A Review of Feeding Mechanism and Nutrient Recycling
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REVIEWS Bivalve Mariculture in Two – Way Interaction with Phytoplankton: A Review of Feeding Mechanism and Nutrient Recycling 1 2 3 Rasheed1Department Olatunji of Fisheries MORUF and*, Gabriel Aquaculture, Femi OKUNADE Bayero University,, Owoyemi Kano, Wahab Kano ELEGBELEYE State, Nigeria 2Department of Biological Sciences, Yaba College of Technology, Lagos State, Nigeria 3Department of Marine Sciences, University of Lagos, Akoka, Lagos State, Nigeria *corresponding author: [email protected] Bulletin UASVM Animal Science and Biotechnologies 77(2)/2020 ISSN-L 1843-5262; Print ISSN 1843-5262; Electronic ISSN 1843-536X DOI:10.15835/buasvmcn-asb: 2020.0010 Abstract Bivalve mariculture is a type of molluscan farming done in open seawater on racks, rafts or longlines where naturally occurring phytoplankton serves as a key food item, introduced into the enclosures with the normal circulation of seawater. Increasingly, the reverse trophic interaction is being recognized; dissolved inorganic and organic waste compounds released by metabolically active bivalves can supply phytoplankton with nutrient and energy requirements for their growth. This two-way interaction can be viewed as a type of community symbiosis developed over long evolutionary timescales. The extent to which this affects overall nutrient budgets and thus primary production is related to the system flushing rate and residence time. Here we reviewed the feeding mechanism and nutrient recycling activities of bivalve and also emphasized the role of phytoplankton as a key nutritional live feed in sustainable bivalve mariculture. Bivalves influence nutrient dynamics through direct excretion and indirectly through microbial mediated remineralisation of their organic deposits in the sediments. The quantitative knowledge of bivalve - phytoplankton trophic interactions in coastal waters will inform bivalve maricultureKeywords: development to effectively, serve the needs of both seafood production and ecosystem restoration. bottom-feeder food web, microalgae, mollusc farming, symbiosis. Introduction in coastal and offshore waters where salinity is Mollusks are important resources that maximal and not subject to significant daily or contribute considerable economic value to the seasonal variation. Mariculture has more recently world’s fisheries. The global production of marine become an important source of bivalve, which is mollusk for human consumption is more than 17 the focus of this review. million tonnes in the year 2018, with China as the Bivalves as a group have noet alhead and they major producer with relatively highest percentage lack some usual molluscan organs like the radula of production (FAO, 2020). In terms of mariculture and the odontophore (Romano ., 2014). They (disregarding freshwater production), mollusc include the clams, oysters, cockles, mussels, production exceeds finfish production value by scallops, and numerous other families that live underover 900-fold controlled (Mau or & semi Jha, 2018).controlled As acondition concept, in saltwater, as well as a number of families that mariculture is the rearing of aquatic organisms live in freshwater. Bivalve mariculture is a type of molluscan farming done in open seawater 2 and al. MORUF on racks, rafts or longlines. The commercial fast rate of primary production (Gao & Campbell, importance of bivalve mariculture include but 2014). Phytoplankton are the autotrophic (self- not limited to food security, pearl production feeding) components of the plankton community Crassostreaand lime manufacture. madrasensis, As C. gryphoides,listed by Narasimham C. rivularis and a key part of oceans, seas and freshwater ba- and(2005), Saccostrea popular cucullata culture species of oysters include sin ecosystems. According to Pal and Choudhury are Perna viridis and P. indica (2014), phytoplankton are free-floating photo- clams are Villorita cyprinoids,; culture Paphia species malabarica, of mussel synthetic aquatic microorganisms, which move Meritrix casta and Anadara; culture granosa species of from one place to another, either actively by their Chlamys barrei, C. locomotor organs (flagella) or passively by water nobills, Placopecten magellanicus and Argopecten while currents. Today, the contribution of phytoplankton irradians.culture species of scallops are to the biosphere continues to be unique because this group largely contributes to the renewal of the atmospheric oxygen and acts as a tremendous 2 One of the factors that influence bivalve etsink al for CO , which is used for the synthesis of or- growth in both natural populations and maricul- ganic compounds through photosynthesis (Nelson ture conditions is availability and quality of food. ., 1995). While accounting for less than 1% of Traditionally, phytoplankton was considered as Earth’s biomass, et al. phytoplankton is responsible for primary food source for bivalves (Gosling, 2003). more than 50% annual net biomass production However, a number of studies pointed out that en- (Bowler , 2010). ergy is also derived from other food sources such Phytoplankton differentiate from other plan- as bacteria, detritus and even zooplankton (Le- ktonic taxa by the presence of photosynthetic hane & Davenport, 2006). Through filter feeding, mem branes. This makes them produce biomass bivalves play important role in marine ecosystems by autotrophically converting naturally occurring by controlling abundances of primary producers, carbon into protoplasm. In this way, phytoplankton zooplankton and larval stages of other marine function as the foundation of the marine food web species. By this process, bivalves haveet al. great influ- by supporting all other life in the ocean. Food webs ence in energy and nutrient flux between benthic are built from food chains. All forms of life in the and pelagic communities (Arapov , 2010). sea have the potential to become food for another The two-way interaction between bivalve life form. In the ocean, a food chain typically starts mariculture and phytoplankton fundamentally with energy from the sun powering phytoplankton, involve feeding and nutrient recycling activities and follows a course shown in Figure 1. of bivalve molluscs, which tend to sustain primary Phytoplankton community supports the base production locally. This paper aimed to give an of the natural food chain depending on which overview of current understanding on bivalve’s the natural fauna including the fish populations feeding mechanism and to emphasize the role can survive (Napiórkowska-Krzebietke, 2017). A of phytoplankton as a key nutritional live feed in simplified classical food web in an aquatic ecosys- bivalve mariculture, by reviewing the worldwide tem comprises phytoplankton as staple food for literature through Internet search engines, zooplankton, and further zooplankton as food textbooks and theses. Literatures obtained were for planktivorous fish, which in turn are food analyzedPhytoplankton in pros and as arelevant Basic Element cited figure in a and for predatory fish. A 2017 study estimated the headingsClassical were Food adopted. Web nutritional value of natural phytoplankton in terms of carbohydrate, protein and lipid across the world ocean using ocean-colour data from satellites, and Unlike terrestrial environments, marine en- found the calorific value of phytoplankton to vary vironments have biomass pyramids which are considerablyBiologically across Active different Ingredients oceanic of regions and inverted at the base. In particular, the biomasset al. of betweenPhytoplankton different times of the year (Roy, 2018). consumers (copepods, krill, bivalve) is larger than the biomass of primary producers (Arapov , 2010). This happens because the ocean’s primary Phytoplankton produce valuable compounds producers are tiny phytoplankton, which grow that include crucial phytonutrients and biological- Bulletinand reproduce UASVM Animal Sciencerapidly, and Biotechnologiesso a small 77(2)mass / 2020 can have a ly active ingredients, e.g. fatty acids, amino acids, 3 Bivalve Mariculture in Two – Way Interaction with Phytoplankton: A Review of Feeding Mechanism and Nutrient Recycling Figure 1. Summary of phytoplankton as a basic element in a classical food web Figure 2. Notable biomolecules from phytoplankton biomass carotenoids, chlorophyll, vitamins, antioxidants 2013). These bio-compounds play physiological (Figure 2). Thus, thorough nutritional and toxico- roles that allow cells to deal with changes of the logical investigations have validated the suitabilet al.- environmental constrains. For example, the diver- ity of algal biomass for use as a high-grade feed in sity of light-harvesting pigments allows efficient the production of bivalve molluscs (Kovač , Bulletin UASVM Animal Science and Biotechnologies 77 (2) / 2020 4 and al. MORUF et al. photosynthesis at different depths in the seawater pendent on both the energy status and the taxo- column (Heydarizadeh , 2013). nomic composition of the phytoplankton commu- Regarding lipids in aquatic ecosystems, phy- nity, with some microalgal classes being devoid of toplankton can predominantly synthesize poly- these compounds (e.g., chlorophytes have no PU- unsaturated fatty acids (PUFA), which in turn are etFAs al. longer than 18 carbons, but 20 - and 22 - car- mainly consumed by zooplankton and benthic bon FeedingPUFAs are Mechanism considered of to Bivalve be essential) (Kovač invertebrates. Different groups of phytoplankton , 2013). such as cryptophytes, diatoms, dinophytes and euglenophytes, can synthesize high amounts