Saint John River Estuary Research Articles

In-situ and real-time nano/microplastic coatings and dynamics in water using nano-DIHM: A novel capability for the plastic life cycle research

A novel nano-digital inline holographic microscope (nano-DIHM) was used to advance in-situ and real-time nano/microplastic physicochemical research, such as particle coatings and dynamic processes in water. Nano-DIHM data provided evidence of distinct coating patterns on nano/microplastic particles by oleic acid, magnetite, and phytoplankton, representing organic, inorganic, and biological coatings widely present in the natural surroundings. A high-resolution scanning transmission electron microscopy confirmed nano-DIHM data, demonstrating its nano/microplastic research capabilities. The sedimentation of two plastic size categories was examined: (a) ∼10 to 700 µm, and (b) ∼ 1 to 5 mm. Particle size was the primary factor affecting the sedimentation for studied (a) microplastics and (b) pellets. Two types of silicone rubbers exhibited different sedimentation processes. We also demonstrated that inorganic ions in seawater and oleic acid organic coatings altered the sedimentation velocity of studied plastics by 9 – 13% and 5 – 9%, respectively. Semi-empirical probability functions were developed and incorporated into a numerical model (CaMPSim-3D) to simulate the transport of studied microplastics and pellets in the Saint John River estuary. Water dynamics was the driving force of plastic transport, yet the accumulation of plastics was selectively dependant on particle physicochemical properties such as size and density by ∼ 7%. The usage of nano-DIHM for targeted identification of nano/microplastic hotspots and aquatic plastic wastes remediation were discussed.

A numerical framework for modeling fate and transport of microplastics in inland and coastal waters.

Proliferation of microplastics in rivers, lakes, estuaries, coastal waters and oceans is a major global challenge and threat to the environment, livelihoods and human health. Reliable predictive tools can play an essential role in developing an improved understanding of microplastics behaviour, exposure and risk in water bodies, and facilitate identification of sources and accumulation hot spots, thereby enabling informed decision-making for targeted prevention and clean-up activities. This study presents a new numerical framework (CaMPSim-3D) for predicting microplastics fate and transport in different aquatic settings, which consists of a Lagrangian, three-dimensional (3D) particle-tracking model (PTM) coupled with an Eulerian-based hydrodynamic modeling system (TELEMAC). The 3D PTM has several innovative features that enable accurate simulation and efficient coupling with TELEMAC, which utilizes an unstructured computational mesh. The PTM is capable of considering spatio-temporally varying diffusivity, and uses an innovative algorithm to locate particles within the Eulerian mesh. Model accuracy associated with different advection schemes was verified by comparing numerical predictions to known analytical solutions for several test cases. The implications of choosing different advection schemes for modeling microplastics transport was then investigated by applying the PTM to simulate particle transport in the lower Saint John River Estuary in eastern Canada. The sensitivity of the PTM predictions to the advection scheme was investigated using six numerical schemes with different levels of complexity. Predicted particle distributions and residence times based on the fourth-order Runge-Kutta (RK4) scheme differed significantly (residence times by up to 100%) from those computed using the traditional first-order (Euler) method. The Third Order Total Variation Diminishing (TVD3) Runge-Kutta method was found to be optimal, providing the closest results to RK4 with approximately 27% lower computational cost.

Mercury bioaccumulation in aquatic biota along a salinity gradient in the Saint John River estuary

Although estuaries are critical habitats for many aquatic species, the spatial trends of toxic methylmercury (MeHg) in biota from fresh to marine waters are poorly understood. Our objective was to determine if MeHg concentrations in biota changed along a salinity gradient in an estuary. Fourspine Stickleback (Apeltes quadracus), invertebrates (snails, amphipods, and chironomids), sediments, and water were collected from ten sites along the Saint John River estuary, New Brunswick, Canada in 2015 and 2016, with salinities ranging from 0.06 to 6.96. Total mercury (proxy for MeHg) was measured in whole fish and MeHg was measured in a subset of fish, pooled invertebrates, sediments, and water. Stable sulfur (δ34S), carbon (δ13C), and nitrogen (δ15N) isotope values were measured to assess energy sources (S, C) and relative trophic level (N). There were increases in biotic δ13C and δ34S from fresh to more saline sites and these measures were correlated with salinity. Though aqueous MeHg was higher at the freshwater than more saline sites, only chironomid MeHg increased significantly with salinity. In the Saint John River estuary, there was little evidence that MeHg and its associated risks increased along a salinity gradient.

Population Characteristics of Adult Atlantic Sturgeon Captured by the Commercial Fishery in the Saint John River Estuary, New Brunswick

AbstractThe commercial fishery for Atlantic Sturgeon Acipenser oxyrinchus in the Saint John River, New Brunswick, began in 1880. The early fishery was unregulated, and the adult stock was depleted by 1886 after landings of 712 metric tons. After a 10‐year closure the fishery was reopened in 1897 with management regulations, and landings varied from 6 to 20 metric tons/year until 2010. In 2011 an annual quota of 350 adults was established and landings are now stable at 11.3 ± 1.7 (mean ± SD) metric tons/year. Since 2009, fishers have collected biological statistics from adults taken in the fishery and 14–60% of captured individuals have been marked and released each year. During 2009–2015, annual mean values of total length and dressed weight of landed adults were stable, the male : female sex ratio was 1.2:1.0, and mean age of males and females was 27.2 and 34.0 years, respectively. Estimates of instantaneous total mortality ranged from 0.08 to 0.11, and mean annual survival was 90.9%. Of 1,396 marked adults released, 147 were recaptured in the estuary in subsequent years. Tag returns indicated that the modal spawning periodicity of males was 2 years and that of females was 4 years. Valid, modified Schnabel and Jolly–Seber mean annual population estimates for 2013–2015 were 18,179 and 20,798 adults, respectively. The quota in relation to these estimated adult populations represented annual exploitation rates of 1.9% and 1.7%, which are below F50 and would maintain present stock size. The virgin adult population was determined using 1880–1886 total landings and a mean weight range for adults of 50–30 kg. Estimated range of the 1880 virgin population size was 14,240–23,733 adults. These data suggest that the fishery is sustainable at its current annual yield and that the population is near the carrying capacity of the Saint John River.Received July 12, 2016; accepted November 17, 2016 Published online February 21, 2017

Diapycnal mixing and internal waves in the Saint John River Estuary, New Brunswick, Canada with a discussion relative to the Baltic Sea

Results of a detailed oceanographic survey in the Saint John River Estuary, New Brunswick, Canada are presented. It is shown that interfacial mixing occurs in this highly stratified basin at discrete locations at a particular phase of the tide leading to a plunging pycnocline at most of these locations. This process is possibly initiated by different kind of internal waves or/and the changing velocity direction on interaction with the irregular bathymetry. Analysis of the flow structure in terms of the critical Richardson number, based on previous studies in the Baltic Sea, shows that these mechanisms and similar phenomena evidently occur at strong density interfaces in the Baltic Sea area where internal waves are less regular but still essentially contribute to interfacial mixing.

Life History of the Marine Isopod <em>Cyathura polita</em> in the Saint John River Estuary, New Brunswick: a Species at the Northern Extent of its Range

The marine isopod, Cyathura polita, inhabits estuaries on the east coast of North America from the Gulf of Mexico to the Bay of Fundy, Canada. We studied C. polita in the Saint John estuary to test for potential differences in life history that might occur because of the northern location of the population. In the Saint John, based on our interpretation from a six-month sampling program (May-October), the population exhibits a three-year life cycle, one year longer than more southern populations, and stretching over four summers. Our study supported the occurrence of protogynic hermaphroditism. After two summers as juveniles, individuals matured as females during their third summer, then displayed sex reversal by becoming males that fall, and finally reproducing as males in their fourth summer of life before death. Mean length of C. polita from the Saint John was greater than individuals from more southern populations (females, 13.8 ± 2.14 mm; males, 16.3 ± 2.41 mm). Annual brood release occurred in late July-early August. Mean fecundity of females was 53.2 ± 18.9 embryos per brood, which was greater than found in southern populations. Cyathura polita is rare in Canada and is known only from the Saint John and along the northern shore of the Bay of Fundy to the border of the United States.

Influence of predation on shell morphology of Buccinum undatum L. on Atlantic coast of Canada

Striking differences were found in the morphology of the boreal neogastropod Buccinum undatum L. among populations in the northern Gulf of Saint Lawrence, in Maces Bay in the Bay of Fundy, and in Kennebecasis Bay in the Saint John River estuary, eastern Canada. The Kennebecasis Bay whelks had the thinnest shells and in the laboratory were rapidly consumed by lobster with no evidence of size selection, whereas the Maces Bay whelks had the most robust shells and were slowly attacked by lobster with smaller individuals being selected first. Similar results were obtained for crabs, except that intermediate-sized Maces Bay whelks were selected. We postulate that the increased shell thickness and elongated apertures of the Maces Bay whelks are adaptations to lobster and crab predation at this site, whereas the thinner shells of Kennebecasis Bay and Gulf whelks reflects decreased crustacean predation. The smaller rounder apertures of the Gulf whelks, compared with the Maces Bay whelks, could be an adaptation to increased seastar predation, but the relative aperture size was even smaller in Kennebecasis Bay where seastars were absent. The very low incidence of the violent escape response in Maces Bay whelks and its absence in Kennebecasis Bay whelks is surprising and may indicate that seastars have little impact on these whelk populations.

Transmission and development of Capillospirura pseudoargumentosa (Appy and Dadswell, 1978) (Nematoda: Cystidicolidae)

The cystidicolid nematode, Capillospirura pseudoargumentosa (Appy and Dadswell, 1978) (Habronematoidea) moulted twice and developed to the infective third stage in Gammarus tigrinus and G. fasciatus (Amphipoda) but not in isopods, decapods, mysids or other amphipods. At 10–14 °C development to the third stage in G. tigrinus took between 28 and 40 days and at 21–25 °C, it took between 10 and 15 days. Infective larvae fed to shortnose sturgeon, Acipenser brevirostrum, moulted from the third to the fourth stage within 15 days. Moulting third- and fourth-stage larvae were found in naturally infected sturgeon collected in the Saint John River estuary, New Brunswick. The developmental morphology of C. pseudoargumentosa is compared with that of other cystidicolid nematodes.

Occurrence and Biology of Cyathura Polita (Stimpson) (Isopoda, Anthuridae) in Canada

[A large reproducing population of Cyathura polita occurs in the Saint John River estuary, New Brunswick, Canada. This is the first record from Canada and represents a 180 km northeastward extension of the known range for this species. A large portion of the Cyathura population occupies deep (20 m), mesohaline (0.1-20‰) water on bottoms of moderate silt-clay content. The population exhibits protogynic hermaphroditism, a phenomenon common to cyathurans. This occurrence, disjunct from the main center of Cyathura polita distribution to the south, may be a result of an earlier widespread distribution during the Hypsithermal Period with a subsequent fracturing of the range during recent cooler climatic conditions., A large reproducing population of Cyathura polita occurs in the Saint John River estuary, New Brunswick, Canada. This is the first record from Canada and represents a 180 km northeastward extension of the known range for this species. A large portion of the Cyathura population occupies deep (20 m), mesohaline (0.1-20‰) water on bottoms of moderate silt-clay content. The population exhibits protogynic hermaphroditism, a phenomenon common to cyathurans. This occurrence, disjunct from the main center of Cyathura polita distribution to the south, may be a result of an earlier widespread distribution during the Hypsithermal Period with a subsequent fracturing of the range during recent cooler climatic conditions.]

Parasites of Acipenser brevirostrum LeSueur and Acipenser oxyrhynchus Mitchill (Osteichthyes: Acipenseridae) in the Saint John River Estuary, N.B., with a description of Caballeronema pseudoargumentosus sp.n. (Nematoda: Spirurida)

Eleven species of helminth and arthropod parasites are reported from Acipenser brevirostrum and Acipenser oxyrhynchus in the Saint John River estuary, N.B., Canada. Diclybothrium armatum, Spirorchis sp., Fessesentis friedi, and Argulus alosa are new records from A. brevirostrum. Derogenes varicus, Truttaedacnitis sphaerocephala, Echinorhynchus gadi, and Dichelesthium oblongum are new records from A. oxyrhynchus. Truttaedacnitis sphaerocephala and D. oblongum are new locality records for North America. Caballeronema pseudtiargumentosus sp.n. is described from A. brevirostrum and differs from the similar spirurid Ascarophis argumentosus in length of spicules (110–138 μm and 492–598 μm versus 81–86 μm and 320–340 m), egg length (38–44 μm versus 29–35 μm), and number of egg filaments (4–10 versus 2). Details of the oral structure of C. pseudoargumentosus are described and its relationship to Ascarophis and Capillospirura discussed. Parasite fauna of adult A. oxyrhynchus, juvenile A. oxyrhynchus, and A. brevirostrum are distinct and reflect differing life histories and ecologies of the hosts.

An Oceanographical and Biological Reconnaissance of Kennebecasis Bay and the Saint John River Estuary

A preliminary survey of the oceanographic features of Kennebecasis Bay and the Saint John estuarial system was carried out in 1957–58 as part of the International Passamaquoddy Fisheries Board Program.Kennebecasis Bay and Long Reach on the Saint John River are two-layer systems with a brackish surface layer overlying a deep saline layer. Two sills separate and restrict exchange of deep water in Kennebecasis Bay from that of the Bay of Fundy. The initial step in the formation of deep water of Kennebecasis Bay occurs in the gorge area between the two sills where saline water from the Bay of Fundy mixes vigorously with fresh water of the Saint John River. During periods of low river runoff combined with spring tides a portion of the mixed water penetrates inward over the sill at the entrance to Kennebecasis Bay.It is concluded that Kennebecasis Bay represents more extreme conditions than those predicted for Passamaquoddy Bay if power dams are constructed.