Stationary distribution of a stochastic hybrid phytoplankton model with allelopathy

This research proposes and delves into a stochastic competitive phytoplankton model with allelopathy and regime-switching. Sufficient criteria are proffered to ensure that the model possesses a unique ergodic stationary distribution (UESD). Furthermore, it is testified that these criteria are sharp on certain conditions. Some critical functions of regime-switching on the existence of a UESD of the model are disclosed: regime-switching could lead to the appearance of the UESD. The theoretical findings are also applied to research the evolution of Heterocapsa triquetra and Chrysocromulina polylepis.

A prolonged red tide of Heterocapsa triquetra (Ehrenberg) F. Stein (Dinophyceae) and phytoplankton succession in a eutrophic estuary in Turkey

A prolonged red tide of Heterocapsa triquetra and phytoplankton succession were investigated in a eutrophic estuary (Golden Horn) for a year. Runoff following the rainfall in winter supplied high amounts of nutrients and also created a mesohaline frontal zone in the middle and upper estuary. Red tide of H. triquetra was first observed with an orange-brownish water discoloration at the upper estuary in January. Highest cell density of H. triquetra was 2.7×106 cells l-1 in January and reached to 19.2×106 cells l-1 in April. Successive blooms continued with dinoflagellate Prorocentrum minimum in May and phytoflagellates Eutreptiella marina and Fibrocapsa sp. in summer. High chl-a and dissolved oxygen were measured in the spring depending on algal biomass. Findings indicate that H. triquetra might be adapted to moderate salinity and low temperatures and red tide events should be considered as a response to increasing eutrophication due to high amounts of nutrients. Eutrophication can lead to harmful algal blooms for this area in the near future.

The effect of irradiance on the xanthophyll composition of Skeletonema marinoi (Bacillariophycae), Teleaulax sp., Rhodomonas sp. (Cryptophyceae), and Heterocapsa triquetra (Dinophyceae)

The aim of the research was to determine the effect of irradiance on the content of carotenoids in the natural algae community occurring in the Baltic Sea: diatom Skeletonema marinoi, cryptophytes Teleaulax sp., Rhodomonas sp., and dinoflagellate Heterocapsa triquetra.In the natural population of Skeletonema marinoi, the highest fucoxanthin content was observed in the morning and afternoon, unlike with diatoxanthin+diadinoxanthin, where a mean of 0.008 pg cellIn cryptophytes Teleaulax sp. and Rhodomonas sp., no carotenoids of the xanthophyll cycle were detected. The content of alloxanthin showed diurnal variation from 0.048 pg cell