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- Habitat associations and seasonal abundance patterns of the sea cucumber Holothuria arguinensis at Ria Formosa coastal lagoon (South Portugal)Publication . DOMINGUEZ GODINO, JORGE ANTONIO; Gonzalez-Wanguemert, MercedesSea cucumbers have an important economic value and high demand. Despite that, there is a lack of knowledge about their biology, ecology and habitat distribution patterns, which is very important for sea cucumber stock management, establishment and sizing of no-take zones, restocking actions and selection of grow-out areas. This work aimed to determine the density, abundance and habitat associations of Holothuria arguinensis for a better understanding of its distribution along the coastal lagoon Ria Formosa and to select suitable areas for grow-out. In the duration of a year, monthly visual censuses were performed in two locations at Ria Formosa along the intertidal zone. The number and length of H. arguinensis ' individuals found were registered, and the coverage of algae and seagrass was estimated. It was found that H. arguinensis was distributed along the lower intertidal zone, linked to Zostera noltii meadows on muddy and sandy bottoms. These areas showed the densest population and the largest sizes of H. arguinensis. However, during the warmer months, H. arguinensis seemed to migrate to deeper waters in the channels, to avoid exposition to high temperatures and solar/UV irradiance during low tides. Areas located in the lower intertidal zone with Z. noltii meadows on sand-muddy bottoms should be selected for H. arguinensis grow-out sites.
- Epidemiology of skin ulceration disease in wild sea cucumber Holothuria arguinensis, a new aquaculture target speciesPublication . Cánovas, F.; DOMINGUEZ GODINO, JORGE ANTONIO; Gonzalez-Wanguemert, MercedesInterest in wildlife epidemiology has increased in recent years. The control of diseases is critical for the survival of natural populations of economically valuable species. The present study is the first investigation of the etiology and epidemiology of skin ulceration disease in the sea cucumber Holothuria arguinensis, a new target species for fisheries and aquaculture in Europe. Bacterial cultures and molecular techniques were used to characterize this disease in animals collected during a survey across Ria Formosa Natural Park coastal lagoon in southern Portugal. Vibrio gigantis and V. crassostreae, which were both originally identified as disease agents in cultured oysters, were the most commonly isolated species of bacteria. Given that both sampling areas from which symptomatic H. arguinensis were collected were close to open oyster aquaculture facilities, this raises the possibility of an opportunistic infection, perhaps secondary to a decreased immune response caused by biotic or abiotic factors. An increase in prevalence of skin ulceration disease during the warmer season suggests that solar radiation and desiccation due to air exposure during low tide could be a cause of abiotic stress in the lagoon. Distributions of abundance and sizes of H. arguinensis in affected areas showed highest morbidity rates in adults. High fishery pressures throughout the study period could also cause elevations in prevalence and incidence rate of this disease. Skin ulcerative disease is endemic in this coastal lagoon. Disease monitoring is thus essential for the development of a conservation program to ensure the sustainability of fisheries and protection of natural resources.
- Assessment of Holothuria arguinensis feeding rate, growth and absorption efficiency under aquaculture conditionsPublication . DOMINGUEZ GODINO, JORGE ANTONIO; Gonzalez-Wanguemert, MercedesHolothuria arguinensis is a potential species for sea cucumber aquaculture in Europe. In a first experiment, feeding rate (FR), growth, absorption efficiency (AE) and survival of adults (135.01 +/- 10.87g eviscerated weight) were assessed under sediment tank conditions. In a second experiment, the feasibility to use sea bream (Sparus aurata) biodeposits as a food source was studied for adults (168.69 +/- 14.59g eviscerated weight). Individuals in the first experiment showed an increase of weight (specific growth rate (SGR)=0.2% d(-1)), positive FRs and mean value of AE close to 80% with a mean organic matter content of 90.07 +/- 11.5mg/g in the offered sediment. Sea cucumbers fed with fish biodeposits showed a reduction of weight (SGR<-0.14%d(-1)), low FRs and negative values of AE. The influence of low salinity and temperature during experiments should be considered to explain these results. Indeed, sea cucumbers can be affected by a decrease of these parameters during winter months resulting in a period of inactivity.