Gary Braasch is an environmental photographer and writer. He covers natural history and conservation issues for magazines worldwide. In recent years photographs and articles of...
Aquatic Invasive SpeciesLast Updated on 2008-09-17 00:00:00
Thousands of freshwater, estuarine, and marine species have been dispersed or transplanted across the globe by humans. These aquatic invasive species arrive in the ballast or on the hulls of ships, through the movement of shellfish and bait, by the opening of new channels or canals, through intentional release, and other vectors. Once established, they can change ecosystems, reduce native biodiversity. and impact local economies. Aquatic communities are becoming increasingly homogenized as a result.
Figure 1. The waterflea Daphnia pulex, common to eutrophic, or nutrient-rich, freshwater systems. (Image courtesy of Paul Hebert)
In recent years, the introduction rate of plants, animals, and protists and other microorganisms has been accelerating. The invasion rate of freshwater cladocera, small crustaceans such as the water flea Daphnia, is now 50,000 times higher than the... More »
PlanktonLast Updated on 2008-09-17 00:00:00
Diatom, Thalassiosira pseudonana. (Source: U.S. Department of Energy Joint Genome Institute)
Plankton are drifting organisms in aquatic environments, including marine and fresh water. They are the base of the food web in these environments.
Plankton can be divided into broad functional (or trophic level) groups:
Phytoplankton are tiny (usually unicellular) algae that live near the water surface where there is sufficient light to support photosynthesis. Among the more important groups are the diatoms, coccolithophores, cyanobacteria and dinoflagellates.
Zooplankton are small protists or metazoans (e.g. crustaceans and other animals) that feed on the phytoplankton. Larval stages of larger animals, such as fish, crustaceans, and annelids are included here. Zooplankton are in turn consumed by small fishes.
Bacterioplankton are bacteria and archaea which play an important role in... More »
Threats to Coral ReefsLast Updated on 2008-09-17 00:00:00
Coral reefs have been experiencing damage from a number of sources. It is estimated that 10% of all coral reefs are already degraded beyond repair, with 30% estimated to be in critical condition and at risk of death within 10 – 20 years. If current pressures continue then 60% of the world’s coral reefs may be severely damaged by 2050. The damage/degradation can be due to natural events and or anthropogenic effects.
Sri Lankan reefs damaged by a tsunami. (Source: National Aquatic Resources Research and Development Agency)
Coral reefs can be damaged by natural events such as hurricanes, cyclones, and tsunamis. Wave activity can break apart corals; branching corals are more susceptible to storm damage than mound-building corals. Storms rarely kill all corals, and because storms are a natural part of coral reef ecosystems, coral species should be adapted to this... More »
Rising TidesLast Updated on 2008-09-16 15:12:07About The Cover Shot: Erosion along Cape Hatteras North Carolina has been about 12 feet per year in recent years, leaving house after house stranded in the surf, awaiting its destruction. This is due to a combination of rising sea level and stronger storms and hurricanes, effects of increasing warmth in the atmosphere and ocean. Federal insurance guarantees money for rebuilding, and local officials continue to bulldoze sand back onto beaches -- both of which actions actually increase erosion damage, according to scientists.
The world is catching up to Gary Braasch. "This was not a very well covered issue when I started six years ago," he says. The issue is global warming, and what Gary started was an ongoing project to document the results of climate change.
Gary Braasch is an environmental photographer and writer. He covers natural history and conservation issues for... More »
Coral reefs and climate changeLast Updated on 2008-09-16 10:33:19
A reefscape from the Great Barrier Reef. (Photo credit: AIMS LTMP)
Research on the current and future impacts of human-induced climate change on reef-building corals is causing scientists and managers to become increasingly concerned about the future of coral reefs. A healthy reef ecosystem literally buzzes with sounds, activity and colors and is populated by incredibly dense aggregations of fish and invertebrates. In this respect, tropical reefs are more reminiscent of the African Serengeti than of the tropical rainforest they are often compared to, where the resident birds and mammals can be secretive and difficult to see. A coral reef can contain tens of thousands of species and some of the world’s most dense and diverse communities of vertebrate animals. Unfortunately, very few remaining coral reefs resemble this pristine condition; on most, corals and fishes are much... More »
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