Estuaries and Coasts最新文献

Estuarine and adjacent inshore habitats have long been recognised as important nursery areas for fishes before they disperse to coastal habitats. Assessing nursery function supports spatial and fisheries management, yet work commonly focusses on singular habitat types. Re-considering how juvenile fish connect habitats may improve our understanding of nursery function and the scales that recruits are supplied to coastal fisheries. This study quantified the juvenile movements of two harvested fishes in south-eastern Australia, luderick (Girella tricuspidata) and yellowfin bream (Acanthopagrus australis). Acoustic tags were used to track 33 luderick and 20 yellowfin bream from seagrass meadows for up to ~400 days in Jervis Bay Marine Park. Both species had relatively small home ranges (< 7 km²) and exhibited site attachment to seagrass meadows where they were released. Most luderick and yellowfin bream were detected moving 100’s metres to kilometres to reefs adjacent to seagrass, although these movements were not habitat shifts. Rather, reef-ward movements represented repeated visits that lasted days to months before fish returned to seagrass, suggesting that these movements may be explorations in search of suitable adult habitat. Strong retention within an existing marine reserve was observed, with only five of 33 fish tagged within reserves crossing the boundary into fished waters. Overall, our results demonstrate that juvenile fish use and connect multiple habitat types during their movements. These findings support the broadening of the nursery concept from single habitats to a mosaic of functionally connected habitat patches (dubbed ‘seascape nurseries’).

Coastal wetlands surrounding urban environments provide many important ecosystem services including protection from coastal erosion, soil carbon sequestration and habitat for marine and terrestrial fauna. Their persistence with sea-level rise depends upon their capacity to increase their soil surface elevation at a rate comparable to the rate of sea-level rise. Both sediment and organic matter from plant growth contribute to gains in soil surface elevation, but the importance of these components varies among sites and with variation in climate over long time scales, for which monitoring is seldom available. Here, we analysed variation in surface elevation, surface accretion and mangrove tree growth over 15 years in Moreton Bay, Queensland, Australia, a period that spans variation in the El Niño/La Niña (ENSO) cycle, which strongly influences rainfall and sea level in the region. Piecewise structural equation models were used to assess the effects of biotic (tree growth, plant cover and bioturbation by invertebrates) and environmental factors on annual surface elevation increments throughout this period. Our model for mangroves identified that surface accretion and tree growth were both positively influenced by rainfall, but surface elevation was not, and thus, higher levels of compaction of the soil profile in high rainfall/high sea level years were inferred. In contrast, our saltmarsh model found that rainfall positively influenced surface accretion and elevation gains. Declines in surface elevation in the mangroves were influenced by the species composition of the mangrove, with higher levels of elevation loss occurring in mangrove forests dominated by Avicennia marina compared to those with a higher proportion of Rhizophora stylosa. Decadal-scale variation in ENSO affected mangrove tree growth, but surface elevation trends were more strongly influenced by variation in environmental conditions than by tree growth, although effects of biotic factors (mangrove species composition and bioturbation) on surface elevation trends were observed. Further research into tipping points with extreme ENSO events (either La Niña with high rainfall and high sea level or El Niño with low rainfall and low sea levels) will help clarify the future of mangrove and saltmarsh distribution within Moreton Bay.

A network of 15 Surface Elevation Tables (SETs) at North Inlet estuary, South Carolina, has been monitored on annual or monthly time scales beginning from 1990 to 1996 and continuing through 2022. Of 73 time series in control plots, 12 had elevation gains equal to or exceeding the local rate of sea-level rise (SLR, 0.34 cm/year). Rising marsh elevation in North Inlet is dominated by organic production and, we hypothesize, is proportional to net ecosystem production. The rate of elevation gain was 0.47 cm/year in plots experimentally fertilized for 10 years with N&P compared to nearby control plots that have gained 0.1 cm/year in 26 years. The excess gains and losses of elevation in fertilized plots were accounted for by changes in belowground biomass and turnover. This is supported by bioassay experiments in marsh organs where at age 2 the belowground biomass of fertilized S. alterniflora plants was increasing by 1,994 g m⁻² year⁻¹, which added a growth premium of 2.4 cm/year to elevation gain. This was contrasted with the net belowground growth of 746 g m⁻² year⁻¹ in controls, which can add 0.89 cm/year to elevation. Root biomass density was greater in the fertilized bioassay treatments than in controls, plateauing at about 1,374 g m⁻² and 472 g m⁻², respectively. Growth of belowground biomass was dominated by rhizomes, which grew to 3,648 g m⁻² in the fertilized treatments after 3 years and 1,439 g m⁻² in the control treatments after 5 years. Depositional wetlands are limited by an exogenous supply of mineral sediment, whereas marshes like North Inlet could be classified as autonomous because they depend on in situ organic production to maintain elevation. Autonomous wetlands are more vulnerable to SLR because their elevation gains are constrained ultimately by photosynthetic efficiency.

Shallow coastal systems act as nursery habitat for many species of fish and macroinvertebrates. Juveniles of these species may show selective use of certain habitat types over others, but the degree of such selectivity is not well studied for many species. Analysis of habitat selectivity is often hindered by inherently different gear types used in the habitats examined, which may not allow for direct comparison between the habitats. Here, we carry out nekton catches in the fringing marsh, using fyke nets, and in the adjacent seagrass habitat, using trawls, in the northern Gulf of Mexico to assess the relative use of the two habitats by the juveniles of six widespread important species. To resolve issues of gear comparability between fyke nets and trawls, we develop a habitat use index (({HUI}_{S})). The results reveal a consistent trend where, in relation to pinfish, speckled sea trout shows slightly higher (from 8.4 to 66.9 times); American silver perch and brown shrimp show moderately higher (from 2.3 to 369.4 times); and blue crab and white shrimp show greatly higher (from 90.6 to 2366.4 times) use of marsh over seagrass habitat. Thus, while similar in direction, differences in the use of marsh over seagrass habitat in relation to pinfish were more pronounced in some sites. We propose an index that can resolve issues of gear comparability and improve our understanding of coastal habitat selectivity by fish and macroinvertebrates.

Abstract

Some hydrozoan species are known for their high adaptability and dormancy ability, e.g., Cladonema species, which are also promising model organisms. Since salinity affects the development and distribution of hydrozoan species, it is important to get further understanding of salinity tolerance and dormancy ability of Cladonema species. Cladonema digitatum is a cryptic species and is discovered only in artificial environments. In this study, multiple experiments have been conducted to determine how salinity affects the development of C. digitatum polyps and medusae, to describe the dormancy and recovery of the C. digitatum polyps, and to find the possible prevention and disposal protocol for the occurrence of Cladonema in artificial environments. As results, salinity range of 35–40 ppt was optimal for C. digitatum polyps, while C. digitatum medusae lived best in 30–35 ppt; C. digitatum would form menonts at 15, 50–60 ppt, revive and change their survival strategies after salinity upturned to 35 ppt, which could enhance their tolerance and adaptability. Cladonema digitatum medusae also showed different death rates when faced with sharp hypersaline and hyposaline stress. In summary, this research provided ecological information about salinity range and dormancy ability of C. digitatum, which not only facilitated tracing the wild habitats of the C. digitatum, but also provided the theoretical basic of elimination and prevention of Cladonema species intrusion and breeding conservation in the laboratory.

Here, we present a point-by-point response to the unfounded and unsupported criticisms presented in the Technical Commentary, “Red Drum Salinity Tolerance: Comments on Ackerly et al. “Short-Term Salinity Stress During Early Development Impacts the Growth and Survival of Red Drum (Sciaenops ocellatus)” by Conway et al. (2023). The technical commentary – which was not subject to the same peer review process as the article it attempts to undermine – was written by consultants that were paid by an industrial entity that has invested heavily in multiple proposed desalination projects sited within an enclosed bay system. Here, we provide additional detail on Conway et al.’s conflict of interest and demonstrate that their arguments are fundamentally flawed and – in many cases – conflict with one another. We conclude that the intentions underlying Conway et al.’s criticisms are to undermine confidence in credible peer-reviewed science, and to attempt to establish a basis for future legal arguments regarding contested permits for desalination facilities within essential fish habitat. Ultimately, the assertions in Conway et al. (2023) are not intended to be convincing to the larger scientific community, but to muddy the waters for legal experts and decision makers that lack expertise in ecotoxicology.

Araruama Lagoon is one of the world’s largest permanent hypersaline lagoons, and knowledge about the reproduction of fish assemblages is very scarce. This study aimed to evaluate the reproductive functionality of fishes of the Araruama Lagoon in the seasons of 2011, using functional diversity metrics. We also assessed the influence of abiotic factors (salinity, temperature, dissolved oxygen, and pH) on the distribution of sexes and reproductive stages of fish assemblages. Gonads were analyzed in 709 fish across 18 species, mainly females and juveniles. In winter, when there was a lower abundance of species, the highest reproductive incidence (gonadal development/maturation) and high salinity occurred. Summer and spring corresponded with the highest percentage of juveniles. Salinity was the abiotic factor behind the structuring of the community, while the temperature set off the start of the reproductive cycle in autumn. Thus, Araruama Lagoon played a crucial role as a nursery and reproductive area for the fish assemblage.

Graphical Abstract

Reproduction in Araruama Lagoon (2011). The vertical arrows indicate the main abiotic variables: temperature and salinity, which structure the fish community. Colors indicate larger (darker) and smaller (lighter) numerical values. The graphs show the percentage of juveniles, males and females, in the seasons corresponding to each season: spring (green), summer (yellow), autumn (orange), and winter (gray). The number of fish next to each graph indicates fish abundance in season, and fish colors indicate diversity.

The impact of urban and agricultural development on sediment quality in the Alvarado Lagoon region in the southern Gulf of Mexico requires an examination of the historical behavior of potential toxic metals (PTMs) and polycyclic aromatic hydrocarbons (PAHs). Consequently, this study aims to assess the ecotoxicological hazards that benthic species and human consumers face in the area. These results are crucial for economic activities in the region and can help prevent future hazards. We examined two sediment profiles from the ecosystem: Profile 1, which spans the period between 1929 and 1998, and Profile 2, which covers the years between 1929 and 2007. The study evaluated the degree of human-induced pollution of six trace metal elements (PTMs): arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), and vanadium (V) in the sediments of Alvarado Lagoon. The Enrichment Factor (EF) and Geoaccumulation Index (I_Geo) were computed as internationally recognized indices to measure the magnitude of contamination and additional anthropogenic and geochemical inputs contributing to the natural levels of the elements. Our analysis indicates that there is no evidence of either enrichment or pollution (EF < 1 class 1; I_Geo < 0 class zero) found in the sediments of Alvarado Lagoon. The occurrence of these elements can be attributed to their lithogenic origin, as supported by a significant correlation observed between them. Within the 16 polycyclic aromatic hydrocarbons (PAHs) analyzed, solely Naphthalene (Nap) and Phenanthrene (Phe) were identified in both sediment profiles. The levels of chemicals are indicative of minimal ecotoxicological risks, with Nap ranging between 0.25 and 0.43 µg g⁻¹ and Phe ranging between 0.31 and 0.79 µg g⁻¹. The analysis of factors in this study identified two distinct factors, one related to lithogenic processes and another related to petrogenic processes. The sedimentary profiles of the study site confirmed low levels of potentially toxic metals and polycyclic aromatic hydrocarbons (PAHs), posing insignificant environmental risks. As a result, the ecosystem in this area has demonstrated resilience.