ABSTRACT
As a vulnerable species identified by the International Union for Conservation of Nature (IUCN), Lepidochelys olivacea has attracted extensive attention in recent years. To examine its current distribution and that under future climate change scenarios, we compiled the occurrence data of L. olivacea. With eight predictor variables, including depth, offshore distance, mean primary productivity, minimum primary productivity, mean sea surface temperature, minimum sea surface temperature, mean sea surface salinity, and minimum sea surface salinity, we predicted its distribution in an ensemble species distribution model. The accuracy of the model was evaluated with the parameters of areas under curves (AUC) and true skill statistics (TSS). The results showed that the AUC and TSS values were 0.96 and 0.81, respectively, indicating a good predictive performance of the ensemble model. Sea surface temperature and salinity were the two most important variables determining the distribution of L. olivacea, with the suitable temperature ranging from 23 to 29 â and salinity below 34. The current distribution range of L. olivacea was between 30° N-25° S. Under future climate scenarios, its distribution range would decrease, especially under the RCP85 scenario in the 2100s (with a 28% reduction in the suitable survival range). The results of model validation showed that it had high accuracy and could make accurate predictions of the distribution. This study would provide references for the development of more rational conservation measures and management strategies.
Subject(s)
Climate Change , Salinity , TemperatureABSTRACT
To analyze the feeding habits and trophic level of jellyfish (Rhopilema esculentum), Chinese shrimp (Fenneropenaeus chinesis), grass shrimp (Penaeus monodon), and clam (Ruditapes philippinarum), and the food web structure in marine aquaculture pond, we measured the δ13C and δ15N values of the four species and different feed from May to September in 2017. The average proportional contribution of different feed to the four species were analyzed using the IsoSource linear mixture model. The results showed that zooplankton was the main food source to jellyfish, Engraulis japonicus was the main food source to the two shrimp species, and the phytoplankton, benthic diatoms and dejecta of the two shrimp species were the main food source to the clam. The trophic level of the clam ranged from 2.64 to 2.95, with a mean value of 2.84. The trophic level of jellyfish ranged from 2.78 to 3.27, with a mean value of 3.06. the grass shrimp ranged from 3.03 to 3.54, with a mean value of 3.25. The trophic level of Chinese shrimp ranged from 3.76 to 4.40, with a mean value of 3.95. Results of comprehensive analysis showed that the clam was the primary consumer, jellyfish was the secondary consumer, and shrimps were the predators. Jellyfish filtered the dejecta of the two kinds of prawns and improved water quality of the polyculture pond to a certain extent.
Subject(s)
Food Chain , Ponds , Animals , Nitrogen Isotopes/analysis , Shellfish , ZooplanktonABSTRACT
Fourteen current-use pesticides (CUPs) in the surface seawaters of the typical Liaoning sea areas were analyzed using HPLC-MS/MS. The concentrations, distribution, and ecological risks were studied, as well as their source appointments using principal component analysis (PCA). The results revealed that seven types of CUPs were detected in the surface seawaters of the typical Liaoning sea areas. The total concentrations of these CUPs ranged from 16.7 ng·L-1 to 176.1 ng·L-1. The samples with high concentrations were collected mostly from the estuary, and the concentrations of CUPs in the western Liaodong Bay were generally higher than those in the northeastern Yellow Sea. Atrazine and triadimenol were the predominant CUPs, and their contribution rates accounted for 56.0% and 34.5%, respectively. The PCA results indicated that six types of CUPs might be caused by the runoff from farmlands and the wastewater discharge from the chemical pesticide factory, and fruit planting could be a substantial contributor to the single component acetochlor. Atrazine and acetochlor posed medium-high ecological risks to the microalgae, while all the seven types of CUPs showed relatively lower risks to invertebrates and fish.
Subject(s)
Pesticides , Water Pollutants, Chemical , Animals , China , Environmental Monitoring , Pesticides/analysis , Seawater , Tandem Mass Spectrometry , Water Pollutants, Chemical/analysisABSTRACT
The complete mitochondrial genome of the king penguin Aptenodytes patagonicus was firstly determined. The mitogenome is 17,477 bp in length and contains 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a control region. The total nucleotide composition is 31.0% A, 22.2% T, 33.1% C, and 13.8% G, with a total A + T content of 53.2%. The phylogenetic analysis demonstrates a close relationship between A. patagonicus and A. forsteri. These results provide fundamental information for further phylogeny and genetic studies on Aptenodytes genus.
ABSTRACT
This study analyzed the values of δ13C and δ15N by the application of stable isotope technique from the marine mammals (Phoca largha, Neophocaena asiaorientalis sunameri, Balaenoptera acutorostrata) and major biological species in Dalian marine area based on the animals collected due to stranding and death after bycatch from January, 2008 to June, 2017, and the fisheries resources investigation between autumn, 2016 and spring, 2017 in the same area. The trophic level was then calculated in order to establish the continuous trophic spectrum of the food web in Dalian marine area. The results showed that the value of δ15N ranged from 8.0 to 14.7 and the value of δ13C ranged from -21.1 to -16.7 of the food web in Dalian marine area. The major biological species could be categorized into three groups, namely primary consumer, secondary consumer and top predator. The analysis of δ15N revealed that the trophic level ranged from 2.63 to 4.59 for the major biological species. The trophic level of B. acutorostrata, N. asiaorientalis sunameri, P. largha, echinoderm, cephalopods, gastropod, bivalve, crustacean and fish were 3.16, 4.11, 4.25, 3.24-3.84, 3.81-3.93, 3.65-4.13, 2.63-3.15, 3.58-4.12 and 3.20-4.59, respectively. The characteristics of the trophic structure demonstrated that the primary consumer was bivalve, the secondary consumers were B. acutorostrata, cephalopods, Echinoderms, gastropod and crustacean, and top predators were N. asiaorientalis sunameri, P. largha and fish. The value of δ15N increased with the increase in the body length, indicating the feeding of N. asiaorientalis sunameri tended to be at a higher trophic level with the growth and feeding ability enhanced. This study established the continuous trophic spectrum of food web in Dalian marine area and would provide the information for the marine mammal and fisheries resources protection.
