Modeling of the invasion and development of the pelagic communities of fouling organisms in the ocean

Abstract

The results of the modeling of the origin and development of the oceanic fouling biocenoses in the pelagic zone are presented. The models are relatively simple, but they are characterized by major peculiarities of the natural communities. The fouling communities are model objects to study the appearance and development of biological systems, invasions of hydrobionts, application of the bioindicator species, etc. The presented models take into account the most important interactions of the main fouling species (Lepadidae crustaceans are the dominating species) in typical regions and depths for such invasion and at the favorable abiotic environmental factors that are comparatively stable. The interaction between the meroplanktonic larvae of Lepas and Conchoderma (Lepadidae), represented by C. virgatum, L. anatifera, L. anserifera, and L. hillii, and the most widespread predators (crabs Planes minutus and the fish species) is modeled as the system of differential equations. In particular, the model covers the dynamics of colonies of fouling species, the “attractiveness” of these colonies to other fouling species, and the feeding rates of the predators consuming both the fouling species and associated fauna. The computing experiments showed that the population density changed markedly in the different age groups of Lepas and Conchoderma. The predator stress on Conchoderma was significantly higher than that on Lepas. The “attractiveness” of the biofouling organisms to cypris larvae and predators keeping near the substrate has a major impact on their density dynamics. The models showed that the crabs and especially fish had the strongest effect on the biocenoses of oceanic biofouling communities, limiting the population density of fouling species. When the presence of fish was excluded from the model, the abundance of Conchoderma increased rapidly and became similar to the abundance of Lepas. The model showed that the most important factors limiting the oceanic fouling are the settling rate of Lepadidae larvae to the substrate, “attractiveness” of the fouling organisms to predators, and the consumption of these animals by the predators. The models are in good correlation with experimental data of oceanographic buoy areas. Usage of the mathematical models for forecasting and assessing the invasion rates of biofouling organisms and the further development of their biocenoses is very promising and cannot be totally replaced by the other research methods. Analogous models can be developed for other communities and marine environments, for example, for the forecasting of hydrobiont invasions into the marine and freshwater bodies of Russia.