Advances in Oceanography and Limnology

Potentially toxic cyanobacteria in Trentino lakes: bloom episodes detected by monitoring data over the last ten years

Sabrina Pozzi, Silvia Costaraoss, Giovanna Pellegrini — Tue, 21 Jan 2025 00:00:00 +0000

This short note illustrates some algal blooms caused by potentially toxic cyanobacteria in water bodies in the NE Alps, focusing in particular on the last ten years. The data illustrated come from monitoring activities, bathing health assessments, and analyses carried out on citizen reports. The most important blooms were caused by Planktothrix rubescens, Dolichospermum spp., and Microcystis aeruginosa, and affected Lakes Ledro, Caldonazzo, and Serraia. Experience in the Trentino region has highlighted the importance of effective and timely communication between the monitoring institutions and the users of the lake, to minimize any negative health effects and to increase the knowledge of the population.

The complex relationship between cyanobacteria and antibiotics/antimicrobial resistance in the environment: an emerging factor in the One Health vision on antimicrobial resistance

Maura Manganelli, Emanuela Testai, Geoffrey A. Codd — Thu, 16 Jan 2025 00:00:00 +0000

In 2015, the World Health Organization (WHO) declared Antimicrobial Resistance (AMR) as one of the most critical health issues. It proposed, with the Food and Agriculture Organization (FAO) and OIE (World Organization for Animal Health), to address this by a One Health approach, recognizing the connection between humans, animals, and environmental health. Currently, a hypothesis is developing that cyanobacteria and cyanotoxins may contribute to AMR in water. Recent research appears to suggest: i) an impact of cyanotoxins on antibiotic-resistance gene transfer between bacteria; ii) a role of cyanobacteria as a reservoir of AMR. Finally, cyanotoxin production appears to be stimulated by cyanobacteria exposure to antibiotics.
These findings strengthen the importance of considering the environment in its complexity.

Implementation of surveillance plans for cyanobacteria in bathing waters: a case study from Lake Garda, Italy

Chiara Zampieri, Federica Giacomazzi, Giorgio Franzini — Thu, 16 Jan 2025 00:00:00 +0000

Since the beginning of the 1990s, Lake Garda has been affected by the development of surface blooms caused by the cyanobacterium Dolichospermum lemmermannii. Moreover, several other potentially toxigenic cyanobacteria were identified in the water samples collected during the monitoring activities, including the microcystins producer Planktothrix rubescens and a new species able to synthesize anatoxins (Tychonema bourrellyi). A plan has been activated by ARPAV (Regional Agency for Environmental Prevention of Veneto) to monitor algal communities and assess any risk of cyanobacterial proliferation that could affect the lake ecosystem and the bathing areas. In this work, we will briefly describe and critically comment on the main results obtained from the monitoring activities.

Anomalous colourations in surface water bodies: causes and examples reported by the Regional Agency for Environmental Protection and Energy of Emilia Romagna (ARPAE), Italy

Thu, 09 Jan 2025 00:00:00 +0000

Surface water can exhibit a range of colours beyond the expected blue or green. These anomalous colourations can be triggered by different factors, both natural and anthropogenic, and not always are signs of pollution. This note explores the phenomenon of water discolouration, focusing on natural causes and analysing how factors such as algal and bacterial blooms influence water colour. The study provides examples of specific events that occurred in the Emilia-Romagna region and documented by ARPAE and highlights the importance of monitoring these colouration events in order to provide valuable insights into the health of water bodies and the surrounding environment.

Understanding cyanobacteria and cyanotoxins: implications for human exposure, toxicological risk assessment and management

Emanuela Testai — Mon, 16 Dec 2024 00:00:00 +0000

Cyanobacteria, often referred to as blue-green algae, are a diverse group of photosynthetic bacteria that play a crucial role in various ecosystems. However, their proliferation and toxin production pose significant challenges to environmental, animal, and human health. In recent years, the interplay between cyanobacteria, climate change, and the production of cyanotoxins has garnered increased attention. This short note aims to delve into the intricate relationship between cyanobacteria and the production of cyanotoxins, the toxicological risks associated with exposure, and strategies for risk assessment and management.

Rossby waves impact on persistent oxic and suboxic chlorophyll maxima in the Eastern Tropical North Pacific

Thu, 19 Sep 2024 00:00:00 +0000

This study aims to describe the response of two persistent chlorophyll-a maxima to physical processes that affect the po- sition of the thermocline/nitracline in the Eastern Tropical North Pacific (ETNP). We focused on Long Rossby Waves (LRWs) due to their relevance to the ETNP circulation and their potential role in introducing nutrients into the euphotic zone. We found that the shallower chlorophyll-a maximum in oxygenated waters became more intense when denser waters (containing more nu- trients) moved toward the surface. This suggests that changes in isopycnals and nitracline displacements modify nutrient supply in the euphotic zone, leading to changes in phytoplankton growth. The suboxic and deeper chlorophyll-a maximum showed a strong association with the 26 kg m-3 isopycnal, which was only mechanically displaced, and its chlorophyll-a content did not seem to covary with irradiance or nutrients. The decor- related responses of the chlorophyll-a maxima could be ex- plained if different phytoplankton groups are associated with them. LRWs can affect the position of the thermocline/nitracline and isopycnals in an annual cycle, but it seems to be a “back- ground” signal modulated by higher frequency processes such as mesoscale eddies and other Rossby waves. The co-occurrence of processes can control the nitracline depth, and thus the input of nutrients into the euphotic zone, leading to sporadic enhance- ments in chlorophyll-a concentration in one maximum.

Analysis of main components of Lake Toba’s water quality in different seasons

Tue, 19 Mar 2024 00:00:00 +0000

Lake Toba is one of the largest lakes in North Sumatra Province, Indonesia. Its waters are used for multiple purposes, constituting an important natural and economic resource. Most of the waters of Lake Toba come from the overflow of disposal of agriculture, livestock, fisheries, tourism, households, and other activities. The present study identified water quality based on total nitrogen, total phosphorus, chlorophyll-a and other water quality parameters carried out at 60 sampling sites grouped into 6 observation stations, i.e., control areas (located in the middle and far from direct activities), community floating net cages, company floating net cages, settlement, hospitality, and river mouths. The main water quality components were very dynamic at the monitoring stations in three seasons (rainy, transition, and dry). Total nitrogen concentration tended to be higher in the rainy season than in the transition and dry seasons. However, all stations tended to be classified as mesotrophic or higher in all seasons, with total nitrogen concentrations greater than 12.5 mg L–1. Total phosphorus at the six stations was highly dynamic in all seasons and tended to decrease in the dry season. The concentration of total phosphorus was higher at the settlement and hospitality stations than at the other stations. The total phosphorus of the settlement and hospitality stations reached 0.18 mg L–1 and 0.17 mg L–1, respectively, in the rainy season. In general, total phosphorus concentrations in the waters of Lake Toba were above 0.1 mg L–1, which allowed the lake to be classified as above mesotrophic status.