Marine Ecology-An Evolutionary Perspective最新文献

Monitoring changes in coral reef ecosystems for their conservation and management is important as they are frequently subject to various natural and anthropogenic threats. However, in Sri Lanka, the attention in this regard is to be further concerned for their well-being. Therefore, this study focused on the selected shallow water (<5 m) coral reefs as Pigeon Island (PIR), Adukkuparu (AR), Salli Beach (SBR), Kayankerni (KR), and Passikuda (PR) on the Eastern coast of Sri Lanka to estimate their changes over 2020, 2021, and 2022. The remote sensing demarcations with the composition of reef ecosystems were done through the analysis of the Allen Coral Atlas data followed by field surveys. Higher accuracy levels for corals were obtained for each site due to field verifying all individual polygons and omitting unmatched polygons of the initial maps from the Allen Coral Atlas. Then, the in-situ reef surveys were conducted over randomly selected permanent transects at each site. From 2020 to 2022, the live coral percentages have increased in PIR, AR, and SBR while reduced in KR and PR. Dead corals have facilitated the overgrowth of macroalgae. The combined area of live coral on all five reefs has slightly gone up. This increase is primarily due to the rise in live coral cover in AR and SBR. Also, prominent increments of coral diversity have resulted from those sites. Therefore, it is suggested that AR and SBR be designated as Marine Protected Areas to safeguard the newly emerging live corals.

In contrast to tropical and subtropical regions, where coral abundance is declining due to elevated summer seawater temperatures, expansions of coral ranges have been reported in temperate Japanese regions due to an increase in seawater temperature. However, the vulnerability of corals in temperate Japanese regions to elevated summer seawater temperatures is not well known. In this study, we assessed the bleaching state of corals with elevated seawater temperatures during summer in a temperate Japanese coastal sea around Takashima Island, using an underwear color reference card (Coral Health Chart). This study showed that the color of temperate corals turned pale with increasing seawater temperature during summer. However, the corals did not reach a bleached state. Approaching a typhoon may contribute to maintenance of coral health at Takashima Beach by mitigating high seawater temperatures during summer and preventing the accumulation of thermal stress in corals.

Surface phytoplankton community, abundance, and species spatial distributions were investigated in the Malacca Straits (MS) of Peninsular Malaysia during the late northeast monsoon (March) and southwest monsoon (August) in 2019 to understand factors controlling their community dynamics. This study reveals that the monsoonal transitions lead to changes in sea surface temperature (SST), sea surface salinity (SSS), total nitrogen (TN), total chlorophyll-a (Tchl-a), and phytoplankton density in the MS. A total of 204 and 163 phytoplankton species were identified during March and August, respectively, with diatoms representing the most (80.6%), followed by dinoflagellates (9.9%), cyanobacteria (8.3%), and others (1.2%). Meanwhile, the average total phytoplankton density was lower in March (10.78 × 10³ ± 14.70 cell L⁻¹) and greater in August (26.98 × 10³ ± 45.63 cell L⁻¹), with Chaetoceros compressus and Thalassiosira sp. Seven found the highest in each season, respectively. There was no significant correlation between phytoplankton density and environmental parameters in the MS, except for the cyanobacteria and dinoflagellate communities. However, the Canonical Correspondence Analysis results showed that environmental parameters such as SST, SSS, and nutrients in the MS could affect the dominant phytoplankton species, particularly diatoms. The findings suggest that environmental changes between the seasons may act as ecological drivers in the formation of phytoplankton communities in marine habitats of the MS.

Golf ball sponges are small, sometimes inconspicuous, sponges. They can be found across a range of habitats varying from perturbed and pristine coral reefs to harbours and marine lakes and from the deep sea to shallow waters. They can be difficult to distinguish in the field and have presented some problems with taxonomists lumping and splitting species due to the difficulty in defining clear species boundaries. In the present study, we sampled golf ball sponges from Indo-Pacific and Caribbean locations and used 16S gene amplicon sequencing to study their prokaryotic communities. We show that golf ball sponges harbour a wide variety of prokaryotic communities. Among the most prevalent operational taxonomic units (OTUs), several belonged to a range of taxa, including the bacterial AqS1 and EC94 groups, which have been associated with genes known to facilitate interactions between hosts and microbes. Certain host taxa were enriched with OTUs classified to the SAR202 clade of Chloroflexi. Our findings show that prokaryotic dissimilarity varied as a function of space (geographical distance) and host dissimilitude. The importance of space and host dissimilitude, however, varied depending on the data transformation with host dissimilitude a more important predictor of untransformed data whereas space was a more important predictor of log-transformed data. Given that log-transformation downscales the influence of abundant taxa, we interpret these results by the tendency of closely related host organisms to host similar sets of abundant symbiotic microorganisms; distantly sampled specimens, in contrast, tend to harbour less abundant prokaryotic microorganisms found in the surrounding environment (e.g., seawater or sediment).

Seagrass meadows provide essential ecosystem services but have been strongly declining over the past. Due to their incapability to recover effectively naturally, assisted restoration is used. This study aimed to test textile fabrics from natural derivatives to serve as carrier substrates for seagrass transplantation. The use of biotextile fabrics should enable seagrasses to better withstand hydrodynamic forces, especially in high-energy areas and during autumn and winter storms in the initial phase of restoration, thereby increasing restoration success. Here, the biodegradation behavior of three natural textiles was assessed in different configurations. Coir, sisal, and jute meshes were fixed on the top and bottom of a coir nonwoven mat, forming a so-called “sandwich structure.” Specimens were buried in the Ria Formosa Lagoon, Portugal, and retrieved weekly within the first months of burial and subsequently monthly over a total period of 3 months. Weight, tensile strength, and oxygen consumption rate were used as descriptors for biodegradation and tested after each retrieval. The results obtained in this study were discussed in the context of the application of the tested materials on Zostera marina transplants. Due to experimental errors, these results are solely used for discussion purposes in a conservative manner. Based on the three descriptors, coir mesh was the least degraded by the end of the experiment. Yet, it is vital to analyze the microbiome in a study site to understand the biodegradation process and based on that select a textile material. Coir fibers appear to be a good choice in highly biologically active areas to prolong the degradation process, whereas in areas with less activity sisal could be sufficient and even beneficial through the release of compounds that foster vegetations induced by degradation.

The waters of Letman Village, Southeast Maluku Regency are clam fishing grounds which is a source of income for fishermen. One of the shellfish caught is the Blood Cockle (Anadara granosa). The purpose of this study was to analyse and examine the stock of A. granosa clams in Letman village, Kei Kecil District, Southeast Maluku Regency (length and weight frequency) and to determine the mortality rate and exploitation rate of Blood Cockles. This study was conducted between January and June 2022 with a sampling time of once a month for six consecutive months. Random sampling method was used through a free collection at low tide. The total sample collected during the study was 741 individuals. The research data were analysed using FiSAT II program version 3. The smallest size of the sample obtained during the study was 30 mm and the largest was 69 mm. The infinity length (L∞) is 78.50 mm, the growth coefficient (K) is 0.8/year, and the theoretical lifespan of Blood Cockles at a length equal to zero is −0.514/year. Analysis of the total mortality rate (Z) of Blood Cockles (A. granosa) was calculated at 3.90/year with a natural mortality rate (M) of 1.22/year and catchment mortality (F) of 2.68/year, while exploitation rate (E) was at 0.69/year. The addition of new individuals (recruitment) took place every month with varying numbers and the highest recruitment occurred in July and October while the level of exploitation of Blood Cockle in the waters of Letman Village was considered high (overfishing).

Microplastics, which are microscopic plastic particles smaller than five millimetres, have become a common global pollution in marine environments. These particles, which come from a variety of sources such as the decomposition of bigger plastic objects and the microfibres that are shed from textiles, are extremely dangerous to ecosystems and marine life. This study provides a detailed analysis of the global issue of microplastic pollution, including its origins, effects on marine ecosystems, current mitigation techniques, and future research prospects. The review divides microplastics into main and secondary categories, detailing their sources ranging from plastic pellets and microbeads to the breakdown of bigger plastic items such as bottles and bags. It emphasises the negative impacts of microplastics on marine species, aquaculture, and human health, such as gastrointestinal obstructions, toxic chemical accumulation, and cancer risk to human health. The review also examines the economic and environmental consequences of marine plastic pollution, highlighting the importance of effective policies and remedies. Furthermore, the article covers several researches on microplastic contamination in coastal sediments, seafood, and aquatic creatures from diverse locales. It addresses methods for collecting, extracting, and analysing microplastics, as well as advances in machine learning and spectroscopic techniques for precise identification and measurement. Furthermore, the study summarises the research on the ecological hazards presented by microplastics, such as their movement patterns, accumulation in marine ecosystems, and possible long-term effects. The study also examines the problems and limitations in existing research, such as the need for consistent data collection processes, a better knowledge of microplastic behaviour in various settings, and the development of novel mitigating solutions. Overall, this study gives an in-depth summary of the current state of knowledge on microplastic contamination, emphasising the critical need for more research, legislative interventions, and public awareness campaigns to ameliorate its negative impacts on marine ecosystems and human health.