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Insights into Aquaculture’s Potential of Polychaetes

Polychaetes, generally are marine annelid worms that have gained popularity owing to their use as baits both for recreational and professional fishing purposes. In addition, it can also contribute to aquaculture diversification. Though polychaete culture has been feasible and commercially attempted too, managing polychaete fisheries has progressed only in few countries around the world. Those countries with no marine polychaetes production either depend upon wild harvest or imports. An in-depth study is needed to provide a better understanding of the nutritional requirements and reproduction of some species. Nevertheless, new technical improvements that can lead to significant progress in productivity and give fresh momentum to the polychaete production have been demonstrated. Amongst the marine worm species, a few were recognized as good candidates for integrated multitrophic aquaculture.  Within this aspect, the development of rearing techniques and grow-out procedures are the central points. This will allow the culture of new polychaetes, possible in polyculture systems that can enhance aquaculture sustainability, reduce environmental threat and increase earnings. Considerable environmental benefits might be gained by increasing bait farming and reducing bait-digging activity. Moreover, many anglers would prefer to purchase cultured bait rather than dig their own, provided the supplies were of high quality and priced advantageously with respect to some of the worms collected from the wild. Additionally, some worms are also regarded as one of the most important components in order to maintain a thriving sand bed. They are excellent scavengers and detritus consumers. Their activity turns over the upper layers of aquarium sand beds, working detritus into the sand, thereby preventing clumping. Furthermore, the demand for polychaetes has increased as a result of their use to feed other species in aquaculture as it ensures adequate nutrition for reared broodstock. Last but not the least, polychaetes are also extensively used for research purposes, as model animals, for instance in reproduction, ecotoxicology, bioremediation, and environmental monitoring studies. Substantial work focused on the main technical improvements and advances have been made in areas as varied as polychaetes’ aquaculture potential, reared species, main species used worldwide, highlights biological and ecological concerns, important challenges and recommendations.

For more information please refer:Insight into aquaculture's potential of marine annelid worms and ecological concerns: a review

Polychaetes and their potential use in aquaculture

Use of blue mussels (Mytilus edulis and Mytilus trossulus) for the removal of organic particulates from Atlantic salmon cage in an open-water IMTA system.

The extraction of organic matter from intensive aquaculture systems is one of the main concerns to minimize the environmental impact of this activity. In the specific case of IMTA systems, various types of organisms are used to successfully perform this task. However, knowing the percentages of organic matter removal of the different extraction species is essential for the dimensioning and evaluation of IMTA systems. For this purpose, researches in the St. Andrews Biological Station in St. Andrews, Canada, carried out laboratory and field experiments to determine the absorption efficiency of the blue mussels and its potential as organic matter extractive species in IMTA. In the laboratory the diets tested were: two algal diets (a commercial spat and a diatom formula), two salmon farm diets and salmon feces, meanwhile in the field test the total particulate matter from the salmon cages was tested.

The absorption efficiency obtained for the different kind of diets were 87, 81, 90, 86 and 54%, for commercial spat formula, commercial diatom diet, salmon feed, salmon feces and total particulate matter from salmon cages. These results recommend that the blue mussels have the capacity of absorbing those waste produced from the salmon cages and represent optimal candidates as organic matter extractive species in IMTA systems with salmon.

For more details, see Reid et al. (2010) Absorption efficiency of blue mussels (Mytilus edulis and M. trossulus) feeding on Atlantic salmon (Salmo salar) feed and fecal particulates: Implications for integrated multi-trophic aquaculture. Aquaculture 299, 165-169.

The potential of the macroalgae Gracilaria lemaneiformis as a biofiltrator of dissolved nutrients in Integrated Multi-Trophic Aquaculture (IMTA)

In recent years, the use of seaweed for the bioremediation of aquaculture effluents has increased. Several studies have shown the capacity of nutrient removal of different species of macroalgae and their potential for the integration in aquaculture systems as inorganic dissolved nutrients extractors. In this sense, a research team from China evaluated the nutrient uptake rate and a nutrient reduction efficiency of ammonium and phosphorus from scallop (Chlamys farreri) excretion by the seaweed Gracilaria lemaneiformis cultured in IMTA system in North China. The study was carried out in the Marine Aquaculture Laboratory of Institute of Oceanology., in Qingdao, for three weeks. Four macroalgae density were tested: 69.3 (T1), 139 (T2), 263 (T3) and 347 g m-3 (T4) meanwhile the stock density of scallops was the same in all treatments (409.9 g m-3). At the end of the experiment, the nutrient uptake rate and nutrient reduction efficiency (ammonium and phosphorus) were estimated.


Experimental design seaweed and scallops IMTA

IMTA system used in the present study


The nutrient uptake rate and nutrient reduction efficiency varied among the macroalgae density. In general, treatments T2, T3, and T4 showed the best nutrient uptake rates. The maximum uptake rate of ammonium and phosphorus was 6.3 and 3.3 μmol g-1 (dry weight) h-1 meanwhile the maximum reduction efficiency of ammonium and phosphorus was 83.7% and 70.4%, respectively. The main conclusion of this study was that the seaweed G. lemaneiformis is a good candidate for the integration in IMTA systems with scallops, the macroalgae were capable of remove most of the ammonium and phosphorus generated by scallops.

For more details see: Mao et al. (2009) Potential of the seaweed Gracilaria lemaneiformis for integrated multi-trophic aquaculture with scallop Chlamys farreri in North China. Journal of Applied Phycology 21, 649-656.

Biodeposits from Mytilus edulis: a potentially high-quality food source for the polychaete, Hediste diversicolor

Previous studies have demonstrated undoubtedly that the deposit feeding polychaete, Hediste diversicolor, can efficiently handle sludge from land based aquaculture by working detritus into the sediments, thereby, avoiding clumping. In a study by Bergström and his team, the growth and survival rates of H. diversicolor fed on mussel faeces was investigated. Moreover, in order to understand the consequences of experimental handlings, the effects of chemical fluxes in and out of the sediment were also evaluated.

Strong differences in growth were observed between the different treatments, though, no difference was observed in short-term survival. The polychaetes grew on average 17% in wet weight after a period of 10 days when fed only on mussel faeces, as compared to 3% when given equivalent amounts of organic matter from the natural sediments. However, an increase in growth 19–20% growth was observed when polychaetes were administered a mixture of faeces and natural sediments, thus, suggesting an approximate additive effect of the two food sources. Chemical analysis showed that irrespective of the origin, the oxygen consumption increases with the load of organic material; higher fluxes of ammonia was caused by faecal material as compared to natural organic material. However, neither oxygen consumption nor nutrient fluxes were affected by the ashing of sediments. On the contrary, increased fluxes of silicate was observed as a consequence of ashing but were not affected by the addition of mussel faeces. Therefore, regardless of the experimental artefacts owing to ashing of sediments, this study showed that oxygen and nutrient dynamics responded accordingly to the manipulations of organic material and not to the potential alterations of the sediment composition. Hence, the observed effects on the growth of H. diversicolor can be manifested as due to differences in quality and amount of organic material administered. In fact, mussel faeces turned out to be is a high-quality food source for H. diversicolor. Furthermore, with sufficient data from previous studies in connection to bioturbation, the authors conclude H. diversicolor to be a potential candidate in further efforts to develop practical elucidations based on bioturbation for mitigation of adverse effects on benthic environments associated with mussel-farming.

For details please visit: Biodeposits from Mytilus edulis: a potentially high-quality food source for the polychaete, Hediste diversicolor

Integrated Multi-Trophic Aquaculture (IMTA) in Marine Temperate Waters

In this summary the ongoing situation and the potential for the practice of integrated multi-trophic aquaculture (IMTA) in the world’s marine temperate waters are highlighted. As is well known these days, IMTA in fact, is one of the most promising pathways in the evolution of sustainable aquaculture systems. Currently, most research is focused on biomitigation technologies and implemented within various aquaculture systems in order to minimize the impacts of excess nutrients on the surrounding areas. IMTA combines fed aquaculture species (e.g. finfish/shrimps) with organic extractive culture (e.g. suspension feeders/deposit feeders/herbivorous fish) and inorganic extractive species (e.g. seaweeds, halophytes) in such a way that waste produced by the fed culture becomes input for the extractive cultures.IMTA

In fact,

  • The only countries to have IMTA systems near commercial scale, or at commercial scale are: Canada, Chile, China, Ireland, South Africa, the United Kingdom of Great Britain and Northern Ireland (Scotland) and the United States of America.
  • Countries having ongoing research projects related of IMTA are: France, Portugal and Spain.
  • Scandinavian countries, in particular Norway, have made efforts towards the development of IMTA, in spite of possessing a large aquaculture network of finfish.

Aquaculture species in marine temperate waters, possessing particular importance and high potential for development in IMTA systems consist of:

  • Seaweeds such as: Laminaria, Saccharina, Sacchoriza, Undaria, Alaria, Ecklonia, Lessonia, Durvillaea, Macrocystis, Gigartina, Sarcothalia, Chondracanthus, Callophyllis, Gracilaria, Gracilariopsis, Porphyra, Chondrus, Palmaria, Asparagopsis and Ulva.
  • Bivalves: Haliotis, Crassostrea, Pecten, Argopecten, Placopecten, Mytilus, Choromytilus and Tapes.
  • Echinoderms: Strongylocentrotus, Paracentrotus, Psammechinus, Loxechinus, Cucumaria, Holothuria, Stichopus, Parastichopus, Apostichopus and Athyonidium.
  • Polychaetes: Nereis, Arenicola, Glycera and Sabella.
  • Crustaceans: Penaeus and Homarus.
  • Fish: Salmo, Oncorhynchus, Scophthalmus, Dicentrarchus, Gadus, Anoplopoma, Hippoglossus, Melanogrammus, Paralichthys, Pseudopleuronectes and Mugil.

Certain measures and steps wherever appropriate should be taken in order to mitigate the practice of IMTA in these regions.

  • The economic and environmental value of IMTA systems and their co-products should be launched.
  • Selecting the right species, appropriate to the geographical range, accessible technologies, complement each other, efficient and continuous biomitigation, potential market value, and not impose new regulatory impediments to commercialization.
  • Compatibility with a variety of social and political issues.
  • Educating stakeholders about the benefits of IMTA.
  • Creating the R&D&C continuum for IMTA.

Considering all these aspects into account, IMTA can be used as a powerful and valuable tool towards structuring a sustainable aquaculture industry. IMTA systems can be ecologically efficient and environmentally benign.

To know more please visit the link: Barrington K, Chopin T and Robinson S. (2009). Integrated multi-trophic aquaculture (IMTA) in marine temperate waters.

Is Europe ready for integrated multi-trophic aquaculture? A survey on the perspectives of European farmers and scientists with IMTA experience

This study has assessed the current status of European marine-based IMTA and the major impediments to wider IMTA adoption by describing for the first time at such a large spatial coverage, the opinions of farmers and scientists with experience on IMTA.

Thirty-Four people with an average of 74.7 months of experience in IMTA from 12 countries in Europe, answered to a by-phone questionnaire, based on some open-ended questions, structured into three parts: the first part aimed to collect personal information and the location(s) of their IMTA practices; the second part consisted of questions regarding the IMTA application (e.g. the species cultivated, reasons for IMTA application, bottlenecks faced and support received); the third part evaluated the current and future perceptions of farmers/scientists on the IMTA level.

The most used generative species are European sea bass (Dicentrarchus labrax), Gilthead sea bream (Sparus aurata) and Salmo salar. As extractive species, a lot of organisms are used, but only the brown algae (Alaria esculenta and Saccharina latissima), mussels (Mytilus edulis) and scallop (Aequipecten opercularis) are cultured at a commercial level. The major drivers behind the IMTA adoption are the mitigation of nitrogen waste, research of suitable species and enhanced production. EU, national or regional scheme/instrument are used from respondents for the implementation of the IMTA experiments and practices; in particular, respondents from Norway, Denmark and Spain received national financial support on at least one occasion. The major bottlenecks/obstacles faced during IMTA implementation and operation are in the fields of biological (e.g. lack of available seed, lack of knowledge and biofouling that negative interact with culturing processes), environmental, legislative (e.g. financial support from the governments), market (e.g. uncertain profitability) and operational issues such as inadequate technology and lack of infrastructure. Lastly, the largest part of respondents (26%) believe that there is a high potential for IMTA in Europe. However, the most often reported-challenge to overcome for the future development of the IMTA is related to economic and legislation issues, according to the needs of the different regions. 

For more details please visit the link: