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The Damming of the Petitcodiac River: Species, Populations, and Habitats Lost
Abstract
Construction of the Petitcodiac River Causeway in 1968 converted 21 km of macrotidal (tidal amplitude > 8 m) brackish-water estuary into a shallow impoundment. The ecological value of the freshwater impoundment was low, when judged by criteria of temporal stability, uniqueness, conservation of native species, and level of disturbance. By interfering with migrations, the causeway dam eliminated or greatly reduced the populations of most diadromous fishes, including a large population of the now-endangered Inner Bay of Fundy stock of Atlantic salmon (Salmo salar). Loss of the host fish for the parasitic glochidial stage resulted in extirpation of the dwarf wedgemussel (Alasmidonta heterodon) from Canada. Benthic and planktonic communities of the impoundment were depauperate, and typical of a disturbed ecosystem. Most species were of marine/estuarine origin, or belong to freshwater groups with rapid dispersal. Illegally introduced warm-water fishes flourished in the impoundment, presumably replacing the native species.
... In 1968, a causeway was built on the Petitcodiac River between Moncton and Riverview, New Brunswick, Canada. Constructed of rock-fill, this causeway incorporated five spillway gates, as well as a fishway (Wells 1999;Locke et al. 2003). It offered flood protection to farmland, a second transportation link between Moncton and Riverview, and created a freshwater headpond (Wells 1999). ...
... It offered flood protection to farmland, a second transportation link between Moncton and Riverview, and created a freshwater headpond (Wells 1999). The fishway was ineffective, and the causeway was ultimately responsible for the collapse of a genetically unique population of Atlantic Salmon (Salmo salar), and extirpation of American Shad (Alosa sapidissima) and Dwarf Wedgemussel (Alasmidonta heterodon) (Wells 1999;Locke et al. 2003). The causeway also resulted in increased erosion along the banks of the headpond, dampening of natural tidal cycles, decreased river flow velocity, and low levels of heavy-metal and fecal coliform contamination (Bray et al. 1982;Wells 1999;Locke et al. 2003;van Proosdij et al. 2009). ...
... The fishway was ineffective, and the causeway was ultimately responsible for the collapse of a genetically unique population of Atlantic Salmon (Salmo salar), and extirpation of American Shad (Alosa sapidissima) and Dwarf Wedgemussel (Alasmidonta heterodon) (Wells 1999;Locke et al. 2003). The causeway also resulted in increased erosion along the banks of the headpond, dampening of natural tidal cycles, decreased river flow velocity, and low levels of heavy-metal and fecal coliform contamination (Bray et al. 1982;Wells 1999;Locke et al. 2003;van Proosdij et al. 2009). ...
The spillway gates of the Petitcodiac Causeway, a hydraulic structure ~35 km upstream of the mouth of the Petitcodiac River in New Brunswick, Canada, were permanently opened in April 2010. The short-term effect opening the spillway gates had on downstream intertidal mudflats of the upper Bay of Fundy was investigated. Specifically, a multivariate before-after-control-impact design was used to determine if opening the spillway gates affected the invertebrate community (crustaceans, polychaetes, and molluscs), abiotic sediment conditions (sediment water content, mean particle size, penetrability, and depth of the apparent redox potential discontinuity), or resource availability (sediment chlorophyll a concentration and organic matter content) of five intertidal mudflats (two impacted sites, three reference sites) spanning Chignecto Bay, the northern arm of the upper Bay of Fundy, up to 5 months post-opening. No biologically or statistically meaningful differences were detected between impacted and reference sites for any of the measured variables. This suggests that opening the causeway did not have a quantifiable impact on these intertidal mudflats, at least within half a year of the opening. This is likely a result of the macrotidal nature of the Bay of Fundy that overwhelmed any immediate changes to hydrodynamics that occurred after the opening of the causeway gates.
... However, other characteristics may complicate distribution modelling (sensitivity to contaminants - Wang et al., 2007;Blakeslee et al., 2013;Wang et al., 2013; dependence on fish hosts - Zale and Neves, 1982;Michaelson and Neves, 1995). For example, suitable physical habitats may be present, but toxicity or the availability of hosts may be constraining distributions (Bogan, 1993;Locke et al., 2003;Angelo et al., 2007;Schwalb et al., 2013). Thus a species' current distribution may be a function of numerous factors. ...
... The federally endangered dwarf wedgemussel (Alasmidonta heterodon Lea, 1830) typifies this situation as it is endemic to Atlantic Slope drainages and populations are declining owing to stream impoundments, channel alteration, pollution, and likely other unknown factors (US Fish andWildlife Service, 1993, 2007;Locke et al., 2003). Locating additional populations of the species is constrained by the effort required to conduct snorkel surveys of all streams within its range, but predictive modelling may better focus the search extent. ...
• Species distribution modelling can be useful for the conservation of rare and endangered species. Freshwater mussel declines have thinned species ranges producing spatially fragmented distributions across large areas. Spatial fragmentation in combination with a complex life history and heterogeneous environment makes predictive modelling difficult.
• A machine learning approach (maximum entropy) was used to model occurrences and suitable habitat for the federally endangered dwarf wedgemussel, Alasmidonta heterodon, in Maryland's Coastal Plain catchments. Landscape‐scale predictors (e.g. land cover, land use, soil characteristics, geology, flow characteristics, and climate) were used to predict the suitability of individual stream segments for A. heterodon.
• The best model contained variables at three scales: minimum elevation (segment scale), percentage Tertiary deposits, low intensity development, and woody wetlands (sub‐catchment), and percentage low intensity development, pasture/hay agriculture, and average depth to the water table (catchment). Despite a very small sample size owing to the rarity of A. heterodon, cross‐validated prediction accuracy was 91%.
• Most predicted suitable segments occur in catchments not known to contain A. heterodon, which provides opportunities for new discoveries or population restoration. These model predictions can guide surveys toward the streams with the best chance of containing the species or, alternatively, away from those streams with little chance of containing A. heterodon.
• Developed reaches had low predicted suitability for A. heterodon in the Coastal Plain. Urban and exurban sprawl continues to modify stream ecosystems in the region, underscoring the need to preserve existing populations and to discover and protect new populations.
Copyright © 2016 John Wiley & Sons, Ltd.
... Widespread declines in species ranges have been attributed to changes in chemical or physical habitats and to dams or other structures that inhibit upstream migration of fish hosts (Smith, 1985;Bogan, 1993;Locke et al., 2003;Bogan, 2008). The sedentary nature of adult mussels makes them particularly vulnerable to local habitat changes, including increases in bed mobility, water pollution, deposition of fine sediment, and other habitat alterations that are often associated with urbanization, agriculture, logging, and other land-use changes (McRae et al., 2004;Gangloff & Feminella, 2007;Randhir & Hawes, 2009). ...
... We sought to identify physical and chemical habitat characteristics that constrain the distribution of the federally endangered dwarf wedgemussel (Alasmidonta heterodon Lea, 1830) in Flat Brook, a tributary of the upper Delaware River. The species is in decline due to a suite of human activities (e.g., impoundments, pollution, channel alteration, and siltation; U.S. Fish and Wildlife Service, 1993;Locke et al., 2003;U.S. Fish and Wildlife Service, 2007) that affect habitat and dispersal. Populations of A. heterodon generally occur in distinct, widely separated, low density patches in linear, unbranched sections of stream (Strayer et al., 1996). ...
Development of effective conservation and restoration strategies for freshwater pearly mussels requires identification of environmental constraints on the distributions of individual mussel species. We examined whether the spatial distribution of the endangered Alasmidonta heterodon in Flat Brook, a tributary of the upper Delaware River, was constrained by water chemistry (i.e., calcium availability), bed mobility, or both. Alasmidonta heterodon populations were bracketed between upstream reaches that were under-saturated with respect to aragonite and downstream reaches that were saturated for aragonite during summer baseflow but had steep channels with high bed mobility. Variability in bed mobility and water chemistry along the length of Flat Brook create a “habitat window” for A. heterodon defined by bed stability (mobility index ≤1) and aragonite saturation (saturation index ≥1). We suggest the species may exist in a narrow biogeochemical window that is seasonally near saturation. Alasmidonta heterodon populations may be susceptible to climate change or anthropogenic disturbances that increase discharge, decrease groundwater inflow or chemistry, and thus affect either bed mobility or aragonite saturation. Identifying the biogeochemical microhabitats and requirements of individual mussel species and incorporating this knowledge into management decisions should enhance the conservation and restoration of endangered mussel species.
... De la même manière, en Alaska, les goélands et aigles des mers pêchent dans le rouleau du mascaret à Turnagain et Knickarm (Bartsch-Winkler et Lynch 1988, Molchan-Douthit 1998). La zone intertidale, sujette au mascaret, est aussi un zone de reproduction, et un terrain de prédilection pour la pêche : les esturgeons et les anguilles dans la rivière Severn (Grande-Bretagne), les anguilles dans la rivière Qiantang (Chine), les « striped bass » et certaines espèces de saumons et de truites en Baie de Fundy (Witts 1999, Jones 2003, Morris et al. 2003, Locke et al. 2003). Ainsi, dans la Dordogne, on pêche le Lamproie et le Mule, avant l'arrivée et juste au passage du mascaret 4 . ...
... De la même manière, la disparition, ou des changements importants, du mascaret peuvent entraîner une modification drastique de la faune aquatique. Par exemple, dans la rivière Petitcodiac, la construction d'un barrage en 1968, associée à la quasi-disparition du mascaret, a été accompagnée par l'élimination de nombreuses espèces traditionnelles de poissons , et l'apparition d'espèces « introduites » (Locke et al. 2003). ...
Tidal bores are a hydraulic phenomenon that is often not well explained and poorly documented. Herein, the writer explains what a tidal bore is, where it occurs, since when it has been observed, how it develops and why the occurrence of a bore has a significant impact on estuarine systems. In particular it is shown that a tidal bore results from a fragile balance between tidal and fluvial conditions, the estuary shape, and the meteorological conditions. Further information is available on the Internet {http://www.uq.edu.au/~e2hchans/tid_bore.html} and {http://www.uq.edu.au/~e2hchans/mascaret.html. Le mascaret est un phénomène hydraulique, parfois mythique, souvent mal expliqué, et relativement peu documenté. Dans cet article, on explique ce qu'est un mascaret, où on peut le rencontrer, depuis quand il existe, comment il se développe et pourquoi il s'agit un phénomène important pour l'environnement. En particulier, on démontre que le mascaret est un processus fragile, résultant d'une délicate balance entre les marées, le débit d'eau douce dans la rivière, la topographie de l'estuaire, et les conditions météorologiques. Le lecteur trouvera de plus amples informations sur deux sites Internet {http://www.uq.edu.au/~e2hchans/tid_bore.html} et {http://www.uq.edu.au/~e2hchans/mascaret.html}.
... De la même manière, en Alaska, les goélands et aigles des mers pêchent dans le rouleau du mascaret à Turnagain et Knickarm (Bartsch-Winkler et Lynch 1988, Molchan-Douthit 1998). La zone intertidale, sujette au mascaret, est aussi un zone de reproduction, et un terrain de prédilection pour la pêche : les esturgeons et les anguilles dans la rivière Severn (Grande-Bretagne), les anguilles dans la rivière Qiantang (Chine), les « striped bass » et certaines espèces de saumons et de truites en Baie de Fundy (Witts 1999, Jones 2003, Morris et al. 2003, Locke et al. 2003). Ainsi, dans la Dordogne, on pêche le Lamproie et le Mule, avant l'arrivée et juste au passage du mascaret 4 . ...
... De la même manière, la disparition, ou des changements importants, du mascaret peuvent entraîner une modification drastique de la faune aquatique. Par exemple, dans la rivière Petitcodiac, la construction d'un barrage en 1968, associée à la quasi-disparition du mascaret, a été accompagnée par l'élimination de nombreuses espèces traditionnelles de poissons , et l'apparition d'espèces « introduites » (Locke et al. 2003). ...
Tidal bores are a hydraulic phenomenon that is often not well explained and poorly documented. Herein, the writer explains what a tidal bore is, where it occurs, since when it has been observed, how it develops and why the occurrence of a bore has a significant impact on estuarine systems. In particular it is shown that a tidal bore results from a fragile balance between tidal and fluvial conditions, the estuary shape, and the meteorological conditions. Further information is available on the Internet {http://www.uq.edu.au/~e2hchans/tid_bore.html} and (http://www.uq.edu.au/~e2hchans/mascaret.html}.
... Unfortunately, human populations in coastal areas are three times that of the global average, resulting in estuaries becoming heavily impacted by human activities (Small & Nicholls 2003;Cox et al. 2019;Sizmur et al. 2019). These impacts have resulted in species loss, disruption of community dynamics, and habitat fragmentation (Locke et al. 2003;Crain et al. 2008;Ban et al. 2010). Further, as they grant access to inland habitats, estuaries are often hubs of industrial activities, such as logging (Simenstad et al. 1982;Musick et al. 2000), metal smelting, and pulp and paper production (Yunker et al. 2011;Sizmur et al. 2019). ...
... Unfortunately, human populations in coastal areas are three times that of the global average, resulting in estuaries becoming heavily impacted by human activities (Small & Nicholls 2003;Cox et al. 2019;Sizmur et al. 2019). These impacts have resulted in species loss, disruption of community dynamics, and habitat fragmentation (Locke et al. 2003;Crain et al. 2008;Ban et al. 2010). Further, as they grant access to inland habitats, estuaries are often hubs of industrial activities, such as logging (Simenstad et al. 1982;Musick et al. 2000), metal smelting, and pulp and paper production (Yunker et al. 2011;Sizmur et al. 2019). ...
... For anadromous fi sh, the presence of dams hinders the access of adults to spawning grounds (Zhou et al. 2014), and it increases the mortality risk of juveniles during downstream migration through entrainment against water intake screens of hydro-electrical power plants (Williams et al. 2001;Keefer et al. 2012). The large number of dams constructed in large rivers, mainly since the mid-20th century, has led to river habitat loss and modifi cation of population dynamics for many anadromous species (Locke et al. 2003;Morita et al. 2009;Hall et al. 2011;Junge et al. 2014). For example, for American shad, about 4000 km of an original 11200 km of spawning habitat have been lost due to dams (Limburg et al. 2003). ...
Introduction, anadromous fishes: who are they? Why do they migrate? When do they migrate? How do they migrate? Insights on anadromous species conservation.
... An interesting case study comes from the Petitcodiac River in the Bay of Fundy (tidal range is~7 m), where in 1968 a causeway was constructed, cutting off water and sediment to the lower 55 km of the river. This resulted in sedimentation in the abandoned channel downstream of the causeway (via tidal transport of marine sediment) and annealing the channel, which reduced its width by~90% in 12 yr (i.e., from 1 km to 100 m, (Locke et al., 2003)). The thickness of the deposited sediment reached 8 m, consistent with the tidal range. ...
Upon avulsion, abandoned deltaic distributary channels receive water and sediment delivered by a tie channel, overbank flow, and by tidal inundation from the receiving basin. The transport and deposition of sediment arising from this latter input have important impacts on delta development yet are not well constrained from field observations or numerical models. Herein, the Huanghe (Yellow River) delta, China, is used as a case study to evaluate how marine‐sourced sediment impacts abandoned channel morphology. For this system, artificial deltaic avulsions occur approximately decadally; the abandoned channels are inundated by tides, and deposition of sediment transforms the channel into a mudflat. Field data were collected from a channel abandoned 20 yr ago and included cores that penetrated the tidally deposited mud and antecedent fluvial channel sediment, topography, bathymetry surveys, and detailed time series monitoring of hydrodynamic conditions within the tidal channel and adjacent mudflat. These data are used to validate a model that predicts the rate of accumulation and grain size of sediment delivered from the tidal channel to the mudflat. The thickness of the marine‐sourced mud differs spatially by an order of magnitude and is primarily impacted by antecedent channel topography. Sediment has aggraded to an elevation approaching mean high tide, which is likely the limit of fill. As this elevation is below antecedent levees, assuming stationary relative sea level, the abandoned channel will remain a topographic low on the delta landscape and is therefore susceptible to reoccupation during future avulsions.
... As the watershed and its fisheries had been well studied by DFO researchers between the 1940s and 1960s, a form of cumulative effects assessment was conducted by qualitatively assessing the ecological value of the watershed before and after the causeway construction in 1967. This assessment considered criteria of temporal stability, uniqueness, conservation of native species, and level of disturbance (Locke et al. 2003). Subsequently, a full Environmental Impact Assessment was conducted for modification to the causeway (New Brunswick Department of Environment and Local Government 2005) and a critique of this EIA stated that based in part on the level of cumulative effects assessment conducted, "the Environmental Impact Assessment Report for Modifications to the Petitcodiac River Causeway performs very strongly in light of academic criticisms of typical Canadian EIA practices" (St. ...
The study and management of cumulative effects is an emerging field and an area of critical importance to Fisheries and Oceans Canada (DFO). Cumulative effects are defined as “…changes to the environment that are caused by an action in combination with other past, present and future human actions” (Hegmann et al. 1999) and, crucially, can result from individually minor but collectively significant actions taking place over a period of time or across an area. The need for assessment of cumulative effects is evident throughout the programs and objectives of DFO, and is required to support management decisions by multiple DFO sectors. An overarching cumulative effects strategy for DFO, would provide a consistent approach and guidance for the assessment of cumulative effects through development of standard methods that build on existing general theoretical frameworks and applications. This report collates and reviews previous and ongoing existing cumulative effects research and assessments conducted by DFO, focusing on marine ecosystems. Based on the range of existing work and needs within DFO programs, we outline a strategy for assessing cumulative effects that uses a typology of cumulative effect assessment frameworks consisting of four types: activity-based, stressor-based, species- or habitat-based, and area-based.
... Unfortunately, human populations in coastal areas are three times that of the global average, resulting in estuaries becoming heavily impacted by human activities (Small & Nicholls 2003;Cox et al. 2019;Sizmur et al. 2019). These impacts have resulted in species loss, disruption of community dynamics, and habitat fragmentation (Locke et al. 2003;Crain et al. 2008;Ban et al. 2010). Further, as they grant access to inland habitats, estuaries are often hubs of industrial activities, such as logging (Simenstad et al. 1982;Musick et al. 2000), metal smelting, and pulp and paper production (Yunker et al. 2011;Sizmur et al. 2019). ...
The Kaouk River estuary is located on the northwest coast of Vancouver Island, British Columbia, Canada, in the Treaty Settlement Lands of the Ka:'yu:'k't'h'/Che:k'tles7et'h First Nations. Stretching across the widest point of this estuary is a causeway providing road access to Fair Harbour. This causeway was observed to decrease habitat connectivity throughout the estuary, specifically limiting juvenile salmon access to high‐quality rearing habitat in the tidal marsh. As such, the causeway was breached in 2019 and a bridge was installed. Juvenile salmon were observed using the new connection and were captured both up and downstream of the causeway immediately following breaching. Post‐breach water chemistry (dissolved oxygen, pH, salinity, and temperature) near the causeway was recorded within the range of values observed throughout the estuary. Use of the breach by juvenile salmon and homogenized water chemistry indicate the project succeeded in improving habitat connectivity within the Kaouk River estuary and has enhanced juvenile salmon access to 2.7 km2 of wetland rearing habitat. This article is protected by copyright. All rights reserved.
... Dams and other obstacles reduce river connectivity and hinder both small and large migratory movements for most species (Figure 4B). Although likely to be more common than recorded in the scientific literature, there are examples indicating that dams and inability to migrate cause local extirpations of populations (Winston et al., 1991;Holmquist et al., 1998;Morita and Yamamoto, 2002;Locke et al., 2003). Obstacles can potentially also constrict larger scale migrations such as poleward or altitudinal range shifts that many species are undertaking to evade effects of climate change (Comte and Grenouillet, 2013). ...
Migration strategies in fishes comprise a rich, ecologically important, and socioeconomically valuable example of biological diversity. The variation and flexibility in migration is evident between and within individuals, populations, and species, and thereby provides a useful model system that continues to inform how ecological and evolutionary processes mold biodiversity and how biological systems respond to environmental heterogeneity and change. Migrating fishes are targeted by commercial and recreational fishing and impact the functioning of aquatic ecosystems. Sadly, many species of migrating fish are under increasing threat by exploitation, pollution, habitat destruction, dispersal barriers, overfishing, and ongoing climate change that brings modified, novel, more variable and extreme conditions and selection regimes. All this calls for protection, sustainable utilization and adaptive management. However, the situation for migrating fishes is complicated further by actions aimed at mitigating the devastating effects of such threats. Changes in river connectivity associated with removal of dispersal barriers such as dams and construction of fishways, together with compensatory breeding, and supplemental stocking can impact on gene flow and selection. How this in turn affects the dynamics, genetic structure, genetic diversity, evolutionary potential, and viability of spawning migrating fish populations remains largely unknown. In this narrative review we describe and discuss patterns, causes, and consequences of variation and flexibility in fish migration that are scientifically interesting and concern key issues within the framework of evolution and maintenance of biological diversity. We showcase how the evolutionary solutions to key questions that define migrating fish—whether or not to migrate, why to migrate, where to migrate, and when to migrate—may depend on individual characteristics and ecological conditions. We explore links between environmental change and migration strategies, and discuss whether and how threats associated with overexploitation, environmental makeovers, and management actions may differently influence vulnerability of individuals, populations, and species depending on the variation and flexibility of their migration strategies. Our goal is to provide a broad overview of knowledge in this emerging area, spur future research, and development of informed management, and ultimately promote sustainable utilization and protection of migrating fish and their ecosystems.
... Dams have historically been a leading contributor to the loss of anadromous fishes worldwide (Hall, Jordaan, & Frisk, 2012;Liermann, Nilsson, Robertson, & Ng, 2012). For anadromous species, dams can block access to high quality spawning grounds, increase competition for available spawning sites, increase migration time, create lethal water conditions during migration, and decrease offspring survival (Gosset, Rives, & Labonne, 2006;Hall et al., 2012;Harnish, Sharma, McMichael, Langshaw, & Pearsons, 2014;Locke, Hanson, Klassen, Richardson, & Aubé, 2003;Zhou, Zhao, Song, Bi, & Zhang, 2014). The multiple negative impacts of dams, combined with other anthropogenic stressors, have contributed to the local extirpation of many anadromous fish species (Beamish & Northcote, 1989;Rolls, StewartKoster, Ellison, Faggotter, & Roberts, 2014;Xin, Pengcheng, Mingzheng, Zhonghua, & Huanzhang, 2016). ...
The recent increase of river restoration projects is altering habitat connectivity for many aquatic species, increasing the chance that previously isolated populations will come into secondary contact. Anadromous and landlocked alewife (Alosa pseudoharengus) are currently undergoing secondary contact as a result of a fishway installation at Rogers Lake in Old Lyme, Connecticut. To determine the degree of pre‐zygotic isolation and potential for hybridization between alewife life history forms, we constructed spawning time distributions for two anadromous and three landlocked alewife populations using otolith derived age estimates. In addition, we analyzed long‐term data from anadromous alewife migratory spawning runs to look for trends in arrival date and spawning time. Our results indicated that anadromous alewife spawned earlier and over a shorter duration than landlocked alewife, but 3% to 13% of landlocked alewife spawning overlapped with the anadromous alewife spawning period. The degree of spawning time overlap was primarily driven by annual and population level variation in the timing of spawning by landlocked alewife, whereas the timing and duration of spawning for anadromous alewife was found to be relatively invariant among years in our study system. For alewife and many other anadromous fish species, the increase in fish passage river restoration projects in the coming decades will re‐establish habitat connectivity and may bring isolated populations into contact. Hybridization between life history forms may occur when pre‐zygotic isolating mechanisms are minimal, leading to potentially rapid ecological and evolutionary changes in restored habitats.
This article is protected by copyright. All rights reserved.
... The only known population of A. heterodon in Canada occurred in the Petitcodiac River basin, New Brunswick. However, a causeway completed in 1968 blocked anadromous fish passage including that of Atlantic salmon; loss of this host fish is thought to have caused A.heterodon extirpation, as neither the tessellated darter nor the slimy sculpin are native to the Petitcodiac River(Hanson & Locke, 2000;Locke, Hanson, Klassen, Richardson, & Aubé, 2003).Alasmidonta heterodon populations in the Delaware River, which supports an undammed mainstem and many tributaries with open stream networks, may have at least some access to migratory hosts such as striped bass, as may A. heterodon populations in Chesapeake Bay region. This mussel species has historically inhabited numerous streams adjacent to tidal areas of both the Delaware and Chesapeake Bay estuaries where striped bass are well-documented (USFWS, 1993). ...
Host fishes play a crucial role in survival and dispersal of freshwater mussels (Unionoida), particularly rare unionids at conservation risk. Intraspecific variation in host use is not well understood for many mussels, including the endangered dwarf wedgemussel ( Alasmidonta heterodon ) in the USA.
Host suitability of 33 fish species for dwarf wedgemussel glochidia (larvae) from the Delaware and Connecticut river basins was tested in laboratory experiments over 9 years. Relative suitability of three different populations of a single host fish, the tessellated darter ( Etheostoma olmstedi ), from locations in the Connecticut, Delaware, and Susquehanna river basins, was also tested.
Connecticut River basin A. heterodon metamorphosed into juvenile mussels on tessellated darter, slimy sculpin ( Cottus cognatus ), and Atlantic salmon ( Salmo salar ) parr. Delaware River basin mussels metamorphosed using these three species, as well as brown trout ( Salmo trutta ), banded killifish ( Fundulus diaphanus ), mottled sculpin ( Cottus bairdii ), striped bass ( Morone saxatilis ), and shield darter ( Percina peltata ). Atlantic salmon, striped bass, and sculpins were highly effective hosts, frequently generating 5+ juveniles per fish (JPF) and metamorphosis success (MS; proportion of attaching larvae that successfully metamorphose) ≥ 0.4, and producing juveniles in repeated trials.
In experiments on tessellated darters, mean JPF and MS values decreased as isolation between the mussel source (Connecticut River) and each fish source increased; mean JPF = 10.45, 6.85, 4.14, and mean MS = 0.50, 0.41, and 0.34 in Connecticut, Delaware, and Susquehanna river darters, respectively. Host suitability of individual darters was highly variable (JPF = 2–11; MS = 0.20–1.0).
The results show that mussel–host fish compatibility in A. heterodon differs among Atlantic coastal rivers, and suggest that hosts including anadromous Atlantic salmon and striped bass may help sustain A. heterodon in parts of its range. Continued examination of host use variation, migratory host roles, and mussel–fish interactions in the wild is critical in conservation of A. heterodon and other vulnerable mussel species.
... Figure 1 presents photographs of tidal bores propagating upstream. A tidal bore has a significant impact on the environmental system and the ecology of the river mouth (Rulifson and Tull 1999;Locke et al. 2003;Ezer et al. 2008). Tidal bores can also be dangerous, impacting adversely on man-made structures ( Fig. 1) and endangering lives. ...
A tidal bore is a hydrodynamic shock, surging upstream in some shallow-water bays and estuaries during the flood tide under large tidal range. This study investigates experimentally the propagation of tidal bores over a large cylindrical roughness element, representative of damaged bridge pier foundation. In the initially steady flow, the large cylindrical element generated a wake region, with extents comparable to steady flow literature. During the tidal bore propagation, the presence of the element had negligible effect on the free-surface properties, but a significant impact in terms of the instantaneous velocity and Reynolds stresses. This resulted in longer transient recirculation both upstream and downstream of the element and larger maximum velocity recirculation magnitudes, as well as enhanced turbulent stress levels and potential bed erosion around the large element, within two diameters from the element centre. The results showed the potential development of a large scour hole around the cylindrical element.
... For anadromous fi sh, the presence of dams hinders the access of adults to spawning grounds (Zhou et al. 2014), and it increases the mortality risk of juveniles during downstream migration through entrainment against water intake screens of hydro-electrical power plants (Williams et al. 2001;Keefer et al. 2012). The large number of dams constructed in large rivers, mainly since the mid-20th century, has led to river habitat loss and modifi cation of population dynamics for many anadromous species (Locke et al. 2003;Morita et al. 2009;Hall et al. 2011;Junge et al. 2014). For example, for American shad, about 4000 km of an original 11200 km of spawning habitat have been lost due to dams (Limburg et al. 2003). ...
... Based upon overlapping distributions, it was hypothesized that the host for the dwarf wedgemussel was the American shad, as its former spawning and juvenile rearing sites corresponded almost exactly to the distribution of A. heterodon in the 1960s. The American shad was eliminated almost immediately by the construction of the causeway (Locke et al., 2003). ...
Two native groups represent the freshwater bivalves of North America: the freshwater mussels (Unionoidea) and the pill, fingernail, and pea clams (Sphaeriidae). There are also two widely publicized invasive genera, Corbicula and Dreissena. These mollusks have interesting and important ecological interactions with their environments, not the least of which is their relationship to humans. The bias of this chapter is toward the freshwater mussels. They are the numerically dominant group, with 10 times more species, and considerably more data are available on them. This chapter covers general biology, including internal and external anatomy, physiology, and reproduction. General ecology is discussed, including life-cycles, age and growth, and biotic interactions. The role of freshwater biovalves as biomonitors is reviewed.
... Based upon overlapping distributions, it was hypothesized that the host for the dwarf wedgemussel was the American shad, as its former spawning and juvenile rearing sites corresponded almost exactly to the distribution of A. heterodon in the 1960s. The American shad was eliminated almost immediately by the construction of the causeway [359] . ...
This chapter introduces general biology, morphology, ecology, physiology, life histories, evolution, and classification of bivalve molluscs found in freshwaters of North America. The freshwater bivalves of North America are represented by two native groups, the freshwater mussels (Unionoidea) and the pill, fingernail, and pea clams (Sphaeriidae), as well as two widely publicized invasive genera, Corbicula and Dreissena. The North American fauna of freshwater bivalves is the richest in the world, with about 350 species of mussels and clams, nine or so of which are exotic. The latter includes Asian clams and zebra mussels. Molluscs, are major deposit and suspension feeders within permanent lakes, streams, and large rivers, where they are often the largest invertebrates in body mass. Freshwater mussels are considered to be part of a guild of freshwater, sedentary filter feeders. These molluscs have interesting and important ecological interactions with their environments. Given the processes they perform and their high biomass in rivers where they are abundant, freshwater mussels have the potential to have strong effects by modifying the habitat and controlling the availability of resources to other organisms.
... The causeway over the Petitcodiac River blocked tidal flow upriver and led to significant trapping and storage of silt on the seawards side of the causeway (Fig. 7). The causeway also led to a major decrease in the fish population in the Petitcodiac (Locke et al. 2003) and a decrease in the amplitude of the tidal bore from an average 1 m to approximately 75 cm (NBDELG 2005). Approximately 10 × 10 6 m 3 of mud accumulated in the 4.7 km of river directly in front of the causeway in the first 3 years after its construction (1968)(1969)(1970)(1971), resulting in a decrease in channel width from 1 km to 100 m, and a 21 × 10 6 m 3 decrease in the tidal prism volume (Bray et al. 1982;Haralampides & Rodriguez 2006). ...
In Chignecto Bay, upper Bay of Fundy, Canada, the muddy tidal flats exhibit distinctive sedimentological and ichnological characteristics indicative of winter conditions and the development of ice. From late spring to autumn (May–October: mean temperature +13.6 °C), the mud flats sustain a high infaunal biomass and sediment deposition is dominated by tidal processes. Neap–spring tidal rhythmites, fluid-mud deposition and high levels of bioturbation are all characteristic of summer deposits. During the winter, temperatures remain below zero (December–March: mean temperature −6.3 °C), and ice forms in the bay and periodically on the mud flats. Ice rafts and blocks are common on the tidal-flat surface, and these blocks deform the muddy sediment, cut deep scours and deposit allochthonous sediment (including gravel) across the flats. Intermittent storms in the autumn and winter also contribute to sediment scouring and erosion. Annual die-offs of infauna are reflected by reduced bioturbation in winter deposits. Each spring, renewed larval recruitment and opportunistic colonization results in increasing levels of bioturbation, and the trace suite is dominated by a low-diversity assemblage of diminutive, vertical burrows. The summer–winter cyclicity in infaunal colonization manifests, ichnologically, as a distinctive bioturbated–non-bioturbated bedset character.
Infaunal populations in Chignecto Bay peak in the late spring and in the late summer–early autumn. Both population peaks are exploited by vertebrates, including migrating Atlantic sturgeon (late spring) and migratory shorebirds (late summer–early autumn). In particular, the upper Bay of Fundy, including Chignecto Bay, is a staging ground for approximately 42–74% of the world’s Semipalmated sandpipers (Calidris pusilla) on their annual migration from the Arctic to South America. Fortunately, anthropogenic modification of Chignecto Bay, and its associated bays and rivers (e.g. construction and dismantling of a causeway over the Petitcodiac River), has not had a significant effect, to date, on the mud-flat habitat or the infaunal biomass.
... A causeway with ineffective fish passage was constructed near the head of tide in the Petitcodiac River in 1968. This barrier completely blocked the access of migratory fishes to upstream spawning habitat and dramatically reduced the abundance of alewife and blueback herring in the drainage (Locke et al. 2003). Increased spatiotemporal overlap of spawning adults below the causeway coupled with population declines may have increased the chances of interspecific matings (Reyer 2008). ...
Most evidence for hybrid swarm formation stemming from anthropogenic habitat disturbance comes from the breakdown of reproductive isolation between incipient species, or introgression between allopatric species following secondary contact. Human impacts on hybridization between divergent species that naturally occur in sympatry has received considerably less attention. Theory predicts that reinforcement should act to preserve reproductive isolation under such circumstances, potentially making reproductive barriers resistant to human habitat alteration. Using 15 microsatellites we examined hybridization between sympatric populations of alewife (Alosa pseudoharengus) and blueback herring (A. aestivalis) to test whether the frequency of hybridization and pattern of introgression have been impacted by the construction of a dam that isolated formerly anadromous populations of both species in a landlocked freshwater reservoir. The frequency of hybridization and pattern of introgression differed markedly between anadromous and landlocked populations. The range-wide frequency of hybridization among anadromous populations was generally 0-8%, whereas all landlocked individuals were hybrids. Although neutral introgression was observed among anadromous hybrids, directional introgression leading to increased prevalence of alewife genotypes was detected among landlocked hybrids. We demonstrate that habitat alteration can lead to hybrid swarm formation between divergent species that naturally occur sympatrically, and provide empirical evidence that reinforcement does not always sustain reproductive isolation under such circumstances. This article is protected by copyright. All rights reserved.
... The tidal bores of the Couesnon (France) and Petitcodiac (Canada) rivers almost disappeared after construction of an upstream barrage. At Petitcodiac, this yielded the elimination of several diadromous fish species, including the American shad, Atlantic salmon, Atlantic tomcod, striped bass and sturgeon [77]. There are numerous visual accounts of tidal bores, but field measurements are very limited. ...
The hydraulic jump is the sudden transition from a high-velocity open channel flow regime to a subcritical flow motion. The flow properties may be solved using continuity and momentum considerations. In this review paper, recent advances in turbulent hydraulic jumps are developed: the non-breaking undular hydraulic jump, the positive surge and tidal bore, and the air bubble entrainment in hydraulic jumps with roller. The review paper demonstrates that the hydraulic jump is a fascinating turbulent flow motion and the present knowledge is insufficient, especially at the scales of environmental and geophysical flows.
... The tidal bores of the Colorado (Mexico), Couesnon (France) and Petitcodiac (Canada) Rivers almost disappeared after construction of upstream barrage(s). At Petitcodiac, this yielded the elimination of several diadromous fish species, including the American shad, Atlantic salmon, Atlantic tomcod, striped bass and sturgeon [39]. The Severn Barrage on the Bristol Channel would mark the disappearance of the Severn River tidal bore (UK) if the project goes ahead. ...
A tidal bore is a series of waves propagating upstream as the tidal flow turns to rising. It forms during the spring tide conditions when the tidal range exceeds 5-6 m and the flood tide is confined to a narrow funnelled estuary with low freshwater levels. A tidal bore is associated with a massive mixing of the estuarine waters that stirs the organic matter and creates some rich fishing grounds. Its occurrence is essential to many ecological processes and the survival of unique eco-systems. The tidal bore is also an integral part of the cultural heritage in many regions: the Qiantang River bore in China, the Severn River bore in UK, the Dordogne River in France. In this contribution, the environmental, ecological and cultural impacts of tidal bores are reviewed, explained and discussed.
... The tidal bores of the Colorado (Mexico), Couesnon (France) and Petitcodiac (Canada) Rivers almost disappeared after construction of upstream barrage(s). At Petitcodiac, this yielded the elimination of several diadromous fish species, including the American shad, Atlantic salmon, Atlantic tomcod, striped bass and sturgeon [37]. The Severn Barrage on the Bristol Channel would mark the disappearance of the Severn River tidal bore (UK). ...
A tidal bore is a series of waves propagating upstream as the tidal flow turns to rising. It forms during the spring tide conditions when the tidal range exceeds 4 to 6 m and the flood tide is confined to a narrow funnelled estuary with low freshwater levels. Tidal bores are locally called mascaret, pororoca, benak, bono, burro and aegir. A tidal bore is associated with a massive mixing of the estuarine waters that stirs the organic matter and creates some rich fishing grounds. Its occurrence is essential to many ecological processes and the survival of unique eco-systems. The tidal bore is also an integral part of the cultural heritage in many regions: the Qiantang River bore in China, the Severn River bore in UK, the Dordogne River in France. In this contribution, the environmental, ecological and cultural impacts of tidal bores are detailed and discussed.
... The tidal bores of the Couesnon (France) and Petitcodiac (Canada) Rivers almost disappeared after construction of an upstream barrage. At Petitcodiac, this yielded the elimination of several diadromous fish species, including the American shad, Atlantic salmon, Atlantic tomcod, striped bass and sturgeon (Locke et al. 2003). There are visual accounts of tidal bores, but field measurements are rare. ...
From the "boring boar" of Astérix and Obélix, to the tidal bore of the Indus River that wiped out the fleet of Alexander the Great, the English word "bore" has been used for a broad range of meanings. Similarly, the expressions "digital information revolution" and "electronic publishing" are used broadly. Herein the impact of digital publishing is presented in the context of hydraulic engineering, research and practice, and it is compared with the impact of a tidal bore on an estuarine system. Like a tidal bore, digital publishing is advancing at a fast pace and cannot be stopped, but the advance is fascinating. It is argued that an increased number of unethical behaviours has been recently observed. While these might be linked with the development of open access tools, the open access repositories (OARs) have expanded the freely-accessible bibliographic references available by engineers and researchers. The OARs provide further genuine information on the impact of research publications with challenging outcomes. The development of research metrics is also discussed. Simplistic naive indicators used by commercial databases are inappropriate, and a series of newer weighted research metrics are presented with a focus on the individual scholarship. Digital publishing and electronic "band-aids" will never replace scholarship and critical thinking, although they constitute the new tools of professionals, researchers and academics.
Coastlines in Atlantic Canada are influenced by microtidal, mesotidal, macrotidal, and hypertidal regimes. Although the hypertidal inner Bay of Fundy has attracted the most attention from geomorphologists and visitors, all atlantic tidal environments are marked by interesting and distinctive coastscapes, influenced by pre-existing topography, coastal bedrock lithology and Quaternary sediment, sea ice activity, and subtidal, intertidal, and supratidal vegetation. The hypertidal-macrotidal Bay of Fundy of New Brunswick and Nova Scotia is marked by extensive tidal flats and channels. Saltmarshes and barrier islands characterize the mesotidal Gulf of St. Lawrence coastlines of New Brunswick and Prince Edward Island. Tides and sea ice influence mesotidal-upper microtidal coastlines of Newfoundland and Labrador. In addition to their geomorphic significance, atlantic Canadian tidal coastlines also are valuable resources from multiple ecological and socio-economic viewpoints. Subtidal and intertidal areas support a variety of organisms and ecological communities. Saltmarshes are marked by sequences of communities conditioned by salinity and terrestrial input. Tide-dominated coastlines have been occupied by humans since shortly after deglaciation, and tidal activity has significant impacts on human coastal utilization. Interest in exploiting tidal energy remains high, but must be balanced against potential ecological impacts. Coastal tourism is a significant economic driver in Atlantic Canada, with tidal coastlines representing major attractions.
This chapter begins with a brief general introduction on the role of the atmosphere in generating waves in the oceans and then provides a recently identified scientific explanation to the vexed question of the historical biblical crossing of the Red Sea by Israelites led by Moses. This is followed by a description of various aspects of internal waves the invisible colossal waves below sea surface—and their influence on climate and fisheries. Intricate tidal motions in topographically complex water bodies are addressed next. Here tidal bores are given considerable attention. This chapter ends with a discussion on oceanic temperature inversion, the process of a subsurface warm water layer sandwiched between colder waters above and below. Here particular attention is paid to the climatic impact of a temperature inversion.
Freshwater mussel distributions are heavily reliant upon the range and movement of host fishes and are subject to range restrictions when fish migration is blocked. The Columbia Dam on the Broad River in Columbia, SC, has been a barrier to the migration of anadromous species and other fish in the river since 1824. As a result, 5 freshwater mussel species are restricted to reaches of the river downstream of the dam. In 2006, a fish passage was created to facilitate fish movement between stream reaches above and below the dam. Fish hosts that use the passage could facilitate the recolonization of reaches above the dam by freshwater mussels. We conducted laboratory trials to determine the fish hosts of 4 of the species limited to reaches below the dam. The most suitable hosts for Lampsilis cariosa (Yellow Lampmussel) were Morone chrysops (White Bass), Morone saxatilis (Striped Bass), and Pomoxis nigromaculatus (Black Crappie), whereas Micropterus salmoides (Largemouth Bass) and Micropterus dolomieu (Smallmouth Bass) transformed fewer juvenile mussels. Lampsilis siliquoidea (Fatmucket) hosts were Largemouth Bass and Perca flavescens (Yellow Perch). Yellow Perch, Largemouth Bass, Lepomis macrochirus (Bluegill), and Lepomis gibossus (Pumpkinseed) were the best hosts for Ligumia nasuta (Eastern Pondmussel). We suspected that Elliptio roanokensis (Roanoke Slabshell) used anadromous fishes as hosts because its distribution is limited to mainstem rivers below the downstreammost dam. We confirmed that 2 Clupeidae, Dorosoma cepedianum (Gizzard Shad) and Alosa aestivalis (Blueback Herring), and 1 Moronidae, Morone americana (White Perch), are hosts for Roanoke Slabshell. Many of the host-fish species identified in this study are highly mobile, and we expect the range of these mussels to eventually expand upstream of the Columbia Dam as fish make use of the new passage.
A numerical model was developed based on the Cubic-Interpolated Pseudo-particle (CIP) Combined Unified Procedure (CIP-CUP or C-CUP) method equipped with a Large Eddy Simulation (LES) model and a re-initialization method. The model was validated and applied to the tidal bore flow with a weak breaking front. In the tidal bore flow, the model equipped with a LES turbulence model reproduced accurately the large deformation of the free surface during the bore formation by rapid closure of a downstream gate. The free-surface profile and surge front celerity data were in good agreement with the experimental data of [Koch and Chanson 2009, J. Hyd. Res. IAHR]. At a fixed sampling location, the numerical results showed the existence of some short-lived flow reversal next to the bed immediately after the bore front passage. This flow feature was documented by [Koch and Chanson 2009] and [Chanson 2009, Eur. J. Mech. B. Fluids].
The Vu Gia - Thu Bon River Basin in central Vietnam is subject to extensive hydropower development, with eight major and at least 34 minor hydropower installations planned for completion over the next 10 years. This intense clustering of hydropower developments has the potential to impact on aquatic fauna and ecosystems extensively. We sampled freshwater and estuarine fish across the river basin to evaluate the current status of the fish fauna, to determine the extent of zonal and habitat specialisation, to determine the prevalence of migration as a component of life-history strategies, to evaluate the likely magnitude of impacts, and to highlight areas where management intervention is needed and where more extensive study is most urgently required. Given the current high levels of exploitation, the fish fauna appeared surprisingly intact; however, a number of attributes of the fauna, such as the prevalence of migration as a life-history tactic, make this fauna particularly vulnerable to the impacts of hydropower development. Without extensive mitigation, the combinations of habitat alteration in dam and diversion areas and the imposition of a proliferation of barriers to migration will lead to severe population fragmentation, increasing the potential for local extinction, and severely compromise opportunities for recolonisation.
The upper estuary of the macrotidal Petitcodiac River, New Brunswick, Canada, was converted to a freshwater impoundment by construction of a causeway in 1968. Thirty years later, zooplankton community structure in the impoundment was characteristic of a disturbed ecosystem. The depauperate zooplankton consisted of a mixture of freshwater and marine/brackish taxa, but was not typical of regional estuaries or lakes. The causeway dam was an obstacle to fish migration, and several anadromous species that would formerly have been represented in the ichthyoplankton were absent. The invertebrate plankton community was dominated by rotifers, likely as a result of frequent water level fluctuations, and highly suspended sediment levels in the water column. Estuarine/marine calanoids (Eurytemora affinis, Temora longicornis, Centropages typicus, Tortanus discaudatus), the mysid Neomysis americana, and Cancer crab zoeae were collected in fresh water up to 14km upstream of the causeway.
The sand dunes in coastal regions of South Korea are important ecosystems because of their small size, the rare species found in this habitat, and the beautiful landscapes they create. This study investigated the current vegetative status of sand dunes on three representative coasts of the Korean peninsula, and on the coasts of Cheju Island, and assessed the conditions caused by invasive plants. The relationships between the degree of invasion and 14 environmental variables were studied. Plots of sand dunes along line transects perpendicular to the coastal lines were established to estimate vegetative species coverage. TWINSPAN (Two-Way Indicator Species Analysis), CCA (Canonical Correspondence Analysis), and DCCA (Detrended Canonical Correspondence Analysis) were performed to classify communities on sand dunes and assess species composition variation. Carex kobomugi, Elymus mollis, and Vitex rotundifolia were found to be the dominant species plotted on the east, the west, and the peripheral coasts of Cheju Island, respectively. Vegetation on the south coast was totally extinct. The 19 communities, including representative C. kobomugi, C. kobomugi–Ixeris repens, C. kobomugi–Oenothera biennis, E. mollis, Lolium multiflorum–Calystegia soldanella, and V. rotundifolia–C. kobomugi, were all classified according to TWINSPAN. Oenothera biennis and L. multiflorum were exotics observed within these native communities. CCA showed that invasive native and exotic species distribution was segregated significantly, according to disturbance level, exotic species number, gravel, sand and silt contents, as well as vegetation size. It further revealed that human disturbance can strongly favor the settlement of invasive and exotic species. Restoration options to reduce exotic plants in the South Korean sand dune areas were found to be the introduction of native plant species from one sand dune into other sand dune areas, prohibition of building and the introduction of exotic soils, and conservation of surrounding sand dune areas.
In macro-tidal estuaries, a tidal bore may form during spring tide conditions when the flood tide is confined to a narrow channel. Most field occurrences showed well-defined undulations behind the leading wave, that is an undular bore process. Herein detailed free-surface and turbulence measurements were performed beneath undular bore fronts using side-looking acoustic Doppler velocimetry and non-intrusive free-surface measurement devices in a laboratory channel. Undular bores were observed for Froude numbers less than 1.7 which compared favourably with past studies. Velocity measurements with a temporal resolution of 50 Hz showed a marked effect of the bore passage. Longitudinal velocities were characterised by rapid flow deceleration at all vertical elevations, while large fluctuations of transverse velocities were recorded beneath the front. Turbulent Reynolds stress data highlighted high levels in the lower flow region including next to the bed. Maximum normal and tangential turbulent stresses were observed immediately upstream of and at wave crests.
The hydraulic jump is the sudden transition from a high-velocity open channel flow regime to a subcritical flow motion. The flow properties may be solved using continuity and momentum considerations. In this plenary lecture, recent advances in turbulent hydraulic jumps are reviewed: the non-breaking undular hydraulic jump, the positive surge and tidal bore, and the air bubble entrainment in hydraulic jumps with roller. This keynote lecture demonstrates that the hydraulic jump is a fascinating turbulent flow motion that remains poorly understood.
We present a novel microfluidic concept to enable a fast colorimetric alcohol assay from a single droplet of whole blood. The reduced turn-around time of 150 seconds is, on the one hand, achieved by a full process integration including metering, mixing with reagents, and sedimentation of cellular constituents. On the other hand, our novel total internal reflection (TIR) scheme allows to monitor the increase of the absorbance values in real-time. Thus, the saturation values can be predicted accurately based on an extrapolation of real-time measurements acquired during a 100 second initial period of rotation. Additionally, we present a metering structure to define nanolitre sample volumes at a coefficient of variation (CV) below 5%.
The study reports estimates of declines of natural ecosystems in the US provides a rationale for ecosystem-level conservation, discusses decline and threat as criteria for conservation, and relates ecosystem losses to endangerment at species and population levels. The methodology for this report consisted of a literature review and a survey of conservation agencies and professionals. The result of this preliminary study indicated significant losses of biodiversity at the ecosystem level in the US. Losses of all kinds of ecosystems have been most pronounced in the South, Northeast, and Midwest, and in California. Integrated conservation plans for all ecosystems should be developed in each ecoregion of the US, starting with types and regions that sustained the greatest losses and are at greatest risk for further loss. Ecosystem conservation need not be restricted to pristine sites, which are now almost nonexistent. -from Authors
Changes in hydrology, and developments in morphology, water quality, and ecology of the Rhine-Meuse estuary after its enclosure
in 1970 are analyzed on the basis of existing monitoring data. Annual averages of ammonium, nitrate plus nitrite, total phosphate,
total lead, and chlorophyll-a concentrations as well as transparency of the water are presented. Abundances of some water bird species are given for the
period 1970–1993, and the relative fish biomass for the period 1971–1988 is discussed. The gradual evolution led toward the
dominance of bream. The area has developed toward a system with generally low natural ecological values. Ecological impacts
of present sluice management are discussed and include the accumulation of contaminated sediments, disappearance of intertidal
areas and nursery grounds for fish, disturbance of fish migration, and less mixing of river and seawater. Recent policy developments
have brought the present management of the Haringvliet sluices back in to discussion. A recent policy document has presented
several management alternatives, including partial and complete reopening of the sluices to permit saltwater intrusion. Three
management options are compared in terms of costs and ecological benefits. It is concluded that a complete reopening, and
thus a partial restoration of the estuarine characteristics, is most beneficial for the ecosystems of the area itselt, for
the upstream Rhine and Meuse rivers, and for the adjacent North Sea, but costs amount to about 600 million US $.
The watershed of the Petitcodiac River, New Brunswick, is the only recorded location of the Dwarf Wedgemussel, Alasmidonta heterodon (Lea 1830), in Canada. The species was last collected in the Petitcodiac watershed in 1960, at which time it was considered to be common in the freshwater reaches of the Petitcodiac River and one of its major tributaries, the North River. Surveys in 1984, 1997 and 1998 failed to detect any specimens and the Dwarf Wedgemussel was classified as Extirpated by the Committee on Status of Endangered Wildlife in Canada (COSEWIC) in April 1999. The disappearance of the species from Canadian waters was probably caused by the construction of a causeway across the tidal portion of the Petitcodiac River in 1967-1968 and resultant exclusion of a diadromous fish species required for completion of the glochidial stage of the Dwarf Wedgemussel's lifecycle. Local extirpations of the Dwarf Wedgemussel from much of its American range have also been linked to dam construction, which blocked migration of anadromous fishes.
Five species of freshwater mussels were collected in a survey of 66 sites in the Petitcodiac River system, New Brunswick. One tributary, the North River, was almost devoid of all species - Apparently due to habitat degradation associated with poor agricultural practices. The Eastern Pearlshell (Margaritifera margaritifera Linnaeus 1758) was common in most of the running water portion of the river system and was the only species present at 22 sites. The Eastern Floater (Pyganodon cataracta Say 1817) was restricted to habitats with fine sediments in the main Petitcodiac River and the lower 2 km of the Little River, and in two reservoirs. The Eastern Elliptio (Elliptio complanata Lightfoot 1786) was common in areas of sand or fine gravel in slower-flowing sections of the main Petitcodiac River and the Anagance River but was absent from the Little and Pollett rivers and Turtle Creek. The Brook Floater (Alasmidonta varicosa Lamarck 1819) was locally common on sand and fine gravel substrates in the lower 6 km of the Little River and also occurred in widely scattered patches in the main Petitcodiac River. The Triangle Floater (A. undulata Say 1817) shared the same general distribution as the Brook Floater but we seldom found more than five individuals of it at any site.
A freshwater headpond was created in 1968 when a causeway was builtacross a tidal portion of the Petitcodiac River, New Brunswick, Canada. In the32-year history of this tidal barrier, there have been numerous water-leveldrawdowns to manage risk of flooding (relatively minor and of short duration)and to permit passage of anadromous fishes past the dam structure (often ofseveral weeks duration). Following five years of routine management to preventflooding, there were three major water-level drawdowns that fully exposed thelittoral zone to air for varying lengths of time during the spring of 1997 (7days), 1998 (19 days), and 1999 (55 days). The 1998 and 1999 drawdowns resultedin significant decreases in biomass of macrophytes and benthicmacroinvertebrates in the littoral and sublittoral zones, compared to 1997. Thelargest decrease occurred between 1997 and 1998 when populations of mostspecieswere largely eliminated. The remaining species were those resilient toprolongedexposure to the atmosphere. The only macrophyte to increase in biomass over thethree years was Polygonum lapathifolium, which formedimpenetrable mats in 1999. Hexagenia limbata in thesublittoral zone was the only benthic invertebrate species to increase inbiomass. The age distribution of the eastern floater (Pyganodoncataracta) population suggested that a major drawdown accompanied bysalt-water intrusion had eliminated the entire freshwater community in 1988.Thegoals of allowing passage of anadromous fishes past the dam structure and thedevelopment of a stable, artificial, freshwater-lake community appear to beincompatible.
In 1968 about 21 km of the upper end of the Petitcodiac River estuary was cut off as a result of the construction of a causeway, the associated control structures, and a fish passage facility. The primary purposes of these engineering works are to provide a highway link across the estuary and to protect upstream agricultural lands from flooding during periods of high tides.Some of the practical problems that have occurred in the Petitcodiac River estuary as a result of the construction of the causeway are presented in this paper. These problems include: major geomorphological changes, annual changes in bed level near the causeway, beach formation upstream of the causeway, and net upstream transport of sediment through the fishway at the control structure.No detailed analytical solutions are presented due to the expense of extensive data collection and the difficulty of formulating adequate models for such physical systems. However, examples are given to show that limited field data and observations may be used to provide order-of-magnitudc estimates of anticipated changes and to develop an understanding of the dominant processes that are active in such an environment.
Allele frequency data from eight microsatellite loci provide evidence of highly significant genetic differentiation among stocks of Atlantic salmon Salmo salar L. from the Bay of Fundy, eastern and north-western Nova Scotia and Newfoundland. Estimates of genetic structure (RST and θ) were significant both among all samples taken from the different geographical locations and among samples from geographical regions for which more than one stock was sampled. Samples from the Bay of Fundy taken from stocks which are phenotypically and behaviourally diverse showed particularly high levels of genetic structure. Rogers', allele sharing and (δμ)2 distances also revealed significant differences among stock samples and were significantly correlated [Rogers' and (δμ)2] with sea distance between rivers. Results suggest that stocks of Atlantic salmon in eastern Canada are highly diverse genetically and that this should be an important consideration in any management programme for stocks in the area.
Not available for use outside of the University of New Brunswick.
Study of operational problems, Petitcodiac River causeway, Moncton, N.B. Report to New Brunswick Department of Transportation
- Adi Ltd
ADI Ltd 1979. Study of operational problems, Petitcodiac River causeway, Moncton, N.B. Report to New Brunswick Department of Transportation, Fredericton, NB. 122. pp.
Analysis of options for the future of the Petitcodiac River dam and causeway
- Adi Ltd
- Gillis Washburn
- Associates
ADI Ltd., and Washburn and Gillis Associates Ltd 1992. Analysis of options for the future of the Petitcodiac River dam and causeway. Report to New Brunswick Dept. of Transportation, Fredericton, NB. 167. pp.
Chlorophyll a and nutrient concentrations in the Petitcodiac reservoir during the ice-free seasons of 1998 and 1999. P. 231-255 Petitcodiac River Trial Gate Opening project
- C I Aubé
- A Locke
Aubé, C. I. and A. Locke. 2000a. Chlorophyll a and nutrient concentrations in the Petitcodiac reservoir during the ice-free seasons of 1998 and 1999. P. 231-255. In Environmental Monitoring Working Group. 2000. Environmental Monitoring of the Petitcodiac River system, 1999: Petitcodiac River Trial Gate Opening project. 308. pp.
Hydrology of the Petitcodiac River basin in New Brunswick
- D Caissie
Caissie, D. 2000. Hydrology of the Petitcodiac River basin in New Brunswick. Canadian Technical Report of Fisheries and Aquatic Sciences 2301. 26. pp.
Report on 1999 DFO fisheries monitoring in Lobster Fishing Area 35 relative to the Petitcodiac River causeway. Pp. 77-94 Petitcodiac River Trial Gate Opening project
- P Lawton
Lawton, P. and D. A. Robichaud. 2000. Report on 1999 DFO fisheries monitoring in Lobster Fishing Area 35 relative to the Petitcodiac River causeway. Pp. 77-94. In Environmental Monitoring Working Group. Environmental Monitoring of the Petitcodiac River system. 1999. Petitcodiac River Trial Gate Opening project. 308. pp.
Fish communities of the Petitcodiac River reservoir and tributaries in 1999. Pp. 123-162 Environmental Monitoring of the Petitcodiac River system Petitcodiac River Trial Gate Opening project
- A Locke
Locke, A. 2000. Fish communities of the Petitcodiac River reservoir and tributaries in 1999. Pp. 123-162. In Environmental Monitoring Working Group. Environmental Monitoring of the Petitcodiac River system. 1999. Petitcodiac River Trial Gate Opening project. 308. pp.
Annotated bibliography of aquatic biology and habitat of the Petitcodiac River system, New Brunswick, Part 2
- A Locke
Locke, A. 2001. Annotated bibliography of aquatic biology and habitat of the Petitcodiac River system, New Brunswick, Part 2. Canadian Manuscript Report of Fisheries and LockeScience 2561. 62. pp.
Annotated bibliography of the aquatic biology and habitat of the Petitcodiac River system
- A Locke
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Locke, A. and R. Bernier. 2000. Annotated bibliography of the aquatic biology and habitat of the Petitcodiac River system. Canadian Manuscript Report of Fisheries and Aquatic Sciences 2518. 162. pp. (also available on the Internet at
Review of the Petitcodiac River causeway and fish passage issues Report of the Special Advisor to the Minister of Fisheries and Oceans Canada
- E Niles
Niles, E. 2001. Review of the Petitcodiac River causeway and fish passage issues. Report of the Special Advisor to the Minister of Fisheries and Oceans Canada. 75. pp. (available on the Internet at
Anadromous fish stocks in the Petitcodiac River system and the Moncton causeway: a status report Draft of a Fisheries and Marine Service Manuscript Report
- J R Semple
Semple, J. R. 1979. Anadromous fish stocks in the Petitcodiac River system and the Moncton causeway: a status report. Draft of a Fisheries and Marine Service Manuscript Report. Halifax, NS. 29. pp.
PEI causeway removal policy and its implementation. Pp. 41-51 Tidal barriers in the inner Bay of Fundy: Ecosystem impacts and restoration opportunities. Conservation Council of New Brunswick
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Trainor, G. and B. Thompson. 2000. PEI causeway removal policy and its implementation. Pp. 41-51. In Percy, J. and J. Harvey (Eds.) Tidal barriers in the inner Bay of Fundy: Ecosystem impacts and restoration opportunities. Conservation Council of New Brunswick, Fredericton, NB.
Salmon spawn in restored reach of Kennebec
- D Watts
Watts, D. 2001. Salmon spawn in restored reach of Kennebec. Atlantic Salmon Journal, Spring 2001. 19.
Effects of muskrat predation on Naiads. Pp. 163-184
- Zahner
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Zahner-Meike, E. and J. M. Hanson. 2000. Effects of muskrat predation on Naiads. Pp. 163-184. In G. Bauer and K. Wachtler (Eds.) Ecology and evolutionary biology of the freshwater mussels Unionoidea. Ecological Studies Vol. 145. Springer Verlag, Berlin, Germany.