Developing environmental flow targets for benthic macroinvertebrates in large rivers using hydraulic habitat associations and taxa thresholds

Holistic environmental flows frameworks are built on our understanding of key flow-ecology relationships that support sensitive taxa and critical ecosystem functions under different flow and water level scenarios. Most research on flow-ecology relationships has typically focused on small systems, with less known about flow as-sociations, indicator taxa, and environmental thresholds of assemblage change along hydraulic gradients of large non-wadeable rivers. We assessed benthic macroinvertebrate assemblage structure and applied Taxa Indicator Threshold ANalysis (TITAN) on biomonitoring data collected during a six-year period in the Wolastoq | Saint John River in Atlantic Canada. Flow velocity was strongly associated with the distribution and relative abundance of benthic macroinvertebrates in the river, and taxon associations reflected functional adaptations to flow. We identified 33 genus-level indicator taxa that were either positively or negatively associated with flow velocity. Weaker taxa responses were shown for the gradient in median substrate particle size where 22 negatively and positively responding taxa were identified. We predicted changes in indicator taxon abundance under different flow scenarios using a hydrodynamic model, and characterised the distribution and availability of suitable hydraulic habitat patches within a 20 km reach downstream of a large hydropower generating station. These observations set the stage for the development of ecologically-based flow targets to support holistic environmental flow management in large rivers

Migration of Atlantic salmon (Salmo salar) smolts in a large hydropower reservoir

Migration rates, delay, timing, and success of acoustic-tagged Atlantic salmon (Salmo salar) presmolts (n = 120) and smolts (n = 57) are reported as they moved through the large Mactaquac Generating Station (MGS) reservoir and subsequently the lower Saint John River (SJR). The potential relationship between fish movements and the MGS operations was examined directly and via a hydrodynamic model. Migration rates were 15.4–29.3 km·day−1 within the river sections and 5.0–13.3 km·day−1 through the reservoir, a significant reduction of 32%–57%. Migratory timing was temporally mismatched with dam operations such that only a few (n = 3) smolts had the option of dam passage via spill. Migration success estimated as apparent survival was high through the reservoir (81%–100%), declined by 8%–32% during passage at the MGS, and additional losses (27%–55%) occurred during the migration to the lower SJR, such that overall survival to the estuary for the groups tagged as autumn presmolts was 61%–65%, and survival for those tagged as spring smolts was 6%–10%.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Developing environmental flow targets for benthic macroinvertebrates in large rivers using hydraulic habitat associations and taxa thresholds

Holistic environmental flows frameworks are built on our understanding of key flow-ecology relationships that support sensitive taxa and critical ecosystem functions under different flow and water level scenarios. Most research on flow-ecology relationships has typically focused on small systems, with less known about flow associations, indicator taxa, and environmental thresholds of assemblage change along hydraulic gradients of large non-wadeable rivers. We assessed benthic macroinvertebrate assemblage structure and applied Taxa Indicator Threshold ANalysis (TITAN) on biomonitoring data collected during a six-year period in the Wolastoq | Saint John River in Atlantic Canada. Flow velocity was strongly associated with the distribution and relative abundance of benthic macroinvertebrates in the river, and taxon associations reflected functional adaptations to flow. We identified 33 genus-level indicator taxa that were either positively or negatively associated with flow velocity. Weaker taxa responses were shown for the gradient in median substrate particle size where 22 negatively and positively responding taxa were identified. We predicted changes in indicator taxon abundance under different flow scenarios using a hydrodynamic model, and characterised the distribution and availability of suitable hydraulic habitat patches within a 20 km reach downstream of a large hydropower generating station. These observations set the stage for the development of ecologically-based flow targets to support holistic environmental flow management in large rivers

Critical Conversations and A Call to Action!: A collective report from the June 2020 virtual gathering

Paul Kadetz - ORCID: 0000-0002-2824-1856 https://orcid.org/0000-0002-2824-1856Critical Conversations are held by members of the greater Engineering, Social Justice, and Peace network in the activist tradition of reflecting on our public engagement and collectively discovering ways of deepening our action. The particpants are selected based on their submissions (Expressions of Interest) in response to the Call for Participation in the Critcial Conversations disseminated through the ESJP website (esjp.org). For years, we have gathered in locations immersed in nature. In 2018 and 2019, the gathering took place in Cala Munda, organized by Caroline Baillie and Eric Feinblatt, in the beautiful Catskills mountains in upstate New York in the U.S.A. We want to feel our connection with the land while we engage in critical conversations on the intersection of the engineering field with social justice and peace. Caroline Baillie facilitates these conversations employing forest pedagogy. Through this pedagogy, we open our hearts to the forest for seeking guidance on how our profession can help restore, heal, and serve people, planet, and life instead of its current practice of destroying, pillaging, and harming nature. In the throes of the coronavirus pandemic, the urgency of action was evident in 2020 like never before. On June 26 and 27, 2020, a group of up to 40 educators, researchers, activists, and field practitioners, from 4 continents, met virtually for the 4th Annual Critical Conversations – almost thrice as large as the 2018 and 2019 groups that met in-person. The virtual format allowed for broader participation – both in numbers as well as geographical locations. Though we were physically separated in the online gathering, situated in our respective modern, often disconnected-from-nature enclaves, our hearts and minds were engaged in envisioning transition to a just and egalitarian society. In keeping with the need of the moment, our focus was on brainstorming action projects that we can implement in the near future. The retreat facilitated the formation of action teams, which spent the summer discussing possible action items moving forward. These teams are now looking for a more permanent structure with team leaders, team members, an infrastructure, and social media presence. This is a call to action! We carried out these deliberations in an open-space format, wherein the agenda for the two days was set by the participants. In the two sessions on day one, using this participatory approach, we were able to sift six main themes that participants were interested in exploring in-depth. On day two, we divided ourselves into six teams and each team took a deeper dive into their theme of choice. Five of these teams have written summaries of their deliberations and proposed their Calls to Action for the engineering community, which we report below.https://doi.org/10.24908/ijesjp.v8i2.151578pubpub