Impacts of an introduced predatory fish on mayfly grazing in New Zealand streams

McIntosh, Angus R.; Townsend, Colin R.

doi:10.4319/lo.1995.40.8.1508

Cited by 43 publications

(28 citation statements)

References 17 publications

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“…Thus, our stable isotope data indicate that Deleatidium at trout sites assimilated greater proportions of algal carbon than at notrout sites, even though Deleatidium larvae in trout streams avoid the upper surfaces of stones during the day, resulting in lower individual algal consumption rates (McIntosh and Townsend 1995). Mayflies including Deleatidium grow better on algae than detritus (Gupta et al 1993;Ledger and Winterbourn 2000), and it is likely that Deleatidium derives most of its energy from epilithic algae when they are abundant.…”

Section: Discussionmentioning

confidence: 93%

Top-down and bottom-up processes in grassland and forested streams

2003

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The influence of predatory fish on the structure of stream food webs may be altered by the presence of forest canopy cover, and consequent differences in allochthonous inputs and primary production. Eight sites containing introduced brown trout ( Salmo trutta) and eight sites that did not were sampled in the Cass region, South Island, New Zealand. For each predator category, half the sites were located in southern beech (Nothofagus) forest patches (range of canopy cover, 65-90%) and the other half were in tussock grassland. Food resources used by two dominant herbivores-detritivores were assessed using stable isotopes. (13)C/(12)C ratios were obtained for coarse particulate organic matter (CPOM), fine particulate organic matter (FPOM), algal dominated biofilm from rocks, and larvae of Deleatidium (Ephemeroptera) and Olinga (Trichoptera). Total abundance and biomass of macroinvertebrates did not differ between streams with and without trout, but were significantly higher at grassland sites than forested sites. However, taxon richness and species composition differed substantially between trout and no-trout sites, irrespective of whether streams were located in forest or not. Trout streams typically contained more taxa, had low biomass of predatory invertebrates and large shredders, but a high proportion of consumers with cases or shells. The standing stock of CPOM was higher at forested sites, but there was less FPOM and more algae at sites with trout, regardless of the presence or absence of forest cover. The stable carbon isotope range for biofilm on rocks was broad and encompassed the narrow CPOM and FPOM ranges. At trout sites, carbon isotope ratios of Deleatidium, the most abundant invertebrate primary consumer, were closely related to biofilm values, but no relationship was found at no-trout sites where algal biomass was much lower. These results support a role for both bottom-up and top-down processes in controlling the structure of the stream communities studied, but indicate that predatory fish and forest cover had largely independent effects.

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Section: Discussionmentioning

confidence: 93%

Top-down and bottom-up processes in grassland and forested streams

2003

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“…Mayfly nymphs fed significantly more during the night in streams with introduced brown trout than in streams with native galaxias, a difference that reflects the diel variation in predation risk imposed by the fish (McIntosh & Townsend 1995).…”

Section: Temporal Shifts Of Predators and Their Preymentioning

confidence: 99%

“…In New Zealand, native common river galaxias (Galaxias vulgaris) were replaced in many streams by introduced brown trout (McIntosh & Townsend 1995) that present a higher predation risk to Deleatidium mayfly nymphs during the day than at night, while common river galaxias present a similar risk throughout the diel cycle. Mayfly nymphs fed significantly more during the night in streams with introduced brown trout than in streams with native galaxias, a difference that reflects the diel variation in predation risk imposed by the fish (McIntosh & Townsend 1995).…”

Section: Temporal Shifts Of Predators and Their Preymentioning

confidence: 99%

Partitioning of Time as an Ecological Resource

Kronfeld‐Schor

Dayan

2003

Annu. Rev. Ecol. Evol. Syst.

784

684

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s Abstract Animal species have evolved different diel activity rhythms that are of adaptive value. Theory suggests that diel temporal partitioning may facilitate coexistence between competitors and between predators and prey. However, relatively few studies demonstrate a temporal shift that is predation-or competition-induced. Recorded shifts are usually within the preferred activity phase of animal species (day or night), although there are some inversions to the opposite phase cycle. Temporal partitioning is not perceived as a common mechanism of coexistence. This rarity has been variously ascribed to theoretical considerations and to the rigidity of time-keeping mechanisms, as well as to other physiological and anatomical traits that may constrain activity patterns. Our decade-long study of spiny mice of rocky deserts demonstrates that, while different factors select for activity patterns, endogenous rhythmicity may be an evolutionary constraint.

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“…(Fig. 9) Galaxias vulgaris: Townsend & Crowl 1991: 347;McDowall & Allibone 1994: 163;Mclntosh & Townsend 1995a: 18211995b: 1508(aW partim: non G. vulgaris Stokell 1949. Also usually has no pyloric caeca (exceptionally 1 or 2 short caeca), as against 2 (rarely 3) long caeca in others of the G. vulgaris-gmup (see Fig.…”

Section: Fig 7 Shape Of Jaw Profile In Ventral View Of (A) As In Galmentioning

confidence: 99%

Two further new species ofGalaxias(Teleostei: Galaxiidae) from the Taieri River, southern New Zealand

McDowall

1997

Journal of the Royal Society of New Zealand

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Two new species of Galaxias have overlapping distributions in the lower Taieri River catchment, Otago, although not as yet found in sympatry. Galaxias pullus n.sp. is known from several tributaries of the Waipori River up-and downstream of Lake Mahinerangi, and also from a tributary of the Waitahuna, part of the Clutha River catchment. Galaxias eldoni n.sp. comes from several small tributaries of the lower Taieri near Outram and Middlemarch, from a tributary of the Waipori River below Lake Mahinerangi, from a tributary of the lake, and also a west branch tributary of the Tokomairiro River. These new species belong within the Galaxias vulgaris speciesgroup, which otherwise includes the nominate species, G. anomalus and G. depressiceps. Most populations of this species-group south of the Waitaki River are not G. vulgaris (sensu stricto), but belong to one of four other species now recognised from the region. The known distributions probably reflect a combination of incomplete knowledge and fragmentation of ranges resulting from the effects of introduced species.

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Impacts of an introduced predatory fish on mayfly grazing in New Zealand streams

Cited by 43 publications

References 17 publications

Top-down and bottom-up processes in grassland and forested streams

Top-down and bottom-up processes in grassland and forested streams

Partitioning of Time as an Ecological Resource

Two further new species ofGalaxias(Teleostei: Galaxiidae) from the Taieri River, southern New Zealand

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