Origins of functional connectivity in a human-modified wetland landscape

Parkos, Joseph J.; Trexler, Joel C.

doi:10.1139/cjfas-2013-0553

Cited by 14 publications

(10 citation statements)

References 61 publications

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“…This high degree of heterogeneity detected in both the native and nonnative fish assemblages points to the potential for (1) limited dispersal abilities in fish species, (2) the ability of water control structures and water management to prevent fish movement and thus increase heterogeneity, and/or (3) an overwhelming effect of the surrounding marsh characteristics and not canals per se to drive the community structure of canal fish communities. Recent work in Everglades canals comparing movement patterns between native largemouth bass and nonnative Mayan cichlids showed similar and relatively small linear movements within canals (<1 to 4 km), but did detect higher frequencies of movement over greater distances from canals into adjacent marshes in the nonnative Mayan cichlid (Parkos and Trexler ).…”

Section: Discussionmentioning

confidence: 97%

Examining gradients in ecosystem novelty: fish assemblage structure in an invaded Everglades canal system

Gandy

Rehage

2017

Ecosphere

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Citation: Gandy, D. A., and J. S. Rehage. 2017. Examining gradients in ecosystem novelty: fish assemblage structure in an invaded Everglades canal system. Ecosphere 8(1):e01634. 10. 1002/ecs2.1634 Abstract. Novel ecosystems result from a combination of altered historical abiotic regimes and new species assemblages. In freshwater systems, novel environmental conditions often result from large-scale changes to hydrological connectivity as well as species invasions. Novel environmental conditions may affect the survival of aquatic fauna by altering dispersal patterns and resource fluctuations, and/or may impose physiological constraints on native species evolutionarily adapted to particular environments. Further, novel systems can provide insight into processes driving community structure because re-sorting or filtering of regional biota is a likely consequence of decoupling from historical conditions. Although several studies document the presence of novel conditions, few examine variation or gradients in novelty. The Florida Everglades is a highly invaded and hydrologically altered system characterized by a large network of canals that compartmentalize the ecosystem and act to both increase and decrease connectivity. Little is known about how canals in this region function as habitat for native and nonnative fishes, the extent to which these canals may function as novel habitats, and how these habitat characteristics may influence distribution, abundance, and assembly patterns. In this study, we examined native and nonnative fish assemblages along a gradient of novelty, defined as the loss of wetland connectivity, influence of the natural hydrological regime, and habitat complexity (well connected to leveed canals). As novelty increased, native species richness and abundance strongly declined and the contribution of nonnatives increased to nearly 50%. Vast differences in community structure across the novelty gradient were strongly influenced by spatial factors and secondarily by hydrological factors, while habitat and abiotic factors were of very low relevance. Natives and nonnatives had opposing responses to key hydrological and habitat characteristics. Abundance of native fishes declined with decreased connectivity to adjacent marshes and canal littoral zone width, while nonnative fishes increased significantly in the most novel canals. Our results suggest that the inherent loss of natural environmental conditions and subsequent replacement by novel ones can lead to extensive changes in fish community structure. Success or failure at maintaining native assemblages will rely heavily on natural resource manager's ability to incorporate natural environmental characteristics with ecosystem restoration.

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Section: Discussionmentioning

confidence: 97%

Examining gradients in ecosystem novelty: fish assemblage structure in an invaded Everglades canal system

Gandy

Rehage

2017

Ecosphere

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“…, Kline et al. , Parkos and Trexler ). Several species, such as African jewelfish, survive the dry season by seeking refuge in solution holes and preying on native marsh fishes (Rehage et al.…”

Section: Discussionmentioning

confidence: 98%

Does a long‐term shift in Wood Stork diet foreshadow adaptability to human‐induced rapid environmental change?

Klassen

Gawlik

2018

J. Field Ornithol.

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To preserve biodiversity, identifying at‐risk populations and developing conservation plans to mitigate the effects of human‐induced rapid environmental change (HIREC) are essential. Changes in diet, especially for food‐limited species, can aid in detecting populations being impacted by HIREC, and characterizing the quality, abundance, and temporal and spatial consistency of newly consumed food items may provide insight concerning the likelihood of a species persisting in a changing environment. We used Wood Storks (Mycteria americana) nesting in the Florida Everglades as a model system to study the possible effects of HIREC on a food‐limited population. We compared the diets of Wood Storks in 2013 and 2014 with those reported during the 1970s before major anthropogenic activities affected the Everglades system and prey availability. Wood Storks in our study consumed more large‐bodied sunfish species (Lepomis spp.), fewer native marsh fishes, and more non‐native fish species than during the 1970s. Large sunfish and non‐native fish are relatively rare in the drying pools of Everglades marshes where storks traditionally forage, suggesting that Wood Storks may be using novel foraging habitats such as created wetlands (i.e., canals and stormwater ponds). Although created wetlands have long hydroperiods conducive to maintaining large‐bodied fishes and could provide alternative foraging habitat when prey availability is reduced in natural marshes, additional studies are needed to determine the extent to which these wetlands are used by Wood Storks and, importantly, the quality of prey items potentially available to foraging Wood Storks in created wetlands.

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“…). Furthermore, recent telemetry data show that Mayan cichlids inhabiting canals disperse greater distances into surrounding marshes than native fishes (>20 km from a canal in a season, Parkos and Trexler ). Thus, recovery may be slow because of the reliance on regional immigration, but it is expected at all affected sites (including the SR sites), since source populations are plentiful in the ecosystem and mobility is high for this invader.…”

Section: Discussionmentioning

confidence: 99%

Knocking back invasions: variable resistance and resilience to multiple cold spells in native vs. nonnative fishes

et al. 2016

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Extreme climate events can interact synergistically with invasions to dramatically alter ecosystem structure, function, and services. Yet, the effects of extreme climate events on species invasions remain unresolved. Extreme climate events may increase resources and decrease biotic resistance by causing physiological stress and/or mortality of native taxa, resulting in invasion opportunities for nonnative species. Alternatively, extreme climate events may regulate nonnative populations, preventing them from achieving dominance. We examined whether a sequence of three cold spells had a negative or positive effect on fish invasions in the coastal Everglades. We compared resistance (initial effects) and resilience (rate of recovery) to the cold spells between native fishes and the dominant nonnative invader, the Mayan cichlid, across eight populations expanding two mangroves drainages in the southern Everglades. We tracked native fish and nonnative Mayan cichlid populations for 10 yr including 3 yr pre‐ and 4 yr post‐cold spells. In both drainages, native fishes were more resistant to the cold spells than the nonnative species. While native fishes experienced declines at only one site, nonnative Mayan numbers were reduced by 90–100% across six sites where they were abundant pre‐disturbances. Four years after the last cold spell, we saw limited resilience in the affected nonnative populations. Only one of the six affected sites fully recovered, whereas the other five sites showed no recovery in Mayan cichlid numbers. The recovered site was closest to a canal, known to act as thermal refuges for nonnative fishes. In summary, cold spells can reduce nonnative abundances, but whether cold spells can effectively knock back invasions (and range expansions) by tropical/subtropical nonnative species will depend on how the frequency and severity of cold spells are affected by climate change. We propose that these mortality‐causing extreme events could provide rare management opportunities late in an invasion.

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Origins of functional connectivity in a human-modified wetland landscape

Cited by 14 publications

References 61 publications

Examining gradients in ecosystem novelty: fish assemblage structure in an invaded Everglades canal system

Examining gradients in ecosystem novelty: fish assemblage structure in an invaded Everglades canal system

Does a long‐term shift in Wood Stork diet foreshadow adaptability to human‐induced rapid environmental change?

Knocking back invasions: variable resistance and resilience to multiple cold spells in native vs. nonnative fishes

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