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- Improving the fitness of Holothuria arguinensis larvae through different microalgae dietsPublication . Dominguez-Godino, Jorge A.; Gonzalez-Wanguemert, MercedesDevelopment and design of adequate feeding protocols on sea cucumber larvae are necessary for improvements on larvae growth, survival and production of competent juveniles. This work assessed the Holothuria arguinensis larvae growth and survival, fed with three different single microalgae diets of Chaetoceros calcitrans, Isochrysis galbana and Tetraselmis chui, and two microalgae diets based on a combination of C. calcitrans and T. chuii (C:T 1:1) and C. calcitrans, T. chuii and I. galbana (C:T:I 1:1:1) during 2 months. Holothuria arguinensis larvae fed with T:C:I, showed higher survival and larger larval and stomach sizes than the ones fed with the other diets. Comparing the results obtained from the single diets, H. arguinensis larvae fed with I. galbana grew and survived better during the first 5 days. However, higher growth was obtained on the larvae fed with C. calcitrans from day 5 to day 12 since this day, larvae fed with T. chuii showed the largest size. These results could be related to the different microalgae size and morphology, in addition to the nutritional value of the different microalgae used. However, no competent larvae that metamorphosed into doliolaria were obtained during this experiment. The tanks used were transparent, which could be causing light stress to the larvae, since competent larvae were obtained in opaque production tanks in our aquaculture installations during the same time period. The combined diet of C. calcitrans, T. chuii and I. galbana (C:T:I) could improve the growth and larvae competency of H. arguinensis.
- 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.
- Seagrass debris as potential food source to enhance Holothuria arguinensis' growth in aquaculturePublication . Dominguez Godino, Jorge Antonio; Santos, Tamara; H., Pereira; Custódio, Luísa; Gonzalez-Wanguemert, MercedesHolothuria arguinensis aquaculture started to be developed in 2014, being the first sea cucumber species from Europe. However, some aspects of its aquaculture biotechnology, such diets, need to be assessed. This work aimed to evaluate seagrass debris of Zostera noltii and Cymodocea nodosa as food source for broodstock maintenance in tanks, during breeding periods. The given feed rations per tank were calculated as the 30% of the total sea cucumber biomass in each tank and reviewed each week. Then, feed rations of seagrass and sediment were calculated from this value, according to the following percentages: 40% sediment, 15% Z. noltii, 40% Z. noltii, 15% C. nodosa and 40% C. nodosa. H. arguinensis growth, feeding rate and nutritional value were assessed under these diets. H. arguinensis fed with 40% of Z. noltii showed the highest growth (specific growth rate = 0.09 +/- 0.06%/day, absolute growth rate = 0.11 +/- 0.07 g/day) increasing their final weight in 5.86 +/- 3.57% in 57 days. However, the individuals fed with C. nodosa showed a negative growth. H. arguinensis showed a reduction in its feeding rate as the organic matter content in the diets increased. H. arguinensis did not show any important change on proximate composition, protein, lipid, mineral contents and fatty acids profile among the feeding groups, or in comparison with the individuals collected from wild habitat. Therefore, H. arguinensis could be fed with Z. noltii debris during tanks maintenance along breeding period, ensuring its growth and maintaining its nutritional profile.
- Compounded perturbations in coastal areas: contrasting responses to nutrient enrichment and the regime of storm-related disturbance depend on life-history traitsPublication . Bertocci, Iacopo; DOMINGUEZ GODINO, JORGE ANTONIO; Freitas, Cristiano; Incera, Monica; Bio, Ana; Dominguez, Rula1. Natural systems are exposed to compounded perturbations, whose changes in temporal variance can be as important as those in mean intensity for shaping the structure of assemblages. Specifically, climate-related physical disturbances and nutrient inputs due to natural and/or anthropogenic activities occur concomitantly, but experimental tests of the simultaneous effects of changes in the regime of more than one perturbation are generally lacking. Filling this gap is the key to understand ecological responses of natural assemblages to climate-related change in the intensity and temporal patterning of physical disturbance combined with other global stressors. 2. Responses to factorial manipulations of nutrient enrichment, mean intensity and temporal variability in storm-like mechanical disturbance were examined, using benthic assemblages of tide-pools as model system. 3. Response variables were mean abundance values and temporal variances of taxa with different life-traits. Consistent negative effects of disturbance intensity were observed for the mean cover of long-living taxa (algal canopies and the polychaete Sabellaria alveolata), whose temporal fluctuations were also reduced by more severe mechanical stress. More resilient taxa (ephemeral algae, mostly green of the genus Ulva) increased under enriched conditions, particularly when low-intensity events were irregularly applied over time. Opposite effects of disturbance intensity depending on nutrient availability occurred on filamentous algae (e.g. red of the genus Ceramium). This was probably due to the fact that, although nutrient enrichment stimulated the abundance of both algal groups, when this condition was combined with relatively mild physical disturbance the competitively superior ephemeral green algae tended to become dominant over filamentous red algae. The same did not occur under high intensity of disturbance since it likely damaged large, foliose fronds of Ulva-like forms more than small, filamentous fronds of Ceramium-like forms. Grazers were positively affected by nutrients, likely responding indirectly to more food available. 4. A direct relationship between the mean abundance of most organisms and their temporal fluctuations was documented. However, all organisms persisted throughout the study, even under experimental conditions associated to the largest temporal variation in their abundance, likely due to their ability to resist to/quickly recover from, the applied perturbations. Therefore, in systems with great recovery abilities of dominant organisms (e.g. rocky intertidal, grasslands), effects of traits of the regime of disturbance and nutrient enrichment may modulate the fluctuations of populations not through the elimination and substitution of species, but through changes in relative abundances of the same species. This contrasts with the theory that temporal variation in abundance would be directly related to the risk of local extinction. Present findings enable more accurate predictions of the consequences of climatic and non-climatic scenarios on the biodiversity of marine and terrestrial systems sharing analogous functional traits of organisms. Future more intense physical disturbances are expected to exert negative effects on slow-growing/recovering species (e.g. habitat-formers) irrespectively of the temporal patterning of the same disturbances and nutrient inputs. On the contrary, more resistant species (e.g. encrusting algae on rocky shores or below-ground vegetation in grasslands) are expected to benefit from intense physical disturbance. Species whose abundance is more directly related to the availability of nutrients (e.g. filamentous and ephemeral algae or herbs) are expected to generally increase under enriched conditions, but their ability to eventually become dominant would depend on their ability to grow fast and attain cover large enough to overwhelm any possible control of concomitant disturbance intensity on their abundance. If, such as in the present examined system, virtually all organisms can persist, over the temporal scale of the experiment, under any combination of physical disturbance and nutrient availability, the resulting overall diversity is not predicted to change drastically. Nevertheless, low-intensity events evenly distributed and high-intensity events irregularly distributed appear as the conditions supporting the highest richness of taxa, independently of the availability of nutrients.
- 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.