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Beckensteiner, J., Kaplan, D. M., & Scheld, A. M. (2020). Barriers to Eastern Oyster Aquaculture Expansion in Virginia. Front. Mar. Sci., 7, 53.
Résumé: The eastern oyster once provided major societal and ecosystem benefits, but these benefits have been threatened in recent decades by large declines in oyster harvests. In many areas, recovery of oyster aquaculture faces significant societal opposition and spatial constraints limiting its ability to meet expectations regarding future food needs and provision of ecosystem services. In Virginia, oyster aquaculture has begun to expand, concurrent with an increase in subaqueous leased areas (over 130,000 acres of grounds are currently leased). Though private leases must in theory be used for oyster production, in practice, they can be held for other reasons, such as speculation or intentional exclusion of others. These factors have led to large variation over time and space in the use of leases in lower Chesapeake Bay; and privately leased grounds are now thought to be underutilized for oyster production. This research examined potential barriers to expansion of oyster aquaculture in Virginia. We first evaluated if a lack of space was limiting industry expansion and quantified temporal and spatial trends in the use and productivity of leases. Then, differences in used and non-used leases were investigated in relation to variables thought to be related to “not in my backyard” attitudes, congestion, speculation, local economic and environmental conditions. Finally, the performance of the Virginia leasing system was compared with those in other states along the U.S. East and Gulf Coasts. We found limited evidence for spatial constraints on aquaculture leasing, but strong evidence for social and regulatory inefficiencies. Although rates of lease use increased from 2006 to 2016, only 33% of leases were ever used for oyster production and about 63% of leaseholders reported no commercial harvests. Non-used leases tended to be smaller, and were found in more populated, high-income regions, consistent with both speculative and exclusionary uses. Virginia had the second lowest level of total production of cultured oysters per leased acre among the states on the East and Gulf Coasts of the United States. These results indicate that there is room for oyster aquaculture expansion in Virginia if societal, regulatory, and economic barriers can be reduced or if existing leased areas are used more efficiently.
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Espinosa, F., & Rivera-Ingraham, G. A. (2016). Subcellular evidences of redox imbalance in well-established populations of an endangered limpet. Reasons for alarm? Mar. Pollut. Bull., 109(1), 72–80.
Résumé: Intertidal species are more vulnerable to anthropogenic disturbances than others inhabiting subtidal and offshore habitats. Coastal development frequently results in trace-metal pollution. For endangered species such as Patella ferruginea it can be a high risk that leads local populations to extinction. Three localities were surveyed, one within a natural and unpolluted area and the other two within the harbor of Ceuta (Strait of Gibraltar), on breakwaters outside and inside. The specimens collected inside the harbor reached 3-fold higher Hg content than for those incoming from the natural area. PERMANOVA test indicated that metal composition of the specimens from inside the harbor was different from the rest. In addition, evidence of cell damage was detected in the specimens from the harbor area. This highlights the urgency of undertaking a physiological evaluation of some of the most vulnerable populations, establishing eco-physiological protocols for monitoring and managing populations settled on artificial substrata. (C) 2016 Elsevier Ltd. All rights reserved.
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Roques, C., Grousset, E., Troussellier, M., Hermet, S., Le Carrer, J., Sar, C., et al. (2020). A trade-off between mucocytes and bacteriocytes inLoripes orbiculatusgills (Bivalvia, Lucinidae): a mixotrophic adaptation to seasonality and reproductive status in a symbiotic species? Mar. Biol., 167(10), 154.
Résumé: In this study, we investigated the composition of the gill tissue relative to the reproductive status of the lucinid clamLoripes orbiculatus(sensus Poli, 1791) according to seasonal as well as biological parameters to provide insights into the physiological variability of this symbiotic bivalve. Temporal variation in population density was also studied. The species was investigated inZostera noltiiseagrass beds in the Thau lagoon (43 degrees 26 ' 52.27 '' N, 3 degrees 39 ' 6.25 '' E) in the south of France in a monthly sampling study from May 2013 to July 2015. A total of 257 individual adults of different sizes were analysed according to water temperature and salinity variations. The findings revealed a very stableLoripesdensity over time, with one single reproductive period during late spring/early summer. We also found that bacteriocytes and mucocytes in the gills were negatively correlated and highly variable in their respective proportions. Bacteriocytes remained dominant during cold periods, whereas mucocytes appeared mainly in the gills of large individuals when the water temperature increased in the spring. As mucocytes were also related with gonadal maturation, we hypothesize that these may allow the host to increase the proportion of heterotrophy in its nutrition during spring primary production to face the metabolic demands required for reproduction. It is possible that mucocytes may also be involved in host immunity.
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