Willem Renema - Academia.edu (original) (raw)
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Centre National de la Recherche Scientifique / French National Centre for Scientific Research
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Papers by Willem Renema
Ecology, Jan 1, 2010
Reef ecosystems built during successive periods of Pleistocene sea level rise have shown remarkab... more Reef ecosystems built during successive periods of Pleistocene sea level rise have shown remarkable persistence in coral community structure, but little is known of the ecological characteristics of reef communities during periods of low sea stands or sea level falls. We sampled the relative species abundance of coral, benthic foraminifera, and calcareous red algae communities from eight submerged coral reefs in the Huon Gulf, Papua New Guinea, which formed during successive sea level fall and lowstand periods over the past ;416 kyr. We found that dissimilarity in coral species composition increased significantly with increasing time between reef-building events. However, neither coral diversity nor the taxonomic composition of benthic foraminifera and calcareous red algae assemblages varied significantly over time. The taxonomic composition of coral communities from lowstand reefs was significantly different from that of highstand reefs previously reported from the nearby Huon Peninsula. We interpret the community composition and temporal dynamics of lowstand reefs as a result of shifting energy regimes in the Huon Gulf, and differences between low and highstand reefs as a result of differences in the interaction between biotic and environmental factors between the Huon Gulf and Huon Peninsula. Regardless of the exact processes driving these trends, our study represents the first glimpse into the ecological dynamics of coral reefs during low sea level stands when climatic conditions for reef growth were much different and less optimal than during previously studied highstand periods.
This study is a preliminary assessment of an extremely diverse Tortonian (late Miocene) mollusk a... more This study is a preliminary assessment of an extremely diverse Tortonian (late Miocene) mollusk assemblage from a coral carpet environment preserved at Bontang (East Kalimantan, Indonesia). Even though coral-associated aragonitic faunas are rarely well preserved, the composition of the assemblage described here can be used to address the following questions: (1) How do the mollusk assemblages in coral habitats differ from other habitats, and What is the effect of sampling on estimates of taxon richness? The mollusk assemblage is dominated by predatory snails and includes typical modern coralassociated taxa such as the gastropod Coralliophila and the bivalve Tridacna. Our investigation implies that adequate documentation of Cenozoic mollusk diversity in the Indo-Pacific is even more challenging than previously expected as very large samples are required to capture species richness. Further assessments of fossil faunas from coral-dominated habitats will be required to provide insight to development of Indo-Pacific biodiversity through time.
Proceedings of The Geologists Association, 2003
between the sexes in foraging Bar-tailed Godwits Limosa lapponica. Ardea 91(2): 268-272.
Living large benthic foraminifera (LBF) were analyzed from three transects of boxcores taken on a... more Living large benthic foraminifera (LBF) were analyzed from three transects of boxcores taken on a shelf off the coast of East Kalimantan, just north of the Mankalihat Peninsula. The transects were located at different distances to the mouth of the Berau river. In 45 boxcores, of which 28 contained living LBF, 20 species were recognised. They occurred in moderate to high density outside the pro-delta, i.e., outside the area with high clay and silt sedimentation. LBF characteristic of sandy substrates can be divided into two or possibly three assemblages, shallow (15-50 m), deep (50-85 m) and possibly very deep (N 85 m). The latter is poorly developed in the study area. Few LBF were recorded in one of the three transects, possibly because of either sediment instability or physical or chemical parameters of the sediment. Grain-size analysis of samples in the other transects indicates that LBF occurrence strongly modify the habitat. After colonisation, grain-size increases, creating more opportunities for other species and higher densities of LBF. D
Ecology, Jan 1, 2010
Reef ecosystems built during successive periods of Pleistocene sea level rise have shown remarkab... more Reef ecosystems built during successive periods of Pleistocene sea level rise have shown remarkable persistence in coral community structure, but little is known of the ecological characteristics of reef communities during periods of low sea stands or sea level falls. We sampled the relative species abundance of coral, benthic foraminifera, and calcareous red algae communities from eight submerged coral reefs in the Huon Gulf, Papua New Guinea, which formed during successive sea level fall and lowstand periods over the past ;416 kyr. We found that dissimilarity in coral species composition increased significantly with increasing time between reef-building events. However, neither coral diversity nor the taxonomic composition of benthic foraminifera and calcareous red algae assemblages varied significantly over time. The taxonomic composition of coral communities from lowstand reefs was significantly different from that of highstand reefs previously reported from the nearby Huon Peninsula. We interpret the community composition and temporal dynamics of lowstand reefs as a result of shifting energy regimes in the Huon Gulf, and differences between low and highstand reefs as a result of differences in the interaction between biotic and environmental factors between the Huon Gulf and Huon Peninsula. Regardless of the exact processes driving these trends, our study represents the first glimpse into the ecological dynamics of coral reefs during low sea level stands when climatic conditions for reef growth were much different and less optimal than during previously studied highstand periods.
This study is a preliminary assessment of an extremely diverse Tortonian (late Miocene) mollusk a... more This study is a preliminary assessment of an extremely diverse Tortonian (late Miocene) mollusk assemblage from a coral carpet environment preserved at Bontang (East Kalimantan, Indonesia). Even though coral-associated aragonitic faunas are rarely well preserved, the composition of the assemblage described here can be used to address the following questions: (1) How do the mollusk assemblages in coral habitats differ from other habitats, and What is the effect of sampling on estimates of taxon richness? The mollusk assemblage is dominated by predatory snails and includes typical modern coralassociated taxa such as the gastropod Coralliophila and the bivalve Tridacna. Our investigation implies that adequate documentation of Cenozoic mollusk diversity in the Indo-Pacific is even more challenging than previously expected as very large samples are required to capture species richness. Further assessments of fossil faunas from coral-dominated habitats will be required to provide insight to development of Indo-Pacific biodiversity through time.
Proceedings of The Geologists Association, 2003
between the sexes in foraging Bar-tailed Godwits Limosa lapponica. Ardea 91(2): 268-272.
Living large benthic foraminifera (LBF) were analyzed from three transects of boxcores taken on a... more Living large benthic foraminifera (LBF) were analyzed from three transects of boxcores taken on a shelf off the coast of East Kalimantan, just north of the Mankalihat Peninsula. The transects were located at different distances to the mouth of the Berau river. In 45 boxcores, of which 28 contained living LBF, 20 species were recognised. They occurred in moderate to high density outside the pro-delta, i.e., outside the area with high clay and silt sedimentation. LBF characteristic of sandy substrates can be divided into two or possibly three assemblages, shallow (15-50 m), deep (50-85 m) and possibly very deep (N 85 m). The latter is poorly developed in the study area. Few LBF were recorded in one of the three transects, possibly because of either sediment instability or physical or chemical parameters of the sediment. Grain-size analysis of samples in the other transects indicates that LBF occurrence strongly modify the habitat. After colonisation, grain-size increases, creating more opportunities for other species and higher densities of LBF. D