01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-05-0012 |
| Title of Abstract | IMPACT OF NOCTILUCA BLOOM ON MICROZOOPLANKTON COMMUNITY STRUCTURE IN A TROPICAL ESTUARY (UDYAVARA, KARNATAKA) |
| Authors | Smruthu Mohan*, Geetha Sasikumar |
| Organisation | Indian national Centre for Ocean Information Services |
| Address | 402, Manya Pride, Incois Road Hyderabad, Telangana, India Pincode: 500090 E-mail: m.smruthu-p@incois.gov.in |
| Country | India |
| Presentation | Oral |
| Abstract | This study investigates the impact of a Noctiluca bloom on the community structure of microzooplankton in the Udyavara estuary, Karnataka, India, in November 2020. The Udyavara estuary, a dynamic coastal ecosystem, is periodically affected by harmful algal blooms, including those of Noctiluca. In this study, we measured parameters such as pH, salinity, dissolved oxygen (DO), biological oxygen demand (BOD), chlorophyll pigments (Chl a, b, c), total suspended solids (TSS), particulate inorganic matter (PIM), particulate organic matter (POM), and nutrient levels (nitrite, nitrate, phosphate, silicate, ammonia) across three stations: one experiencing a bloom and two without. Results from the bloom-affected station revealed elevated pH (7.350⿿7.410) and salinity (30.8 ppt) levels, with notably lower silicate concentrations (0.55⿿1.91 µgL-1) and reduced chlorophyll a (0.109⿿0.110 mg m-³), reflecting disrupted nutrient dynamics and a decline in phytoplankton diversity. The microzooplankton community at the bloom site was dominated by Noctiluca (0.9 ÿ 105 - 4.6 ÿ 105 No L-1), leading to a significant reduction in other taxa such as tintinnids and dinoflagellates, which were nearly absent or present in very low densities (0⿿4 ÿ 103 No L-1). Other dinoflagellates showed a similar pattern, with higher numbers in stations unaffected by the bloom. In contrast, non-bloom stations exhibited more balanced ecological conditions, with higher chlorophyll-a levels (0.252⿿0.445 mg m-³) and a more diverse microzooplankton community, including various species of rotifers, nauplii, tintinnids, and other dinoflagellates. These findings indicate that Noctiluca blooms significantly alter the microzooplankton community structure affecting the estuarine ecosystem's overall trophic dynamics and nutrient cycling. This study underscores the need for continuous monitoring and management strategies to mitigate the impacts of such blooms on coastal marine ecosystems. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Noctiluca bloom, Community structure, Microzooplankton |
| For Awards | yes |
| Date Of Birth | 11-11-1989 |
| ECSN Registration Number | IIOE2-ECSN-0108 |