Impact of fouling organisms on mussel rope culture: interspecific competition for food among suspension-feeding invertebrates (original) (raw)
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Marine Ecology, 2009
The importance of suspension-feeding mussels is particularly apparent in benthic communities; however, the role of this feeding strategy on the development of macroalgal and associated invertebrate communities is in general poorly known. The effect of suspension-feeding mussels Mytilus trossulus on benthic communities was studied in an in situ factorial field experiment in the Northern Baltic Sea over one ice-free season. The experiment was performed under different regimes of wave exposure (low and moderate) and on different sedimentary habitats (soft bottom with high organic content, soft bottom with low organic content, and hard bottom). In general the presence of mussels was associated with increased biomass of filamentous algae, herbivores and deposit feeders and decreased biomass of charophytes. The effect of M. trossulus interacted with the effect of exposure and substrate. Stronger responses were observed in moderately exposed than in sheltered areas. The presence of M. trossulus affected charophytes and deposit feeders on sand with low content of organic matter and filamentous algae on pebbles but not on other substrate types. The magnitude of the effects varied between months. The results suggest that (i) even in dynamic coastal systems the biodeposits and excretions of mussels are at least partly assimilated locally and are not flushed away to the open sea, (ii) the accumulation of faecal material induced elevated growth of deposit feeders, (iii) mussels enhanced the growth of ephemeral macroalgae and reduced the growth of perennial macroalgae, and (iv) together with increasing benthic primary production, mussels indirectly increase the production of herbivores.
Marine Ecology, 2009
Suspension-feeding mussels link water column productivity to the benthos by removing pelagic organisms, increasing rates of particle deposition and promoting nutrient recycling (Cloern 1982; Kotta & Møhlenberg 2002; Lauringson et al. 2007). Part of the deposited faeces and pseudofaeces are consumed by deposit feeders (Zhou et al. 2006) and the remaining part decomposes, thereby increasing the availability of inorganic nutrients that may be channelled into benthic and pelagic production (Reusch et al. 1994; Marinelli & Williams 2003; Giles & Pilditch 2006). Besides notable biodeposition, bivalves excrete ammonia and thus may directly influence nutrient levels in seawater (Dame et al. 1991; Bracken 2004; Bracken & Nielsen 2004). Despite the importance of studies quantifying the effects of suspension feeders on macroalgal and associated invertebrate communities, such studies are
Aquatic Invasions, 2009
This study was undertaken to quantify the ecological interactions between blue mussels (Mytilus edulis Linnaeus 1758) and vase tunicates (Ciona intestinalis Linnaeus 1767) in the context of mussel farming. To quantify the extent of competition for food resources at varying temperatures, clearance rates for both species were calculated using Tetraselmis striata (Butcher 1959). Between 4-13°C, mussel clearance rates were at least three times higher than those of tunicates. At 16°C and 19°C, the mussel clearance rates fell to the same level as the tunicates. Clearance rates were also examined using different sized algal species, and a substantial overlap in mussel and tunicate particle size utilization was observed. To determine the effects of tunicate density on mussel productivity, size and condition indices were measured in the field under varying tunicate density. Mussel size and condition decreased with increasing tunicate densities. In addition, up to 50% mussel mortality was observed under heavy tunicate fouling (~2 kg•m-1). Mussels and tunicates have the potential for substantial food resource competition, and tunicates were found to have a negative effect on mussel productivity. Heavy tunicate fouling was associated with higher mussel mortality, lower overall size and condition. The cost effectiveness of removing the vase tunicate from mussel lines is also discussed.
Journal of Experimental Marine Biology and Ecology, 2008
The Grande-Entrée Lagoon (Magdalen Islands, Canada) has supported mussel (Mytilus edulis) cultivation for the last 25 years. Algal biomass in this lagoon is relatively low while heterotrophic plankton biomass is high. Although often considered herbivorous, it is known that filter-feeding bivalves can consume various types of food, from bacteria to zooplankton. We hypothesize that along with phytoplankton, heterotrophs constitute an important food resource for the Grande-Entrée mussels. In situ mesocosm experiments were undertaken at different seasons using short socks filled with mussels from the same cohort taken from an aquaculture farm, in order to determine the impact of cultured mussels on local plankton communities and assess the role of heterotrophs. Filtration activity by the mussels and associated epibionts present in the socks was expressed as clearance rates (CR). The average CR over all taxa was lowest in June and highest in October. Diatoms, dinoflagellates and heterotrophic protists constituted the bulk of planktonic carbon removed by mussels. While smaller-sized taxa contributed little (b 5%) to mussel carbon intake, large-sized heterotrophs (namely ciliates) contributed 69 to 88%. Taxon-marker pigment analyses generally confirmed these observations for groups containing phototrophic pigments. The high heterotrophic biomass retained by mussels indicates they are a major food source for mussels in this environment and should be considered both in the evaluation of mussel feeding and in assessing the influence of cultured mussels on local plankton ecosystems.
https://www.academia.edu/2922734/ ; Inhibition of mussel suspension feeding by surfactants of three classes
Inhibition of mussel suspension feeding by surfactants of three classes. S. A. Ostroumov1,* & J. Widdows2; 1Laboratory of Physico-Chemistry of Biomembranes, Faculty of Biology, Lomonosov Moscow State University, Lengory, Moscow 119991, Russian Federation; 2Plymouth Marine Laboratory, Prospect Place, West Hoe, PL1 3DH, Plymouth, England; (*Author for correspondence: E-mail: ar55[at]yandex.ru ) Keywords: surfactants, filter-feeders, clearance rates, marine mussels, toxicity; Abstract: Effects of three surfactants on the filtration rates by marine mussels were studied. The xenobiotics testedrepresented anionic, cationic and non-ionic surfactants (tetradecyltrimethylammonium bromide, a repre-sentative of a class of cationic surfactants; sodium dodecyl sulphate, a representative of anionic alkyl sulfates;and Triton X-100, a representative of non-ionic hydroxyethylated alkyl phenols). All three surfactantsinhibited the clearance rates. The significance of the results for the ecology of marine ecosystems is discussed. Abbreviations: CR – clearance rate; EMIS – the electromagnetic induction system; SDS – sodium dodecylsulphate; TDTMA – tetradecyltrimethylammonium bromide; TX100 – Triton X-100; Introduction. Suspension feeders (filter-feeders) play a significantfunctional role in aquatic ecosystems. The impor-tant role of filter-feeders (particularly molluscs) isdue to their high rates and volumes of water fil-tration (Walz, 1978; Alimov, 1981; Jørgensenet al., 1986; Kryger & Riisga ̊rd, 1988; Shulman &Finenko, 1990; Zaika et al., 1990; Dame, 1996). Asa result of biological filtration, suspended particlesand cells of phytoplankton and microbial plank-ton are removed from the water. This process alsoaccelerates mineralization of organic substances inthe filtered matter. Therefore, biological filtrationcontributes significantly to water purification inaquatic ecosystems.Filter-feeders can accelerate carbon fluxes inecosystems, because the production of biodeposits(faecal and pseudofaecal pellets) leads to enhancedrates of sedimentation. As a result, bivalves wereshown to influence material flux at the sediment–water interface (Smaal et al., 1986; Kautsky &Evans, 1987; Jaramillo et al., 1992; Dame, 1996;Widdows et al., 1998).Biodeposition rates were estimated as high as60 gm)2h)1at a density of 1400 mussels m)2(i.e.,50% surface cover) in a mussel (Mytilus edulis)bed at Cleethorpes (Humber estuary, England)(Widdows et al., 1998), which is higher thanmaximum recorded biodeposition rates of25 gm)2h)1forM. edulisin the Oosterschelde inthe Netherlands (Smaal et al., 1986) and18 gm)2h)1forM. chilensisin an estuary in Chile(Jaramillo et al., 1992). Biodeposition rates insome ecosystems were up to 40 times the naturalsedimentation rates. Kautsky & Evans (1987)estimated annual biodeposition per g mussel (M.edulis, dry weight including shells) as high as1.76 g dry weight, 0.33 g ash-free dry weight,0.13 g carbon, 1.710)3g nitrogen and2.610)4g phosphorus. The annual biodepositionis 11.7 g dry weight per g mussel shell-free dryweight. When average mussel biomass was620 gm)2(dry weight including shells) or 91 gm)2(dry flesh weight), the annual biodeposition per m2was 1092 g (dry weight), including 80.7 g C, 10.4 gN, 1.6 g P (Kautsky & Evans, 1987). The averagecomposition during the year, expressed as percent... (see the text) [Hydrobiologia (2006) 556:381–386]; https://www.academia.edu/2922734/ ;
Helgoland Marine Research, 2015
Filtration capacity and feeding behaviour has been intensely studied for adult mussels (Mytilus edulis), but less information is available for juvenile mussels (1.5-25 mm, \1 year), especially in natural sea water. The recent introduction of mussel seed collectors in the Netherlands prompted the need for more detailed information on juvenile mussel behaviour. To estimate the impact of juvenile populations on ecosystem carrying capacity, information on clearance rate as well as usage of different prey items is essential. Clearance rates were measured in an experimental study, incubating juvenile mussels in natural sea water. Rates were related to isometrics as well as specified for the prey items bacteria, picophytoplankton (\3 lm), nanophytoplankton (3-20 lm), and ciliates. Results showed that the clearance rate of juvenile mussels depends on shell length 2 , while the relationship between clearance rate and weight was more variable. Length is thus a better parameter for estimating clearance rate than weight. Ciliates and nanophytoplankton were cleared at comparable, but variable rates, while picoalgae were cleared from the water at the rate of 11-64 % compared to nanophytoplankton. For bacteria, the clearance rate was on average 9 %. This study showed different retention of particles of similar size (picoalgae and bacteria) as well as variability in particle retention for the different prey items. This variable retention efficiency could not be related to seston concentration nor to dominance in cell size. The results from this study can be used to estimate the effect of mussel seed collectors on the carrying capacity of the Dutch Wadden Sea.
Journal of Marine Biology, 2011
Under optimal conditions, bivalves tend to filter the ambient water at a maximum rate but under suboptimal environmental conditions, including low or very high algal concentrations, the filtration rate is reduced. The upper algal concentration at which the blue mussel, Mytilus edulis, exploits its filtration capacity over an extended period of time was identified by stepwise raising the algal (Rhodomonas salina) concentration in steady-state experiments above the threshold for continuous high filtration rate. The duration time before incipient saturation reduction decreased with increasing algal concentration, and the threshold concentration for incipient saturation reduction of filtration activity was found to be between about 5,000 and 8,000 cells mL −1 , equivalent to 6.3 and 10.0 µg chl a L −1 , respectively. Reduced filtration rate was related to total number of algal cells ingested previous to incipient saturation and found to be 11.4 ± 1.7 × 10 6 cells. Video-microscope recordings of pseudofaeces production revealed that the trigger threshold concentration for formation of pseudofaeces was about 12,000 cells mL −1. Faeces produced by saturated mussels consisted of closely packed undigested algal cells, indicating severe overloading of the digestive system caused by high algal concentrations which mussels are not evolutionary adapted to cope with.
Filtration rate of blue mussels as a function of flow velocity: preliminary experiments
Journal of Experimental Marine Biology and Ecology, 1990
The filtration rate of adult blue mussel Mytilus edulir L. was measured in flume flows ranging from 6-38 cm. s-' at a constant seston concentration. At > 25 cm. s-', blue mussel filtration rates were low, < 10% of 10" cells. ml-I of Chroomonas salina filtered. h-' vs. up to 41 y0 at 6.8 cm. s-'. The mechanism of flow-induced inhibition of filtration rate in the blue mussel could not be determined by the experimental approach used. Two previously described mussel pump characteristics initiated in response to increases in ambient flow pressure-pump shutdown or gill bypass shunting-are possible explanations for feeding inhibition.
Freshwater Biology, 2009
1. We investigated the role of algal composition on pumping, clearance, assimilation, pseudofaeces and faeces production, feeding time budgets, and condition of zebra mussels from spring to autumn at two sites in Saginaw Bay (Lake Huron) and one site in western Lake Erie. Size-fractioned chlorophyll was used to distinguish between feeding on small (<53 lm) and large (>53 lm) size fractions, and mussel feeding behaviour was quantified by video observations. 2. Mussel pumping, clearance and assimilation rates varied among sites, particularly during summer, when phytoplankton composition varied considerably among sites. Lowest values were seen at the inner-bay site of Saginaw Bay, low to moderate values at the outer-bay site of Saginaw Bay, and high values at the Lake Erie site. Clearance, pumping and assimilation rates were all highly positively correlated (R 2 = 0.76) with per cent contribution of flagellates to total algal biomass and negatively correlated with per cent of Microcystis aeruginosa (R 2 = 0.63). The negative effects on pumping rate (as determined by clearance rate on the <53 lm fraction) of Microcystis, which occurred in the >53 lm fraction, could be mitigated by the presence of flagellates in the <53 lm fraction. 3. Visual observations of mussel feeding showed evidence for poor seston quality during summer negatively affecting feeding rates. High faeces production during times of low assimilation rate was suggestive of poor assimilation efficiency and ⁄ or viable gut passage of grazing resistant algae. Long periods of time not filtering by the mussels during some Microcystis blooms and lack of production of a filtering current during one experiment were suggestive of intoxication from microcystin or other secondary compounds. 4. Clearance and feeding rates of the mussels in Saginaw Bay were high during spring and autumn and very low in summer, particularly at the inner-bay site. Condition of the mussels (mass : length ratio) was highest in spring and lowest during summer. This seasonal variation probably reflected high food assimilation rate during autumn and spring and low assimilation rate and reproduction during summer. The condition of mussels throughout the year was higher at the outer-bay than the inner-bay site, reflecting better feeding conditions at the former. Mussel selective feeding may have been responsible for the poor quality of food at the inner bay site; therefore, we postulate that a regime shift in phytoplankton composition promoted by the mussels fed back into lowered condition of the mussels.