Early life growth is affecting timing of spawning in the semelparous Barents Sea capelin (Mallotus villosus)

Capelin (Mallotus villosus) is a forage fish and a key species in the Barents Sea (BS). The BS capelin are semelparous and hence only spawn once along the north coasts of Norway and Russia before they die. The age at spawning ranges from 2 to 5 years and the spawning season peaks in March/April but starts in February and lasts until June, and the causes of the variability in timing of spawning are not well understood. Here, we aimed to find out whether early growth is associated with the timing of spawning in BS capelin, both on the individual and population level, and if there is an association between early life growth and the spatial distribution at the nursery areas and feeding grounds. For the analysis, we used an extensive dataset comprising >150 000 otolith growth zone measurements carried out during surveys from 1976 to 2019 both from the spawning and feeding areas. The data from the feeding area showed that capelin with good first-year growth were found in the productive north-west part of the Barents Sea at both age 1 and 2, while capelin with relatively poor first-year growth were typically found in the south-east Barents Sea. The data from the spawning area showed on the individual level that capelin with good first-year growth tend to spawn both at a younger age and earlier in the season. The capelin spawning late in the season were also generally smaller than early spawners. On the population level, a contradictory pattern was observed where the proportion of maturing capelin at age 2 and 3 was negatively correlated with first-year growth indicating that the great variability in year-class strength masks the general effect found at the level of individual fish. Furthermore, first-year growth was positively associated with the abundance of 1-year-old capelin indicating that rapid growth early in life enhances recruitment. On the other hand, first-year growth was strongly negatively correlated with third-year growth suggesting an increased effect of density-dependent growth with age and/or compensatory growth, or reduced growth linked to earlier maturation. In sum, our results show that the first-year growth affects growth, maturation processes, and timing of spawning later in life, thus potentially strongly influencing capelin population dynamics.publishedVersio

Factors leading to variation of spawning time in the Barents Sea capelin (Mallotus villosus)

Barents Sea capelin (Mallotus villosus) is a semalparous fish species, and the timing of spawning both in terms of age and season is variable. The present thesis explores potential factors leading to variation in timing of spawning in this key species of the Barents Sea; hereunder whether seasonal timing of spawning to spring or summer is due to an established strategy and genetically (parentally) determined, or simply a variable phenomenon related to changes in environmental conditions. Comparisons of biological characteristics made between spring spawners and summer spawners in five selected years (1977, 1982, 1984, 1985, 1996) demonstrated that summer spawners were significantly younger, smaller (lower length and weight), with a slower somatic growth and lower condition than spring spawning capelin. Both the first year otolith growth and the ratio between first and second year otolith growth was lower in summer- than in spring spawners. First year otolith growth increased with body length at age, whereas such a relationship was not found with the ratio between first and second year otolith growth. Hypothetically capelin hatched in summer would on average have both a lower first year otolith growth and a lower ratio between first and second year otolith growth than capelin hatching in spring due to a much shorter feeding season in their first year of life. Hence, the observed differences in biological characteristics could be interpreted as capelin returning to spawn in the same season they hatched themselves as parentally determined, i.e. summer spawning is an established strategy. This was further explored using data from the late feeding distribution in the Barents Sea during August-October 1976-2012, which demonstrated that capelin with otolith growth characteristics similar to that observed among summer spawners tended to distribute more to the southeast. Feeding and growth conditions normally tend to be worse when moving towards south east, which may explain the slower growth and condition observed among summer spawners. However, the lower condition in summer could also be linked to the longer period spent from the last main feeding season in autumn until the spawning. Over the period 1976-2012 the first year otolith growth and the ratio between first and second year otolith growth were highly variable, and the fluctuations in these parameters were significantly related to population density (capelin biomass), zooplankton availability and temperature. This signifies that age at spawning, and timing of spawning within an established spawning season may vary with climatic changes and stock fluctuations. It is the conclusion of this thesis that it is not very likely that the climate may cause capelin hatched in spring to spawn in summer. However, one cannot exclude that proportions of capelin spawning in summer may vary with changes in environmental conditions, as the climate effect on recruitment may differ between spawning seasons

Early life growth is affecting timing of spawning in the semelparous Barents Sea capelin (Mallotus villosus)

Capelin (Mallotus villosus) is a forage fish and a key species in the Barents Sea (BS). The BS capelin are semelparous and hence only spawn once along the north coasts of Norway and Russia before they die. The age at spawning ranges from 2 to 5 years and the spawning season peaks in March/April but starts in February and lasts until June, and the causes of the variability in timing of spawning are not well understood. Here, we aimed to find out whether early growth is associated with the timing of spawning in BS capelin, both on the individual and population level, and if there is an association between early life growth and the spatial distribution at the nursery areas and feeding grounds. For the analysis, we used an extensive dataset comprising >150 000 otolith growth zone measurements carried out during surveys from 1976 to 2019 both from the spawning and feeding areas. The data from the feeding area showed that capelin with good first-year growth were found in the productive north-west part of the Barents Sea at both age 1 and 2, while capelin with relatively poor first-year growth were typically found in the south-east Barents Sea. The data from the spawning area showed on the individual level that capelin with good first-year growth tend to spawn both at a younger age and earlier in the season. The capelin spawning late in the season were also generally smaller than early spawners. On the population level, a contradictory pattern was observed where the proportion of maturing capelin at age 2 and 3 was negatively correlated with first-year growth indicating that the great variability in year-class strength masks the general effect found at the level of individual fish. Furthermore, first-year growth was positively associated with the abundance of 1-year-old capelin indicating that rapid growth early in life enhances recruitment. On the other hand, first-year growth was strongly negatively correlated with third-year growth suggesting an increased effect of density-dependent growth with age and/or compensatory growth, or reduced growth linked to earlier maturation. In sum, our results show that the first-year growth affects growth, maturation processes, and timing of spawning later in life, thus potentially strongly influencing capelin population dynamics

Early life growth is affecting timing of spawning in the semelparous Barents Sea capelin (Mallotus villosus)

Capelin (Mallotus villosus) is a forage fish and a key species in the Barents Sea (BS). The BS capelin are semelparous and hence only spawn once along the north coasts of Norway and Russia before they die. The age at spawning ranges from 2 to 5 years and the spawning season peaks in March/April but starts in February and lasts until June, and the causes of the variability in timing of spawning are not well understood. Here, we aimed to find out whether early growth is associated with the timing of spawning in BS capelin, both on the individual and population level, and if there is an association between early life growth and the spatial distribution at the nursery areas and feeding grounds. For the analysis, we used an extensive dataset comprising >150 000 otolith growth zone measurements carried out during surveys from 1976 to 2019 both from the spawning and feeding areas. The data from the feeding area showed that capelin with good first-year growth were found in the productive north-west part of the Barents Sea at both age 1 and 2, while capelin with relatively poor first-year growth were typically found in the south-east Barents Sea. The data from the spawning area showed on the individual level that capelin with good first-year growth tend to spawn both at a younger age and earlier in the season. The capelin spawning late in the season were also generally smaller than early spawners. On the population level, a contradictory pattern was observed where the proportion of maturing capelin at age 2 and 3 was negatively correlated with first-year growth indicating that the great variability in year-class strength masks the general effect found at the level of individual fish. Furthermore, first-year growth was positively associated with the abundance of 1-year-old capelin indicating that rapid growth early in life enhances recruitment. On the other hand, first-year growth was strongly negatively correlated with third-year growth suggesting an increased effect of density-dependent growth with age and/or compensatory growth, or reduced growth linked to earlier maturation. In sum, our results show that the first-year growth affects growth, maturation processes, and timing of spawning later in life, thus potentially strongly influencing capelin population dynamics

Bringing Botany into Focus: Addressing Plant Blindness in Undergraduates Through an Immersive Botanical Experience

Abstract Undergraduate science, technology, engineering, and math students (STEM) are usually not attuned to the intricacies of plant life histories or to the dynamic role plants play in ecosystems and human society, a phenomenon termed plant blindness. Botany education has declined in the past decades, whereas career paths that need and benefit from a workforce with botanical knowledge have increased. Consequently, there is a need to reduce plant blindness among undergraduate students, regardless of their career trajectories. We provide evidence that participation in a botanical experience as part of a general biology course can positively shift undergraduates’ perception of botany, the study of plants. Students participating in the botanical experience showed significant positive shifts in their ability to connect botany to their college major and future careers. In addition, we show qualitative data indicating a new respect for plants and a new appreciation for the diversity among plants.</jats:p