Abstract This research aims to investigate temporal and spatial distribution of planktonic copepods in relation to enviromental factors at five stations in Kaoping coastal waters, and their feeding impact on phytoplankton during September 1999 to June 2001. In total, 79 species of copepods belonging to 19 families and 4 orders, plus 23 unidentified species, were found from the samples collected by the plankton net with 330 µm mesh. The mean abundance of the collected copepods is 4.2¡Ó2.0 x104 ind./100m3. The number of copepod species in each sample varied from 34 to 61, and the species diversity index of the samples ranged from 2.4 to 3.8. The abundance of copepods in surface tows was generally higher than that of 100 meter oblique tows, and vice versa of the species number and species diversity index. Temora turbinata, Acrocalanus spp., Paracalanus spp., unidentified copepodites and Farranula gibbula were the five most dominant species, contributing to 53.2 % of the total copepod abundance. T. turbinata was the most abundant species (20.4 % of the total catch). The abundance of copepods were highter in March and September than in June and December and lower at offshore stations than at inshore stations. The total copepod abundance was significantly correlated with salinity and chlorophyll a. And, it was interpreted that the community structure and distribution of copepods were influenced by coastal upwelling, change of water mass and river effluence. Another sampling at the same stations during September 2000 to June 2001, in total, 48 species of copepods belonging to 16 families and 4 orders, plus 15 unidentified species were found from the samples collected by the plankton net with 100 µm mesh. The mean abundance of the copepods is 33.5¡Ó9.9 x104 ind./100m3. The number of copepod species in each sample varied from 27 to 38, and the species diversity index of the samples ranged from 3.0 to 3.2. Copepodite, Oithona spp., Paracalanus spp., Nanuplius, Oncaea venusta and Euterpina acutifrons were the six most dominant species or taxa, contributing to 75.2% of the total copepod abundance. The abundance of copepods were higher in June and September than in March and December and lower at offshore stations than at inshore stations. The fact that total copepod abundance was significantly correlated with salinity and chlorophyll a was explained of that the community structure and distribution of copepods were probably influenced by river effluence. The abundance and species number of copepods collected by the net with 330 µm mesh and 100 µm mesh were significantly different. The abundance of copepods collected by the 100 µm mesh net was about 8 times higher than that of 330 µm mesh net, but the number of copepod species was about 25 species less. In all, the grazing impact of copepods on phytoplankton was minor, it was between 0.90 to 1.25% per day in June and between 0.44 to 4.55 per day in November.

The seasonal and spatial changes in species composition and abundance of copepods in relation to environment factors in both Tanshui and Kaoping estuaries were investigated in 2003. In total, 99 copepod species belonging to 8 genera and 3 families and 113 species belonging to 25 genera and 4 families were identified in the Tanshui and Kaoping estuaries, respectively; correspondingly each with the mean abundance of 1680 ¡Ó 403 inds/m3 and 3682 ¡Ó 1274 inds/m3. The species composition of copepods was apparently different between Tanshui and Kaoping estuaries. In the Tanshui estuary, the 6 most dominant copepods, Temora turbinata, Euterpina acutifrons, Canthocalanus pauper, Acrocalanus longicornis, Acrocalanus gibber, and Nannocalanus minor, were all marine species; among them, T. turbinata was the most abundant and contributed 11.9% to the total copepod count. While in the Kaoping estuary, many dominant species were freshwater dwellers, such as Pseudodiaptomus annandalei, Neodiaptomus schmackeri, Microcyclops tricolor, and Paracyclops fimbriatus. P. annandalei was the most abundant species and contributed 8.3% to the total copepods. The dominant marine species in the Kaoping estuary were Pseudodiaptomus marius, T. turbinata, Acartia omorii, Cosmocalanus darwini and Paracalanus parvus. The species composition and abundance of the copepods exhibited noticeable seasonal changes in both estuaries, particularly in the Kaoping estuary, probably related to the intensities of monsoon, rainfull and runoff of freshwater. In the Tanshui estuary, copepod assemblages were short of clear seasonal changes; the dominant species, Temora turbinata, Euterpina Acutifrons, and Canthocalanus pauper were found in all sampling months, with the peak abundance of these species as well as of the total copepods in May and lowest in November. In the Kaoping estuary, the peak abundance was found in February and lowest in August, while P. annandalei and Mongolodiaptomus birula were the most dominant species in these two months, respectively. The copepod (with the exception of Acrocalanus longicornis) abundance in the Tanshui estuary showed insignificant correlation with environmental factors, having significant and negative correlation with temperature. In the Kaoping estuary, on the other hand, most copepods were negatively and significantly correlated with both temperature and salinity.

Abstract In the laboratory, we examined the effects of food types and temperatures on the growth and reproduction of the copepod Apocyclops royi. Three types of experiments were conducted: (1) effects of food type using four microalgae, Chaetoceros muelleri, Isochrysis galbana, Tetraselmis chui and Nannochloropsis oculata, and seven artificial feeds, BP-1000E, GSP-500, Micro-Mac£s30, Algamac-2000, DHA-Protein Selco, Culture Selco, and Baker's yeast; (2) effects of feeding frequency of artificial diets; and (3) effects of temperature. The survival rate, development time, longevity, female ratio, reproduction duration and fecundity were used to assess the responses of copepod. The results showed that growth and reproduction of copepods fed with algae, exclusive of Nannochloropsis oculata, are better than those fed with artificial diets. The copepods fed with T. chui grew fastest, matured in average 8.7 days after hatching and have the maximal fecundity, 13.5 nauplii/female/day. Among artificial diets, copepods fed with Culture Selco have the highest survival, 70.8¢M, which is comparable to those fed with alage, but took longer time, 17.5 day in average, to become matured. Those fed with Micro-Mac£s30 have the higher fecundity but only 9.1 nauplii/female/day. After changing feeding frequency from one to three times a day, the survival rate of those fed with BP-1000E and DHA-Protein Selco was significantly improved but it was still lower than those fed with Culture Selco once per day. Although the production of copepods fed with DHA-Protein Selco increased, it was still lower than those fed with Micro-Mac£s30. When cultured at 25, 30 and 35¢J, the survival rate and production of copepod A. royi were not affected by temperature but the maturation time decreased with increasing temperature. At 35 ¢J, females became matured in 6.7 day and the fecundity is 14.2 napulii/female/day. In conclusion, food type is the major factor affecting growth and reproduction of A. royi and algae is the better food in this study. Temperature mainly affects the growth rate. High water temperature can increase growth rate and shorten the maturation time. In addition, our studies also found that the food containing higher contents of protein did not assure better survival rate or reproduction of copepod. The algae T. Chui barely containing DHA did not cause the lower survival rate or reduced reproduction. In term of growth rate and production, the estuarine copepod A. royi is a potential food organism for mass culture.

The principal objectives of this research are to investigate seasonal and spatial variabilities of species composition and numerical abundance of the copepods in relation to environment factors in the Kaohsiung Harbor and it¡¦s adjacent coastal waters, and compared the carbon ¡B nitrogen and hydrogen contents of the animal. In all, 61 species of copepods belonging to 16 families were identified from the samples collected at six stations in the Kaohsiung Harbor. The mean numerical abundance of copepods was 5.3 ¡Ó4.8 ¡Ñ10 5 inds/100m 3 . The dominant and frequent species were Parvocalanus crassirostris, Oithona dissimilis, Oithona brevicornis, Acrocalanus spp. and immature copepods (copepodite and nauplius), amounting to 91% of the total copepods catch. Among them, P. crassirostris was the most abundant and frequent species (contributed to 30% of the total catch). The numerical abundance of copepods exhibited seasonal and tidal variations, with higher abundance in spring and winter and during the high tide. The species composition of the copepods in the harbor was different from that of the local coastal water, with higher abundance and species number in the latter. From the monthly collections at a fixed station north of Kaohsiung Harbor, 42 species of copepods were identified and the mean abundance of copepods was 3.3 ¡Ó3.6 ¡Ñ10 5 inds/100m 3 . The most dominant and frequent copepods was Parvocalanus. crassirostris, O. dissimilis, O. brevicornis, Acrocalanus spp., Euterpina acutifrons and immature copepods, contributing to 92% of the total numerical abundance of copepods. The abundance of copepods exhibited significant seasonal change at this station, with higher abundance in winter and summer and lower in spring. The carbon content and dry weight of copepod were not significantly different between harbor and coastal water, but copepod¡¦s carbon content showed significant difference among body sizes. Copepod dry weight was significantly different among body sizes, but not seasons.

As one of the most abundant metazoan groups on the planet, copepods are found in virtually all marine environments. They provide a key link in marine food webs between photosynthetic algae and higher trophic levels. Subsequently, copepods are preyed upon by a wide variety of organisms throughout their life history. As a result copepods have evolved a powerful escape behavior at all stages of development, in response to hydrodynamic stimuli created by an approaching predator. Typically copepods exhibit 6 naupliar stages and 5 copepodite stages before becoming adults. This work focuses on quantifying the effectiveness of the escape behavior during key periods of development. The earliest developmental stage of copepod (nauplius N1) experiences the greatest amount of viscous forces and may be at a disadvantage when exposed to larger predators at cold temperatures. The results show that the nauplius exhibits a compensatory mechanism to maximize escape performance across its thermal range. Later in development, the nauplius (N6 stage) molts into a copepodite (C1 stage) which resembles the body form of an adult copepod. Here, there is a significant morphological change with little change in mass. Escape capabilities are investigated for key stages in response to feeding strikes from natural fish predators. The results demonstrate that the improvement in escape capability of the C1 stage is effective only against certain modes of predation. Finally, successfully escaping from predation has evolutionary fitness implications and adults (post C5) are the only reproductive stage. Some species have developed unique mechanisms to avoid predation such as breaking the water surface and making aerial escapes to avoid predators while in other cases, the predator has developed unique morphology in order to reduce the amount of hydrodynamic disturbance in the water which improves capture success of copepods. By investigating copepod behavior and their ability to avoid predation at various stages of development, we can begin to understand which stages copepods are most susceptible to different types of predators and how the escape response changes as development progresses. This can help in understanding localized abundances or deficiencies of both predator and prey in the marine food web. / text

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Areas of hypoxia are found in coastal areas worldwide, and have become increasingly widespread. These areas vary in their duration and dissolved oxygen concentration from occasional diurnal hypoxia, as found in Corpus Christi Bay, Texas, seasonal hypoxia as in the northern Gulf of Mexico, to continuous hypoxia as found in oceanic oxygen minimum zones. The effects of exposure to low dissolved oxygen (DO) depend on the duration of exposure, the DO concentration and an organism’s tolerance to hypoxic conditions. Most studies have focused on lethal effects of hypoxia by comparing the abundance of benthic organisms and the species composition of benthic communities between hypoxic and normoxic areas. Sub-lethal effects of such as changes in reproduction may occur at less severe hypoxic conditions (by definition), but may still have effects at the population level. The goal of this study is to examine the sub-lethal reproductive effects of low DO on harpacticoid copepods. The life-history traits and reproductive biology of meiobenthic harpacticoid copepods make this group of organisms useful as test organisms to measure the sub-lethal effects of hypoxia on reproduction. It is hypothesized that changes in reproductive traits may be observed at DO concentrations higher than those that cause lethal effects because of the high energetic cost of female harpacticoid reproduction which may result in reduced fitness. Laboratory studies were conducted to examine the effects of low DO concentrations on survival, egg production, and the number and size of eggs. Harpacticoid population abundance, biomass and the abundance of ovigerous females were measured from field samples collected across sites that varied in their degree and duration of exposure to low DO. To contrast the effects of hypoxia in environments with different hypoxic exposures, field studies were carried out in the northwestern Gulf of Mexico in an area with near constant summer hypoxia, and in southeast corner of Corpus Christi Bay, Texas which experiences intermittent hypoxia often for less than one hour in the early morning hours during summer. At both field sites total copepod abundance, biomass and the abundance of ovigerous females were reduced at the most hypoxic site type compared the reference sites. In Corpus Christi Bay, total and ovigerous female abundance varied with exposure to hypoxia, but the relative declines in abundance and biomass were less dramatic than in the northern Gulf of Mexico. In the northern Gulf of Mexico, the percentage of ovigerous females within the total harpacticoids collected was reduced (p<0.001) to 3% at the Intermediate and 1% at the Hypoxic sites during the summers, but in the fall of 2007 at all transects had similar percentages (p = 0.81) of ovigerous females which ranged from 13 to 16%. Reference sites had a higher number of families with ovigerous females, and the relative abundances of those families were more evenly distributed at Reference sites compared to Hypoxic and Intermediate transects. Patterns of ovigerous female abundance with respect to DO concentration were similar across numerous harpacticoid families found at the study sites. Harpacticoid copepods in laboratory studies tolerated near anoxic DO conditions for longer than 120 hours. Average survival rates of the harpacticoids Schizopera knabeni and Nitokra affinis during periods of low DO with elevated ammonium concentrations were less than 50%, while survival rates for the other treatments were near 100%. The formation of an egg mass was reduced in the near anoxia treatment, but egg clutches did not form at all in the treatment that combined near anoxia and 10 micromolar ammonium. The DO concentration and presence of ammonium were important factors to the severity of population decline that were illustrated by population estimate calculations. Population estimates based on laboratory measurements of Nitokra affinis resulted in calculations of reduced survival and reproductive rates related to hypoxic exposure greatly decrease the potential population of the group, which may affect the copepod population’s ability to recover from hypoxic events. The effects of hypoxia on harpacticoid copepods are the result of the length of exposure, the concentration of low dissolved oxygen and exposure to other chemical fluxes that increase during periods of hypoxia. The measurement of reproductive indicators, such as the presence of an egg mass and the proportion of ovigerous females in a population, could be used to indicate the adverse environmental effects of low dissolved oxygen exposure. The studies from this dissertation are the first to document reproductive effects of low dissolved oxygen on harpacticoid populations in the field. Laboratory studies within this dissertation indicate the interaction between ammonium and hypoxia on survival and reproduction in harpacticoids. Future studies are needed to further determine the effects of hypoxia on the whole-life cycle of harpacticoid copepods. / text

Thesis (M.A.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / In all, 7587 copepods were recovered from 115 pelagic snails of two species, Janthina janthina (Linnaeus) and J. globosa Swainson, which had been collected from the West Indies,and Madagascar. They were found either free inside the mantle cavities or fixed on to the gill lamellae of the snails, and represent a complete series of the postembryonic developmental stages of a lernaeoceriform copepod. Five stages were recognized. They are: 1. Free-swimming copepodid: 0.42-0.48 mm. The body has an oblong cephalothorax and four free segments. There are two pairs of well-developed biramous legs. The third pair is represented merely by a pair of spines on the second free segment. The third free segment represents the fourth thoracic segment and carries no legs. The last free segment carries a pair of caudal rami which bear 4 plumose setae and one short setule. The first antenna is indistinctly 4-segmented, with the formula 1, 1, 1, and 11 plus one aesthete; the two long setae on the terminal segment are bifurcate. The second antenna is 3-segmented, chelate and powerful. The mouth tube is of the usual form found in lernaeoceriform copepods, There is, however, a pair of spatulate labial palps which have not been described before in any known lernaeoceriform copepodids. The mandible is lanceolate, without teeth. The first maxilla is bipartite: a small exopod armed with a single seta and a large endopod tipped with two stout setae. The second maxilla is 3-segmented, with a falciform terminal segment bearing striations. Each ramus of the first two pairs of legs is 1-segmented; the first exopod: III,I,3; the first endopod: 7; the second exopod: II,I,3; and the second endopod: 6 [TRUNCATED]. / 2031-01-01

The small-scale vertical migration patterns and spatiotemporal variations of copepods in the Tapong Bay, southwestern Taiwan, from 2003 to 2005 were studied. The differences in species composition and abundance of copepods before and after the removal of oyster culture racks in relation to tides, hydrography and other environmental factors were also compared and herein discussed. Tapong Bay has distinct dry (October to April) and wet (June to August) seasons and exhibits apparent inter-annual variation, cold, saline and low Chl a concentration in dry season, and vice versa in wet season. Most copepod species displayed normal diel vertical migration, descending to the deeper water during daytime and ascending to near surface water at night. Copepods were always more abundant at night than during daytime. Higher abundance but smaller species number of copepods were found during ebb than flood tides. In all, 123 copepod species belonging to 18 families and 31 genera were identified. Oithona oculata, Parvocalanus crassirostris, Acartia sinjiensis, Acartia sp., Bestiolina amoyensis and copepod nauplius were predominant and together they composed 74% of the total number of copepods. These dominant species showed apparent seasonal changes, with higher abundance in autumn and winter. Copepod assemblage also showed apparent difference between stations. Warm-saline-coastal species dominated in the outer region, while small-size taxa and common species of estuaries and aquaculture ponds dominated in the inner bay. Results of indicator species analysis could possibly recognize the area affected by tides and water masses, and identified Acrocalanus gracilis to be the indicator species of flood tide and outer region of the bay, and Acartia sinjiensis the indicator species of ebb tide and inner bay. Our results showed that after the removal of oyster culture racks the species number and abundance of copepods were higher but the seasonal and spatial differences in abundance became smaller. Furthermore, the increase in abundance of zooplankton and copepods in the Bay after the removal of oyster culture racks might be due to the absence of oyster population which exerts great filter¡Vfeeding impact on phytoplankton, and decrease of predation pressure from moon-jelly that usually aggregated in the inner Bay and settled down their polyps on the oyster racks but disappeared after the removal.