Spatial ecology of Norway lobster Nephrops norvegicus in Mediterranean deep-water environments: implications for designing no-take marine reserves

2021 ◽  
Author(s):  
M Vigo ◽  
J Navarro ◽  
I Masmitja ◽  
J Aguzzi ◽  
JA García ◽  
...  
Keyword(s):  
Deep Water ◽  
Spatial Ecology ◽  
Marine Reserves ◽  
Nephrops Norvegicus ◽  
Norway Lobster

scholarly journals Spatiotemporal abundance pattern of deep-water rose shrimp, Parapenaeus longirostris, and Norway lobster, Nephrops norvegicus, in European Mediterranean waters

2020 ◽  
Vol 83 (S1) ◽  
pp. 71 ◽  
Author(s):  
Mario Sbrana ◽  
Walter Zupa ◽  
Alessandro Ligas ◽  
Francesca Capezzuto ◽  
Archontia Chatzispyrou ◽  
...  
Keyword(s):  
Deep Water ◽  
Life History Traits ◽  
Environmental Drivers ◽  
Nephrops Norvegicus ◽  
Abundance Pattern ◽  
Norway Lobster ◽  
Levantine Basin ◽  
Parapenaeus Longirostris ◽  
Living Species ◽  
Rates Of Growth

The main characteristics concerning the distribution of two of the most important decapod crustaceans of commercial interest in the Mediterranean Sea, the deep-water rose shrimp, Parapenaeus longirostris, and the Norway lobster, Nephrops norvegicus, are studied in the European Mediterranean waters. The study is based on data collected under the MEDITS trawl surveys from 1994 to 2015 from the Gibraltar Straits to the northeastern Levantine Basin (Cyprus waters). The observed differences can be interpreted as different responses to environmental drivers related to the differing life history traits of the two species. In fact, N. norvegicus is a long-living, benthic burrowing species with low growth and mortality rates, while P. longirostris is an epibenthic, short-living species characterized by higher rates of growth and mortality.

Depth related variation in the structure and functioning of the compound eye of the Norway lobster Nephrops norvegicus

1990 ◽  
Vol 70 (2) ◽  
pp. 343-355 ◽  
Author(s):  
E. Gaten ◽  
P.M.J. Shelton ◽  
C.J. Chapman ◽  
A.M. Shanks
Keyword(s):  
Deep Water ◽  
Dark Adaptation ◽  
Compound Eye ◽  
Light Exposure ◽  
Retinula Cell ◽  
Nephrops Norvegicus ◽  
Norway Lobster ◽  
Photon Fluence Rate ◽  
Screening Pigment ◽  
Photon Fluence

The mobility and quantity of retinula cell proximal screening pigment, and the liability of the eyes to light-induced damage, were investigated in the Norway lobster, Nephrops norvegicus (L.), obtained from three separate populations from depths of 18, 75, and 135 m.During the morning after capture, the migration of the proximal pigment in response to the onset of illumination below the threshold for damage varied between the three populations. In the eyes of deep water N. norvegicus, the proximal screening pigment was located close to or below the basement membrane when dark-adapted and rose to a position midway up the rhabdoms when light-adapted. In the dark-adapted N. norvegicus from shallow water the proximal pigment was located more distally than in eyes of deep water animals. After the onset of illumination, the pigment migrated distally to completely cover the rhabdoms. The amount of retinula cell proximal screening pigment was found to decrease linearly with depth.When dark-adapted individuals from each depth were exposed to light a positive correlation was obtained between the photon fluence rate (PER) and the proportion of the retina damaged. For a given light exposure the amount of damage was highest in animals from deeper water. The PFR causing 25% damage was approximately 1 log unit higher in animals from 18 m compared to those from 135 m.The amount of damage varied with the delay between capture of the animals and exposure to light. When exposed 2 h after capture significant differences between depths were seen but the results were influenced by the incomplete dark adaptation of some specimens.

scholarly journals Ovary resorption in the Norway lobster (Nephrops norvegicus) and its possible causes with special reference to sperm storage

2020 ◽  
Vol 74 (1) ◽  
Author(s):  
Carola Becker ◽  
Jaimie T. A. Dick ◽  
E. Mánus Cunningham ◽  
Mathieu Lundy ◽  
Ewen Bell ◽  
...  
Keyword(s):  
North Sea ◽  
Demographic Data ◽  
Irish Sea ◽  
Natural Phenomenon ◽  
Nephrops Norvegicus ◽  
North East ◽  
The North ◽  
Norway Lobster ◽  
The North Sea ◽  
Reproductive Cycles

Abstract The Norway lobster, Nephrops norvegicus, is an important fisheries species in the North-East Atlantic area. In some circumstances, mature females of Nephrops norvegicus can resorb their ovary rather than completing spawning, but the implications of this phenomenon to reproductive biology and fisheries sustainability are not known. To understand after effects of ovary resorption, we studied long-term demographic data sets (1994–2017) collected from the western Irish Sea and the North Sea. Our considerations focused on potential correlations among the frequency of resorption, female insemination, and body size of resorbing females. Resorption was continuously rare in the western Irish Sea (less than 1%); whereas much higher rates with considerable year-to-year variation were observed in the North Sea (mean 9%). Resorption started in autumn after the spawning season (summer) had passed. The frequency stayed high throughout winter and declined again in spring. As sperm limitation can occur in male-biased fisheries, we expected a lack of insemination could be responsible for resorption, but affected females were indeed inseminated. Resorbing females were significantly larger than other sexually mature females in the North Sea, but the opposite trend was observed in the western Irish Sea. It is therefore possible that other, environmental factors or seasonal shifts, may trigger females to resorb their ovaries instead of spawning. Resorption may as well represent a natural phenomenon allowing flexibility in the periodicity of growth and reproduction. In this sense, observations of annual versus biennial reproductive cycles in different regions may be closely linked to the phenomenon of ovary resorption.

scholarly journals Heterozygosity fitness correlations and generation interval of the Norway lobster in the Aegean Sea, eastern Mediterranean

2019 ◽  
Vol 26 (1) ◽  
Author(s):  
Georgios A. Gkafas ◽  
Marianthi Hatziioannou ◽  
Emmanouil E. Malandrakis ◽  
Costas S. Tsigenopoulos ◽  
Ioannis T. Karapanagiotidis ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Recruitment Strategy ◽  
Breeding Period ◽  
Nephrops Norvegicus ◽  
Norway Lobster ◽  
Genetic Impact ◽  
Potential Population ◽  
High Gene ◽  
Local Residents

Abstract Background Comprehensively detailed information on population dynamics for benthic species is crucial since potential admixture of individuals could shift the genetic subdivision and age structure during a full breeding period. The apparent genetic impact of the potential recruitment strategy of Norway lobster Nephrops norvegicus is still under research. For this reason the present study was focused on genetic variation of the species over a given continuous year period in a semi-enclosed gulf of the Aegean Sea. Results Analyses revealed that the relative smaller size class in females and the apparent faster growth of males may represent a key-role differential strategy for the two sexes, whereas females tend to mature slower. Heterozygosity fitness correlations (HFCs) showed substantially significant associations suggesting that inbreeding depression for females and outbreeding depression for males are the proximate fitness mechanisms, respectively. Conclusions Nephrops norvegicus uniformal genetic composition (background of high gene flow), could be attributed to potential population recolonization, due to a hypothesized passive larval movement from deeper waters, which may suggest that some offspring of local residents and potential male non-breeders from other regions admixture randomly.

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