Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item Marine reserves indirectly affect fine-scale habitat associations, but not overall densities, of small benthic fishes.(2016-09) Smith ANH; Anderson MJMany large, fishery-targeted predatory species have attained very high relative densities as a direct result of protection by no-take marine reserves. Indirect effects, via interactions with targeted species, may also occur for species that are not themselves targeted by fishing. In some temperate rocky reef ecosystems, indirect effects have caused profound changes in community structure, notably the restoration of predator-urchin-macroalgae trophic cascades. Yet, indirect effects on small benthic reef fishes remain poorly understood, perhaps because of behavioral associations with complex, refuge-providing habitats. Few, if any, studies have evaluated any potential effects of marine reserves on habitat associations in small benthic fishes. We surveyed densities of small benthic fishes, including some endemic species of triplefin (Tripterygiidae), along with fine-scale habitat features in kelp forests on rocky reefs in and around multiple marine reserves in northern New Zealand over 3 years. Bayesian generalized linear mixed models were used to evaluate evidence for (1) main effects of marine reserve protection, (2) associations with habitat gradients, including complexity, and (3) differences in habitat associations inside versus outside reserves. No evidence of overall main effects of marine reserves on species richness or densities of fishes was found. Both richness and densities showed strong associations with gradients in habitat features, particularly habitat complexity. In addition, some species exhibited reserve-by-habitat interactions, having different associations with habitat gradients inside versus outside marine reserves. Two species (Ruanoho whero and Forsterygion flavonigrum) showed stronger positive associations with habitat complexity inside reserves. These results are consistent with the presence of a behavioral risk effect, whereby prey fishes are more strongly attracted to habitats that provide refuge from predation in areas where predators are more abundant. This work highlights the importance of habitat structure and the potential for fishing to affect behavioral interactions and the interspecific dynamic attributes of community structure beyond simple predator-prey consumption and archetypal trophic cascades.Item Measures of precision for dissimilarity-based multivariate analysis of ecological communities.(2015-01) Anderson MJ; Santana-Garcon JEcological studies require key decisions regarding the appropriate size and number of sampling units. No methods currently exist to measure precision for multivariate assemblage data when dissimilarity-based analyses are intended to follow. Here, we propose a pseudo multivariate dissimilarity-based standard error (MultSE) as a useful quantity for assessing sample-size adequacy in studies of ecological communities. Based on sums of squared dissimilarities, MultSE measures variability in the position of the centroid in the space of a chosen dissimilarity measure under repeated sampling for a given sample size. We describe a novel double resampling method to quantify uncertainty in MultSE values with increasing sample size. For more complex designs, values of MultSE can be calculated from the pseudo residual mean square of a permanova model, with the double resampling done within appropriate cells in the design. R code functions for implementing these techniques, along with ecological examples, are provided.Item High functional diversity in deep-sea fish communities and increasing intraspecific trait variation with increasing latitude.(2021-08) Myers EMV; Anderson MJ; Liggins L; Harvey ES; Roberts CD; Eme DVariation in both inter- and intraspecific traits affects community dynamics, yet we know little regarding the relative importance of external environmental filters versus internal biotic interactions that shape the functional space of communities along broad-scale environmental gradients, such as latitude, elevation, or depth. We examined changes in several key aspects of functional alpha diversity for marine fishes along depth and latitude gradients by quantifying intra- and interspecific richness, dispersion, and regularity in functional trait space. We derived eight functional traits related to food acquisition and locomotion and calculated seven complementary indices of functional diversity for 144 species of marine ray-finned fishes along large-scale depth (50-1200 m) and latitudinal gradients (29°-51° S) in New Zealand waters. Traits were derived from morphological measurements taken directly from footage obtained using Baited Remote Underwater Stereo-Video systems and museum specimens. We partitioned functional variation into intra- and interspecific components for the first time using a PERMANOVA approach. We also implemented two tree-based diversity metrics in a functional distance-based context for the first time: namely, the variance in pairwise functional distance and the variance in nearest neighbor distance. Functional alpha diversity increased with increasing depth and decreased with increasing latitude. More specifically, the dispersion and mean nearest neighbor distances among species in trait space and intraspecific trait variability all increased with depth, whereas functional hypervolume (richness) was stable across depth. In contrast, functional hypervolume, dispersion, and regularity indices all decreased with increasing latitude; however, intraspecific trait variation increased with latitude, suggesting that intraspecific trait variability becomes increasingly important at higher latitudes. These results suggest that competition within and among species are key processes shaping functional multidimensional space for fishes in the deep sea. Increasing morphological dissimilarity with increasing depth may facilitate niche partitioning to promote coexistence, whereas abiotic filtering may be the dominant process structuring communities with increasing latitude.Item Hagfish feeding habits along a depth gradient inferred from stable isotopes(27/06/2013) Zintzen V; Rogers KM; Roberts CD; Stewart AL; Anderson MJFeeding habits of 3 hagfish species were investigated along a depth gradient (~50 to 900 m) in New Zealand using nitrogen (?15N) and carbon (?13C) stable isotopes. Neomyxine biniplicata had the lowest mean ?15N value (14.2%), followed by Eptatretus cirrhatus (14.9 %) and Eptatretus sp. 1 (15.8%). Neomyxine biniplicata (~50 m depth) was characterized by (1) relative low lipid content in muscles and (2) consistent body condition index which together with its trophic position indicated that this species probably acquires its food by active predation, supplemented by opportunistic scavenging. Eptatretus cirrhatus (48 to 912 m) and Eptatretus sp. 1 (290 to 922 m) had similar morphology, but their ?15N signature indicated that they were feeding on slightly different trophic levels. For Eptatretus sp. 1, the combination of (1) variable lipid content, indicating phases of feeding and fasting, (2) decreasing body condition index with depth, indicating less regular feeding at depth, (3) increasing ?15N with depth and (4) decreasing ?13C signature with depth, pointed towards a feeding behaviour specialized in scavenging on large but rare falls of high-level predators such as whales, sharks or bony fishes. On the other hand, E. cirrhatus was characterized by (1) less variable lipid content, (2) a body condition index not influenced by depth, (3) ?15N values decreasing with depth and ?13C values constant across its depth range, which is likely to indicate a more opportunistic and mobile feeding behaviour on a range of prey © 2013 Museum of New Zealand Te Papa Tongarewa and Massey University and GNS Science.