Ocean Species Distribution

1. Ocean Species Distribution • Analyze factors that affect productivity and species distribution in marine and fresh water environments

2. Factors Affecting Ocean Species Productivity • Several factors affect ocean species productivity (reproductive success and life span). These factors include: • Ocean Temperature • Ocean Salinity (the ‘saltiness’ of the ocean) • Amount of oxygen in ocean • Acidity of ocean • There have been significant changes in all of these factors over the past few decades, which has affected many ocean species around the world.

3. Factors Affecting Ocean Species Distribution and Productivity • Some significant changes over the past few decades have been: 1. The average ocean surface temperatures have increased significantly since the 1970s 2. The ocean has become fresher (less ‘salty’ – lower salinity) and more acidic in several areas worldwide 3. The amount of low-oxygen ocean areas have increased • We will now explore how these have affected many species of animals

4. 1. Increased Air and Ocean Water Temperatures • The average ocean surface temperatures have increased significantly since the 1970s • The increase of these average ocean temperatures have had a negative impact on the reproductive success of several species of fish and sea mammals. • For example, climate change directly affects the reproductive success of sea turtles in three ways: • 1. Sea level rise will affect significant nesting beach areas on low-level sand beaches. • 2. Rising temperatures increase the chance that sand temperature will exceed the upper limit for egg incubation which is 34 degrees C. • 3. Rising temperatures bias the sex ratio toward females because temperature during incubation determines the sex of the egg. This means that at a higher temperature, many more females than males are born.

5. Ocean Species Distribution • Temperature has shown to play the most important role in ocean species distribution • It has been shown that as ocean temperatures rise, many ocean species are beginning to travel into the cold and harsh Arctic waters. • Other studies have shown that the distribution of marine life shows two patterns: • Coastal species (corals, coastal fishes, etc) tend to have the highest diversity around Southeast Asia • Open-ocean creatures (tunas, whales, etc) have much higher diversity towards the middle of the oceans

6. 2. Decreased Salinity & Increased Acidity of Ocean • The ocean has become less salty (salinity has decreased) around the world. • This decreased salinity has lead to increased ocean acidification (oceans being more acidic). • This increased ocean acidification has greatly affected several ocean species. The most significant impact has been on marine organisms that build a calcium carbonate skeleton or shell (i.e., scallops, mussels, crabs, shrimp, starfish, etc), as the increased amount of acid in the ocean does not allow them to build these shells/skeletons as effectively. This has decreased biodiversity.

7. 3. Increased Low-Oxygen Areas in Ocean • Low oxygen concentrations have been observed in a number of ocean areas. • Declines in oxygen concentration are caused by changes in ocean circulation patterns, freshwater inputs (i.e., more melting ice running into the ocean), and rising temperatures. • Low oxygen in the ocean has decreased the biodiversity of species in Canadian waters by: • Altering food webs (eliminating plants and animals) • Favouring some species (those who can survive in low-oxygen zones) over others (those who cannot survive in low-oxygen zones; i.e., bottomdwelling animals)

8. Marine Food Webs • Ocean food webs have greatly changes over the last few decades. • One important change has been the changes that have occurred in phytoplankton (microscopic plants, bacteria, and algae, which are the staple of food webs) blooms. • Many phytoplankton blooms start earlier, are more intense (greater), and last longer on the Scotian Shelf than they used to.

9. Changes in Population Trends • Many ocean species populations are interrelated. • A significant trade has been found between the populations of shrimp and groundfish (succh as redfish, skate, atlantic cod, and snow crabs). • It has been found that as the population of groundfish decreases, the population of shrimp increases. • This is because groundfish feed on shrimp, and if there are less groundfish, then shrimp populations can bloom.