Marine Ecology-An Evolutionary Perspective最新文献

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.

There are unique reef patches in the Biosphere Reserve Banco Chinchorro reef lagoon that have an unusual formation. They appear to be miniature atolls. These formations are at a depth of 2–6 m, and present flourishing coral growth, whereas a few meters away others are strongly decayed. To define the cause of this phenomenon, an analysis of three of these formations was carried out to try to relate the structure of the corals that make up these formations to environmental factors. We recorded in tidal cycles, 12 environmental parameters, and micronutrients. Despite their closeness, two patches show high biodiversity, whereas the third shows low diversity. These results show notable differences between the three patches resulting from position on the reef (leeward and windward), in addition, these patterns relate to the undercurrent of possible relict water that drains from the lagoon microsystem of the main island of the reef, Cayo Centro, toward the miniature atolls.

A study conducted from January to December 2018 examined seasonal variations in horizontal phytoplankton communities. A total of 93 species were identified, including 63 Coscinodiscophyceae, 4 Fragilariophyceae, 7 Bacillariophyceae, 15 Dinophyceae, and 4 Cyanophyceae. The highest species diversity and abundance occurred during the postmonsoon and premonsoon periods. Environmental parameters (viz., temperature, salinity, dissolved oxygen, pH, ammonia, nitrite, silicate, total suspended solids) were all statistically significant except for nitrite (p > .05). Multivariate statistical analyses (PCA and CCA) revealed that in the postmonsoon period, silicate and nitrate were responsible for the proliferation of phytoplankton abundance, species composition and density, while in the premonsoon period, temperature, salinity, and pH significantly influenced and favored specific phytoplankton groups (such as Chaetocerotaceae) in terms of species composition and abundance.

The Patagonian toothfish or Chilean sea bass, Dissostichus eleginoides, is an ecological and commercially important species captured by the Equatorian fleet in the Southeast Pacific Ocean. This study aimed to determine this species' diet composition and feeding habits captured in three geographical zones from Ecuador during 2017 and 2018. The total length and corporal mass were measured during this period, and the sex and sexual maturity states were determined from 328 individuals. A hypoallometric growth was evidenced by the size-weight relationship in D. eleginoides, with an allometry coefficient b = 2.34, suggesting that it increases in size more than in weight. The stomach content analysis expressed as the Prey Specific Index of Relative Importance (PSIRI) indicated that D. eleginoides mainly feeds on teleost fish (88.2%) and less on cephalopods (9%) and crustaceans (2.8%). Males and females evidenced a similar diet; however, adults consumed more teleost fish than juveniles. The trophic position ⁓ 4 indicates that the Patagonian toothfish is a secondary carnivore predator with a wide geographic and diet variation related to prey availability. This is the first study regarding the trophic ecology of D. eleginoides in Ecuador, as other studies are lacking. Understanding nutrient and energy flows in ecosystems is crucial for effective fishing management with an ecosystemic approach.

The population of common cuttlefish Sepia officinalis in the English Channel recently developed two life cycles: annual (spawning 1 y.o.) and biennial (spawning 2 y.o.) instead of the biennial strategy known before, associated with increasing environmental temperatures in recent decades because of climate changes. Both groups differ in the size of mature animals (110–196 mm mantle length vs. 140–262 mm) and the number of chambers in the cuttlebone (60–97 in annual vs. 93–152 in biennial). The annual group represented some 15%–20% of the population, and the proportion of early spawners increased during the reproductive period, from 3%–5% in February/March to 50%–70% in June/July. Among spawning cuttlefish males predominated as ~2:1. Such environmentally driven changes in historical ecology as exemplified by the cuttlefish might be a critical link in the adaptation of the cephalopod life cycles to changing ecosystems.

Deep-sea chemosynthetic ecosystems are ‘oases’ of life powered by reducing geofluids, of which serpentinite-hosted seeps are among the least studied. South Chamorro Seamount, a serpentine mud volcano on the Mariana Arc, has been known to host chemosynthesis-based assemblages since 1996, but no detailed information on the fauna was published. Here, we revisited South Chamorro to characterise its biodiversity. We located two regions of chemosynthetic communities dominated by bathymodioline mussels, vesicomyid clams, and chaetopterid parchment worms: one on the northwestern flank (‘Fryer Site’) and one on the southern summit (‘Summit Site’). We sampled a total of 20 species including 13 molluscs, five annelids, and two crustaceans – all present on the more active Summit Site but only a subset being found at Fryer Site. A mussel bed surrounding the Fryer Site was drilled by the Ocean Drilling Program in 2001 resulting in six holes, the deepest being 266 m (Hole 1200C). Cuttings ~50 cm deep still cover an approximately 60 m radius around Hole 1200C even 22 years later, and there is no sign of recovery. Low geofluid supply in serpentinite-hosted seamounts may not allow decadal recovery of animal colonies, unlike a previous drilling site in an Okinawa Trough vent.

Octopus insularis is a shallow-water octopus distributed throughout the western Atlantic, the Gulf of Mexico and the Caribbean. To evaluate its phylogeographic pattern, mitochondrial markers (16S rRNA and COIII) and genome-wide nuclear markers (SNP's) were analyzed in individuals from artisanal fishing in different locations of the Colombian Caribbean coast. Mitochondrial analyzes displayed novel haplotypes (16S = H2, H3 and H4; COIII = H2–H7) and haplotypes shared with distant geographic areas (16S = H1 COIII = H1). The COIII gene did not show genetic differentiation between the analyzed localities, while the 16S gene showed significant differences between Santa Marta and Isla Fuerte. COIII's demographic analysis indicated that the species' effective population size has remained constant. Inferences were made from next-generation genomic data with restriction site-associated DNA (ddRAD-seq) and 6769 polymorphic loci. The pairwise F_ST test indicated that there are low but significant differences between localities; however, the general molecular analysis of variance (AMOVA) and the principal coordinate analysis showed a lack of spatial structure in the populations analyzed. The Mantel test found no correlation between genetic distance and geographic distance, and the genetic structure analyses showed the presence of one genetic stock. The information obtained in this study indicates the genetic connectivity of O. insularis in the southwestern Caribbean, the absence of putative biogeographic barriers that affect its gene flow, and the crucial role played by life history strategies (planktonic paralarvae) and oceanographic factors to define the current distribution of its genetic diversity in this region.

Laboratory microcosm experiments help to understand the degradation pattern of different sources derived from organic matter (OM) at the sediment–water interface and relate it to field processes. Microcosm experiments were carried out for 65 days to assess the degradation of organic materials such as diatoms, zooplankton, and mangrove leaves using source-specific fatty acid (FA) biomarkers. The viable bacterial population in the microcosm sediment was low on day 1, but on day 3, it increased substantially by two to threefold in all the treatments. An increase in the bacterial population resulted in a decrease in the FAs specific to organic materials during the initial incubation phase (10 days), suggesting the degradation of organic materials derived from different sources. The FAs specific to diatoms showed faster degradation when compared to zooplankton and mangrove-specific FAs. The degradation of FAs was influenced by the nature of the source material, unsaturation of FAs, and the sediment type. Sandy sediment facilitated higher degradation of diatom and zooplankton-specific FAs, whereas mangrove-specific FAs showed higher degradation in silty-clay sediment. Thus, bacterial community composition coupled with the habitat characteristics, the OM composition, and the grain size of the sediment, influenced the degradation of FAs. The degradation of mangrove-specific long-chain FAs was ~1.11–2.5 times higher when spiked with plankton-derived labile OM from mixed sources, which otherwise took a longer time for degradation pointing toward co-metabolism (priming effect), which could play a significant role in the cycling of terrestrial plant-derived OM in an estuarine ecosystem.

Abiotic stresses encompass different environmental stimuli and constantly affect plant sustainability throughout their lifetime. Plants have developed several complex mechanisms to respond against these abiotic stresses. Studies have shown that microRNAs (miRNAs) effectively reduce stress-responsive genes that significantly help plants tolerate abiotic stresses such as drought, salinity, temperature, and heavy metals. The regulation of such genes by miRNAs not only aids in plant growth and development but also controls physiological processes such as identifying floral organs, leaf morphogenesis, and root development. As per the information, miRNA plays an important role in stress regulation and regulates homeostasis in mangrove plants such as Rhizophore apiculata. Several modern technologies and approaches have been developed to determine these stress response miRNAs. The targeted genes of miRNAs are transcription factors that further control a set of down and upstream genes to affect physiological response. This paper explores the miRNAs found in a mangrove plant Avicennia marina. The plant contains many miRNAs and knowledge of miRNAs – their development, roles, functions, and target genes under abiotic stress conditions.