Lecture 8 Flashcards
What are biogeochemical cycles?
Cycles that regulate the movement of nutrients and elements through ecosystems.
What is nitrification?
The conversion of ammonium (NH₄⁺) to nitrate (NO₃⁻) through nitrite (NO₂⁻), requiring oxygen and mediated by bacteria.
What is denitrification?
The reduction of nitrate (NO₃⁻) to nitrogen gas (N₂) or nitrous oxide (N₂O) in anoxic conditions.
What is Michaelis-Menten kinetics?
A description of enzyme-mediated reactions where the reaction rate depends on substrate concentration until reaching a maximum rate.
What is first-order kinetics?
Reactions where the rate depends linearly on the concentration of a single reactant.
What is Henry’s Law?
A law stating that the concentration of a gas in a liquid is proportional to its partial pressure above the liquid.
What are the intrinsic and extrinsic factors affecting fish growth?
Intrinsic factors include species, size, swimming activity, maturity, and age. Extrinsic factors include abiotic (temperature, light, O₂ levels) and biotic (food availability, social hierarchy, predators) influences.
What does the metabolic growth model describe?
It describes how consumed food (C) is used for growth (B) after losses such as feces (F), excretion (U), and metabolic costs (R). Formula: B = C - F - U - R.
What are the assumptions of metabolic growth models?
Assumptions include that all consumed food and fish have the same caloric content
What is the URSIN metabolic model?
A model incorporating parameters for
- digestion (α),
- metabolism (m), and
- feeding efficiency (β).
It predicts sigmoid or exponential growth depending on parameter values.
What happens if m < n in the URSIN model?
The model predicts sigmoid growth, where asymptotic weight (W∞) is large if feeding levels are high.
What does the logistic growth equation describe in population models?
It describes population growth that increases until it reaches carrying capacity (k) and follows a sigmoid curve.
How does a delay in recruitment affect logistic growth?
Delays can cause oscillations or fluctuations in population size before stabilizing near carrying capacity.
What is the Schaefer model, and what does it represent?
A fisheries model that describes yield as a function of biomass (B) and fishing pressure (Y), identifying Maximum Sustainable Yield (MSY).
How do the Fox and Pella-Tomlinson models differ from the Schaefer model?
The Fox model uses a logarithmic function for growth, while the Pella-Tomlinson model includes an additional parameter (m) to adjust the shape of the growth curve.
Why is Maximum Sustainable Yield (MSY) important in fisheries management?
MSY represents the maximum yield that can be harvested without depleting the population, ensuring sustainable exploitation.
Metabolic growth model are based on the fate of consumed food
The abundance of marine populations fluctuates over time and space, because of:
what are SURPLUS PRODUCTION MODELS
