A carregar...
2 resultados
Resultados da pesquisa
A mostrar 1 - 2 de 2
- Neoichnology and sediment distribution in tidal flats of the mud‐dominated mesotidal mira river estuary (Portugal)Publication . Shchepetkina, Alina; Drago, Teresa; Santos, Jacqueline; Alberto, Ana; Fatela, Francisco; Freitas, Maria da ConceiçãoInvertebrate burrow morphologies and distributions are presented for the tidal flats of the middle and lower reaches of the tide-influenced (mesotidal), mud-dominated Mira River estuary (SW Portugal) as an analogue for interpreting the ichnology of palaeoestuarine successions. Burrow distributions are revealed using field observations of biogenic and physical sedimentary structures, trace makers, collected grab samples, push cores and lab measurements of grain size, organic matter and calcium carbonate content and linked to physico-chemical stresses. Estuarine tidal-flat surface open burrow distribution and bioturbation intensity are analysed in plan view using free scientific image analysis software (ImageJ) to obtain burrow density, total burrow area and minimum and maximum burrow diameters. The total tidal flat area occupied by organisms ranges from 0.8% to 4.1% in the middle estuary and is 1.4% in the lower estuary. These equate to a bioturbation index of one to two (BI 1–2). However, computed tomography (CT) of push cores (cross-sectional view) taken on the same tidal flats shows sparse to complete bioturbation intensity (BI 1–6), revealing that tidal flat sediments tend to be more biogenically reworked cumulatively over time with overprinting of subsequent tiers and/or recolonized. CT scanning also allows the identification of more burrow types, demonstrates infaunal tiering and provides insights into trace-fossil preservation potential. This research shows that the trace communities are heterogeneous and change spatially and temporally along the Mira River estuary, reflecting a physico-chemical gradient and seasonality. This trend signals changes in sediment composition, substrate type and consistency (sediment compaction and subaerial exposure), salinity, oxygenation, temperature, pH and interplay of tidal versus hydraulic energy.
- Scanning the horizon: anticipating future changes in Portuguese aquatic ecosystemsPublication . Sousa, Ronaldo; Ferreira, Verónica; Costas, Susana; Alves, Celso; Anastácio, Pedro; Chaínho, Paula; Costa, Pedro A.; Duarte, Sofia; Feio, Maria João; Franco, João N.; Gonçalves, José; Ribeiro, Filipe; Robalo, Joana I.; Rivaes, Rui; Santos, Jacqueline; Silva, Janine; Sobral, Paula; Padilha, JaneideWe identified 15 emerging and poorly understood topics related to aquatic ecosystems in Portugal (from an initial pool of 43), which were scored and prioritized using a consensus-based Delphi technique. For marine ecosystems, the topics included current and future threats to low-lying sandy coasts, the impacts of the green energy transition, the risks posed by pathogens on floating ocean debris, the strategic importance of algae for a sustainable future, and Portugal’s potential contribution to the expansion of Marine Protected Areas. For freshwater ecosystems, the topics included identifying drought refuges for freshwater biodiversity, assessing the potential ecological and social costs of water highways, uncovering the hidden impacts of clean energy (floating solar panels and lithium mining), managing water quality in reservoirs, and understanding the potential impacts of the recent expansion of intensive olive orchards. For cross-cutting topics relevant to both types of ecosystems, the most scored topics included the importance of aquatic super-sites for ecological monitoring, new solutions for detecting and removing emerging pollutants, the application of rewilding, the impact of forest pathogens and emerging zoonoses, and the rise of organic compounds as a multidimensional threat. Prioritizing these topics can support a more proactive approach to conserving, managing, and sustainably exploring aquatic ecosystems in Portugal. This methodology can also be used to prioritize research funding areas identified bottom up (by the scientific community) rather than dictated from the top down (by decision-makers) and serve as a roadmap for conducting similar exercises in other regions of the world.