Effects of streamflow reductions on aquatic macroinvertebrates: linking groundwater withdrawals and assemblage response in southern New Jersey streams, USA

Abstract

A comprehensive hydro-ecological investigation was conducted to determine the ecological response of increased groundwater withdrawals from the Kirkwood-Cohansey aquifer system, an important source of water supply in southern New Jersey, USA. Collocated observations were made of aquatic-macroinvertebrate assemblages and stream hydrologic attributes to develop flow-ecology response relations. A sub-regional transient groundwater flow model (MODFLOW) was used to simulate three plausible high-stress groundwater-withdrawal scenarios which resulted in stream baseflow reductions of approximately 0.12, 0.20, and 0.26 m 3 s -1 . These reduction scenarios were used to construct flow-alteration ecological response models to evaluate aquaticmacroinvertebrate response to streamflow reduction. For example, flow-alteration ecological response models indicate that if groundwater withdrawals diminish mean annual streamflow from 1.1 to 0.6 m 3 s -1 , the abundance of intolerant taxa could be reduced by as much as 20%. These flow-alteration ecological response modelling results could be used by resource professionals to evaluate alternative water management strategies to determine maximum basin withdrawal rates that meet ongoing human water demand while protecting biological integrity.Key words hydro-ecology; streamflow alteration; aquatic macroinvertebrates; flow-ecology relations; groundwater model; MODFLOW; withdrawal scenarios Effets de la réduction des débits sur les macro-invertébrés aquatiques: relier les prélèvements d'eaux souterraines et la réponse des communautés dans les cours d'eaux du Sud du New Jersey, Etats-Unis Résumé Une enquête hydro-écologique globale a été menée pour déterminer la réponse écologique de l'augmentation des prélèvements d'eau souterraine de l'aquifère Kirkwood-Cohansey, une importante source d'approvisionnement en eau du Sud du New Jersey, Etats-Unis. Des observations co-localisées de communautés de macro-invertébrés aquatiques et d'attributs hydrologiques des cours d'eau ont été réalisées pour établir les relations de la réponse débit-écologie. Un modèle sous-régional transitoire de l'écoulement des eaux souterraines (MODFLOW) a été utilisé pour simuler trois scénarios plausibles de prélèvements importants des eaux souterraines qui ont abouti à une réduction du débit de base des cours d'eau de l'ordre de 0,12, 0,20 et 0,26 m3/s. Ces scénarios de réduction ont été utilisés pour élaborer des modèles de réponse écologique à l'altération du débit, pour évaluer la réponse des macro-invertébrés aquatiques à la réduction des débits. Par exemple, les modèles de réponse écologique à l'altération du débit indiquent que si les prélèvements d'eaux souterraines provoquent la diminution de l'écoulement annuel moyen de 1,1 m3/s à 0,6 m3/s, l'abondance des taxons intolérants pourrait être réduite de près de 20%. Ces résultats de la modélisation de la réponse écologique pourraient être utilisés par les professionnels des ressources pour évaluer des stratégies alternatives de gestion de l'eau afin de dé...

Macroinvertebrate responses to flow and stream temperature variability across regulated and non‐regulated rivers

“…A number of studies have explored ecosystem responses to a suite of flow indices based around the five facets of the natural flow regime (e.g., Monk et al, ; Belmar et al, ; Kennen et al, ). While there is increasing recognition that fluvial ecosystems respond to comparable forms of stream temperature variability (Olden & Naiman, ), few studies have explored the ecological implications of this, and even less have examined biotic responses to flow and stream temperature variability together (a notable exception being Jackson et al, ).…”

“…Such frameworks have underpinned the identification and examination of over 200 "ecologically relevant" flow indices (Olden & Poff, 2003;Monk, Wood, Hannah, & Wilson, 2007) that have been related to ecological responses in lotic environments across a wide range of studies (e.g., Englund & Malmqvist, 1996;Clausen & Biggs, 1997;Monk et al, 2006;Kennen, Riva-Murray, & Beaulieu, 2010;Belmar et al, 2013;Worrall et al, 2014). Such ecohydrological relationships have also been established to quantify the biotic alterations driven by different forms of hydrological modification, including river impoundments (Armanini et al, 2014) and groundwater abstraction (Kennen, Riskin, & Charles, 2014).…”

Habitat‐specific invertebrate responses to hydrological variability, anthropogenic flow alterations, and hydraulic conditions

“…However, land use changes (Chadwick et al., ; López‐Moreno et al., ) and water resource management practices have profoundly altered river flow regimes (De Graaf, Van Beek, Wada, & Bierkens, ; Gleeson & Richter, ; Lehner et al., ), significantly threatening the integrity of lotic ecosystems globally (Bunn & Arthington, ; Poff et al., ; Vörösmarty et al., ). For example, groundwater abstraction substantially reduces river discharges worldwide (De Graaf et al., ) and profoundly alters lotic ecosystems (Bradley, Streetly, Farren, Cadman, & Banham, ; Bradley et al., ; Kennen, Riskin, & Charles, ). Conversely, some management activities elevate river discharges (e.g.…”

The changing role of ecohydrological science in guiding environmental flows

“…Aldous and Bach (2014) found that, for fens in Oregon, USA, water table depth is the critical issue rather than river flow, with a required water table within 35 cm of the surface. Hendriks et al (2014) reported that drainage and groundwater abstraction in sandy catchments in the Netherlands meant that low flows were reduced below the environmental flow criterion, whilst Kennen et al (2014) found that groundwater abstraction led to a 20% reduction in intolerant macro-invertebrates in New Jersey, USA, due to reduced river flow. Streetly et al (2014), working in the midlands of England, also found that flow reductions caused by The changing role of ecohydrological science in guiding environmental flowsgroundwater abstraction altered ecological conditions (as measured by relevant biotic indices).…”

“…The science of environmental flows has also benefited from closer links with other aspects of hydrological science. For example, groundwater modelling assists with understanding groundwater-fed ecosystems (Kennen et al 2014, Streetly et al 2014 including those in permeable sandy substrata (Hendriks et al 2014).…”