Saccostrea Research Articles

Analysis of the α-amylase gene sequence and the enzyme activity of Indian rock oyster Saccostrea forskali

Indian rock oyster Saccostrea forskali is an important commercial species in Thailand. In this study, its full-length α-amylase (SfAmy) cDNA nucleotide sequence was investigated. The SfAmy cDNA was 1,689 bp long and contained a 1,563-bp open reading frame encoding 520 amino acid residues, including a 17-amino acid signal peptide. The molecular mass and the estimated isoelectric point (pI) of the deduced mature S. forskali α-amylase (SfAMY) were 55.948 kDa and 6.45, respectively. The deduced protein sequence showed 45–88 % identity to other mollusk AMYs. The molecular weight was confirmed by the weight of the purified native enzyme. The specific activities of crude and purified native enzymes toward 1 % starch were 29.53 and 187.42 U/mg. In addition, the obtained recombinant SfAMY also showed activity in digesting 1 % starch. The specific activities of the crude and purified recombinant proteins were 11.8 and 46 U/mg. Both enzymes showed optimal activity temperature at 40 °C but their optimum pH values were different, 6.0 for the native and 5.0 for the recombinant. The expression of SfAmy examined by RT-PCR showed the highest levels in the digestive gland but none was observed in the adductor muscle.

A new Imogine species (Turbellaria: Polycladida: Stylochidae) associated with rock oysters (Saccostrea cucullata) from the Persian Gulf, with a review of the genus.

A new species of acotylean polyclad, Imogine qeshmensis sp. nov. is described from Qeshm Island, Persian Gulf, Iran. I. qeshmensis is characterized by the number and arrangement of the tentacular, cerebral and frontal eyes, a body margin with opaque white bands and eyespots and a male genital complex with an highly muscular seminal vesicle equal in size to the prostatic vesicle.

A Novel Paramyxean Parasite, Marteilia granula sp. nov. (Cercozoa), from the Digestive Gland of Manila Clam Ruditapes philippinarum in Japan

The genus Marteilia includes protozoan species with repeated endogenous budding sporulation and spores that corise three cells.mp All of these species are parasitic for marine invertebrates. Most species in this genus are observed in the digestive tissue of bivalves. One of the st important species, mo Marteilia refringens, has been observed in the European flat oys-ter, Ostrea edulis (Grizel et al., 1974); mussels, Mytilus edulis and Mytilus galloprovincialis (Tige and Rabouin, 1976; Villalba et al., 1993); razor clam, Solen margina-tus and the striped venus cla Chamalea gallinam,(Lopes-Flores et al., 2008a, 2008b) in Europe. Because of the econoc impact of M. refringensmi on the flat oyster industry, this species is listed as a notifiable pathogen by World Organization for Animal Health (OIE, 2012). Another species, Marteilia sydneyi, hasdetrimental impacts on the Sydney rock oyster, Saccos-trea glomerata, in Australia (Perkins and Wolf, 1976; Green et al., 2011). The recently identified species Marteilia cochillia was involved in rtality of the edible mocockle, Cerastoderma edule, in Spain (Carrasco et al., 2013). Although relatively less information is available, M. lengehi (Comps, 1976) and M. christenseni (Comps, 1985) have also been observed in Saccostrea cucullata and Scrobicularia piperata In Asian , respectively.

Occurrences of the Indo-West Pacific rock oyster Saccostrea cucullata in mainland Japan

We surveyed 110 Saccostrea oysters sampled from southern Kagoshima Bay and Wakayama Prefecture to monitor the species diversity of marine benthos using morphological features and DNA barcoding. Prior to the survey, we re-identified 55 Saccostrea oysters sampled from the Yaeyama Islands, a hot spot for Saccostrea species in Japan. Analysis of partial nucleotide sequences from the mitochondrial large subunit of ribosomal DNA (LSrDNA) led to the discovery of the Indo-West Pacific rock oyster S. cucullata-F in Kagoshima Bay, and S. cucullata-C and S. cucullata-F in Wakayama Prefecture. This is the first record of the Indo-West Pacific rock oyster in mainland Japan (Hokkaido, Honshu, Shikoku and Kyushu Islands). We postulate that there may have been a northward shift in the distribution patterns of the species due to global warming, these Pacific rock oysters are relic species from the Middle or Late Pleistocene, or the non-indigenous species were introduced by oil tanker or other industrial activities.

The density and spatial arrangement of the invasive oyster Crassostrea gigas determines its impact on settlement of native oyster larvae

Understanding how the density and spatial arrangement of invaders is critical to developing management strategies of pest species. The Pacific oyster, Crassostrea gigas, has been translocated around the world for aquaculture and in many instances has established wild populations. Relative to other species of bivalve, it displays rapid suspension feeding, which may cause mortality of pelagic invertebrate larvae. We compared the effect on settlement of Sydney rock oyster, Saccostrea glomerata, larvae of manipulating the spatial arrangement and density of native S. glomerata, and non-native C. gigas. We hypothesized that while manipulations of dead oysters would reveal the same positive relationship between attachment surface area and S. glomerata settlement between the two species, manipulations of live oysters would reveal differing density-dependent effects between the native and non-native oyster. In the field, whether oysters were live or dead, more larvae settled on C. gigas than S. glomerata when substrate was arranged in monospecific clumps. When, however, the two species were interspersed, there were no differences in larval settlement between them. By contrast, in aquaria simulating a higher effective oyster density, more larvae settled on live S. glomerata than C. gigas. When C. gigas was prevented from suspension feeding, settlement of larvae on C. gigas was enhanced. By contrast, settlement was similar between the two species when dead. While the presently low densities of the invasive oyster C. gigas may enhance S. glomerata larval settlement in east Australian estuaries, future increases in densities could produce negative impacts on native oyster settlement. Synthesis and applications: Our study has shown that both the spatial arrangement and density of invaders can influence their impact. Hence, management strategies aimed at preventing invasive populations reaching damaging sizes should not only consider the threshold density at which impacts exceed some acceptable limit, but also how patch formation modifies this.

Broodstock Conditioning, Spawning Induction, and Early Larval Development of the Tropical Rock OysterStriostrea prismatica(Gray 1825)

The tropical rock oyster Striostrea prismatica is a commercially valuable bivalve mollusc found along the Pacific tropical coast. A laboratory study was conducted to investigate broodstock acclimation at two temperatures (28.3 ± 0.9°C and 22.2 ± 0.9°C) fed a combined microalgae diet (Chaetoceros gracilis and Isochrysis galbana at 150 cells/µL/day and 100 cells/µL/ day, respectively) for 7 wk, and to investigate seven treatments to stimulate spawning of individuals acclimated at both temperatures. Treatments to induce spawning consisted of a 10°C temperature decrease for 60 min (HS1), a temperature increase to 30°C for 30 min (HS2), a 5°C temperature increase for 60 min followed by 30 min of desiccation (HSD), a decrease in salinity to 15 psu for 30 min (SS1), an increase in salinity to 96 psu for 30 min (SS2), overfeeding with C. gracilis microalgae (OF), and the addition of oyster sperm (SPM). All treatments were treated with oyster sperm after 1 h of the last stimulus. Spawning success was evaluated by measuring egg production, fertilization percentage, and response time of spawning. Only broodstock held at 28°C spawned (51.8%). All organisms in the HSD treatment spawned after 1.40 ± 1.01 h. Oocytes released per individual and fertilization rate averaged 34.88 ± 23.81×106 and 89.82 ± 5.90%, respectively. Addition of sperm enhanced spawning success in the HS1, HS2, and SS1 treatments.

Assessment of Qx and Winter Mortality Disease Resistance of Mass Selected Sydney Rock Oysters, Saccostrea glomerata (Gould, 1850), in the Hawkesbury River and Merimbula Lake, NSW Australia

The Sydney rock oyster, Saccostrea glomerata, mass selection breeding program was established in 1990 in the Georges River, New South Wales, and has successfully developed lines of oysters resistant to QX disease (Marteilia sydneyi) and winter mortality disease (WM; Bonamia roughleyi). Each new generation is assessed in the Georges River, but the performance of these oysters in other estuaries affected by these diseases is unknown. To investigate the potential for genotype and environment interactions, and to assure farmers, survival and growth of progeny of the fourth-generation breeding lines developed in Georges River were assessed in two other key farming areas; the Hawkesbury River and Merimbula Lake, NSW, Australia. Hawkesbury River is affected by QX and was used to assess the QX-resistant oysters (QXr). Merimbula Lake is affected by WM, and this estuary was used to assess the WM-resistant oysters (WMr) and the dual WM and QX resistant line (WM QXr). Oysters that are QXr in the Hawkesbury River, and the WMr oysters in Merimbula Lake, had significantly lower mortality and faster growth compared with controls at the final measurement. Oysters that are QXr in the Hawkesbury River at the Marra Marra Creek and Kimmerikong Bay sites attained the 50-g "plate grade" benchmark after 24 mo of culture and had lost only 29.4% and 16.9% of oysters originally stocked, respectively. Meanwhile, QX caused losses of 93.7% and 95.7% in controls at these 2 sites, respectively. In Merimbula Lake, at the conclusion of the experiment WMr oysters were significantly heavier, were larger, and had significantly lower mortality than WM QXr and control oysters. Growth and survival of WMr, WM QXr, and QXr oysters were comparable with that measured in the Georges River.

Hemiuroid trematode sporocysts are undetected by hemocytes of their intermediate host, the ark cockle Anadara trapezia: Potential role of surface carbohydrates in successful parasitism

In order to establish a successful relationship with their hosts, parasites must subvert or evade immune defences. Cockle Anadara trapezia and Sydney Rock oyster (SRO) Saccostrea glomerata live in the same location but only ark cockles are infected by sporocysts of hemiuroid trematode. This provides an opportunity to explore differing interactions between the parasite and the immune system of susceptible and refractive hosts. Rapid migration and encapsulation of sporocysts was observed by SRO hemocytes but not by cockle hemocytes. This migration/encapsulation was inhibited by N-acetylglucosamine or N-acetylgalactosamine but not by the other sugars, implicating specific surface carbohydrates in immune detection. Effector responses of hemocytes were investigated in vitro in terms of production of reactive oxygen production (ROS). Hemocytes of both species strongly reacted to Zymosan, but only SRO hemocytes responded to live sporocysts. Neither species' hemocytes produced ROS in the presence of dead/fixed sporocysts, and there was no suppression of Zymosan-induced respiratory burst by sporocysts. This suggests that immune escape is mediated by avoiding encapsulation, perhaps through molecular mimicry. Membrane-shaving with proteases indicated that sporocyst surface proteins are not a key factors in hemocytic detection. Surface carbohydrates of SRO and cockle hemocytes and of sporocysts were profiled with a panel of biotinylated lectins. This revealed substantial differences between cockle and SRO hemocytes, but greater similarity between cockle hemocytes and sporocysts. Results suggest that surface carbohydrates play an integral role in hemocyte immunorecognition and that surface carbohydrate molecular mimicry is a potential strategy for immune evasion in cockles by hemiuroid trematode sporocysts.

A microbial spoilage profile of half shell Pacific oysters (Crassostrea gigas) and Sydney rock oysters (Saccostrea glomerata)

This study aimed to assess bacterial spoilage of half shell Pacific and Sydney rock oysters during storage using microbial culture and 16S rRNA pyrosequencing. Odour and pH of oyster meats were also investigated. Estimation of microbiological counts by microbial culture highlighted growth of psychrotrophic bacteria. During storage, odour scores (a score describing deterioration of fresh odours where a score of 1 is fresh and 4 is completely spoiled) increased from 1.0 to 3.0 for Pacific oysters and from 1.3 to 3.4 for Sydney rock oysters. pH results obtained for both species fluctuated during storage (range 6.28–6.73) with an overall increase at end of storage. Pyrosequencing revealed that the majority of bacteria at Day 0 represented taxa from amongst the Proteobacteria, Tenericutes and Spirochaetes that have not been cultured and systematically described. During storage, Proteobacteria became abundant with Pseudoalteromonas and Vibrio found to be dominant in both oyster species at Day 7. Analysis of the pyrosequencing data showed significant differences in bacterial profiles between oyster species and storage time (both P = 0.001). As oysters spoiled, bacterial profiles between oyster species became more similar indicating a common spoilage profile. Data presented here provides detailed insight into the changing bacterial profile of shucked oysters during storage and has identified two genera, Pseudoalteromonas and Vibrio, as being important in spoilage of shucked oysters.

A Remarkable Recovery in the Sydney Rock Oyster (Saccostrea glomerata) Population in a Highly Urbanised Estuary (Sydney Estuary, Australia)

Birch, G.F.; Apostolatos, C., and Taylor, S.E., 2013. A Remarkable Recovery in the Sydney Rock Oyster (Saccostrea glomerata) Population in a Highly Urbanised Estuary (Sydney Estuary, Australia).Surveys of the Sydney rock oyster (Saccostrea glomerata) in the Sydney estuary (Australia) in 1995 and 2005 provided evidence of a significant and widespread increase in the abundance of this bivalve over this period. Oyster abundance and density increased predominately in the upper estuary where a 300% increase in water-line length coverage occurred over the 10-year period. The timing of increased abundance and co-incidence of high-shipping activity with areas of maximum oyster increase, suggest that partial banning of tributyltin in 1989 may have played a major role in the increase of S. glomerata in this estuary.

The recovery of oyster (Saccostrea glomerata) populations in Sydney estuary (Australia)

The current work documented a significant and widespread increase in the abundance of the Sydney rock oyster Saccostrea glomerata, in Sydney estuary (Australia) by undertaking surveys of oyster density in the estuary in 1989 and annually from 1994 to 2006. Oyster density at six control sites located in nearby National Parks unaffected by boating and stormwater discharges were compared to 17 study sites widely distributed within Sydney estuary. No oyster populations were evident in Sydney estuary in 1989; however, by 1994 oysters had colonised areas of the lower and central estuary and by 2002 densities were statistically similar to control sites. The timing of estuary-wide increases in oyster abundance suggests that the partial banning of tributyltin in 1989 for vessels under 25m long may have played a major role in the increase of S. glomerata in this estuary.

The Onset and Termination of the Qx Disease Window of Infection in Sydney Rock Oyster (Saccostrea glomerata) Cultivated in the Hawkesbury River, NSW, Australia

Since the 1970s, significant QX disease outbreaks have taken place in Sydney rock oyster (Saccostrea glomerata)producing estuaries in New South Wales, Australia, devastating production. Despite research efforts, there are still many gaps in our knowledge of QX disease (causative agent: Marteilia sydneyi). A better understanding of the timing and triggers of the QX infection would allow the management of oyster farms to be tailored to address the high-risk period. This study examined the extent and variability of the QX window of infection across multiple years (2005/2006 to 2008/2009) in the Hawkesbury River and characterized environmental conditions prior to, during, and after the infection window during these years. The window of QX infection onset across the years was found to be highly variable, with start times occurring between November and February, whereas the infection termination time was more defined, occurring within the first week in April, except in 2006/2007, which ceased during the last week of April. The termination of the infection window occurred during a significant decrease in water temperature (at a rate of 3.7°C/mo), with no infection occurring at water temperatures less than 21.5°C Environmental conditions were more variable at the onset of the infection window, when water temperatures showed high levels of variability among years as a result of cool freshwater inputs from rainfall events, which occur commonly at this time of year. These freshwater inputs also resulted in significant decreases in salinity levels (to at least ∼10 ppt), which may be an additional factor influencing QX disease outbreaks. Previous QX work suggested an infection period of 19 days; here, longer infection periods were observed and lasted between 8 wk and 18 wk, depending on the year.

Identification and characterisation of an ostreid herpesvirus-1 microvariant (OsHV-1 µ-var) in Crassostrea gigas (Pacific oysters) in Australia

Between November 2010 and January 2011, triploid Crassostrea gigas (Pacific oysters) cultivated in the Georges River, New South Wales, experienced >95% mortality. Mortalities also occurred in wild diploid C. gigas in the Georges River and shortly thereafter in the adjacent Parramatta River estuary upstream from Sydney Harbour. Neighbouring Saccostrea glomerata (Sydney rock oysters) did not experience mortalities in either estuary. Surviving oysters were collected to investigate the cause of mortalities. Histologically all oysters displayed significant pathology, and molecular testing revealed a high prevalence of ostreid herpesvirus-1 (OsHV-1). Quantitative PCR indicated that many C. gigas were carrying a high viral load at the time of sampling, while the load in S. glomerata was significantly lower (p < 0.001). Subsequent in situ hybridisation experiments confirmed the presence of a herpesvirus in C. gigas but not S. glomerata tissues, suggesting that S. glomerata is not susceptible to infection with OsHV-1. Naïve sentinel triploid C. gigas placed in the Georges River estuary in January 2011 quickly became infected and experienced nearly 100% mortality within 2 wk of exposure, indicating the persistence of the virus in the environment. Phylogenetic analysis of sequences derived from the C2/C6 region of the virus revealed that the Australian strain of OsHV-1 belongs to the microvariant (µ-var) cluster, which has been associated with severe mortalities in C. gigas in other countries since 2008. Environmental data revealed that the Woolooware Bay outbreaks occurred during a time of considerable environmental disturbance, with increased water temperatures, heavy rainfall, a toxic phytoplankton bloom and the presence of a pathogenic Vibrio sp. all potentially contributing to oyster stress. This is the first confirmed report of OsHV-1 µ-var related C. gigas mortalities in Australia.

Blooms of Pyrodinium bahamense var. compressum and rock oyster toxicity in Costa Chica, Guerrero, Mexico

Blooms of Pyrodinium bahamense var. compressum were detected from July to December 2010 in Costa Chica, Guerrero. To estimate the cell abundance of this dinoflagellate, phytoplankton samples were collected from 7 July to 9 December 2010 at five sampling sites. Wild rock oysters and specimens from fishing cooperatives were only collected during November-December 2010. Abundance of P. bahamense var. compressum ranged from &lt; 1000 to 194000 cells L–1 in the first three samplings performed in July. Low densities (&lt; 9000 cells L–1) were observed at the end of November and December. Rock oyster toxicity from the fishing areas ranged from 46.24 to 788.85 μg STXeq 100 g–1. Rock oyster samples collected in the fishing cooperatives had toxicity from 52.2 to 440.88 μg STXeq 100 g–1. Although rock oysters were collected at the end of the blooms, their toxicity could be associated to this dinoflagellate both during this period and during previous blooms thatoccurred from on July-August in the study area.

Bioaccumulation of Cd, Cu, Pb, and Zn in Oyster (Saccostrea cucullata) from Qeshm Island Coast in Persian Gulf: Implications of Provisional Maximum Tolerable Daily Intake (PMTDI)

Concentrations of heavy metals (Cd, Cu, Pb, and Zn) were determined in soft tissue of 122 rock oyster (Saccostrea cucullata) collected at seven stations from the coastal zones of Qeshm Island. The exposure of the consumer is compared directly to maximum residue level and provisional maximum tolerable daily intake. Result indicated that levels of Cd, Pb, and Cu were within limits, but the level of Zn exceeded that the limit. Concentrations of Zn (1168.71 μg g−1) and Cu (105.16 μg g−1) were comparatively higher than the level recommended in the international food standards, such as Brazilian Ministry of Health, National Health Medical Research Council, Ministry of Agriculture, Fisheries and Food, and the Tasmania Public Health Regulation. The results, therefore, indicate possible risk in consuming the oysters.

Evaluation of the Microalgal Substitute M-1 as a Diet for Juvenile Sydney Rock Oyster, Saccostrea glomerata (Gould 1850)

Evaluation of the Microalgal Substitute M-1 as a Diet for Juvenile Sydney Rock Oyster, Saccostrea glomerata (Gould 1850)

Differential effects of metal contamination on the transcript expression of immune- and stress-response genes in the Sydney Rock oyster, Saccostrea glomerata

Environmental contamination by metals is a serious threat to the biological sustainability of coastal ecosystems. Our current understanding of the potential biological effects of metals in these ecosystems is limited. This study tested the transcriptional expression of immune- and stress-response genes in Sydney Rock oysters (Saccostrea glomerata). Oysters were exposed to four metals (cadmium, copper, lead and zinc) commonly associated with anthropogenic pollution in coastal waterways. Seven target genes (superoxide dismutase, ferritin, ficolin, defensin, HSP70, HSP90 and metallothionein) were selected. Quantitative (real-time) PCR analyses of the transcript expression of these genes showed that each of the different metals elicited unique transcriptional profiles. Significant changes in transcription were found for 18 of the 28 combinations tested (4 metals × 7 genes). Of these, 16 reflected down-regulation of gene transcription. HSP90 was the only gene significantly up-regulated by metal contamination (cadmium and zinc only), while defensin expression was significantly down-regulated by exposure to all four metals. This inhibition could have a significant negative effect on the oyster immune system, promoting susceptibility to opportunistic infections and disease.

Assessing the risk of climate change to aquaculture: a case study from south-east Australia

A qualitative screening-level risk assessment was developed to evaluate relative lev- els of risk from climate change to aquaculture industries. The assessment was applied to 7 major industries in the temperate south-east region of Australia and involved a simple, transparent and repeatable methodology that was appropriate for a range of different aquaculture systems and taxa. Two key stages were involved: the development of comprehensive expertise-based litera- ture reviews or 'species profiles' and a scoring assessment, with the latter providing a defined framework within which industries could be ranked (from high to low risk). In addition to inform- ing the second stage of the risk assessment process, the species' profiles also highlighted impor- tant climate change drivers and key information uncertainties and knowledge gaps. There was good resolution among the scoring assessments, with only 2 industries receiving the same risk score. The results indicated that oysters farmed from wild spat (Sydney rock oysters Saccostrea glomerata) were at most risk to climate change, with warm temperate hatchery-based finfish spe- cies (yellowtail kingfish Seriola lalandi) being the least at risk. This study provides critical guid- ance for scientists, resource managers and stakeholders for future research, both in addressing key knowledge gaps and focussing the development of more detailed risk analyses for high risk aquaculture industries in south-east Australia.

Trace metals and rare earth elements in Rock Oyster Saccostrea cucullata along the east coast of Peninsular Malaysia

Trace metals and rare earth elements (REEs) in the soft tissue of rocky shore Rock Oyster, Saccostrea cucullata, along the east coast of Peninsular Malaysia were determined. Significant inter-spatial variations ( p &amp;lt; 0.05) in trace metals and REEs were recorded. Significant positive correlations ( p &amp;lt; 0.01) were found among REEs concentrations. A few significant correlations were found for trace metals and REEs. Average distribution of metals indicated that Johor State had the highest concentrations compared with Pahang and Terengganu for all metals, except for Pb and Cu. This could most likely be attributed to the highly urbanized and industrialized activities such as sewage discharge. The metal accumulation patterns in the oyster indicated enrichment of essential metals. Sites with relatively high concentrations of the contaminant metals Hg, Cu, Pb and Zn were related to their close proximity to industrial and urban sites or to boating and aquaculture activities. Relative enrichment of Cu, Pb and Zn in oysters in the whole study even from relatively pristine areas is thought to be derived from natural sources as these metals are significantly correlated to REEs distribution. The distribution of REEs show close similarity between all sampling sites, suggesting that they are of similar origins. In all sites, typical saw-tooth chondrite-normalized patterns were observed, which strongly suggested the REEs bioaccumulated in oyster tissues is derived from geogenic sources. Typical deviations from this pattern were found for Ce and Eu and could be explained by their redox chemistry. Results of light to heavy REEs (LREE/HREE) ratios suggested REEs fractionation in coastline marine environment produced more light REEs and less heavy REEs absorbed in the soft tissue of S. cucullata. The ratio of La/Yb in the oyster of 27.3 was remarkably similar to Terengganu River basin soil of 33.0 and to Terengganu River sediment of 27.6. Comparison of metal concentration with maximum permissible limits of toxic metals in food established in different countries, as well as Malaysian Food Act 1983 and Food Regulations 1985 Fourteen Schedule, indicated values were well within safety levels, except for Cu and Zn. Along with its wide distribution on rocky shore areas along the east coast, the present results of trace metals and REEs recorded in soft tissue of S. cucullata collected from 14 sites along the east coast of Peninsular Malaysia served as baseline data for future reference.

Impact of biofouling in intake pipes on the hydraulics and efficiency of pumping capacity

Colonization of cooling water systems (CWS) by fouling organisms is a major concern for industries, power, and desalination plants over the world. Biofouling results in, depending on the dimensions of the biofouling species and growth patterns, an increased wall roughness and reduction of the inner pipe diameter. This leads to a significant head loss in the intake structure. To prevent settlement and growth of fouling species, an effective antifouling treatment is required. However, fouling mitigation must be applied from early start of operation of an installation, as several species cannot be fully mitigated (chemically) or removed (physically) after settlement, as some of them (e.g. barnacles, the Japanese oyster and Rock oyster) cement themselves to the surface. This means that even after a physical cleaning, part of the organisms remains on the surface, resulting in an irreversible increased head loss and a decreased pump capacity. To provide some clearance on the impact of biofouling on pump capacity in CWS, two cases have been studied. The results show that nonoptimal fouling treatments result in significant additional annual energy consumption. Even after complete physical cleaning, the remaining head loss is above the design line due to the increased wall roughness and results in decreased pump capacity. The results strongly emphasize the necessity to apply an effective biofouling control during the start-up of a water intake system prior to commercial operation, or to have system design parameters which take into account the irreversible effects of biofouling.