Papers by Alhambra Cubillo
Aquaculture, 2016
The performance of deposit feeders in integrated multi-trophic aquaculture (IMTA) was analysed th... more The performance of deposit feeders in integrated multi-trophic aquaculture (IMTA) was analysed through the application of mathematical models. Loading of organic particulates to the benthos as a result of finfish cage culture and shellfish suspended culture was analysed by means of a deposition model (ORGANIX), and an individual model for growth and environmental effects was developed for the California sea cucumber Parastichopus californicus. Following validation, the model was combined with existing models for finfish, shellfish, and macroalgae into a framework for simulation of IMTA interactions at the local scale. Several scenarios for different culture combinations and densities were simulated using the Farm Aquaculture Resource Management (FARM) model, using a layout which reflects typical stocking densities and spatial occupation in Europe and North America. The model allows an analysis of the different sources and fate of particulate organic matter associated with distinct culture groups. Our results illustrate the production enhancement for deposit feeders cultivated below both finfish (600%) and shellfish (150%). Furthermore, sea cucumbers are responsible for a significant removal of the particulate organic carbon loading to the bottom, reducing the gross load by up to 86% for finfish culture and 99% for shellfish culture. The role of cultivated seaweeds in reducing the dissolved nitrogen concentration in the farm area was also examined-no significant reduction in ambient nutrient concentration was observed, but the added nitrogen provides a clear stimulus (22% increase) to kelp production. By contrast, shellfish grown in suspended culture in the vicinity of finfish cages show very little change in individual growth or harvestable biomass. This work helps to analyse the ecological and economic potential of various forms of IMTA, and the role of co-cultivation in direct extraction and re-use of materials and energy at both the local (farm) and system (bay, estuary) scales. Statement of relevance: Analysis of the ecological and economic potential of various forms of IMTA, and the relevance of co-cultivation in direct extraction and re-use of materials and energy at both the local (farm) and system (bay, estuary) scales. FARM model framework applied to understand the roles of suspended bivalve culture and benthic deposit-feeder culture in mitigating the negative externalities of finfish culture.
Reviews in Aquaculture, 2015
The fast rise of aquaculture practices during the last decades has increased the need of adopting... more The fast rise of aquaculture practices during the last decades has increased the need of adopting culture strategies to optimize production and guarantee the sustainability of the sector. This study aimed to provide a management tool to help mussel farmers identify optimal culture strategies and use production inputs efficiently. For this purpose, we evaluated the productivity and efficiency of different stocking densities and culture durations by the joint application of parametric and nonparametric frontier analysis at the farm scale. The translog production function outperformed the Cobb–Douglas model currently applied in most farm‐scale frontier analyses. This model estimates that the optimal culture density is ca. 700 ind m−1, given that at lower densities, efficiency decreases (under‐usage of available space) and mussel quality did not improve, and at higher densities, mortality and dislodgements from the ropes led to economic losses. This work also showed that marginal analys...
168 páginasEsta tesis se ha realizado bajo la financiación del contrato-proyecto PROINSA-CSIC 200... more 168 páginasEsta tesis se ha realizado bajo la financiación del contrato-proyecto PROINSA-CSIC 20061089 y 0704101100001 y de los proyectos de la Xunta de Galicia PGIDIT06RMA018E y PGIDIT09MMA038EPeer reviewe
Crowding conditions in bivalve populations cause intraspecific competition processes, resulting i... more Crowding conditions in bivalve populations cause intraspecific competition processes, resulting in individual growth reduction and, in extreme cases, density dependent mortality. In aquaculture, where density is usually maximized to obtain a greater commercial yield, this fact leads to a decrease in the total biomass of the ropes and to an increased dislodgement of mussels, causing losses in production with the subsequent benefit reduction. Commercial farms provide an ideal scenario for studying the effect of density on mussel growth in suspended culture systems. In this study, sequential monitoring of several Mytilus galloprovincialis populations grown along a cultivation density gradient was conducted. Ropes cultured at different densities (220, 370, 500, 570, 700, 800 and 1150 ind/m) were hanged from a commercial raft and biomass and density values were monitored monthly over the second phase of traditional culture in Galicia, from thinning-out to harvest (April to October 2008)....
Reviews in Aquaculture, 2013
The main drawback of the traditional self-thinning model is how time is handled. Selfthinning (ST... more The main drawback of the traditional self-thinning model is how time is handled. Selfthinning (ST) has been formally recognized as a dynamic process, while the current ST models have not included the temporal effect. This restricts the analysis to the average competitive behavior of the population and produces a biased estimation of the selfthinning parameters. In this study we extend the dynamic ST model introduced by Roderick and Barnes (2004) to the analysis of multilayered sessile animal populations. For this purpose, we incorporate the number of layers and the density per layer into the dynamical approach. The performance of the dynamic model was checked and compared with the classical ST model through the analysis of mussel populations grown at different density treatments. Unlike the traditional model, the dynamical approach detected the effect of culture density on the competitive behavior of individuals and allowed to analyze the temporal evolution of intraspecific competition by estimating the ST exponent trajectory. Moreover, this approach provided an ecological interpretation of any possible value of the ST exponent. Thus, our results support the use of the dynamic model in the analysis of self-thinning in sessile animal multilayered populations. The estimation of the ST exponent trajectory reflects the dynamic nature of the ST process, providing a more realistic description of population dynamics than the traditional model.
Ecosphere, 2012
Self‐thinning (ST) models have been widely used in the last decades to describe population dynami... more Self‐thinning (ST) models have been widely used in the last decades to describe population dynamics under intraspecific competition in plant and animal communities. Nevertheless, their applicability in animal populations is subjected to the appropriate inclusion of space occupancy and energy requirements. Specifically, the disposition of gregarious sessile animals in complex matrices hampers the application of classical ST models. This paper reviews the self‐thinning models, regression methods (central tendency and frontier techniques) and discrimination criteria currently applied for gregarious sessile species through application to the analysis of mussel populations (Mytilus galloprovincialis) grown in suspended culture. In addition, we propose to model the temporal evolution of site occupancy in the stochastic frontier function (SFF). Our results confirm that the number of layers should be included in the classical bidimensional ST model for the analysis of multilayered populatio...
Aquaculture Research, 2013
ABSTRACT Fish farming releases extensive amounts of particulate organic waste that can be exploit... more ABSTRACT Fish farming releases extensive amounts of particulate organic waste that can be exploited by bivalves in integrated culture. We tested if mussels Mytilus galloprovincialis cultured at two depths (1 and 6 m) in a raft, moored 170 m from a fish farm had greater growth than bivalves held 550 m from the fish cages. Mussel growth was monitored monthly, covering the second phase of the culture, from thinning- out to harvest (March to November 2011). We also studied if fish solid and dissolved nutrients increased the organic content of the seston and chlorophyll-a levels near the fish cages through weekly samples. Results showed no differences in seston, chlorophyll and physiochemical characteristics of the water among rafts. Maximum growth and Condition Index (CI) occurred during spring– summer (April–August), when mussels had access to greater food quality and quantity. Mussels cultivated close to the cages showed similar shell length, weight and CI compared with mussels distant from the fish farm. Average shell length, meat dry weight and CI at harvest were 76.31 mm, 2.51 g and 23%. Bivalves cultured distant from the fish cages displayed 26% higher biomass than the other raft at the end of the experiment. Differences in biomass were explained by the significantly higher recruitment of mussel seed observed at the raft distant from the fish cages from June to November. The lack of a significant enhancement in growth of the bivalves cultured next to finfish is discussed.
Aquaculture, 2012
Crowding conditions in bivalve populations cause intraspecific competition processes, resulting i... more Crowding conditions in bivalve populations cause intraspecific competition processes, resulting in individual growth reduction. In aquaculture, density is usually maximized to obtain a greater commercial yield. Commercial farms provide an ideal scenario for studying the effect of density on mussel growth in suspended culture systems. In this study, different growth indicators for Mytilus galloprovincialis (growth rates, length and weight growth curves and size frequency distributions) were measured along a cultivation density gradient. Ropes cultured at different densities (220, 370, 500, 570, 700, 800 and 1150 ind/m) were hanged from a commercial raft and growth indicators were monitored monthly over the second phase of traditional culture in Galicia, from thinning-out to harvest (April to October 2008). A negative effect of density on individual growth was observed. Individuals cultured at lower densities presented higher growth rates and consequently reached greater weight and length values at the end of the experimental period than those cultured at higher densities. Differences in growth related to the cultivation density may suggest differences in intraspecific competition for limiting resources (space/food). Effects of density on growth started after 4 months of culture (August) when individuals reached sizes around 66 ± 1.3 mm. The increase in size of individuals in a population implies an increment of their food and space requirements, which in turn intensifies intraspecific competition. This fact should be considered in aquaculture management, since higher densities could be supported without effects on growth performance if cultured mussels are limited to a lower size.
Aquaculture, 2012
Bivalve molluscs are characterized by high morphological plasticity in response to variations in ... more Bivalve molluscs are characterized by high morphological plasticity in response to variations in local environmental conditions. In the present study, we evaluate this capacity in the mussel Mytilus galloprovincialis with regard to intra-specific competition caused by cultivation density. Suspended cultivation ropes at different initial densities (220, 370, 500, 570, 800 and 1150 individuals per meter of rope) were placed on a raft in the Ría Ares-Betanzos, following standard cultivation techniques. From May to October, covering the period from thinning out to harvest, various morphological indicators (length/width, length/height and height/width ratios) and allometric relationships (Volume-Length and Projected area-Length) in addition to energy distribution (dry tissue weight/dry valve weight) were analyzed. Differences in morphological indicators due to cultivation density were observed while no influence on the energy distribution was detected. From the second cultivation month (June), a decrease was recorded in the length/height ratio of individuals due to cultivation density. Similarly, there was also a decrease in the length/width ratio, although this decrease only became statistically significant from September. In addition, the allometric relationships studied (Volume-Length and Projected area-Length) suggested asymmetric competition processes. Differences in volume or projected area between densities were only detected at the end of the experimental culture (October) and only in the smaller individuals. These morphological adaptations can be understood as a strategy to mitigate the effects of intra-specific competition, palliating the consequences of physical interference at high densities.
Journal of Sea Research, 2015
Population dynamics on mussels growing on suspended culture depend mainly on the balance 12 of th... more Population dynamics on mussels growing on suspended culture depend mainly on the balance 12 of three processes: mortality and/or dislodgements, recruitment and growth. The negative 13 effect of overcrowding on mussels growth and survival has been widely studied. Some studies 14 have also addressed the effect of population size on recruitment on bottom beds. This work 15 analyzes the effect of stocking density on mussel growth, survival and seed settlement, and 16 the post-settlement interaction between adults and recruits in suspended culture. Our results 17 show a trade-off between competition for resources and the risk of great settlements in adult 18 mussel populations. Intracohort competition increases with stocking density, leading to mussel 19 losses and growth declines along culture, while seed settlement, which leads to intercohort 20 competition, is higher at moderate stocking densities. On the other hand, the asymmetric 21 competition for resources between adults and settlers can lead to post-settlement mortality 22 and dislodgments and reduce the growth of recruits. 23
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Papers by Alhambra Cubillo