxicity of the antifouling paints was: ANTI F > SHARKSKIN > OCEAN T/F > MICRON. Furthermore, the body size of Artemia nauplii was significantly affected at lethal and above lethal L(S/V)5024h values. The body size of 48 h-aged nauplii exposed for the last 24 hours to each of the four SPC antifouling paints was significantly lower than that of the 48 h-aged controls (0.88 ± 0.030 mm). In addition, the body size of 72 h-aged nauplii maintained for the last 24 hours to pure synthetic seawater after exposure for 24 hours to each of the four SPC antifouling paints was significantly lower than that of the 72 h-aged controls (0.96 ±0.027 mm). Overall, the SPCs examined here were substantially toxic to Artemia nauplii, but with different toxicities and modes of action, as a result of the synergistic action of distinct components of the antifouling paints.

Effective algorithmic operational framework for fish texture evaluation in industry:Achieving maturity

Reliable,nondestructive fish freshness evaluation applicable during fish commercialization has been continuously pursued by scientists and industry.Taking into account that fish texture is primarily affected even at early stages of post-mortem storage,a relevant nondestructive testing framework for rapid textural assessment of fish freshness was developed in the past.Herein,an algorithm operating within the aforementioned framework and optimized for use in industrial environments is proposed.Sea bass(Dicentrarchus labrax)both freshly killed and stored on ice for 6 days have been used for comparative testing.The fish is part of a system,which is vibrationtested via a new testing protocol designed for easy implementation and robustness to noise.At the same time,a new closed-form analytical expression for the system response to the specific testing is computed and used along with experimental data,for obtaining specific mechanical(thus muscle-structural)characteristics of fish flesh.This computation is designed to only require readily available routines found in most relevant software.The algorithmic operational framework has been used in two different test setups(a custom-built test rig and a prototype device),with results following remarkably similar trends,clearly discriminating different textural(thus freshness)characteristics,and consequently validating the proposed approach.

Evolution of sex ratio and egg production of gilthead seabream(Sparus aurata)over the course of five reproductive seasons

Spawning performance-relative fecundity and fertilization success-was studied in two hatchery-reared broodstocks of gilthead seabream(Sparus aurata)held under relatively constant well-water temperature(18-20◦C)and simulated natural photoperiod,for five consecutive spawning seasons,between 3 and 7 years of age.The spawning season lasted between 4 and 6 months each year,and the total number of eggs produced annually ranged between 1480000 and 3100000 eggs/kg female body weight,being the highest during the first and second spawning season.No difference was observed in monthly relative fecundity between years-although high variation existed within years,whereas fertilization success was the highest during the second and third reproductive season,and dropped significantly during the last year of the study.The male percentage of the broodstocks was 35%during the first spawning season of the females,and thereafter it decreased further and remained stable at around 15%-20%for the second and third spawning season.Substitution of older females with smaller males to readjust male percentage to 50%in the fourth spawning season,was followed by sex change of larger males to females and a drop of the male percentage to 18%in the following spawning season.The present study demonstrated the long spawning season of gilthead seabream-especially under constant water temperature,the high fecundity and fertilization success,and the stabilization of male percentage to~20%after the first spawning season or when a broodstock is modified to increase male percentage.These results are useful to the aquaculture industry,demonstrating that there is no need to add males to gilthead seabream broodstocks over the years,as the sex ratio is stabilized and egg production and fertilization success remain high with a relatively low male:female sex ratio.