SFS Annual Meeting

6/05/2024  |   10:30 - 10:45   |  Independence Ballroom B

STREAM INSECT RESPONSES TO LOWLAND STREAM AQUATIC-TERRESTRIAL ECOTONE DEGRADATION Extensive anthropogenic alterations of streams and their valleys for has rendered many of these systems morphologically and ecologically degraded. For instance, in the Netherlands, less than 5% of the streams are in near natural condition. In undisturbed streams, the aquatic-terrestrial interface can harbour a rich and diverse fauna, as well as provide numerous ecosystem services. Anthropogenic degradation of these interfaces asserts strong negative effects on stream communities. However, a lack of understanding of the underlying processes hampers the effectivity of restoration measures. A key component of these faunas are aquatic insects, their reliance on both the aquatic and terrestrial parts of the habitat, makes them uniquely suited to study both the effects of degradation and the restraints for restoration of the aquatic-terrestrial interface. Therefore, this study aimed to assess the responses of stream insects to aquatic-terrestrial ecotone degradation. To this end we monitored stream insect assemblages of nine reaches, with different levels of hydromorphological degradation, in three catchments, over 15 months. With this design, inter- and intra-catchment effects of hydromorphological degradation on the insect assemblage could be separated. Both aquatic and terrestrial stages were sampled using complementary methods and identified using DNA meta-barcoding. Species richness and functional diversity were highest in intermediate reaches, while there were large differences between the catchments. The lateral movement of adult insects in the riparian zone was limited and confined to the stream channel, with species specific abundance patterns. These results improve the understanding of degradation on stream insects guiding future restoration efforts.

Elmar Becker (Primary Presenter/Author), Institute for Biodiversity and Ecosystem Dynamics - University of Amsterdam, e.becker@uva.nl;

Arie Vonk (Co-Presenter/Co-Author), University of Amsterdam, Institute of Biodiversity and Ecosystem Dynamics, J.A.Vonk@uva.nl;

Ralf C.M. Verdonschot (Co-Presenter/Co-Author), Wageningen Environmental Research, ralf.verdonschot@wur.nl;

Michiel Kraak (Co-Presenter/Co-Author), Institute of Biodiversity and Ecosystem Dynamics, M.H.S.Kraak@uva.nl;

Piet F.M. Verdonschot (Co-Presenter/Co-Author), University of Amsterdam / Wageningen Environmental Research , piet.verdonschot@wur.nl;

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6/05/2024  |   10:45 - 11:00   |  Independence Ballroom B

Beaver Canals and Their Environmental Effects Beaver canals and their environmental effects are much less studied than beaver dams, despite being widespread in some beaver inhabited areas. In this study, we completed a systematic review of previous research on the structure and ecosystem effects of beaver canals to provide an increasingly holistic understanding of these landscape features. Specifically, we: 1) summarized why, where, when, and how beaver develop canals; 2) chronicled all published descriptions on beaver canal morphology; and 3) summarized the literature on the environmental effects of beaver canals. Thirty-one relevant studies were identified and incorporated into this review. Beaver canals have been identified in numerous environments ranging from largely undeveloped mountainous regions to heavily developed agricultural landscapes. Beaver primarily develop canals to increase accessibility to riparian resources, facilitate transport of harvested resources, and to decrease predation risk. As with beaver dams, beaver canals exhibit large structural variability, particularly in lengths, which can be over 0.5 km. Widths of about 1 m and depths of about 0.5 m are common. Beaver canals alter watershed hydrology by creating new aquatic habitats, connecting isolated aquatic features, and diverting water into colonized areas. Beaver canals have been identified as favored habitats for several biotic species and are sometimes used during critical life stages (e.g. dispersal). In addition to increasing overall floral and faunal species richness and diversity, beaver canals may benefit biota by mitigating habitat fragmentation and climate change impacts. Based on the results of this review, incorporating beaver canals into stream restoration practices may be environmentally beneficial.

Bartosz Grudzinski (Primary Presenter/Author), Miami University, grudzibp@miamioh.edu;

Hays Cummins (Co-Presenter/Co-Author), Miami University, haysc@miamioh.edu;

Teng Keng Vang (Co-Presenter/Co-Author), Miami University, vangth@miamioh.edu;

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6/05/2024  |   11:00 - 11:15   |  Independence Ballroom B

SLOW DRAWDOWN DURING THE DECOMMISSIONING OF A LARGE DAM PROMPTED FAST MACROINVERTEBRATE COMMUNITY RECOVERY Dam decommissioning has emerged as a tool for restoration efforts, addressing concerns surrounding ageing dams and their environmental impacts. While over 2000 dams have been removed globally, further research is necessary to understand the negative effects and benefits of this activity, particularly in the context of large dams. We followed a before-after/control-impact design to investigate the consequences of the decommissioning of a large dam (Enobieta Reservoir, North Spain) on invertebrate communities. Before decommissioning, we observed fine sediment starvation and high concentrations of manganese and iron below the dam. These impacts decreased with distance, reaching values similar to those measured in control sites. The dam had profound effects on the structure of macroinvertebrate communities, reducing density, taxa richness, and Shannon diversity index. The drawdown of the dam, the first step towards its decommissioning, led to erosion and downstream transport of sediments. Against our expectations, drawdown reduced the differences in macroinvertebrate communities, which showed no impact of sediments. After drawdown, the communities downstream from the dam, as well as those in the newly formed stream in the area formerly submerged by the reservoir, became very similar to those in control reaches, showing a successful restoration project. These findings emphasize the importance of dam decommissioning as a restoration strategy and highlight the positive outcomes for invertebrate communities.

Miren Atristain (Primary Presenter/Author), University of the Basque Country, miren.atristain@ehu.eus;

Libe Solagaistua (Co-Presenter/Co-Author), University of the Basque Country (UPV/EHU), libe.solagaistua@ehu.eus;

Aitor Larrañaga (Co-Presenter/Co-Author), University of the Basque Country (UPV/EHU), aitor.larranagaa@ehu.eus;

Daniel von Schiller (Co-Presenter/Co-Author), University of Barcelona, d.vonschiller@ub.edu;

Arturo Elosegi (Co-Presenter/Co-Author), University of the Basque Country (UPV/EHU), arturo.elosegi@ehu.eus;

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6/05/2024  |   11:15 - 11:30   |  Independence Ballroom B

Approaches to Securing the Nation’s Water Supply and Livelihoods through Sustainable Landscape Freshwater ecosystems Management Water is one of the limited resources in many regions of the world, and poor management of this resource has exacerbated water related challenges in the developing countries. As a water scarce country, South Africa socio-economic development and growth is intertwined with its water security status and risks. This paper is aimed at illustrating the connection and interdependencies existing between water security and the catchment activities. Special focus on the Maloti-Drakensberg water catchment area showed the impact of soil or land management on securing water resources to increase water security in South Africa. Soil erosion studies have warned about the huge amount of top soil removed and mobilized as sediments to rivers and dams or lakes. The eroded soil from upstream catchments don’t only impoverish agricultural fields (and farmers), but also reduce the water storage capacity of river’s pools, dams or lakes located downstream. Dam siltation or sedimentation contributes to dam wall’s degradation which compromise the safety of dams. The demand for water has become higher than the supply in many parts of South Africa due to the increasing population and increasing economic activities. The case studies showed that the best way to improve water security is to protect water at its source. South Africa has delineated and mapped sites that are called Strategic Water Source Areas. In addition, there are research and development projects and programmes implemented to protect these strategic water sources areas, which this paper will present.

Stanley Liphadzi (Primary Presenter/Author), Water Research Commission, STANLEYL@WRC.ORG.ZA;

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6/05/2024  |   11:30 - 11:45   |  Independence Ballroom B

The importance of hydrologic connectivity for sustaining ecosystem function in the Apalachicola River slough system The connectivity of streams that allow the flow and exchange of water, organisms, sediments, organic matter, nutrients, and energy in riverine environments is important for sustaining a wide range of ecological processes. The Apalachicola River and its floodplain and estuary are integral components of the regional hydrologic and ecological systems of the Gulf Coast. Hydrologic connectivity among the river channel, sloughs, and the surrounding floodplain is critical for the transport of nutrients, organic matter, and energy, which are necessary for ecosystem functioning. However, practices such as dredging and the creation of barriers that obstruct flow into floodplain areas during periods of low water levels are threatening this delicate balance. This research focuses on the impact of sand buildup from river management practices on two sloughs of the Apalachicola River, using field data, statistical analysis, and hydrologic modeling to assess changes in water flow and chemistry and their ecological consequences. Results of a hydrodynamic model predicted that the restoration of Spiders Cut through the removal of sand will significantly change the volume of water during low flow periods, providing water to floodplain ponds and secondary sloughs. Slough restoration projects will be a key part of the strategy to reverse the present trend. To protect the ecological health of the Apalachicola River floodplain and bay management strategies that restore flow by removing accumulated sand in the sloughs will restore this connectivity. These findings highlight the importance of restoring hydrological links to maintain the ecological health of the river and its connected ecosystems.

Love Kumar (Primary Presenter/Author), University of Florida, FL, lovekumar@ufl.edu;

Matthew Deitch (Co-Presenter/Co-Author), University of Florida, West Florida Research and Education Center, mdeitch@ufl.edu;

William K. Jones (Co-Presenter/Co-Author), Rhumbline Consultants PLLC, ken@rlconsultants.net;

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6/05/2024  |   11:45 - 12:00   |  Independence Ballroom B

DIATOM ASSEMBLAGES REVEAL NATURE-BASED SOLUTION ROLES OF WETLANDS ALONG RIVER YALA WATERSHED IN WESTERN KENYA The continued existence of freshwater ecosystems, especially rivers, is seriously threatened by watershed degradation that compromises their water quality and quantity. The situation is worsened by inadequate information on their health status, limiting the global attention needed to enhance their protection. Meanwhile, various initiatives have been proposed to restore the ecological health of riverine conditions, including natural solutions such as conserving swamps and marshes. This study assessed and determined the ecosystem health of rivers in the Yala Watershed (YW) in Kenya using the USEPA’s Biological Condition Gradient framework based on diatoms and selected water quality parameters. Thirty sampling sites were established along rivers from pristine to moderately to severely human-impacted areas. Along the rivers were swamps and marshes. Multivariate analyses were used to group sites according to water quality and indicator diatom assemblages. Sampling sites were placed along the ecological condition gradient in either high-quality sites (BCG tiers 1 and 2), moderately disturbed (tiers 3 and 4) or severely disturbed (tiers 5 to 6). All sampling sites were given a tier level or score of their ecological health and threatened status. This study found that swamps played a critical nature-based role in purifying water quality compared to riverine forests. The study stresses the crucial role of nature-based solutions played by wetlands and forests that should be enhanced, preserved, and expanded during restoration and rehabilitation actions in YW. The ecological health and threatened status scores are simple but powerful tools to inform and accelerate efforts for watershed conservation and policy change.

George Gatere Ndiritu (Primary Presenter/Author), Karatina University, Kenya, gatereg@yahoo.com;

Vernoich M. Muiruri (Co-Presenter/Co-Author), National Museums of Kenya, veronica.muiruri@yahoo.com;

Taita Terer (Co-Presenter/Co-Author), National Museums of Kenya, Nairobi, Kenya, taaita@yahoo.com;

David Courtemanch (Co-Presenter/Co-Author), The Nature Conservancy, Maine, USA, david.courtemanch@tnc.org;

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