Sex differentiation in the histology of the digestive gland ofNephrops norvegicusfrom Pagasitikos Gulf during spring

Abstract

The aim of this research is to study the seasonal histological changes in the digestive gland of males and females Nephrops norvegicus at the Pagasitikos Gulf. The food availability in Pagasitikos Gulf varies and depends on the seasonality, physicochemical conditions and diversification of organic material. After obtaining histological sections, the size of tubules, their lumens and the R-, F-and B-cells were calculated in March and May. A special image analysis algorithm was used that can automatically calculate both the above area ratios using digestive gland histological sections. Both male and female, which were sampled in May, had a larger density of lipid droplets than N. norvegicus sampled in March. However, females sampled in May had more lipid droplets per tubule and a smaller F-cell-to-tubule ratio than males, which indicated that the intensive feeding period had started for reproduction in the females. The digestive gland can be used as a nutritional indicator to assess the nutritional status of Nephrops stocks and to assist with the management of the Nephrops wild stocks by proposing a seasonal fishery management plan to improve the sustainability of the stocks.

Population Dynamics, Fishery, and Exploitation Status of Norway Lobster (Nephrops norvegicus) in Eastern Mediterranean

“…By assuming that the first representative mode of the MPA groups corresponds to an absolute age of 3.5 years, the estimated SOM of this study is estimated between 5 and 6 years, which is similar to other studies [2,11,13,30,32,56,57]. Since mesh sizes in fishing gear are set within the framework of an effective management policy by official bodies (e.g., EU, Central Government, Local Authorities), in order to reduce the capture of immature individuals [52], it is important to note that the regional legal minimum mesh size for creels (28 mm) and gillnets (26 mm) for Nephrops fisheries in Greece [44] is lower than the estimated SOM of this study. This difference should be put under consideration by the regional policy makers and stakeholders in Nephrops fishery, since it could pose as a potential threat in the long-term viability of the stocks.…”

“…Due to its importance and high economic value as a commercial species in the Atlantic and North Sea [2,3,9], Nephrops has been the subject of several biological and fishery studies , leading to the collection of long time series data for that region. In regard to the Mediterranean Sea, most of the studies have focused on the Western region and the Adriatic sea [7,8,13,15,[30][31][32][33][34][35][36][37][38], with the majority of them within the framework of the EU research project "MEDITS" [39], contrary to even fewer studies in the Eastern Mediterranean and the Aegean Sea [40][41][42][43][44]. The aim of the present study was to fill that knowledge gap in the Eastern Mediterranean, since no such studies were found for the region.…”

“…Trawling is prohibited inside the gulf due to an official ban, established in 1966, as a conservational measure. However, artisanal fishing with bottoms nets and baited creels is still allowed, with seasonal closures in June-August for bottom nets and May-July for baited creels [44].…”

The Effect of Temperature on the Physiological Condition and Immune-Capacity of European Lobsters (Homarus gammarus) During Long-Term Starvation

“…Four main types of cells in the hepatopancreas have been described in the literature, namely embryonic cells (Ecells), resorptive cells (R-cells) involved in the uptake and storage of nutrients, fibrillar cells (F-cells) involved in the release of digestive enzymes for extracellular digestions and the blisterlike cells (B-cells) which contain a single large vacuole and are responsible for intracellular digestion (Barker and Gibson, 1977;Brunet and Mazza, 1994). Previous studies have reported that long periods of natural or imposed starvation induce changes particularly in the R-cells (fewer lipid droplets; Berillis et al, 2013;Cervellione et al, 2017a;Stathopoulou et al, 2017), a lower number of enzyme producing F-cells, which reduces the hepatopancreas digestive capacity (Papathanassiou and King, 1984;Icely and Nott, 1992) and hypertrophy of B-cells with enlarged vesicles (Sacristan et al, 2016). In this study, fasting produced a decrease in the number and the area of F-cells (release of digestive enzymes for extracellular digestion) and an increase in the vacuole area of B-cells (intracellular digestion).…”

Ecological Assessment of Fishery Communities in an Otter-Trawl-Restricted, Semi-Enclosed Gulf in Greece

“…1 Royal Decree 50/67) [9]. However, artisanal fishing with bottoms nets and baited creels is still allowed, with seasonal closures in June-August for bottom nets and May-July for baited creels [10].…”