scholarly journals Shifting reef fish assemblages along a depth gradient in Pohnpei, Micronesia

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4650 ◽  
Author(s):  
Richard R. Coleman ◽  
Joshua M. Copus ◽  
Daniel M. Coffey ◽  
Robert K. Whitton ◽  
Brian W. Bowen
Keyword(s):  
Transition Zone ◽  
Reef Fish ◽  
Fish Assemblages ◽  
Depth Gradient ◽  
Central Pacific ◽  
Federated States Of Micronesia ◽  
Transition Zones ◽  
Shallow Habitat ◽  
Deep Habitat ◽  
Steep Slopes

Mesophotic coral ecosystems (MCEs) continue to be understudied, especially in island locations spread across the Indo-Pacific Ocean. Pohnpei is the largest island in the Federated States of Micronesia, with a well-developed barrier reef, and steep slopes that descend to more than 1,000 m. Here we conducted visual surveys along a depth gradient of 0 to 60 m in addition to video surveys that extend to 130 m, with 72 belt transects and 12 roving surveys using closed-circuit rebreathers, to test for changes in reef fish composition from shallow to mesophotic depths. We observed 304 fish species across 47 families with the majority confined to shallow habitat. Taxonomic and trophic positions at 30 m showed similar compositions when compared against all other depths. However, assemblages were comprised of a distinct shallow (<30 m) and deep (>30 m) group, suggesting 30 m as a transition zone between these communities. Shallow specialists had a high probability of being herbivores and deep specialists had a higher probability of being planktivores. Acanthuridae (surgeonfishes), Holocentridae (soldierfishes), and Labridae (wrasses) were associated primarily with shallow habitat, while Pomacentridae (damselfishes) and Serranidae (groupers) were associated with deep habitat. Four species may indicate Central Pacific mesophotic habitat:Chromis circumaurea, Luzonichthys seaver, Odontanthias borbonius,and an undescribed slopefish (Symphysanodon sp.). This study supports the 30 m depth profile as a transition zone between shallow and mesophotic ecosystems (consistent with accepted definitions of MCEs), with evidence of multiple transition zones below 30 m. Disturbances restricted to either region are not likely to immediately impact the other and both ecosystems should be considered separately in management of reefs near human population centers.

Biogeographical and cross-shelf patterns of reef fish assemblages in a transition zone

2010 ◽  
Vol 40 (3) ◽  
pp. 181-193 ◽  
Author(s):  
Hamish A. Malcolm ◽  
Alan Jordan ◽  
Stephen D. A. Smith
Keyword(s):  
Transition Zone ◽  
Reef Fish ◽  
Fish Assemblages

scholarly journals Spatial patterns of the structure of reef fish assemblages at a pristine atoll in the central Pacific

2010 ◽  
Vol 410 ◽  
pp. 219-231 ◽  
Author(s):  
AM Friedlander ◽  
SA Sandin ◽  
EE DeMartini ◽  
E Sala
Keyword(s):  
Reef Fish ◽  
Spatial Patterns ◽  
Fish Assemblages ◽  
Central Pacific

scholarly journals Descending to the twilight-zone: changes in coral reef fish assemblages along a depth gradient down to 65 m

2008 ◽  
Vol 371 ◽  
pp. 253-262 ◽  
Author(s):  
E Brokovich ◽  
S Einbinder ◽  
N Shashar ◽  
M Kiflawi ◽  
S Kark
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Coral Reef Fish ◽  
Fish Assemblages ◽  
Twilight Zone ◽  
Depth Gradient

scholarly journals Long-term monitoring of coral reef fish assemblages in the Western central pacific

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Adel Heenan ◽  
Ivor D. Williams ◽  
Tomoko Acoba ◽  
Annette DesRochers ◽  
Randall K. Kosaki ◽  
...  
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Coral Reef Fish ◽  
Fish Assemblages ◽  
Central Pacific ◽  
Long Term Monitoring ◽  
Term Monitoring

Spatial assemblage structure of shallow-water reef fish in Southwest Australia

2020 ◽  
Vol 649 ◽  
pp. 125-140
Author(s):  
DS Goldsworthy ◽  
BJ Saunders ◽  
JRC Parker ◽  
ES Harvey
Keyword(s):  
Shallow Water ◽  
Reef Fish ◽  
Marine Environment ◽  
Fish Assemblages ◽  
Canopy Cover ◽  
Reef Fishes ◽  
Reef Fish Assemblage ◽  
Reef Type ◽  
Present Distribution ◽  
Southwest Australia

Bioregional categorisation of the Australian marine environment is essential to conserve and manage entire ecosystems, including the biota and associated habitats. It is important that these regions are optimally positioned to effectively plan for the protection of distinct assemblages. Recent climatic variation and changes to the marine environment in Southwest Australia (SWA) have resulted in shifts in species ranges and changes to the composition of marine assemblages. The goal of this study was to determine if the current bioregionalisation of SWA accurately represents the present distribution of shallow-water reef fishes across 2000 km of its subtropical and temperate coastline. Data was collected in 2015 using diver-operated underwater stereo-video surveys from 7 regions between Port Gregory (north of Geraldton) to the east of Esperance. This study indicated that (1) the shallow-water reef fish of SWA formed 4 distinct assemblages along the coast: one Midwestern, one Central and 2 Southern Assemblages; (2) differences between these fish assemblages were primarily driven by sea surface temperature, Ecklonia radiata cover, non-E. radiata (canopy) cover, understorey algae cover, reef type and reef height; and (3) each of the 4 assemblages were characterised by a high number of short-range Australian and Western Australian endemic species. The findings from this study suggest that 4, rather than the existing 3 bioregions would more effectively capture the shallow-water reef fish assemblage patterns, with boundaries having shifted southwards likely associated with ocean warming.

scholarly journals Petiole-Lamina Transition Zone: A Functionally Crucial but Often Overlooked Leaf Trait

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 774
Author(s):  
Max Langer ◽  
Thomas Speck ◽  
Olga Speck
Keyword(s):  
Transition Zone ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Body Plan ◽  
The Body ◽  
Vascular Bundles ◽  
Cross Sectional ◽  
Thin Sections ◽  
Transition Zones ◽  
The Cross

Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans (monocotyledons vs. dicotyledons) and spatial arrangements of petiole and lamina (two-dimensional vs. three-dimensional configurations). Cross-sectional geometry and tissue arrangement of petioles and transition zones were investigated via serial thin-sections and µCT. The changes in the cross-sectional geometries from the petiole to the transition zone and the course of the vascular bundles in the transition zone apparently depend on the spatial arrangement, while the arrangement of the vascular bundles in the petioles depends on the body plan. We found an exponential acropetal increase in the cross-sectional area and axial and polar second moments of area to be the defining characteristic of all transition zones studied, regardless of body plan or spatial arrangement. In conclusion, a variety of terms is used in the literature for describing the region between petiole and lamina. We prefer the term “petiole–lamina transition zone” to underline its three-dimensional nature and the integration of multiple gradients of geometry, shape, and size.

Temporal variation of larval fish assemblages of the Murray Mouth in prolonged drought conditions

2013 ◽  
Vol 64 (10) ◽  
pp. 932 ◽  
Author(s):  
L. B. Bucater ◽  
J. P. Livore ◽  
C. J. Noell ◽  
Q. Ye
Keyword(s):  
Fish Assemblages ◽  
Larval Fish ◽  
River System ◽  
Sampling Period ◽  
Marine Species ◽  
Flow Regulation ◽  
Nursery Areas ◽  
Transition Zones ◽  
Murray Darling Basin ◽  
Drought Conditions

Estuaries are transition zones that link freshwater and marine ecosystems and are often used as nursery areas by fish. The Murray–Darling Basin, which is heavily affected by flow regulation and water extraction, is the largest river system in Australia and terminates at the Murray Mouth estuary. Protracted drought conditions resulted in extremely low flows to the Murray Mouth that affected water condition, fish abundance, community structure and fish use of the estuary (e.g. nursery areas). The aims of the present study were to examine temporal changes in larval fish assemblages in this estuary. The assemblages were dominated by two gobiid species, Arenigobius bifrenatus and Tasmanogobius lasti. There was a noticeable absence or low abundance of freshwater, diadramous and large-bodied marine species that use this estuary for reproductive functions. Monthly differences in larval fish assemblages, between August–September and October–November, were attributed to increases in the abundances of A. bifrenatus in October and November and oscillation in T. lasti during the entire sampling period. The outcomes of the present study suggested that larval fish assemblages in drought conditions are limited to small-bodied species tolerant of high salinities and that freshwater flows are needed for the estuary to function as a nursery for other species.

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