Do macrophytes act as refuges for grazing cladocera against fish predation?

Stansfield, Julia; Perrow, Martin R.; Tench, Louise D.; Jowitt, Adrian J. D.; Taylor, A. A. L.

doi:10.2166/wst.1995.0186

Cited by 3 publications

(2 citation statements)

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“…Surgeonfish leave ungrazed 'hedgerows' of algae as buffer zones between their territories (Robertson 1989). There are numerous examples from marine environments where risk of predation on a herbivore constrains the herbivore's foraging of otherwise similar habitat, thereby influencing the risk of defoliation (Randall 1965, Ogden et al 1973, Hay et al 1983, Leber 1985, Irvine et al 1990, Stachowicz and Hay 1995, Stansfield et al 1995. These tri-trophic examples generally involve use of a biotic or geologic refuge by the herbivore, and in some cases include mutualistic or facilitative relationships between the herbivore and its plant refuge.…”

Section: Indirect A6oidancesmentioning

confidence: 99%

Grazing refuges, external avoidance of herbivory and plant diversity

Milchunas¹,

Noy‐Meir²

2002

Oikos

289

245

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Avoidance and tolerance are the two means by which plants cope with herbivores. Avoidances internal to the plant, such as morphology, chemical repellants, thorns, etc., have received considerable attention in the plant‐herbivore literature, but relatively little consideration has been given to avoidances external to the plant. We develop a conceptual framework of external plant avoidances of herbivory based on foraging selection impedances (associational avoidances), behavioral impedances (indirect avoidances), and physical impedances (refuges) organized along axes of efficiency, degree of protection, and necessity of tolerance characteristics. Associational avoidances are uncommon for terrestrial mammalian herbivores compared to plant‐insect or marine situations. Indirect avoidances mediated through herbivore territoriality, predator avoidance, and other behaviors independent of foraging decisions are probably common in nature, but few have been formally documented. Biotic and geologic refuges providing a physical impedance are the only avoidances shown to have implications for plant biodiversity. This is particularly true for geologic refuges, where there is not a tradeoff between competition and the refuge effect. Small geologic refuges (rock outcrops, cliffs, etc.) are more likely to also positively or negatively alter associated plant microenvironments than large geologic refuges (mesas, islands, etc.). In a survey, 86% of small refuge studies reported positive effects on plant diversity compared to 50% for large refuges. Geologic refuges in more productive environments were more important in protecting diversity than refuges in less productive, semiarid environments, and the effects of protection were greater in communities with short compared to long evolutionary histories of grazing. Other characteristics of refuges such as extent across the landscape and the manner they alter or ameliorate the environment, as well as characteristics of the herbivore such as small or large, generalist or specialist may also determine the effectiveness of refuges, but there are too few studies to assess these factors.

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Section: Indirect A6oidancesmentioning

confidence: 99%

Grazing refuges, external avoidance of herbivory and plant diversity

Milchunas¹,

Noy‐Meir²

2002

Oikos

289

245

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“…Macrophytes have sheltering properties for zooplankton (Schriver et al, 1995) and research has shown that large Daphnia species, important for achieving low concentrations of unicellular phytoplankton, are abundant when macrophytes are present (Timms and Moss, 1984;Stansfield et al, 1995Stansfield et al, , 1997. The abundance and structure of macrophyte beds may also prove to be a key factor influencing the composition of fish populations .…”

Section: Introductionmentioning

confidence: 99%

Stable or changing lakes? a classification of aquatic macrophyte assemblages from a eutrophic shallow lake system in the United Kingdom

Kennison¹,

Dunsford²,

Schutten

1998

Aquatic Conserv: Mar. Freshw. Ecosyst.

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1. It is proposed that an appreciation of patterns of change and stability in macrophyte floras is an important tool for lake managers. 2. The presence and abundance of aquatic macrophytes was annually monitored (from 1983 to 1995) along permanent transects in 13 shallow lakes in the Broads wetland in eastern England, United Kingdom. 3. Cluster analysis (TWINSPAN) revealed three Broad Macrophyte Types (BMTs) or assemblages. Two of these were sub‐divided into four and then again into six sub‐types. BMT1 had a constant presence (i.e. in more than 60% of all samples) of charophytes, Potamogeton pectinatus L.,Myriophyllum spicatum L. and Najas marina L. BMT2 had a constant presence of Nuphar lutea (L.) Smith and filamentous algae. BMT3 consisted of sites without macrophytes. 4. The BMTs provided a useful regional classification for aquatic vegetation in shallow, calcareous, and slightly brackish lakes with relatively organic sediments. The BMTs were compared with national and international classifications. The value of BMTs as conservation targets was assessed. 5. Analysis of changes of macrophyte assemblages with time, using ordination (CANOCO) and time‐series plots, revealed lakes with stable, drifting, or erratic and unstable macrophyte assemblages. 6. The method of presentation used facilitates the interpretation of year‐to‐year macrophyte changes. The implication is that management effort can be more effectively directed towards conservation targets. The effects of management on the aquatic flora, such as dredging and biomanipulation, were shown to be easily evaluated using Cockshoot Broad as an example. © 1998 John Wiley & Sons, Ltd.

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