THIRTY-FIVE YEARS OF ZOOPLANKTON STUDIES IN A TROPICAL ESTUARINE ECOSYSTEM: WHAT IS COMING NEXT?

Estuarine food web structure and relative importance of organic matter sources for fish in a highly connected Northeastern Brazil ecotone

Effect of fishing effort on the trophic functioning of tropical estuaries in Brazil

Studies were carried out on the Inlets of Orange and Catuama at the Santa Cruz Channel, Itamaracá-PE, in the rainy and dry seasons, in a nyctemeral cycle, and in a transversal profile, with intervals of three hours between collections. The objective was to determine the spacial and temporal variation of the N:Si:P atomic ratio, and its possible inter-relations and dependencies, as well as the influence of the hydrodynamism provoked by the variation of the tides at different times of the year. Nitrite-N and nitrate-N were higher in the rainy season, while ammonia-N, phosphate-P and silicate-Si were higher in the dry season, which indicated different results than previous studies. The N:P atomic ratio was lower than 16:1, in all seasons and stations, being highest in the rainy season at Inlet Orange. The Si:P atomic ratio was always high. During the observed nyctemeral cycles, the main factors influencing the composition of the physical, chemical and biological parameters were the tide cycles and the meteorological parameters.

The objective of this study was to quantify the zooplankton biomass transport between the Santa Cruz Channel (SCC) at Catuama north inlet and the adjacent shelf located in Itamaracá estuarine ecosystem, Pernambuco State, Northeastern Brazil. Sampling was carried out in August 2001 at spring and neap tides at three stations every 3-hour interval. Collections were made in three depths with a plankton pump coupled to a 300 µm mesh size net. Current data were obtained with an ADCP (Acoustic Doppler Current Profiler). In laboratory, samples were filtered for wet weigh determination. High biomass variation was recorded, with highest values at nocturnal flood and ebb during spring tide. The average instantaneous biomass transport was 139.48 ± 72.58 mg.m-2s-1, during spring tide and 36.63 ± 27.66 mg.m-2s-1, during neap tide. No significant difference was registered between importation and exportation flows (p > 0.05), showing that the estuary both exports and imports high biomass during the rainy season. It can be concluded that the outwelling at SCC is high, however, differently from other places, importation is also high, probably due to the presence of reefs and patches of seagrass (Halodule wrightii) toward the shelf that create a distinct productive environment.

The aim of this study was to analyze reproductive aspects of Callinectes danae in one of the most productive estuarine systems in the Northeast Brazil, Santa Cruz Channel. A total of 1.573 individuals, being 756 females (23 ovigerous) and 817 males were examined from January to December 2009. Mature males and females, as well as couples of C. danae, occurred in all months of the year. Ovigerous females occurred in nearly all months. The reproductive activity, based on the macroscopic observation of the gonads, occurs continuously, with distinguishable peaks in February, March and September. Ovigerous females were only recorded nearest to the sea, while couples were only in the inner estuary. Thus, a migration pattern is proposed, with couples mating inside the estuary, followed by a migration of females to the area of greater marine influence for egg laying and, probably, larval release. After this, probably the females of do not return to the estuary, characterizing habitat partitioning. The present study is the first contribution on the reproductive period of C. danae in an estuarine ecosystem of the Brazilian northeast coast, and elucidates some aspects of its reproductive behavior.

The Santa Cruz Channel is located in the Estuarine Complex of Itamaraca, between the coordinates of 7°34’00’’ – 7°55’16’’S and 34°48’48’’ – 34°54’24’’W, northeast of Brazil. This channel is one of the most important productive areas of the littoral zone in the Pernambuco State. Due to the important environmental conditions, its phycological flora diversity is represented by 252 species, distributed in 108 Bacillariophyta, 80 Rhodophyta, 19 Phaeophyta and 45 Chlorophyta. Some representatives of economic value are found, such as Hypnea musciformis (Wulfen in Jacquin) J. V. Lamour., Solieria filiformis (Kuetz.) P. W. Gabrielson (carrageenan producers), Gracilariopsis lemaneiformis (Bory) Dawson, Acleto et Foldvik. Hydropuntia caudata (J. Agardh) Gurgel & Fredericq and H. cornea (J. Agardh) M. J. Wynne (agar producers). Other species, like H. opuntia (L.) J.V. Lamour, have a high ecological role in the reef bottom.

Copepod carcasses and non‐predatory mortality can occur due to natural senescence, disease, pollution, and physicochemical stress. Our objective is to evaluate and characterize the rates of non‐predatory mortality and the contribution of zooplankton community carcasses, represented by the copepods, in tropical estuarine ecosystems with different degrees of urbanization. During the study, there was a significant difference between environments and copepod carcasses, with Suape Bay (moderately urbanized) being the environment with the highest abundance of adult copepod carcasses (93.3%). The average non‐predatory mortality rate of adult copepods was 0.15 day−1: Santa Cruz Channel (sparsely urbanized) contributed the lowest values, with a mortality rate of 0.01 day−1, and Suape (moderately urbanized) had the highest rate (2.80 day−1). The families Paracalanidae (0.554 day−1) and Oithonidae (0.122 day−1) had the highest values, with an average carcass decomposition of 4.7 days. Among the environments studied, there was little differentiation between carcass percentages and mortality rate, not supporting the hypothesis that the higher rates of mortality among non‐predatory copepods were related to large urban centers. However, there was an almost proportional contribution of carcasses and non‐predatory mortality in all but a few areas, agreeing with the hypothesis that there is spatial variation with respect to carcasses in tropical estuaries. With our work, we show that estuaries can provide the estuarine food web with a significant portion of copepod carcasses, which may vary by family, and that it is not necessarily environments with a higher degree of urbanization that will have higher mortality rates.

Transport processes in the Santa Cruz Channel, Brazil

As seletividades de redes de emalhar para peixes forrageiros que habitam o Canal de Santa Cruz (PE, Brasil) foram estimadas a partir de um experimento com três tamanhos de malha (30, 40 e 50 mm). O SELECT foi usado para estimar as curvas de retenção através de quatro modelos: normal com dispersão fixa, normal com dispersão variável, lognormal e gama. No total foram identificadas 28 espécies. Os parí­¢metros de seletividade foram estimados para as espécies Opisthonema oglinum, Anchovia clupeoides e Cetengraulis edentulus. O modelo normal com dispersão variável foi de melhor ajuste para todas as espécies. No caso da pesca da O. oglinum no Canal de Santa Cruz verificou-se que as quantidades capturadas de indiví­­duos jovens são particularmente mais expressivas na rede de emalhar com a malha de 30 mm. No entanto, um eventual aumento da malha indica um desvio pouco significativo da estrutura de comprimento da captura para maiores tamanhos, mas as capturas certamente seriam reduzidas. Assim, regulamentações com aumento de malha devem resultar em inviabilidade da continuidade da pesca com diminuição das capturas.

This study evaluated trace metal pollution in sediments and fishes from two tropical estuarine systems in Northeast Brazil: the Santa Cruz Channel Estuary (ITAP) and the Sirinhaém River Estuary (SIR). An integrative approach combining several environmental and toxicological assessment indices was employed. In general, concentrations of trace metals in sediments-including cadmium (Cd), chromium (Cr), lead (Pb), and zinc (Zn) in ITAP and Cd, Cr, Pb, Zn, and total mercury (THg) in SIR-were below the Threshold Effect Levels (TEL), suggesting a low likelihood of adverse effects on benthic biota. However, elevated THg concentrations exceeding the Probable Effect Levels (PEL) were observed at specific sites within the ITAP system, indicating a high potential for ecological harm. Environmental quality indices identified THg and Copper (Cu) pollution in ITAP and Cu pollution in both estuaries. Ecological risk and Nemerow multi-factor indices suggested that SIR is subject to low ecological risk, with Cu being the dominant pollutant. In contrast, ITAP exhibited high ecological risk driven primarily by Cu and THg. Among the species examined, Bairdiella ronchus and Centropomus undecimalis, which are frequently consumed by local populations in ITAP, exhibited Hg concentrations exceeding established safety thresholds for human consumption. The application of multiple assessment indices provided a comprehensive understanding of environmental degradation caused by anthropogenic pressures, particularly in the Santa Cruz Channel. These findings underscore the need for effective public policy enforcement aimed at long-term pollution monitoring and safeguarding food security for local communities.

Martins, S. E. M; Barcellos, R. L; Flores-Montes, M. J. and França, E. J. 2016. Depositional evolution in a lagoonal estuarine system under a port influence in Northeastern Brazil. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 83–87. Coconut Creek (Florida), ISSN 0749-0208.The Holocene evolution reconstruction corroborates to understand sediment dynamics and, recent anthropogenic environmental changes; in addition, may subsidize the future prospects of its development. The aim of this work is to elaborate a historical comparative analysis of the total organic matter content (TOM), calcium carbonate (CaCO3) and grain size variation in a estuarine environment and adjacent inner shelf area under influence of Recife Port (8°03′S/34°53″W), Northeastern Brazil. Two sediment cores were collected (Jun/2013), one (1.26m long) in the inlet of the estuarine system (T2E); and another (1.30m long) in a sheltered area of a breakwater adjacent to the estuary mouth (T3E). The sedimentation rate, measured based on breakwater building (1909), was 1.18 cm.year−1 in T3E and 0.81 cm.year−1 in T2E. The cores presented preservation of structures indicative of waves and currents processes, such as erosive surfaces, linsen bedding, flaser bedding, and wavy bedding, environment features of shallow platform. Both cores presented variations in sediment composition with an essential carbonate sandy base ranging upward to a terrigenous mud on their tops. The change in sediment composition indicates environmental changes such as the increase in the sediment suspension concentrations, directly influenced by changes in coastal engineering in the Recife Port. The results indicate how important local rivers sediments input and estuarine processes are to deposition features in the estuarine lagoonal system, like the mud trapping and preservation in the inner shelf shallow areas adjacent to the Recife Port.

In northeastern Brazil (7°34′–7°55′ S and 34°48′–34°52′ W), the tropical Itamaracá estuary system (824 km2) was formed during the early Holocene. A fault which gave origin to the Santa Cruz Channel was flooded by seawater and connected with the South Atlantic Ocean by the Catuama and Orange entrance (Fig. 5.1). Offshore regions typically have a series of two or three parallel sandstone reefs (20–60 m wide) which consist of cemented sand (20–80% of quartz and biogenic detritus) and become exposed during low waters, as well as eight to ten permanently submerged reef lines (Mabesone 1964). Most of the exposed and submersed reefs were formed during Holocene sea level still-stands (Morais 1970) and some are still being formed. Remnant reefs on land were presumably formed during temporary still-stands of the Quaternary regression phase (Ottmann 1960). The discontinuous sandstone ridges, as well as reefs and sand banks north of the Catuama and south of the Orange entrance, form a semi-open elongated lagoon-like environment (“inner sea”) which restricts the exchange of water between the Santa Cruz Channel and offshore areas (Medeiros and Kjerfve 1993; Fig. 5.1).KeywordsRainy SeasonTotal Suspend SolidParticulate Organic CarbonMangrove AreaEstuarine EcosystemThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Blackfordia virginica, a hydromedusa native to the Black Sea, has become established in a number of estuarine areas worldwide. In estuaries of northeastern Brazil, only a single published report, from the early 1960s, exists of the species and its establishment here has remained doubtful. On discovering specimens collected in the region at various times between 1987 and 2000, however, we hypothesized that this hydromedusa has long inhabited estuaries in the area while going unnoticed. The objective of this study was to investigate its occurrence in brackish waters of tropical northeastern Brazil over the past 50 years. In a search for specimens we found 1,759 individuals from estuaries of the Santa Cruz Channel (Itamaracá) and Capibaribe and Jiquiá rivers that had been collected between 1987 and 2000. In addition, an analysis of grey literature (Ph.D. theses) suggests that the species has been present in the Santa Cruz Channel for at least five decades. Results thus support the hypothesis that this non-indigenous species has been established in the region for several decades at least, and that it constitutes an exotic component of the community.

Connectivity between the marine coast and estuary for white mullet (Mugil curema) in northeastern Brazil revealed by otolith Sr:Ca ratio

The present work aims to study the size vs. weight relationship and the condition factor of a commercially important crab, Callinectes danae, from an estuarine complex located at Pernambuco State, Northeastern Brazil. After sampled, the specimens were measured on their carapace width (CW; mm) and weighted on their wet weight (WW; g). A total of 1,635individuals of C. danae were analyzed, being 881 males (53.8%) and 754 females (46.2%). Males were significantly larger and heavier than females (p < 0.05), the expected pattern to many crabs. The relationship WW vs. CW, described through the potency equation, was allometrically positive for both males (b = 3.12) and females (b = 3.02), a result also observed in other swimming crabs. The mean condition factor of males was 8.0 10-5 ± 1.5 10-5, and that of females was 11.5 10-5 ± 2.8 10-5, being significantly higher in females (p < 0.05), due to the fact that female gonads are heavier than that of males. The condition factor oscillated throughout the sampling year, for both sexes, which was related to the reproductive cycle.