10 research outputs found
Recovery dynamics of mechanically damaged scleractinian corals of the genus Porites under different light intensities
Identifying nitrogen sources for macroalgal growth in variously polluted coastal areas of southern Vietnam
Finding the winners in competition for substratum between coral polyps and epilithic algae on damaged colonies of the coral Porites lutea
Community Structure of Free-living Marine Nematodes in the Area of Agar-Producing Alga Ahnfeltia To b u c h i e n s i s Field (Starka Strait, Peter the Great Bay, East Sea)
Adaptive variation in coral geometry and the optimization of internal colony light climates
1. The ability of photosynthetic organisms to adjust their light climate has high adaptive significance because irradiance can vary spatially by orders of magnitude. Using a plating (foliaceous) coral species (Turbinaria mesenterina), we tested the hypothesis that plasticity of colony geometry optimizes internal irradiance distributions. 2. We developed a two-dimensional model to predict the internal irradiance distribution of a foliaceous colony as a function of its geometry. Field tests showed that the model explained 85% of the variation in irradiance within colonies of T. mesenterina with minimal bias. 3. Colony plate angle, plate spacing and range of tissue distributions into the colony were exponential functions of water depth. In shallow water plates tended to be nearly vertical, narrowly spaced, and had living tissue only near the growing edge of the plate. In deep water plates grew more horizontally, were more widely spaced, and had living tissue extending well into the colony interior. This pattern of phenotypic plasticity effectively evens out differences in within-colony irradiances. 4. We compared within-colony irradiance distributions across light habitats (depth), based on the observed variation in colony geometry with water depth. Despite fourfold differences in environmental irradiance, within-colony irradiances had a common mode of 100-200 mu mol m(-2) s(-1). This is near the hypothesized photosynthetic optimum defined by the upper limit of the subsaturation parameter (E-k) of the photosynthesis-irradiance curve. 5. Our study demonstrates that phenotypic plasticity of colony geometry is an important mechanism for regulating light capture during growth in T. mesenterina, and facilitates near-optimal internal irradiances across a wide range of environmental light regimes
Checklist of marine benthic green algae (Chlorophyta) at the subtropical island of Hainan (China): A comparison between the 1930s and 1990-2009 reveals environmental changes
A complete checklist of intertidal to shallow subtidal marine
green seaweeds (Chlorophyta) growing on the subtropical
island of Hainan (China) is presented here for the fi rst time.
It covers data from extensive recent (1990 – 2009) and historical
(1933 – 1935) collections, and additional published records
from various time periods. Data were analyzed by time period.
We postulate that environmental changes on Hainan Island
documented since the 1980s (e.g., degradation of coral reefs,
development of tourism and mariculture farms) are refl ected in
the green algal species complement and in the dominance or
absence of specifi c algal groups during different time periods.
In total, 105 green algal taxa were recorded, including 37 new
to Hainan Island, and 18 new records for China. There was a
clearly evident change in fl oristic composition between early
and recent collections. In the 1930s, there was a dominance of
Caulerpaceae, Codiaceae and Cladophoraceae. By 1990/1992,
the numbers of Ulvaceae had increased 1.6-fold and numbers
of Cladophoraceae 1.7-fold. Both families contain many
opportunistic species that prefer nutrient-enriched or degraded
environments. At the same time, species richness of Codiaceae,
Caulerpaceae and Udotaceae, families with complex thallus
structures, decreased considerably. The fl oristic differences
between the 1990/1992 and 2008/2009 collections were minor