How Oceanic Microplastics Alter the Behavior of Marine Invertebrates

As microplastics are an incredibly and increasingly common pollutant in our oceans we must learn more about the the nature of the threats they pose to marine life and ecosystems. Research highlights a concerning connection between these tiny plastics and the cognitive abilities of marine invertebrates. In this post, we will explore how oceanic microplastics impact the development and cognitive functioning of these vital creatures. Understanding this relationship is crucial for appreciating the broader implications for marine biodiversity and health.

Understanding Microplastics

Microplastics are small plastic particles, measuring less than five millimeters and potentially as little as several nanometers. They come from the breakdown of larger plastic items or are manufactured as tiny beads found in cosmetics and industrial products. These particles enter the ocean through an almost unimaginably diverse set of pathways such as wastewater and runoff, littering on beaches, and even from the atmosphere. Once in the marine environment, microplastics can be ingested by a wide range of marine organisms. In this blog post, we'll be focusing on their effects on invertebrates like mollusks, crustaceans, and polychaete worms.

Cognitive Development in Marine Invertebrates

Marine invertebrates have complex nervous systems that allow for learning, memory, and decision-making. Octopuses are well-known for their intelligence, but even simpler much less intelligent creatures such as sea slugs exhibit signs of cognitive behavior.

When exposed to microplastics, these organisms end up dealing with a host of nasty physical and chemical effects that can play a role in hindering their cognitive abilities.

The Mechanisms at Play

The effects of microplastics on marine invertebrates tend to take three seperate forms:

1. Physical Blockages: Ingesting microplastics can cause blockages in the digestive system, or or simply make the organism feel less hungry which impacts nutrient gain and energy allocation. This lack of nutrients can stunt growth and cognitive development.

   
   

2. Chemical Contaminants: Microplastics often contain harmful contaminants, such as heavy metals and organic pollutants, which can seep into marine organisms. Additionally they can break down and degrade into toxic materials themselves. Studies show that exposure to these toxins results in neurological harm, negatively impacting brain function.

   
   

3. Altered Water Composition: Microplastics also change the chemical makeup of ocean water, creating a stressful environment for some types of marine life that are sensitive to chemical changes in the water. Research suggests that this stress can alter behavior in some marine invertebrates.

   
   

Behavioral Changes and Ecosystem Effects

There are many high quality studies in esteemed articles like Nature which highlight the negative effects of microplastics on the cognition of marine invertebrates. For example, some studies have found that shrimp exposed to heavily to microplastics through ingestion displayed a marked decrease in foraging efficiency and altered responses to predators. Other similar findings have been made across the range of marine invertebrates, from Crabs to Lobsters to Squid.

In several other studies, researchers have observed that bivalves (which are filter feeders) altered their feeding behavior after ingesting microplastics. This change resulted in in a marked decrease in both the organisms nutrient intake but on how much water they are actually filtering, affecting not only individual organisms but potentially disrupting entire ecosystems since bivalves play a crucial role in water filtration.

The cognitive decline from microplastic exposure has very serious implications beyond individual species. As invertebrates struggle with impaired foraging and predator avoidance behaviors, their survival rates plummet.

These population changes tend to have cascading effects throughout the food web. For example, if crab populations experience a decline in their ability to avoid predators due to cognitive impairments from the chemicals released by microplastics, this could lead to a downturn in fish populations that rely on crabs as a food source.