Mummichog Fundulus Heteroclitus Research Articles

Scaling of fast-start performance and its thermal dependence in mummichog Fundulus heteroclitus.

Fast-start predator-escape performance and its sensitivity to temperature (24, 30, and 36°C) were evaluated in mummichog Fundulus heteroclitus across a range of body sizes spanning YOY to adult (35-68 mm standard length). Mummichogs exhibit isometry of body dimensions and areas of the dorsal and anal fins but negative allometry of the caudal fin area. These scaling relationships are consistent with observed decreases in fast-start angular velocities with increasing body size. Linear velocity, on the contrary, does not vary with size, and both large and small mummichogs are capable of traversing similar distances in a given amount of time. In addition, temperature influences fast-start performance in similar ways over the size range, though the magnitude of the effect varies with size for some performance measures. In general, fast-start performance increases with test temperature, but mummichogs acclimated to warmer temperatures exhibit lower performance at each test temperature. Altogether, our results suggest that mummichogs across the adult size range may suffer decreases in their predator-escape performance as increasing sea temperatures combine with short-term temperature fluctuations in the estuaries these fish occupy.

Position of Polyclithrum within Gyrodactylidae (Monogenoidea): incongruences between morphological and molecular phylogenies.

This study aimed to enhance our understanding in monogenoid evolution by using morphological and molecular data to determine kinship relationships between species and changes in morphological structures over time. We focused on variations in characteristics among the organisms of the family Gyrodactylidae, concentrating on the phylogenetic position of Polyclithrum with other genera in the family. We collected specimens of Polyclithrum from the striped mullet, Mugil cephalus and Swingleus, and Fundulotrema specimens from mummichog Fundulus heteroclitus in estuarine systems of South Carolina, United States. In addition, we analyzed them and other genera (including e.g., Mormyrogyrodactylus, Gyrodactyloides, and Macrogyrodactylus) using both morphological and molecular (18S rDNA) approaches. We performed phylogenetic trees based on Maximum Parsymony, Maximum Likelihood and Bayesian Inference, and constructed a character morphological matrix by Parsimony Reconstruction of Ancestral Character States method. Our results suggest a homoplastic origin with evolutionary convergences in characters, revealing that there is inconsistency between our data and previously published works based solely on morphological structures of the group. The homoplasy scenario found in Gyrodactylidae can be a result of the limited set of putative homologous morphological features. However, differences between the phylogenies based on morphology and those based on molecular data may arise from both databases. While morphology remains essential in understanding the evolution of this group, molecular data, otherwise, provide a less biased source of information for constructing phylogenetic hypotheses. Combining these data facilitates a better comprehension of the homologous status of morphological features and to understand Gyrodactylidae evolutionary history.

Effects of Frozen Storage on Fish Wet Weight, Percent Dry Weight, and Length Revisited

AbstractFrozen storage can affect the physical characteristics of biological samples, and the effects can vary based on the frozen storage method that is used. We compared four frozen storage treatments: (1) flash frozen in liquid nitrogen (LN2) and stored at −20°C, (2) flash frozen in LN2 and stored at −65°C, (3) frozen in a saline solution (0.9% NaCl) and stored at −20°C, and (4) glazed with deionized (DI) water and stored at −20°C, to investigate the effects of frozen storage on wet weight, percent dry weight, and length of Mummichogs Fundulus heteroclitus. Mummichog wet weights differed from Prestorage wet weights for all treatments. Postthaw wet weight increased from the Prestorage wet weight for Mummichogs that were frozen in a saline solution (3–5% for 4–12 g fish). Conversely, Postthaw wet weight decreased from Prestorage wet weight (1–4% for 4–12 g fish) for Mummichogs that were frozen with LN2 and stored at −20°C or −65°C and Mummichogs that were glazed with deionized water and stored at −20°C. Subsequently, percent dry weight was underestimated by 0.77% for the Mummichogs that were frozen in a saline solution and overestimated for those that were frozen with LN2 and stored at −20°C (0.94%) or −65°C (0.60%) and those that were glazed with deionized water and stored at −20°C (0.71%). Fish total length decreased 2–3% after the samples had been frozen, and they did not differ among the four treatments. When possible, fish that are stored frozen should be measured and weighed alive or immediately after being euthanized, and if this is not possible, we suggest glazing the fish with water and developing correction factors for water loss and shrinkage.

Linking Historical Changes in Salt‐Marsh Coverage to Lost Production of a Nektonic Bioindicator

AbstractDevelopment reduces the amount of secondary biological production in coastal estuaries. However, the magnitude of this reduction remains largely unknown. We are not aware of studies that have quantified lost secondary biological production in estuaries as a result of interdecadal coastal development of salt‐marsh habitats. Our objective was to demonstrate a technique that combined historical imagery, GIS, and secondary production estimates to quantify the magnitude of lost areal production arising from the development of tidal creeks. We estimated lost production of a dominant salt‐marsh fish MummichogFundulus heteroclitusin Spooners and Pelletier creeks, two second‐order tidal systems in coastal North Carolina. We georeferenced historical (1939) aerial imagery, digitized low‐tide and high‐tide features in historical and contemporary (2019) imagery, and compared the intertidal vegetated area of each creek between periods. The lost intertidal area was then multiplied by creek‐specific published rates of areal production of larval and juvenile age‐0 Mummichog in salt‐marsh cordgrassSpartina alterniflorahabitats. There was a loss of intertidal area and intertidal/subtidal vegetated edge of 72% and 54%, respectively, in Spooners Creek, and 47% and 4%, respectively, in Pelletier Creek. Losses of intertidal area over the last ~80 years translated into estimated annual losses of 44 and 8 kg of dry weight production (~695,000 and 186,500 individuals) for a single cohort in Spooners and Pelletier creeks, respectively. These estimates represent minimum losses, as some in‐stream development was already visible in the historic imagery and a single cohort’s production was used (not multiple cohorts). We encourage other researchers to use historic imagery to determine changes in aquatic habitats and link losses (or gains) in these habitats to the productivity metrics of important fishes.

Birds versus fish: Nest flooding introduces predator–prey interactions in Georgia's coastal marshes

We document the first recorded instance of a fish depredating a hatchling bird while in the nest. Some coastal marsh-nesting avian species, such as the Seaside Sparrow (Ammospiza maritima), experience tradeoffs between the threat of nest predation and nest flooding. Nesting too low may result in nest flooding during the twice-daily high tides and increasing nest height increases the risk of nest predation. However, not much is known about how nest height affects exposure to different predators. We observed a mummichog (Fundulus heteroclitus) enter a Seaside Sparrow nest during a nest flooding event and depredate a hatchling. This observation expands our understanding of the predator–prey relationships experienced by coastal marsh-nesting birds, and the potential detriments of intensifying sea level rise on their nesting success.

The occurrence, distribution and biology of invasive fish species in fresh and brackish water bodies of NE Morocco

Monitoring the presence and expansion of alien species and upgrading their biological and ecological knowledge seems crucial to mitigate their possible impact on native communities. Within inland superficial waters, alien fish represent an important threat to the biodiversity and studies on their impact on native communities have increased around the world in the last years. However, little is known about their occurrence, biology and influences in North Africa in general, and more specifically in Morocco. In the present work we aimed to: 1) investigate the presence of any native Aphanius species, especially the Mediterranean killifish Aphanius fasciatus recorded from the lower basin of the Moulouya River (NE Morocco); 2) monitor the presence and expansion of two invasive species, the eastern mosquitofish Gambusia holbrooki and the mummichog Fundulus heteroclitus; and 3) contribute to the understanding of the ecological and abiotic affinities that govern the distribution of these alien fishes in North Africa. To achieve these goals, several field sampling campaigns were carried out between 2014 and 2018 across eastern Morocco, comprising the administrative Oriental Region and the Moulouya River Basin and covering an area of 119,268 km2. No native Aphanius species were found. The eastern mosquitofish has invaded the freshwater hydrosystems of the northern part of Morocco, including the study area, while the mummichog is currently limited to the brackish and salty wetlands of Lower Moulouya. Our results show that the known ranges of these two alien species have expanded. Data published through GBIF (Doi:10.15470/2qed9o)

Fast-start escape performance across temperature and salinity gradients in mummichog Fundulus heteroclitus.

Fast-start predator-escape performance of mummichogs Fundulus heteroclitus was tested across field-informed variation in temperature (24, 30 and 36°C) and salinity (2, 12 and 32 ppt). Performance was similar across temperatures and salinities when fish were allowed to acclimate to these conditions. However, when mummichogs experienced acute temperature changes, performance exhibited thermal dependence in two contrasting ways. Fast-start turning rates and linear speeds varied directly with the temperature at which the manoeuvre was executed, but these aspects of performance varied inversely with acclimation temperature, with cool-acclimated fish exhibiting faster starts across test temperatures. Temperature effects were consistent across salinities. These results suggest that while mummichogs increase performance with acute temperature increases, long-term rises in sea temperature may cause these fish to become more susceptible to predation during abrupt cooling events, such as when storm events flood shallow water estuaries with cool rainwater.

Salinity affects growth but not thermal preference of adult mummichogs Fundulus heteroclitus.

The effects of an ecologically relevant range of salinities (2, 12, 22, 32) on thermal preferences and growth of adult mummichogs Fundulus heteroclitus were determined for fish from a southern Chesapeake Bay population. Salinity did not affect the mean temperature selected by F. heteroclitus in a thermal gradient, which was identified as 26.6°C based on observations of 240 individuals. Salinity and temperature had significant and interacting effects on growth rates of F. heteroclitus measured over 12 weeks. Growth rates were highest overall and remained high over a broader range of temperatures at moderate salinities (12 and 22), while high growth rates were shifted toward lower temperatures for fish grown at a salinity of 2 and higher temperatures at a salinity of 32. Significant reductions in growth relative to the optimal conditions (28.6°C, salinity of 22) were observed at the coolest (19.6°C) and warmest (33.6°C) temperature tested at all salinities, as well as temperatures ≥ 26.6°C at a salinity of 2, ≥ 28.6°C at a salinity of 12 and ≤ 26.6°C at a salinity of 32. Growth rates provide a long-term, organismal measure of performance and results of this study indicate that performance may be reduced under conditions that the highly euryhaline F. heteroclitus can otherwise easily tolerate. The combination of reduced salinity and increased temperature that is predicted for temperate estuaries as a result of climate change may have negative effects on growth of this ecologically important species.

Survival and Density of a Dominant Fish Species Across a Gradient of Urbanization in North Carolina Tidal Creeks

Development in the southeastern US coastal plain generates the need for a better understanding of how survival and abundance of estuarine nekton respond to urbanization. Apparent survival and density of the dominant Atlantic coast salt marsh fish, the mummichog Fundulus heteroclitus, were estimated in four North Carolina tidal creeks using a model simultaneously fitted to mark-resight and mark-recapture data. Rates of weekly loss (mortality plus emigration) were high (~ 10%). Sampling for tagged fish within and outside of study creeks showed high site fidelity to each creek, indicating that loss largely resulted from mortality rather than emigration. Estimated rates of apparent survival were lowest in the creek with the least instream- and watershed-level impacts. This creek has direct (non-culvert) access downstream to a larger waterbody, suggesting that enhanced access by predators and/or greater rates of permanent emigration may have contributed to lower apparent survival in this creek. There was a positive relation between minnow trap catch-per-unit-effort (CPUE) and density allowing the relationship between CPUE and habitat and urbanization to be examined in a total of six creeks. The largest CPUE estimates occurred early in each growing season and were associated with creeks possessing characteristics most representative of undisturbed salt marsh mosaics: high percentage of marsh coverage instream and downstream and high percentage of marsh edge. Given generally limited movement outside of creeks, differences in abundance among creeks likely result from different levels of recruitment that are related to salt marsh availability. Priority preservation of salt marsh habitats may be warranted by natural resource planners to maintain abundance levels of this trophically important species.

Survival, Tag Retention, and Growth of Spot and Mummichog following PIT Tag Implantation

AbstractWe conducted three laboratory studies to determine the effects of surgically implanted, passive integrated transponder (PIT) tags on survival, tag retention, and growth in two abundant estuarine fishes. The effects of the 12.5‐mm PIT tags were examined in Spot Leiostomus xanthurus, and the effects of the 12.5‐mm and 8.4‐mm tags were examined in Mummichog Fundulus heteroclitus. For each experiment, Spot and Mummichogs were divided into three size‐groups: small, medium, and large. Tagged Spot had lower survival rates than the untagged conspecifics with the exception of the larger Spot, where there was no difference in survival rates. Large Spot also had the highest tag retention (86%) and tagging “success” (i.e., 80% survived and retained their tag). There was no significant difference in the survival rate between the 12.5‐mm tagged and untagged Mummichogs; there was no significant effect of Mummichog size on survival, tag retention, or success; and success for all 12.5‐mm tagged Mummichogs was 87%. Survival estimates were 90%, 95%, and 100% for the small, medium, and large 8.4‐mm tagged Mummichogs; and tag retention was 100% for the survivors. Within the medium and large sized Spot and Mummichogs (for both 8.4‐mm and 12.5‐mm tags), there was no effect of PIT tag presence on growth (length or weight). Spot should be >68 mm TL to obtain a tag success of >90% using 12.5‐mm PIT tags. Tagging was successful for Mummichogs in the smallest sized groups examined but there was also an indication of lower growth rates for Mummichogs <50 mm marked with 12.5‐mm PIT tags. Mummichogs should thereby be >50 mm when initially tagged with 12.5‐mm PIT tags and more than ~36 mm TL when tagged with 8.4‐mm PIT tags. PIT tags can be used to successfully mark relatively small Spot and Mummichogs, potentially allowing for robust estimates of their demographic rates.Received April 2, 2015; accepted December 16, 2015 Published online May 31, 2016

A fish mortality episode reveals the expansion of invasive mummichog Fundulus heteroclitus (L., 1766) in southern Spain

A fish mortality episode reveals the expansion of invasive mummichog Fundulus heteroclitus (L., 1766) in southern Spain

Comparison of Bottomless Lift Nets and Breder Traps for Sampling Salt‐Marsh Nekton

AbstractVegetated salt‐marsh surfaces provide refuge, forage, and spawning habitat for estuarine nekton, yet are threatened by accelerating rates of sea‐level rise in southern New England and elsewhere. Nekton responses to ongoing marsh surface changes need to be evaluated with effective and quantitative nekton sampling gear. The goal of this study was to evaluate the effectiveness of different gear for monitoring nekton in emergent salt‐marsh vegetation by comparing nekton parameters between Breder traps and bottomless lift nets and between Breder traps made from different materials. Breder traps collected a significantly different nekton community, fewer species, and larger‐sized Mummichogs Fundulus heteroclitus than did lift nets. Nekton community composition, richness, and the size of green crabs Carcinus maenas also differed significantly between Breder traps constructed from acrylic and wire mesh. These results show that it is not appropriate to directly compare nekton data between Breder traps and lift nets, nor between Breder traps made from different materials. Our lift‐net data correspond well to other data collected with enclosure traps in southern New England. We recommend lift nets or similar enclosure traps for sampling nekton in emergent marsh vegetation and caution against using Breder traps in monitoring and assessment programs.

The effects of salinity on swimming performance of two estuarine fishes, Fundulus heteroclitus and Fundulus majalis.

Prolonged and high-speed swimming performance measurements were used to explore the swimming abilities of two species of estuarine fishes, the mummichog Fundulus heteroclitus and the striped killifish Fundulus majalis, under different salinities. Critical swimming performance was significantly higher for F. majalis in high salinity than in low salinity, but no difference was observed in brief constant acceleration swimming trials in this species; however, the swimming performance of F. heteroclitus was not significantly affected by salinity changes, indicating that this species is well adapted to regular estuarine salinity oscillations. Fundulus majalis displayed higher swimming speeds than F. heteroclitus in both high and low salinities, and while this cannot be explained by their respective salinity preferences, the specific habitat preferences of F. majalis for sandy subtidal habitats and F. heteroclitus for vegetated marshes could explain the better swimming performance of F. majalis.

The effects of the parasite Probopyrus pandalicola (Packard, 1879) (Isopoda, Bopyridae) on the behavior, transparent camouflage, and predators of Palaemonetes pugio Holthuis, 1949 (Decapoda, Palaemonidae)

The bopyrid isopod Probopyrus pandalicola (Packard, 1879) is a large, noticeable, hematophagous ectoparasite of palaemonid shrimps, including the daggerblade grass shrimp Palaemonetes pugio Holthuis, 1949. Bopyrids affect grass shrimp physiology and may also affect predator-prey dynamics. The purpose of this study was to determine whether the isopod affected the behavior and/or camouflage of grass shrimp, thereby altering the predation preferences of the mummichog Fundulus heteroclitus (Linnaeus, 1766). To determine whether the isopod affected predator preference through behavioral and/or camouflage alterations, paired combinations of unparasitized, parasitized, and marked shrimp were presented to mummichogs. One branchiostegite of some of the unparasitized shrimp was marked with black paint to mimic the bopyrid parasite. Mummichog predation preference and shrimp behavior immediately prior to predation events were recorded. All shrimp behavior was classified as motionless, walking, swimming, or backward thrusting. Immediately prior to predation, parasitized shrimp swam more () and backward thrusted less () than unparasitized shrimp. Mummichogs exhibited a preference for the more active shrimp (80.7% of shrimp; ), and also for the less camouflaged (parasitized or marked) shrimp (81.5% of shrimp; ) if there was no difference in shrimp behavior. Parasitized shrimp were preferentially consumed (51/85 shrimp) when paired with unparasitized shrimp (), but not with marked shrimp (). A 30-min activity budget was created for each type of shrimp both in the presence and absence of predators; neither the parasite nor marking affected their behavior over 30 min (). The major finding of this study was that P. pandalicola affected the predation preferences of F. heteroclitus by altering the behavior and/or camouflage of the grass shrimp. Parasitization alters predator-prey dynamics by decreasing the camouflage and the frequency of backward-thrusting behavior by the host when it is threatened by predation, which thereby decreases the ability of shrimp to escape from predators.

Performance of Two Egg Collector Designs for Use with Mummichogs

AbstractThe Mummichog Fundulus heteroclitus is a popular marine baitfish in the species’ natural range along the east coast of North America from Florida to the Gulf of St. Lawrence. Interest in commercial culture of Mummichogs has grown over the last two decades, but little research has been conducted to examine species‐specific culture techniques; thus, Mummichog culture has not advanced. Our objectives were to evaluate the performance of two egg collectors designed to mimic the structures of natural substrates and to maximize labor efficiency. A tray‐style collector (TSC) and a disk‐style collector (DSC) were both placed in each of six 5,000‐L tanks stocked with approximately 700 adult Mummichogs of both sexes. The numbers of eggs collected, fertilized eggs, and viable larvae that hatched as well as the time required to rinse collectors during each biweekly collection were compared between the two designs. Over the 8‐week study, there was no significant difference between designs in terms of the number of eggs collected or the total rinse time. However, the percentage of unfertilized eggs collected was twice as high for TSCs (mean ± SD = 8.53 ± 0.59%) than for DSCs (4.42 ± 0.36%). Additionally, larval yield was significantly higher for DSCs (79.10 ± 12.93%) than for TSCs (72.63 ± 13.95%). Based on these results, we conclude that both designs are efficient at collecting Mummichog eggs and that the DSC is the more advantageous design for maximizing fertilization rate and larval yield.

Estimating movement and survival rates of a small saltwater fish using autonomous antenna receiver arrays and passive integrated transponder tags

We evaluated the performance of small (12.5 mm long) passive integrated transpon- der (PIT) tags and custom detection antennas for obtaining fine-scale movement and demographic data of mummichog Fundulus heteroclitus in a salt marsh creek. Apparent survival and detection probability were estimated using a Cormack Jolly Seber (CJS) model fitted to detection data col- lected by an array of 3 vertical antennas from November 2010 to March 2011 and by a single hor- izontal antenna from April to August 2011. Movement of mummichogs was monitored during the period when the array of vertical antennas was used. Antenna performance was examined in situ using tags placed in wooden dowels (drones) and in live mummichogs. Of the 44 tagged fish, 42 were resighted over the 9 mo monitoring period. The in situ detection probabilities of the drone and live mummichogs were high (~80�100%) when the ambient water depth was less than ~0.8 m. Upstream and downstream movement of mummichogs was related to hourly water depth and direction of tidal current in a way that maximized time periods over which mummichogs uti- lized the intertidal vegetated marsh. Apparent survival was lower during periods of colder water temperatures in December 2010 and early January 2011 (median estimate of daily apparent sur- vival = 0.979) than during other periods of the study (median estimate of daily apparent survival = 0.992). During late fall and winter, temperature had a positive effect on the CJS detection proba- bility of a tagged mummichog, likely due to greater fish activity over warmer periods. During the spring and summer, this pattern reversed possibly due to mummichogs having reduced activity during the hottest periods. This study demonstrates the utility of PIT tags and continuously oper- ating autonomous detection systems for tracking fish at fine temporal scales, and improving esti- mates of demographic parameters in salt marsh creeks that are difficult or impractical to sample with active fishing gear.

Food web structure within an estuary of the southern Gulf of St. Lawrence undergoing eutrophication

This study compared food web structure in eutrophied Ulva lactuca-dominated areas within an estuary in the Southern Gulf of St. Lawrence, with Zostera marina beds within the same estuary. The estuarine food web consisted only of primary producers, mesograzers, and secondary grazers, with the absence of piscivorous top predators. It was hypothesized that the altered plant habitat would lead to structural changes in the food web and the dominance of benthic carbon. Stomach contents from mummichog (Fundulus heteroclitus), fourspine stickleback (Apeltes quadracus), and American eel (Anguilla rostrata) showed that only mummichog had significant differences in prey items between the different habitats. Stable isotopes showed that there were no significant differences in the food web structure and individual species’ 13C values. A 13C spike in particulate organic matter during the onset of anoxia in July, presumably due to bacterial blooms, indicated the complete dominance of benthic carbon the pelagic food web during this month. Thus, blooms of heterotrophs during anoxic events may have the greatest influence on nutrient cycling in estuaries undergoing eutrophication.

Mummichog Fundulus heteroclitus responses to long-term, whole-ecosystem nutrient enrichment

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 492:211-222 (2013) - DOI: https://doi.org/10.3354/meps10495 Mummichog Fundulus heteroclitus responses to long-term, whole-ecosystem nutrient enrichment Konner C. Lockfield1, John W. Fleeger1,*, Linda A. Deegan2 1Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA 2The Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA *Corresponding author. Email: zoflee@lsu.edu ABSTRACT: The effects of eutrophication on coastal plants and sessile animals are becoming well known, but responses of mobile species are less well studied. Here, we link variation in abundance, biomass, body size, growth rate, and resource utilization in mummichogs Fundulus heteroclitus >40 mm in length to experimental nutrient enrichment in Plum Island Sound, Massachusetts, USA. To mimic cultural eutrophication, dissolved fertilizer was released into replicate saltmarsh creeks on each rising tide throughout entire growing seasons. In the summer of the sixth year of enrichment, we released coded-wire tagged mummichogs into nutrient-enriched (n = 3733 fish) and reference (n = 3894 fish) creeks and recaptured them over the next 2 mo. We found increased abundance (by 37%), biomass (58%), body size (8%), and herbivory (115%, measured as photosynthetic gut pigment content) in nutrient-enriched creeks, although body condition was unaffected. However, individual growth rates were 43% lower in nutrient-enriched creeks. Nutrient enrichment stimulated primary production, causing a bottom-up enrichment of the food web which fostered increased biomass and body size. However, the reduction in growth rate indicates an adverse consequence of long-term nutrient enrichment. This negative effect occurred in the absence of increased hypoxia in these highly tidally (4 m amplitude) flushed study creeks. The mummichog is an important predator/grazer in salt marshes, and nutrient-induced alterations in biomass or resource utilization will directly or indirectly affect lower trophic levels, including benthic algae, thereby impacting the ecosystem-wide response to eutrophication. KEY WORDS: Fundulus heteroclitus · Mark and recapture · Eutrophication · Decimal coded-wire tags · Growth rate · Salt marsh Full text in pdf format PreviousNextCite this article as: Lockfield KC, Fleeger JW, Deegan LA (2013) Mummichog Fundulus heteroclitus responses to long-term, whole-ecosystem nutrient enrichment. Mar Ecol Prog Ser 492:211-222. https://doi.org/10.3354/meps10495 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 492. Online publication date: October 31, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Toxicity of Degradation Products of the Antifouling Biocide Pyridine Triphenylborane to Marine Organisms

We evaluated the acute toxicities of the main degradation products of pyridine triphenylborane (PTPB), namely, diphenylborane hydroxide (DPB), phenylborane dihydroxide (MPB), phenol, and biphenyl, to the alga Skeletonema costatum, the crustacean Tigriopus japonicus, and two teleosts, the red sea bream Pagrus major and the mummichog Fundulus heteroclitus. DPB was the most toxic of the degradation products to all four organisms. The acute toxicity values of DPB for S. costatum, T. japonicus, red sea bream, and mummichog were 55, 70, 100, and 200-310μg/L, respectively. The degradation products were less toxic than PTPB to S. costatum and T. japonicus; however, the toxicities of DPB and PTPB to the fish species were similar. We also examined changes in the inhibition of growth rate of S. costatum as well as the percentage of immobilization of T. japonicus as end points of toxicity of PTPB after irradiation of PTPB with 432±45W/m(2) of 290-700nm wavelength light. After 7days of irradiation with this light, the concentration of PTPB in the test solutions decreased markedly. A decrease in toxic effects closely coincided with the decrease in the concentration of PTPB caused by the irradiation. PTPB probably accounted for most of the toxicity in the irradiation test solutions. Because the concentrations of PTPB that were acutely toxic to S. costatum and T. japonicus were <10% of the corresponding concentrations of its degradation products, PTPB probably accounted for most of the toxicity in the irradiation test solutions.

Evaluating cumulative effects of anthropogenic inputs in Prince Edward Island estuaries using the mummichog (Fundulus heteroclitus)

Estuarine eutrophication as a result of agricultural land use, including the use of chemical fertilizers, is increasing worldwide. Prince Edward Island (PEI), Canada has very high agricultural intensity by international standards with approximately 44% of the land area under production, and some watersheds in excess of 75% agricultural land-use. The type of agriculture is also intensive with primarily row crops that have high chemical fertilizer and pesticide usage. In light of these stressors, the hypothesis of this study was that mummichog (Fundulus heteroclitus) population parameters would change with point and nonpoint source pollution, and that multivariate statistics could be used to draw associations with specific stressors. Fish were sampled on a monthly basis from May through August at 7 estuaries spanning a range of land use, nutrient, and contaminant loadings. A suite of environmental variables were simplified into 3 principal components: PC1 representing agricultural land use, N loading, and plant habitat, PC2 being dominated by sediment sand and silt distribution, and PC3 largely reflecting P loading and sediment organic matter. There were significant differences in abundance of both adult and young-of-the-year mummichog, and these changes associated most strongly with PC1, the largely N-driven agricultural influences. In contrast, somatic variables such as liver and gonad size did not show strong association with the environmental quality principal component scores. The sand and silt PC2 appeared to have the opposite association with the biological data, with siltier environments correlating to older, larger, less dense populations of mummichog. Although pesticide residues were detected in estuarine sediment, there was no clear relationship between these and watershed agricultural intensity or biochemical indicators. There was, however, a strong relationship between agricultural environmental variables (PC1) and in vitro steroid production that is suggestive of a potential chemical effect. Eutrophication appeared to be a primary stressor affecting mummichog populations, as nutrient enrichment was associated with changes in habitat variables and these in turn were associated with high mummichog density. Thus, mummichog population demographics appear to have use as an indicator of adverse or worsening conditions in estuaries. We concluded that, based on the subset of environmental factors evaluated, the nonpoint-source inputs of sediments and nutrients exerted the greatest influence on mummichog populations in PEI estuaries.