Summer stream habitat preferences of Nunavik anadromous Arctic char (Salvelinus alpinus) fry and parr

Arctic char is a fish species known to occupy diverse habitats within the Arctic region. However, summer habitat use during the juvenile stage of the anadromous form is largely unknown. The present study aims to characterize fry and parr summer habitat preferences. Surveys were conducted by electrofishing, associated with physical habitat characterization on several rivers of the Ungava Bay, Nunavik, Canada. At the microhabitat and station scales, fry showed significant habitat preferences for shallow water and slow velocity. At the mesohabitat scale, fry showed a significant habitat selectivity for riffles. This habitat selectivity implies that habitat models can be built to evaluate the potential of habitat suitability for Arctic char fry. However, no significant habitat selectivity was found for parr. Parr size was nonetheless positively correlated with velocity, which was found to be a limitative factor for juvenile habitat use. This first attempt at modeling juvenile anadromous Arctic char habitat in rivers emphasizes the importance of selecting an appropriate spatial scale and reiterates the fact that parr showed relatively high plasticity in stream habitat selection.

The Combined Impact of Hydropower Plants and Climate Change on River Runoff and Fish Habitats in Lowland Watersheds

Aquatic ecosystems are particularly vulnerable to anthropogenic activity and climate change. The changes in flow regimes in Lithuanian lowland rivers due to the operation of hydropower plants (HPPs) and the impact of altered flow on some fish species have already been studied. The impact of climate change on future natural river runoff and the structure of fish assemblages was also investigated. However, it is still unknown how the combined effect of climate change and flow regulation related to hydropower generation may affect fish assemblages in the downstream river reaches below the Lithuanian HPPs. In this study, the physical habitat modelling system MesoHABSIM was used to simulate spatial and temporal changes in aquatic habitats availability for different fish species under the influence of HPP at different climate change scenarios. Changes in the available habitat were assessed for common fish species in four HPP-affected rivers representing different hydrological regions of Lithuania. The modelling results showed that the operation of HPP under climate change conditions in most rivers could be beneficial for small benthic fish species such as gudgeon Gobio gobio and stone loach Barbatula barbatula. Meanwhile, for larger fish species (e.g., chub Squalius cephalus and vimba Vimba vimba) the alteration in the temporal availability of suitable habitat was relatively higher.

How and to What Degree Does Physical Structure Differ Between Natural and Artificial Habitats? A Multi-Scale Assessment in Marine Intertidal Systems

Marine infrastructures are increasing, generating a variety of impacts and introducing artificial habitats which have low ecological value and support assemblages that differ significantly from those on natural rocky coasts. While in the past there was little ecological consideration as to how artificial structures were built, now the trend is to look for “greener” designs inspired by or mimicking nature. These greening efforts have had a strong focus on enhancing physical habitat structure to support more diverse assemblages, driven by the untested assumption that artificial habitats lack the physical structure proper to natural habitats. We tested this assumption by comparing five descriptors of physical structure (inclination; exposure; roughness; abundance, and diversity of surface morphological microelements) across a combination of natural and artificial habitats of regular and irregular morphologies (seawalls = artificial regular; cliffs = natural regular; breakwaters = artificial, irregular; and boulder fields = natural irregular) in the North Adriatic Sea. Most structural descriptors were similar between artificial and natural habitats. Only inclination was consistently steeper in the artificial than in the natural habitats. Other minor differences in roughness or in the abundance of some surface microelements were related to the general morphology (regular or irregular) of the habitat rather than to its artificial or natural identity. The outcomes challenge the widespread assumption that artificial habitats lack the physical structure proper to natural habitats and stimulate renewed consideration about other structural and non-structural elements that could enhance the performance and sustainability of artificial marine structures, such as construction material, environmental setting or maintenance. They also encourage a wider reflection about what makes an artificial building surface “greener”: structural complexity is an important ecological parameter, and its deliberate increase will lead to responses in the biota, however, this may not necessarily match “more natural” conditions.

Assessing ecological patterns in Wellington south coast's nearshore rocky-reef communities for resource conservation and management

<p>Many coastal marine communities are increasingly affected by terrestrial and maritime human activities and growing coastal populations. Protection of coastal assets and the sustainable use of coastal resources requires knowledge of nearshore benthic community status; the environmental processes that structure and connect them; the quality, abundance, and distribution of physical habitat; essential habitat for species requiring protective measures, and the spatio-temporal scales at which these patterns and processes occur. To assess the status of Wellington South Coast’s (WSC) rocky-reef assemblages prior to the enactment of the Taputeranga Marine Reserve in 2009, two annual baseline surveys were conducted during the austral summers of 2007/08 and 2008/09. These surveys evaluated the biotic and abiotic components of the assemblages in terms of diversity, abundance distribution, and size-class frequency patterns of key macroalgal and mobile macro-invertebrate species. These results were analysed to develop recommendations for best post-reserve monitoring practices, including the identification of “indicator” species for rapid yet representative field surveys to assess structural and status changes. In combination with patterns described by a previous pre-reserve baseline survey series (2000) that focussed on a reduced list of macro-algal and mobile macro-invertebrate species, this final pre-reserve survey forms the basis of a historical dataset for WSC rocky reefs that can be used for long-term monitoring of ecosystem shifts due to the new reserve and to possible changes caused by anthropogenic activity or altered natural processes. These aims were addressed by collecting information directly at local/site scale and remotely, at the larger area scale. Dived baseline surveys quantified nearshore WSC rocky-reef epibenthic assemblages at 9 sites at depths ranging from 5-13.6m and at a mean distance from shore = 113m. A survey design that included three sites west of the pending marine reserve, three sites to the east, and three sites within the designated reserve was selected to permit later BACI analyses of post-reserve changes. Species surveyed were those commonly encountered during daylight on exposed surfaces and in accessible crevices and belonged to one of three epibenthic groups: macro-algae (48 species), mobile macro-invertebrates (36 species), and sessile macro-invertebrates (30 morphotypes). These surveys did not include epizoa or smaller, cryptic newly recruited macro-invertebrates. Sessile macro-invertebrate cover was only logged if >0.1%/m2. To gauge possible spatio-temporal patterns in primary productivity as a measure of ecosystem function, biomass and plant size were measured semiannually (winter, summer) for dominant kelp and fucoid species and for two key recreationally and commercially important mobile macro-invertebrate species (sea urchin and abalone). Predictive regression equations developed from wet weight and plant size can be used for future non-destructive estimates of local primary productivity and in trophic modelling. [...] This mapping data forms the basis of a legacy dataset that will assist with monitoring changes in the integrity of critical physical habitat and associated biotic cover. It has also demonstrated that representative descriptions of both biotic and abiotic benthic components can be achieved with a minimum of sampling points and by using the quicker semi-quantitative visual analysis of video. These data can also be used to ground-truth a recently-completed multi-beam acoustic survey of the area. This work has used the approach of landscape ecology, which explains patterns in community structure, function, status and biophysical causes from a spatial perspective, to study biophysical patterns in WSC epibenthic rocky-reef communities. The work identified a high degree of spatial and temporal variation within the abiotic and biotic community within and outside of the reserve area and the limited availability of preferred habitat. The work also identified the need to include indicator species in monitoring to improve the chance of detecting impacted assemblages. These results, and the development of non-destructive sampling tools for assessing ecosystem status, are relevant locally and nationally for resource managers.</p>

Assessing ecological patterns in Wellington south coast's nearshore rocky-reef communities for resource conservation and management

<p>Many coastal marine communities are increasingly affected by terrestrial and maritime human activities and growing coastal populations. Protection of coastal assets and the sustainable use of coastal resources requires knowledge of nearshore benthic community status; the environmental processes that structure and connect them; the quality, abundance, and distribution of physical habitat; essential habitat for species requiring protective measures, and the spatio-temporal scales at which these patterns and processes occur. To assess the status of Wellington South Coast’s (WSC) rocky-reef assemblages prior to the enactment of the Taputeranga Marine Reserve in 2009, two annual baseline surveys were conducted during the austral summers of 2007/08 and 2008/09. These surveys evaluated the biotic and abiotic components of the assemblages in terms of diversity, abundance distribution, and size-class frequency patterns of key macroalgal and mobile macro-invertebrate species. These results were analysed to develop recommendations for best post-reserve monitoring practices, including the identification of “indicator” species for rapid yet representative field surveys to assess structural and status changes. In combination with patterns described by a previous pre-reserve baseline survey series (2000) that focussed on a reduced list of macro-algal and mobile macro-invertebrate species, this final pre-reserve survey forms the basis of a historical dataset for WSC rocky reefs that can be used for long-term monitoring of ecosystem shifts due to the new reserve and to possible changes caused by anthropogenic activity or altered natural processes. These aims were addressed by collecting information directly at local/site scale and remotely, at the larger area scale. Dived baseline surveys quantified nearshore WSC rocky-reef epibenthic assemblages at 9 sites at depths ranging from 5-13.6m and at a mean distance from shore = 113m. A survey design that included three sites west of the pending marine reserve, three sites to the east, and three sites within the designated reserve was selected to permit later BACI analyses of post-reserve changes. Species surveyed were those commonly encountered during daylight on exposed surfaces and in accessible crevices and belonged to one of three epibenthic groups: macro-algae (48 species), mobile macro-invertebrates (36 species), and sessile macro-invertebrates (30 morphotypes). These surveys did not include epizoa or smaller, cryptic newly recruited macro-invertebrates. Sessile macro-invertebrate cover was only logged if >0.1%/m2. To gauge possible spatio-temporal patterns in primary productivity as a measure of ecosystem function, biomass and plant size were measured semiannually (winter, summer) for dominant kelp and fucoid species and for two key recreationally and commercially important mobile macro-invertebrate species (sea urchin and abalone). Predictive regression equations developed from wet weight and plant size can be used for future non-destructive estimates of local primary productivity and in trophic modelling. [...] This mapping data forms the basis of a legacy dataset that will assist with monitoring changes in the integrity of critical physical habitat and associated biotic cover. It has also demonstrated that representative descriptions of both biotic and abiotic benthic components can be achieved with a minimum of sampling points and by using the quicker semi-quantitative visual analysis of video. These data can also be used to ground-truth a recently-completed multi-beam acoustic survey of the area. This work has used the approach of landscape ecology, which explains patterns in community structure, function, status and biophysical causes from a spatial perspective, to study biophysical patterns in WSC epibenthic rocky-reef communities. The work identified a high degree of spatial and temporal variation within the abiotic and biotic community within and outside of the reserve area and the limited availability of preferred habitat. The work also identified the need to include indicator species in monitoring to improve the chance of detecting impacted assemblages. These results, and the development of non-destructive sampling tools for assessing ecosystem status, are relevant locally and nationally for resource managers.</p>

Environmental flow assessment in the context of climate change: a case study in Southern Quebec (Canada)

Through a case study in Southern Quebec (Canada), the assessment of environmental flows in light of the effects of climate change is investigated. Currently, the 7Q2 flow metric (7-day average flow with a 2-year return period) is used for water abstraction management. Several flow metrics were calculated using flow time series simulated by a deterministic hydrological model (HYDROTEL) and climate change scenarios as inputs. Results were compared within homogeneous low flow regions defined using ascendant hierarchical clustering, for the 1990, 2020 and 2050 horizons and annual, summer and winter periods. The impact of each flow metric on the potential availability of physical habitat was analyzed using the wetted perimeter as a proxy. Results indicated that: (1) the increasing non-stationarity of simulated flow data sets over time will complicate the use of frequency analysis to calculate the 7Q2 flow metric; (2) summer low flow values are expected to be lower than winter low flows; and (3) flow-duration curve metrics like the LQ50 (median discharge value of the month with the lowest flow) may become relevant environmental flow metrics by 2050. Results question current water abstraction management tools and permit to anticipate future local and regional issues during low flow periods.

An ecohydraulic-based expert system for optimal management of environmental flow at the downstream of reservoirs

Linking ecohydraulic modeling and reservoir operation optimization is a requirement for robust management of the environmental degradations at the downstream of the reservoirs. The present study proposes and evaluates an ecohydraulic-based expert system to optimize environmental flow at the downstream of the reservoirs. Three fuzzy inference systems including physical habitat assessment, water quality assessment and combined suitability assessment were developed based on the expert panel method. Moreover, water temperature and dissolved oxygen were simulated by the coupled particle swarm optimization (PSO)–adaptive neuro-fuzzy inference system. Three evolutionary algorithms including PSO, differential evolution algorithm (DE) and biogeography-based optimization were applied to optimize the environmental flow regime. A fuzzy technique for order of preference by similarity to ideal solution was applied to select the best evolutionary algorithm to assess environmental flow. Based on the results in the case study, the proposed method provides a robust framework for simultaneous management of environmental flow and water supply. DE was selected as the best algorithm to optimize environmental flow. The optimization system was able to balance habitat losses, storage loss and water supply loss that might reduce negotiations between the stakeholders and environmental managers in the reservoir management.

Marbled Murrelets prefer stratified waters close to freshwater inputs in Haida Gwaii, British Columbia, Canada

The Marbled Murrelet (Brachyramphus marmoratus) is a small seabird that is currently listed as threatened in Canada. Understanding this species’ marine habitat preferences plays a vital role in our ability to focus conservation planning. We used the longest-running at-sea survey dataset available in British Columbia to examine hotspot persistence and habitat use at Laskeek Bay, Haida Gwaii, BC. The Laskeek Bay Conservation Society has been conducting spring and summer surveys along fixed transect routes in open and shoreline waters from 1997 to 2018. Along with analyzing this long-term dataset, we conducted surveys to measure oceanographic variables (2018–2019) and tested whether Marbled Murrelets in the same area used prey and oceanographic information to select marine habitat in conjunction with physical habitat features. Our hotspot persistence map, defined as areas that repeatedly had counts above a 75% threshold relative to other areas during a given survey, showed that murrelets consistently preferred shoreline transects. Murrelets also preferred shallow marine areas closer to streams, above higher proportions of sandy substrate and closer proximity to abundant nesting habitat. Modeling weather and time variables contributed little additional predictive power. Nonetheless, models that included physical environmental, oceanographic, and prey variables outperformed those with only physical environmental variables. Stratified water was the oceanographic variable most strongly related to higher counts. Our study suggests that stratified waters could work with stream systems to create productive zones for foraging murrelets, and highlights the importance of murrelets having access to marine areas with the preferred physical features.

Environmental quality assessment in Central Andean rivers: using the Ecological Thresholds Concept, Environmental Quality Standards, and Biotic Indexes

As in many other countries, Peru has the Water Quality Standard (WQS) as the primary tool for managing and diagnosing water resources. An analysis variable by variable to define water quality as poor or good was applied by setting concentration limits. A second group of tools commonly used are Biotic Indexes based on tolerance of benthic macroinvertebrates to pollution, that reflect the impacts caused by a group of variables, even though they cannot identify which variables determine the viability of the ecosystem. This research proposes to include the Stable States approach to evaluate the ecological integrity in central Andes rivers to explore an alternative approach with the capacity to represent a broader number of factors through multivariate analysis. A ten-year database of biological and physical-chemical variables measured in five Andean rivers were evaluated. Our results suggest these rivers fluctuate into two seasonal stable states (wet and dry season), accounting for approximately 31% of the system variability. In the wet season, the equilibrium of the state was dominated by the highest levels of suspended solids, turbidity, coliform, phosphorus, and some metals. During the dry season, the key variables were dissolved oxygen, flow, physical habitat, and biotic and diversity indexes. Likewise, there seems to be a third alternative state influenced by human pressures because of variables that exceed the WQS. Regarding water quality, the concentrations of coliforms, phosphorus, and lead usually exceeded the limits in two stations, but not every year. The ecological condition was better represented by ABI index than EPT.