effect of short-term meteorological disturbances on the submerged aquatic vegetation and associated fauna in the Patos Lagoon estuary, southern Brazil

Occluded fronts are naturally cyclogenic areas that have been intensified by global warming. Studies evaluating the effects of occluded fronts in the submerged aquatic vegetation (SAV) and its associated fauna in shallow estuarine areas may provide insights on the impacts of climate change-induced extreme weather events on coastal ecosystems functioning. The present dataset describes data on benthic fauna and flora in the Patos Lagoon Estuary (PLE), in southern Brazil, seasonally obtained during intense occluded fronts. Using a hierarchical sample design, based on Beyond BACI protocols (Before/After and Control/Impact), fauna and flora were sampled before and after four occluded fronts passage throughout 2019.Three habitats were sampled: SAV Meadow, SAV Edge and adjacent Sandflat. A total of 432 macrozoobenthic samples (216 samples for stratum); 216 samples for bellow and aboveground biomass, vegetation coverage, canopy height and marine macrophytes morphology; 144 samples by sedimentology and organic matter; 72 water column depth measurements; and 8 temperature and salinity measurements were collected during the study period. The data is available at the Global Biodiversity Information Facility (GBIF), in Darwin Core standard format (DwC), organized according to the OBIS-ENV-DATA model, with CC-BY-NC-4-0 license for use. The present dataset adds to the comprehension of the temporal variability of estuarine benthic communities in subtropical systems, and how short-term meteorological process can affect zoo and fitobenthic communities in the context of climate changes.

Human-induced influence on eggs and larval fish transport in a subtropical estuary

The transport during the early stages of life to the nursery areas is one of the main processes in the maintenance of the marine fish population, and human interventions can interfere with this process. In this work, the TELEMAC-3D model coupled to passive particles was used to understand the effect of the change in the configuration of the Barra Jetties of the Rio Grande regarding the transport of eggs and larvae of the croaker Micropogonias furnieri in the Patos Lagoon estuary (PLE). Twelve experiments of 5 days that consisted of periods of high and low discharge combined with winds from the south quadrant (SW, S, and SE) were carried out to test the hypothesis that human interventions in the coastal region alter the transport patterns of fish eggs and larvae. The low flow guaranteed a greater extent of saline intrusion and larvae incursion in the estuary, with the opposite occurring in the scenario of high flow. The SW wind ensured the most efficient recruitment into the estuary, in terms of both entry time and maximum reach in both configurations. However, the recent modernization works of the Barra Jetties have changed the pattern of transport and dispersal of larvae and have reduced the amount and reach of the incursion of croaker eggs and larvae into the estuary compared to their old configuration. With the new configuration of jetties, reductions in the larvae concentration and abundance in the estuary were registered at approximately 25 % for SW and S winds, 68.6 % for SE wind at high discharge, and 0.5 % to 1 % for winds at low discharge. The lateral stratification in the access channel to the estuary, an important parameter in the larvae transport and distribution between the jetties and the predominant wind direction, was decisive in defining the initiation time of the stratification. With the old configuration, the lateral stratification was established 1 h, 7 h, and 10 h after starting the simulation with the incidence of SW, S and SE winds, respectively. In the new configuration, the lateral stratification was established at the same time only with the SW wind, but with a reduced salinity gradient. In this configuration, only the beginning of stratification was observed at the estuary mouth with S winds, while the stratification was not established with SE winds. This fact influenced the intrusion of saline water and resulted in a smaller number of larvae between the jetties and consequently their transport into the estuary. With the new configuration, a reduction in the maximum penetration of the larvae within the estuary was observed at 1.6 km for high discharge and 2.3 km for low discharge. Despite limitations inherent to the numerical modeling technique, the results obtained corroborate the hypothesis that human interventions in the coastal region change the patterns of transport of fish eggs and larvae. Furthermore, the findings suggest that modernization works of the jetties have contributed to reducing the transport of dependent estuarine species to the Patos Lagoon estuary. Coupled with the knowledge obtained by other research about this species, this knowledge can support provisioning measures for better management of fishery resources in the region.

NUMERICAL STUDY OF OIL SPILL IN THE PATOS LAGOON ESTUARY REGION

The consumption pattern of the world population is based on petroleum derivatives, which despite contributing to the improvement of the quality of life, has negative aspects, mainly in the environmental scope. The number of oil spills in water slide has increased significantly in recent years. Considering the complexity of the marine environment, the present work aims to apply a identification system of the dynamics and dispersion of oil, using the numerical modeling in the region of Franceses Bridge, near to Patos Lagoon-RS, Brazil. The study of hypothetical events of oil leakage in the region is of fundamental importance, since the Riograndense Petroleum Refinery is located inside of the Patos Lagoon estuary. A data structure of atmospheric and oceanic circulation was organized and inserted in the coupling between the hydrodynamic module Telemac-3D and the ECOS oil model, during the period between 2010 and 2013. The coupling of these models provided satisfactory results, requiring a level of computational effort favorable to obtaining of results capable of giving technical and scientific support to studies such as those of environmental impacts and contingency plans.

MID TERM SIMULATION OF SUSPENDED SEDIMENT TRANSPORT AND BED EVOLUTION FOR THE PATOS LAGOON ESTUARY

Worldwide harbors are settled inside estuarine areas due the protection function of these environments against oceanic waves and therefore are subjected to the hydrodynamic processes that provide morphodynamic changes in sediment distribution and bed evolution. Understanding the dynamic of sediments and the bed evolution at estuaries is of crucial importance on maintenance of fairways and harbor docks. We modeled using the finite element technique 1005 days of hydro and morphodynamic of the Patos Lagoon estuary, in order to identify the critical deposition areas inside the Rio grande harbor fairway. Therefore, a hydrodynamic model, TELEMAC 3D, and a morphodynamic, Sisyphe, were applied in order to acquire the bed evolution and sediment distribution of the area using different data sources for the oceanic, atmospherical and continental boundary conditions. The results, present that clay is being deposited at deeper parts of the channel. Bed evolution results indicate siltation/erosion process where silt/clay is being deposited. Sedimentation rates were calculated based on the bed evolution results as well. The validation procedure showed good representation by the models of the physical aspects of the environment.

Numerical study of oil spill in the Franceses Bridge region, Patos Lagoon estuary

The consumption pattern of the world population is based on derivatives petroleum, which despite contributing to the improvement of the quality of life, has negative aspects, mainly in the environmental scope. The number of oil spills in water slide has increased significantly in recent years. Considering the complexity of the marine environment, the present work aims to apply a identification system of the dynamics and dispersion of oil, using the numerical modeling in the region of Franceses Bridge, near to Patos Lagoon-RS, Brazil. The study of hypothetical events of oil leakage in the region is of fundamental importance, since the Riograndense Petroleum Refinery is located inside of the Patos Lagoon estuary. A data structure of atmospheric and oceanic circulation was organized and inserted in the coupling between the hydrodynamic module Telemac-3D and the ECOS oil model, during the period between 2010 and 2013. The coupling of these models gave a good approximation to the solution of the problem, besides demanding a level of computational effort propitious to obtaining results capable of giving technical and scientific support to studies such as those of environmental impacts and contingency plans.