José Henrique Muelbert

Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

Whitemouth croaker, Micropogonias furnieri, trapped in a freshwater coastal lagoon: a natural comparison of freshwater and marine influences on otolith chemistry

Strontium and barium incorporation into otoliths was compared between whitemouth croaker, Micropogonias furnieri, collected from an entrapped freshwater population (Mirim Lagoon) and a normal marine/estuarine population in southern Brazil. Chemical analysis was performed using LA-ICPMS with the objective of validating the effects of marine and freshwater environments on Sr and Ba incorporation as a basis for further investigation of marine and freshwater connectivity of M. furnieri. The freshwater population was dominated by older fish with mean ±SD age of 34±1 y, whereas the coastal samples were dominated by younger fish of 14±7 y. Comparison of strontium and barium incorporation among otolith life-history profiles indicated significantly higher barium and lower strontium for the freshwater population compared to the marine population. Furthermore, comparison of otolith material deposited in the freshwater, estuarine and marine life-history phases demonstrated clear differences among these environments. Mean concentrations of strontium and barium in otoliths of M. furnieri were respectively 710 and 112 µg g-1 for freshwater, 2069 and 16.7 µg g-1 for estuarine, and 2990 and 2.7 µg g-1 for marine life-history phases. Barium concentrations in otoliths from the freshwater population of M. furnieri appeared high relative to other freshwater species. Strontium levels across life-history profiles of marine fish increased with age from 2000 to 2900 µg g-1, possibly indicating more time spent in marine than estuarine waters with age. In contrast, for the freshwater population, strontium levels decreased during the first year of life approximately to 700 µg g-1, and remained low and stable thereafter, consistent with the early life-history occurring in an estuarine environment prior to entrapment in Mirim Lagoon. The results confirm the strong and opposite effects of marine and freshwater environments on incorporation of barium and strontium into otoliths, and indicate that the population of M. furnieri in Mirim Lagoon represents an isolated population that does not reproduce and is therefore likely to become extinct.

Enhancing the Global Ocean Observing System to meet evidence based needs for the ecosystem‐based management of coastal ecosystem services

Ecosystem-based approaches (EBAs) to managing anthropogenic pressures on ecosystems, adapting to changes in ecosystem states (indicators of ecosystem health), and mitigating the impacts of state changes on ecosystem services are needed for sustainable development. EBAs are informed by integrated ecosystem assessments (IEAs) that must be compiled and updated frequently for EBAs to be effective. Frequently updated IEAs depend on the sustained provision of data and information on pressures, state changes, and impacts of state changes on services. Nowhere is this truer than in the coastal zone, where people and ecosystem services are concentrated and where anthropogenic pressures converge. This study identifies the essential indicator variables required for the sustained provision of frequently updated IEAs, and offers an approach to establishing a global network of coastal observations within the framework of the Global Ocean Observing System. The need for and challenges of capacity-building are highlighted, and examples are given of current programmes that could contribute to the implementation of a coastal ocean observing system of systems on a global scale. This illustrates the need for new approaches to ocean governance that can achieve coordinated integration of existing programmes and technologies as a first step towards this goal.

Dealing with temporal variation and different life stages of whitemouth croaker Micropogonias furnieri (Actinopterygii, Sciaenidae) in species distribution modeling to improve essential estuarine fish habitat identification

Understanding the habitat usage of a species is essential to assessing the impacts of human activities, conservation efforts, and management issues on that species. Whitemouth croaker, an important species in the artisanal fishery market, inhabits different habitats of the Patos Lagoon estuary year-round based on the stage of its life cycle. Our aim was to test the hypothesis that habitat preferences and changes in abundance during the life cycle influence the model outcomes in the study of species distribution. Additionally, we evaluated whether incorporating additional life stages within the model affected the outcome of what comprised the essential fish habitat. Our results showed that the model’s outcome was affected when temporal variability and additional life stages were considered. We suggest that variability in abundance and habitat preferences at different developmental stages must be considered when identifying essential fish habitat of species with complex life cycles, such as whitemouth croaker. Understanding these changes could improve conservation and management outcomes.

Biota of the Patos Lagoon Estuary and Adjacent Marine Coast: Long-term Changes Induced by Natural and Human-related Factors

In this Thematic Issue (TI) we present new results obtained in the framework of the Brazilian Long Term Ecological Research (BR-LTER) Programme for the Patos Lagoon estuary (PLE) and the adjacent marine coast in southern Brazil. The BR-LTER was established in 1997 and the rationale for the conception and delineation of the initial projects was based on previous knowledge of the ecosystems. Since the end of the nineteenth century, the high biological productivity and ecological complexity together with human interference have been recognized in the PLE (Von Ihering 1885). The favourable natural conditions promoted the development and led to the increased importance of economic activities associated with fisheries, the harbour and industrial growth up to the present time. In 1978, the Oceanography Base (currently the Institute of Oceanography) was established at the Federal University of Rio Grande, and since then biological and oceanographic systematic studies have been conducted in the estuary and on the continental shelf. Seeliger et al. (1997) synthesized results gathered over almost 20 years, and now we can present the state-ofthe-art science on long-term changes induced by the natural and human-related factors in the PLE and the adjacent marine coast. It is widely recognized that long-term information in subtropical and tropical environments, specifically, is deficient in the southern hemisphere and this represents a caveat that limits the achievement of a global synthesis about the biological variability and dynamics of aquatic ecosystems. Our purpose with this TI is to provide information on the long-term ecology of a coastal ecosystem located in the subtropical region of the southern hemisphere, at latitude 32°S, considering different components of the complex food web in this ecosystem. In the present issue, 10 original articles and one review article evaluate the mesoscale and long-term variability of primary producers such as microand macroalgae, consumers of low (e.g. zooplankton, ichthyoplankton, pink-shrimp, fishes) to high (fishes, birds, marine mammals) trophic levels and the effects of fisheries on the abundance and population dynamics of exploited species in the PLE and the adjacent marine coast. Altogether, this unprecedented information points to the importance of the large-scale climatic phenomenon El Niño Southern Oscillation (ENSO) on the functioning of the estuarine ecosystem, and contributes to the prediction of possible responses to future climate changes and to the conservation of coastal ecosystems. Moreover, it was observed that human-induced impacts played an important role in changing the community structure and dynamics in this environment. This information provides a better understanding of a complex coastal ecosystem in the southern hemisphere, and therefore helps to form consistent scenarios and hypotheses of the functioning of coastal ecosystems around the world. The Patos Lagoon (10,360 km) is the receptor of an extensive watershed, the Patos-Mirim Lagoon system (≅ 200,000 km) shared between southeastern Brazil and northeastern Uruguay in subtropical eastern South America. Due to the positive rainfall–evaporation water balance in the large watershed area, the larger part of the Patos Lagoon is predominantly fresh to oligohaline, with a high sediment load (Möller et al. 1996; Odebrecht et al. 2005). The estuarine region, with an area of 900 km, is located in the southernmost part of the Patos Lagoon. Most of the estuary (≅ 90%) is shallow, with a depth less than 2 m (Figure 1). Water exchange between the estuary and the coastal region occurs through a narrow channel and fluxes are mainly controlled by wind and rainfall, because tides are of small amplitude (40 cm). The adjacent marine coast presents a gentle slope and wide continental shelf, and it is strongly influenced by freshwater run-off from the Patos Lagoon and Rio de La Plata (Ciotti et al. 1995; Campos et al. 2008; Pimenta & Kirwan 2014). The oceanic beaches in this region are intermediate to dissipative with regard to wave energy and are characterized by the accumulation of surf-zone diatoms that produce an enormous biomass, especially following the passage of atmospheric fronts (Odebrecht et al. 2010a). In the PLE, the primary producers are phytoplankton, benthic microand macroalgae and seagrasses, and they guarantee an important carbon contribution to the very productive food web, resulting in important fishery activities in the estuary and adjacent marine coast. The availability of light and nitrogen nutrients, but also predation, influences the estuarine primary producers. However, meteorological and hydrological forces such as the action of winds and rainfall cause most of the variability observed in the short, medium and long timescales. It was observed that the remote phenomenon ENSO strongly influences interannual variability of planktonic

Ichthyoplankton Associated to the Frontal Regions of the Southwestern Atlantic

The study region covers a wide latitudinal range, from 22°S to 55°S, and a bathymetric scope ranging from the coast to the shelf-break and adjacent region to a depth of ca. 1000 m. Hydrography of the region is extremely complex. Oceanographic structures are diverse, including several estuaries, water masses, wind systems, tidal regimes, and two major oceanic currents. A significant portion of the biological production is related to the existence of several marine fronts, characterized by different forcing, and temporal and spatial scales. Fish species that inhabit the region are diverse, covering a range of life strategies. Among those fishes that produce eggs and/or planktonic larvae, there are estuarine, shelf and oceanic forms, and species characteristic of tropical/subtropical or subantarctic waters. Pelagic species are more important in the northern part, while demersal species dominate the southernmost area. The region looks like an intricate mosaic of opportunities for life cycle closure of distinct species. Marine fronts seem to be the preferred areas to establish spawning and nursery grounds by fishes, and current knowledge allow to identify the elements of Bakun’s triad for several of those fronts.

Environmental Variability and Cyanobacterial Blooms in a Subtropical Coastal Lagoon: Searching for a Sign of Climate Change Effects

Cyanobacterial blooms in marine and freshwater environments may be favored by shifts in physical water column parameters due to warming under climate change. The Patos Lagoon (PL), a subtropical coastal environment in southern Brazil, is known for recurrent blooms of Microcystis aeruginosa complex (MAC). Here, we analyze the variability of these blooms and their relation to changes in wind direction and speed, rainfall and freshwater run-off from 2000 to 2017. Also, we discuss both longer time-series of air temperature and rainfall and a review of local studies with microcystins produced by these noxious species. Since the 1980s, MAC blooms were associated to negative anomalies in annual precipitation that occur during La Niña periods and, in the last years (2001–2014), accompanied by a trend in low river discharge. MAC blooms were conspicuous from December to March, i.e., austral summer, with massive patches seen in satellite images as for 2017. We suggest that low rainfall and run-off years under NE wind-driven hydrodynamics might accumulate MAC biomass in the west margin of the PL system. In contrast, a positive, long-term trend in precipitation (from 1950 to 2016; slope = 3.9868 mm/yr, p < 0.05) should imply in high river discharge and, consequently, advection of this biomass to the adjacent coastal region. Due to the proximity to urban areas, the blooms can represent recreational and economic hazards to the region.

Efficiently enforcing artisanal fisheries to protect estuarine biodiversity

Artisanal fisheries support millions of livelihoods worldwide, yet ineffective enforcement can allow for continued environmental degradation due to overexploitation. Here, we use spatial planning to design an enforcement strategy for a pre-existing spatial closure for artisanal fisheries considering climate variability, existing seasonal fishing closures, representative conservation targets and enforcement costs. We calculated enforcement cost in three ways, based on different assumptions about who could be responsible for monitoring the fishery. We applied this approach in the Patos Lagoon estuary (Brazil), where we found three important results. First, spatial priorities for enforcement were similar under different climate scenarios. Second, we found that the cost and percentage of area enforced varied among scenarios tested by the conservation planning analysis, with only a modest increase in budget needed to incorporate climate variability. Third, we found that spatial priorities for enforcement depend on whether enforcement is carried out by a central authority or by the community itself. Here, we demonstrated a method that can be used to efficiently design enforcement plans, resulting in the conservation of biodiversity and estuarine resources. Also, cost of enforcement can be potentially reduced when fishers are empowered to enforce management within their fishing grounds.