Wayne Sousa
Encyclopedia
Wayne Sousa is a well-known biologist
and ecologist. He works at the University of California, Berkeley
as a professor and chair of the Department of Integrative Biology. His research in community ecology has been in two broad areas: the role of disturbance in structuring natural communities and the ecology of host-parasite interactions. There is a lab on the UC Berkeley campus named after him. In his lab students work alongside Sousa on research topics such as mangrove forest gap regeneration, the demographics of intertidal algae in California, plant invasions in coastal California grasslands, and rainforest seedlings in Ecuador.
The surf overturns boulders of all shapes and sizes, but smaller boulders are overturned at a more frequent rate, allowing less time for plants and animals to use them as a resource. From this information it appears that the larger boulder would have the greatest diversity, however Sousa found that this hypothesis was incorrect. Large boulders usually have less biota than intermediate sized boulders, because they are inundated with one species of red algae
, it is only after winter that the algae defoliates when other organisms can inhabit the boulder.
Sousa discovered barnacles and Ulva, a fast succession species of green alga, inhabit the small boulders; these species essentially “took over” the resources of the boulder before any other organism had an opportunity. Intermediate boulders have the most varied communities, consisting numerous types of organisms; this study found barnacles, Ulva, quick succeeding red alga, and sometimes the late accumulating red alga, Gigartina canaliculata was also present. These areas are the best in terms of species survival. The large, infrequently moving boulders are covered with the Gigartina canaliculata; once this alga dominates the boulder other species get “kicked out” or cannot find space to live there.
organisms.”
forest dynamics. Because of coastal development, resource exploitation, pollution and other environmental hazards, mangrove forests are in danger of extinction worldwide. “In the Caribbean, the rate of mainland mangrove deforestation is 1.4-1.7% annually, comparable to rates for threatened tropical rainforests. The information Sousa and colleagues collect on natural patterns of mangrove regeneration is critical to management and conservation of these unique habitats.” He uses techniques of sampling and other various experiments to discover the reason for spatial and temporal pattern differences seen in gaps in the arbor canopy. The process to potentially fill those gaps with vegetation is called regeneration.
One experiment, to find why sapling mangroves were not succeeding, found that damage by insects at critical stages in development were the problem. He measured three common species of mangroves in Panama, these species showed an intraspecific variation of propagule
size, and were disposed to attacks from larval insects. The insect predation did not focus on a single mangrove or propagule size; but the study found that larger propagules developed more rapidly, thus having a better chance at survival.
Biologist
A biologist is a scientist devoted to and producing results in biology through the study of life. Typically biologists study organisms and their relationship to their environment. Biologists involved in basic research attempt to discover underlying mechanisms that govern how organisms work...
and ecologist. He works at the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
as a professor and chair of the Department of Integrative Biology. His research in community ecology has been in two broad areas: the role of disturbance in structuring natural communities and the ecology of host-parasite interactions. There is a lab on the UC Berkeley campus named after him. In his lab students work alongside Sousa on research topics such as mangrove forest gap regeneration, the demographics of intertidal algae in California, plant invasions in coastal California grasslands, and rainforest seedlings in Ecuador.
Methods
For his dissertation he studied species diversity on intertidal boulders in Ellwood Beach, California. He organized his study by boulder size as well as frequency of being tumbled by the waves; boulders were put into groups of small, intermediate, and large depending on the force it would take a wave to move it. The study began in April 1975, and species richness was measured monthly on all three sizes of boulders, until May 1977.The surf overturns boulders of all shapes and sizes, but smaller boulders are overturned at a more frequent rate, allowing less time for plants and animals to use them as a resource. From this information it appears that the larger boulder would have the greatest diversity, however Sousa found that this hypothesis was incorrect. Large boulders usually have less biota than intermediate sized boulders, because they are inundated with one species of red algae
Red algae
The red algae are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species of mostly multicellular, marine algae, including many notable seaweeds...
, it is only after winter that the algae defoliates when other organisms can inhabit the boulder.
Sousa discovered barnacles and Ulva, a fast succession species of green alga, inhabit the small boulders; these species essentially “took over” the resources of the boulder before any other organism had an opportunity. Intermediate boulders have the most varied communities, consisting numerous types of organisms; this study found barnacles, Ulva, quick succeeding red alga, and sometimes the late accumulating red alga, Gigartina canaliculata was also present. These areas are the best in terms of species survival. The large, infrequently moving boulders are covered with the Gigartina canaliculata; once this alga dominates the boulder other species get “kicked out” or cannot find space to live there.
Findings
The seasons did affect the Variation of species type and dominance on the boulders. However, while time was an important factor it did not make the experiment’s findings inconclusive. It is common for populations to go extinct than to remain stable in such a harsh environment, as an intertidal zone. But the study was conclusive and added support for the theory of nonequilibrium community structure, “suggesting that open space is necessary for the maintenance of diversity in most communities of sessileSessility (limnology)
In limnology, sessility is that quality of an organism which rests unsupported directly on a base, either attached or unattached to a substrate. It is a characteristic of vegetation which is anchored to the benthic environment. There are two families of sessile rotifers: Flosculariidae and...
organisms.”
Methods
His current research is on Caribbean MangroveMangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
forest dynamics. Because of coastal development, resource exploitation, pollution and other environmental hazards, mangrove forests are in danger of extinction worldwide. “In the Caribbean, the rate of mainland mangrove deforestation is 1.4-1.7% annually, comparable to rates for threatened tropical rainforests. The information Sousa and colleagues collect on natural patterns of mangrove regeneration is critical to management and conservation of these unique habitats.” He uses techniques of sampling and other various experiments to discover the reason for spatial and temporal pattern differences seen in gaps in the arbor canopy. The process to potentially fill those gaps with vegetation is called regeneration.
One experiment, to find why sapling mangroves were not succeeding, found that damage by insects at critical stages in development were the problem. He measured three common species of mangroves in Panama, these species showed an intraspecific variation of propagule
Propagule
In horticulture, a propagule is any plant material used for the purpose of plant propagation. In asexual reproduction, a propagule may be a woody, semi-hardwood, or softwood cutting, leaf section, or any number of other plant parts. In sexual reproduction, a propagule is a seed or spore...
size, and were disposed to attacks from larval insects. The insect predation did not focus on a single mangrove or propagule size; but the study found that larger propagules developed more rapidly, thus having a better chance at survival.