Ocean VL 7 Flashcards
How did plastic become an environmental problem in marine ecosystems?
Plastic pollution has been recognized since the 1970s, with 80% of marine plastic debris originating from terrestrial sources. It is primarily composed of packaging materials, fishing equipment, and losses during production and transport.
What is the Great Pacific Garbage Patch, and how are plastics distributed in marine systems?
The Great Pacific Garbage Patch is a high-concentration area of plastic debris within oceanic gyres.
Plastics accumulate due to ocean currents, with millions of particles per square kilometer in areas like the North Pacific and North Atlantic gyres.
How does plastic fragmentation occur in aquatic environments?
Plastics break down from macroplastics (large pieces) into mesoplastics and microplastics due to physical, chemical, and biological processes. A single macroplastic item can fragment into thousands of microplastic particles, contributing to widespread pollution.
What are the key processes that lead to the loss of plastic fragments from surface waters?
Plastic fragments can degrade via:
* UV light,
* biodegradation,
* or ingestion by organisms.
They can also lose buoyancy due
* to fouling organisms or
* become buried in sediments through beaching or entrainment in settling detritus.
What are microplastics, and how are they classified?
- Microplastics are plastic particles smaller than 5 mm.
- They can be primary (produced intentionally, like plastic pellets) or secondary (formed through the breakdown of larger plastic debris).
- Their distribution in water is influenced by polymer density and environmental factors.
What methods are used to sample microplastics in aquatic environments?
Sampling methods include
* Manta Trawls for surface water,
* Continuous Plankton Recorders for suspended particles, and
* density-based separation techniques like froth flotation for sediments.
These methods help capture plastic particles from different water layers and habitats.
Which marine organisms ingest microplastics, and what are the potential effects?
Marine organisms like invertebrates (e.g., barnacles, mussels, zooplankton) and vertebrates (e.g., fish, turtles, birds) ingest microplastics.
Ingestion can lead to reduced feeding efficiency, reproductive impairment, and possible trophic transfer, although biomagnification is not well documented.
What does affect microplastic ingestion by fish species?
Microplastics are ingested by fish based on their feeding behavior, size, and prey selection capability.
Factors like the color of plastics (e.g., preference for black) and developmental condition can influence ingestion, although there is no clear pattern across species.
Why are microplastics in freshwater systems significant, and how do they differ from marine microplastics?
Freshwater systems are a major source of marine plastics, with rivers transporting large quantities to the oceans. Microplastics in freshwater are easier to control than in marine environments but are influenced by specific hydrology, biogeochemistry, and local land use.
How do microplastic concentrations in rivers compare to oceans?
Concentrations of microplastics in rivers are 40-50 times higher than in the open ocean.
Rivers like the Yangtze and Danube transport significant amounts of microplastics, and their inputs are correlated with mismanaged plastic waste from surrounding areas.
What is the potential for trophic transfer of microplastics in aquatic food webs?
Microplastics can be transferred through the food web as smaller organisms ingest them and are then eaten by predators.
While trophic transfer occurs, there is no clear evidence of biomagnification, where the concentration of microplastics increases at higher trophic levels.
What are some harmful effects of plastic debris on marine organisms?
Plastics can entangle and strangle marine animals, be mistaken for food leading to ingestion, act as vectors for pathogens, and adsorb harmful substances that are then released into organisms upon ingestion, affecting their health and survival.
How does microplastic contamination affect bivalves like mussels and oysters?
Bivalves can accumulate microplastics in their tissues, with cultured mussels and oysters showing high contamination levels.
European consumers ingest up to 11,000 microplastic particles per year through shellfish consumption, raising concerns about food safety and human health.
How do dams influence microplastic distribution in freshwater systems?
Dams can act as sinks for microplastics, with differences observed in concentrations upstream and downstream of dams. Microplastics tend to accumulate in reservoirs, impacting local aquatic life and contributing to pollution downstream.
How are plastic materials identified in environmental samples?
Plastics can be identified through optical methods,
* Raman microspectroscopy, and
* FTIR spectroscopy.
These techniques allow for the precise identification of polymers, though small particles may be overlooked or require complex sample preparation and analysis.
