Experimental analysis of recruitment patterns of coral reef fishes in seagrass beds: Effects of substrate type, shape, and rigidity     

Yohei Nakamura  Hiroyuki Kawasaki  Mitsuhiko Sano 《Estuarine, Coastal and Shelf Science》2007,71(3-4):559-568

Habitat choice of reef fish larvae at settlement is one of the mechanisms proposed to explain spatial patterns in the distribution of fishes and the corresponding spatial structure of communities. Field experiments using Pomacentridae were conducted at Iriomote Island, southern Japan, in order to determine if rare recruitment of coral reef fishes in seagrass beds is due to larval settlement preference. When three types of natural patch treatments (branching coral patch, seagrass patch, and control without patches) were established in cleared seagrass squares in the center of a seagrass bed, four pomacentrid species, Amblyglyphidodon curacao, Dischistodus prosopotaenia, Cheiloprion labiatus, and Dascyllus aruanus, recruited exclusively onto the coral patches, indicating that larvae distributed in the seagrass bed may have preferred a coral rather than seagrass substrate as a settlement habitat. The effects of differences in physical shape (grid structure for branching coral vs. vertical structure for seagrass leaves) and rigidity (rigid substrate for coral vs. flexible substrate for seagrass) between coral and seagrass substrates on such recruitment patterns were investigated using artificial coral and seagrass units. When artificial habitat units with predator exclusion cages were established in the cleared seagrass squares as above, high densities of A. curacao and D. prosopotaenia recruits were observed on the rigid rather than flexible habitat units (both unit types having similar shape), whereas differences in recruit numbers of the two species were unclear in differently shaped units. These results demonstrated that even though pomacentrid larvae are distributed in the seagrass bed, they do not settle on the seagrass substrate owing to their habitat choice being partially based on a preference for substrate rigidity. Moreover, non-recruitment of C. labiatus and D. aruanus on artificial habitat units suggested that the presence of living coral substrates rather than physical shape/rigidity of substrates are an important cue for habitat choice of these fishes.  相似文献   

Host‐dependent differences in resource use associated with Anilocra spp. parasitism in two coral reef fishes,as revealed by stable carbon and nitrogen isotope analyses          下载免费PDF全文

Rachel L. Welicky  Amanda W. J. Demopoulos  Paul C. Sikkel 《Marine Ecology》2017,38(2)

The role of parasites in trophic ecology is poorly understood in marine ecosystems. Stable isotope analyses (SIA) have been widely used in studies of trophic ecology, but have rarely been applied to study the role of parasites. Considering that some parasites are associated with altered host foraging patterns, SIA can help elucidate whether parasitism influences host trophic interactions. French grunt (Haemulon flavolineatum), an abundant Caribbean coral reef fish, contributes greatly to trophic connectivity. They typically depart the reef at dusk, feed overnight in seagrass beds, and return to the reef at dawn. The large parasitic isopod Anilocra haemuli commonly infects French grunt, and infected fish are less likely to complete their diel migration, and are in poorer condition than uninfected conspecifics. Brown chromis (Chromis multilineata) are diurnally feeding planktivores and infection by Anilocra chromis does not influence host condition. To determine if Anilocra infection influences host diet and foraging locality, we conducted stable carbon and nitrogen isotope analyses on scale, muscle, heart and gill tissues of infected and uninfected French grunt and brown chromis. We determined that all French grunt had δ¹³C values representative of seagrass habitats, but infected French grunt were significantly enriched in ¹³C and ¹⁵N compared to uninfected conspecifics. This suggests that compared to uninfected conspecifics, infected French grunt forage in seagrass, but on isotopically enriched prey, and/or are in poorer condition, which can elevate δ¹³C and δ¹⁵N values. For brown chromis, infection did not significantly influence any δ¹³C and δ¹⁵N values; hence they all foraged in the same environment and on similar prey. This is the first study to use SIA to examine differences in resource use by Caribbean coral reef fishes associated with parasitism and to evaluate how closely related parasites might have host‐dependent effects on host trophic ecology.  相似文献   

Rates of coastal erosion and accretion in New Zealand     

Jeremy G. Gibb 《新西兰海洋与淡水研究杂志》2013,47(4):429-456

Abstract

Rates of coastal erosion and accretion for New Zealand are calculated for the period since early European colonisation. Methods used for calculating rates from cadastral plans, vertical aerial photographs and field measurements are described, evaluated, and illustrated with examples. The most natural reference line for measurements of shoreline changes and for defining the seaward boundary of land is the seaward limit of land vegetation. Measurements made from air photographs and plans at scales larger than 1:4000 have errors less than ± 1 m. As scales become small, errors increase proportionately. Along depositional shorelines, erosion and accretion generally occur at 0.5–4.0 m.y^?1. Maximum erosion and accretion rates are 25.4 m.y^?1 at North Kaipara Head and 68.9 m.y^?1 at Farewell Spit respectively. Cliff recession generally occurs at 0.25 ‐ 1.0 m.y^?1 with maximum rates of 2.25 m.y^?1 for mudstone cliffs at Cape Tumagain and 3.46 m.y^?1 for conglomerate cliffs at Ngapotiki.  相似文献   

Foreign barnacles transported to New Zealand on an oil platform     

B. A. Foster  R. C. Willan 《新西兰海洋与淡水研究杂志》2013,47(1):143-149

Twelve species of barnacles were identified from the fouling community on the parts of the ‘Maui’ oil platform that were submerged during its tow from Japan in 1975 and after its arrival in New Zealand. The stalked barnacles Lepas anatifera L. var. (a) Darwin, L. anserifera L., Conchoderma auritum (L.), and C. virgatum (Spengler) probably settled during the tow across the tropical Pacific, and have been recorded in New Zealand waters before from ships (the Lepas spp.) and vertebrates (the Conchoderma spp.). The acorn barnacles were small, and probably settled in Japanese waters; Balanus variegatus Darwin and B. amphitrite Darwin already occur in northern New Zealand waters. The other six species—B. improvisus Darwin, B. albicostatus Pilsbry, B. reticulatus Utinomi, Megabalanus volcano (Pilsbry), M. rosa (Pilsbry), and Tetraclita squamosa japonica Pilsbry—have not been recorded from New Zealand before.  相似文献