Willis, T.J.; Millar, R.B.; Babcock, R.C. 2003. Protection of exploited fishes in temperate regions: high density and biomass of snapper Pagrus auratus (Sparidae) in northern New Zealand marine reserves. Journal of Applied Ecology 40: 214–227.
Rigorous empirical evidence for the recovery of exploited species within ‘no-take’ marine reserves is limited, especially in temperate regions. The relative density and size structure of snapper Pagrus auratus: Sparidae, were measured inside and outside three northern New Zealand marine reserves using baited underwater video every six months from October 1997 to April 1999. Snapper that were larger than the minimum legal size were estimated to be 14 times denser in protected areas than in fished areas, and the relative egg production was estimated to be 18 times higher. This species was thought to be too mobile to respond to area-based protection.
02 June, 2004
Willis et al. (2000): Detection of spatial variability in relative density of fishes.
Willis, T.J.; Millar, R.B.; Babcock, R.C. 2000. Detection of spatial variability in relative density of fishes: comparison of visual census, angling, and baited underwater video. Marine Ecology Progress Series 198: 249–260.
The ability to make accurate estimates of fish relative abundance is the basis of both ecological and environmental effects studies. This paper compares surveys of snapper and blue cod conducted using three methods (underwater visual census, experimental angling, and baited underwater video). Angling and baited video gave consistent estimates of snapper density, whereas visual surveys provided the least reliable measure, with adults only detected at locations where fish have been habituated to divers by hand feeding. Blue cod, however, were well estimated using visual census. The study indicates that methodological standardisation across all species is not always appropriate for environmental effects studies.
The ability to make accurate estimates of fish relative abundance is the basis of both ecological and environmental effects studies. This paper compares surveys of snapper and blue cod conducted using three methods (underwater visual census, experimental angling, and baited underwater video). Angling and baited video gave consistent estimates of snapper density, whereas visual surveys provided the least reliable measure, with adults only detected at locations where fish have been habituated to divers by hand feeding. Blue cod, however, were well estimated using visual census. The study indicates that methodological standardisation across all species is not always appropriate for environmental effects studies.
Willis and Anderson (2003): Structure of cryptic reef fish assemblages: relationships with habitat characteristics and predator density.
Willis, T.J.; Anderson, M.J. 2003. Structure of cryptic reef fish assemblages: relationships with habitat characteristics and predator density. Marine Ecology Progress Series 257: 209–221.
The effects of reef structural complexity, kelp density, and the density of predators on assemblages of small, cryptic reef fishes were examined in northeastern New Zealand. Sampling was conducted inside and outside of a marine reserve, which acted as a high predator density treatment. There were lower densities of cryptic fishes inside the reserve, which might be explained by effects of predators. The effect of the marine reserve was strongest in the kelp forest habitat, relative to unvegetated habitats. These results imply that removal of predators by fishing may have large-scale positive effects on assemblages of small cryptic reef fishes.
The effects of reef structural complexity, kelp density, and the density of predators on assemblages of small, cryptic reef fishes were examined in northeastern New Zealand. Sampling was conducted inside and outside of a marine reserve, which acted as a high predator density treatment. There were lower densities of cryptic fishes inside the reserve, which might be explained by effects of predators. The effect of the marine reserve was strongest in the kelp forest habitat, relative to unvegetated habitats. These results imply that removal of predators by fishing may have large-scale positive effects on assemblages of small cryptic reef fishes.
Russell et al. (2004): Island biogeography and the species richness of introduced mammals on New Zealand offshore islands.
Russell, J. C.; Clout, M. N.; McArdle, B. H. 2004. Island biogeography and the species richness of introduced mammals on New Zealand offshore islands. Journal of Biogeography 31: 653–664.
Invasion of offshore islands by mammals is a constant threat to conservation in New Zealand, However the factors that correlate with the species richness of introduced mammals on New Zealand offshore islands have never been fully investigated. Using a widespread dataset these factors (geographical, ecological and anthropological) are examined. Distance appears to have become trivial in preventing invasion except for the smallest of mammals. Most high species richness appears related to human activity. Some evidence of a ‘small island’ effect is found.
Invasion of offshore islands by mammals is a constant threat to conservation in New Zealand, However the factors that correlate with the species richness of introduced mammals on New Zealand offshore islands have never been fully investigated. Using a widespread dataset these factors (geographical, ecological and anthropological) are examined. Distance appears to have become trivial in preventing invasion except for the smallest of mammals. Most high species richness appears related to human activity. Some evidence of a ‘small island’ effect is found.
Barker (2002): Gastropods as pests in New Zealand pastoral agriculture, with emphasis on Agriolimacidae, Arionidae and Milacidae.
Barker, G.M. 2002. Gastropods as pests in New Zealand pastoral agriculture, with emphasis on Agriolimacidae, Arionidae and Milacidae. Pp. 361– 423 In: Barker, G.M. (ed.) Molluscs as Crop Pests. CAB International, Wallingford.
This chapter reviews the development of agriculture in New Zealand and the emergence of introduced herbivorous gastropods as pastoral pests. In the context of an agroclimatic classiication, the link is made between environment, land use, and ecology of the gastropod communities. The pest status of Agriolimacidae, Arionidae and Milacidae is then addressed in the context of (i) established pastures, (ii) pasture establishment, (iii) forage-seed crops, and (iv) transmission of plant pathogens.
This chapter reviews the development of agriculture in New Zealand and the emergence of introduced herbivorous gastropods as pastoral pests. In the context of an agroclimatic classiication, the link is made between environment, land use, and ecology of the gastropod communities. The pest status of Agriolimacidae, Arionidae and Milacidae is then addressed in the context of (i) established pastures, (ii) pasture establishment, (iii) forage-seed crops, and (iv) transmission of plant pathogens.
Barker (2002): Phylogenetic diversity: a quantitative framework for measurement of priority and achievement in biodiversity conservation.
Barker, G.M. 2002. Phylogenetic diversity: a quantitative framework for measurement of priority and achievement in biodiversity conservation. Biological Journal of the Linnean Society 76: 165–194.
Biodiversity option value can be equated with richness of features expressed by species. Feature diversity of communities can be predicted by the phylogenetic relationships among species. The ‘Phylogenetic Diversity’ measure (PD) estimates the relative feature diversity of any nominated set of species by the patristic or path-length distances. This study reviews and expands on some of the properties of PD, and develops simple modifications of the measure to enable capture of both the phylogenetic relatedness of species and their abundances. The application of PD concepts to a range of conservation and resource management issues is demonstrated using New Zealand avian case studies.
Biodiversity option value can be equated with richness of features expressed by species. Feature diversity of communities can be predicted by the phylogenetic relationships among species. The ‘Phylogenetic Diversity’ measure (PD) estimates the relative feature diversity of any nominated set of species by the patristic or path-length distances. This study reviews and expands on some of the properties of PD, and develops simple modifications of the measure to enable capture of both the phylogenetic relatedness of species and their abundances. The application of PD concepts to a range of conservation and resource management issues is demonstrated using New Zealand avian case studies.
Barker (2001): Gastropods on land: phylogeny, diversity and adaptive morphology.
Barker, G.M. 2001. Gastropods on land: phylogeny, diversity and adaptive morphology. Pp. 1–146 In: Barker, G.M. (ed.) Biology of Terrestrial Molluscs. CAB International, Wallingford.
This chapter provides a review of the evolutionary history of gastropods, with emphasis on terrestriality achieved independently in a number of lineages and the associated morphological and ecological radiations.
This chapter provides a review of the evolutionary history of gastropods, with emphasis on terrestriality achieved independently in a number of lineages and the associated morphological and ecological radiations.
Anderson and Wilis (2003): Canonical analysis of principal coordinates: a useful method of constrained ordination for ecology.
Anderson, M.J.; Willis, T.J. 2003. Canonical analysis of principal coordinates: a useful method of constrained ordination for ecology. Ecology 84: 511–525.
We describe a new method for constrained ordination (with reference to an a priori specified hypothesis) of multivariate ecological data. Called CAP (for Canonical Analysis of Principal Coordinates), the method can use any distance or dissimilarity measure, and uses canonical tests using permutations to address hypotheses concerning correlations or differences among groups. Using reef fish data from northern New Zealand, we show how it can uncover patterns that are masked in an unconstrained ordination (such multidimensional scaling). We suggest that a CAP ordination together with an unconstrained ordination provide important information with reference to explicit a priori hypotheses concerning multivariate data.
We describe a new method for constrained ordination (with reference to an a priori specified hypothesis) of multivariate ecological data. Called CAP (for Canonical Analysis of Principal Coordinates), the method can use any distance or dissimilarity measure, and uses canonical tests using permutations to address hypotheses concerning correlations or differences among groups. Using reef fish data from northern New Zealand, we show how it can uncover patterns that are masked in an unconstrained ordination (such multidimensional scaling). We suggest that a CAP ordination together with an unconstrained ordination provide important information with reference to explicit a priori hypotheses concerning multivariate data.
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