Yungkul Kim

Application of a battery of biomarkers in mussel digestive gland to assess long-term effects of the Prestige oil spill in Galicia and Bay of Biscay: Tissue-level biomarkers and histopathology

In order to assess the biological effects of the Prestige oil spill (POS), mussels, Mytilus galloprovincialis, were collected in 22 localities along the North coast of the Iberian Peninsula over 3 years (April 2003-April 2006). Different tissue-level biomarkers including cell type composition (volume density of basophilic cells, Vv(BAS)) in digestive gland epithelium, structural changes of digestive alveoli (mean luminal radius to mean epithelial thickness, MLR/MET) and histopathological alterations (prevalence and intensity) of the digestive gland were analysed. Severe alterations in the general condition of the digestive gland tissue were observed all over the study area up to 2004-2005. High Vv(BAS) values were recorded mainly in Galicia but also to a lesser extent in the Bay of Biscay in 2003-2004. Atrophy of the digestive alveoli, measured in terms of MLR/MET, was detected all along the studied area up to 2006. Inflammatory responses cannot be related to pollution due to the POS: (a) prevalence and intensity of focal hemocytic infiltration were higher in the Bay of Biscay than in Galicia but they did not show a clear temporal trend; (b) high intensities of brown cell aggregates were only sporadically recorded; and (c) granulocytomas were more frequently recorded in the Bay of Biscay than in Galicia and especially in localities (i.e. Arrigunaga) subjected to chronic pollution. Likewise, Marteilia, trematodes, intracellular ciliates, unidentified eosinophilic bodies, R/CLO and Mytilicola did not follow any recognisable pattern that could be associated to the POS. In contrast, high Nematopsis intensities recorded in several localities in 2003 might suggest some response of local interest after the POS (i.e., in combination with particular factors/conditions). More data at a regional scale are needed before histopathology may provide a reliable ecosystem health assessment but the present results suggest that the approach is worthwhile. Overall, although Vv(BAS) returned to reference values by 2004-2005, MLR/MET values indicated that the mussel health condition was affected during the whole study period up to April 2006.

Parasites of sentinel bivalves in the NOAA status and trends program: distribution and relationship to contaminant body burden

The National Status and Trends Mussel Watch data for 1997 were used to compare the distribution of parasites between sentinel bivalves of the East, West, Gulf and Great Lakes coasts of the USA and to assess the relationship of parasitism to contaminant body burden. Overall, five patterns dominated the geographic distribution of the parasite fauna. (1) Certain parasites, such as Nematopsis, were principally associated with oysters from the southeast and Gulf coasts. (2) Discounting Nematopsis, oysters and mussels did not differ significantly in total parasite infection intensity. (3) West coast mussel populations were always lower in infection intensity than East coast mussels and rarely showed anything but a sporadic pattern of infection. (4) East coast mussels typically had a focus of infection in the Boston Harbor region. (5) With the exception of Nematopsis, mussels on the West coast, Mytilus edulis and Mytilus californianus, did not differ significantly in their parasite fauna. The geographic distributions of most parasites and disease-causing organisms varied independently. Any two parasites rarely co-occurred predictably over wide areas and never on more than one coast. Certain contaminants were correlated with certain parasites on one coast but not the other or in one bivalve type but not another. Statistics that emphasized infection intensity found significant relationships between parasitism and contaminant body burden most often in East and Gulf coast oysters and West coast mussels and, in most cases, higher body burdens were associated with lower infection intensities. Statistics that emphasized prevalence also identified significant relationships most often in East and Gulf coast oysters and West coast mussels. In contrast to infection intensity, most significant results occurred because parasites were observed more often in locales characterized by higher contaminant body burdens. In no case was a parasite/ contaminant pair significant for both infection intensity and prevalence.

DISTRIBUTION OF PARASITES AND PATHOLOGIES IN SENTINEL BIVALVES: NOAA STATUS AND TRENDS “MUSSEL WATCH” PROGRAM

Abstract The 1995–1998 histopathology data from NOAAs Mussel Watch Program were analyzed to: (1) document the occurrence of parasites and pathologies in sentinel bivalves during the 1995–1998 time period, (2) describe and compare the geographic distribution of these parasites and pathologies between different bivalve species and between different geographic regions, and (3) evaluate trends in parasite taxon richness. Parasite taxon richness was higher in oysters than in mytilids and dreissenids. Parasites having higher prevalences in a given host taxon routinely also had higher infection intensities. When different geographic locations were compared, the same trends occurred much more rarely. Oysters were more heavily infected based on total parasite body burden than mytilids, and the frequency of hosts with at least one parasite was higher. Excluding the numerically-dominant gregarines, however, removed the differential between oysters and mytilids, with the exception of East-coast mytilids that were more frequently parasitized than East-coast oysters. Dreissenids had lower prevalence and infection intensity for all parasites than the other host bivalve taxa. Though cestodes offer a discrepancy, most of the more common oyster parasites were unicellular, whereas most of the more common mytilid parasites were multicellular. On the average, parasite distributional patterns along a stretch of coastline were more often clinal in nature in mytilids, in that prevalence and infection intensity tended to change gradually over relatively large distance scales, and more bounded in nature in oysters, in that prevalence and infection intensity tended to change more sharply over shorter distance scales. Latitudinal trends were diametric opposites on the two northern coasts. More parasites occurred in mytilids from northern bays of the East coast, whereas fewer occurred in mytilids from northern bays of the West coast. Mytilids far exceeded oysters in the incidence of pathologies, including digestive gland and gonadal abnormalities and hemocytic infiltration. On the West coast, the vast majority of these pathologies occurred in mussels of the Mytilus edulis complex rather than M. californianus. All pathologies were more common in mytilids from the northeast coast than in West-coast mytilids. Indeed, discounting the gregarines, northeast coast mytilids combined the highest instances of pathologies with among the highest parasite body burdens of any bivalve taxon and coastal area combination in the Mussel Watch program.

Geographical trends in weight and condition index of surfclams (Spisula solidissima) in the Mid-Atlantic Bight.

ABSTRACT A survey of surfclam (Spisula solidissima) stocks was conducted in an area from northern New Jersey to southern Virginia during June and July 2004 to evaluate the progress of mortality, apparently related to warming of the Mid-Atlantic Bight. One component of the survey was the measurement of condition index at 146 locations from the Delmarva Peninsula to northern New Jersey. The program followed a pilot study in 2002 that suggested that surfclam mortality off Delmarva was likely caused by warmer temperatures that decreased feeding and subsequently led to starvation. Condition index was highest inshore, with the exception of a few of the most inshore stations, and lowest at the offshore edge of the clams range. An estimate of meat weight for a standard 120-mm clam, from site-specific length—weight regressions, revealed that the animals near the center of the inshore— offshore distribution had a greater weight per length than those living at the edges of the clams range, probably a result of the influence of temperature on feeding and growth. Low condition in the extreme inshore locations suggests that warmer temperatures continue to affect surfclam nutrition negatively and indicates the continued susceptibility of clams along the southern and inshore range boundary to warming in the Mid-Atlantic Bight. Low condition offshore may be the result of a delay in gametogenesis or inadequate nutrition resulting from low temperatures reducing feeding rate and food supply.

Influence of climate change on interannual variation in contaminant body burden in Gulf of Mexico oysters

Abstract As part of NOAAs National Status and Trends Mussel Watch Program, oysters were sampled along the Gulf of Mexico coast each winter from 1986 to 1992 and analyzed for trace metal, polynuclear aromatic hydrocarbon (PAH), and pesticide body burden. We identified contaminant variables for which large-scale climate processes played an important role in establishing the interannual variation in body burden by examining cases where body burdens rose or fell more or less in unison over broad geographic regions and distinguished these concordant changes from cases where bays varied independently. Of the 11 metals analyzed, nine had scales of concordancy ⩽100 km. Ni and Se, however, had among the largest scales of concordancy in the study, ⩾1200 km. That is, oyster body burdens in bays as far apart as 1200 km tended to rise and fall in unison from one year to the next. Interannual variations in body burden of organic contaminants had a much stronger regional component. All but two of the 11 organic contaminants had scales of concordancy of 200 km or greater and six exceeded 400 km. Concordancy was strongest either in the southern, northwestern, or north-central Gulf, depending upon the contaminant. For all contaminants, bays tended to vary independently in the northeastern Gulf. For three contaminants, total chlordanes, dieldrin and Cd, regional concordancy may originate from a widespread decrease in use and, therefore, input. These contaminants declined nearly monotonically over the 7 years. For others, including Zn and many of the PAHs and pesticides, the El Nino/Southern Oscillation (ENSO) cycle may be important in establishing the interannual variability in contaminant body burden: (1) ENSO has the geographic scale required; (2) a subtropical influence is required to explain the similarity in interannual variation between south Texas and southern Florida; (3) ENSO-related climate responses in the Gulf follow the southwestern/northeastern trend that would establish the northwestern Gulf focus in concordancy so prominent in many of the contaminants; and (4) deviations in yearly mean body burden from the Gulf-wide mean track the Southern Oscillation Index in some cases.

Effects of Gas‐Producing Platforms on Continental Shelf Megafauna in the Northwest Gulf of Mexico: Reproductive Status and Health

One component of the Gulf of Mexico Offshore Operations Monitoring Experiment (GOOMEX) was to assess the reproductive effort and health (defined as the prevalence and intensity of parasites or pathologies) of mobile macroepifauna collected near-to and far-from gas-producing platforms. The stage of reproductive development as determined by visual inspection or histological analysis was rarely significantly different between near-field and far-field sites. Tissues were examined histologically to determine the prevalence and intensity of parasitism and disease. If a difference in parasitism or pathology existed, individuals collected far-from the platforms typically had higher prevalences while individuals living near-to the platforms usually had higher intensities. Parasitism and disease had little effect on stage of reproductive development except at MU-A85 where individuals with increased disease and parasitism also had decreased reproductive development. Variations in infection intensity were not due to differences in age structure of populations. Larger, older individuals were not consistently more heavily parasitized. Trend in reproductive stage and population health did not follow trends in environmental contamination; the fewest significant differences were observed at the most contaminated platforms. Patterns of differences in parasitism, disease and reproductive effort between the near and far-field stations were platform specific, indicating that the physical and chemical characteristics unique to each platform probably control reproductive effort and levels of disease and parasitism in populations living there. The influence of structure, a variable common to all platforms, did not exert an overriding influence. Mobile taxa such as shrimp exhibited near-field/far-field differences as frequently as the less mobile species such as starfish. Thus, mobile epifauna maintain discrete populations over long-enough time periods to develop different population histories. Shallow-water sites were more likely to exhibit platform-specific near-field/far-field differences in population structure suggesting that trends in water depth and the intensity of seasonality may explain the apparent uniqueness of each platforms effect on population structure and health.

Effects of Climate Variability on Interannual Variation in Parasites, Pathologies, and Physiological Attributes of Bivalves from the U.S. East, Gulf, and West Coasts

We analyzed weighted prevalence of various parasites and pathologies for 1995 to 2006 along with a set of physiological variables to determine the degree of concordancy in their interannual variations over 500-km stretches of coastline using data from the National Oceanic and Atmospheric Administrations (NOAAs) National Status and Trends “Mussel Watch” Program. The variables examined in mytilid mussels fell into three groups based on the temporal patterns observed: ceroid bodies, taxon richness, digestive tubule atrophy, and major pathologies varied concordantly along the Northeast and West Coasts. For reproductive stage, sex ratio, and gill ciliates, concordant temporal trends were limited to the northeast coast. Gregarines, found only in West coast mussels, behaved similarly to those variables falling into the first group. A final group, trematode metacercariae and sporocysts, tissue pathologies, and the prokaryotes, was characterized by limited concordancy. For oysters, a similar triplet of groups wa...

Temporal Structure and Trends of Parasites and Pathologies in U.S. Oysters and Mussels: 16 Years of Mussel Watch

ABSTRACT Parasites and pathologies of oysters and mussels were sampled yearly from 1995 to 2010 from the Gulf of Maine to Alaska and the Great Lakes as part of the National Oceanic and Atmospheric Administration Status and Trends Mussel Watch Program. Sentinel bivalves included mytilid mussels, dreissenid mussels, and oysters. This comprehensive dataset provides a unique opportunity to examine long-term temporal dynamics of parasites, pathologies, and physiological indices of these sentinel bivalves. Temporal dynamics fell into a few clear categories. Significant differences between years occurred commonly for parasites, pathologies, and physiological indices; the absence of significant change over time was more noteworthy. In a few cases, these trends were characterized by multiyear increases or decreases in value within the time series. Such behavior might be produced by a multiyear cycle and, in fact, such behavior was much more common along the southern East Coast, the Gulf Coast, and Southern California where a relatively short cycle, El Niño-Southern Oscillation (ENSO), is well documented. More interestingly, for a number of parasites, pathologies, and physiological indices, significant trends existed across the time series. These trends substantively exceed the time span of climate cycles influencing these regions such as ENSO and the North Atlantic Oscillation. A few of these longer term coherent trends were continental in scale, being observed across sentinel taxa and multiple coasts. Continental scale trends were restricted to the physiological indices such as length. Regional trends were important for a subset of parasites, pathologies, and physiological indices. In general, the regional trends were produced by single-celled proliferating parasites such as Perkinsus marinus, the major pathologies, and certain physiological indices. The multicellular eukaryotes and the gregarines often showed significant year-to-year changes without trend. Temporal trends were prominently represented by oyster parasites on the Atlantic and Gulf Coasts and by mytilid parasites on the West Coast. Pathologies by contrast had strong temporal signals in northeastern mytilids.

Widespread survey finds no evidence of Haplosporidium nelsoni (MSX) in Gulf of Mexico oysters

The advent of molecular detection assays has provided a set of very sensitive tools for the detection of pathogens in marine organisms, but it has also raised problems of how to interpret positive signals that are not accompanied by visual confirmation. PCR-positive results have recently been reported for Haplosporidium nelsoni (MSX), a pathogen of the oyster Crassostrea virginica in 31 of 40 oysters from 6 sites in the Gulf of Mexico and the Caribbean Sea. Histological confirmation of the PCR results was not undertaken, and no haplosporidian has been reported from the numerous histological studies and surveys of oysters in the region. To further investigate the possibility that H. nelsoni is present in this region, we sampled 210 oysters from 40 sites around the Gulf of Mexico and Puerto Rico using PCR and 180 of these using tissue-section histology also. None of the oysters showed evidence of H. nelsoni by PCR or of any haplosporidian by histology. We cannot, therefore, confirm that H. nelsoni is present and widespread in the Gulf of Mexico and the Caribbean Sea. Our results do not prove that H. nelsoni is absent from the region, but taken together with results from previous histological surveys, they suggest that for the purposes of controlling oyster importation, the region should continue to be considered free of the parasite.

The allometry of oysters: spatial and temporal variation in the length–biomass relationships for Crassostrea virginica

We examine the relationship of biomass B and length L in the eastern oyster Crassostrea virginica by focusing on the scaling exponent b in the allometric equation B = aL b using four datasets: Delaware Bay, Chesapeake Bay, Galveston Bay and a regionally extensive compilation from the NOAA Mussel Watch Program. The average value of the scaling exponent in Delaware Bay and Chesapeake Bay is about 2. For Galveston Bay, the value is distinctly higher, near 2.6. Over all Mussel Watch sites, the value is again near 2. Within Delaware Bay, the salinity gradient exerts an important effect. Shells are longer for their meat weight at lower salinities. The range of scaling exponents revealed by Mussel Watch data is exceedingly large ( b 3). Scaling exponents below 2.5 are unusual in bivalves. Among bivalves, only other oyster taxa have comparably low scaling exponents averaging near 2. We propose that oyster biomass routinely scales nearer the square of the length rather than the cube and that this is a constraint imposed by the exigency of carbonate production for reef maintenance and accretion in the face of high rates of taphonomic degradation. The adaptation as a reef builder requires the formation of carbonate that rapidly breaks down, thus requiring that carbonate produced be maximized. A biomass-to-length scaling exponent of 2 provides a mechanism to maximize shell production relative to biomass, while at the same time providing maximum surface area for the all-important settling of oyster spat to maintain the population.