Browsing by Author "Zintzen V"

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    Diversity and composition of demersal fishes along a depth gradient assessed by baited remote underwater stereo-video.
    (2012) Zintzen V; Anderson MJ; Roberts CD; Harvey ES; Stewart AL; Struthers CD
    BACKGROUND: Continental slopes are among the steepest environmental gradients on earth. However, they still lack finer quantification and characterisation of their faunal diversity patterns for many parts of the world. METHODOLOGY/PRINCIPAL FINDINGS: Changes in fish community structure and diversity along a depth gradient from 50 to 1200 m were studied from replicated stereo baited remote underwater video deployments within each of seven depth zones at three locations in north-eastern New Zealand. Strong, but gradual turnover in the identities of species and community structure was observed with increasing depth. Species richness peaked in shallow depths, followed by a decrease beyond 100 m to a stable average value from 700 to 1200 m. Evenness increased to 700 m depth, followed by a decrease to 1200 m. Average taxonomic distinctness △(+) response was unimodal with a peak at 300 m. The variation in taxonomic distinctness Λ(+) first decreased sharply from 50 to 300 m, then increased beyond 500 m depth, indicating that species from deep samples belonged to more distant taxonomic groups than those from shallow samples. Fishes with northern distributions progressively decreased in their proportional representation with depth whereas those with widespread distributions increased. CONCLUSIONS/SIGNIFICANCE: This study provides the first characterization of diversity patterns for bait-attracted fish species on continental slopes in New Zealand and is an imperative primary step towards development of explanatory and predictive ecological models, as well as being fundamental for the implementation of efficient management and conservation strategies for fishery resources.
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    Effects of latitude and depth on the beta diversity of New Zealand fish communities.
    (14/08/2017) Zintzen V; Anderson MJ; Roberts CD; Harvey ES; Stewart AL
    Marine ecosystems are difficult to sample quantitatively at increasing depth. Hence, few studies attempt to measure patterns of beta diversity for ecological communities in the deep sea. Here we (i) present and quantify large-scale gradients in fish community structure along depth and latitude gradients of the New Zealand EEZ, (ii) obtain rigorous quantitative estimates of these depth (50-1200 m) and latitudinal effects (29.15-50.91°S) and their interaction, and (iii) explicitly model how latitudinal beta diversity of fishes varies with depth. The sampling design was highly structured, replicated and stratified for latitude and depth, using data obtained from 345 standardised baited remote underwater stereo-video deployments. Results showed that gradients in fish community structure along depth and latitude were strong and interactive in New Zealand waters; latitudinal variation in fish communities progressively decreased with depth following an exponential decay (r 2 = 0.96), revealing increasingly similar fish communities with increasing depth. In contrast, variation in fish community structure along the depth gradient was of a similar magnitude across all of the latitudes investigated here. We conclude that an exponential decay in beta diversity vs depth exists for fish communities present in areas shallower than the New Zealand upper continental slope.
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    Hagfish feeding habits along a depth gradient inferred from stable isotopes
    (27/06/2013) Zintzen V; Rogers KM; Roberts CD; Stewart AL; Anderson MJ
    Feeding 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.