Key prey indicates high resilience on marine soft bottom habitats

Area of Science:

• Marine Ecology
• Fisheries Science
• Quantitative Ecology

Background:

• Understanding predator-prey dynamics is essential for marine ecosystem management.
• Nektonic communities play a vital role in marine food webs.
• Identifying key prey aids in assessing ecosystem stability and resilience.

Purpose of the Study:

• To develop and apply a novel, accessible tool for identifying key prey within nektonic communities.
• To analyze the dietary sources and habitat-specific prey preferences of nektonic assemblages in southern Brazil.
• To evaluate the implications of key prey identification for predator population stability and ecosystem health.

Main Methods:

• Utilized simple probabilistic methods and web-based analytical procedures for key prey discrimination.
• Employed an adapted outlier analysis, including principal component analysis (PCA), to objectively select key prey.
• Analyzed the diets of indicator species across coastal and continental shelf habitats.

Main Results:

• Identified three key prey species: Artemesia longinaris (coastal), Euphausia similis, and Engraulis anchoita (continental shelf).
• Found that pelagic and detritus were primary energy sources for all analyzed nektonic assemblages.
• Observed distinct feeding strategies: coastal nekton accessed benthic food webs, while shelf assemblages utilized pelagic and benthic resources differently based on temperature.

Conclusions:

• Key prey identification is critical for predicting predator population stability in response to environmental changes.
• Nektonic community structure and prey availability are influenced by habitat and oceanographic conditions.
• Demersal nekton's resilience may obscure the long-term impacts of fishing, highlighting the importance of accurate prey assessment.