Seasonal and Interannual Variability of Satellite-Derived Chlorophyll-a (2003-2019) in Lampung waters and surrounding area

In recent years, the phytoplankton blooming phenomenon occurred at Lampung Waters. This event harms living organisms due to its toxicity or caused oxygen depletion. Chlorophyll-a concentration (Chl-a) is the crucial biological parameter for simulating marine phytoplankton biomass. In this study, the monthly average of Chl-a ocean-color remote sensing data from 2003 to 2019 is investigated. The seasonal and interannual variability of Chl-a was analyzed in Lampung waters and its surrounding area. The study area was separated into three regions, namely the East Coast of Lampung waters, Lampung Bay and Sunda Strait area. The spatial pattern showed that the value of Chl-a on the east coast was higher than Lampung Bay and Sunda Strait, with a deal up to 7 mg/mg/m 3. The time series of spatial averages in three areas showed the seasonal and inter-annual variation. The monthly climatology of Chl-a in Lampung Bay more influenced by sea surface temperature. The maximum value occurs in October with Chl-a concentration was 0,87 mg/m 3. Meanwhile, the east coast area and Sunda Strait fit with the monthly rainfall pattern in the Lampung mainland. The maximum value occurs in February with Chl-a abundance were 2,49 mg/m 3 and 0,96 mg/m 3, respectively. The value indicated that the river runoff would be a significant impact on phytoplankton blooming. Otherwise, the interannual variability in three areas showed that the Lampung Bay was more influenced by Indian Ocean Dipole than the East Coast and Sunda Strait. The cross-correlation between Chl-a concentration and Dipole Mode Index in East Coast area, Lampung Bay, and Sunda Straits are -0.2, 0.5, and 0,1, with a significant level of 95%.

Automatic Pipeline for Detection and Classification of Phytoplankton Specimens in Digital Microscopy Images of Freshwater Samples

Phytoplankton blooming can compromise the quality of the water and its safety due to the negative effects of the toxins that some species produce. Therefore, the continuous monitoring of water sources is typically required. This task is commonly and routinely performed by specialists manually, which represents a major limitation in the quality and quantity of these studies. We present an accurate methodology to automate this task using multi-specimen images of phytoplankton which are acquired by regular microscopes. The presented fully automatic pipeline is capable of detecting and segmenting individual specimens using classic computer vision algorithms. Furthermore, the method can fuse sparse specimens and colonies when needed. Moreover, the system can differentiate genuine phytoplankton from other similar non-phytoplanktonic objects like zooplankton and detritus. These genuine phytoplankton specimens can also be classified in a target set of species, with special focus on the toxin-producing ones. The experiments demonstrate satisfactory and accurate results in each one of the different steps that compose this pipeline. Thus, this fully automatic system can aid the specialists in the routine analysis of water sources.

The Reproductive Cycle of Holothuria Cucumaria frondosa of the Barents Sea

The study considers the morphological features of the gonad structure and the seasonal changes in the reproductive activity of the gonads of holothuria Cucumaria frondosa of the Barents Sea. The sex of individuals can be identified using morphometric analysis with the average mass of gonads of 1.63 g, with the average mass of the skin-muscle sac of 53.00 g and the length of 80.00-83.00 mm whereas the diameter of the genital tubes is not less than 0.50 mm. The spawning of cucumaria, producing plankton progeny, occurs from March to May, but the spawning period can be shifted, since the beginning of the spawning period is associated with the seasonal increase of the surface water temperature and the intensive phytoplankton blooming. The character of spawning is intermittent. Individual fertility is low, in individuals with the average mass of SMS 150.00-200.00 g ranged from 9 to 32 thousand cells.

Impact of Lake Morphology and Shallowing on the Rate of Overgrowth in Hard-Water Eutrophic Lakes

Lake disappearance is one of the results of water eutrophication which leads to lake shallowing and overgrowth, and small and shallow lakes are the most threatened with degradation. We studied the effect of lake shallowing on its overgrowth, taking into account the morphometric parameters of water bodies. The study was performed in 20 lakes located in the central west part of Poland. The degree of lake shallowing was evaluated on the basis of bathymetric maps made in the 1960s and studies carried out presently. Additionally, an analysis of littoral coverage and macrophyte growth forms was investigated. Moreover, the composition, intensity of phytoplankton blooming, and physico-chemical parameters of the lake water were analyzed. Redundancy analysis shows that the lake volume, average depth, shallowing rate, and change in volume were the parameters that most strongly correlated with the share of macrophytes in the lakes. According to the regression analysis, the share of emergent macrophytes was significantly correlated with lake shallowing. No relation was found between phytoplankton blooming and lake shallowing. Conversely, the lakes with the highest rate of shallowing were characterized by the greatest share of vegetation, which suggested that vegetation growth had a significant impact on lake shallowing.