Marine Water Species Research Articles

Salinity tolerance of Nile tilapia (Oreochromis niloticus) to seawater and growth responses to different feeds and culture systems

The inability to acclimatise, feed and grow Nile tilapia (Oreochromis niloticus) in full seawater salinity has been a major obstacle to farming in marine waters. We investigated the salinity tolerance of O. niloticus and growth responses to different feeds and culture systems. Fish were first acclimatised to different salinities in laboratory aquaria, and the survival and growth performance in sea water were then assessed in aquaria, cages and ponds. Acclimatization to seawater salinity (5 – 30) took place at a rate of 5 every 9 days. Fish were stocked at densities of 5 fish/20 L in aquaria, 5 fish/m2 in cages and 3 fish/m2 in ponds. Replicates of 5, 3 and 3 were performed in aquaria, cages and ponds, respectively. Fish were fed on commercial (1 and 2) and locally formulated (30 % crude protein) diets. Mortality rates were higher in aquaria, when fish were introduced to salinities between 5 and 30 over 24 hours. Gradual salinity adjustments attained a stable survival rate of 78 % at salinities above 30. Aquarium experiments indicated significant negative correlation between salinity and survival (p < 0.001, r = 0.387) and daily growth rates varied with diet (0.01 – 0.05 g/day). Acclimatized fish showed minimal mortality in ponds and cages. Daily growth rates varied with diet and culture system; 0.54 - 2.48 g/day in cages and 1.1 - 2.5 g/day in ponds. Fish fed on commercial feed 2 showed significant growth rates for all culture methods (p < 0.05). O. niloticus could be fully acclimatised to seawater and attained promising growth rates when subjected to different commercial diets indicating potential of farming the species in marine waters.

Commercial production of Florida pompano (Trachinotus carolinus) larvae at low salinity induces variable changes in whole-larvae microbial diversity, gene expression, and gill histopathology

IntroductionSalinity presents economic and technical challenges in land-based recirculating aquaculture systems (RAS) in the U.S. warm water marine finfish aquaculture industry. Many studies have shown euryhaline fish reared at salinities closer to their iso-osmotic salinity can yield enhanced production performance as well as potential reduced costs to farms. However, there is potential for osmotic stress in fish larvae to negatively impact larvae microbiome and innate immune system. Florida pompano (Trachinotus carolinus) is a popular sportfish has been targeted for land-based RAS due to its impressive market value and euryhaline capacity. This study investigated the impacts of rearing Florida pompano larvae at salinities closer to their iso-osmotic salinity.Materials and methodsLarvae were cultured at 10, 20, and 30 ppt in triplicates, and larvae samples were collected for histopathology, microbiome, and whole transcriptomics analysis every three days from hatching until the time of weaning (24 days post hatch [DPH]). Water samples were also taken for microbiome analysis on every other larval sampling day. DiscussionThese changes were driven more by metamorphosis, causing an increase in expression of antioxidant genes (cat, gss, gsto1, and scara3) than by the presence of potentially pathogenic genera, which failed to induce an immune response (low or unchanged expression of downstream elements of the NOD1 or TLR5 pathways). These findings provide baseline information on Florida pompano low salinity tolerance in larviculture during early developmental stages. In addition, we have shown minimal effects on the immune system at salinities as low as 10 ppt. This work has important implications for larval health management and can be used to refine and direct future research regarding improving commercial production of warm water marine species

A descriptive study of ciguatera fish poisoning in Cook Islands dogs and cats: Exposure history, clinical signs, and formulation of a case definition.

Background and Aim:Ciguatera fish poisoning (CFP) is a multisystem toxicosis caused by the ingestion of warm water marine species. Dogs and cats are susceptible to CFP, but there is little published and much unknown about the condition in these species. This study aims to describe the syndrome of CFP in dogs and cats and to develop a case definition.Materials and Methods:Six years (March 2011-February 2017) of medical records from the Esther Honey Foundation Animal Clinic (the only veterinary clinic in the Cook Islands during the study period) were reviewed to identify cases of CFP. Data relating to exposure history and clinical signs were collected.Results:Two hundred forty-six cases of CFP were identified, comprising 165 dogs and 81 cats. Fish ingestion was documented in 29% of cases. Reef/lagoon fish and moray eels were most commonly implicated. The toxicosis was characterized by motor dysfunction with a high frequency of ataxia and paresis/paralysis/recumbency. Respiratory and gastrointestinal systems were also affected, especially in canine CFP cases. A multi-tiered case definition and a diagnostic algorithm for CFP in dogs and cats were developed based upon the findings of this study and a review of the existing literature.Conclusion:This case series is the largest study of canine and feline CFP to date. It documents the exposure history of cases and describes in detail clinical signs of the toxicosis. It also proposes a system of case classification that has the potential to both assist the diagnosis of CFP and facilitate future surveillance and research activities.

Fish market infrastructure in Khulna city, Bangladesh

An investigation was carried out on fish market infrastructure of Khulna district to identify the infrastructure facilities of domestic fish market including species traded along with price and also to detect the constraints at different levels of trading recommending possible solutions according to standards. The investigation was conducted from November 2016 to June 2017 in three different markets of Khulna district namely Sandhya Bazar fish market, Aranghata Bypass Bazar fish market and Baikali Bazar fish market. In Khulna, a large number of people are involved in fish marketing. Market infrastructures of Khulna had grown up according to various influencing factors that controls the total system involved. The study was based on observation and field survey. Data were collected through eye observation, questionnaire interviews and focus group discussions. Several number of market agents including wholesalers, retailers were selected for questionnaire interviews and aratdars and fishermen were selected for focused group discussions. It was revealed that the infrastructure facilities were inadequate and poorly maintained. Fish sheds were not enough hygienic to protect the fish from contamination. Surface water drainage system was open and this situation degraded further environmental condition of the markets. Electricity maintenance was not up to the mark and there were no distillation process for the supplied water. This infrastructural condition does not support a hygienic condition for fish marketing to provide edible and quality fish. Total number of freshwater fish species traded in different markets was found 60 including 12 SIS, 34 culture and 14 capture. On the other hand 41 brackish and marine water species were found and 14 crustacean species of which 5 were freshwater prawn, 6 brackish water shrimp and 3 crabs. Therefore domestic market infrastructure is on a developing stage as being controlled by Khulna City Corporation (KCC). Establishment of ice factory, improvement of fish transport facilities, introduction of fish quality control measures were suggested to improve the fish marketing in the study area.
 Asian Australas. J. Biosci. Biotechnol. 2020, 5 (1), 122-134

Efecto del cadmio sobre la concentración y expresión de la proteína TNF-α en el erizo marino Diadema setosum (Leske, 1778)

Background: Cadmium (Cd) is a toxic heavy metal present in seawater, and can damage DNA, producing lipid peroxidation, and protein inactivation. Goals: This research aimed to investigate the effect of Cd on the concentration and expression of TNF-α protein in the Diadema setosum. Methods: This study was conducted for 4 weeks in the laboratory of Marine Conservation LIPI Ambon. Experimental Cd concentrations were 0.0, 1.0, 3.0, 6.0, 9.0, and 12.0 μg/L. The experiment was conducted in 6 tanks (100 x 60 x 70 cm3) each one with 7 individuals of D. setosum as 7 biological replicates. The examination of activation and concentration of TNF-α was performed with immunohistochemical techniques as well as indirect ELISA and western blotting at the Laboratory of Medical Physiology of Brawijaya University. The data related to TNF-α protein concentrations were analyzed by one way ANOVA and a Duncan test (p < 0.05). Results: The results showed that Cd treatment significantly increased the levels of TNF α protein. There is a linear relationship between Cd concentration and TNF-α protein levels. The level of the TNF- α protein at the concentration of 12 μg/L Cd was the highest. Conclusions: The results of this research on the concentration and presence of TNF-α protein indicate that this approach could be implemented as a biomonitoring model of the exposure to Cd at the molecular level using D. setosum as bioindicator species in marine waters.

A new signal of marine tropicalization in the Macaronesia region: First record of the mesophotic macroalga Avrainvillea canariensis A. Gepp & E.S. Gepp in the Madeira archipelago

Mesophotic green algal meadows of Avrainvillea canariensis are firstly reported for Madeira island. This represents a northern expansion of the species by nearly 500 km turning the species a Macaronesian endemism. The meadows of A. canariensis were found in a sandy bottom in the South coast of the island of Madeira, inside the Marine Park of Cabo Girão, covering an estimated area of 50 m2 at a depth range 25–30 m. The collected specimens reached about 12 cm in height and were found clustered, forming distinct patches. Since this type of subtidal surveys in soft bottoms are scant in Madeira, we cannot evaluate whether this is a recent colonization. Yet, this new record can be another clear sign of climate change effects in the madeiran benthic communities, a process previously documented in the Macaronesia region with the arrival and subsequent settlement of other warm water marine species.

Retrievals of phytoplankton community structures from in situ fluorescence measurements by HS-6P.

Phytoplankton community is an important organism indicator of monitoring water quality, and accurately estimating its composition and biomass is crucial for understanding marine ecosystems and biogeochemical processes. Identifying phytoplankton species remains a challenging task in the field of oceanography. Phytoplankton fluorescence is an important biological property of phytoplankton, whose fluorescence emissions are closely related to its community. However, the existing estimation approaches for phytoplankton communities by fluorescence are inaccurate and complex. In the present study, a new, simple method was developed for determining the Chlorophytes, Chrysophytes, Cryptophytes, Diatoms, Dinoflagellates, and Prymnesiophytes based on the fluorescence emission spectra measured from the HOBI Labs Hydroscat-6P (HS-6P) in the Bohai Sea, Yellow Sea, and East China Sea. This study used single bands, band ratios, and band combinations of the fluorescence signals to test their correlations with the six dominant algal species. The optimal band forms were confirmed, i.e., X1 (i.e., fl(700), which means the fluorescence emission signal at 700 nm band) for Chlorophytes, Cryptophytes, Dinoflagellates, and Prymnesiophytes (R = 0.947, 0.862, 0.911, and 0.918, respectively) and X7 (i.e., [fl(700) + fl(550)]/[fl(550)/fl(700)], where fl(550) denotes the fluorescence emission signal at 550 nm band) for Chrysophytes and Diatoms (R = 0.893 and 0.963, respectively). These established models here show good performances, yielding low estimation errors (i.e., root mean square errors of 0.16, 0.02, 0.06, 0.36, 0.18, and 0.03 for Chlorophytes, Chrysophytes, Cryptophytes, Diatoms, Dinoflagellates, and Prymnesiophytes, respectively) between in situ and modeled phytoplankton communities. Meanwhile, the spatial distributions of phytoplankton communities observed from both in situ and fluorescence-derived results agreed well. These excellent outputs indicate that the proposed method is to a large extent feasible and robust for estimating those dominant algal species in marine waters. In addition, we have applied this method to three vertical sections, and the retrieved vertical spatial distributions by this method can fill the gap of the common optical remote sensing approach, which usually only detects the sea surface information. Overall, our findings indicate that the proposed method by the fluorescence emission spectra is a potentially promising way to estimate phytoplankton communities, in particular enlarging the profiling information.

Thermal biases and vulnerability to warming in the world's marine fauna.

A critical assumption underlying projections of biodiversity change associated with global warming is that ecological communities comprise balanced mixes of warm-affinity and cool-affinity species which, on average, approximate local environmental temperatures. Nevertheless, here we find that most shallow water marine species occupy broad thermal distributions that are aggregated in either temperate or tropical realms. These distributional trends result in ocean-scale spatial thermal biases, where communities are dominated by species with warmer or cooler affinity than local environmental temperatures. We use community-level thermal deviations from local temperatures as a form of sensitivity to warming, and combine these with projected ocean warming data to predict warming-related loss of species from present-day communities over the next century. Large changes in local species composition appear likely, and proximity to thermal limits, as inferred from present-day species' distributional ranges, outweighs spatial variation in warming rates in contributing to predicted rates of local species loss.

Investigation on Fish Marketing System and Species Availability at Daulatpur Fish Market in Khulna, Bangladesh (Revised)

16th February 2015. Due to a number of missing tables and figures, this article (DOI: http://dx.doi.org/10.3329/jesnr.v7i1.22144) was withdrawn from Vol.7(1) and has been republished with corrections in Vol.7(2) pp.177-184 (DOI: http://dx.doi.org/10.3329/jesnr.v7i2.22228).An investigation was carried out on the fish marketing system and availability of fish species at Daulatpur fish market in Khulna over 12-months from September 2012 to August 2013. Combinations of the participatory, qualitative and quantitative methods were used for questionnaire interviews for data collection. A total of 115 species of fresh water, brackish and marine water fish and crustacean species were identified during the observation period. The number of fresh water fish species was found 60 including 14 fresh water culture species and 12 SIS whereas brackish and marine water species was found 41 and crustacean species was 14 including 5 fresh water prawn, 6 marine and brackish water shrimp and 3 crabs. During the observation period, it was found that the availability of culture fish species was higher in the market and it was 55.86% including 17% catfish, 15.65 % tilapia, 15.56 % carp fishes, 4.18% koi, 2.47% punti and 1% prawn. Catfish, carps, tilapia, snakehead, baim, shing-magur, punti, koi etc were the major abundant groups among the fresh water fish species whereas ilish and some shrimp were the abundant species of marine and brackish water fish. The highest abundance (55.86%) was found the fresh water culture fish species following to marine and brackish water species (28.01%) and fresh water capture species (16.01%). The market chain from farmers/fishermen to consumers encompassed mainly primary, secondary and retail markets involving local agents (foria and bepari) suppliers, aratdars, wholesalers and retailers. During the observation, it was found that the auctioneers get 3 to 5% commission by performing their activities. Aratdars also get 4 to 5% commission due to arrange auctioning activities and providing other facilities such as clean water supply, electricity, space, communication etc which is called aratdary. In some cases farmers have to pay market tools that locally called khazna which vary from 5 to 10% depending on amount of sales. Market structure, species quality, size and weight have an influence on the price of fish and it was found that the price of fish increases per kilogram with increasing size and it varied with species to species. Every step of intermediaries of marketing channel obtained certain amount of profit and ultimately the farmers/fishermen received an average near about 60 percent of the retail price of fish in the market.DOI: http://dx.doi.org/10.3329/jesnr.v7i2.22228 J. Environ. Sci. &amp; Natural Resources, 7(2): 177-184 2014

Investigation on Fish Marketing System and Species Availability at Daulatpur Fish Market in Khulna, Bangladesh

16 th February 2015. Due to a number of missing tables and figures, this article (DOI: http://dx.doi.org/10.3329/jesnr.v7i1.22144 ) was withdrawn from Vol.7(1) and has been republished with corrections in Vol.7(2) pp.177-184 (DOI: http://dx.doi.org/10.3329/jesnr.v7i2.22228 ). An investigation was carried out on the fish marketing system and availability of fish species at Daulatpur fish market in Khulna over 12-months from September 2012 to August 2013. Combinations of the participatory, qualitative and quantitative methods were used for questionnaire interviews for data collection. A total of 115 species of fresh water, brackish and marine water fish and crustacean species were identified during the observation period. The number of fresh water fish species was found 60 including 14 fresh water culture species and 12 SIS whereas brackish and marine water species was found 41 and crustacean species was 14 including 5 fresh water prawn, 6 marine and brackish water shrimp and 3 crabs. During the observation period, it was found that the availability of culture fish species was higher in the market and it was 55.86% including 17% catfish, 15.65 % tilapia, 15.56 % carp fishes, 4.18% koi, 2.47% punti and 1% prawn. Catfish, carps, tilapia, snakehead, baim, shing-magur, punti, koi etc were the major abundant groups among the fresh water fish species whereas ilish and some shrimp were the abundant species of marine and brackish water fish. The highest abundance (55.86%) was found the fresh water culture fish species following to marine and brackish water species (28.01%) and fresh water capture species (16.01%). The market chain from farmers/fishermen to consumers encompassed mainly primary, secondary and retail markets involving local agents (foria and bepari) suppliers, aratdars, wholesalers and retailers. During the observation, it was found that the auctioneers get 3 to 5% commission by performing their activities. Aratdars also get 4 to 5% commission due to arrange auctioning activities and providing other facilities such as clean water supply, electricity, space, communication etc which is called aratdary. In some cases farmers have to pay market tools that locally called khazna which vary from 5 to 10% depending on amount of sales. Market structure, species quality, size and weight have an influence on the price of fish and it was found that the price of fish increases per kilogram with increasing size and it varied with species to species. Every step of intermediaries of marketing channel obtained certain amount of profit and ultimately the farmers/fishermen received an average near about 60 percent of the retail price of fish in the market. DOI: http://dx.doi.org/10.3329/jesnr.v7i2.22228 J. Environ. Sci. & Natural Resources, 7(2): 177-184 2014

Solid-State NMR Study of Intact Microalgae

The study of intact cells by solid-state NMR is challenging considering their high level of complexity. Therefore interactions with the lipid membranes for example have been traditionally studied using model cell membranes composed of a few representative lipids. Microalgae are excellent examples of the complexity of microorganisms. Their lipid-rich plasma membrane is, in most species, protected by a cell wall, and the cytoplasm contains a variety of organelles including the chloroplast and the nucleus, as well as storage lipids and sugars. Microalgal cell walls are diverse and can be made of cellulose, proteins, polysaccharides, silica or calcium carbonate. The diversity of lipids is also notable in terms of the headgroup variety encountered as well as degrees of unsaturation. Because microalgae are at the basis of the aquatic food chain, we are developing approaches to study the interaction of contaminants with these cells by solid-state NMR using magic-angle spinning (MAS) for maximum resolution. We have first established a protocol of 13C enrichment, enabling the acquisition of signal from all the constituents. Freshwater C. reinhardtii and marine water species P. lutheri and N. galbana have thus been 13C-labeled. The use of dynamic filters to evidence particular constituents will be discussed, such as experiments based on through-space (cross polarization) or through-bond (RINEPT) magnetization transfer to study rigid and dynamic components, respectively. Isotopic labeling strategies will also be discussed as well as the challenges to study interactions with the lipid membranes and cell wall.

Geographic isolation and physiological mechanisms underpinning species distributions at the range limit hotspot of South Georgia

In order to allocate quotas for sustainable harvests, that account for climate warming, it is important to incorporate species vulnerabilities that will underlie likely changes in population dynamics. Hotspots, regions with rapidly changing climate, are important locations for rapid advances in mechanistic understanding of the factors driving these changes, particularly if they coincide with regions with a high incidence of range limits, such as the sub-Antarctic Island of South Georgia. This archipelago is at the Northern limit of the Southern Ocean and therefore the northern distribution limit for many Southern Ocean shallow water marine species, which are amongst the most sensitive fauna to increasing temperature. At range limits species may either be living close to their physiological limits, or they may have more resistant phenotypes. In case studies, the northern range limit population of the gastropod limpet, Nacella concinna, has greater physiological plasticity at South Georgia than those from further south, allowing them to cope better with the warmer and more variable seasonal temperatures. Bivalve species, however, alter their depth distributions at South Georgia, to avoid the warmer water masses, indicating that they may not be able to cope with the warmer temperatures. Mackerel icefish, Champsocephalus gunnari, has a unique Antarctic trait, the loss of haemoglobin. A combination of temperature driven change in food web structure, and this extreme physiological cold adaptation, may explain why rapid warming at its northern range limit of South Georgia, has prevented stocks fully recovering from over fishing in the 1980s, despite highly conservative management strategies.

Comparative study of proximate composition, amino and fatty acids of some economically important fish species in Lagos, Nigeria

The proximate composition, amino and fatty acids of four economically important fish species from the lagoons and off Lagos coast around Lagos, Nigeria were determined over a period of two years. The mean proximate composition of the freshwater species were 19.64% protein, 1.15% lipid, 76.71% moisture and 1.23% ash for Clarias gariepinus; 19.55% protein, 0.96% lipid, 76.75% moisture and 1.11% ash for Tilapia zillii. The mean proximate composition of the marine water species were 19.80%, protein, 0.40% lipid, 72.63% moisture and 1.13% ash for Pentanemus quinquarius and 19.86% protein, 1.06% lipid, 75.40% moisture and 1.17% ash for Pseudotolithus typus. Nine essential amino acids namely lysine, leucine, valine, isoleucine, threonine, phenylalanine, methionine, tryptophan and histidine that are very important for human health were present in all the species examined. The highest total amino acids value of 179.74 mgg-1 was recorded in P. typus. The concentration of the total lipids, fatty acids, saturated, monounsaturated and polyunsaturated fatty acids levels were not the same within as well as between species. For the saturated fatty acids, palmitic acid had the highest proportion while oleic acid was the main monounsaturated fatty acid. Docosahexaenoic and eicosapentaenoic acids were the dominant polyunsaturated fatty acids in all the species. The results indicate that the fish species had high quality protein, essential amino acids and fatty acids. Overall, C. gariepinus appears to be the best diet for its relatively high nutrient components and the ratio of polyunsaturated: saturated fatty acid is followed by P. typus, P. quinquarius and T. zillii. Key words: Proximate, freshwater, marine, fatty acids, amino acids, Nigeria.

Fish trophic level and the similarity of non-specific larval parasite assemblages

Whereas the effect of parasites on food webs is increasingly recognised and has been extensively measured and modelled, the effect of food webs on the structure of parasite assemblages has not been quantified in a similar way. Here, we apply the concept of decay in community similarity with increasing distance, previously used for parasites in geographical, phylogenetic and ontogenetic contexts, to differences in the trophic level (TL) based on diet composition of fishes. It is proposed as an accurate quantitative method to measure rates of assemblage change as a function of host feeding habits and is applied, to our knowledge for the first time, across host species in marine waters. We focused on a suite of 15 species of trophically-transmitted and non-specific larval helminths across 16 fish species (1783 specimens, six orders, 14 families) with different sizes and TLs, gathered from the same ecosystem. Not all host species harboured the same number and types of parasites, reflecting the differences in their ecological characteristics. Using differences in TL and body length as measurements of size and trophic distances, we found that similarity at both infracommunity and component community levels showed a very clear decay pattern, based on parasite abundance and relative abundance, with increasing distance in TL, but was not related to changes in fish size, with TL thus emerging as the main explanatory factor for similarity of parasite assemblages. Furthermore, the relationships between host TL and assemblage similarity allowed identification of fishes for which the TL was under- or over-estimated and prediction of the TL of host species based on parasite data alone.

Post‐release survival of recreationally caught snapper, Pagrus auratus, in Port Phillip Bay, south‐eastern Australia

Abstract Snapper, Pagrus auratus (Forester), is an important recreational species in marine waters of Victoria, Australia. This study estimated survival for compulsorily released undersized P. auratus by holding fish in cages and tanks for 3 days. In all, 620 P. auratus caught by angling were assessed for post‐release survival and 200 additional fish were used as controls. The survival rate was greater for shallow‐hooked (97%) than deep‐hooked (48%) P. auratus. Post‐mortems showed that hooking injuries to the throat and/or gill area caused most deaths, while piercing of the heart also caused mortalities. Removing deeply ingested hooks decreased survival. To estimate survival of P. auratus across the Victorian fishery, this study’s results should be combined with estimates of shallow‐hooking rates in the fishery. Shallow‐hooking rate estimates would quantify the impact of the low survival rate found for deep‐hooked fish.

Mercury sources, distribution, and bioavailability in the North Pacific Ocean: Insights from data and models

Fish harvested from the Pacific Ocean are a major contributor to human methylmercury (MeHg) exposure. Limited oceanic mercury (Hg) data, particularly MeHg, has confounded our understanding of linkages between sources, methylation sites, and concentrations in marine food webs. Here we present methylated (MeHg and dimethylmercury (Me2Hg)) and total Hg concentrations from 16 hydrographic stations in the eastern North Pacific Ocean. We use these data in combination with information from previous cruises and coupled atmospheric‐oceanic modeling results to better understand controls on Hg concentrations, distribution, and bioavailability. Total Hg concentrations (average 1.14 ± 0.38 pM) are elevated relative to previous cruises. Modeling results agree with observed increases and suggest that at present atmospheric Hg deposition rates, basin‐wide Hg concentrations will double relative to circa 1995 by 2050. Methylated Hg accounts for up to 29% of the total Hg in subsurface waters (average 260 ± 114 fM). We observed lower ambient methylated Hg concentrations in the euphotic zone and older, deeper water masses, which likely result from decay of MeHg and Me2Hg when net production is not occurring. We found a significant, positive linear relationship between methylated Hg concentrations and rates of organic carbon remineralization (r2 = 0.66, p &lt; 0.001). These results provide evidence for the importance of particulate organic carbon (POC) transport and remineralization on the production and distribution of methylated Hg species in marine waters. Specifically, settling POC provides a source of inorganic Hg(II) to microbially active subsurface waters and can also provide a substrate for microbial activity facilitating water column methylation.

Composition of Heads and Livers of Yelloweye Rockfish (Sebastes ruberrimus) Harvested in Alaska

Due to their large size and fillet quality, yelloweye rockfish (YER) are a highly prized species in both commercial and recreational Alaska fisheries. Processing yields for YER are relatively low, thus by-product volume is significant at up to 77% of whole fish weight (WFW). The objective of this research was to characterize yields and determine proximate composition, fatty acid (FA) and amino acid profiles, lipid classes, cholesterol content, and mineral composition of YER heads and livers. Heads of YER were the major by-product constituting 42% of WFW. YER livers made up only 2% of WFW. Livers contained high levels of lipids (28.5%) but were of small size, while lipid content of heads was 7.5%. Recovered oils were of high quality being predominantly triacylglycerols. Oils were similar in many aspects to oils from other demersal cold water marine finfish and were rich in omega-3 and omega-9 FA, and low in omega-6 FA. Protein content in heads and livers were 16% and 11.5%, respectively. Amino acid analysis revealed that the liver protein was of high quality. Mineral profile of livers was similar to values obtained from liver tissue from other cold water marine species. Overall, results indicated that YER by-products can be utilized for the production of good quality specialty ingredients that can be used as food and feed components.

Methylated Mercury Species in Marine Waters of the Canadian High and Sub Arctic

Distribution of total mercury (THg), gaseous elemental Hg(0) (GEM), monomethyl Hg (MMHg), and dimethyl Hg (DMHg) was examined in marine waters of the Canadian Arctic Archipelago (CAA), Hudson Strait, and Hudson Bay. Concentrations of THg were low throughout the water column in all regions sampled (mean +/- standard deviation; 0.40 +/- 0.47 ng L(-1)). Concentrations of MMHg were also generally low atthe surface (23.8 +/- 9.9 pg L(-1)); however at mid- and bottom depths, MMHg was present at concentrations sufficient to initiate bioaccumulation of MMHg through Arctic marine foodwebs (maximum 178 pg L(-1); 70.3 +/- 37.3 pg L(-1)). In addition, at mid- and bottom depths, the % of THg that was MMHg was high (maximum 66%; 28 +/- 16%), suggesting that active methylation of inorganic Hg(II) occurs in deep Arctic marine waters. Interestingly, there was a constant, near 1:1, ratio between concentrations of MMHg and DMHg at all sites and depths, suggesting that methylated Hg species are in equilibrium with each other and/or are produced by similar processes throughout the water column. Our results also demonstrate that oceanographic processes, such as water regeneration and vertical mixing, affect Hg distribution in marine waters. Vertical mixing, for example, likely transported MMHg and DMHg upward from production zones at some sites, resulting in elevated concentrations of these species in surface waters (up to 68.0 pg L(-1)) where primary production and thus uptake of MMHg by biota is potentially highest. Finally, calculated instantaneous ocean-atmosphere fluxes of gaseous Hg species demonstrated that Arctic marine waters are a substantial source of DMHg and GEM to the atmosphere (27.3 +/- 47.8 and 130 +/- 138 ng m(-2) day(-1), respectively) during the ice-free season.

Review of fundamentals and specific aspects of oxidation technologies in marine waters

This review is based on the existing literature and on our experiences in the application of different oxidation processes in brackish water and seawater. The oxidation reactions of advanced oxidation processes (AOPs) and the formation of disinfection byproducts (DBPs) are considerably different in marine waters from well-known drinking, process and wastewater applications. In contrast, the major secondary oxidants are bromine species in marine waters, which might form the DBPs of concern bromate and bromoform. An efficient AOP application needs knowledge of the source water constitutions and the oxidant demand. Besides changes in the oxidants chemistry compared to fresh water, the great and seasonal variation of marine waters has to be considered in the process design. The complexity of oxidant reactions and formation of byproducts are only partially researched and known as yet. Hence, it is advisable to determine the characteristic and variation of the water source as well as its influence on each AOP in experiments prior to the process design.

Determination of Inorganic Selenium Species in Marine Waters by Hydride Generation - AFS

A method based on hydride generation with cryogenic trapping and atomic fluorescence detection was developed that is capable of determining both inorganic Se species (SeIV and SeVI) while at sea. Evaluation of the system for optimal performance was made for each stage of the analysis and detection sequence, as well as for the SeVI reduction step. A detection limit of 0.4 ng L−1 Se in a 10 mL sample was achieved using this method. Precision was better than 3.5% for 25, 100, and 1000 ng L−1 SeIV standard solutions. Accuracy was determined by recovery studies using natural samples and a certified reference seawater (NASS-5).